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Optimization of fractured well performance of horizontal gas wells
In low-permeability gas reservoirs, horizontal wells have been used to increase the reservoir contact area, and hydraulic fracturing has been further extending the contact between wellbores and reservoirs. This thesis presents an approach to evaluate horizontal well performance for fractured or unfractured gas wells and a sensitivity study of gas well performance in a low permeability formation. A newly developed Distributed Volumetric Sources (DVS) method was used to calculate dimensionless productivity index for a defined source in a box-shaped domain. The unique features of the DVS method are that it can be applied to transient flow and pseudo-steady state flow with a smooth transition between the boundary conditions. In this study, I conducted well performance studies by applying the DVS method to typical tight sandstone gas wells in the US basins. The objective is to determine the best practice to produce horizontal gas wells. For fractured wells, well performance of a single fracture and multiple fractures are compared, and the effect of the number of fractures on productivity of the well is presented based on the well productivity. The results from this study show that every basin has a unique ideal set of fracture number and fracture length. Permeability plays an important role on dictating the location and the dimension of the fractures. This study indicated that in order to achieve optimum production, the lower the permeability of the formation, the higher the number of fractures.
Magalhaes, Fellipe Vieira
Well test analysis in fractured media
The behavior of fracture systems under well test conditions and methods for analyzing well test data from fractured media are investigated. Several analytical models are developed to be used for analyzing well test data from fractured media. Numerical tools that may be used to simulate fluid flow in fractured media are also presented. Three types of composite models for constant flux tests are investigated. These models are based on the assumption that a fracture system under well test conditions may be represented by two concentric regions, one representing a small number of fractures that dominates flow near the well, and the other representing average conditions farther away from the well. Type curves are presented that can be used to find the flow parameters of these two regions and the extent of the inner concentric region. Several slug test models with different geometric conditions that may be present in fractured media are also investigated. A finite element model that can simulate transient fluid flow in fracture networks is used to study the behavior of various two-dimensional fracture systems under well test conditions. A mesh generator that can be used to model mass and heat flow in a fractured-porous media is presented.
Karasaki, K.
Well test analysis in fractured media
In this study the behavior of fracture systems under well test conditions and methods for analyzing well test data from fractured media are investigated. Several analytical models are developed to be used for analyzing well test data from fractured media. Numerical tools that may be used to simulate fluid flow in fractured media are also presented. Three types of composite models for constant flux tests are investigated. Several slug test models with different geometric conditions that may be present in fractured media are also investigated. A finite element model that can simulate transient fluid flow in fracture networks is used to study the behavior of various two-dimensional fracture systems under well test conditions. A mesh generator that can be used to model mass and heat flow in a fractured-porous media is presented. This model develops an explicit solution in the porous matrix as well as in the discrete fractures. Because the model does not require the assumptions of the conventional double porosity approach, it may be used to simulate cases where double porosity models fail.
Karasaki, K.
??Increasing demand of oil and natural gas and depletion of production from conventional resources accelerate the advancement of technology to economically produce oil and natural� (more)
Siripatrachai, Nithiwat
Gas condensate damage in hydraulically fractured wells
This project is a research into the effect of gas condensate damage in hydraulically fractured wells. It is the result of a problem encountered in producing a low permeability formation from a well in South Texas owned by the El Paso Production Company. The well was producing from a gas condensate reservoir. Questions were raised about whether flowing bottomhole pressure below dewpoint would be appropriate. Condensate damage in the hydraulic fracture was expected to be of significant effect. In the most recent work done by Adedeji Ayoola Adeyeye, this subject was studied when the effects of reservoir depletion were minimized by introduction of an injector well with fluid composition the same as the original reservoir fluid. He also used an infinite conductivity hydraulic fracture along with a linear model as an adequate analogy. He concluded that the skin due to liquid build-up is not enough to prevent lower flowing bottomhole pressures from producing more gas. This current study investigated the condensate damage at the face of the hydraulic fracture in transient and boundary dominated periods when the effects of reservoir depletion are taken into account. As a first step, simulation of liquid flow into the fracture was performed using a 2D 1-phase simulator in order to help us to better understand the results of gas condensate simulation. Then during the research, gas condensate models with various gas compositions were simulated using a commercial simulator (CMG). The results of this research are a step forward in helping to improve the management of gas condensate reservoirs by understanding the mechanics of liquid build-up. It also provides methodology for quantifying the condensate damage that impairs linear flow of gas into the hydraulic fracture.
Reza, Rostami Ravari
A multi-stage flash degaser is incorporated in an energy conversion system having a direct-contact, binary-fluid heat exchanger to remove essentially all of the noncondensable gases from geothermal brine ahead of the direct-contact binary-fluid heat exchanger in order that the heat exchanger and a turbine and condenser of the system can operate at optimal efficiency.
Rapier, P.M.
The Performance of Fractured Horizontal Well in Tight Gas Reservoir
Horizontal wells have been used to increase reservoir recovery, especially in unconventional reservoirs, and hydraulic fracturing has been applied to further extend the contact with the reservoir to increase the efficiency of development. In the past, many models, analytical or numerical, were developed to describe the flow behavior in horizontal wells with fractures. Source solution is one of the analytical/semi-analytical approaches. To solve fractured well problems, source methods were advanced from point sources to volumetric source, and pressure change inside fractures was considered in the volumetric source method. This study aims at developing a method that can predict horizontal well performance and the model can also be applied to horizontal wells with multiple fractures in complex natural fracture networks. The method solves the problem by superposing a series of slab sources under transient or pseudosteady-state flow conditions. The principle of the method comprises the calculation of semi-analytical response of a rectilinear reservoir with closed outer boundaries. A statistically assigned fracture network is used in the study to represent natural fractures based on the spacing between fractures and fracture geometry. The multiple dominating hydraulic fractures are then added to the natural fracture system to build the physical model of the problem. Each of the hydraulic fractures is connected to the horizontal wellbore, and the natural fractures are connected to the hydraulic fractures through the network description. Each fracture, natural or hydraulically induced, is treated as a series of slab sources. The analytical solution of superposed slab sources provides the base of the approach, and the overall flow from each fracture and the effect between the fractures are modeled by applying superposition principle to all of the fractures. It is assumed that hydraulic fractures are the main fractures that connect with the wellbore and the natural fractures are branching fractures which only connect with the main fractures. The fluid inside of the branch fractures flows into the main fractures, and the fluid of the main fracture from both the reservoir and the branch fractures flows to the wellbore. Predicting well performance in a complex fracture network system is extremely challenged. The statistical nature of natural fracture networks changes the flow characteristic from that of a single linear fracture. Simply using the single fracture model for individual fracture, and then adding the flow from each fracture for the network could introduce significant error. This study provides a semi-analytical approach to estimate well performance in a complex fracture network system.
Lin, Jiajing
Gas condensate damage in hydraulically fractured wells
This project is a research into the effect of gas condensate damage in hydraulically fractured wells. It is the result of a problem encountered in producing a low permeability formation from a well in South Texas owned by the El Paso Production Company. The well was producing a gas condensate reservoir and questions were raised about how much drop in flowing bottomhole pressure below dewpoint would be appropriate. Condensate damage in the hydraulic fracture was expected to be of significant effect. Previous attempts to answer these questions have been from the perspective of a radial model. Condensate builds up in the reservoir as the reservoir pressure drops below the dewpoint pressure. As a result, the gas moving to the wellbore becomes leaner. With respect to the study by El-Banbi and McCain, the gas production rate may stabilize, or possibly increase, after the period of initial decline. This is controlled primarily by the condensate saturation near the wellbore. This current work has a totally different approach. The effects of reservoir depletion are minimized by introduction of an injector well with fluid composition the same as the original reservoir fluid. It also assumes an infinite conductivity hydraulic fracture and uses a linear model. During the research, gas condensate simulations were performed using a commercial simulator (CMG). The results of this research are a step forward in helping to improve the management of gas condensate reservoirs by understanding the mechanics of liquid build-up. It also provides methodology for quantifying the condensate damage that impairs linear flow of gas into the hydraulic fracture.
Adeyeye, Adedeji Ayoola
A multi-stage flash degaser (18) is incorporated in an energy conversion system (10) having a direct-contact, binary-fluid heat exchanger to remove essentially all of the noncondensable gases from geothermal brine ahead of the direct-contact binary-fluid heat exchanger (22) in order that the heat exchanger (22) and a turbine (48) and condenser (32) of the system (10) can operate at optimal efficiency.
Rapier, Pascal M. (Richmond, CA)
Catalytic multi-stage liquefaction (CMSL)
Under contract with the U.S. Department of Energy, Hydrocarbon Technologies, Inc. has conducted a series of eleven catalytic, multi-stage, liquefaction (CMSL) bench scale runs between February, 1991, and September, 1995. The purpose of these runs was to investigate novel approaches to liquefaction relating to feedstocks, hydrogen source, improved catalysts as well as processing variables, all of which are designed to lower the cost of producing coal-derived liquid products. This report summarizes the technical assessment of these runs, and in particular the evaluation of the economic impact of the results.
Comolli, A.G.; Ganguli, P.; Karolkiewicz, W.F.; Lee, T.L.K.; Pradhan, V.R.; Popper, G.A.; Smith, T.; Stalzer, R.
Well fracturing method using liquefied gas as fracturing fluid
A method is described for fracturing an oil well or gas well with a mixture of liquid carbon dioxide and liquid petroleum gas. The objective is to be able to inject the liquid into the well bore at a relatively high pumping rate without causing the liquid to boil. Prior to injection, both the liquid CO/sub 2/ and the LPG are held in separate supply tanks at a temperature and pressure at which the liquid phase will not boil. The temperature of the LPG is substantially higher than the liquid CO/sub 2/. During the pumping operation, part of the liquid CO/sub 2/ and all of the LPG are fed through a heat exchanger. In the exchanger, the amount of heat transferred from the LPG to the liquid CO/sub 2/ is enough to vaporize the liquid. The CO/sub 2/ vapor is then circulated back into the CO/sub 2/ tank. The recycled vapor thus maintains the liquid-vapor phase in the tank at equilibrium, so that the liquid will not boil at the desired pumping rate. (4 claims)
Zingg, W.M.; Grassman, D.D.
Multi-stage Cascaded Stirling Refrigerator
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have developed a multi-stage refrigerator, designed to recapture and utilize the acoustic energy that would ordinarily be wasted in traditional Stirling configurations. Available...
Optimizing fracture stimulation using treatment-well tiltmeters and integrated fracture modeling
Science Conference Proceedings (OSTI)
This paper covers the optimization of hydraulic fracture treatments in a new coalbed methane (CBM) reservoir in Wyoming. A multiwell pilot project was conducted in the Copper Ridge (CR) field to assess future development potential. Hydraulic fracture mapping was successfully performed with treatment-well tiltmeters on six wells including the first-ever used on propped treatments. The mapped fracture height was then used to calibrate the fracture model, perform on-site fracture-design changes, and optimize future fracture treatments. This paper shows how early use of fracture diagnostics can assist in the development of a new reservoir.
Mayerhofer, M.; Stutz, L.; Davis, E.; Wolhart, S. [Pinnacle Technology Houston, Houston, TX (United States)
In this work, I present the development of analytical solutions in the Laplace domain for a fully-penetrating, horizontal well producing at a constant flow rate or constant wellbore pressure in the center of a composite, cylindrical reservoir system with an impermeable outer boundary. The composite reservoir consists of two regions. The cylindrical region closest to the wellbore is stimulated, and the permeability within this region follows a power-law function of the radial distance from the wellbore. The unstimulated outer region has homogeneous reservoir properties. The current norm for successful stimulation of low permeability reservoir rocks is multi-stage hydraulic fracturing. The process of hydraulic fracturing creates thin, high permeability fractures that propagate deep into the reservoir, increasing the area of the rock matrix that is exposed to this low-resistance flow pathway. The large surface area of the high conductivity fracture is what makes hydraulic fracturing so successful. Unfortunately, hydraulic fracturing is often encumbered by problems such as high capital costs and a need for large volumes of water. Therefore, I investigate a new stimulation concept based upon the alteration of the permeability of a large volume around the producing well assembly from its original regime to that following a power-law function. I evaluate the effectiveness of the new concept by comparing it to conventional multi-stage hydraulic fracturing. The results of this investigation show that the power-law permeability reservoir (PPR) has a performance advantage over the multi-fractured horizontal treatment (MFH) only when the fracture conductivity and fracture half-length are small. Most importantly, the results demonstrate that the PPR can provide respectable flow rates and recovery factors, thus making it a viable stimulation concept for ultra-low permeability reservoirs, especially under conditions that may not be conducive to a conventional MHF treatment.
Broussard, Ryan Sawyer
A New Parameter Identification Method for Hydraulic Fractured Gas Wells
Science Conference Proceedings (OSTI)
The relaxation search algorithm to identify the parameters of hydraulic fractured gas wells is developed in this paper based on the inductive matrix. According to the optimization theory and parallel computation method, the parameters to be identified ... Keywords: Gas Wells, hydraulic fracturing, formation parameters, parameter identification, historic fitting
Li Tiejun; Guo Dali; Min Chao
Transient and Pseudosteady-State Productivity of Hydraulically Fractured Well
Numerical simulation method is used in this work to solve the problem of transient and pseudosteady-state flow of fluid in a rectangular reservoir with impermeable boundaries. Development and validation of the numerical solution for various well-fracture configurations are the main objectives of this research. The specific case of horizontal well intersected by multiple transverse fractures is the focus of the investigation. The solutions for different operating conditions, constant rate and constant pressure, are represented in the form of transient � peudosteady-state productivity indices. The numerical simulator is validated by comparing results to known analytical solution for radial flow, existing models of productivity for vertical well intersected by vertical fracture, and also with published tables of shape factors. Numerical simulation is a powerful tool to predict well performance. The complexities of well-fracture configurations can be modeled in a truly 3-dimensional system and the pressure and productivity responses for all of the flow regimes can be computed efficiently, enabling optimization of the well-fracture system.
Lumban Gaol, Ardhi
Massive hydraulic fracture of Fenton Hill HDR Well EE-3
Subsequent to a 5.6 million gallon massive hydraulic fracturing (MHF) experiment in Fenton Hill Hot Dry Rock (HDR) Well EE-2, a 2 million gallon MHF was planned for Well EE-3. Although hydraulic communication between wells EE-2 and EE-3 was not established during the initial MHF, a large reservoir was created around EE-2 which seemed to be in proximity with EE-3. The objective of this 2nd MHF was two-fold, to test the reservoir and seismic characteristics of the EE-3 openhole region from 11,390 to 11,770 ft and to drive fractures into the fractured region created earlier by the EE-2 MHF experiment. This paper discusses well repairs to prepare EE-3 for the MHF, the pumping operations, and injection parameters and briefly summarizes seismic results. 2 refs., 6 figs.
Dash, Z.V.; Dreesen, D.S.; Walter, F.; House, L.
Well Stimulation Experiment No. 5 of the Geothermal Reservoir Well Stimulation Program (GRWSP) was performed on March 22, 1981 in Baca 23, located in Union's Redondo Creek Project Area in Sandoval County, New Mexico. The treatment selected was a large hydraulic fracture job designed specifically for, and utilizing frac materials chosen for, the high temperature geothermal environment. The well selection, fracture treatment, experiment evaluation, and summary of the job costs are presented herein.
Not Available
Multi-Stage Multiple-Hypothesis Tracking
While multiple hypothesis tracking (MHT) is widely acknowledged as an effective methodology for multi-target surveillance, there is a challenge to manage effectively a potentially large number of track hypotheses. Advanced single-stage track-while-fuse does not always offer the best processing scheme. We study two instances where multi-stage MHT processing is beneficial�dense target scenarios and complementary-sensor surveillance�and propose two processing schemes for these challenges: track-break-fuse and trackbefore-fuse, respectively. We provide simulation results demonstrating the advantages of these schemes over track-while-fuse. Moregenerally, we argue that multi-stage MHT offers a powerful and flexible paradigm to circumvent limitations in conventional MHT processing.
Stefano Coraluppi; Craig Carthel
Predicting proppant flowback from fracture-stimulated wells
In this thesis, the usefulness and benefits of predicting proppant flowback in the design stage of hydraulic fracturing treatments are evidenced. A new prediction model, as well as a methodology, is proposed in this work. These tools will help companies handle this phenomenon and consequently conduct more efficient fracturing treatments. Currently, proppant flowback is responsible for creating operational complications, increasing expenses and decreasing the productivity of fracture stimulated wells. So far, there have been some empirical approaches that have tried to explain this phenomenon and have helped identify the most important factors that influence it. However, all previous models have drawbacks and do not extend to all practical applications. In this work, the most relevant studies in the area were analyzed in order to clarify the mechanisms that govern the proppant flowback phenomenon. After doing this, the most consistent available features were included in a proposed semi-mechanistic model. This model is considered to be the most rigorous available approach to predict proppant flowback in future treatments. As part of this study, field cases that reported back-production of proppant were analyzed. From this analysis, it was demonstrated that proppant flowback was possible to anticipate. In addition, it was suggested the inclusion of a "Stability Criterion" in the design of future optimum fracturing treatments.
Canon Moreno, Javier Mauricio
Prediction of effects of hydraulic fracturing using reservoir and well flow simulation
Science Conference Proceedings (OSTI)
This paper presents a method to predict and evaluate effects of hydraulic fracturing jobs by using reservoir and well flow numerical simulation. The concept of the method i5 that steam production rate at the operating well head pressure is predicted with different fracture conditions which would be attained by the hydraulic fracturing jobs. Then, the effects of the hydraulic fracturing is evaluated by comparing the predicted steam production rate and that before the hydraulic fracturing. This course of analysis will suggest how large fracture should be created by the fracturing job to attain large enough increase in steam production at the operating condition and the best scheme of the hydraulic fracturing job.
Mineyuki Hanano; Tayuki Kondo
Interpretation of pre- and post-fracturing well tests in a geothermal reservoir
Pre- and post-fracturing well tests in TG-2 well drilled next to the Matsukawa field are interpreted for evaluating effects of a massive hydraulic fracturing treatment. The interpreted data include multiple-step rate tests, a two-step rate test, and falloff tests. Pressure behaviors of massive hydraulic fracturing are matched by a simulator of dynamic fracture option. Fracture parting pressures can be evaluated from the multiple-step rate test data. The multiple-step rates during the massive hydraulic fracturing treatment show that multiple fractures have been induced in sequence. Although the pre-fracturing falloff tests are too short, fracture propagation can be evaluated qualitatively from the falloff data. Interpretation of the falloff test immediately after the MHF suggests that extensive fractures have been created by the MHF, which is verified by simulation. The post-fracturing falloff tests show that the fractures created by the MHF have closed to a great degree.
Arihara, Norio; Fukagawa, Hiroshi; Hyodo, Masami; Abbaszadeh, Maghsood
East Mesa Well 58-30 was selected for two stimulation treatments: a conventional hydraulic fracture in a deep, low permeability interval, and a dendritic fracture in a shallow, high permeability interval of completion. The well selection, pre-stimulation evaluation, fracture treatment design, and post-stimulation evaluation are presented.
Not Available
In situ experiments of geothermal well stimulation using gas fracturing technology
The results of an experimental study of gas fracturing technology for geothermal well stimulation demonstrated that multiple fractures could be created to link water-filled boreholes with existing fractures. The resulting fracture network and fracture interconnections were characterized by mineback as well as flow tests. Commercial oil field fracturing tools were used successfully in these experiments. Simple scaling laws for gas fracturing and a brief discussion of the application of this technique to actual geothermal well stimulation are presented. 10 refs., 42 figs., 4 tabs.
Chu, T.Y.; Warpinski, N.; Jacobson, R.D.
New and Underutilized Technology: Multi-stage Indirect Evaporative Cooling
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
Multi-stage Indirect Evaporative Multi-stage Indirect Evaporative Cooling New and Underutilized Technology: Multi-stage Indirect Evaporative Cooling October 4, 2013 - 4:33pm Addthis The following information outlines key deployment considerations for multi-stage evaporative cooling within the Federal sector. Benefits Multi-stage indirect evaporative cooling is an advanced evaporative cooler that can lower air temperatures without adding moisture. These systems evaporate water in a secondary (or working) airstream, which is discharged in multiple stages. No water or humidity is added to the primary (or product) airstream in the process. Application Multi-stage indirect evaporative cooling is applicable in office, research and development, service, and school applications. Climate and Regional Considerations
Multi-stage Stochastic Linear Programming: Scenarios Versus Events
Manufacturing and service operations management, 4(3):171�207, 2002. [4] A. Berkelaar ... Multi-stage stochastic optimization applied to energy planning.
Multi-Stage Bunch Compressors for the International Linear Collider
150 �m RMS. The multi-stage compressors are somewhat longerthan the single-stage compressor and require additional RFof the NLC Bunch Compressor,� (1999). [4] C. Adolphsen,
Tenenbaum, Peter G.; Raubenheimer, Tor O.; Wolski, Andrzej
Automatic fracture density update using smart well data and artificial neural networks
Science Conference Proceedings (OSTI)
This paper presents a new methodology to continuously update and improve fracture network models. We begin with a hypothetical model whose fracture network parameters and geological information are known. After generating the ''exact'' fracture network ... Keywords: ANN, Fracture networks, Production data, Smart wells, Static data, Static model
A. Al-Anazi; T. Babadagli
not just near the injection well. Note that because thisConcentrations at the injection well increase during thethe fractures away from the injection well is fast, solutes
Cotte, F.P.
Return channel loss reduction in multi-stage centrifugal compressors
This thesis presents concepts for improving the performance of return channels in multi-stage centrifugal compressors. Geometries have been developed to reduce both separation and viscous losses. A number of different ...
Aubry, Anne-Rapha�lle
Multi-stage Stochastic Linear Programming: An Approach by Events
Jul 28, 2008 ... investor problem [4], whose objective consists of obtaining an investment policy which maximizes the utility of the ...... C05-05 from the Spanish government. References ... Multi-stage stochastic optimization applied to energy.
Fracturing fluid high-temperature breaker for improving well performance
Science Conference Proceedings (OSTI)
Oxidative breakers are currently being used in fracturing treatments to reduce polymeric gel damage in high-temperature reservoirs. Dissolved high-temperature oxidative breakers are very reactive at high temperatures (275 to 350 F), typically requiring less than 0.25 lbm/1,000 gal of fluid. Recent introduction of a new nonpersulfate oxidative high-temperature encapsulated breaker (HTEB) provides controlled degradation of the fracturing fluid polymers. Laboratory tests show viscosity reduction and delayed release of active oxidizer breaker. HTEB conductivity data show a two-fold increase in retained permeability at 300 F in a borate-crosslinked fluid system.
McConnell, B.
This thesis presents and develops efficient and effective methodologies for optimal hydraulic fracture design and fracture performance evaluation. These methods incorporate algorithms that simultaneously optimize all of the treatment parameters while accounting for required constraints. Damage effects, such as closure stress, gel damage and non-Darcy flow, are also considered in the optimal design and evaluation algorithms. Two user-friendly program modules, which are active server page (ASP) based, were developed to implement the utility of the methodologies. Case analysis was executed to demonstrate the workflow of the two modules. Finally, to validate the results from the two modules, results were compared to those from a 3D simulation program. The main contributions of this work are: An optimal fracture design methodology called unified fracture design (UFD) is presented and damage effects are considered in the optimal design calculation. As a by-product of UFD, a fracture evaluation methodology is proposed to conduct well stimulation performance evaluation. The approach is based on calculating and comparing the actual dimensionless productivity index of fractured wells with the benchmark which has been developed for optimized production. To implement the fracture design and evaluation methods, two web ASP based user interfaces were developed; one is called Frac Design (Screening), and the other is Frac Evaluation. Both modules are built to hold the following features. o Friendly web ASP based user interface o Minimum user input o Proppant type and mesh size selection o Damage effects consideration options o Convenient on-line help.
Wang, Wenxin
New model for well test analysis in a purely fractured medium
In a porous medium the flow conduits are small and a large number of conduits are connected to the well. For this reason the medium appears to behave like a continuum on the scale of the well test, and volumetric averaging and continuum approximations are justified. On the contrary, in a fractured medium, only a small number of fractures may intersect the pumping well. These particular fractures will be stressed by a large gradient under well test conditions. Consequently, the early time behavior will be dominated by these fractures. The volumetrically averaged permeability does not control flow in the vicinity of an active well. The individual fractures close to the well must be characterized in order to understand the well test behavior especially if the hydraulic parameters of these fractures are significantly different from the average values for the entire system. In the present study, a new analytical model is proposed for well test problems in fracture networks where the matrix is impermeable. The model accounts for the difference in the flow regime around the active well from that of the system as a whole. The analytical solutions are presented in a series of type curves for ranges of dimensionless parameters. The flow properties of the fracture system can be determined by curve matching.
Karasaki, K.; Long, J.C.S.; Witherspoon, P.A.
Analysis Of Macroscopic Fractures In Granite In The Hdr Geothermal Well
Macroscopic Fractures In Granite In The Hdr Geothermal Well Macroscopic Fractures In Granite In The Hdr Geothermal Well Eps-1, Soultz-Sous-Forets, France Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Analysis Of Macroscopic Fractures In Granite In The Hdr Geothermal Well Eps-1, Soultz-Sous-Forets, France Details Activities (0) Areas (0) Regions (0) Abstract: An exhaustive analysis of 3000 macroscopic fractures encountered in the geothermal Hot Dry Rock borehole, EPS-1, located inside the Rhine graben (Soultz-sous-Forets, France), was done on a continuous core section over a depth interval from 1420 to 2230 m: 97% of the macroscopic structures were successfully reorientated with a good degree of confidence by comparison between core and acoustic borehole imagery. Detailed structural analysis of the fracture population indicates that fractures are
This thesis presents a methodology based on Proppant Number approach for optimal fracture treatment design of natural gas wells considering non-Darcy flow effects in the design process. Closure stress is taken into account, by default, because it is the first factor decreasing propped pack permeability at in-situ conditions. Gel damage was also considered in order to evaluate the impact of incorporating more damaging factors on ultimate well performance and optimal geometry. Effective fracture permeability and optimal fracture geometry are calculated through an iterative process. This approach was implemented in a spreadsheet. Non-Darcy flow is described by the ? factor. All ? factor correlations available in the literature were evaluated. It is recommended to use the correlation developed specifically for the given type of proppant and mesh size, if available. Otherwise, the Pursell et al. or the Martins et al. equations are recommended as across the board reliable correlations for predicting non-Darcy flow effects in the propped pack. The proposed methodology was implemented in the design of 11 fracture treatments of 3 natural tight gas wells in South Texas. Results show that optimal fracture design might increase expected production in 9.64 MMscf with respect to design that assumes Darcy flow through the propped pack. The basic finding is that for a given amount of proppant shorter and wider fractures compensate the non-Darcy and/or gel damage effect. Dynamic programming technique was implemented in design of multistage fractures for one of the wells under study for maximizing total gas production. Results show it is a powerful and simple technique for this application. It is recommended to expand its use in multistage fracture designs.
Lopez Hernandez, Henry De Jesus
Span-Wise Mixing in a Multi-Stage Compressor
NLE Websites -- All DOE Office Websites (Extended Search)
SPAN-WISE MIXING IN A MULTI-STAGE COMPRESSOR SPAN-WISE MIXING IN A MULTI-STAGE COMPRESSOR Penn State Bud Lakshminarayana (Cengiz Camci) #036 * Phenomena that have eluded gas turbine designers include the effects of rotor-stator interactions and the physics of mixing of velocity, pressure, temperature and velocity fields. * Compressor tests were conducted in a three stage compressor where deterministic unsteadiness and random fluctuations causing spanwise mixing are realistically replicated . This provided valuable information on rotor stator interaction effects and the nature of the unsteadiness. * Multi-stage compressor energy efficiency improvements are only possible by careful implementation of spanwise mixing models into modern CFD codes (Computational Fluid Dynamics) . *This investigation provided results that are extremely helpful in improving computer
Science Conference Proceedings (OSTI)
This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a propagating turbidite complex through the use of hydraulically-fractured horizontal or high-angle wells. The combination of a horizontal or high-angled well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thininterbedded layers and the well bore.
Mike L. Laue
Science Conference Proceedings (OSTI)
This project attempts to demonstrate the effectiveness of exploiting thin-layered, low energy deposits at the distal end of a protruding turbidite complex through use of hydraulically fractured horizontal of high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than conventional vertical wells while maintaining vertical communication between thin interbedded layers and the well bore.
Mike L. Laue
Economic Recovery of Oil Trapped at Fan Margins Using High Angle Wells Multiple Hydraulic Fractures
This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation will be used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments will be determined, in part, by fracturing an existing test well. Fracture azimuth will be predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well.
Mike L. Laue
Science Conference Proceedings (OSTI)
This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation will be used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments will be determined, in part, by fracturing an existing test well. Fracture azimuth will be predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well.
Mike L. Laue
Based on the information presented in this report, our conclusions regarding the potential for new and novel fracture stimulation technologies to enhance the deliverability of gas storage wells are as follows: New and improved gas storage well revitalization methods have the potential to save industry on the order of $20-25 million per year by mitigating deliverability decline and reducing the need for costly infill wells Fracturing technologies have the potential to fill this role, however operators have historically been reluctant to utilize this approach due to concerns with reservoir seal integrity. With advanced treatment design tools and methods, however, this risk can be minimized. Of the three major fracturing classifications, namely hydraulic, pulse and explosive, two are believed to hold potential to gas storage applications (hydraulic and pulse). Five particular fracturing technologies, namely tip-screenout fracturing, fracturing with liquid carbon dioxide, and fracturing with gaseous nitrogen, which are each hydraulic methods, and propellant and nitrogen pulse fracturing, which are both pulse methods, are believed to hold potential for gas storage applications and will possibly be tested as part of this project. Field evidence suggests that, while traditional well remediation methods such as blowing/washing, mechanical cleaning, etc. do improve well deliverability, wells are still left damaged afterwards, suggesting that considerable room for further deliverability enhancement exists. Limited recent trials of hydraulic fracturing imply that this approach does in fact provide superior deliverability results, but further RD&D work is needed to fully evaluate and demonstrate the benefits and safe application of this as well as other fracture stimulation technologies.
Simulating the Effect of Water on the Fracture System of Shale Gas Wells
It was observed that many hydraulically fractured horizontal shale gas wells exhibit transient linear flow behavior. A half-slope on a type curve represents this transient linear flow behavior. Shale gas wells show a significant skin effect which is uncommon in tight gas wells and masks early time linear behavior. Usually 70-85 percent of frac water is lost in the formation after the hydraulic fracturing job. In this research, a shale gas well was studied and simulated post hydraulic fracturing was modeled to relate the effect of frac water to the early significant skin effect observed in shale gas wells. The hydraulically fractured horizontal shale gas well was described in this work by a linear dual porosity model. The reservoir in this study consisted of a bounded rectangular reservoir with slab matrix blocks draining into neighboring hydraulic fractures and then the hydraulic fractures feed into the horizontal well that fully penetrates the entire rectangular reservoir. Numerical and analytical solutions were acquired before building a 3D 19x19x10 simulation model to verify accuracy. Many tests were conducted on the 3D model to match field water production since initial gas production was matching the analytical solutions before building the 3D simulation model. While some of the scenarios tested were artificial, they were conducted in order to reach a better conceptual understanding of the field. Increasing the water saturation in the formation resulted in increasing water production while lowering gas production. Adding a fractured bottom water layer that leaked into the hydraulic fracture allowed the model to have a good match of water and gas production rates. Modeling trapped frac water around the fracture produced approximately the same amount of water produced by field data, but the gas production was lower. Totally surrounding the fracture with frac water blocked all gas production until some of the water was produced and gas was able to pass through. Finally, trapped frac water around the fracture as combined with bottom water showed the best results match. It was shown that frac water could invade the formation surrounding the hydraulic fracture and could cause formation damage by blocking gas flow. It was also demonstrated that frac water could partially block off gas flow from the reservoir to the wellbore and thus lower the efficiency of the hydraulic fracturing job. It was also demonstrated that frac water affects the square root of time plot. It was proven by simulation that the huge skin at early time could be caused by frac water that invades and gets trapped near the hydraulic fractures due to capillary pressure.
Hamam, Hassan Hasan H.
Science Conference Proceedings (OSTI)
This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore.
Laue, M.L.
Science Conference Proceedings (OSTI)
This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation will be used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments will be determined, in part, by fracturing an existing test well. Fracture azimuth will be predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well. The long radius, near horizontal well was drilled during the first quarter of 1996. Well conditions resulted in the 7 in. production liner sticking approximately 900 ft off bottom. Therefore, a 5 in. production liner was necessary to case this portion of the target formation. Swept-out sand intervals and a poor cement bond behind the 5 in. liner precluded two of the three originally planned hydraulic fracture treatments. As a result, all pay intervals behind the 5 in. liner were perforated and stimulated with a non-acid reactive fluid. Following a short production period, the remaining pay intervals in the well (behind the 7 in. liner) were perforated. The well was returned to production to observe production trends and pressure behavior and assess the need to stimulate the new perforations.
Mike L. Laue
Evidence of Reopened Microfractures in Production Data of Hydraulically Fractured Shale Gas Wells
Frequently a discrepancy is found between the stimulated shale volume (SSV) estimated from production data and the SSV expected from injected water and proppant volume. One possible explanation is the presence of a fracture network, often termed fracture complexity, that may have been opened or reopened during the hydraulic fracturing operation. The main objective of this work is to investigate the role of fracture complexity in resolving the apparent SSV discrepancy and to illustrate whether the presence of reopened natural fracture network can be observed in pressure and production data of shale gas wells producing from two shale formations with different well and reservoir properties. Homogeneous, dual porosity and triple porosity models are investigated. Sensitivity runs based on typical parameters of the Barnett and the Horn River shale are performed. Then the field data from the two shales are matched. Homogeneous models for the two shale formations indicate effective infinite conductivity fractures in the Barnett well and only moderate conductivity fractures in the Horn River shale. Dual porosity models can support effectively infinite conductivity fractures in both shale formations. Dual porosity models indicate that the behavior of the Barnett and Horn River shale formations are different. Even though both shales exhibit apparent bilinear flow behavior the flow behaviors during this trend are different. Evidence of this difference comes from comparing the storativity ratio observed in each case to the storativity ratio estimated from injected fluid volumes during hydraulic fracturing. In the Barnett shale case similar storativity ratios suggest fracture complexity can account for the dual porosity behavior. In the Horn River case, the model based storativity ratio is too large to represent only fluids from hydraulic fracturing and suggests presence of existing shale formation microfractures.
Apiwathanasorn, Sippakorn
A novel technique of recognising multi-stage attack behaviour
Science Conference Proceedings (OSTI)
With the increasing amount of security audit data, management and analysis of it become a critical and challenging issue. Security alerts and threat analysis project (SATA) aims at analysing security events and detecting security threat. In this ... Keywords: attack plan recognition, correlativity, intrusion detection, multi-stage attacks, security alerts, security threats, threat analysis
Li Wang; Yao Li; Zhi-tang Li
Results of stress-oriented and aligned perforating in fracturing deviated wells
This paper reports the first results of stress-oriented and aligned perforation of deviated wells at the Kuparuk River field, Alaska. Preferred perforation alignment and spacing are calculated for each well so the fractures from individual perforations link to produce a single zipper fracture plane along the deviated wellbore. Results of the first application of this technique are presented from the 26-well development of Drillsite 2K. The results from use of three different oriented-casing-gun systems and pertinent data from Drillsite 2K fracture stimulation treatments are discussed. Comparisons to drillsite where nonaligned perforating strategies were used show a significant reduction in perforation friction, enabling the placement of large, more productive fracture treatments. Application of this technique to deviated and vertical wells and its use at Kuparuk on developments after Drillsite 2K are discussed.
Pearson, C.M.; Bond, A.J.; Eck, M.E.; Schmidt, J.H. (Arco Alaska Inc. (US))
GEOCOM, a computer code that provides life cycle cost/benefit analysis of completion technologies applied to geothermal wells, is used to study fracture stimulation techniques. it is estimated that stimulation must increase flow by roughly tons per $100,000 in order to be cost effective. Typically, hydraulic fracturing costs $100,000 to $500,000 per well, and the attempts at stimulation to date have generally not achieved the desired flow increases. The cost effectiveness of hydraulic fracturing is considered for several geothermal reservoirs.
Brown, G.L.
Estimating fracture parameters from p-wave velocity profiles about a geothermal well
The feasibility of locating fracture zones and estimating their crack parameters was examined using an areal well shoot method centered on Utah State Geothermal Well 9-1, Beaver County, Utah. High-resolution travel time measurements were made between a borehole sensor and an array of shot stations distributed radially and azimuthally about the well. Directional velocity behavior in the vicinity of the well was investigated by comparing velocity logs derived from the travel time data. Three fracture zones were identified form the velocity data, corroborating fracture indicators seen in other geophysical logs conducted in Well 9-1. Crack densities and average crack aspect ratios for these fracture zones were estimated using a self-consistent velocity theory (O'Connell and Budiansy 1974). Probable trends of these fracture zones were established from a combination of the data from the more distant shot stations and the results of a gravity survey. The results of this study indicate that the areal well shoot is a potentially powerful tool for the reconnaisance of fracture-controlled fluid and gas reservoirs. Improvements in methodology and hardware could transform it into an operationally viable survey method.
Jenkinson, J.T.; Henyey, T.L.; Sammis, C.G.; Leary, P.C.; McRaney, J.K.
FRACTURE, AND FLUID FLOW ANALYSIS IN WELL 38C-9:AN ENHANCED FRACTURE, AND FLUID FLOW ANALYSIS IN WELL 38C-9:AN ENHANCED GEOTHERMAL SYSTEM IN THE COSO GEOTHERMAL FIELD Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: IN SITU STRESS, FRACTURE, AND FLUID FLOW ANALYSIS IN WELL 38C-9:AN ENHANCED GEOTHERMAL SYSTEM IN THE COSO GEOTHERMAL FIELD Details Activities (2) Areas (1) Regions (0) Abstract: Geoscientists from the Coso Operating Company, EGI-Utah, GeoMechanics International, and the U.S. Geological Survey are cooperating in a multi-year study to develop an Enhanced Geothermal System (EGS) in the Coso Geothermal Field. Key to the creation of an EGS is an understanding of the relationship among natural fracture distribution, fluid flow, and the ambient tectonic stresses that exist within the resource in order to design
In situ stress, fracture, and fluid flow analysis in Well 38C-9: an
In situ stress, fracture, and fluid flow analysis in Well 38C-9: an In situ stress, fracture, and fluid flow analysis in Well 38C-9: an enhanced geothermal system in the Coso geothermal field Jump to: navigation, search OpenEI Reference LibraryAdd to library Conference Paper: In situ stress, fracture, and fluid flow analysis in Well 38C-9: an enhanced geothermal system in the Coso geothermal field Abstract Geoscientists from the Coso Operating Company, EGI-Utah, GeoMechanics International, and the U.S. Geological Survey are cooperating in a multi-year study to develop an Enhanced Geothermal System (EGS) in the Coso Geothermal Field. Key to the creation of an EGS is an understanding of the relationship among natural fracture distribution, fluid flow, and the ambient tectonic stresses that exist within the resource in order to design
Application of the pseudolinear flow model to the pressure transient analysis of fractured wells
The theoretical basis for the pseudolinear flow model is established. It is demonstrated by using an analytical model that the linear flow graph (p vs ..sqrt..t) can be extended to the analysis of pressure data of fractured wells intersected by an intermediate or a high conductivity fracture ((k /SUB f/ b /SUB f/ greater than or equal to 15). It appears that the fracture conductivity effect during the pseudolinear flow period can be handled as a pseudo skin pressure drop which is additive to the pressure drop caused by fluid loss damage. The combination of the pseudolinear flow analysis with other interpretation techniques is illustrated through examples of field cases.
Cinco-Ley, H.; Rodriguez, F.; Samaniego, F.
Candidate Well Selection for the Test of Degradable Biopolymer as Fracturing Fluid
Hydraulic fracturing is a well-established technology of generating highly conductive flow path inside the rock by injecting massive amount of fracturing fluid and proppant with sufficient pressure to break the formation apart. But as the concern for environment and health effects of hydraulic fracturing becomes intense, many efforts are made to replace the conventional fracturing fluid with more environment-friendly materials. The degradable biopolymer is one of the novel materials that is injected in the form of solid pellets containing proppant, degrades in the presence of water to form a viscous gel fluid, leaving no gel residue or harmful material. This work develops a methodology and computer program to determine the best candidate wells for the field test of degradable biopolymer as fracturing fluid. The unique properties of degradable biopolymer is captured in the selection of decision criteria such as bottomhole temperature and treatment volume as well as traditional hydraulic fracturing candidate well selection criteria such as formation permeability, productivity index.
Hwang, Yun Suk
Improvement of tubulars used for fracturing in hot dry rock wells
Completion of hot dry rock wells as it is currently envisioned, requires that hydraulic fracturing be used to develop a heat extraction reservoir and to provide low impedance flow paths between the designated water injection and production wells. Recent fracturing operations at measured depths from 11,400 ft to 15,300 ft at the Fenton Hill Hot Dry Rock Geothermal Test Site have resulted in numerous failures of tubulars caused by the high fracturing pressures, corrosive environment and large treatment volumes at high flow rates. Two new fracturing strings were designed and purchased. Physical and chemical properties exceeding API specifications were demanded and supplied by the manufacturers. These tubulars have performed to design specifications.
Nicholson, R.W.; Dreesen, D.S.; Turner, W.C.
Multi-stage, isothermal CO preferential oxidation reactor
A multi-stage, isothermal, carbon monoxide preferential oxidation (PrOx) reactor comprising a plurality of serially arranged, catalyzed heat exchangers, each separated from the next by a mixing chamber for homogenizing the gases exiting one heat exchanger and entering the next. In a preferred embodiment, at least some of the air used in the PrOx reaction is injected directly into the mixing chamber between the catalyzed heat exchangers.
Skala, Glenn William (Churchville, NY); Brundage, Mark A. (Pittsford, NY); Borup, Rodney Lynn (East Rochester, NY); Pettit, William Henry (Rochester, NY); Stukey, Kevin (W. Henrietta, NY); Hart-Predmore, David James (Rochester, NY); Fairchok, Joel (Alexander, NY)
Multi-stage depressed collector for small orbit gyrotrons
A multi-stage depressed collector for receiving energy from a small orbit gyrating electron beam employs a plurality of electrodes at different potentials for sorting the individual electrons on the basis of their total energy level. Magnetic field generating coils, for producing magnetic fields and magnetic iron for magnetic field shaping produce adiabatic and controlled non-adiabatic transitions of the incident electron beam to further facilitate the sorting.
Singh, Amarjit (Greenbelt, MD); Ives, R. Lawrence (Saratoga, CA); Schumacher, Richard V. (Campbell, CA); Mizuhara, Yosuke M. (Palo Alto, CA)
Gas storage wells are prone to continued deliverability loss at a reported average rate of 5% per annum (in the U.S.). This is a result of formation damage due to the introduction of foreign materials during gas injection, scale deposition and/or fines mobilization during gas withdrawal, and even the formation and growth of bacteria. As a means to bypass this damage and sustain/enhance well deliverability, several new and novel fracture stimulation technologies were tested in gas storage fields across the U.S. as part of a joint U.S. Department of Energy and Gas Research Institute R&D program. These new technologies include tip-screenout fracturing, hydraulic fracturing with liquid CO{sub 2} and proppant, extreme overbalance fracturing, and high-energy gas fracturing. Each of these technologies in some way address concerns with fracturing on the part of gas storage operators, such as fracture height growth, high permeability formations, and fluid sensitivity. Given the historical operator concerns over hydraulic fracturing in gas storage wells, plus the many other unique characteristics and resulting stimulation requirements of gas storage reservoirs (which are described later), the specific objective of this project was to identify new and novel fracture stimulation technologies that directly address these concerns and requirements, and to demonstrate/test their potential application in gas storage wells in various reservoir settings across the country. To compare these new methods to current industry deliverability enhancement norms in a consistent manner, their application was evaluated on a cost per unit of added deliverability basis, using typical non-fracturing well remediation methods as the benchmark and considering both short-term and long-term deliverability enhancement results. Based on the success (or lack thereof) of the various fracture stimulation technologies investigated, guidelines for their application, design and implementation have been developed. A final research objective was to effectively deploy the knowledge and experience gained from the project to the gas storage industry at-large.
Science Conference Proceedings (OSTI)
The ability to reliably predict flow and transport in fractured porous rock is an essential condition for performance evaluation of geologic (underground) nuclear waste repositories. In this report, a suite of programs (TRIPOLY code) for calculating and analyzing flow and transport in two-dimensional fracture-matrix systems is used to model single-well injection-withdrawal (SWIW) tracer tests. The SWIW test, a tracer test using one well, is proposed as a useful means of collecting data for site characterization, as well as estimating parameters relevant to tracer diffusion and sorption. After some specific code adaptations, we numerically generated a complex fracture-matrix system for computation of steady-state flow and tracer advection and dispersion in the fracture network, along with solute exchange processes between the fractures and the porous matrix. We then conducted simulations for a hypothetical but workable SWIW test design and completed parameter sensitivity studies on three physical parameters of the rock matrix - namely porosity, diffusion coefficient, and retardation coefficient - in order to investigate their impact on the fracture-matrix solute exchange process. Hydraulic fracturing, or hydrofracking, is also modeled in this study, in two different ways: (1) by increasing the hydraulic aperture for flow in existing fractures and (2) by adding a new set of fractures to the field. The results of all these different tests are analyzed by studying the population of matrix blocks, the tracer spatial distribution, and the breakthrough curves (BTCs) obtained, while performing mass-balance checks and being careful to avoid some numerical mistakes that could occur. This study clearly demonstrates the importance of matrix effects in the solute transport process, with the sensitivity studies illustrating the increased importance of the matrix in providing a retardation mechanism for radionuclides as matrix porosity, diffusion coefficient, or retardation coefficient increase. Interestingly, model results before and after hydrofracking are insensitive to adding more fractures, while slightly more sensitive to aperture increase, making SWIW tests a possible means of discriminating between these two potential hydrofracking effects. Finally, we investigate the possibility of inferring relevant information regarding the fracture-matrix system physical parameters from the BTCs obtained during SWIW testing.
Cotte, F.P.; Doughty, C.; Birkholzer, J.
The Cost Effectiveness of Fracture Stimulation in Increasing the Flow from Geothermal Wells
The cost effectiveness of fracture stimulation at The Geysers, the Imperial Valley, and other geothermal resource areas in the United States vas studied using GEOCOM, a computer code for analyzing the impact of completion activities on the life-cycle costs of geothermal wells. Technologies for fracturing the reservoir near the wellbore involve the creation of a pressure pulse in the wellbore by means of either hydraulic or explosive force. The cost of a single fracture stimulation job can vary from $50,000 to over $500,000, with a typical cost of around $300,000. The code shows that additional flow achieved by fracture stimulation must exceed 10,000 pounds per hour for each $100,000 invested in stimulation in order for a fracture treatment to be cost effective. In some reservoirs, this additional flow must be as great as 30,000 pounds per hour. The cost effectiveness of fracturing has not yet been demonstrated in the field. The Geothermal Well Stimulation Program achieved an overall average of about 10,000 pounds per hour for each $100,000 invested.
Brown, Gerald L.
Modelling and analysis of multi-stage systems of mistuned bladed disks
Science Conference Proceedings (OSTI)
A stochastic reduced-order modelling technique for multi-stage mistuned bladed disks assemblies is proposed. In a perturbation framework, the base-line reduced-order model is built using multi-stage cyclic symmetry modelling approach. Uncertainties are ... Keywords: Cyclic symmetry, Mistuning, Multi-stage, Reduce-order models, Uncertainties
Denis Laxalde; Christophe Pierre
A study of the effects of well and fracture design in a typical Marcellus shale well.
??The problem with typical Marcellus shale wells is the lack of information that has beenaccumulated and the amount of information that is commercially available to� (more)
Schweitzer, Ross T.
Application of the pseudolinear-flow model to the pressure-transient analysis of fractured wells
The theoretical basis for the pseudolinear-flow model is established. In this paper it is demonstrated by use of an analytical model that the linear-flow graph (rho vs. {Lambda}tau) can be extended to the analysis of pressure data of fractured wells intersected by an intermediate- or high-conductivity fracture (C/sub fD/ > 5{pi}). It appears that the fracture-conductivity effect during the pseudolinear-flow period can be handled as pseudoskin pressure drop that adds to the pressure drop caused by fluid-loss damage. The combination of the pseudolinear-flow analysis with other interpretation techniques is illustrated through examples of field cases.
Cinco-Ley, H.; Samanlego, V.F. (Univ. of Mexico/Pemex (MX)); Rodriguez, F. (Univ. of Mexico/IMP (MX))
Science Conference Proceedings (OSTI)
This project attempts to demonstrate the effectivensss of exploiting thin-layered, low energy deposits at the distal margin of a propagating turbinite complex through u se of hydraulically fractgured horizontal of high-angle wells. TGhe combinaton of a horizontal or high-angle weoo and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore.
Mike L. Laue
Multi-stage fuel cell system method and apparatus
A high efficiency, multi-stage fuel cell system method and apparatus is provided. The fuel cell system is comprised of multiple fuel cell stages, whereby the temperatures of the fuel and oxidant gas streams and the percentage of fuel consumed in each stage are controlled to optimize fuel cell system efficiency. The stages are connected in a serial, flow-through arrangement such that the oxidant gas and fuel gas flowing through an upstream stage is conducted directly into the next adjacent downstream stage. The fuel cell stages are further arranged such that unspent fuel and oxidant laden gases too hot to continue within an upstream stage because of material constraints are conducted into a subsequent downstream stage which comprises a similar cell configuration, however, which is constructed from materials having a higher heat tolerance and designed to meet higher thermal demands. In addition, fuel is underutilized in each stage, resulting in a higher overall fuel cell system efficiency.
George, Thomas J. (Morgantown, WV); Smith, William C. (Morgantown, WV)
Multi-stage fuel cell system method and apparatus
A high efficiency, multi-stage fuel cell system method and apparatus is provided. The fuel cell system is comprised of multiple fuel cell stages, whereby the temperatures of the fuel and oxidant gas streams and the percentage of fuel consumed in each stage are controlled to optimize fuel cell system efficiency. The stages are connected in a serial, flow-through arrangement such that the oxidant gas and fuel gas flowing through an upstream stage is conducted directly into the next adjacent downstream stage. The fuel cell stages are further arranged such that unspent fuel and oxidant laden gases too hot to continue within an upstream stage because of material constraints are conducted into a subsequent downstream stage which comprises a similar cell configuration, however, which is constructed from materials having a higher heat tolerance and designed to meet higher thermal demands. In addition, fuel is underutilized in each stage, resulting in a higher overall fuel cell system efficiency.
George, Thomas J.; Smith, William C.
The Implications and Flow Behavior of the Hydraulically Fractured Wells in Shale Gas Formation
Shale gas formations are known to have low permeability. This low permeability can be as low as 100 nano darcies. Without stimulating wells drilled in the shale gas formations, it is hard to produce them at an economic rate. One of the stimulating approaches is by drilling horizontal wells and hydraulically fracturing the formation. Once the formation is fractured, different flow patterns will occur. The dominant flow regime observed in the shale gas formation is the linear flow or the transient drainage from the formation matrix toward the hydraulic fracture. This flow could extend up to years of production and it can be identified by half slop on the log-log plot of the gas rate against time. It could be utilized to evaluate the hydraulic fracture surface area and eventually evaluate the effectiveness of the completion job. Different models from the literature can be used to evaluate the completion job. One of the models used in this work assumes a rectangular reservoir with a slab shaped matrix between each two hydraulic fractures. From this model, there are at least five flow regions and the two regions discussed are the Region 2 in which bilinear flow occurs as a result of simultaneous drainage form the matrix and hydraulic fracture. The other is Region 4 which results from transient matrix drainage which could extend up to many years. The Barnett shale production data will be utilized throughout this work to show sample of the calculations. This first part of this work will evaluate the field data used in this study following a systematic procedure explained in Chapter III. This part reviews the historical production, reservoir and fluid data and well completion records available for the wells being analyzed. It will also check for data correlations from the data available and explain abnormal flow behaviors that might occur utilizing the field production data. It will explain why some wells might not fit into each model. This will be followed by a preliminary diagnosis, in which flow regimes will be identified, unclear data will be filtered, and interference and liquid loading data will be pointed. After completing the data evaluation, this work will evaluate and compare the different methods available in the literature in order to decide which method will best fit to analyze the production data from the Barnett shale. Formation properties and the original gas in place will be evaluated and compared for different methods.
Almarzooq, Anas Mohammadali S.
Application of a design optimization strategy to multi-stage compressor matching.
??A major challenge in the design of multi-stage compressors is the matching of stages to enable stable operation over a large range of mass flows� (more)
Bert, J�r�me
Economic Recovery of Oil Trapped at Fan Margins Using Hig Angle Wells Multiple Hydraulic Fractures
Science Conference Proceedings (OSTI)
The Yowlumne field is a giant field in the southern San Joaquin basin, Kern County, California. It is a deep (13,000 ft) waterflood operation that produces from the Miocene- aged Stevens Sand. The reservoir is interpreted as a layered, fan-shaped, prograding turbidite complex containing several lobe-shaped sand bodies that represent distinct flow units. A high ultimate recovery factor is expected, yet significant quantities of undrained oil remain at the fan margins. The fan margins are not economic to develop using vertical wells because of thinning pay, deteriorating rock quality, and depth. This project attempts to demonstrate the effectiveness of exploiting the northeast distal fan margin through the use of a high- angle well completed with multiple hydraulic- fracture treatments. A high-angle well offers greater pay exposure than can be achieved with a vertical well. Hydraulic-fracture treatments will establish vertical communication between thin interbedded layers and the wellbore. The equivalent production rate and reserves of three vertical wells are anticipated at a cost of approximately two vertical wells. The near-horizontal well penetrated the Yowlumne sand; a Stevens sand equivalent, in the distal fan margin in the northeast area of the field. The well was drilled in a predominately westerly direction towards the interior of the field, in the direction of improving rock quality. Drilling and completion operations proved to be very challenging, leading to a number of adjustments to original plans. Hole conditions resulted in obtaining less core material than desired and setting intermediate casing 1200 ft too high. The 7 in. production liner stuck 1000 ft off bottom, requiring a 5 in. liner to be run the rest of the way. The cement job on the 5 in. liner resulted in a very poor bond, which precluded one of three hydraulic fracture treatments originally planned for the well. Openhole logs confirmed most expectations going into the project about basic rock properties: the formation was shaly with low porosities, and water saturations were in line with expectations, including the presence of some intervals swept out by the waterflood. High water saturations at the bottom of the well eliminated one of the originally planned hydraulic fracture treatments. Although porosities proved to be low, they were more uniform across the formation than expected. Permeabilities of the various intervals continue to be evaluated, but appear to be better than expected from the porosity log model derived in Budget Period One. The well was perforated in all pay sections behind the 5 in. liner. Production rates and phases agree nicely with log calculations, fractional flow calculations, and an analytical technique used to predict the rate performance of the well.
Laue, M.L.
Multi-Stage Supercompaction Of Large Low-Level Waste Components
This paper demonstrates that multi-stage compaction (supercompaction) (high-force compaction) has an important role to play in treating metallic LLW. A specialized shear/compactor can produce significant labor and burial cost savings, as well as better operational safety and environmental protection. A case study is the supercompaction facility presently nearing completion at the DOE East Tennessee Technology Park--ETTP--(formerly, the K-25 Gaseous Diffusion Plant) in Oak Ridge. The facility will initially process some 63,000 tons of mainly metallic materials arising from the D&D clean-up project presently being undertaken by BNFL Inc. for the DOE. These materials cannot be economically recycled and prior to burial disposal will be supercompacted with up to 7:1 volume reduction. The paper will confirm progress toward facility handover to production in October 2000. 1. INTRODUCTION Supercompaction is a loosely defined term, and this paper starts by offering a definition, and by re...
Martin Cottam Bsc; Martin Cottam; C Eng
One of the critical steps in developing a hot dry rock geothermal system is the creation of flow paths through the rock between two wellbores. To date, circulation systems have only been created by drilling one wellbore, hydraulically fracturing the well (which induces microearthquakes), locating the microearthquakes and then drilling a second wellbore through the zone of seismicity. A technique for analyzing the pattern of seismicity to determine where fracture planes are located in the seismically active region has recently been developed. This allows us to distinguish portions of the seismically active volume which are most likely to contain significant flow paths. We applied this technique to seismic data collected during a massive hydraulic fracturing (MHF) treatment and found that the fracture planes determined by the seismic method are confirmed by borehole temperature and caliper logs which indicate where permeable fractures and/or zones of weakness intersect the wellbores. A geometric model based on these planes and well log data has enhanced our understanding of the reservoir flow paths created by fracturing and is consistent with results obtained during production testing of the reservoir.
Dreesen, D.; Malzahn, M.; Fehler, M.; Dash, Z.
Application of a design optimization strategy to multi-stage compressor matching
A major challenge in the design of multi-stage compressors is the matching of stages to enable stable operation over a large range of mass flows and operating conditions. Particularly in turbofan low-pressure compressors, ...
Bert, J�r�me
Many if not most of the core problems studied in operations management fall into the category of multi-stage stochastic optimization models, whereby one considers multiple, often correlated decisions to optimize a particular ...
Shi, Cong, Ph.D. Massachusetts Institute of Technology
Massive hydraulic fracturing experiment No. 1 Home Federal well, Uintah County, Utah
Two massive hydraulic fracturing experiments were performed on two separate gas-bearing intervals of Mesaverde sandstones in the No. 1 Home Federal well located in Uintah County, Utah. Water-base gel carrying sand proppant was used as the frac medium and the limited entry technique was used for injection. The first experiment was carried out on an interval containing 112 ft of net pay between 10,014 and 10,202 ft. Pre-frac production capacity was estimated to be 60+ MCF/D. Post-frac production capacity was significantly less, presumably attributable to a limited lateral extent of inherent formation permeability. The second experiment was carried out on an interval containing 85 ft of net pay between 7826 and 9437 ft. Pre-frac production capacity of 33 MCF/D was increased by MHF to an initial 500 MCF/D and to a relatively stabilized 155 MCF/D within four months following the treatment.
Boardman, C.R.
This study evaluates compatibility of a self-degradable temporary fracture sealer with the drilling mud and plugging and self-degrading performance of different fibers to be used in combination with the sealer. The sodium silicate-activated slag/Class C fly ash (SSASC) cementitious sealer must plug fractures at 85oC to allow continuous well drilling and it must degrade and leave the fractures open for water at later times when exposed to temperatures above 200oC. The sealer showed good compatibility with the mud. Even the blend of 80/20 vol.% of sealer/mud reached a compressive strength of more than 2000 psi set as one of the material criteria, mostly due to the additional activation of the slag and Class C fly ash by the alkaline ingredient present in the drilling fluid. In contrast, the drilling fluid was detrimental to the compressive strength development in conventional Class G well cement, so that it failed to meet this criterion. Among several organic fibers tested both polyvinyl alcohol (PVA)-and nylon-based fibers showed adequate plugging of the sealer in slot nozzles of 1-in. wide x 6-in. long x 0.08 in. and 0.24 in. high under pressures up to 700 psi. PVA fibers displayed better compressive toughness and self-degrading properties than nylon. The compressive toughness of sealers made by adding 1.0 wt% 6 mm-length PVA and 0.5 wt% 19 mm-length PVA was 9.5-fold higher than that of a non-bridged sealer. One factor governing the development of such high toughness was an excellent adherence of PVA to the SSASC cement. The alkali-catalyzed self-decomposition of PVA at 200�C led to the morphological transformation of the material from a fibrous structure to a microscale flake-like structure that helped the desirable conversion of the sealer into small fragments. In contrast, nylon�s decomposition provided a reticular network structure in the self-degraded sealer resulting in bigger fragments compared against the sealer with PVA. The PVA fiber has a high potential as a self-decomposable bridging additive in the SSASC cement sealer.
Sugama T.; Pyatina, T.; Gill, S.; Kisslinger, K.; Iverson, B.; Bour, D.
The Development of Optimization System of Fracturing about CBM's Vertical Wells
Science Conference Proceedings (OSTI)
The reasonable fracturing pumping parameters are the keys to improve the conductivity of the coal reservoir, save costs and improve gas production. According to the characteristics of coal reservoir, a coal reservoir propping agent evaluation system ... Keywords: coalbed methane, fracturing, optimization system, permeability Introduction
Xiaoming Ni; Peng Chen
Pressure oscillations caused by momentum on shut in of a high rate well in a fractured formation
Pressure transient testing techniques are an important part of reservoir and production testing procedures. These techniques are frequently used to determine practical information about underground reservoirs such as the permeability, porosity, liquid content, reservoir and liquid discontinuities and other related data. This information is valuable in helping to analyze, improve and forecast reservoir performance. This report is concerned with developing models for pressure transient well testing in high permeability, high flow rate, naturally fractured reservoirs. In the present work, a study was made of the effects of liquid inertia in the fractures and the wellbore on the pressure response obtained during a well test. The effects of turbulent flow and multi-phase flow effects such as gravitational segregation or anisotropic porous media effects were not considered. The scope of the study was limited to studying inertial effects on the pressure response of a fractured reservoir.
Bhatnagar, S.
Non-darcy flow behavior mean high-flux injection wells in porous and fractured formations
Phase and Multiphase Non-Darcy Flow in Porous and FracturedFormulation A multiphase system in a porous or fracturedand multiphase non-Darcy flow in multidimensional porous and
Wu, Yu-Shu
The Steamboat Hills Geothermal Field in northwestern Nevada, about 15 km south of Reno, is a shallow (150m to 825m) moderate temperature (155 C to 168 C) liquid-dominated geothermal reservoir situated in highly-fractured granodiorite. Three injection wells were drilled and completed in granodiorite to dispose of spent geothermal fluids from the Steamboat II and III power plants (a 30 MW air-cooled binary-type facility). Injection wells were targeted to depths below 300m to inject spent fluids below producing fractures. First, quasi-static downhole pressure-temperature-spinner (PTS) logs were obtained. Then, the three wells were injection-tested using fluids between 80 C and 106 C at rates from 70 kg/s to 200 kg/s. PTS logs were run both up and down the wells during these injection tests. These PTS surveys have delineated the subsurface fracture zones which will accept fluid. The relative injectivity of the wells was also established. Shut-in interzonal flow within the wells was identified and characterized.
Goranson, Colin; Combs, Jim
Single-well injection-withdrawal (SWIW) tracer tests involve injection of traced fluid and subsequent tracer recovery from the same well, usually with some quiescent time between the injection and withdrawal periods. SWIW are insensitive to variations in advective processes that arise from formation heterogeneities, because upon withdrawal, fluid parcels tend to retrace the paths taken during injection. However, SWIW are sensitive to diffusive processes, such as diffusive exchange of conservative or reactive solutes between fractures and rock matrix. This paper focuses on SWIW tests in which temperature itself is used as a tracer. Numerical simulations demonstrate the sensitivity of temperature returns to fracture-matrix interaction. We consider thermal SWIW response to the two primary reservoir improvements targeted with stimulation, (1) making additional fractures accessible to injected fluids, and (2) increasing the aperture and permeability of pre-existing fractures. It is found that temperature returns in SWIW tests are insensitive to (2), while providing a strong signal of more rapid temperature recovery during the withdrawal phase for (1).
Pruess, K.; Doughty, C.
Multi-stage programming with functors and monads: Eliminating abstraction overhead from generic code
Science Conference Proceedings (OSTI)
We use multi-stage programming, monads and Ocaml's advanced module system to demonstrate how to eliminate all abstraction overhead from generic programs, while avoiding any inspection of the resulting code. We demonstrate this clearly with Gaussian Elimination ... Keywords: Functor, Generative, Genericity, Linear algebra, MetaOCaml, Staging, Symbolic
Jacques Carette; Oleg Kiselyov
This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation will be used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments will be determined, in part, by fracturing an existing test well. Fracture azimuth will be predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well. The long radius, near horizontal well has been drilled. After pumping a remedial cement squeeze, all pay behind the 5 in. liner was perforated and stimulated. Once wellwork is complete for the existing perforations, a hydraulic fracture treatment will be pumped through a short interval of clustered perforations in the 7 in. liner. Following this frac, all pay behind the 7 in. liner will be perforated and completion operations will be final.
Laue, M.L.
This work of well performance modeling is focused on solving problems of transient and pseudo-steady state fluid flow in a rectilinear closed boundaries reservoir. This model has been applied to predict and to optimize gas production from a horizontal well intercepted by multiple transverse fractures in a bounded reservoir, and it also provides well-testing solutions. The well performance model is designed to provide enhanced efficiency with the same reliability for pressure transient analysis, and well performance prediction, especially in complex well fracture configuration. The principle is to simplify the calculation of the pressure response to an instantaneous withdraw, which happens in other fractures, within a shorter computational time. This pressure response is substituted with the interaction between the two whole fractures. This method is validated through comparison to results of rigorous Distributed Volumetric Sources (DVS) method in simple symmetric fracture configuration, and to results of field production data for complex well/fracture configuration of a tight gas reservoir. The results show a good agreement in both ways. This model indicates the capability to handle the situations, such as: various well drainages, asymmetry of the fracture wings, and curved horizontal well. The advantage of this well performance model is to provide faster processing - reducing the computational time as the number of fractures increase. Also, this approach is able to be applied as an optimization and screening tool to obtain the best fracture configurations for reservoir development of economically marginal fields, in terms of the number and dimensions of fractures per well, also with external economic and operational constraints.
Fan, Diangeng
Hydraulic fracturing has recently been the completion of choice for most tight gas bearing formations. It has proven successful to produce these formations in a commercial manner. However, some considerations have to be taken into account to design an optimum stimulation treatment that leads to the maximum possible productivity. These considerations include, but not limited to, non-Darcy flow and multiphase flow effects inside the fracture. These effects reduce the fracture conductivity significantly. Failing to account for that results in overestimating the deliverability of the well and, consequently, to designing a fracture treatment that is not optimum. In this work a thorough investigation of non-Darcy flow and multi-phase flow effects on the productivity of hydraulically fractured wells is conducted and an optimum fracture design is proposed for a tight gas formation in south Texas using the Unified Fracture Design (UFD) Technique to compensate for the mentioned effects by calculating the effective fracture permeability in an iterative way. Incorporating non-Darcy effects results in an optimum fracture that is shorter and wider than the fracture when only Darcy calculations are considered. That leads to a loss of production of 5, 18 percent due to dry and multiphase non-Darcy flow effects respectively. A comparison between the UFD and 3D simulators is also done to point out the differences in terms of methodology and results. Since UFD incorporated the maximum dimensionless productivity index in the fracture dimensions design, unlike 3D simulators, it can be concluded that using UFD to design the fracture treatment and then use the most important fracture parameters outputs (half length and CfDopt) as inputs in the simulators is a recommended approach.
Alarbi, Nasraldin Abdulslam A.
Testing for Estimating Heat Transfer Area in FracturedFRACTURE-MATRIX HEAT TRANSFER AREA Karsten Pruess andimprove the flow and heat transfer characteristics of the
Pruess, K.
Multi-stage selection catalytic reduction of NO{sub x} in lean burn engine exhaust
Recent studies suggest that the conversion of NO to NO{sub 2} is an important intermediate step in the selective catalytic reduction (SCR) of NO{sub x} to N{sub 2}. These studies have prompted the development of schemes that use an oxidation catalyst to convert NO to NO{sub 2}, followed by a reduction catalyst to convert NO{sub 2} to N{sub 2}. Multi-stage SCR offers high NO{sub x} reduction efficiency from catalysts that, separately, are not very active for reduction of NO, and alleviates the problem of selectivity between NO reduction and hydrocarbon oxidation. A plasma can also be used to oxidize NO to NO{sub 2}. This paper compares the multi-stage catalytic scheme with the plasma-assisted catalytic scheme for reduction of NO{sub x} in lean-bum engine exhausts. The advantages of plasma oxidation over catalytic oxidation are presented.
Penetrante, B.M.; Hsiao, M.O.; Merritt, B.T.; Vogling, E.
thermal stimulation of an east-flank injection well, the first step in the creation of a heat exchanger at depth. Well datasets from the east flank of the Coso Geothermal Field...
Various analytical, semi-analytical, and empirical models have been proposed to characterize rate and pressure behavior as a function of time in tight/shale gas systems featuring a horizontal well with multiple hydraulic fractures. Despite a small number of analytical models and published numerical studies there is currently little consensus regarding the large-scale flow behavior over time in such systems. The purpose of this work is to construct a fit-for-purpose numerical simulator which will account for a variety of production features pertinent to these systems, and to use this model to study the effects of various parameters on flow behavior. Specific features examined in this work include hydraulically fractured horizontal wells, multiple porosity and permeability fields, desorption, and micro-scale flow effects. The theoretical basis of the model is described in Chapter I, along with a validation of the model. We employ the numerical simulator to examine various tight gas and shale gas systems and to illustrate and define the various flow regimes which progressively occur over time. We visualize the flow regimes using both specialized plots of rate and pressure functions, as well as high-resolution maps of pressure distributions. The results of this study are described in Chapter II. We use pressure maps to illustrate the initial linear flow into the hydraulic fractures in a tight gas system, transitioning to compound formation linear flow, and then into elliptical flow. We show that flow behavior is dominated by the fracture configuration due to the extremely low permeability of shale. We also explore the possible effect of microscale flow effects on gas effective permeability and subsequent gas species fractionation. We examine the interaction of sorptive diffusion and Knudsen diffusion. We show that microscale porous media can result in a compositional shift in produced gas concentration without the presence of adsorbed gas. The development and implementation of the micro-flow model is documented in Chapter III. This work expands our understanding of flow behavior in tight gas and shale gas systems, where such an understanding may ultimately be used to estimate reservoir properties and reserves in these types of reservoirs.
Freeman, Craig M.
Excessive water production (more than 7000 bbl/month per well) from many coalbed methane (CBM) wells in the Powder River Basin of Wyoming is also associated with significant delays in the time it takes for gas production to begin. Analysis of about 550 water-enhancement activities carried out during well completion demonstrates that such activities result in hydraulic fracturing of the coal. Water-enhancement activities, consists of pumping 60 bbl of water/min into the coal seam during approximately 15 min. This is done to clean the well-bore and to enhance CBM production. Hydraulic fracturing is of concern because vertical hydraulic fracture growth could extend into adjacent formations and potentially result in excess CBM water production and inefficient depressurization of coals. Analysis of the pressure-time records of the water-enhancement tests enabled us to determine the magnitude of the least principal stress (S{sub 3}) in the coal seams of 372 wells. These data reveal that because S{sub 3} switches between the minimum horizontal stress and the overburden at different locations, both vertical and horizontal hydraulic fracture growth is inferred to occur in the basin, depending on the exact location and coal layer. Relatively low water production is observed for wells with inferred horizontal fractures, whereas all of the wells associated with excessive water production are characterized by inferred vertical hydraulic fractures. The reason wells with exceptionally high water production show delays in gas production appears to be inefficient depressurization of the coal caused by water production from the formations outside the coal. To minimize CBM water production, we recommend that in areas of known vertical fracture propagation, the injection rate during the water-enhancement tests should be reduced to prevent the propagation of induced fractures into adjacent water-bearing formations.
Colmenares, L.B.; Zoback, M.D. [Stanford University, Stanford, CA (United States). Dept. of Geophysics
In situ stress, fracture, and fluid flow analysis in Well 38C...
and the ambient tectonic stresses that exist within the resource in order to design a hydraulic and thermal stimulation of an east-flank injection well, the first step in the...
Hydraulic Fracturing and Horizontal Gas Well Drilling Reference List Updated June 23, 2011
://www.netl.doe.gov/technologies/oil-gas/publications/EPreports/Shale_Gas_Primer_2009.pdf Good of shale gas drilling in New York State, as well as the most comprehensive collection of data and consultant-supplied analyses Addressing the Environmental Risks from Shale Gas Development (2010) Worldwatch
Self-potential observations during hydraulic fracturing
potential measurements during hydraulic fracturing of BunterMonitoring during hydraulic fracturing using the TG-2 well,fracture processes in hydraulic fracturing, Quarterly Report
Moore, Jeffrey R.; Glaser, Steven D.
located in Northeastern Ohio. The formation is a tight gas sandstone called the Clinton Sand. All was trained with existing data to identify influential parameters in hydraulic fracturing of the Clinton Sand Characteristics The Clinton reservoir is a tight gas sandstone. Natural fracturing is thought to account
Mohaghegh, Shahab
Removal of oxides of nitrogen from gases in multi-stage coal combustion
Polluting NO.sub.x gas values are removed from off-gas of a multi-stage coal combustion process which includes an initial carbonizing reaction, firing of char from this reaction in a fluidized bed reactor, and burning of gases from the carbonizing and fluidized bed reactions in a topping combustor having a first, fuel-rich zone and a second, fuel-lean zone. The improvement by means of which NO.sub.x gases are removed is directed to introducing NO.sub.x -free oxidizing gas such as compressor air into the second, fuel-lean zone and completing combustion with this source of oxidizing gas. Excess air fed to the fluidized bed reactor is also controlled to obtain desired stoichiometry in the first, fuel-rich zone of the topping combustor.
Mollot, Darren J. (Morgantown, WV); Bonk, Donald L. (Louisville, OH); Dowdy, Thomas E. (Orlando, FL)
Removal of oxides of nitrogen from gases in multi-stage coal combustion
Polluting NO{sub x} gas values are removed from off-gas of a multi-stage coal combustion process which includes an initial carbonizing reaction, firing of char from this reaction in a fluidized bed reactor, and burning of gases from the carbonizing and fluidized bed reactions in a topping combustor having a first, fuel-rich zone and a second, fuel-lean zone. The improvement by means of which NO{sub x} gases are removed is directed to introducing NO{sub x}-free oxidizing gas such as compressor air into the second, fuel-lean zone and completing combustion with this source of oxidizing gas. Excess air fed to the fluidized bed reactor is also controlled to obtain desired stoichiometry in the first, fuel-rich zone of the topping combustor. 2 figs.
Mollot, D.J.; Bonk, D.L.; Dowdy, T.E.
Removal of oxides of nitrogen from gases in multi-stage coal combustion
Polluting NO{sub x} gas values are removed from off-gas of a multi-stage coal combustion process which includes an initial carbonizing reaction, firing of char from this reaction in a fluidized bed reactor, and burning of gases from the carbonizing and fluidized bed reactions in a topping combustor having a first, fuel-rich zone and a second, fuel-lean zone. The improvement by means of which NO{sub x} gases are removed is directed to introducing NO{sub x}-free oxidizing gas such as compressor air into the second, fuel-lean zone and completing combustion with this source of oxidizing gas. Excess air fed to the fluidized bed reactor is also controlled to obtain desired stoichiometry in the first, fuel-rich zone of the topping combustor.
Mollot, D.J.; Bonk, D.L.; Dowdy, T.E.
Science Conference Proceedings (OSTI)
Statistical and probabilistic methods for estimating the probability that a fracture is nonconductive (or equivalently, the conductive-fracture frequency) and the distribution of the transmissivities of conductive fractures from transmissivity measurements made in single-hole injection (well) tests were developed. These methods were applied to a database consisting of over 1,000 measurements made in nearly 25 km of borehole at five sites in Sweden. The depths of the measurements ranged from near the surface to over 600-m deep, and packer spacings of 20- and 25-m were used. A probabilistic model that describes the distribution of a series of transmissivity measurements was derived. When the parameters of this model were estimated using maximum likelihood estimators, the resulting estimated distributions generally fit the cumulative histograms of the transmissivity measurements very well. Further, estimates of the mean transmissivity of conductive fractures based on the maximum likelihood estimates of the model's parameters were reasonable, both in magnitude and in trend, with respect to depth. The estimates of the conductive fracture probability were generated in the range of 0.5--5.0 percent, with the higher values at shallow depths and with increasingly smaller values as depth increased. An estimation procedure based on the probabilistic model and the maximum likelihood estimators of its parameters was recommended. Some guidelines regarding the design of injection test programs were drawn from the recommended estimation procedure and the parameter estimates based on the Swedish data. 24 refs., 12 figs., 14 tabs.
Osnes, J.D. (RE/SPEC, Inc., Rapid City, SD (United States)); Winberg, A.; Andersson, J.E.; Larsson, N.A. (Sveriges Geologiska AB, Goeteborg (Sweden))
Science Conference Proceedings (OSTI)
An innovative, multi-stage solar distillation with slope-plate falling film system for seawater desalination is investigated. The system consists of a solar heater (flat plate solar collector) and one evaporation-condensation set that is composed of ... Keywords: solar energy, falling film, desalination
Penghui Gao; Guoqing Zhou; Henglin Lv
Science Conference Proceedings (OSTI)
A standard nominally third-order upwind-biased spatial discretization of the flux-divergence operator was extended to a spherical icosahedral grid. The method can be used with multi-stage time-stepping schemes such as the Runge-Kutta method to ...
Hiroaki Miura
Catalytic multi-stage process for hydroconversion and refining hydrocarbon feeds
A multi-stage catalytic hydrogenation and hydroconversion process for heavy hydrocarbon feed materials such as coal, heavy petroleum fractions, and plastic waste materials. In the process, the feedstock is reacted in a first-stage, back-mixed catalytic reactor with a highly dispersed iron-based catalyst having a powder, gel or liquid form. The reactor effluent is pressure-reduced, vapors and light distillate fractions are removed overhead, and the heavier liquid fraction is fed to a second stage back-mixed catalytic reactor. The first and second stage catalytic reactors are operated at 700-850.degree. F. temperature, 1000-3500 psig hydrogen partial pressure and 20-80 lb./hr per ft.sup.3 reactor space velocity. The vapor and light distillates liquid fractions removed from both the first and second stage reactor effluent streams are combined and passed to an in-line, fixed-bed catalytic hydrotreater for heteroatom removal and for producing high quality naphtha and mid-distillate or a full-range distillate product. The remaining separator bottoms liquid fractions are distilled at successive atmospheric and vacuum pressures, low and intermediate-boiling hydrocarbon liquid products are withdrawn, and heavier distillate fractions are recycled and further upgraded to provide additional low-boiling hydrocarbon liquid products. This catalytic multistage hydrogenation process provides improved flexibility for hydroprocessing the various carbonaceous feedstocks and adjusting to desired product structures and for improved economy of operations.
Comolli, Alfred G. (Yardley, PA); Lee, Lap-Keung (Cranbury, NJ)
Corporation Commission Hydraulic FracturingHydraulic Fracturing
Corporation Commission Hydraulic FracturingHydraulic Fracturing Joint Committee on Energy Commission What is Hydraulic Fracturing d H D It W k?and How Does It Work? · Stimulates a well to increase by Stanolind Oil Company. 2 #12;Kansas Corporation Commission Are Hydraulic Fracture Jobs Performed in Kansas
Peterson, Blake R.
Science Conference Proceedings (OSTI)
Venoco Inc, intends to re-develop the Monterey Formation, a Class III basin reservoir, at South Ellwood Field, Offshore Santa Barbara, California. Well productivity in this field varies significantly. Cumulative Monterey production for individual wells has ranged from 260 STB to 8,700,000 STB. Productivity is primarily affected by how well the well path connects with the local fracture system and the degree of aquifer support. Cumulative oil recovery to date is a small percentage of the original oil in place. To embark upon successful re-development and to optimize reservoir management, Venoco intends to investigate, map and characterize field fracture patterns and the reservoir conduit system. State of the art borehole imaging technologies including FMI, dipole sonic and cross-well seismic, interference tests and production logs will be employed to characterize fractures and micro faults. These data along with the existing database will be used for construction of a novel geologic model of the fracture network. Development of an innovative fracture network reservoir simulator is proposed to monitor and manage the aquifer's role in pressure maintenance and water production. The new fracture simulation model will be used for both planning optimal paths for new wells and improving ultimate recovery. In the second phase of this project, the model will be used for the design of a pilot program for downhole water re-injection into the aquifer simultaneously with oil production. Downhole water separation units attached to electric submersible pumps will be used to minimize surface fluid handling thereby improving recoveries per well and field economics while maintaining aquifer support. In cooperation with the DOE, results of the field studies as well as the new models developed and the fracture database will be shared with other operators. Numerous fields producing from the Monterey and analogous fractured reservoirs both onshore and offshore will benefit from the methodologies developed in this project. This report presents a summary of all technical work conducted during the ninth quarter of Budget Period II.
Steve Horner
Hydraulic fracturing of deep shale beds to develop natural gas has caused concern regarding the potential for various forms of water pollution. Two potential pathways�advective transport through bulk media and preferential flow through fractures�could allow the transport of contaminants from the fractured shale to aquifers. There is substantial geologic evidence that natural vertical flow drives contaminants, mostly brine, to near the surface from deep evaporite sources. Interpretative modeling shows that advective transport could require up to tens of thousands of years to move contaminants to the surface, but also that fracking the shale could reduce that transport time to tens or hundreds of years. Conductive faults or fracture zones, as found throughout the Marcellus shale region, could reduce the travel time further. Injection of up to 15,000,000 L of fluid into the shale generates high pressure at the well, which decreases with distance from the well and with time after injection as the fluid advects through the shale. The advection displaces native fluids, mostly brine, and fractures the bulk media widening existing fractures. Simulated pressure returns to pre-injection levels in about 300 d. The overall system requires from 3 to 6 years to reach a new equilibrium reflecting the significant changes caused by fracking the shale, which could allow advective transport to aquifers in less than 10 years. The rapid expansion of hydraulic fracturing requires that monitoring systems be employed to track the movement of contaminants and that gas wells have a reasonable offset from faults.
Tom Myers
Fracturing of simulated high-level waste glass in canisters
Waste-glass castings generated from engineering-scale developmental processes at the Pacific Northwest Laboratory are generally found to have significant levels of cracks. The causes and extent of fracturing in full-scale canisters of waste glass as a result of cooling and accidental impact are discussed. Although the effects of cracking on waste-form performance in a repository are not well understood, cracks in waste forms can potentially increase leaching surface area. If cracks are minimized or absent in the waste-glass canisters, the potential for radionuclide release from the canister package can be reduced. Additional work on the effects of cracks on leaching of glass is needed. In addition to investigating the extent of fracturing of glass in waste-glass canisters, methods to reduce cracking by controlling cooling conditions were explored. Overall, the study shows that the extent of glass cracking in full-scale, passively-cooled, continuous melting-produced canisters is strongly dependent on the cooling rate. This observation agrees with results of previously reported Pacific Northwest Laboratory experiments on bench-scale annealed canisters. Thus, the cause of cracking is principally bulk thermal stresses. Fracture damage resulting from shearing at the glass/metal interface also contributes to cracking, more so in stainless steel canisters than in carbon steel canisters. This effect can be reduced or eliminated with a graphite coating applied to the inside of the canister. Thermal fracturing can be controlled by using a fixed amount of insulation for filling and cooling of canisters. In order to maintain production rates, a small amount of additional facility space is needed to accomodate slow-cooling canisters. Alternatively, faster cooling can be achieved using the multi-staged approach. Additional development is needed before this approach can be used on full-scale (60-cm) canisters.
Peters, R.D.; Slate, S.C.
This work was conducted to help understand a premature and irregular water breakthrough which resulted from a waterflooding project in the increment II region of Haradh oilfield in Saudi Arabia using different geophysical methods. Oil wells cannot sustain the targeted oil production rates and they die much sooner than expected when water enters the wells. The study attempted to identify fracture systems and their role in the irregular water sweep. Single-well acoustic migration imaging (SWI), walkaround vertical seismic profiling (VSP) and cross-dipole shear wave measurements were used to detect anisotropy caused by fractures near and far from the borehole. The results from all the different methods were analyzed to understand the possible causes of water fingering in the field and determine the reasons for discrepancies and similarities of results of the different methods. The study was done in wells located in the area of the irregular water encroachment in Haradh II oilfield. Waterflooding was performed, where water was injected in the water injector wells drilled at the flanks of Harahd II toward the oil producer wells. Unexpected water coning was noticed in the west flank of the field. While cross-dipole and SWI measurements of a small-scale clearly identify a fracture oriented N60E in the upper tight zone of the reservoir, the VSP measurements of a large-scale showed a dominating fracture system to the NS direction in the upper highpermeability zone of the same reservoir. These results are consistent with the directions of the three main fracture sets in the field at N130E, N80E and N20E, and the direction of the maximum horizontal stress in the field varies between N50E and N90E. Results suggested that the fracture which is detected by cross-dipole at 2 to 4 ft from the borehole is the same fracture detected by SWI 65 ft away from the borehole. This fracture was described using the SWI as being 110 ft from top to bottom, having an orientation of N60E and having an angle of dip of 12� relative to the vertical borehole axis. The detected fracture is located in the tight zone of the reservoir makes a path for water to enter the well from that zone. On the Other hand, the fractures detected by the large-scale VSP measurements in the NS direction are responsible for the high-permeability in the upper zone of the reservoir.
Aljeshi, Hussain Abdulhadi A.
are well de?ned. The history of oil production in AlaskaFurthermore, the history of oil production in Alaska
Lin, C.-Y. Cynthia; Leighty, Wayne
Well drilling apparatus and method
Well drilling rates may be increased by impelling projectiles to fracture rock formations and drilling with rock drill bits through the projectile fractured rock.
Alvis, Robert L. (Albuquerque, NM); Newsom, Melvin M. (Albuquerque, NM)
A two-dimensional finite element model for predicting fracture patterns obtained in high energy gas fracture experiments is presented. In these experiments, a mixture of propellants is used instead of explosives to fracture the rock surrounding the borehole. The propellant mixture is chosen to tailor the pressure pulse so that multiple fractures emanate from the borehole. The model allows the fracture pattern and pressure pulse to be calculated for different combinations of propellant mixture, in situ stress conditions, and rock properties. The model calculates the amount of gas generated by the burning propellants using a burn rate given by a power law in pressure. By assuming that the gas behaves as a perfect gas and that the flow down the fractures is isothermal, the loss of gas from the borehole due to flow down the cracks is accounted for. The flow of gas down the cracks is included in an approximate manner by assuming self-similar pressure profiles along the fractures. Numerical examples are presented and compared to three different full-scale experiments. Results show a good correlation with the experimental data over a wide variety of test parameters. 9 reference, 10 figures, 3 tables.
Taylor, L.M.; Swenson, D.V.; Cooper, P.W.
Low-permeability gas wells often produce less than predicted after a fracture treatment. One of the reasons for this is that fracture lengths calculated after stimulation are often less than designed lengths. While actual fracture lengths may be shorter due to fracture growth out of zone, improper proppant settling, or proppant flowback, short calculated fracture lengths can also result from incorrect analysis techniques. It is known that fracturing fluid that remains in the fracture and formation after a hydraulic fracture treatment can decrease the productivity of a gas well by reducing the relative permeability to gas in the region invaded by this fluid. However, the relationships between fracture fluid cleanup, effective fracture length, and well productivity are not fully understood. In this work I used reservoir simulation to determine the relationship between fracture conductivity, fracture fluid production, effective fracture length, and well productivity. I simulated water saturation and pressure profiles around a propped fracture, tracked gas production along the length of the propped fracture, and quantified the effective fracture length (i.e., the fracture length under single-phase flow conditions that gives similar performance as for multiphase flow conditions), the "cleanup" fracture length (i.e., the fracture length corresponding to 90% cumulative gas flow rate into the fracture), and the "apparent" fracture length (i.e., the fracture length where the ratio of multiphase to single-phase gas entry rate profiles is unity). This study shows that the proppant pack is generally cleaned up and the cleanup lengths are close to designed lengths in relatively short times. Although gas is entering along entire fracture, fracturing fluid remains in the formation near the fracture. The water saturation distribution affects the gas entry rate profile, which determines the effective fracture length. Subtle changes in the gas rate entry profile can result in significant changes in effective fracture length. The results I derived from this work are consistent with prior work, namely that greater fracture conductivity results in more effective well cleanup and longer effective fracture lengths versus time. This study provides better explanation of mechanisms that affect fracturing fluid cleanup, effective fracture length, and well productivity than previous work.
Lolon, Elyezer P.
Science Conference Proceedings (OSTI)
Many studies have demonstrated that back-propagation neural network can be effectively used to uncover the nonlinearity in the financial markets. Unfortunately, back-propagation algorithm suffers the problems of slow convergence, inefficiency, and lack ... Keywords: Artificial neural network, Back-propagation, Food price forecasting, Multi-stage optimization approach, Time series forecasting
Zou Haofei; Xia Guoping; Yang Fangting; Yang Han
Venoco Inc, intends to re-develop the Monterey Formation, a Class III basin reservoir, at South Ellwood Field, Offshore Santa Barbara, California. Well productivity in this field varies significantly. Cumulative Monterey production for individual wells has ranged from 260 STB to 8,700,000 STB. Productivity is primarily affected by how well the well path connects with the local fracture system and the degree of aquifer support. Cumulative oil recovery to date is a small percentage of the original oil in place. To embark upon successful re-development and to optimize reservoir management, Venoco intends to investigate, map and characterize field fracture patterns and the reservoir conduit system. State of the art borehole imaging technologies including FMI, dipole sonic and cross-well seismic, interference tests and production logs will be employed to characterize fractures and micro faults. These data along with the existing database will be used for construction of a novel geologic model of the fracture network. Development of an innovative fracture network reservoir simulator is proposed to monitor and manage the aquifer's role in pressure maintenance and water production. The new fracture simulation model will be used for both planning optimal paths for new wells and improving ultimate recovery. In the second phase of this project, the model will be used for the design of a pilot program for downhole water re-injection into the aquifer simultaneously with oil production. Downhole water separation units attached to electric submersible pumps will be used to minimize surface fluid handling thereby improving recoveries per well and field economics while maintaining aquifer support. In cooperation with the DOE, results of the field studies as well as the new models developed and the fracture database will be shared with other operators. Numerous fields producing from the Monterey and analogous fractured reservoirs both onshore and offshore will benefit from the methodologies developed in this project. This report presents a summary of all technical work conducted during the fifth quarter of Budget Period II.
Steve Horner
Fracturing fluids -- then and now
Science Conference Proceedings (OSTI)
Fracturing fluid provides the means by which the hydraulic fracturing process can take place. All applications of well stimulation by fracturing must include selection of fracturing fluid in the initial phases of fracture design and treatment planning. Fracturing fluid has two important purposes: (1) to provide sufficient viscosity to suspend and transport proppant deep into the created fracture system and (2) to decompose, or break, chemically to a low viscosity to allow flowback of a major part of the fluid to the surface for fracture cleanup after the treatment is completed. Because of the importance of its rheological properties and behavior in the fracture under reservoir conditions during (and immediately after) the treatment, service company research laboratories have spent millions of dollars on R and D of fracturing fluids.
Jennings, A.R. Jr. [Enhanced Well Stimulation Inc., Plano, TX (United States)
Science Conference Proceedings (OSTI)
Non-enzymatic glycation of tissue proteins has important implications in the development of complications of diabetes mellitus. While electron transfer dissociation (ETD) has been shown to outperform collision-induced dissociation (CID) in sequencing glycated peptides by tandem mass spectrometry, ETD instrumentation is not yet available in all laboratories. In this study, we evaluated different advanced CID techniques (i.e., neutral-loss triggered MS3 and multi-stage activation) during LC-MSn analyses of Amadori-modified peptides enriched from human serum glycated in vitro. During neutral-loss triggered MS3 experiments, MS3 scans triggered by neutral-losses of 3 H2O or 3 H2O + HCHO produced similar results in terms of glycated peptide identifications. However, neutral losses of 3 H2O resulted in significantly more glycated peptide identifications during multi-stage activation experiments. Overall, the multi-stage activation approach produced more glycated peptide identifications, while the neutral-loss triggered MS3 approach resulted in much higher specificity. Both techniques offer a viable alternative to ETD for identifying glycated peptides when that method is unavailable.
Zhang, Qibin; Petyuk, Vladislav A.; Schepmoes, Athena A.; Orton, Daniel J.; Monroe, Matthew E.; Yang, Feng; Smith, Richard D.; Metz, Thomas O.
NLE Websites -- All DOE Office Websites (Extended Search)
HYDRAULIC FRACTURING In addition to the recovery processes featured in this series of drawings, hydraulic fracturing is included as an example of technologies that contribute to...
per well over all wells(oil wells, gas wells, dry holes), ina higher oil price decreases pro?ts as well. For preliminaryof wells that were drilled; and monthly production of oil,
Lin, C.-Y. Cynthia
Investigation of Created Fracture Geometry through Hydraulic Fracture Treatment Analysis
Successful development of shale gas reservoirs is highly dependent on hydraulic fracture treatments. Many questions remain in regards to the geometry of the created fractures. Production data analysis from some shale gas wells quantifies a much smaller stimulated pore volume than what would be expected from microseismic evidence and reports of fracturing fluids reaching distant wells. In addition, claims that hydraulic fracturing may open or reopen a network of natural fractures is of particular interest. This study examines hydraulic fracturing of shale gas formations with specific interest in fracture geometry. Several field cases are analyzed using microseismic analysis as well as net pressure analysis of the fracture treatment. Fracture half lengths implied by microseismic events for some of the stages are several thousand feet in length. The resulting dimensions from microseismic analysis are used for calibration of the treatment model. The fracture profile showing created and propped fracture geometry illustrates that it is not possible to reach the full fracture geometry implied by microseismic given the finite amount of fluid and proppant that was pumped. The model does show however that the created geometry appears to be much larger than half the well spacing. From a productivity standpoint, the fracture will not drain a volume more than that contained in half of the well spacing. This suggests that for the case of closely spaced wells, the treatment size should be reduced to a maximum of half the well spacing. This study will provide a framework for understanding hydraulic fracture treatments in shale formations. In addition, the results from this study can be used to optimize hydraulic fracture treatment design. Excessively large treatments may represent a less than optimal approach for developing these resources.
Ahmed, Ibraheem 1987-
Fracture characterization of multilayered reservoirs
Science Conference Proceedings (OSTI)
Fracture treatment optimization techniques have been developed using Long-Spaced-Digital-Sonic (LSDS) log, pumpin-flowback, mini-frac, and downhole treating pressure data. These analysis techniques have been successfully applied in massive hydraulic fracturing (MHF) of ''tight gas'' wells. Massive hydraulic fracture stimulations have been used to make many tight gas reservoirs commercially attractive. However, studies have shown that short highly conductive fractures are optimum for the successful stimulation of wells in moderate permeability reservoirs. As a result, the ability to design and place optimal fractures in these reservoirs is critical. This paper illustrates the application of fracture analysis techniques to a moderate permeability multi-layered reservoir. These techniques were used to identify large zonal variations in rock properties and pore pressure which result from the complex geology. The inclusion of geologic factors in fracture treatment design allowed the placement of short highly conductive fractures which were used to improve injectivity and vertical sweep, and therefore, ultimate recovery.
Britt, L.K.; Larsen, M.J.
Lisburne Formation fracture characterization and flow modeling
Evaluation of fractured reservoirs for fluid flow and optimal well placement is often very complicated. In general, fractures enhance permeability and increase access to matrix surface, but their random aspects create difficulties for analysis and performance prediction. Each reservoir has unique aspects which require individual assessment. This study examined fracture properties in a part of the Carboniferous Lisburne Formation. Field study of outcrops yielded information on two sets of large-scale fractures (NNW and ENE orientations) from the lower Wahoo Limestone in the eastern Sadlerochit Mountains. Several statistical methods were used on these data to find appropriate models describing the megafracture properties. For NNW fracture height and ENE fracture spacing, the gamma model appears to adequately describe the distribution. NNW fracture spacing and ENE fracture height are lognormally distributed. Results of the statistical analyses were used as input for fracture set generation and modeling using "FracMan". Modeling different borehole orientations in the fractured domain revealed that horizontal wells with 60? azimuth have an optimal trajectory, resulting in the maximum number and area of fracture connections. The orientation maximizing the number of fracture connections did not necessarily give the maximum area. Conductivity analysis showed that the fracture network is weakly anisotropic and above the percolation threshold. The fracture conductance is strongly dependent on the NNW fracture set; larger fractures influence fluid flow more than smaller fractures. Fracture strike and dip variability increased the system interconnectivity, but did not affect the optimal wellbore orientation. Incorporating ENE fracture termination against the NNW fractures decreased the system conductance and shifted the optimal wellbore trajectory towards the direction perpendicular to the NNW set. Reservoir engineering implications of this study include: guidelines for optimal wellbore orientations, the relative placement of injectors and producers along the bisectors between the two fracture sets, and the importance of including fracture terminations. Further work should investigate the influence of variations in fracture aperture and transmissivities, and drainage area, and extend the analysis to additional units of the Lisburne Group.
Karpov, Alexandre Valerievich
Suspensions in hydraulic fracturing
Science Conference Proceedings (OSTI)
Suspensions or slurries are widely used in well stimulation and hydraulic fracturing processes to enhance the production of oil and gas from the underground hydrocarbon-bearing formation. The success of these processes depends significantly upon having a thorough understanding of the behavior of suspensions used. Therefore, the characterization of suspensions under realistic conditions, for their rheological and hydraulic properties, is very important. This chapter deals with the state-of-the-art hydraulic fracturing suspension technology. Specifically it deals with various types of suspensions used in well stimulation and fracturing processes, their rheological characterization and hydraulic properties, behavior of suspensions in horizontal wells, review of proppant settling velocity and proppant transport in the fracture, and presently available measurement techniques for suspensions and their merits. Future industry needs for better understanding of the complex behavior of suspensions are also addressed. 74 refs., 21 figs., 1 tab.
Shah, S.N. [Univ. of Oklahoma, Norman, OK (United States)
Method for enhancement of sequential hydraulic fracturing using control pulse fracturing
Science Conference Proceedings (OSTI)
A method is described for creating multiple sequential hydraulic fractures via hydraulic fracturing combined with controlled pulse fracturing where two wells are utilized comprising: (a) drilling and completing a first and second well so that the wells will be in fluid communication with each other after subsequent fracturing in each well; (b) creating more than two simultaneous multiple vertical fractures via a controlled pulse fracturing method in the second well; (c) thereafter hydraulically fracturing the reservoir via the first well thereby creating fractures in the reservoir and afterwards shutting-in the first well without any induced pressure; (d) applying thereafter hydraulic pressure to the reservoir via the second well in an amount sufficient to fracture the reservoir thereby forming a first hydraulic fracture perpendicular to the least principal in-situ stress; (e) maintaining the hydraulic pressure on the reservoir while pumping via the second well alternate slugs of a thin-fluid spacer and a temporary blocking agent having a proppant therein whereupon a second hydraulic fracture is initiated; (f) maintaining the hydraulic pressure on the second well while pumping alternate slugs of spacer and blocking agent into the second hydraulic fracture thereby causing the second hydraulic fracture to propagate away from the first hydraulic fracture in step (e) in a curved trajectory which intersects a fracture created in the first well; (g) maintaining the hydraulic pressure while pumping as in step (f) whereupon another hydraulic fracture initiates causing another curved fracture trajectory to form and intersect the fracture created in the first well; and (h) repeated steps (f) and (g) until a desired number of hydraulic fractures are created which allows a substantial improvement in removing a natural resource from the reservoir.
Jennings, A.R. Jr.; Strubhar, M.K.
Hydraulic fracturing technology has been successfully applied for well stimulation of low and high permeability reservoirs for numerous years. Treatment optimization and improved economics have always been the key to the success and it is more so when the reservoirs under consideration are marginal. Fluids are widely used for the stimulation of wells. The Fracturing Fluid Characterization Facility (FFCF) has been established to provide the accurate prediction of the behavior of complex fracturing fluids under downhole conditions. The primary focus of the facility is to provide valuable insight into the various mechanisms that govern the flow of fracturing fluids and slurries through hydraulically created fractures. During the time between September 30, 1992, and March 31, 2000, the research efforts were devoted to the areas of fluid rheology, proppant transport, proppant flowback, dynamic fluid loss, perforation pressure losses, and frictional pressure losses. In this regard, a unique above-the-ground fracture simulator was designed and constructed at the FFCF, labeled ''The High Pressure Simulator'' (HPS). The FFCF is now available to industry for characterizing and understanding the behavior of complex fluid systems. To better reflect and encompass the broad spectrum of the petroleum industry, the FFCF now operates under a new name of ''The Well Construction Technology Center'' (WCTC). This report documents the summary of the activities performed during 1992-2000 at the FFCF.
Subhash Shah
Raft River well stimulation experiments: geothermal reservoir well stimulation program
The Geothermal Reservoir Well Stimulation Program (GRWSP) performed two field experiments at the Raft River KGRA in 1979. Wells RRGP-4 and RRGP-5 were selected for the hydraulic fracture stimulation treatments. The well selection process, fracture treatment design, field execution, stimulation results, and pre- and post-job evaluations are presented.
Not Available
Hydraulic Fracturing (Vermont)
Energy.gov (U.S. Department of Energy (DOE))
Vermont prohibits hydraulic fracturing or the collection, storage, or treatment of wastewater from hydraulic fracturing
A Simulator for Design & Management of Injection Well
or Hydraulically Fractured Wells Waterflooding and Surface Facilities Design · Performance Prediction of Vertical
Texas at Austin, University of
Computational fluid dynamics or CFD isan importanttool thatis used at various stages in the design of highly complex turbomachinery such as compressorand turbine stages that are used in land and air based power generation units. The ability of CFD to predict the performance characteristics of a specific blade design is challenged by the need to use various turbulence models to simulate turbulent flows as well as transition models to simulate laminar to turbulent transition that can be observed in various turbomachinery designs. Moreover, CFD is based on numerically solving highly complex differential equations, which through the use of a grid to discretize the geometry introduces numerical errors. Allthese factors combine to challenge CFD�s role as a predictor of blade performance. It has been generallyfound that CFD in its current state of the art is best used to compare between various design points and not as a pure predictor of performances. In this study the capability of CFD, and turbulence modeling, in turbomachinery based geometry is assessed.Three different blade designs are tested, that include an advanced two-stage turbine blade design, a three stage 2D or cylindrical design and finally a three stage bowed stator and rotor design. Allcases were experimentally tested at the Texas A&Muniversity Turbomachinery Performance and Flow Research Laboratory (TPFL).In all cases CFD provided good insights into fundamental turbomachinery flow physics, showing the expected improvement from using 2D cylindrical blades to 3D bowed blade designs in abating the secondary flow effects which are dominant loss generators.However, comparing experimentally measured performance results to numerically predicted shows a clear deficiency, where the CFD overpredicts performance when compared to experimentallyobtained data, largely underestimating the various loss mechanisms. In a relative sense, CFD as a tool allows the user to calculate the impact a new feature or change can have on a baseline design. CFD will also provide insight into what are the dominant physics that explain why a change can provide an increase or decrease in performance. Additionally,as part of this study, one of the main factors that affect the performance of modern turbomachinery is transition from laminar to turbulent flow.Transition is an influential phenomena especially in high pressure turbines, and is sensitive to factors such asupstream incidentwake frequency and turbulence intensity.A model experimentally developed, is implemented into a CFD solver and compared to various test results showing greater capability in modeling the effects of reduced frequency on the transition point and transitional flow physics. This model is compared to industry standard models showing favorable prediction performance due to its abilityto account for upstream wake effects which most current model are unable to account for.
Abdelfattah, Sherif Alykadry
A cleaning plant positioned within an annular fluidized bed combustion chamber is divided into a plurality of separate cleaning stages, wherein a first stage is located adjacent the fluidized bed and additional stages are arranged within the first stage. Each stage comprises a plurality of separate cleaning devices which act in parallel, while cleaning devices of different stages act in series to remove debris from the combustion gases that exit from the fluidized bed combustion chamber.
Kullendorff, A.; Wikner, J.
Science Conference Proceedings (OSTI)
This book contains papers on hydraulic fracturing. Topics covered include: An overview of recent advances in hydraulic fracturing technology; Containment of massive hydraulic fracture; and Fracturing with a high-strength proppant.
Not Available
Apparatus and method for monitoring underground fracturing
An apparatus and method for measuring deformation of a rock mass around the vicinity of a fracture, commonly induced by hydraulic fracturing is provided. To this end, a well is drilled offset from the proposed fracture region, if no existing well is present. Once the well is formed to a depth approximately equal or exceeding the depth of the proposed fracture, a plurality of inclinometers, for example tiltmeters, are inserted downhole in the well. The inclinometers are located both above and below the approximate depth of the proposed fracture. The plurality of inclinometers may be arranged on a wireline that may be retrieved from the downhole portion of the well and used again or, alternatively, the inclinometers may be cemented in place. In either event, the inclinometers are used to measure the deformation of the rock around the induced fracture. 13 figs.
Warpinski, N.R.; Steinfort, T.D.; Branagan, P.T.; Wilmer, R.H.
Apparatus and method for monitoring underground fracturing
An apparatus and method for measuring deformation of a rock mass around the vicinity of a fracture, commonly induced by hydraulic fracturing is provided. To this end, a well is drilled offset from the proposed fracture region, if no existing well is present. Once the well is formed to a depth approximately equal or exceeding the depth of the proposed fracture, a plurality of inclinometers, for example tiltmeters, are inserted downhole in the well. The inclinometers are located both above and below the approximate depth of the proposed fracture. The plurality of inclinometers may be arranged on a wireline that may be retrieved from the downhole portion of the well and used again or, alternatively, the inclinometers may be cemented in place. In either event, the inclinometers are used to measure the deformation of the rock around the induced fracture.
Warpinski, Norman R. (Albuquerque, NM); Steinfort, Terry D. (Tijeras, NM); Branagan, Paul T. (Las Vegas, NV); Wilmer, Roy H. (Las Vegas, NV)
??Hydraulic fracturing has been used in most oil and gas wells to increase production by creating fractures that extend from the wellbore into the formation.� (more)
Kim, Gun Ho
Using seismic tomography to characterize fracture systems induced by hydraulic fracturing
Microearthquakes induced by hydraulic fracturing have been studied by many investigators to characterize fracture systems created by the fracturing process and to better understand the locations of energy resources in the earth`s subsurface. The pattern of the locations often contains a great deal of information about the fracture system stimulated during the hydraulic fracturing. Seismic tomography has found applications in many areas for characterizing the subsurface of the earth. It is well known that fractures in rock influence both the P and S velocities of the rock. The influence of the fractures is a function of the geometry of the fractures, the apertures and number of fractures, and the presence of fluids in the fractures. In addition, the temporal evolution of the created fracture system can be inferred from the temporal changes in seismic velocity and the pattern of microearthquake locations. Seismic tomography has been used to infer the spatial location of a fracture system in a reservoir that was created by hydraulic fracturing.
Fehler, M.; Rutledge, J.
Permeability enhancement using high energy gas fracturing
This paper reports the results of a preliminary study of using High Energy Gas Fracturing (HEGF) techniques for geothermal well stimulation. Experiments conducted in the G-tunnel complex at the Nevada Test Site (NTS) showed that multiple fractures could be created in water-filled boreholes using HEGF. Therefore, the method is potentially useful for geothermal well stimulation. 4 refs., 11 figs.
Chu, T.Y.; Cuderman, J.F.; Jung, J.; Jacobson, R.D.
Fracture characterization study
First, the origin, nature, and significance of fractures in general are discussed. Next, discussions are directed toward the designation and classification of fractures. Some typical fracture measurement techniques are discussed. Finally, geothermal fracture systems are investigated and correlations made to determine which fracture technologies from oil field work are applicable to geothermal systems. (MHR)
Kehrman, R.F.
Hydrodynamics of a vertical hydraulic fracture
We have developed a numerical algorithm, HUBBERT, to simulate the hydrodynamics of a propagating vertical, rectangular fracture in an elastic porous medium. Based on the IFD method, this algorithm assumes fracture geometry to be prescribed. The breakdown and the creation of the incipient fracture is carried out according to the Hubbert-Willis theory. The propagation of the fracture is based on the criterion provided by Griffith, based on energy considerations. The deformation properties of the open fracture are based on simple elasticity solutions. The fracture is assumed to have an elliptical shape to a distance equal to the fracture height, beyond which the shape is assumed to be parallel plate. A consequence of Griffith's criterion is that the fracture must propagate in discrete steps. The parametric studies carried out suggest that for a clear understanding of the hydrodynamics of the hydraulic fracture many hitherto unrecognized parameters must be better understood. Among these parameters one might mention, efficiency, aperture of the newly formed fracture, stiffness of the newly formed fracture, relation between fracture aperture and permeability, and well bore compliance. The results of the studies indicate that the patterns of pressure transients and the magnitudes of fracture length appear to conform to field observations. In particular, the discrete nature of fracture propagation as well as the relevant time scales of interest inferred from the present work seem to be corroborated by seismic monitoring in the field. The results suggest that the estimation of least principal stress can be reliably made either with shut in data or with reinjection data provided that injection rates are very small.
Narasimhan, T.N.
Identifying Fracture Types and Relative Ages Using Fluid Inclusion Stratigraphy
Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Understanding the life cycle of a fracture in a geothermal system is fundamental to the development of techniques for creating fractures. Recognizing the stage of a fracture, whether it is currently open and transmitting fluids; if it recently has closed; or if it is an ancient fracture would assist in targeting areas for further fracture stimulation. Identifying dense fracture areas as well as large open fractures from small fracture systems will also assist in fracture stimulation selection. Geothermal systems are constantly generating fractures, and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. Fluid inclusions trapped in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. Our hypothesis is that fractures over their life cycle have different chemical signatures that we can see in fluid inclusion gas analysis and by using the new method of fluid inclusion stratigraphy (FIS) the different stages of fractures, along with an estimate of fracture size can be identified during the well drilling process. We have shown with this study that it is possible to identify fracture locations using FIS and that different fractures have different chemical signatures however that signature is somewhat dependent upon rock type. Open, active fractures correlate with increase concentrations of CO2, N2, Ar, and to a lesser extent H2O. These fractures would be targets for further enhancement. The usefulness of this method is that it is low cost alternative to current well logging techniques and can be done as a well is being drilled.
Dilley, Lorie M.; Norman, David; Owens, Lara
Method of fracturing a geological formation
An improved method of fracturing a geological formation surrounding a well bore is disclosed. A relatively small explosive charge is emplaced in a well bore and the bore is subsequently hydraulically pressurized to a pressure less than the formation breakdown pressure and preferably greater than the fracture propagation pressure of the formation. The charge is denoted while the bore is so pressurized, resulting in the formation of multiple fractures in the surrounding formation with little or no accompanying formation damage. Subsequent hydraulic pressurization can be used to propagate and extend the fractures in a conventional manner. The method is useful for stimulating production of oil, gas and possibly water from suitable geologic formations.
Johnson, James O. (2679-B Walnut, Los Alamos, NM 87544)
Science Conference Proceedings (OSTI)
Numerical simulation of water injection in discrete fractured media with capillary pressure is a challenge. Dual-porosity models in view of their strength and simplicity can be mainly used for sugar-cube representation of fractured media. In such a representation, the transfer function between the fracture and the matrix block can be readily calculated for water-wet media. For a mixed-wet system, the evaluation of the transfer function becomes complicated due to the effect of gravity. In this work, they use a discrete-fracture model in which the fractures are discretized as one dimensional entities to account for fracture thickness by an integral form of the flow equations. This simple step greatly improves the numerical solution. Then the discrete-fracture model is implemented using a Galerkin finite element method. The robustness and the accuracy of the approach are shown through several examples. First they consider a single fracture in a rock matrix and compare the results of the discrete-fracture model with a single-porosity model. Then, they use the discrete-fracture model in more complex configurations. Numerical simulations are carried out in water-wet media as well as in mixed-wet media to study the effect of matrix and fracture capillary pressures.
Abbas Firoozabadi
Injection into a fractured geothermal reservoir
A detailed study is made on the movement of the thermal fronts in the fracture and in the porous medium when 100{sup 0}C water is injected into a 300{sup 0}C geothermal reservoir with equally spaced horizontal fractures. Numerical modeling calculations were made for a number of thermal conductivity values, as well as different values of the ratio of fracture and rock medium permeabilities. One important result is an indication that although initially, the thermal front in the fracture moves very fast relative to the front in the porous medium as commonly expected, its speed rapidly decreases. At some distance from the injection well the thermal fronts in the fracture and the porous medium coincide, and from that point they advance together. The implication of this result on the effects of fractures on reinjection into geothermal reservoirs is discussed.
Bodvarsson, G.S.; Tsang, C.F.
Linear Elastic Fracture Mechanics
Science Conference Proceedings (OSTI)
..., ASM International, 1996, p 371�??380ASM Handbook, Vol 19, Fatigue And FractureS.D. Antolovich and B.F. Antolovich, An Introduction to Fracture
Unconventional gas has become an important resource to help meet our future energy demands. Although plentiful, it is difficult to produce this resource, when locked in a massive sedimentary formation. Among all unconventional gas resources, tight gas sands represent a big fraction and are often characterized by very low porosity and permeability associated with their producing formations, resulting in extremely low production rate. The low flow properties and the recovery factors of these sands make necessary continuous efforts to reduce costs and improve efficiency in all aspects of drilling, completion and production techniques. Many of the recent improvements have been in well completions and hydraulic fracturing. Thus, the main goal of a hydraulic fracture is to create a long, highly conductive fracture to facilitate the gas flow from the reservoir to the wellbore to obtain commercial production rates. Fracture conductivity depends on several factors, such as like the damage created by the gel during the treatment and the gel clean-up after the treatment. This research is focused on predicting more accurately the fracture conductivity, the gel damage created in fractures, and the fracture cleanup after a hydraulic fracture treatment under certain pressure and temperature conditions. Parameters that alter fracture conductivity, such as polymer concentration, breaker concentration and gas flow rate, are also examined in this study. A series of experiments, using a procedure of �dynamical fracture conductivity test�, were carried out. This procedure simulates the proppant/frac fluid slurries flow into the fractures in a low-permeability rock, as it occurs in the field, using different combinations of polymer and breaker concentrations under reservoirs conditions. The result of this study provides the basis to optimize the fracturing fluids and the polymer loading at different reservoir conditions, which may result in a clean and conductive fracture. Success in improving this process will help to decrease capital expenditures and increase the production in unconventional tight gas reservoirs.
Correa Castro, Juan
Interactive fracture design model
A computer program is described that can be used to design a fracture stimulation treatment for a geothermal reservoir. The program uses state-of-the-art methods to calculate the temperature of the fracture fluid as a function of time and distance in the fracture. This information is used to determine the temperature dependent properties of the fracture fluid. These fluid properties are utilized to calculate the fracture geometry as a function of time. The fracture geometry and temperature distribution of the fracture fluid are coupled so the subroutines that calculate these distributions have been made interactive.
Not Available
Hydraulic Fracturing | Open Energy Information
Hydraulic Fracturing Hydraulic Fracturing Jump to: navigation, search More info on OpenEI Oil and Gas Gateway Federal Environmental Statues Federal Oil and Gas Statutes Oil and Gas Companies United States Oil and Gas Boards International Oil and Gas Boards Other Information Fracking Regulations by State Wells by State Fracking Chemicals Groundwater Protection Related Reports A Perspective on Health and Natural Gas Operations: A Report for Denton City Council Just the Fracking Facts The Politics of 'Fracking': Regulating Natural Gas Drilling Practices in Colorado and Texas Addressing the Environmental Risks from Shale Gas Development Water Management Technologies Used by Marcellus Shale Gas Producers Methane contamination of drinking wateraccompanying gas-well drilling and hydraulic fracturing
Fracture Modeling and Flow Behavior in Shale Gas Reservoirs Using Discrete Fracture Networks
Fluid flow process in fractured reservoirs is controlled primarily by the connectivity of fractures. The presence of fractures in these reservoirs significantly affects the mechanism of fluid flow. They have led to problems in the reservoir which results in early water breakthroughs, reduced tertiary recovery efficiency due to channeling of injected gas or fluids, dynamic calculations of recoverable hydrocarbons that are much less than static mass balance ones due to reservoir compartmentalization, and dramatic production changes due to changes in reservoir pressure as fractures close down as conduits. These often lead to reduced ultimate recoveries or higher production costs. Generally, modeling flow behavior and mass transport in fractured porous media is done using the dual-continuum concept in which fracture and matrix are modeled as two separate kinds of continua occupying the same control volume (element) in space. This type of numerical model cannot reproduce many commonly observed types of fractured reservoir behavior since they do not explicitly model the geometry of discrete fractures, solution features, and bedding that control flow pathway geometry. This inaccurate model of discrete feature connectivity results in inaccurate flow predictions in areas of the reservoir where there is not good well control. Discrete Fracture Networks (DFN) model has been developed to aid is solving some of these problems experienced by using the dual continuum models. The Discrete Fracture Networks (DFN) approach involves analysis and modeling which explicitly incorporates the geometry and properties of discrete features as a central component controlling flow and transport. DFN are stochastic models of fracture architecture that incorporate statistical scaling rules derived from analysis of fracture length, height, spacing, orientation, and aperture. This study is focused on developing a methodology for application of DFN to a shale gas reservoir and the practical application of DFN simulator (FracGen and NFflow) for fracture modeling of a shale gas reservoir and also studies the interaction of the different fracture properties on reservoir response. The most important results of the study are that a uniform fracture network distribution and fracture aperture produces the highest cumulative gas production for the different fracture networks and fracture/well properties considered.
Ogbechie, Joachim Nwabunwanne
Fracture detection and mapping
Because the costs of drilling, completing, and testing a well can be extremely high, it is important to develop better tools and methods for locating high permeability zones prior to drilling, and to develop better tools and methods for identifying and characterizing major fracture zones during the drilling and well testing stages. At the recommendation of the LBL Industry Review Panel on Geothermal Reservoir Technology, we organized and convened a one-day workshop this past July to discuss various aspects of DOE's current and planned activities in fracture detection, to review the geothermal industry's near-term and long-term research needs, to determine the priority of those needs, to disseminate to industry the status of research in progress, and to discuss the possibility of future joint research between industry and DOE. In this paper we present a brief overview of the workshop from the perspective of those who participated in it and provided us with written comments to a questionnaire that was distributed.
Goldstein, N.E.; Iovenitti, J.L.
Studies of injection into naturally fractured reservoirs
A semi-analytical model for studies of cold water injection into naturally fractured reservoirs has been developed. The model can be used to design the flow rates and location of injection wells in such systems. The results obtained using the model show that initially the cold water will move very rapidly through the fracture system away from the well. Later on, conductive heat transfer from the rock matrix blocks will retard the advancement of the cold water front, and eventually uniform energy sweep conditions will prevail. Where uniform energy sweep conditions are reached the cold waer movement away from the injection well will be identical to that in a porous medium; consequently maximum energy recovery from the rock matrix will be attained. The time of uniform energy sweep and the radial distance from the injection well where it occurs are greatly dependent upon the fracture spacing, but independent of the fracture aperture.
Boedvarsson, G.S.; Lai, C.H.
Anomalous fracture-extension pressure in granitic rocks
Fracture-extension pressures appreciably higher than the least principal earth-stress were observed in hydraulic fractures formed in a pair of 3 km (9600 ft) deep boreholes drilled near the Valles Caldera in northern New Mexico. Pressurization of open wellbores in rock containing preexisting fractures may open these fractures, instead of creating new fractures at right angles to the least principal stress. The pressure necessary to flow into these fractures may be appreciably higher than the least principal stress. Upon sand-propping one such pre-existing fracture, a lower fracture extension pressure was observed. A second fracture in a parallel well-bore 92 m (300 ft) away, at the same depth of 2 km (6500 ft) exhibited the lower fracture extension pressure without propping, but with about 90/sup 0/ difference in fracture direction. Fractures created through perforations at a depth of 3 km (9600 ft) not only exhibited breakdown pressures upon initial pressurization, but sometimes even higher ''breakdown'' pressures upon repressurization. These phenomena may be of interest in the interpretation of earth stress measurements made by hydraulic fracturing.
Aamodt, R.L.; Potter, R.M.
An in-depth understanding of dynamic ductile fracture is one of the most important steps to improve the survivability of critical structures such as the lost Twin Towers. In the present thesis, the macroscopic fracture ...
Teng, Xiaoqing
Fracture Permeability and In Situ Stress in the Dixie Valley...
Reservoir Abstract Borehole televiewer, temperature and flowmeter logs and hydraulic fracturing stress measurements conducted in six wells penetrating a geothermal reservoir...
High-permeability fracturing: The evolution of a technology
Since its introduction almost 50 years ago, hydraulic fracturing has been the prime engineering tool for improving well productivity either by bypassing near-wellbore damage or by actually stimulating performance. Historically (and in many instances erroneously), the emphasis for propped fracturing was on fracture length, culminating in massive treatments for tight-gas sands with several million pounds of proppant and design lengths in excess of 1,500 ft. More recently, the importance of fracture conductivity has become appreciated. This paper uses field examples to trace the history, development, and application of TSO fracturing to high-permeability formations, including fracturing to increase PI, as well as applications aimed at improving completions in unconsolidated sands. Potential applications of fracturing to bypass the need for sand control are explored. Finally, the use of fracturing as a reservoir-management tool is examined through use of a propped fracture to alter the vertical flow profile of a well to maximize reserves. This particular use of fracturing leads to cases where careful design of both fracture length and conductivity is required; i.e., too much conductivity is as damaging to reservoir management as too little.
Smith, M.B.; Hannah, R.R.
Microseismicity, stress, and fracture in the Coso geothermal field,
Microseismicity, stress, and fracture in the Coso geothermal field, Microseismicity, stress, and fracture in the Coso geothermal field, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Microseismicity, stress, and fracture in the Coso geothermal field, California Details Activities (1) Areas (1) Regions (0) Abstract: Microseismicity, stress, and fracture in the Coso geothermal field are investigated using seismicity, focal mechanisms and stress analysis. Comparison of hypocenters of microearthquakes with locations of development wells indicates that microseismic activity has increased since the commencement of fluid injection and circulation. Microearthquakes in the geothermal field are proposed as indicators of shear fracturing associated with fluid injection and circulation along major pre-existing
A Thermoelastic Hydraulic Fracture Design Tool for Geothermal Reservoir Development
Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Thus, knowledge of conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fracture are created in the reservoir using hydraulic fracturing. At times, the practice aims to create a number of parallel fractures connecting a pair of wells. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have set out to develop advanced thermo-mechanical models for design of artificial fractures and rock fracture research in geothermal reservoirs. These models consider the significant hydraulic and thermo-mechanical processes and their interaction with the in-situ stress state. Wellbore failure and fracture initiation is studied using a model that fully couples poro-mechanical and thermo-mechanical effects. The fracture propagation model is based on a complex variable and regular displacement discontinuity formulations. In the complex variable approach the displacement discontinuities are defined from the numerical solution of a complex hypersingular integral equation written for a given fracture configuration and loading. The fracture propagation studies include modeling interaction of induced fractures with existing discontinuities such as faults and joints. In addition to the fracture propagation studies, two- and three-dimensional heat extraction solution algorithms have been developed and used to estimate heat extraction and the variations of the reservoir stress with cooling. The numerical models have been developed in a user-friendly environment to create a tool for improving fracture design and investigating single or multiple fracture propagation in rock.
Ahmad Ghassemi
Mobil completes deep, tight, horizontal gas well in Germany
Science Conference Proceedings (OSTI)
A completion and fracturing program for stimulating a horizontal well in the ultra-tight Rotliegendes sand onshore Germany included casing design, completion fluid selection, overbalanced perforation, analysis of the stimulation treatment, design modification, zone and fracture isolation, well testing and acid stimulation. This paper reviews the field geology, the well design, casing design, describes the completion fluids, perforation techniques, fracture treatment, and methods for zone isolation.
Abou-Sayed, I.S.; Chambers, M.R. [Mobil E and P Technical Center, Dallas, TX (United States); Mueller, M.W. [Mobil Erdgas-Erdoel GmbH, Celle (Germany)
Mixed Integer Model Predictive Control of Multiple Shale Gas Wells.
?? Horizontal wells with multistage hydraulic fracturing are today the most important drilling technology for shale gas extraction. Considered unprofitable before, the production has now� (more)
Nordsveen, Espen T
RESERVOIR DEVELOPMENT edit Details Activities (1) Areas (1) Regions (0) Abstract: Thermal stimulation can be utilized to precondition a well to optimize fracturing and...
The stimulation of geothermal wells presents some new and challenging problems. Formation temperatures in the 300-600 F range can be expected. The behavior of stimulation fluids, frac proppants, and equipment at these temperatures in a hostile brine environment must be carefully evaluated before performance expectations can be determined. In order to avoid possible damage to the producing horizon of the formation, high temperature chemical compatibility between the in situ materials and the stimulation materials must be verified. Perhaps most significant of all, in geothermal wells the required techniques must be capable of bringing about the production of very large amounts of fluid. This necessity for high flow rates represents a significant departure from conventional petroleum well stimulation and demands the creation of very high near-wellbore permeability and/or fractures with very high flow conductivity.
Campbell, D. A.; Morris, C. W.; Sinclair, A. R.; Hanold, R. J.; Vetter, O. J.
The objective of the Field Fracturing Multi-Sites Project (M-Site) is to conduct field experiments and analyze data that will result in definitive determinations of hydraulic fracture dimensions using remote well and treatment well diagnostic techniques. In addition, experiments will be conducted to provide data that will resolve significant unknowns with regard to hydraulic fracture modeling, fracture fluid rheology and fracture treatment design. These experiments will be supported by a well-characterized subsurface environment as well as surface facilities and equipment conducive to acquiring high-quality data. It is anticipated that the project`s research advancements will provide a foundation for a fracture diagnostic service industry and hydraulic fracture optimization based on measured fracture response. The M-Site Project is jointly sponsored by the Gas Research Institute (GRI) and the US Department of Energy (DOE). The site developed for M-Site hydraulic fracture experimentation is the former DOE Multiwell Experiment (MWX) site located near Rifle, Colorado. The MWX project drilled three closely-spaced wells (MWX-1, MWX-2 and MWX-3) which were the basis for extensive reservoir analyses and tight gas sand characterizations in the blanket and lenticular sandstone bodies of the Mesaverde Group. The research results and background knowledge gained from the MWX project are directly applicable to research in the current M-Site Project.
Wilmer, R. [CER Corp., Las Vegas, NV (United States); Warpinski, N.R. [Sandia National Laboratories (United States); Wright, T.B. [Resources Engineering Systems (United States); Branagan, P.T. [Branagan & Associates (United States); Fix, J.E. [Fix & Associates (United States)
Wellness Program WELLNESS POINTS BANK
Wellness Program WELLNESS POINTS BANK Renew your commitment to health. Start again October 1, 2012 to your family and friends, too. Your health and well-being are also important to the University of Minnesota. As your employer, the University recognizes the value of investing in a comprehensive Wellness
Thomas, David D.
Production Wells | Open Energy Information
Production Wells Production Wells Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Production Wells Details Activities (13) Areas (13) Regions (0) NEPA(7) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Development Drilling Parent Exploration Technique: Development Drilling Information Provided by Technique Lithology: Drill cuttings are analyzed to determine lithology and mineralogy Stratigraphic/Structural: Fractures, faults, and geologic formations that the well passes through are identified and mapped. Hydrological: Identify aquifers, reservoir boundaries, flow rates, fluid pressure, and chemistry Thermal: Direct temperature measurements from within the reservoir Dictionary.png Production Wells:
Production Wells | Open Energy Information
Production Wells Production Wells (Redirected from Development Wells) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Production Wells Details Activities (13) Areas (13) Regions (0) NEPA(7) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Development Drilling Parent Exploration Technique: Development Drilling Information Provided by Technique Lithology: Drill cuttings are analyzed to determine lithology and mineralogy Stratigraphic/Structural: Fractures, faults, and geologic formations that the well passes through are identified and mapped. Hydrological: Identify aquifers, reservoir boundaries, flow rates, fluid pressure, and chemistry Thermal: Direct temperature measurements from within the reservoir
Well Deepening | Open Energy Information
Well Deepening Well Deepening Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Well Deepening Details Activities (5) Areas (3) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Development Drilling Parent Exploration Technique: Development Drilling Information Provided by Technique Lithology: Drill cuttings are analyzed to determine lithology and mineralogy Stratigraphic/Structural: Fractures, faults, and geologic formations that the well passes through are identified and mapped. Hydrological: Identify aquifers, reservoir boundaries, flow rates, fluid pressure, and chemistry Thermal: Direct temperature measurements from within the reservoir Dictionary.png Well Deepening:
The Site Characterization and Assessment Section of the Geosciences Department at Pacific Northwest Laboratory (PNL) has compiled a list of wells located on or near the Hanford Site. Information has been updated on wells existing from the days before construction of the Hanford Works to the present. This work was funded by the US Department of Energy (DOE). The list of wells will be used by DOE contractors who need condensed, tabular information on well location, construction, and completion dates. This report does not include data on lithologic logs and ground-water contamination. Moreover, the completeness of this list is limited because of new well construction and existing well modifications, which are continually under way. Despite these limitations, this list represents the most complete description possible of data pertaining to wells on or adjacent to the Hanford Site. 7 refs., 1 fig., 2 tabs.
McGhan, V.L.
Automatic hydraulic fracturing design for low permeability reservoirs using artificial intelligence
Science Conference Proceedings (OSTI)
The hydraulic fracturing technique is one of the major developments in petroleum engineering in the last two decades. Today, nearly all the wells completed in low permeability gas reservoirs require a hydraulic fracturing treatment in order to produce ...
Andrei Sergiu Popa / Shahab Mohaghegh
Field fracturing multi-sites project. Annual report, August 1, 1995--July 31, 1996
Science Conference Proceedings (OSTI)
The objective of the Field Fracturing Multi-Sites Project (M-Site) is to conduct experiments to definitively determine hydraulic fracture dimensions using remote well and treatment well diagnostic techniques. In addition, experiments are to be conducted to provide data that will resolve significant unknowns with regard to hydraulic fracture modeling, fracture fluid rheology and fracture treatment design. These experiments will be supported by a well-characterized subsurface environment, as well as surface facilities and equipment conducive to acquiring high-quality data. The primary Project goal is to develop a fully characterized, tight reservoir-typical, field-scale hydraulic fracturing test site to diagnose, characterize, and test hydraulic fracturing technology and performance. It is anticipated that the research work being conducted by the multi-disciplinary team of GRI and DOE contractors will lead to the development of a commercial fracture mapping tool/service.
A Rare Isolated Trapezoid Fracture
Toh S, Tsubo K, et al. An occult fracture of the trapezoiddue to concern for an occult fracture revealed a comminuted
Afifi, Negean; Lu, Jenny J
Hydraulic Fracturing in Particulate Materials .
??For more than five decades, hydraulic fracturing has been widely used to enhance oil and gas production. Hydraulic fracturing in solid materials (e.g., rock) has� (more)
Chang, Hong
Regulation of Hydraulic Fracturing (or lack thereof)
: "subsurface emplacement of fluids by well injection." 42 U.S.C. § 300h(d)(1). #12;UIC Program Requirements, EPA has concluded that the injection of hydraulic fracturing fluids into [coalbed methane] wells poses Water Act The federal Safe Drinking Water Act prohibits "underground injection" that is not authorized
Boufadel, Michel
Unsteady Flow Model for Fractured Gas Reservoirs
Science Conference Proceedings (OSTI)
Developing low permeability reservoirs is currently a big challenge to the industry. Because low permeability reservoirs are of low quality and are easily damaged, production from a single well is low, and there is unlikely to be any primary recovery. ... Keywords: Low permeability, Fractured well, Orthogonal transformation, Unsteady, Productivity
Li Yongming; Zhao Jinzhou; Gong Yang; Yao Fengsheng; Jiang Youshi
Hydraulic fracturing of jointed formations
Measured by volume, North America's largest hydraulic fracturing operations have been conducted at Fenton Hill, New Mexico to create geothermal energy reservoirs. In the largest operation 21,000 m/sup 3/ of water were injected into jointed granitic rock at a depth of 3.5 km. Microearthquakes induced by this injection were measured with geophones placed in five wells drilled into, or very close, to the reservoir, as well as 11 surface seismometers. The large volume of rock over which the microearthquakes were distributed indicates a mechanism of hydraulic stimulation which is at odds with conventional fracturing theory, which predicts failure along a plane which is perpendicular to the least compressive earth stress. A coupled rock mechanics/fluid flow model provides much of the explanation. Shear slippage along pre-existing joints in the rock is more easily induced than conventional tensile failure, particularly when the difference between minimum and maximum earth stresses is large and the joints are oriented at angles between 30 and 60 degrees to the principal earth stresses, and a low viscosity fluid like water is injected. Shear slippage results in local redistribution of stresses, which allows a branching, or dendritic, stimulation pattern to evolve, in agreement with the patterns of microearthquake locations. These results are qualitatively similar to the controversial process known as ''Kiel'' fracturing, in which sequential injections and shut-ins are repeated to create dendritic fractures for enhanced oil and gas recovery. However, we believe that the explanation is shear slippage of pre-existing joints and stress redistribution, not proppant bridging and fluid blocking as suggested by Kiel. 15 refs., 10 figs.
Murphy, H.D.; Fehler, M.C.
Science Conference Proceedings (OSTI)
Records describing wells located on or near the Hanford Site have been maintained by Pacific Northwest Laboratory and the operating contractor, Westinghouse Hanford Company. In support of the Ground-Water Surveillance Project, portions of the data contained in these records have been compiled into the following report, which is intended to be used by those needing a condensed, tabular summary of well location and basic construction information. The wells listed in this report were constructed over a period of time spanning almost 70 years. Data included in this report were retrieved from the Hanford Envirorunental Information System (HEIS) database and supplemented with information not yet entered into HEIS. While considerable effort has been made to obtain the most accurate and complete tabulations possible of the Hanford Site wells, omissions and errors may exist. This document does not include data on lithologic logs, ground-water analyses, or specific well completion details.
Chamness, M.A.; Merz, J.K.
Application of a 3D hydraulic-fracturing simulator for design of acid-fracturing treatments
Science Conference Proceedings (OSTI)
Field experience during 1989--90 shows that application of a 3D hydraulic-fracturing simulator increases success of acid-fracturing well treatments. Fracture extension can be limited to the oil-bearing pay, maximum lateral extension can be realized within the height constraint, and acid/rock contact time can be increased by a factor of between 3 and 30. Oil-production response can be improved over other stimulation designs while water-production response can be limited. These methods have been applied in mature waterfloods of the Permian Basin and Cedar Creek anticline.
Morgenthaler, L.N. (Shell Development Co., Houston, TX (United States))
Using Chemicals to Optimize Conformance Control in Fractured Reservoirs
The objectives of this project are: (1) to develop a capability to predict and optimize the ability of gels to reduce permeability to water more than that to oil or gas, (2) to develop procedures for optimizing blocking agent placement in wells where hydraulic fractures cause channeling problems, and (3) to develop procedures to optimize blocking agent placement in naturally fractured reservoirs. Work was directed at both injection wells and production wells and at vertical, horizontal, and highly deviated wells.
Seright, Randall; Liang, Jenn-Tai; Schrader, Richard; Hagstrom II, John; Wang, Ying; Kumar, Anand; Wavrik, Kathryn
Catalytic multi-stage liquefaction (CMSL)
Reported herein are the details and the results of laboratory and bench scale experiments that were conducted at Hydrocarbon Technologies, Inc. under DOE Contract No. DE-AC22-93PC92147 during the period of October 1, 1992, to December 31, 1995. The program results described herein build on the previous technology base and investigating additional methods to improve the economics of producing transportation fuels from coal. This included purely physical parameters, coal treatment and variation in solvent to coal ratio, the use of syngas to replace part of the hydrogen as the reducing gas, the use of dispersed catalyst in addition to and replacing the supported catalyst, and the co-processing of coal with plastic waste material. The overall objective of this program is to produce liquid fuels from direct coal liquefaction at a cost that is competitive with conventional fuels. The report includes the results of an economic assessment of the various process strategies that were evaluated during this program. A summary of the technical/economic evaluations is given in Volume I, Section II of this report. The experimental details of the eleven run of the program are given in Volume I, Section III and Volume II of this report. The details of the technical evaluations are given in the Volume III of the report.
Comolli, A.G.; Ganguli, P.; Karolkiewicz, W.F.; Lee, T.L.K.; Pradhan, V.R.; Popper, G.; Smith, T.; Stalzer, R.H.
and Multi-Stage Stochastic Programming Models
Dec 17, 2013 ... and it contains an analysis to quantify the difference in problem size for the ..... CPUs at 3.40 GHz (total 8 threads), 8 GB of RAM, and running�...
Adaptive multi-stage distance join processing
Science Conference Proceedings (OSTI)
A spatial distance join is a relatively new type of operation introduced for spatial and multimedia database applications. Additional requirements for ranking and stopping cardinality are often combined with the spatial distance join in on-line query ...
Hyoseop Shin; Bongki Moon; Sukho Lee
Fold Catastrophe Model of Fracture Propagation of Hydraulic Fracturing
Science Conference Proceedings (OSTI)
According to energy conservation from the destruction of rock catastrophe, a new calculation method of the length of fracture propagation in hydraulic fracturing is proposed, and assuming the crack extends to approximate ellipse, the width calculation ... Keywords: hydraulic fracture, fold catastrophe, fracture parameters
Zhaowan Chun; Wan Tingting; Ai Chi; Ju Guoshuai
Fracturing operations in a dry geothermal reservoir
Fracturing operations at the Fenton Hill, New Mexico, Hot Dry Rock (HDR) Geothermal Test Site initiated unique developments necessary to solve problems caused by an extremely harsh downhole environment. Two deep wells were drilled to approximately 15,000 ft (4.6 km); formation temperatures are in excess of 600/sup 0/F (315/sup 0/C). The wells were drilled during 1979 to 1981, inclined at 35 degrees, one above the other, and directionally drilled in an azimuthal direction orthogonal to the least principal in-situ crustal stress field. Hydraulic fracturing experiments to connect the two wells have used openhole packers, hydraulic jet notching of the borehole wall, cemented-in insolation liners and casing packers. Problems were encountered with hole drag, high fracture gradients, H/sub 2/S in vent back fluids, stress corrosion cracking of tubulars, and the complex nature of three-dimensional fracture growth that requires very large volumes of injected water. Two fractured zones have been formed by hydraulic fracturing and defined by close-in, borehole deployed, microseismic detectors. Initial operations were focused in the injection wellbore near total depth, where water injection treatments totalling 51,000 bbls (8100 m/sup 3/) were accomplished by pumping through a cemented-in 4-1/2 in. liner/PBR assembly. Retrievable casing packers were used to inject 26,000 bbls (4100 m/sup 3/) in the upper section of the open hole. Surface injection pressures (ISIP) varied from 4000 to 5900 psi (27 to 41 MPa) and the fracture gradient ranged from 0.7 to 0.96 psi/ft.
Rowley, J.C.; Pettitt, R.A.; Hendron, R.H.; Sinclair, A.R.; Nicholson, R.W.
Dual Permeability Modeling of Flow in a Fractured Geothermal Reservoir
A three dimensional fracture system synthesis and flow simulation has been developed to correlate drawdown characteristics measured in a geothermal well and to provide the basis for an analysis of tracer tests. A new dual permeability approach was developed which incorporates simulations at two levels to better represent a discrete fracture system within computer limitations. The first incorporates a discrete simulation of the largest fractures in the system plus distributed or representative element simulation of the smaller fractures. the second determines the representative element properties by discrete simulation of the smaller fractures. The fracture system was synthesized from acoustic televiewer data on the orientation and separation of three distinct fracture sets, together with additional data from the literature. Lognormal and exponential distributions of fracture spacing and radius were studied with the exponential distribution providing more reasonable results. Hydraulic apertures were estimated as a function of distance from the model boundary to a constant head boundary. Mean values of 6.7, 101 and 46 {micro}m were chosen as the most representative values for the three fracture sets. Recommendations are given for the additional fracture characterization needed to reduce the uncertainties in the model.
Miller, John D.; Allman, David W.
Dual permeability modeling of flow in a fractured geothermal reservoir
A three dimensional fracture system synthesis and flow simulation has been developed to correlate drawdown characteristics measured in a geothermal well and to provide the basis for an analysis of tracer tests. A new dual permeability approach was developed which incorporates simulations at two levels to better represent a discrete fracture system within computer limitations. The first incorporates a discrete simulation of the largest fractures in the system plus distributed or representative element stimulation of the smaller fractures. The second determines the representative element properties by discrete simulation of the smaller fractures. The fracture system was synthesized from acoustic televiewer data on the orientation and separation of three distinct fracture sets, together with additional data from the literature. Lognormal and exponential distributions of fracture spacing and radius were studied with the exponential distribution providing more reasonable results. Hydraulic apertures were estimated as a function of distance from the model boundary to a constant head boundary. Mean values of 6.7, 101 and 46 ..mu..m were chosen as the most representative values for the three fracture sets. Recommendations are given for the additional fracture characterization needed to reduce the uncertainties in the model. 20 refs., 6 figs.
Miller, J.D.; Allman, D.W.
C. and Fast, C. R. : Hydraulic Fracturing, Monograph Series,D. G. : "Mechanics of Hydraulic Fracturing," Trans. , AIME (Saunders, Calvin D. : "Hydraulic Fracturing: Fracture Flow
Authors, Various
The Effect of Proppant Size and Concentration on Hydraulic Fracture Conductivity in Shale Reservoirs
Hydraulic fracture conductivity in ultra-low permeability shale reservoirs is directly related to well productivity. The main goal of hydraulic fracturing in shale formations is to create a network of conductive pathways in the rock which increase the surface area of the formation that is connected to the wellbore. These highly conductive fractures significantly increase the production rates of petroleum fluids. During the process of hydraulic fracturing proppant is pumped and distributed in the fractures to keep them open after closure. Economic considerations have driven the industry to find ways to determine the optimal type, size and concentration of proppant that would enhance fracture conductivity and improve well performance. Therefore, direct laboratory conductivity measurements using real shale samples under realistic experimental conditions are needed for reliable hydraulic fracturing design optimization. A series of laboratory experiments was conducted to measure the conductivity of propped and unpropped fractures of Barnett shale using a modified API conductivity cell at room temperature for both natural fractures and induced fractures. The induced fractures were artificially created along the bedding plane to account for the effect of fracture face roughness on conductivity. The cementing material present on the surface of the natural fractures was preserved only for the initial unpropped conductivity tests. Natural proppants of difference sizes were manually placed and evenly distributed along the fracture face. The effect of proppant monolayer was also studied.
Kamenov, Anton
Poroelastic response of orthotropic fractured porous media
An algorithm is presented for inverting either laboratory or field poroelastic data for all the drained constants of an anisotropic (specifically orthotropic) fractured poroelastic system. While fractures normally weaken the system by increasing the mechanical compliance, any liquids present in these fractures are expected to increase the stiffness somewhat, thus negating to some extent the mechanical weakening influence of the fractures themselves. The analysis presented quantifies these effects and shows that the key physical variable needed to account for the pore-fluid effects is a factor of (1 - B), where B is Skempton's second coe#14;fficient and satisfies 0 {<=} #20; B < 1. This scalar factor uniformly reduces the increase in compliance due to the presence of communicating fractures, thereby stiffening the fractured composite medium by a predictable amount. One further goal of the discussion is to determine how many of the poroelastic constants need to be known by other means in order to determine the rest from remote measurements, such as seismic wave propagation data in the field. Quantitative examples arising in the analysis show that, if the fracture aspect ratio a{sub f} ~ 0.1 and the pore fluid is liquid water, then for several cases considered Skempton's B ~ 0:9, so the stiffening effect of the pore-liquid reduces the change in compliance due to the fractures by a factor 1-B ~ 0.1, in these examples. The results do however depend on the actual moduli of the unfractured elastic material, as well as on the pore-liquid bulk modulus, so these quantitative predictions are just examples, and should not be treated as universal results. Attention is also given to two previously unremarked poroelastic identities, both being useful variants of Gassmann's equations for homogeneous -- but anisotropic -- poroelasticity. Relationships to Skempton's analysis of saturated soils are also noted. The paper concludes with a discussion of alternative methods of analyzing and quantifying fluid-substitution behavior in poroelastic systems, especially for those systems having heterogeneous constitution.
Berryman, J.G.
Nonlinear Hertzian indentation fracture mechanics
Indentation cracking under blunt indenters is analyzed using nonlinear fracture mechanics. The usual assumptions of linear elastic fracture mechanics have been replaced with a nonlinear load vs load-point displacement curve while assuming the material is linear elastic. The load, the load-point displacement, and a function of the crack area have been related to the crack driving force, J, while assuming a cone fracture under the Hertzian sphere. Experimentally, it was found that the load-displacement curve during loading, cracking, and unloading is nonlinear. The crack length is empirically shown to be proportional to the load-point displacement for several indenters. The experimentally measured relations between indenter load, load-point displacement, and crack geometries are then analyzed with mechanical energy balances based on the similitude of crack lengths with load-point displacements. The Hertz hardness that describes the nonlinear load vs load-point displacement relation during cracking is derived on the constant J line in load-displacement space. Finally, well-known experimental expressions that relate load to crack length are shown to be indistinguishable from the load-point displacement analysis reported.
Burns, S.J.; Chia, K.Y. [Univ. of Rochester, NY (United States). Dept. of Mechanical Engineering
Regional Analysis And Characterization Of Fractured Aquifers In The
Analysis And Characterization Of Fractured Aquifers In The Analysis And Characterization Of Fractured Aquifers In The Virginia Blue Ridge And Piedmont Provinces Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Regional Analysis And Characterization Of Fractured Aquifers In The Virginia Blue Ridge And Piedmont Provinces Details Activities (1) Areas (1) Regions (0) Abstract: Areas related to low-temperature geothermal applications include the recognition of and exploration for deep fracture permeability in crystalline rocks. It is well known that the best currently available downhole techniques to identify the locations of fracture zones in crystalline rocks depend upon the measurement of some thermal parameter such as temperature or heat flow. The temperature-depth profiles and their derivatives provide a direct indication of those fracture zones that
DOE Geothermal well stimulation program
An effective stimulation treatment requires the interaction of four separate items: frac fluids, proppants, equipment, and planned and properly engineered schedules. While there are good fluid systems and proppants, only judicious combinations and a well thought out schedule which uses all of these materials and available equipment to best advantage is an optimum stimulation treatment. Generally, high flow rates and convective cooling can be used either with conventional (planar) fracturing or with a dendritic fracturing technique. Many of todays fluid systems have been tested to above 400/sup 0/F. Some fluids have survived quite well. Current tests on proppants have shown temperature sensitivities in sand; however, there are resin coated materials and sintered bauxite which are not temperature sensitive. (MHR)
Hanold, R.J.; Campbell, D.A.; Sinclair, A.R.
A monitoring well is described which includes: a conduit defining a passageway, the conduit having a proximal and opposite, distal end; a coupler connected in fluid flowing relationship with the passageway; and a porous housing borne by the coupler and connected in fluid flowing relation thereto. 8 figs.
Hubbell, J.M.; Sisson, J.B.
A monitoring well including a conduit defining a passageway, the conduit having a proximal and opposite, distal end; a coupler connected in fluid flowing relationship with the passageway; and a porous housing borne by the coupler and connected in fluid flowing relation thereto.
Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)
Effective fracture geometry obtained with large water sand ratio
Shale gas formation exhibits some unusual reservoir characteristics: nano-darcy matrix permeability, presence of natural fractures and gas storage on the matrix surface that makes it unique in many ways. It�s difficult to design an optimum fracture treatment for such formation and even more difficult is to describe production behavior using a reservoir model. So far homogeneous, two wing fracture, and natural fracture models have been used for this purpose without much success. Micro seismic mapping technique is used to measure the fracture propagation in real time. This measurement in naturally fractured shale formation suggests a growth of fracture network instead of a traditional two wing fractures. There is an industry wise consensus that fracture network plays an important role in determining the well productivity of such formations. A well with high density of fracture networks supposed to have better productivity. Shale formations have also exhibited production pattern which is very different from conventional or tight gas reservoir. Initial flow period is marked by steep decline in production while the late time production exhibits a slow decline. One of the arguments put for this behavior is linear flow from a bi-wing fractured well at early time and contribution of adsorbed gas in production at late time. However, bi-wing fracture geometry is not supported by the micro-seismic observation. A realistic model should include both the fracture network and adsorbed gas property. In this research we have proposed a new Power Law Permability model to simulate fluid flow from hydraulically fractured Shale formation. This model was first described by Valko & Fnu (2002) and used for analyzing acid treatment jobs. The key idea of this model is to use a power law permeability function that varies with the radial distance from well bore. Scaling exponent of this power law function has been named power law index. The permeability function has also been termed as secondary permeability. This work introduces the method of Laplace solution to solve the problem of transient and pseudo steady-state flow in a fracture network. Development and validation of this method and its extension to predict the pressure (and production) behaviour of fracture network were made using a novel technic. Pressure solution was then combined with material balance through productivity index to make production forecast. Reservoir rock volume affected by the fracture stimulation treatment that contributes in the production is called effective stimulated volume. This represents the extent of fracture network in this case. Barnett shale formation is a naturally fractured shale reservoir in Fort Worth basin. Several production wells from this formation was analysed using Power Law Model and it was found that wells productivity are highly dependent on stimulated volume. Apparently the wells flow under pseudo steady state for most part of their producing life and the effect of boundary on production is evident in as soon as one months of production. Due to short period of transient flow production from Barnett formations is expected to be largely independent of the relative distribution of permeability and highly dependent on the stimulated area and induced secondary permeability. However, an indirect relationship between permeability distribution and production rate is observed. A well with low power law index shows a better (more even) secondary permeability distribution in spatial direction, larger stimulated volume and better production. A comparative analysis between the new model and traditional fracture model was made. It was found that both models can be used successfully for history matching and production forecasting from hydraulically fractured shale gas formation.
Kumar, Amrendra
Relative permeability through fractures
The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood. In this study, nitrogen-water experiments were done on both smooth and rough parallel plates to determine the governing flow mechanism for fractures and the appropriate methodology for data analysis. The experiments were done using a glass plate to allow visualization of flow. Digital video recording allowed instantaneous measurement of pressure, flow rate and saturation. Saturation was computed using image analysis techniques. The experiments showed that gas and liquid phases flow through fractures in nonuniform separate channels. The localized channels change with time as each phase path undergoes continues breaking and reforming due to invasion of the other phase. The stability of the phase paths is dependent on liquid and gas flow rate ratio. This mechanism holds true for over a range of saturation for both smooth and rough fractures. In imbibition for rough-walled fractures, another mechanism similar to wave-like flow in pipes was also observed. The data from the experiments were analyzed using Darcy's law and using the concept of friction factor and equivalent Reynold's number for two-phase flow. For both smooth- and rough-walled fractures a clear relationship between relative permeability and saturation was seen. The calculated relative permeability curves follow Corey-type behavior and can be modeled using Honarpour expressions. The sum of the relative permeabilities is not equal one, indicating phase interference. The equivalent homogeneous single-phase approach did not give satisfactory representation of flow through fractures. The graphs of experimentally derived friction factor with the modified Reynolds number do not reveal a distinctive linear relationship.
Diomampo, Gracel, P.
Pressure transient analysis of fractured wells in shale reservoirs.
??In this study, an unconventional reservoir simulator is developed, which is based on a general black-oil simulator "MSFLOW". We incorporate several non-linear flow mechanisms (Klinkenberg� (more)
Wang, Cong
Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs
Science Conference Proceedings (OSTI)
The objectives of this project are to develop and test new techniques for creating extensive, conductive hydraulic fractures in unconventional tight gas reservoirs by statistically assessing the productivity achieved in hundreds of field treatments with a variety of current fracturing practices ranging from 'water fracs' to conventional gel fracture treatments; by laboratory measurements of the conductivity created with high rate proppant fracturing using an entirely new conductivity test - the 'dynamic fracture conductivity test'; and by developing design models to implement the optimal fracture treatments determined from the field assessment and the laboratory measurements. One of the tasks of this project is to create an 'advisor' or expert system for completion, production and stimulation of tight gas reservoirs. A central part of this study is an extensive survey of the productivity of hundreds of tight gas wells that have been hydraulically fractured. We have been doing an extensive literature search of the SPE eLibrary, DOE, Gas Technology Institute (GTI), Bureau of Economic Geology and IHS Energy, for publicly available technical reports about procedures of drilling, completion and production of the tight gas wells. We have downloaded numerous papers and read and summarized the information to build a database that will contain field treatment data, organized by geographic location, and hydraulic fracture treatment design data, organized by the treatment type. We have conducted experimental study on 'dynamic fracture conductivity' created when proppant slurries are pumped into hydraulic fractures in tight gas sands. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially; we pump proppant/frac fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. From such tests, we expect to gain new insights into some of the critical issues in tight gas fracturing, in particular the roles of gel damage, polymer loading (water-frac versus gel frac), and proppant concentration on the created fracture conductivity. To achieve this objective, we have designed the experimental apparatus to conduct the dynamic fracture conductivity tests. The experimental apparatus has been built and some preliminary tests have been conducted to test the apparatus.
Stephen Holditch; A. Daniel Hill; D. Zhu
Selection of fracture fluid for stimulating tight gas reservoirs
Essentially all producing wells drilled in tight gas sands and shales are stimulated using hydraulic fracture treatments. The development of optimal fracturing procedures, therefore, has a large impact on the long-term economic viability of the wells. The industry has been working on stimulation technology for more than 50 years, yet practices that are currently used may not always be optimum. Using information from the petroleum engineering literature, numerical and analytical simulators, surveys from fracturing experts, and statistical analysis of production data, this research provides guidelines for selection of the appropriate stimulation treatment fluid in most gas shale and tight gas reservoirs. This study takes into account various parameters such as the type of formation, the presence of natural fractures, reservoir properties, economics, and the experience of experts we have surveyed. This work provides a guide to operators concerning the selection of an appropriate type of fracture fluid for a specific set of conditions for a tight gas reservoir.
Malpani, Rajgopal Vijaykumar
Self-potential observations during hydraulic fracturing
and T. W. Keech (1977), Hydraulic fracture mapping usingpotential measurements during hydraulic fracturing of BunterSP Monitoring during hydraulic fracturing using the TG-2
Moore, Jeffrey R.; Glaser, Steven D.
Self-potential observations during hydraulic fracturing
potential measurements during hydraulic fracturing of BunterSP response during hydraulic fracturing. Citation: Moore, J.observations during hydraulic fracturing, J. Geophys. Res. ,
Moore, J R; Glaser, Steven D
Hydraulic Fracturing Poster | Department of Energy
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
Hydraulic Fracturing Poster Hydraulic Fracturing Poster Educational poster graphically displaying the key components of hydraulic fracturing. Teachers: If you would like hard...
Geothermal Reservoir Well Stimulation Program: technology transfer
Science Conference Proceedings (OSTI)
Each of the following types of well stimulation techniques are summarized and explained: hydraulic fracturing; thermal; mechanical, jetting, and drainhole drilling; explosive and implosive; and injection methods. Current stimulation techniques, stimulation techniques for geothermal wells, areas of needed investigation, and engineering calculations for various techniques. (MHR)
Not Available
Pressure transient analysis for naturally fractured reservoirs
Science Conference Proceedings (OSTI)
New ideas are presented for the interpretation of pressure transient tests for wells in naturally fractured reservoirs. This work is based on the transient matrix flow model formulated by de Swaan. The differences between this model and the Warren and Root model occur during the transition flow period. It is demonstrated that the behavior of a naturally fractured reservoir can be correlated by using three dimensionless parameters. It is established that regardless of matrix geometry the transition period might exhibit a straight line whose slope is equal to half the slope of the classical parallel semilog straight lines, provided the transient matrix linear flow is present. In addition, information is provided on the estimation of fracture area per unit matrix volume or matrix parameters from the transition period semilog straight line. It is shown that matrix geometry might be identified when pressure data are smooth. Field examples are included to illustrate the application and the validity of the theoretical results of this study.
Cinco-ley, H.; Samaniego, F.V.
TEMPORAL VARIATIONS OF FRACTURE DIRECTIONS AND FRACTURE DENSITIES IN THE TEMPORAL VARIATIONS OF FRACTURE DIRECTIONS AND FRACTURE DENSITIES IN THE COSO GEOTHERMAL FIELD FROM ANALYSES OF SHEAR-WAVE SPLITTING Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: TEMPORAL VARIATIONS OF FRACTURE DIRECTIONS AND FRACTURE DENSITIES IN THE COSO GEOTHERMAL FIELD FROM ANALYSES OF SHEAR-WAVE SPLITTING Details Activities (1) Areas (1) Regions (0) Abstract: This project aims to improve understanding of the subsurface fracture system in the Coso geothermal field, located in the east central California. We applied shear-wave splitting technique on a set of high quality, locally recorded microearthquake (MEQ) data. Four major fracture directions have been identified from the seismograms recorded by the permanent sixteen-station down-hole array: N10- 20W, NS, N20E, and N40-45E,
Science Conference Proceedings (OSTI)
The primary objective of this research was to improve completion and fracturing practices in gas reservoirs in marginal plays in the continental United States. The Bossier Play in East Texas, a very active tight gas play, was chosen as the site to develop and test the new strategies for completion and fracturing. Figure 1 provides a general location map for the Dowdy Ranch Field, where the wells involved in this study are located. The Bossier and other tight gas formations in the continental Unites States are marginal plays in that they become uneconomical at gas prices below $2.00 MCF. It was, therefore, imperative that completion and fracturing practices be optimized so that these gas wells remain economically attractive. The economic viability of this play is strongly dependent on the cost and effectiveness of the hydraulic fracturing used in its well completions. Water-fracs consisting of proppant pumped with un-gelled fluid is the type of stimulation used in many low permeability reservoirs in East Texas and throughout the United States. The use of low viscosity Newtonian fluids allows the creation of long narrow fractures in the reservoir, without the excessive height growth that is often seen with cross-linked fluids. These low viscosity fluids have poor proppant transport properties. Pressure transient tests run on several wells that have been water-fractured indicate a long effective fracture length with very low fracture conductivity even when large amounts of proppant are placed in the formation. A modification to the water-frac stimulation design was needed to transport proppant farther out into the fracture. This requires suspending the proppant until the fracture closes without generating excessive fracture height. A review of fracture diagnostic data collected from various wells in different areas (for conventional gel and water-fracs) suggests that effective propped lengths for the fracture treatments are sometimes significantly shorter than those predicted by fracture models. There was no accepted optimal method for conducting hydraulic fracturing in the Bossier. Each operator used a different approach. Anadarko, the most active operator in the play, had tested at least four different kinds of fracture treatments. The ability to arrive at an optimal fracturing program was constrained by the lack of adequate fracture models to simulate the fracturing treatment, and an inability to completely understand the results obtained in previous fracturing programs. This research aimed at a combined theoretical, experimental and field-testing program to improve fracturing practices in the Bossier and other tight gas plays.
Mukul M. Sharma
Geomechanical Development of Fractured Reservoirs During Gas Production
Within fractured reservoirs, such as tight gas reservoir, coupled processes between matrix deformation and fluid flow are very important for predicting reservoir behavior, pore pressure evolution and fracture closure. To study the coupling between gas desorption and rock matrix/fracture deformation, a poroelastic constitutive relation is developed and used for deformation of gas shale. Local continuity equation of dry gas model is developed by considering the mass conservation of gas, including both free and absorbed phases. The absorbed gas content and the sorption-induced volumetric strain are described through a Langmiur-type equation. A general porosity model that differs from other empirical correlations in the literature is developed and utilized in a finite element model to coupled gas diffusion and rock mass deformation. The dual permeability method (DPM) is implemented into the Finite Element Model (FEM) to investigate fracture deformation and closure and its impact on gas flow in naturally fractured reservoir. Within the framework of DPM, the fractured reservoir is treated as dual continuum. Two independent but overlapping meshes (or elements) are used to represent these kinds of reservoirs: one is the matrix elements used for deformation and fluid flow within matrix domain; while the other is the fracture element simulating the fluid flow only through the fractures. Both matrix and fractures are assumed to be permeable and can accomodate fluid transported. A quasi steady-state function is used to quantify the flow that is transferred between rock mass and fractures. By implementing the idea of equivalent fracture permeability and shape-factor within the transfer function into DPM, the fracture geometry and orientation are numerically considered and the complexity of the problem is well reduced. Both the normal deformation and shear dilation of fractures are considered and the stress-dependent fracture aperture can be updated in time. Further, a non-linear numerical model is constructed by implementing a poroviscoelastic model into the dual permeability (DPM)-finite element model (FEM) to investigate the coupled time-dependent viscoelastic deformation, fracture network evolution and compressible fluid flow in gas shale reservoir. The viscoelastic effect is addressed in both deviatoric and symmetric effective stresses to emphasize the effect of shear strain localization on fracture shear dilation. The new mechanical model is first verified with an analytical solution in a simple wellbore creep problem and then compared with the poroelastic solution in both wellbore and field cases.
Huang, Jian
Science Conference Proceedings (OSTI)
The second year of this three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The overall objectives of the study are to: (1) evaluate the reservoir conditions where fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. Simulation studies have been conducted with a dual porosity simulator capable of simulating the performance of vertical and horizontal wells. Each simulation model has been initialized with properties typical of the Austin Chalk reservoir in Pearsall Field, Texas. During year one, simulations of both vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure charge. The results confirmed that horizontal wells could increase both rate of oil recovery and total oil recovery from naturally fractured reservoirs. During the second year the performances of the same vertical and horizontal wells were evaluated with the assumption that fracture permeability was a function of reservoir pressure. This required repetition of most of the natural depletion cases simulated in year one while invoking the pressure-sensitive fracture permeability option. To investigate sensitivity to in situ stress, two stress conditions were simulated for each primary variable. The water injection cases, begun in year one, were extended to include most of the reservoir parameters investigated for natural depletion, including fracture permeability as a function of net stress and the use of horizontal wells. The results thus far confirm that pressure-sensitive fractures degrade well performance and that the degradation is reduced by water injection pressure maintenance. Furthermore, oil recovery can be significantly increased by water injection pressure maintenance.
Not Available
Subsurface fracture mapping from geothermal wellbores. Final report
To advance the state-of-the-art in Hot Dry Rock technology, and evaluation is made of (1) the use of both electromagnetic and acoustic radar to map far-field fractures, (2) the use of more than twenty different conventional well logging tools to map borehole-fracture intercepts, (3) the use of magnetic dipole ranging to determine the relative positions of the injection well and the production well within the fractured zone, (4) the use of passive microseismic methods to determine the orientation and extent of hydraulic fractures, and (5) the application of signal processing techniques to fracture mapping including tomography, holography, synthetic aperture, image reconstruction, and the relative importance of phase and amplitude information. It is found that according to calculations, VHF backscatter radar has the potential for mapping fractures within a distance of 50 +- 20 meters from the wellbore. A new technique for improving fracture identification is presented. The range of acoustic radar is five to seven times greater than that of VHF radar when compared on the basis of equal resolution, i.e., equal wavelengths. Analyses of extant data indicate that when used synergistically the (1) caliper, (2) resistivity dipmeter, (3) televiewer, (4) television, (5) impression packer, and (6) acoustic transmission are useful for mapping borehole-fracture intercepts. A new model of hydraulic fracturing is presented which indicates that a hydraulic fracture is dynamically unstable; consequently, improvements in locating the crack tip may be possible. The importance of phase in signal processing is stressed and those techniques which employ phase data are emphasized for field use.
Hartenbaum, B.A.; Rawson, G.
Real-time and post-frac' 3-D analysis of hydraulic fracture treatments in geothermal reservoirs
Economic power production from Hot Dry Rock (HDR) requires the establishment of an efficient circulation system between wellbores in reservoir rock with extremely low matrix permeability. Hydraulic fracturing is employed to establish the necessary circulation system. Hydraulic fracturing has also been performed to increase production from hydrothermal reservoirs by enhancing the communication with the reservoir's natural fracture system. Optimal implementation of these hydraulic fracturing applications, as with any engineering application, requires the use of credible physical models and the reconciliation of the physical models with treatment data gathered in the field. Analysis of the collected data has shown that 2-D models and 'conventional' 3-D models of the hydraulic fracturing process apply very poorly to hydraulic fracturing in geothermal reservoirs. Engineering decisions based on these more 'conventional' fracture modeling techniques lead to serious errors in predicting the performance of hydraulic fracture treatments. These errors can lead to inappropriate fracture treatment design as well as grave errors in well placement for hydrothermal reservoirs or HDR reservoirs. This paper outlines the reasons why conventional modeling approaches fall short, and what types of physical models are needed to credibly estimate created hydraulic fracture geometry. The methodology of analyzing actual measured fracture treatment data and matching the observed net fracturing pressure (in realtime as well as after the treatment) is demonstrated at two separate field sites. Results from an extensive Acoustic Emission (AE) fracture diagnostic survey are also presented for the first case study aS an independent measure of the actual created hydraulic fracture geometry.
Wright, C.A.; Tanigawa, J.J.; Hyodo, Masami; Takasugi, Shinji
Breakthrough in fracture mechanics
Fracture mechanics, the science of calculating material characteristics, stress, and flaws in plant equipment to evaluate structural integrity, usually spares the owners of nuclear power plants unnecessary expense. Instead of replacing equipment prematurely or waiting for costly, unscheduled materials failures that can take months to repair and cost thousands of dollars a day for replacement power, utilities use fracture mechanics techniques to carefully consider their options. If analyses show repair is unnecessary, plant operation can confidently be resumed. If repair is required, it can either be done immediately or, if deferrable, be scheduled for a later, more convenient outage.
Lihach, N.
Science Conference Proceedings (OSTI)
The Environmental Restoration Technology Section (ERTS) of the Savannah River National Laboratory (SRNL) conducted pilot scale testing to evaluate the effectiveness of using hydraulic fracturing as a means to improve soil vapor extraction (SVE) system performance. Laboratory and field research has shown that significant amounts of solvents can be entrapped in low permeability zones by capillary forces and removal by SVE can be severely limited due to low flow rates, mass transfer resistance of the hydrophobic compounds by trapped interparticle water, and diffusion resistance. Introducing sand-filled fractures into these tight zones improves the performance of SVE by (1) increasing the overall permeability of the formation and thereby increasing SVE flow rates, (2) shortening diffusion pathways, and (3) increasing air permeability by improving pore water removal. The synergistic effect of the fracture well completion methods, fracture and flow geometry, and pore water removal appears to increase the rate of solvent mass removal over that of increasing flow rate alone. A field test was conducted where a conventional well in the SRS Upland Unit was tested before and after hydraulic fracturing. ERTS teamed with Clemson University through the South Carolina University and Education Foundation (SCUREF) program utilizing their expertise in fracturing and fracture modeling. The goals of the fracturing pilot testing were to evaluate the following: (1) The effect of hydraulic fractures on the performance of a conventional well. This was the most reliable way to remove the effects of spatial variations in permeability and contaminant distribution on relative well performance. It also provided data on the option of improving the performance of existing wells using hydraulic fractures. (2) The relative performance of a conventional SVE well and isolated hydraulic fractures. This was the most reliable indicator of the performance of hydraulic fractures that could be created in a full-scale implementation. The SVE well, monitoring point arrays and four fracturing wells were installed and the well testing has been completed. Four fractures were successfully created the week of July 25, 2005. The fractures were created in an open area at the bottom of steel well casing by using a water jet to create a notch in the soil and then injecting a guar-sand slurry into the formation. The sand-filled fractures increase the effective air permeability of the subsurface formation diffusion path lengths for contaminant removal. The primary metrics for evaluation were an increase in SVE flow rates in the zone of contamination and an increase in the zone of influence. Sufficient testing has been performed to show that fracturing in the Upland Unit accelerates SVE solvent remediation and fracturing can increase flow rates in the Upland Unit by at least one order of magnitude.
Riha, B
Automatic hydraulic fracturing design for low permeability reservoirs using artificial intelligence.
??The hydraulic fracturing technique is one of the major developments in petroleum engineering in the last two decades. Today, nearly all the wells completed in� (more)
Popa, Sergui Andrei, 1970-
Enthalpy transients in fractured two-phase geothermal systems
Numerical modeling techniques are used to study the changes in flowing enthalpy of fluids produced from a well completed in a fractured two-phase geothermal reservoir. Complex interactions between different fracture and porous matrix parameters control the enthalpy transients. The results show that the flowing enthalpy is most sensitive to the characteristics of the relative permeability curves, the magnitude of the matrix permeability and the effective fracture porosity. Other parameters such as the thermal conductivity and fracture spacing also significantly affect the flowing enthalpy. In spite of the complex phenomena associated with enthalpy transients in fractured two-phase systems, it is possible to infer useful information about the producing geothermal reservoirs from field data. 15 refs., 13 figs., 2 tabs.
Lippmann, M.J.; Bodvarsson, G.S.; Gaulke, S.W.
Rigid Body Simulation with Local Fracturing Effects
Science Conference Proceedings (OSTI)
Focusing on the real-time and interactive ability features in the Virtual Reality application, we propose a fracture pattern based on local fracture mechanism. Taking advantage of the experience analysis or the offline computation verified fracture characteristic, ... Keywords: Rigid Body, pre-fracture, fracture pattern, local fracture, dynamics
Wu Bo; Zeng Liang; Wu Yagang
Fracture characteristics and their relationships to producing zones in deep
source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon » Fracture characteristics and their relationships to producing zones in deep wells, Raft River geothermal area Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Book: Fracture characteristics and their relationships to producing zones in deep wells, Raft River geothermal area Details Activities (1) Areas (1) Regions (0) Abstract: Fracture characteristics in the sedimentary and metamorphic rocks in the Raft River KGRA of Idaho are analyzed using geological, hydrological and borehole geophysical data from five deep geothermal production wells. Particular emphasis is placed on fracture identification using borehole
Hydraulic fracture experiments in GT-1 and GT-2
Hydraulic fracturing experiments were conducted in granite rock, at temperatures near 100 and 150/sup 0/C, in two wells 0.785 km (2575 ft) and 1.98 km (6500 ft) deep near Los Alamos, New Mexico. No unusual difficulty was observed in fracturing crystalline rock hydraulically. The apparent surface energy (energy required to create new fracture surface by breaking the rock) was measured as 100 J/m/sup 2/. Orientation of the deeper fracture was measured as N35/sup 0/E (+-5/sup 0/). The fraction of fluid injected into the rock that could be recovered at hydrostatic surface pressure was measured. The efficiency of recovery was as high as 92 percent after the fracture impedance was lowered by ''propping'' the fracture with sand. Permeability of the rock over the face of the fracture was compatible with laboratory measurements (10/sup -7/ to 10/sup -8/ darcys). Downhole pressures required to extend the fractures were about 150 and 340 bars (2175 and 4900 psi), respectively.
Aamodt, R.L.
Physical model studies of dispersion in fracture systems
The purposes of the laboratory-scale fracture network experiments are to study mechanisms controlling solute transport under conditions of known fracture parameters, to evaluate injection-backflow test procedures under conditions of known reservoir parameters, and to acquire data for validation of numerical models. Validation of computer codes against laboratory data collected under controlled conditions provides reassurance that the codes deal with important processes in a realistic manner. Preliminary simulations of the dual-permeability physical model have been made using the FRACSL reservoir code. These simulations permit locating electrodes and piezometers in the most advantageous positions to record tracer migration and pressure response. Much of the physical modeling effort this year was oriented towards validating the particle tracking algorithm used in FRACSL, and developing a better theoretical understanding of transport processes in fractures. Experiments were conducted in single fractures and single fracture junctions, and data on tracer migration collected. The Prickett, Naymik, and Lonnquist Random Walk aquifer simulation program has been modfied to simulate flow in single fractures. The particle tracking algorithm was also used to simulate infinite parallel plates under conditions where analytical solutions to the transport equation could be derived. The first case is for zero diffusion in the fracture, and transport based on a parabolic velocity profile. The second case is for diffusion homogenizing the tracer solution across the fracture. The particle tracking algorithm matched both analytical solutions quite well, with the same grid for both simulations. 48 refs., 41 figs., 2 tabs.
Hull, L.C.
Modeling the fracture of ice sheets on parallel computers.
The objective of this project is to investigate the complex fracture of ice and understand its role within larger ice sheet simulations and global climate change. At the present time, ice fracture is not explicitly considered within ice sheet models due in part to large computational costs associated with the accurate modeling of this complex phenomena. However, fracture not only plays an extremely important role in regional behavior but also influences ice dynamics over much larger zones in ways that are currently not well understood. Dramatic illustrations of fracture-induced phenomena most notably include the recent collapse of ice shelves in Antarctica (e.g. partial collapse of the Wilkins shelf in March of 2008 and the diminishing extent of the Larsen B shelf from 1998 to 2002). Other fracture examples include ice calving (fracture of icebergs) which is presently approximated in simplistic ways within ice sheet models, and the draining of supraglacial lakes through a complex network of cracks, a so called ice sheet plumbing system, that is believed to cause accelerated ice sheet flows due essentially to lubrication of the contact surface with the ground. These dramatic changes are emblematic of the ongoing change in the Earth's polar regions and highlight the important role of fracturing ice. To model ice fracture, a simulation capability will be designed centered around extended finite elements and solved by specialized multigrid methods on parallel computers. In addition, appropriate dynamic load balancing techniques will be employed to ensure an approximate equal amount of work for each processor.
Waisman, Haim (Columbia University); Bell, Robin (Columbia University); Keyes, David (Columbia University); Boman, Erik Gunnar; Tuminaro, Raymond Stephen
Evaluation of fracture treatments using a layered-reservoir description: Field examples
Science Conference Proceedings (OSTI)
This paper presents a practical analysis technique to determine actual fracture geometry and proppant profile using a three-dimensional (3D) hydraulic-fracturing simulator. The hydraulic-fracturing model used in this study considers the variation of in-situ stress, Young`s modulus, Poisson`s ratio, and net pay thickness in the productive interval. When the method is applied, the results from the fracture propagation model conform well with the results the authors obtain from pressure-buildup and production-data analyses. This study analyzed hydraulic-fracturing treatments from several wells in the Vicksburg formation of the McAllen Ranch area in south Texas. The authors have provided guidelines to properly describe the treatment interval, how to use this information in the analysis of such fracture treatments, and how to confirm the results using pressure-transient tests and production-data analyses. This paper presents examples illustrating that a detailed description of the reservoir layers is essential to properly evaluate hydraulic-fracture treatments. For the example wells presented in this paper, post-fracture-production and pressure-transient data were available. The authors have analyzed production and pressure-transient data to estimate permeability and fracture half-length. The values of fracture half-length used to analyze the production data matched closely with those predicted by the fracture model.
Rahim, Z.; Holditch, S.A.; Zuber, M.D. [Holditch and Associates Inc., College Station, TX (United States); Buehring, D.R.
The first of a three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The objectives of the study are to (1) evaluate the reservoir conditions where fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. Simulation studies were conducted with a dual porosity simulator capable of simulating the performance of vertical and horizontal wells. Each simulator was initialized using properties typical of the Austin Chalk reservoir in Pearsall Field, Texas. Simulations of both vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure change. Sensitivity runs indicate that the simulator is predicting the effects of critical reservoir parameters in a logical and consistent manner. The results to-date confirm that horizontal wells can increase both oil recovery rate and total oil recovery from naturally fractured reservoirs. The year one simulation results will provide the baseline for the ongoing study which will evaluate the performance degradation caused by the sensitivity of fracture permeability to pressure change, and investigate fluid injection pressure maintenance as a means to improve oil recovery performance. The study is likely to conclude that fracture closure decreases oil recovery and that pressure support achieved through fluid injection could be beneficial in improving recovery.
Not Available
Stimulation Technologies for Deep Well Completions
The Department of Energy (DOE) is sponsoring the Deep Trek Program targeted at improving the economics of drilling and completing deep gas wells. Under the DOE program, Pinnacle Technologies is conducting a study to evaluate the stimulation of deep wells. The objective of the project is to assess U.S. deep well drilling & stimulation activity, review rock mechanics & fracture growth in deep, high pressure/temperature wells and evaluate stimulation technology in several key deep plays. An assessment of historical deep gas well drilling activity and forecast of future trends was completed during the first six months of the project; this segment of the project was covered in Technical Project Report No. 1. The second progress report covers the next six months of the project during which efforts were primarily split between summarizing rock mechanics and fracture growth in deep reservoirs and contacting operators about case studies of deep gas well stimulation.
Many basins in the Rocky Mountains contain naturally fractured gas reservoirs. Production from these reservoirs is controlled primarily by the shape, orientation and concentration of the natural fractures. The detection of gas filled fractures prior to drilling can, therefore, greatly benefit the field development of the reservoirs. The objective of this project was to test and verify specific seismic methods to detect and characterize fractures in a naturally fractured reservoir. The Upper Green River tight gas reservoir in the Uinta Basin, Northeast Utah was chosen for the project as a suitable reservoir to test the seismic technologies. Knowledge of the structural and stratigraphic geologic setting, the fracture azimuths, and estimates of the local in-situ stress field, were used to guide the acquisition and processing of approximately ten miles of nine-component seismic reflection data and a nine-component Vertical Seismic Profile (VSP). Three sources (compressional P-wave, inline shear S-wave, and cross-line, shear S-wave) were each recorded by 3-component (3C) geophones, to yield a nine-component data set. Evidence of fractures from cores, borehole image logs, outcrop studies, and production data, were integrated with the geophysical data to develop an understanding of how the seismic data relate to the fracture network, individual well production, and ultimately the preferred flow direction in the reservoir. The multi-disciplinary approach employed in this project is viewed as essential to the overall reservoir characterization, due to the interdependency of the above factors.
in modeling multiphase flow in porous and fractured media,multiphase tracer transport in heterogeneous fractured porousof multiphase flow through fractured or porous media.
Wu, Yu-Shu; Pan, Lehua; Pruess, Karsten
in modeling multiphase flow in porous and fractured media,multiphase tracer transport in heterogeneous fractured porousof multiphase flow through fractured or porous media. 3.
Wu, Yu-Shu; Pruess, Karsten
Using Chemicals to Optimize Conformance Control in Fractured Reservoirs
This report describes work performed during the third and final year of the project, Using Chemicals to Optimize Conformance Control in Fractured Reservoirs. This research project had three objectives. The first objective was to develop a capability to predict and optimize the ability of gels to reduce permeability to water more than that to oil or gas. The second objective was to develop procedures for optimizing blocking agent placement in wells where hydraulic fractures cause channeling problems. The third objective was to develop procedures to optimize blocking agent placement in naturally fractured reservoirs.
Seright, Randall S.; Liang, Jenn-Tai; Schrader, Richard; Hagstrom II, John; Wang, Ying; Kumar, Ananad; Wavrik, Kathryn
A fracture network model for water flow and solute transport
This paper summarizes code development work and sample calculations for FRACNET, a two-dimensional steady state simulator of fluid flow and solute transport in fractured porous media. The model analyzes flow and transport by generating a fracture network based on statistical characteristics of fractures obtained from well logs and other data. After a network is generated, flow and tracer transport are computed for appropriate boundary conditions and wellbore source/sink terms. In addition, for a given realization, the code can be used to indicate whether the medium can be treated as an equivalent porous medium. 18 refs., 7 figs.
Robinson, B.A.
Evaluation of rock/fracture interactions during steam injection through vertical hydraulic fractures
The design, results, and analysis of a steamdrive pilot in the South Belridge diatomite, Kern County, California, are reviewed. Pilot results demonstrate that steam can be injected across a 1,000-ft-tall diatomite column using hydraulically fractured wells and that significant oil is produced in response to steaming. A computationally simple numerical model is proposed and used to analyze reservoir heating and volumetric sweep by steam. Results from the analysis show that hydraulic fractures undergoing steam injection can be dynamic and asymmetrical.
Kovscek, A.R. [Stanford Univ., CA (United States); Johnston, R.M. [CalResources LLC, Bakersfield, CA (United States); Patzek, T.W. [Univ. of California, Berkeley, CA (United States)
Evaluation of subsurface fracture geometry using fluid pressure response to
subsurface fracture geometry using fluid pressure response to subsurface fracture geometry using fluid pressure response to solid earth tidal strain Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Evaluation of subsurface fracture geometry using fluid pressure response to solid earth tidal strain Details Activities (1) Areas (1) Regions (0) Abstract: The nature of solid earth tidal strain and surface load deformation due to the influence of gravitational forces and barometric pressure loading are discussed. The pore pressure response to these types of deformation is investigated in detail, including the cases of a confined aquifer intersected by a well and a discrete fracture intersected by a well. The integration of the tidal response method with conventional pump tests in order to independently calculate the hydraulic parameters of the
Single-Well and Cross-Well Resistivity | Open Energy Information
Single-Well and Cross-Well Resistivity Single-Well and Cross-Well Resistivity Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Single-Well and Cross-Well Resistivity Details Activities (14) Areas (13) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Downhole Techniques Exploration Sub Group: Well Log Techniques Parent Exploration Technique: Well Log Techniques Information Provided by Technique Lithology: Identify different lithological layers, rock composition, mineral, and clay content Stratigraphic/Structural: -Fault and fracture identification -Rock texture, porosity, and stress analysis -determine dip and structural features in vicinity of borehole -Detection of permeable pathways, fracture zones, faults Hydrological: Resistivity influenced by porosity, grain size distribution, permeability, fluid saturation, fluid type and phase state of the pore water
High energy gas fracture experiments in liquid-filled boreholes: potential geothermal application
High Energy Gas Fracturing is a tailored pulse fracturing technique which uses propellants to obtain controlled fracture initiation and extension. Borehole pressurization rates can be tailored, by suitable choice of propellants, to produce four or eight fractures radiating from the wellbore. High Energy Gas Fracture (HEGF) research is conducted at DOE's Nevada Test Site (NTS) in a tunnel complex where experiments can be done under realistic in situ stress conditions (1400 psi (9.7 MPa) overburden stress). Pressure measurements are made in the test borehole during all fracturing experiments. Experiments are mined back to provide direct observation of fracturing obtained. The initial objective of HEGF research was to develop multiple fracturing technology for application in gas well stimulation. HEGF research at NTS and in Devonian shale demonstration tests has resulted in a completed technology for multiple fracturing in uncased, liquid-free wellbores. Current resarch is directed toward extending the technique to liquid-filled boreholes for application in geothermal in addition to gas and oil wells. For liquid-free boreholes, multiple fracturing is specified in terms of pressure risetime required for a given borehole diameter. Propellants are mixed to achieve the desired risetime using a semiempirical mixing equation. The same techniques were successfully applied to fracturing in liquid-filled wellbores. However, the addition of liquid in the borehole results in a significantly more complicated fracturing behavior. Hydrodynamic effects are significant. Multiple fractures are initiated but only some propagated. Multiple- and hydraulic-type fracturing and wellbore crushing have been observed in the same experiment. The potential of using HEGB for geothermal well stimulation has been demonstrated through the present experiments. 18 refs., 40 figs., 4 tabs.
Cuderman, J.F.; Chu, T.Y.; Jung, J.; Jacobson, R.D.
Numerical Investigation of Interaction Between Hydraulic Fractures and Natural Fractures
Hydraulic fracturing of a naturally-fractured reservoir is a challenge for industry, as fractures can have complex growth patterns when propagating in systems of natural fractures in the reservoir. Fracture propagation near a natural fracture (NF) considering interaction between a hydraulic fracture (HF) and a pre-existing NF, has been investigated comprehensively using a two dimensional Displacement Discontinuity Method (DDM) Model in this thesis. The rock is first considered as an elastic impermeable medium (with no leakoff), and then the effects of pore pressure change as a result of leakoff of fracturing fluid are considered. A uniform pressure fluid model and a Newtonian fluid flow model are used to calculate the fluid flow, fluid pressure and width distribution along the fracture. Joint elements are implemented to describe different NF contact modes (stick, slip, and open mode). The structural criterion is used for predicting the direction and mode of fracture propagation. The numerical model was used to first examine the mechanical response of the NF to predict potential reactivation of the NF and the resultant probable location for fracture re-initiation. Results demonstrate that: 1) Before the HF reaches a NF, the possibility of fracture re-initiation across the NF and with an offset is enhanced when the NF has weaker interfaces; 2) During the stage of fluid infiltration along the NF, a maximum tensile stress peak can be generated at the end of the opening zone along the NF ahead of the fluid front; 3) Poroelastic effects, arising from fluid diffusion into the rock deformation can induce closure and compressive stress at the center of the NF ahead of the HF tip before HF arrival. Upon coalescence when fluid flows along the NF, the poroelastic effects tend to reduce the value of the HF aperture and this decreases the tension peak and the possibility of fracture re-initiation with time. Next, HF trajectories near a NF were examined prior to coalesce with the NF using different joint, rock and fluid properties. Our analysis shows that: 1) Hydraulic fracture trajectories near a NF may bend and deviate from the direction of the maximum horizontal stress when using a joint model that includes initial joint deformation; 2) Hydraulic fractures propagating with higher injection rate or fracturing fluid of higher viscosity propagate longer distance when turning to the direction of maximum horizontal stress; 3) Fracture trajectories are less dependent on injection rate or fluid viscosity when using a joint model that includes initial joint deformation; whereas, they are more dominated by injection rate and fluid viscosity when using a joint model that excludes initial joint deformation.
Xue, Wenxu
Injection and energy recovery in fractured geothermal reservoirs
Numerical studies of the effects of injection on the behavior of production wells completed in fractured two-phase geothermal reservoirs are presented. In these studies the multiple-interacting-continua (MINC) method is employed for the modeling of idealized fractured reservoirs. Simulations are carried out for a five-spot well pattern with various well spacings, fracture spacings, and injection fractions. The production rates from the wells are calculated using a deliverability model. The results of the studies show that injection into two-phase fractured reservoirs increases flow rates and decreases enthalpies of producing wells. These two effects offset each other so that injection tends to have small effects on the usable energy output of production wells in the short term. However, if a sufficiently large fraction of the produced fluids is injected, the fracture system may become liquid-filled and an increased steam rate is obtained. Our studies show that injection greatly increases the long-term energy output from wells, as it helps extract heat from the resrvoir rocks. If a high fraction of the produced fluids is injected, the ultimate energy recovery will increase manyfold.
Bodvarsson, G.S.; Pruess, K.; O'Sullivan, M.J.
Laboratory study of hydraulic fracturing pressure data?Howevaluation of hydraulic fracturing stress measurementreopening during hydraulic fracturing stress determinations.
Rutqvist, Jonny; Tsang, Chin-fu; Stephansson, Ove
Fracture-injection/falloff sequences are routinely used as pre-frac well tests to estimate reservoir pressure and transmissibility, but the current interpretation methods are limited to analyzing specific and very small portions of the pressure falloff data. To remove the current limitations, new analytical fractureinjection/ falloff models are developed that account for fracture propagation, fracture closure, and after fracture closure diffusion. A fracture-injection/falloff differs from a conventional injection/falloff sequence in that pressure during the injection is sufficient to initiate and propagate a hydraulic fracture. By considering fracture propagation as time-dependent storage, three new models are presented for a fractureinjection/ falloff sequence in a well in an infinite slab reservoir with a single vertical fracture created during the injection and with variable fracture and wellbore storage as follows: �? Equivalent propagating-fracture and before-fracture-closure storage with constant after-fractureclosure storage. �? Time-dependent propagating-fracture storage, constant before-closure storage, and constant afterclosure storage. �? Time-dependent propagating-fracture storage, constant before-closure storage with linear flow from the fracture, and constant wellbore storage and skin with after-closure radial flow. When a fracture-injection can be considered as occurring instantaneously, limiting-case solutions of the new fracture-injection/falloff models suggest the observed pressure difference can be integrated to generate an equivalent pressure difference if the rate were constant. Consequently, a fractureinjection/ falloff sequence can be analyzed with constant-rate, variable-storage type curves. The new fracture-injection/falloff theory is also extended to allow for a fracture-injection in a reservoir containing an existing conductive hydraulic fracture. The new multiple-fracture fracture-injection/falloff model forms the basis of a new refracture-candidate diagnostic test that uses characteristic variable-storage behavior to qualitatively diagnose a pre-existing fracture retaining residual width and to determine if a preexisting fracture is damaged. A quantitative analysis methodology is also proposed that uses a new pressure-transient solution for a well in an infinite-slab reservoir producing through multiple arbitrarilyoriented finite- or infinite-conductivity fractures.
Craig, David Paul
Experimental Determination of Tracer Dispersivity in Fractures
Reinjection of waste hot water is commonly practiced in most geothermal fields, primarily as a means of disposal. Surface discharge of these waste waters is usually unacceptable due to the resulting thermal and chemical pollution. Although reinjection can help to main reservoir pressure and fluid volume, in some cases a decrease in reservoir productivity has been observed. This is caused by rapid flow of the reinjected water through fractures connecting the injector and producers. As a result, the water is not sufficiently heated by the reservoir rock, and a reduction in enthalpy of the produced fluids is seen. Tracer tests have proven to be valuable to reservoir engineers for the design of a successful reinjection program. By injecting a slug of tracer and studying the discharge of surrounding producing wells, an understanding of the fracture network within a reservoir can be provided. In order to quantify the results of a tracer test, a model that accurately describes the mechanisms of tracer transport is necessary. One such mechanism, dispersion, is like a smearing out of a tracer concentration due to the velocity gradients over the cross section of flow. If a dispersion coefficient can be determined from tracer test data, the fracture width can be estimated. The purpose of this project was to design and construct an apparatus to study the dispersion of a chemical tracer in flow through a fracture.
Gilardi, J.; Horns, R.N.
Modeling studies to evaluate performance of the horizontal wells completed in shale.
??The results of the modeling studies to determine the production performance of multiple fractured horizontal wells completed in shale formation has been summarized in this� (more)
Belyadi, Abbas.
Location of hydraulic fractures using microseismic techniques
Microearthquakes with magnitudes ranging between -6 and -2 have been observed in three successive massive injections of water at the Hot Dry Rock Geothermal Energy demonstration site at Fenton Hill, New Mexico. The injection was part of a program to increase the heat transfer area of hydraulic fractures and to decrease the flow-through impedance between wells. The microearthquakes were used in mapping the location of the extended hydraulic fractures. A downhole triaxial system positioned approximately 200 m vertically above the injection point in a shut-in production well was used for detection. The microearthquakes occurred in a north-northwest striking zone 400 m in length passing through the injection point. During a third substantially larger injection, microearthquakes occurred in a dispersed volume at distances as great as 800 m from the zone active in the first two injections.
Albright, J.A.; Pearson, C.F.
Naturally fractured tight gas reservoir detection optimization
Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.
Procedure for estimating fracture energy from fracture surface roughness
The fracture energy of a material is determined by first measuring the length of a profile of a section through a fractured surface of the material taken on a plane perpendicular to the mean plane of that surface, then determining the fractal dimensionality of the surface. From this, the yield strength of the material, and the Young's Modulus of that material, the fracture energy is calculated.
Williford, Ralph E. (Kennewick, WA)
Comparison of pressure ransient response in intensely and sparsely fractured reservoirs
A comprehensive analytical model is presented to study the pressure transient behavior of a naturally fractured reservoir with a continuous matrix block size distribution. Geologically realistic probability density functions of matrix block size are used to represent reservoirs of varying fracture intensity and uniformity. Transient interporosity flow is assumed and interporosity skin is incorporated. Drawdown and interference pressure transient tests are investigated. The results show distinctions in the pressure response from intensely and sparsely fractured reservoirs in the absence of interporosity skin. Also, uniformly and nonuniformly fractured reservoirs exhibit distinct responses, irrespective of the degree of fracture intensity. The pressure response in a nonuniformly fractured reservoir with large block size variability, approaches a nonfractured (homogeneous) reservoir response. Type curves are developed to estimate matrix block size variability and the degree of fracture intensity from drawdown and interference well tests.
Johns, R.T.
Comparison of pressure transient response in intensely and sparsely fractured reservoirs
A comprehensive analytical model is presented to study the pressure transient behavior of a naturally fractured reservoir with a continuous matrix block size distribution. Geologically realistic probability density functions of matrix block size are used to represent reservoirs of varying fracture intensity and uniformity. Transient interporosity flow is assumed and interporosity skin is incorporated. Drawdown and interference pressure transient tests are investigated. The results show distinctions in the pressure response from intensely and sparsely fractured reservoirs in the absence of interporosity skin. Also, uniformly and nonuniformly fractured reservoirs exhibit distinct responses, irrespective of the degree of fracture intensity. The pressure response in a nonuniformly fractured reservoir with large block size variability, approaches a nonfractured (homogeneous) reservoir response. Type curves are developed to estimate matrix block size variability and the degree of fracture intensity from drawdown and interference well tests.
Johns, R.T.
Effects of non-condensible gases on fluid recovery in fractured geothermal reservoirs
Numerical simulations are performed in order to investigate the effects of noncondensible gases (CO/sub 2/) on fluid recovery and matrix depletion in fractured geothermal reservoirs. The model used is that of a well producing at a constant bottomhole pressure from a two-phase fractured reservoir. The results obtained have received a complex fracture-matrix interaction due to the thermodynamics of H/sub 2/O-CO/sub 2/ mixtures. Although the matrix initially contributes fluids (liquid and gas) to the fractures, later on, the flow directions reverse and the fractures backflow fluids into the matrix. The amount of backflow depends primarily upon the flowing gas saturation in the fractures; the lower the flowing gas saturation in the fractures the more backflow. It is shown that the recoverable fluid reserves depend strongly on the amount of CO/sub 2/ present in the reservoir system.
Bodvarsson, G.S.; Gaulke, S.
Hydraulic Fracture Optimization with a Pseudo-3D Model in Multi-layered Lithology
Hydraulic Fracturing is a technique to accelerate production and enhance ultimate recovery of oil and gas while fracture geometry is an important aspect in hydraulic fracturing design and optimization. Systematic design procedures are available based on the so-called two-dimensional models (2D) focus on the optimization of fracture length and width, assuming one can estimate a value for fracture height, while so-called pseudo three dimensional (p-3D) models suitable for multi-layered reservoirs aim to maximize well production by optimizing fracture geometry, including fracture height, half-length and width at the end of the stimulation treatment. The proposed p-3D approach to design integrates four parts: 1) containment layers discretization to allow for a range of plausible fracture heights, 2) the Unified Fracture Design (UFD) model to calculate the fracture half-length and width, 3) the PKN or KGD models to predict hydraulic fracture geometry and the associated net pressure and other treatment parameters, and, finally, 4) Linear Elastic Fracture Mechanics (LEFM) to calculate fracture height. The aim is to find convergence of fracture height and net pressure. Net pressure distribution plays an important role when the fracture is propagating in the reservoir. In multi-layered reservoirs, the net pressure of each layer varies as a result of different rock properties. This study considers the contributions of all layers to the stress intensity factor at the fracture tips to find the final equilibrium height defined by the condition where the fracture toughness equals the calculated stress intensity factor based on LEFM. Other than maximizing production, another obvious application of this research is to prevent the fracture from propagating into unintended layers (i.e. gas cap and/or aquifer). Therefore, this study can aid fracture design by pointing out: (1) Treating pressure needed to optimize fracture geometry, (2) The containment top and bottom layers of a multi-layered reservoir, (3) The upwards and downwards growth of the fracture tip from the crack center.
Yang, Mei
Proppant Fracture Conductivity with High Proppant Loading and High Closure Stress
Ultra-deepwater reservoirs are important unconventional reservoirs that hold the potential to produce billions of barrels of hydrocarbons, but also present major challenges. This type of reservoir is usually high pressure and high temperature (HPHT) and has a relatively high permeability. Hydraulic fracturing high permeability reservoirs are different from the hydraulic fracturing technology used in low permeability formations. The main purpose of hydraulic fracturing in low permeability reservoirs is to create a long, highly conductive path, whereas in high permeability formations hydraulic fracturing is used predominantly to bypass near wellbore formation damage, control sand production and reduce near wellbore pressure drop. Hydraulically fracturing these types of wells requires short fractures packed with high proppant concentrations. In addition, fracturing in high permeability reservoirs aims at achieving enough fracture length to increase productivity, especially when the viscosity of the reservoir fluid is high. In order to pump such a job and ensure long term productivity from the fracture, understanding the behavior of the fracture fluid and proppant is critical. A series of laboratory experiments have been conducted to study conductivity and fracture width with high proppant loading, high temperature and high pressure. Proppant was manually placed in the fracture and fracture fluid was pumped through the pack. Conductivity was measured by pumping oil to simulate reservoir conditions. Proppant performance and fracture fluids, which carry the proppant into the fracture, and their subsequent clean-up during production, were studied. High strength proppant is ideal for deep fracture stimulations and in this study different proppant loadings at different stresses were tested to see the impact of crushing and fracture width reduction on fracture conductivity. The preliminary test results indicated that oil at reservoir conditions improves clean-up of fracture fluid left in the proppant pack compared with using water at ambient temperature. Increasing the proppant concentration in the fracture showed higher conductivity values in some cases even at high closure stress. The increase in effective closure stress with high temperature resulted in a significant loss in conductivity. Additionally, the fracture width decreased with time and increased effective closure stress. Tests were also run to study the effect of cyclic loading which is expected to further decrease conductivity.
Rivers, Matthew Charles
Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Therefore, knowledge of the conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fractures are created in the reservoir using hydraulic fracturing. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result, it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have developed advanced poro-thermo-chemo-mechanical fracture models for rock fracture research in support of EGS design. The fracture propagation models are based on a regular displacement discontinuity formulation. The fracture propagation studies include modeling interaction of induced fractures. In addition to the fracture propagation studies, two-dimensional solution algorithms have been developed and used to estimate the impact of pro-thermo-chemical processes on fracture permeability and reservoir pressure. Fracture permeability variation is studied using a coupled thermo-chemical model with quartz reaction kinetics. The model is applied to study quartz precipitation/dissolution, as well as the variation in fracture aperture and pressure. Also, a three-dimensional model of injection/extraction has been developed to consider the impact poro- and thermoelastic stresses on fracture slip and injection pressure. These investigations shed light on the processes involved in the observed phenomenon of injection pressure variation (e.g., in Coso), and allow the assessment of the potential of thermal and chemical stimulation strategies.
Ahmad Ghassemi
A three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The overall objectives of the study were to: (1) evaluate the reservoir conditions for which fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. The evaluations of reservoir performance were made by a modern dual porosity simulator, TETRAD. This simulator treats both porosity and permeability as functions of pore pressure. The Austin Chalk in the Pearsall Field in of South Texas was selected as the prototype fractured reservoir for this work. During the first year, simulations of vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure change. Sensitivity runs indicated that the simulator was predicting the effects of critical reservoir parameters in a logical and consistent manner. The results confirmed that horizontal wells could increase both rate of oil recovery and total oil recovery from naturally fractured reservoirs. In the second year, the performance of the same vertical and horizontal wells was reevaluated with fracture permeability treated as a function of reservoir pressure. To investigate sensitivity to in situ stress, differing loading conditions were assumed. Simulated natural depletions confirm that pressure sensitive fractures degrade well performance. The severity of degradation worsens when the initial reservoir pressure approaches the average stress condition of the reservoir, such as occurs in over pressured reservoirs. Simulations with water injection indicate that degradation of permeability can be counteracted when reservoir pressure is maintained and oil recovery can be increased when reservoir properties are favorable.
Howrie, I.; Dauben, D.
Practical simulation of hierarchical brittle fracture
Science Conference Proceedings (OSTI)
A novel practical method for brittle fracture simulation is presented. Our fracture model is represented by a tree structure, and all elementary fracture pieces are hierarchically connected. Each node in a fracture tree has a glue table to define connections ... Keywords: fluid, fracture, rigid body
Seungtaik Oh; Seunghyup Shin; Hyeryeong Jun
Fracturing results in diatomaceous earth formations, South Belridge Field, California
Fracturing significantly increases light oil production rates at South Belridge making this an economically successful technique for exploitation of the Reef Ridge reservoir. No fracturing mechanics problems were encountered in any of the treatments. The loosely consolidated formations behaved mechanically much like brittle, elastic rocks. Net oil and gross production is typified by initial high rates and an early rapid decline. The major cause of this early rapid decline is the transient flow effect. This behavior is typical of low permeability oil and gas production. Fractures are vertical, as shown by gamma ray and temperature logs run following several treatments. The fractures grow slightly out of the perforated intervals (10 to 15 feet). Loss of fracture conductivity due to fines migration, scale deposition, and/or fracture healing (imbedment) is not a serious problem. Oil viscosity can vary as much as ten-fold. Some wells produce significant amounts of gas--100 to 200 MCFPD initially. The formation is primarily diatomaceous earth which is very fine particle size siliceous material composed of whole or fragmented diatom tests (skeletons). There is no evidence that clay swelling or dispersion is a problem. Field and laboratory data support this conclusion. Aqueous fracturing fluids were successfully used which confirmed laboratory tests on cores.
Strubhar, M.K.; Medin, W.L.
PrimeEnergy/DOE/GRI slant well
This report presents final results of the Sterling Boggs 1240 slant well. Objectives of the project were (1) to test the potential for improved recovery efficiency in a fractured Devonian Shale reservoir from a directionally drilled well, (2) to perform detailed tests of reservoir properties and completion methods, and (3) to provide technology to industry which may ultimately improve the economics of drilling in the Devonian Shale and thereby stimulate development of its resources.
Drimal, C.E.; Muncey, G.; Carden, R.
Science Conference Proceedings (OSTI)
This report summarizes the work carried out during the period of September 29, 2000 to January 15, 2004 under DOE Research Contract No. DE-FC26-00BC15308. High temperatures and reactive fluids in sedimentary basins dictate that interplay and feedback between mechanical and geochemical processes significantly influence evolving rock and fracture properties. Not only does diagenetic mineralization fill in once open fractures either partially or completely, it modifies the rock mechanics properties that can control the mechanical aperture of natural fractures. In this study, we have evolved an integrated methodology of fractured reservoir characterization and we have demonstrated how it can be incorporated into fluid flow simulation. The research encompassed a wide range of work from geological characterization methods to rock mechanics analysis to reservoir simulation. With regard to the characterization of mineral infilling of natural fractures, the strong interplay between diagenetic and mechanical processes is documented and shown to be of vital importance to the behavior of many types of fractured reservoirs. Although most recent literature emphasizes Earth stress orientation, cementation in fractures is likely a critically important control on porosity, fluid flow attributes, and even sensitivity to effective stress changes. The diagenetic processes of dissolution and partial cementation are key controls on the creation and distribution of open natural fractures within hydrocarbon reservoirs. The continuity of fracture-porosity is fundamental to how fractures conduct fluids. In this study, we have made a number of important discoveries regarding fundamental properties of fractures, in particular related to the prevalence of kinematically significant structures (crack-seal texture) within otherwise porous, opening-mode fractures, and the presence of an aperture size threshold below which fractures are completely filled and above which porosity is preserved. These observations can be linked to models of quartz cementation. Significant progress has been made as well in theoretical fracture mechanics and geomechanical modeling, allowing prediction of spatial distributions of fractures that mimic patterns observed in nature. Geomechanical modeling shows the spatial arrangement of opening mode fractures (joints and veins) is controlled by the subcritical fracture index of the material. In particular, we have been able to identify mechanisms that control the clustering of fractures in slightly deformed rocks. Fracture mechanics testing of a wide range of clastic rocks shows that the subcritical index is sensitive to diagenetic factors. We show geomechanical simulations of fracture aperture development can be linked to diagenetic models, modifying fracture porosity as fractures grow, and affect the dynamics of fracture propagation. Fluid flow simulation of representative fracture pattern realizations shows how integrated modeling can give new insight into permeability assessment in the subsurface. Using realistic, geomechanically generated fracture patterns, we propose a methodology for permeability estimation in nonpercolating networks.
Jon E. Olson; Larry W. Lake; Steve E. Laubach
Numerical modeling of boiling due to production in a fractured reservoir and its field application
Science Conference Proceedings (OSTI)
Numerical simulations were carried out to characterize the behaviors of fractured reservoirs under production which causes in-situ boiling. A radial flow model with a single production well, and a two-dimensional geothermal reservoir model with several production and injection wells were used to study the two-phase reservoir behavior. The behavior can be characterized mainly by the parameters such as the fracture spacing and matrix permeability. However, heterogeneous distribution of the steam saturation in the fracture and matrix regions brings about another complicated feature to problems of fractured two-phase reservoirs.
Yusaku Yano; Tsuneo Ishido
Wormhole formation in dissolving fractures
We investigate the dissolution of artificial fractures with three-dimensional, pore-scale numerical simulations. The fluid velocity in the fracture space was determined from a lattice-Boltzmann method, and a stochastic solver was used for the transport of dissolved species. Numerical simulations were used to study conditions under which long conduits (wormholes) form in an initially rough but spatially homogeneous fracture. The effects of flow rate, mineral dissolution rate and geometrical properties of the fracture were investigated, and the optimal conditions for wormhole formation determined.
Szymczak, P
Reservoir-scale fracture permeability in the Dixie Valley, Nevada, geothermal field
Science Conference Proceedings (OSTI)
Wellbore image data recorded in six wells penetrating a geothermal reservoir associated with an active normal fault at Dixie Valley, Nevada, were used in conjunction with hydrologic tests and in situ stress measurements to investigate the relationship between reservoir productivity and the contemporary in situ stress field. The analysis of data from wells drilled into productive and non-productive segments of the Stillwater fault zone indicates that fractures must be both optimally oriented and critically stressed to have high measured permeabilities. Fracture permeability in all wells is dominated by a relatively small number of fractures oriented parallel to the local trend of the Stillwater Fault. Fracture geometry may also play a significant role in reservoir productivity. The well-developed populations of low angle fractures present in wells drilled into the producing segment of the fault are not present in the zone where production is not commercially viable.
Barton, C.A.; Zoback, M.D. [Stanford Univ., CA (United States). Dept. of Geophysics; Hickman, S. [Geological Survey, Menlo Park, CA (United States); Morin, R. [Geological Survey, Denver, CO (United States); Benoit, D. [Oxbow Geothermal Corp., Reno, NV (United States)
Using Chemicals to Optimize Conformance Control in Fractured Reservoirs
This report describes work performed during the first year of the project, ''Using Chemicals to Optimize Conformance Control in Fractured Reservoirs.'' This research project has three objectives. The first objective is to develop a capability to predict and optimize the ability of gels to reduce permeability to water more than that to oil or gas. The second objective is to develop procedures for optimizing blocking agent placement in wells where hydraulic fractures cause channeling problems. The third objective is to develop procedures to optimize blocking agent placement in naturally fractured reservoirs. This research project consists of three tasks, each of which addresses one of the above objectives. Our work is directed at both injection wells and production wells and at vertical, horizontal, and highly deviated wells.
Seright, Randall S.; Liang, Jenn-Tai; Schrader, Richard; Hagstrom II, John; Liu, Jin; Wavrik, Kathryn
Geothermal reservoir well stimulation program. First-year progress report
The Geothermal Reservoir Well Stimulation Program (GRWSP) group planned and executed two field experiments at the Raft River KGRA during 1979. Well RRGP-4 was stimulated using a dendritic (Kiel) hydraulic fracture technique and Well RRGP-5 was stimulated using a conventional massive hydraulic fracture technique. Both experiments were technically successful; however, the post-stimulation productivity of the wells was disappointing. Even though the artificially induced fractures probably successfully connected with the natural fracture system, reservoir performance data suggest that productivity remained low due to the fundamentally limited flow capacity of the natural fractures in the affected region of the reservoir. Other accomplishments during the first year of the program may be summarized as follows: An assessment was made of current well stimulation technology upon which to base geothermal applications. Numerous reservoirs were evaluated as potential candidates for field experiments. A recommended list of candidates was developed which includes Raft River, East Mesa, Westmorland, Baca, Brawley, The Geysers and Roosevelt Hot Springs. Stimulation materials (fracture fluids, proppants, RA tracer chemicals, etc.) were screened for high temperature properties, and promising materials selected for further laboratory testing. Numerical models were developed to aid in predicting and evaluating stimulation experiments. (MHR)
Not Available
Science Conference Proceedings (OSTI)
The purpose of this work to investigate the ability to match observed pressure transient responses with a simulation model and the certainty of whether the simulation results are unique. To perform this work, INTERCOMP's Radial Single Well Gas Model (RADGAS) was used to establish a base case on which the uniqueness studies would be performed. Once the base cases were established, attempts were made to match their pressure transient responses, using RADGAS, with reservoir models having different characteristics; i.e., different fracture lengths, reservoir permeabilities, etc. The results of the study indicate that when certain parameters are accurately known through rock analysis and pressure studies, the simulations are unique, but that when a few key parameters are unknown and must be determined by matching the simulator response to the well's pressure transient behavior, uncertainty arises as to whether the solution is indeed unique. In addition to the uniqueness study, three additional exercises were performed to study the effects of fracture skin and wellbore storage, fracture geometry, and fracture fluid remaining in and around the fracture on the pressure transient responses and production forecasts of a well. 37 figures, 2 tables.
Bixel, H.C.; Christiansen, D.H.
Interferometric hydrofracture microseism localization using neighboring fracture
Hydraulic fracturing is the process of injecting high-pressure fluids into a reservoir to induce fractures and thus improve reservoir productivity. Microseismic event localization is used to locate created fractures. ...
Poliannikov, Oleg V.
A numerical model of hydro-thermo-mechanical coupling in a fractured rock mass
Coupled hydro-thermo-mechanical codes with the ability to model fractured materials are used for predicting groundwater flow behavior in fractured aquifers containing thermal sources. The potential applications of such a code include the analysis of groundwater behavior within a geothermal reservoir. The capability of modeling hydro-thermo systems with a dual porosity, fracture flow model has been previously developed in the finite element code, FEHM. FEHM has been modified to include stress coupling with the dual porosity feature. FEHM has been further developed to implicitly couple the dependence of fracture hydraulic conductivity on effective stress within two dimensional, saturated aquifers containing fracture systems. The cubic law for flow between parallel plates was used to model fracture permeability. The Bartin-Bandis relationship was used to determine the fracture aperture within the cubic law. The code used a Newton Raphson iteration to implicitly solve for six unknowns at each node. Results from a model of heat flow from a reservoir to the moving fluid in a single fracture compared well with analytic results. Results of a model showing the increase in fracture flow due to a single fracture opening under fluid pressure compared well with analytic results. A hot dry rock, geothermal reservoir was modeled with realistic time steps indicating that the modified FEHM code does successfully model coupled flow problems with no convergence problems.
Bower, K.M.
Characterizing Fractures in Geysers Geothermal Field by Micro-seismic Data,
Characterizing Fractures in Geysers Geothermal Field by Micro-seismic Data, Characterizing Fractures in Geysers Geothermal Field by Micro-seismic Data, Using Soft Computing, Fractals, and Shear Wave Anisotropy Geothermal Project Jump to: navigation, search Last modified on July 22, 2011. Project Title Characterizing Fractures in Geysers Geothermal Field by Micro-seismic Data, Using Soft Computing, Fractals, and Shear Wave Anisotropy Project Type / Topic 1 Recovery Act: Enhanced Geothermal Systems Component Research and Development/Analysis Project Type / Topic 2 Fracture Characterization Technologies Project Description The proposed program will focus on predicting characteristics of fractures and their orientation prior to drilling new wells. It will also focus on determining the location of the fractures, spacing and orientation during drilling, as well as characterizing open fractures after stimulation to help identify the location of fluid flow pathway within the EGS reservoir. These systems are created by passively injecting cold water, and stimulating the permeation of the injected water through existing fractures into hot wet and hot dry rocks by thermo-elastic cooling shrinkage. The stimulated, existing fractures thus enhance the permeability of the hot rock formations, hence enabling better circulation of water for the purpose of producing the geothermal resource. The main focus of the project will be on developing better understanding of the mechanisms for the stimulation of existing fractures, and to use the information for better exploitation of the high temperature geothermal resources located in the northwest portion of the Geysers field and similar fields.
The imbibition process of waterflooding in naturally fractured reservoirs
This thesis presents procedures to properly simulate naturally fractured reservoirs using dual-porosity models. The main objectives of this work are to: (1) determine if the spontaneous imbibition can be simulated using a two phase CMG simulator and validate it with laboratory experiments in the literature; (2) study the effect of countercurrent imbibition in field scale applications; and (3) develop procedures for using the dual-porosity to simulate fluid displacement in a naturally fractured reservoir. Reservoir simulation techniques, analytical solutions and numerical simulation for a two phase single and dual-porosity are used to achieve our objectives. Analysis of a single matrix block with an injector and a producer well connected by a single fracture is analyzed and compared with both two phase single and dual-porosity models. Procedures for obtaining reliable results when modeling a naturally fractured reservoir with a two phase dual-porosity model are presented and analyzed.
Huapaya Lopez, Christian A.
IDENTIFYING FRACTURES AND FLUID TYPES USING FLUID INCLUSION STRATIGRAPHY IDENTIFYING FRACTURES AND FLUID TYPES USING FLUID INCLUSION STRATIGRAPHY Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: IDENTIFYING FRACTURES AND FLUID TYPES USING FLUID INCLUSION STRATIGRAPHY Details Activities (1) Areas (1) Regions (0) Abstract: Fluid Inclusion Stratigraphy (FIS) is a method currently being developed for use in geothermal systems to identify fractures and fluid types. This paper is the third in a series of papers on the development of FIS. Fluid inclusion gas chemistry is analyzed and plotted on well log diagrams. The working hypothesis is that select gaseous species and species ratios indicate areas of groundwater and reservoir fluid flow and reservoir seals. Previously we showed that FIS analyses identify fluid types and
�Hanging� Pelvic Gallbladder Simulating Occult Hip Fracture Versus Appendicitis
Pelvic Gallbladder Simulating Occult Hip Fracture Versuspossibility of either an occult hip fracture or a subacute
Dolbec, Katherine W D; Higgins, George L; Jung, Michale W
Self-potential observations during hydraulic fracturing
and T. W. Keech (1977), Hydraulic fracture mapping usingpotential measurements during hydraulic fracturing of Bunterbetween electrical and hydraulic flow patterns from rock
Moore, J R; Glaser, Steven D
Some Fundamental Mechanisms of Hydraulic Fracturing .
??This dissertation focuses mainly on three topics: (1) mixed-mode branching and segmentation of hydraulic fractures in brittle materials, (2) hydraulic fracture propagation in particulate materials,� (more)
Wu, Ruiting
Shale Gas Development Challenges: Fracture Fluids | Department...
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NETL: Discrete Fracture Reservoir Simulation Software
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Discrete Fracture Reservoir Simulation FRACGENNFFLOW Shale Gas Flow Simulation Shale Gas Flow Simulation FRACGENNFFLOW, a fractured reservoir modeling software developed by the...
Chemical Signatures of and Precursors to Fractures Using Fluid Inclusion Stratigraphy
Science Conference Proceedings (OSTI)
Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Open or recently closed fractures would be more susceptible to enhancing the permeability of the system. Identifying dense fracture areas as well as large open fractures from small fracture systems will assist in fracture stimulation site selection. Geothermal systems are constantly generating fractures (Moore, Morrow et al. 1987), and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. These fluid inclusions are faithful records of pore fluid chemistry. Fluid inclusions trapped in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. This report presents the results of the project to determine fracture locations by the chemical signatures from gas analysis of fluid inclusions. With this project we hope to test our assumptions that gas chemistry can distinguish if the fractures are open and bearing production fluids or represent prior active fractures and whether there are chemical signs of open fracture systems in the wall rock above the fracture. Fluid Inclusion Stratigraphy (FIS) is a method developed for the geothermal industry which applies the mass quantification of fluid inclusion gas data from drill cuttings and applying known gas ratios and compositions to determine depth profiles of fluid barriers in a modern geothermal system (Dilley, 2009; Dilley et al., 2005; Norman et al., 2005). Identifying key gas signatures associated with fractures for isolating geothermal fluid production is the latest advancement in the application of FIS to geothermal systems (Dilley and Norman, 2005; Dilley and Norman, 2007). Our hypothesis is that peaks in FIS data are related to location of fractures. Previous work (DOE Grant DE-FG36-06GO16057) has indicated differences in the chemical signature of fluid inclusions between open and closed fractures as well as differences in the chemical signature of open fractures between geothermal systems. Our hypothesis is that open fracture systems can be identified by their FIS chemical signature; that there are differences based on the mineral assemblages and geology of the system; and that there are chemical precursors in the wall rock above open, large fractures. Specific goals for this project are: (1) To build on the preliminary results which indicate that there are differences in the FIS signatures between open and closed fractures by identifying which chemical species indicate open fractures in both active geothermal systems and in hot, dry rock; (2) To evaluate the FIS signatures based on the geology of the fields; (3) To evaluate the FIS signatures based on the mineral assemblages in the fracture; and (4) To determine if there are specific chemical signatures in the wall rock above open, large fractures. This method promises to lower the cost of geothermal energy production in several ways. Knowledge of productive fractures in the boreholes will allow engineers to optimize well production. This information can aid in well testing decisions, well completion strategies, and in resource calculations. It will assist in determining the areas for future fracture enhancement. This will develop into one of the techniques in the 'tool bag' for creating and managing Enhanced Geothermal Systems.
Lorie M. Dilley
Meshless animation of fracturing solids
Science Conference Proceedings (OSTI)
We present a new meshless animation framework for elastic and plastic materials that fracture. Central to our method is a highly dynamic surface and volume sampling method that supports arbitrary crack initiation, propagation, and termination, while ... Keywords: elasticity, fracture, meshless methods, physics-based animation, plasticity
Mark Pauly; Richard Keiser; Bart Adams; Philip Dutr�; Markus Gross; Leonidas J. Guibas
Characterization of Small Scale Heterogeneity for Prediction of Acid Fracture Performance
Recently developed models of the acid fracturing process have shown that the differential etching necessary to create lasting fracture conductivity is caused by the heterogeneous distributions of permeability and mineralogy along the fracture faces. To predict the conductivity that can be created by acid in a particular formation, the models require information about these formation properties. This research aims to quantify correlation lengths using a geostatistical description of small scale heterogeneity to ascertain the distribution of permeability and mineralogy in a carbonate formation. The correlation length parameters are a first step in being able to couple acid transport and rock dissolution models at reservoir scale with a model of fracture conductivity based on channels and roughness features caused by small scale heterogeneity. Geostatistical parameters of small scale heterogeneity affecting wells in the Hugoton Field are developed. Data leading to their derivation are obtained from a combination of well logs and cores. The permeability of slabbed core is measured to yield vertical correlation length. Well logs are used to estimate permeability via an empirical relationship between core plug permeability and well log data for calculation of horizontal correlation length. A fracture simulator computes the acid etched fracture width for known treatment conditions. The resulting geostatistical parameters and acid etched width are used to predict acid fracture performance for a well in the Hugoton Field. Application of new model conductivity correlations results in a unique prediction for the acid fracture case study that differs from the industry standard. Improvements in low cost stimulation treatments such as acid fracturing are the key to revitalizing production in mature carbonate reservoirs like the Hugoton Field. Planning and development of new wells in any carbonate formation necessarily must consider acid fracturing as a production stimulation technique. Reliable models that accurately predict acid fracture conductivity can be used to make an informed investment decision.
Beatty, Cassandra Vonne
Oil Recovery Enhancement from Fractured, Low Permeability Reservoirs. [Carbonated Water
DOE R&D Accomplishments (OSTI)
The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks. Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.
Poston, S. W.
Stimulation Technologies for Deep Well Completions
The Department of Energy (DOE) is sponsoring the Deep Trek Program targeted at improving the economics of drilling and completing deep gas wells. Under the DOE program, Pinnacle Technologies conducted a study to evaluate the stimulation of deep wells. The objective of the project was to review U.S. deep well drilling and stimulation activity, review rock mechanics and fracture growth in deep, high-pressure/temperature wells and evaluate stimulation technology in several key deep plays. This report documents results from this project.
Stephen Wolhart
Well Testing Techniques | Open Energy Information
Well Testing Techniques Well Testing Techniques Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Well Testing Techniques Details Activities (0) Areas (0) Regions (0) NEPA(17) Exploration Technique Information Exploration Group: Downhole Techniques Exploration Sub Group: Well Testing Techniques Parent Exploration Technique: Downhole Techniques Information Provided by Technique Lithology: Enable estimation of in-situ reservoir elastic parameters Stratigraphic/Structural: Fracture distribution, formation permeability, and ambient tectonic stresses Hydrological: provides information on permeability, location of permeable zones recharge rates, flow rates, fluid flow direction, hydrologic connections, storativity, reservoir pressures, fluid chemistry, and scaling.
well tests, multiphase flow, porous and fracturedin modeling multiphase flow in porous and fractured media,�description of multiphase flow through porous media: S w + S
Wu, Yu-Shu
Downhole tool sniffs out fractures
This article reports that a new tool has been designed and successfully tested that can designate which direction from a borehole a particular fracture is located. Albuquerque-based Sandia National Laboratories tested the new tool. The prototype was built by Southwest Research Institute of San Antonio. During field tests, the tool detected simulated fractures more than 30 ft away from a test borehole. It determines fracture direction by transmitting highly directional and powerful radar pulses in a known direction. The pulses last eight billionths of a second and their frequency spectrum range up to the VHF (very high frequency) band. Discontinuities in the rock interrupt and reflect radar signals so that a signal's return to the tool indicates the presence of fractures. The return signal's time delay translates into distance from the borehole. The transmitter and receiver rotate in place, permitting the tool to scan for fractures in all directions.
Not Available
Relative Permeability of Fractured Rock
Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.
Mark D. Habana
Hydraulic fracturing is a widely-used well completion technique for enhancing the recovery of gas and oil in low-permeability formations. Hydraulic fracturing consists of pumping fluids into a well under high pressure (1000--5000 psi) to wedge-open and extend a fracture into the producing formation. The fracture acts as a conduit for gas and oil to flow back to the well, significantly increasing communication with larger volumes of the producing formation. A considerable amount of research has been conducted on the use of acoustic (microseismic) emission to delineate fracture growth. The use of transient signals to map the location of discrete sites of emission along fractures has been the focus of most research on methods for delineating fractures. These methods depend upon timing the arrival of compressional (P) or shear (S) waves from discrete fracturing events at one or more clamped geophones in the treatment well or in adjacent monitoring wells. Using a propagation model, the arrival times are used to estimate the distance from each sensor to the fracturing event. Coherent processing methods appear to have sufficient resolution in the 75 to 200 Hz band to delineate the extent of fractures induced by hydraulic fracturing. The medium velocity structure must be known with a 10% accuracy or better and no major discontinuities should be undetected. For best results, the receiving array must be positioned directly opposite the perforations (same depths) at a horizontal range of 200 to 400 feet from the region to be imaged. Sources of acoustic emission may be detectable down to a single-sensor SNR of 0.25 or somewhat less. These conclusions are limited by the assumptions of this study: good coupling to the formation, acoustic propagation, and accurate knowledge of the velocity structure.
Harris, D.B.; Sherwood, R.J.; Jarpe, S.P.; Harben, P.E.
Foolproof completions for high rate production wells
Operators, especially those managing production from deepwater reservoirs, are striving to produce hydrocarbons at higher and higher rates without exposing the wells to completion failure risk. To avoid screen failures, recent studies have favored gravel pack (GP) and high rate water pack (HRWP) completions over high-permeability fracturing (HPF), known in the vernacular as a frac&pack (FP) for very high rate wells. While a properly designed GP completion may prevent sand production, it does not stop formation fines migration, and, over time, fines accumulation in the GP will lead to increasing completion skin. Although, and not always, the skin can be removed by acidizing, it is not practical to perform repeated acid treatments on deepwater wells, particularly those with subsea wellheads, and the alternative has been to subject the completion to increasingly high drawdown, accepting a high skin effect. A far better solution is to use a HPF completion. Of course the execution of a successful HPF is not a trivial exercise, and frequently, there is a steep learning curve for such a practice. This work explains the importance to HPF completions of the well trajectory through the interval to be hydraulically fractured, for production, not execution, reasons. A new model quantifies the effect of the well inclination on the connectivity between the fracture and the well via perforations. Guidelines based on the maximum target production rate, including forecasts of multiphase flow, are provided to size the HPF completion to avoid common completion failures that may result from high fluid rate and/or fines movement. Skin model will be developed for both vertical and deviated wells. Once the HPF is properly designed and executed, the operators should end up with a long term low skin good completion quality well. The well will be safely produced at the maximum flow rates, with no need for well surveillance and monitoring.
Tosic, Slavko
Portable water filtration system for oil well fractionation
Science Conference Proceedings (OSTI)
The invention comprises a portable, multi-stage filtration system utilized in filtering water for an oil and gas stimulation process commonly known as fracking. Three stages are used, the first being a straining operation reducing the size of particulate matter in the water to about three-eighths of an inch. The second stage is a centrifugal separator, reducing the particle size to about 50 microns. The final stage utilizes a cartridge-type filter giving a final particle size in the water of about 5 microns. In this manner, water which is injected into the well head during the fracking process and which is obtained from readily available sources such as ponds, streams and the like is relatively free of particulate matter which can foul the fracking process. The invention, by virtue of being mounted on a trailer, is portable and thus can be easily moved from site to site. Water flow rates obtained using the invention are between 250 and 300 gallons per minute, sufficient for processing a small to medium sized well.
Seibert, D. L.
In geothermal reservoirs and unconventional gas reservoirs with very low matrix permeability, fractures are the main routes of fluid flow and heat transport, so the fracture permeability change is important. In fact, reservoir development under this circumstance relies on generation and stimulation of a fracture network. This thesis presents numerical simulation of the response of a fractured rock to injection and extraction considering the role of poro-thermoelasticity and joint deformation. Fluid flow and heat transport in the fracture are treated using a finite difference method while the fracture and rock matrix deformation are determined using the displacement discontinuity method (DDM). The fractures response to fluid injection and extraction is affected both by the induced stresses as well as by the initial far-field stress. The latter is accounted for using the non-equilibrium condition, i.e., relaxing the assumption that the rock joints are in equilibrium with the in-situ stress state. The fully coupled DDM simulation has been used to carry out several case studies to model the fracture response under different injection/extractions, in-situ stresses, joint geometries and properties, for both equilibrium and non-equilibrium conditions. The following observations are made: i) Fluid injection increases the pressure causing the joint to open. For non-isothermal injection, cooling increases the fracture aperture drastically by inducing tensile stresses. Higher fracture aperture means higher conductivity. ii) In a single fracture under constant anisotropic in-situ stress (non-equilibrium condition), permanent shear slip is encountered on all fracture segments when the shear strength is overcome by shear stress in response to fluid injection. With cooling operation, the fracture segments in the vicinity of the injection point are opened due to cooling-induced tensile stress and injection pressure, and all the fracture segments experience slip. iii) Fluid pressure in fractures increases in response to compression. The fluid compressibility and joint stiffness play a role. iv) When there are injection and extraction in fractured reservoirs, the cooler fluid flows through the fracture channels from the injection point to extraction well extracting heat from the warmer reservoir matrix. As the matrix cools, the resulting thermal stress increases the fracture apertures and thus increases the fracture conductivity. v) Injection decreases the amount of effective stress due to pressure increase in fracture and matrix near a well. In contrast, extraction increases the amount of effective stress due to pressure drop in fracture and matrix.
Lee, Byungtark
Single fracture aperture patterns: Characterization by slit-island fractal analysis
Science Conference Proceedings (OSTI)
Single fracture measurements are difficult to obtain, but they are the only means we have to observe and study natural fracture morphology. The character of the fracture openings (apertures) is often one of the primary factors controlling fluid flow in the fracture. In particular, the shape, distribution, and connectivity of contact areas and flow channels can affect the relative permeability of wetting and non-wetting fluid phases in unsaturated systems. In this paper we use three methods of fractal analysis (the slit-island, the divider, and the variogram) as well as statistical and geostatistical analysis to characterize the geometry of measured fracture apertures obtained from two different fractured rock specimens from the field. One of these is a granitic fracture (crack) of homogeneous lithology and no displacement, the other is a fracture (fault) obtained from a highly altered fault zone, containing striations and slickensides. We discuss the fractal and geostatistical analysis of these two fractures in the context of what information is most helpful for making predictions about fluid flow in single fractures.
Cox, B.L.; Wang, J.S.Y.
Finding Large Aperture Fractures in Geothermal Resource Areas Using a
Finding Large Aperture Fractures in Geothermal Resource Areas Using a Finding Large Aperture Fractures in Geothermal Resource Areas Using a Three-Component Long-Offset Surface Seismic Survey Geothermal Project Jump to: navigation, search Last modified on July 22, 2011. Project Title Finding Large Aperture Fractures in Geothermal Resource Areas Using a Three-Component Long-Offset Surface Seismic Survey Project Type / Topic 1 Recovery Act: Geothermal Technologies Program Project Type / Topic 2 Validation of Innovative Exploration Technologies Project Description Because fractures and faults with sub-commercial permeability can propagate hot fluid and hydrothermal alteration throughout a geothermal reservoir, potential field geophysical methods including resistivity, gravity, heatflow and magnetics cannot distinguish between low-permeability fractures and LAF's (Large Aperature Fractures). USG will develop and test the combination of three-component,long-offset seismic surveying, permanent scatter synthetic aperture radar interferometry (PSInSAR) and structural kinematic analysis as an integrated method for locating and 3-D mapping of LAF's in shallow to intermediate depth (600-4000 feet) geothermal systems. This project is designed to test the methodology on known occurrences of LAF's and then apply the technology to expand an existing production field and find a new production field in a separate but related resource area. A full diameter production well will be drilled into each of the two lease blocks covered by the geophysical exploration program.
A method of inducing a fracture system and multiple cavities in earthen formations is described. A first explosive, preferably nuclear, is buried at a sufficient depth so that its subsequent detonation is fully contained within the earth. Thereafter a second explosive, also preferably nuclear, is buried a predetermined distance from the situs of the first explosive. After detonation of the first explosive, time is allowed to elapse during which the cavity formed by the first explosive collapses to form a rubblized chimney. Thereafter, the second explosive is detonated to create a second chimney parallel to that of the first explosive together with a zone of enhanced permeability between the first and second. (10 claims)
Boardman, C.R.; Knutson, C.F.
Fracturing Fluid Characterization Facility
NLE Websites -- All DOE Office Websites (Extended Search)
Documentation Page Documentation Page 1. Report No. DE - FC 21 - 92MC29077 2. 3. Recipient's Accession No. 5. Report Date August 31, 2000 4. Title and Subtitle Fracturing Fluid Characterization Facility 6. 7. Author(s) The University of Oklahoma 8. Performing Organization Rept. No. 10. Project/Task/Work Unit No. 9. Performing Organization Name and Address The University of Oklahoma Sarkeys Energy Center T301 100 E Boyd St Norman, OK 73019 11. Contract (C) or Grant (G) No. DOE:DE FC21 92 MC29077 13. Type of Report & Period Covered Final Report 09 30 92 - 03 31 00 12. Sponsoring Organization Name and Address US Dept of Energy - FETL 3610 Collins Ferry Road Morgantown, WV 26505 14. 15. Supplementary Notes Several technical papers were prepared and presented at various Society of Petroleum Engineers Conferences and US
Review of the geothermal reservoir well stimulation program
The overall program and the four experimental fracture stimulation treatments completed to date are described. The GRWSP is organized into two phases. Phase I consists of studies (literature and theoretical), laboratory investigations, and numerical work. Phase II will include the planning, execution and evaluation of six well stimulation treatments which utilize the technology developed in Phase I. Two stimulation experiments were performed at the Raft River, Idaho, Known Geothermal Resource Area (KGRA) in late-1979. This is a naturally fractured, hard rock reservoir with a relatively low geothermal resource temperature (300/sup 0/F). A conventional planar hydraulic fracture job was performed in Well RRGP-5 and a Kiel dendritic (or reverse flow) technique was utilized in Well RRGP-4. In mid-1980, two stimulation experiments were performed at the East Mesa, California, KGRA. The stimulation of Well 58-30 provided the first geothermal well fracturing experience in a moderate temperature (350/sup 0/F/sup +/) reservoir with matrix type rock properties. The two treatments consisted of a conventional hydraulic fracture of a deep, low permeability zone and a minifrac Kiel treatment of a shallow, high permeability zone in the same well. The stimulation experiment results to date were evaluated using short-term production tests, conventional pressure transient analysis, interference pressure data, chemical and radioactive tracers, borehole acoustic televiewer surveys, and numerical models.
Campbell, D.A.; Hanold, R.J.; Sinclair, A.R.; Vetter, O.J.
Science Conference Proceedings (OSTI)
The primary objective of this project is to provide laboratory data that is pertinent to designing hydraulic fracturing treatments for coalbed methane. Coal fluid interactions studies, fracture conductivity, fluid leak-off through cleats, rheology, and proppant transport are designed to respresent Black Warrior and San Juan treatments. A second objective is to apply the information learned in laboratory testing to actual hydraulic fracturing treatments in order to improve results. A final objective is to review methods currently used to catalog well performance following hydraulic fracturing for the purpose of placing the data in a useable database that can be accessed by users to determine the success of various treatment scenarios.
Penny, G.S.; Conway, M.W.
Modelling cleavage fracture of bainitic steels
Science Conference Proceedings (OSTI)
The origin of brittle fracture of polycrystalline metals failing by cleavage is most frequently associated to slip-induced cracking of some non-metallic brittle particle or inclusion (a carbide in ferritic steels). When the size of the particles is smaller than the grain size of the metallic matrix, the nucleating event of a macroscopic failure results from the successive occurrence of three simple events: slip-induced cleavage of a particle, transmission of the microcrack to the neighboring grain across the particle/matrix interface and propagation of the grain-size microcrack to the neighboring grains across the grain boundary. On the basis of this scheme, a statistical weakest link'' fracture model has been developed which takes into account the presence of two independent distributions of structural elements (isolated particles and matrix grains) with two barriers for cleavage propagation (the particle/matrix interfaces and the grain boundaries), characterized by a crack arrest capability well over the crack propagation resistance of the cleavage planes of the crystalline lattices of the two planes. An application of the model to the prediction of the fracture stress and the critical stress intensity factor as a function of the temperature of a bainitic steel is presented.
Martin-Meizoso, A.; Ocana-Arizcorreta, I.; Gil-Sevillano, J.; Fuentes-Perez, M. (Univ. de Navarra, San Sebastian (Spain). Escuela Superior de Ingenieros Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa, San Sebastian (Spain))
A Review of the Geothermal Reservoir Well Stimulation Program
Republic Geothermal, Inc., and its subcontractors have planned and executed four experimental fracture stimulation treatments under the Department of Energy-funded Geothermal Reservoir Well Stimulation Program (GRWSP). The 2-year program, begun in February 1979, is Ultimately to include six full-scale field hydraulic and chemical stimulation experiments in geothermal wells. This paper describes the overall program and the four treatments completed to date. The GRWSP is organized into two phases. Phase I consists of literature and theoretical studies, laboratory investigations, and numerical work. The main purpose of this work is to establish the technological bases for geothermal well stimulation design. Phase I1 will include the planning, execution, and evaluation of six well stimulation treatments which utilize the technology developed in Phase I. Two stimulation experiments were performed at the Raft River, Idaho, known geothermal resource area (KGRA) in late 1979. This is a naturally fractured, hard rock reservoir with a relatively low geothermal resource temperature 149 C {+-} (300 F{+-}). A conventional planar hydraulic fracture job was performed in Well RRGP-5 and a ''Kiel'' dendritic, or reverse flow, technique was utilized in Well RRGP-4. In mid-1980, two stimulation experiments were performed at the East Mesa, California, KGRA. The stimulation of Well 58-30 provided the first geothermal well fracturing experience in a moderate temperature, 177 C {+-} (350 F{+-}), reservoir with matrix-type rock properties. The two treatments consisted of a conventional hydraulic fracture of a deep, low-permeability zone and a mini-frac ''Kiel'' treatment of a shallow, high-permeability zone in the same well. The stimulation experiment results to date were evaluated using short-term production tests, conventional pressure transient analysis, interference pressure data, chemical and radioactive tracers, borehole acoustic televiewer surveys and numerical models. This combination of evaluation techniques yielded an interpretation of fracture geometry and productivity enhancement. However, the evaluation of artificially induced fractures in naturally fractured formations was found to lead to possibly non-unique solutions. In all the field experiments, artificial fractures were created and well productivity was increased. A discussion of the prestimulation and poststimulation data and their evaluation are provided for each experiment in this report.
Campbell, D. A.; Hanold, R. J.; Sinclair, A. R.; Vetter, O. J.
National Nuclear Security Administration (NNSA)
SPALL FRACTURE AND SPALL FRACTURE AND SPALL FRACTURE AND SPALL FRACTURE AND COMPACTION COMPACTION IN NATURAL URANIUM IN NATURAL URANIUM UNDER SHOCK UNDER SHOCK - - WAVE LOADING WAVE LOADING O.A. O.A. Tyupanova Tyupanova , S.S. , S.S. Nadezhin Nadezhin , A.N. , A.N. Malyshev Malyshev , , O.N. O.N. Ignatova Ignatova , V.I. , V.I. Skokov Skokov , V.N. , V.N. Knyazev Knyazev , , V.A. V.A. Raevsky Raevsky , N.A. , N.A. Yukina Yukina Russian Federal Nuclear Center Russian Federal Nuclear Center - - VNIIEF, VNIIEF, Sarov Sarov , Russia , Russia Introduction Introduction Nucleation and growth of defects inside a solid under pulse tensile stresses signify a necessity to consider it as a damaged medium. A certain volume of experimental data, obtained in correct tests, which are sensitive to a characteristic under study, is necessary
A new method for determining dominant fluid flow paths during hydraulic fracturing
Although hydraulic fracturing is a method that has been applied for many years to increase fracture permeability of reservoirs, there is no direct way other than drilling additional boreholes to determine where the injected fluid has gone and thus what direction fractures have propagated. Information about fluid flow paths is important for designing subsequent fracturing operations for nearby wells or for choosing a trajectory for a second well to drill through the fracture system, and thus create a hot dry rock geothermal energy reservoir. A method has been developed for determining the orientations and locations of fractures along which fluid flows during hydraulic fracturing. The method is based on accurate determination of the locations of microseismic events, or microearthquakes, that accompany the hydraulic injection. The method has been applied to data collected during a massive hydraulic fracturing experiment carried out as part of the hot dry rock project. Planes with five different orientations were found in the data. The planes determined using the method intersect the injection borehole and a second, nearby borehole, in regions where other data indicate that fractures are present.
Fehler, M.
Evaluation of fracturing results in deviated wellbores through on-site measurements
Four adjacent oil wells in the Kuparuk River oil field, with deviated angles of 6{sup 0}5', 24{sup 0}6', 27{sup 0} and 36{sup 0}7' from the vertical at the perforations, were analyzed with prefracturing tests. The total fluid volume for these tests varied from 645 to 840 bbl(103 to 134 m/sup 3/) of either clean lease oil or water-based fracturing fluid at low to intermediate rates (up to 15bbl/min(2.4m/sup 3/)). These wells were subsequently fractured with proppant-laden fluid. A series of instantaneous shut-in pressures (ISIO's) was obtained for each well. ISIP's and fracturing pressures decreased with time in two of the four wells with a relatively high friction pressure at the end of the pumping. A radially propagating fracture from a point source of pressure explains this decreasing pressure with time. The elasticity theory predicts that a fracture in a deviated, cased wellbore should intersect the wellbore at one location. Only when the deviated wellbore azimuth is near that of the fracture orientation does the fracture sweep the entire perforated zone. This observation of the fracture orientation relative to the wellbore azimuth based on the pressure analysis is enhanced further by postfracture temperature surveys. It appears that only a relatively small volume of proppant could be displaced in a deviated wellbore. The degree of deviation, however, did not appear to be a major concern in the treatment of size.
Kim, C.M. (Halliburton Services, Duncan, OK (USA)); Champion, J.H. (Arco Alaska Inc. (US)); Cooper, G.D. (Guydon Software Services (US))
Correlations to predict frictional pressure loss of hydraulic-fracturing slurry in coiled tubing
Science Conference Proceedings (OSTI)
Compared with conventional-tubing fracturing, coiled-tubing (CT) fracturing has several advantages. CT fracturing has become an effective stimulation technique for multizone oil and gas wells. It is also an attractive production-enhancement method for multiseam coalbed-methane wells, and wells with bypassed zones. The excessive frictional pressure loss through CT has been a concern in fracturing. The small diameter of the string limits the cross-sectional area open to flow. Furthermore, the tubing curvature causes secondary flow and results in extra flow resistance. This increased frictional pressure loss results in high surface pumping pressure. The maximum possible pump rate and sand concentration, therefore, have to be reduced. To design a CT fracturing job properly, it is essential to predict the frictional pressure loss through the tubing accurately. This paper presents correlations for the prediction of frictional pressure loss of fracturing slurries in straight tubing and CT. They are developed on the basis of full-scale slurry-flow tests with 11/2-in. CT and slurries prepared with 35 lbm/1,000 gal of guar gel. The extensive experiments were conducted at the full-scale CT-flow test facility. The proposed correlations have been verified with the experimental data and actual field CT-fracturing data. Case studies of wells recently fractured are provided to demonstrate the application of the correlations. The correlations will be useful to the CT engineers in their hydraulics design calculations.
Shah, S.; Zhoi, Y.X.; Bailey, M.; Hernandez, J. [University of Oklahoma, Norman, OK (United States)
Modeling interfacial fracture in Sierra.
This report summarizes computational efforts to model interfacial fracture using cohesive zone models in the SIERRA/SolidMechanics (SIERRA/SM) finite element code. Cohesive surface elements were used to model crack initiation and propagation along predefined paths. Mesh convergence was observed with SIERRA/SM for numerous geometries. As the funding for this project came from the Advanced Simulation and Computing Verification and Validation (ASC V&V) focus area, considerable effort was spent performing verification and validation. Code verification was performed to compare code predictions to analytical solutions for simple three-element simulations as well as a higher-fidelity simulation of a double-cantilever beam. Parameter identification was conducted with Dakota using experimental results on asymmetric double-cantilever beam (ADCB) and end-notched-flexure (ENF) experiments conducted under Campaign-6 funding. Discretization convergence studies were also performed with respect to mesh size and time step and an optimization study was completed for mode II delamination using the ENF geometry. Throughout this verification process, numerous SIERRA/SM bugs were found and reported, all of which have been fixed, leading to over a 10-fold increase in convergence rates. Finally, mixed-mode flexure experiments were performed for validation. One of the unexplained issues encountered was material property variability for ostensibly the same composite material. Since the variability is not fully understood, it is difficult to accurately assess uncertainty when performing predictions.
Brown, Arthur A.; Ohashi, Yuki; Lu, Wei-Yang; Nelson, Stacy A. C.; Foulk, James W.,; Reedy, Earl David,; Austin, Kevin N.; Margolis, Stephen B.
Understanding and quantifying multi-phase flow in fractures is important for mathematical and numerical simulation of geothermal reservoirs, nuclear waste repositories, and petroleum reservoirs. While the cubic law for single-phase flow has been well established for parallel-plate fractures theoretically and experimentally, no reliable measurements of multi-phase flow in fractures have been reported. This work reports the design and fabrication of an apparatus for visualization of two-phase flow and for measurement of gas-liquid relative permeability in realistic rough-walled rock fractures. A transparent replica of a natural rock fracture from a core specimen is fabricated by molding and casting in clear epoxy. Simultaneous flow of gas and liquid with control of capillary pressure at inlet and outlet is achieved with the Hassler sandwich'' design: liquid is injected to the fracture through a porous block, while gas is injected directly to the edge of the fracture through channels in the porous block. A similar arrangement maintains capillary separation of the two phases at the outlet. Pressure drops in each phase across the fracture, and capillary pressures at the inlet and outlet, are controlled by means of pumps and needle valves, and are measured by differential and absolute pressure transducers. The clear epoxy cast of the natural fracture preserves the geometry of the fracture and permits visual observation of phase distributions. The fracture aperture distribution can be estimated by filling the fracture with a dyed liquid, and making pointwise measurements of the intensity of transmitted light.
Persoff, P.; Pruess, K.; Myer, L.
Numerical Modeling of Fractured Shale-Gas and Tight-Gas Reservoirs Using Unstructured Grids
Various models featuring horizontal wells with multiple induced fractures have been proposed to characterize flow behavior over time in tight gas and shale gas systems. Currently, there is little consensus regarding the effects of non-ideal fracture geometries and coupled primary-secondary fracture interactions on reservoir performance in these unconventional gas reservoirs. This thesis provides a grid construction tool to generate high-resolution unstructured meshes using Voronoi grids, which provides the flexibility required to accurately represent complex geologic domains and fractures in three dimensions. Using these Voronoi grids, the interaction between propped hydraulic fractures and secondary "stress-release" fractures were evaluated. Additionally, various primary fracture configurations were examined, where the fractures may be non-planar or non-orthogonal. For this study, a numerical model was developed to assess the potential performance of tight gas and shale gas reservoirs. These simulations utilized up to a half-million grid-blocks and consider a period of up to 3,000 years in some cases. The aim is to provide very high-definition reference numerical solutions that will exhibit virtually all flow regimes we can expect in these unconventional gas reservoirs. The simulation results are analyzed to identify production signatures and flow regimes using diagnostic plots, and these interpretations are confirmed using pressure maps where useful. The coupled primary-secondary fracture systems with the largest fracture surface areas are shown to give the highest production in the traditional "linear flow" regime (which occurs for very high conductivity vertical fracture cases). The non-ideal hydraulic fracture geometries are shown to yield progressively lower production as the angularity of these fractures increases. Hence, to design optimum fracture completions, we should endeavor to keep the fractures as orthogonal to the horizontal well as possible. This work expands the current understanding of flow behavior in fractured tight-gas and shale-gas systems and may be used to optimize fracture and completion design, to validate analytical models and to facilitate more accurate reserves estimation.
Olorode, Olufemi Morounfopefoluwa
Reinjection Model Studies in Fractured and Homogeneous Geothermal Systems
Reinjection of geothermal waste waters has become an important topic of interest for industry as well as for research. The environmental concerns due to chemical composition of geothermal waste waters had urged the industry to dispose it underground. In several field applications no interference due to thermal front breakthrough was observed on the other hand some cases are reported where reinjection had caused severe declines in energy production due to unexpected breakthrough of injected water. Several analytical and numerical studies are available where the effect of fractures on the movement of thermal front are discussed. It was shown that when the conduction heat transfer from matrix to fracture dominates, retardation of the thermal front movement will be observed. Bodvarsson and Pruess considered the above problem in a five-spot well pattern. They observed as the amount of fluid injected reaches the amount produced, the long-term energy output of the system increases. Pruess in his study compares the behavior of porous medium and fractured medium in terms of pressure decline due to production. Temperature and pressure profiles are presented between an injector and a producer where heating of the injected water in porous medium and in fractured medium with small fracture spacing was high compared to a larger fracture spacing. Such observations from the numerical studies were checked against some limited field examples. However understanding of the injection effects in fractured reservoirs is limited. This work presents the results of laboratory experiments where effects of reinjection on temperature and pressure behavior of a porous medium and a fractured medium were investigated. The porous medium was a crushed limestone pack, with 10 mm average particle size, packed in a 3-D box model where injection and production ports are located on the diagonal ends simulating a five-spot pattern. The fractured medium was made from uniformly cut marble blocks packed in such a way to permit uniform fracture geometry. The pressure and temperature response of both models are analyzed as a function of (1) depth of injection and production; and (2) injection rate where 20 C injection water is injected into 110 C reservoir.
Okandan, E.; Hosca, H.
Design and Implementation of Energized Fracture Treatment in Tight Gas Sands
Hydraulic fracturing is essential for producing gas and oil at an economic rate from low permeability sands. Most fracturing treatments use water and polymers with a gelling agent as a fracturing fluid. The water is held in the small pore spaces by capillary pressure and is not recovered when drawdown pressures are low. The un-recovered water leaves a water saturated zone around the fracture face that stops the flow of gas into the fracture. This is a particularly acute problem in low permeability formations where capillary pressures are high. Depletion (lower reservoir pressures) causes a limitation on the drawdown pressure that can be applied. A hydraulic fracturing process can be energized by the addition of a compressible, sometimes soluble, gas phase into the treatment fluid. When the well is produced, the energized fluid expands and gas comes out of solution. Energizing the fluid creates high gas saturation in the invaded zone, thereby facilitating gas flowback. A new compositional hydraulic fracturing model has been created (EFRAC). This is the first model to include changes in composition, temperature, and phase behavior of the fluid inside the fracture. An equation of state is used to evaluate the phase behavior of the fluid. These compositional effects are coupled with the fluid rheology, proppant transport, and mechanics of fracture growth to create a general model for fracture creation when energized fluids are used. In addition to the fracture propagation model, we have also introduced another new model for hydraulically fractured well productivity. This is the first and only model that takes into account both finite fracture conductivity and damage in the invaded zone in a simple analytical way. EFRAC was successfully used to simulate several fracture treatments in a gas field in South Texas. Based on production estimates, energized fluids may be required when drawdown pressures are smaller than the capillary forces in the formation. For this field, the minimum CO{sub 2} gas quality (volume % of gas) recommended is 30% for moderate differences between fracture and reservoir pressures (2900 psi reservoir, 5300 psi fracture). The minimum quality is reduced to 20% when the difference between pressures is larger, resulting in additional gas expansion in the invaded zone. Inlet fluid temperature, flow rate, and base viscosity did not have a large impact on fracture production. Finally, every stage of the fracturing treatment should be energized with a gas component to ensure high gas saturation in the invaded zone. A second, more general, sensitivity study was conducted. Simulations show that CO{sub 2} outperforms N{sub 2} as a fluid component because it has higher solubility in water at fracturing temperatures and pressures. In fact, all gas components with higher solubility in water will increase the fluid's ability to reduce damage in the invaded zone. Adding methanol to the fracturing solution can increase the solubility of CO{sub 2}. N{sub 2} should only be used if the gas leaks-off either during the creation of the fracture or during closure, resulting in gas going into the invaded zone. Experimental data is needed to determine if the gas phase leaks-off during the creation of the fracture. Simulations show that the bubbles in a fluid traveling across the face of a porous medium are not likely to attach to the surface of the rock, the filter cake, or penetrate far into the porous medium. In summary, this research has created the first compositional fracturing simulator, a useful tool to aid in energized fracture design. We have made several important and original conclusions about the best practices when using energized fluids in tight gas sands. The models and tools presented here may be used in the future to predict behavior of any multi-phase or multi-component fracturing fluid system.
Mukul Sharma; Kyle Friehauf
Reservoir-Scale Fracture Permeability in the Dixie Valley, Nevada,
Reservoir-Scale Fracture Permeability in the Dixie Valley, Nevada, Reservoir-Scale Fracture Permeability in the Dixie Valley, Nevada, Geothermal Field Jump to: navigation, search OpenEI Reference LibraryAdd to library Conference Paper: Reservoir-Scale Fracture Permeability in the Dixie Valley, Nevada, Geothermal Field Abstract Borehole televiewer, temperature, and flowmeter datarecorded in six wells penetrating a geothermalreservoir associated with the Stillwater fault zone inDixie Valley, Nevada, were used to investigate therelationship between reservoir permeability and thecontemporary in situ stress field. Data from wellsdrilled into productive and nonproductive segments ofthe Stillwater fault zone indicate that permeability inall wells is dominated by a relatively small number offractures striking parallel to the local trend of
Temporary Sealing of Fractures | Open Energy Information
Temporary Sealing of Fractures Temporary Sealing of Fractures Jump to: navigation, search Contents 1 Geothermal Lab Call Projects for Temporary Sealing of Fractures 2 Geothermal ARRA Funded Projects for Temporary Sealing of Fractures Geothermal Lab Call Projects for Temporary Sealing of Fractures Loading map... {"format":"googlemaps3","type":"ROADMAP","types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"limit":200,"offset":0,"link":"all","sort":[""],"order":[],"headers":"show","mainlabel":"","intro":"","outro":"","searchlabel":"\u2026
Fracture of aluminum naval structures
Structural catastrophic failure of naval vessels due to extreme loads such as underwater or air explosion, high velocity impact (torpedoes), or hydrodynamic loads (high speed vessels) is primarily caused by fracture. ...
Galanis, Konstantinos, 1970-
Ductile Fracture Handbook: Volume 2
Science Conference Proceedings (OSTI)
The three-volume Ductile Fracture Handbook provides the structural analyst with computational methods for evaluating the integrity of flawed structures that are fabricated from ductile materials or have loads that may produce significant plasticity, specifically easy-to-use fracture mechanics solutions for a wide range of problems dealing with cylinders subjected to several types of elastic-plastic loading. Volume 2 presents new solutions and significant expansion of previous solutions, typically in the ...
Ductile Fracture Handbook: Volume 3
Science Conference Proceedings (OSTI)
The three-volume Ductile Fracture Handbook provides the structural analyst with computational methods for evaluating the integrity of flawed structures that are fabricated from ductile materials or have loads that may produce significant plasticity, specifically easy-to-use fracture mechanics solutions for a wide range of problems dealing with cylinders subjected to several types of elastic-plastic loading. Volume 3 presents solutions for axial part-throughwall cracks, cracks in elbows, tees, and nozzles...
Geothermal Reservoir Well Stimulation Program: technology transfer
The following are included: review of available data from previous fracturing stimulation operations, stimulation process variables, fracturing fluid design, hydraulic fracture design, stimulation case histories, and selected bibliography. (MHR)
Not Available
Determination of the effect of formation water on fracture-fluid cleanup
Understanding hydraulic-fracture cleanup is essential for improving well stimulation. Residual gel damages fracture conductivity, shortens effective fracture half-length, and limits well productivity. The drive to develop fluids, additives, and procedures that minimize this damage continues to be a dominant theme in fracture-fluid-development programs. Fracture cleanup is a complex problem, and many parameters (e.g., fluid system, job design, flowback procedure, and reservoir conditions) can influence polymer and fluid recovery efficiencies. Often, specific products and methods that work well in one reservoir have little effect in another. Systematic analysis of fluid and polymer returns after a treatment is completed is the only way to quantify fracture cleanup. This is referred to as flowback analysis. This paper discusses a flowback-analysis field study on large hydraulic-fracturing treatments in the Taylor zone of the Cotton Valley formation in east Texas. This is a low-permeability (approximately 0.01 md) tight gas formation. It is a heterogeneous zone with layers of productive sandstone interspersed with relatively impermeable layers of shale. A typical well in this field initially produces approximately 0.75 to 1.3 MMcf/D gas and 35 to 40 bbl of water/MMcf of gas. The returns from 10 wells in this field were analyzed thoroughly.
The primary objective of our current research is to develop a computational test bed for evaluating borehole techniques to enhance fluid flow and heat transfer in enhanced geothermal systems (EGS). Simulating processes resulting in hydraulic fracturing and/or the remobilization of existing fractures, especially the interaction between propagating fractures and existing fractures, represents a critical goal of our project. To this end, we are continuing to develop a hydraulic fracturing simulation capability within the Livermore Distinct Element Code (LDEC), a combined FEM/DEM analysis code with explicit solid-fluid mechanics coupling. LDEC simulations start from an initial fracture distribution which can be stochastically generated or upscaled from the statistics of an actual fracture distribution. During the hydraulic stimulation process, LDEC tracks the propagation of fractures and other modifications to the fracture system. The output is transferred to the Non-isothermal Unsaturated Flow and Transport (NUFT) code to capture heat transfer and flow at the reservoir scale. This approach is intended to offer flexibility in the types of analyses we can perform, including evaluating the effects of different system heterogeneities on the heat extraction rate as well as seismicity associated with geothermal operations. This paper details the basic methodology of our approach. Two numerical examples showing the capability and effectiveness of our simulator are also presented.
Fu, P; Johnson, S M; Hao, Y; Carrigan, C R
??This thesis presents a new method for determining mode II interlaminar fracture toughness in fiber reinforced polymers (FRP) using the essential work of fracture (EWF)� (more)
McKinney, Scott D
??Hydraulic fracturing is an important stimulation method for producing unconventional gas reserves. Natural fractures are present in many low-permeability gas environments and often provide important� (more)
Reynolds, Harris Allen
modeling fluid and heat flow in fractured porous media, Soc.flow through unsaturated fractured porous media, Proceedings of the Second International Symposium on Dynamics of Fluids
Wu, Yu-Shu; Pruess, Karsten
modeling fluid and heat flow in fractured porous media, Soc.flow through unsaturated fractured porous media, Proceedings of the Second International Symposium on Dynamics of Fluids
Wu, Yu-Shu; Pan, Lehua; Pruess, Karsten
Step-out Well | Open Energy Information
Step-out Well Step-out Well Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Step-out Well Details Activities (5) Areas (5) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Drilling Techniques Exploration Sub Group: Exploration Drilling Parent Exploration Technique: Exploration Drilling Information Provided by Technique Lithology: Drill cuttings are analyzed to determine lithology and mineralogy Stratigraphic/Structural: Fractures, faults, and geologic formations that the well passes through are identified and mapped Hydrological: Identify aquifers, reservoir boundaries, flow rates, fluid pressure, and chemistry Thermal: Direct temperature measurements from within the reservoir Dictionary.png Step-out Well: A well drilled outside of the proven reservoir boundaries to investigate a
This project consists of three key interrelated Phases, each focusing on the central issue of imaging and quantifying fractured reservoirs, through improved integration of the principles of rock physics, geology, and seismic wave propagation. This report summarizes the results of Phase I of the project. The key to successful development of low permeability reservoirs lies in reliably characterizing fractures. Fractures play a crucial role in controlling almost all of the fluid transport in tight reservoirs. Current seismic methods to characterize fractures depend on various anisotropic wave propagation signatures that can arise from aligned fractures. We are pursuing an integrated study that relates to high-resolution seismic images of natural fractures to the rock parameters that control the storage and mobility of fluids. Our goal is to go beyond the current state-of-the art to develop and demonstrate next generation methodologies for detecting and quantitatively characterizing fracture zones using seismic measurements. Our study incorporates 3 key elements: (1) Theoretical rock physics studies of the anisotropic viscoelastic signatures of fractured rocks, including up scaling analysis and rock-fluid interactions to define the factors relating fractures in the lab and in the field. (2) Modeling of optimal seismic attributes, including offset and azimuth dependence of travel time, amplitude, impedance and spectral signatures of anisotropic fractured rocks. We will quantify the information content of combinations of seismic attributes, and the impact of multi-attribute analyses in reducing uncertainty in fracture interpretations. (3) Integration and interpretation of seismic, well log, and laboratory data, incorporating field geologic fracture characterization and the theoretical results of items 1 and 2 above. The focal point for this project is the demonstration of these methodologies in the Marathon Oil Company Yates Field in West Texas.
Gary Mavko
San Juan Fracture Characterization Project: Status and current results
3 s sweep, 10 sweeps/source Arch Rock #1 Single Well Surveyin Fractured Rock P-wave S-wave P-wave S-wave RIW HW sourceRock #1 VSP Acquisition Single Offset, 9-C VSP P- and S-Wave Vibroseis Sources
Stimulation Technologies for Deep Well Completions
The Department of Energy (DOE) is sponsoring the Deep Trek Program targeted at improving the economics of drilling and completing deep gas wells. Under the DOE program, Pinnacle Technologies is conducting a study to evaluate the stimulation of deep wells. The objective of the project is to assess U.S. deep well drilling and stimulation activity, review rock mechanics and fracture growth in deep, high-pressure/temperature wells and evaluate stimulation technology in several key deep plays. An assessment of historical deep gas well drilling activity and forecast of future trends was completed during the first six months of the project; this segment of the project was covered in Technical Progress Report No. 1. During the next six months, efforts were primarily split between summarizing rock mechanics and fracture growth in deep reservoirs and contacting operators about case studies of deep gas well stimulation as documented in Technical Progress Report No. 2. This report details work done with Anadarko and ChevronTexaco in the Table Rock Field in Wyoming.
Simulation of fracture fluid cleanup and its effect on long-term recovery in tight gas reservoirs
In the coming decades, the world will require additional supplies of natural gas to meet the demand for energy. Tight gas reservoirs can be defined as reservoirs where the formation permeability is so low (flowback procedures, production strategy, and reservoir conditions. Residual polymer in the fracture can reduce the effective fracture permeability and porosity, reduce the effective fracture half-length, and limit the well productivity. Our ability to mathematically model the fundamental physical processes governing fluid recovery in hydraulic fractures in the past has been limited. In this research, fracture fluid damage mechanisms have been investigated, and mathematical models and computer codes have been developed to better characterize the cleanup process. The codes have been linked to a 3D, 3-phase simulator to model and quantify the fracture fluid cleanup process and its effect on long-term gas production performances. Then, a comprehensive systematic simulation study has been carried out by varying formation permeability, reservoir pressure, fracture length, fracture conductivity, yield stress, and pressure drawdown. On the basis of simulation results and analyses, new ways to improve fracture fluid cleanup have been provided. This new progress help engineers better understand fracture fluid cleanup, improve fracture treatment design, and increase gas recovery from tight sand reservoirs, which can be extremely important as more tight gas reservoirs are developed around the world.
Wang, Yilin
Nonisothermal injection tests in fractured reservoirs
The paper extends the analysis of nonisothermal pressure transient data to fractured reservoirs. Two cases are considered: reservoirs with predominantly horzontal fractures and reservoirs with predominantly vertical fractures. Effects of conductive heat transfer between the fractures and the rock matrix are modeled, and the resulting pressure transients evaluated. Thermal conduction tends to retard the movement of the thermal front in the fractures, which significantly affects the pressure transient data. The purpose of the numerical simulation studies is to provide methods for analyzing nonisothermal injection/falloff data for fractured reservoirs.
Cox, B.L.; Bodvarsson, G.S.
Monitoring hydraulic fracture growth: Laboratory experiments
Science Conference Proceedings (OSTI)
The authors carry out small-scale hydraulic fracture experiments to investigate the physics of hydraulic fracturing. The laboratory experiments are combined with time-lapse ultrasonic measurements with active sources using both compressional and shear-wave transducers. For the time-lapse measurements they focus on ultrasonic measurement changes during fracture growth. As a consequence they can detect the hydraulic fracture and characterize its shape and geometry during growth. Hence, this paper deals with fracture characterization using time-lapse acoustic data. Hydraulic fracturing is used in the oil and gas industry to stimulate reservoir production.
Groenenboom, J.; Dam, D.B. van
Hydrogen-Assisted Fracture: Materials Testing and Variables Governing Fracture
NLE Websites -- All DOE Office Websites (Extended Search)
Hydrogen-Assisted Fracture: Materials Hydrogen-Assisted Fracture: Materials Testing and Variables Governing Fracture Brian Somerday, Chris San Marchi, and Dorian Balch Sandia National Laboratories Livermore, CA Hydrogen Pipeline Working Group Workshop Augusta, GA August 30-31, 2005 SNL has 40+ years experience with effects of high-pressure hydrogen gas on materials * Design and maintenance of welded stainless steel pressure vessels for containment of high-pressure H 2 isotopes - Extensive testing of stainless steels exposed to high-pressure H 2 gas * Six-year program in 1970s focused on feasibility of using natural gas pipeline network for H 2 gas - Materials testing in high-pressure H 2 gas using laboratory specimens and model pipeline - Examined fusion zone and heat affected zones of welds * Active SNL staff have authored 70+ papers and organized 6
Sensitivity study on hydraulic well testing inversion using simulated annealing
For environmental remediation, management of nuclear waste disposal, or geothermal reservoir engineering, it is very important to evaluate the permeabilities, spacing, and sizes of the subsurface fractures which control ground water flow. Cluster variable aperture (CVA) simulated annealing has been used as an inversion technique to construct fluid flow models of fractured formations based on transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes an aperture of cluster of fracture elements, which are chosen randomly from a list of discrete apertures, to improve the match to observed pressure transients. The size of the clusters is held constant throughout the iterations. Sensitivity studies using simple fracture models with eight wells show that, in general, it is necessary to conduct interference tests using at least three different wells as pumping well in order to reconstruct the fracture network with a transmissivity contrast of one order of magnitude, particularly when the cluster size is not known a priori. Because hydraulic inversion is inherently non-unique, it is important to utilize additional information. The authors investigated the relationship between the scale of heterogeneity and the optimum cluster size (and its shape) to enhance the reliability and convergence of the inversion. It appears that the cluster size corresponding to about 20--40 % of the practical range of the spatial correlation is optimal. Inversion results of the Raymond test site data are also presented and the practical range of spatial correlation is evaluated to be about 5--10 m from the optimal cluster size in the inversion.
Nakao, Shinsuke; Najita, J.; Karasaki, Kenzi
A new method for determining fluid flow paths during hydraulic fracturing
Although hydraulic fracturing is a popular method for increasing the productivity of oil and gas wells, there is no direct way other than drilling additional boreholes to determine where the injected fluid has gone and thus what direction a fracture has propagated. Information about fluid flow paths is important for designing subsequent fracturing operations for nearby wells. Determining the locations and orientations of permeable fractures is also important in studies of potential toxic waste repositories where it is critical to understand fluid flow paths. We have developed a method for determining the orientations and locations of fractures along which fluid flows during hydraulic fracturing. The method is based on accurate determination of the locations of microseismic events, or microearthquakes, that accompany the hydraulic injection. By applying a pattern recognition technique to the locations of events from one hydraulic fracturing operation we find planes in the data along which we presume that the fluid has traveled. The planes determined using our method intersect the injection borehole and a second, nearby borehole, in regions where other data indicate that fractures are present.
Fehler, M.
Hydraulic-fracture diagnostic research. Final report, December 1989-December 1990
The results of the research in microseismic methods to determine hydraulic fracture dimensions during the contract were significant. The GRI Hydraulic Fracture Test Site (HFTS) development planning was a major effort. Ten meetings of the Planning Team were coordinated and hosted. A statement of the HFTS mission, scope, objectives, and requirements was created. The primary objectives were to provide for interdisciplinary experiments on fracture modeling and fracture diagnostics. A Conceptual Plan for the HFTS was compiled by Teledyne Geotech and distributed at the Project Advisors Group meeting. An experiment at the Shell South Belridge Field in California was a direct analog of the HFTS. Multiple fracture stimulations were monitored from 3 wells with cemented-in geophones. Methods of handling and processing large data volumes in real time were established. The final fracture geometry did not fit the circular model. Fracture diagnostics were monitored at two GRI cooperative wells: the Enron S. Hogsback No. 13-8A and the Phillips Ward C No. 11. Theoretical studies indicate that crack waves might be used as an estimate of fracture length. After applying advanced signal enhancement techniques to low-frequency signals from 14 surveys, it was concluded that the data from presently available sondes is contaminated by sonde resonances.
Fix, J.E.; Adair, R.G.; Clawson, G.E.; Lawhorn, W.S.; Mahrer, K.D.
Foam flow through a transparent rough-walled rock fracture
This paper presents an experimental study of nitrogen, water, and aqueous foam flow through a transparent replica of a natural rough-walled rock fracture with a hydraulic aperture of roughly 30 {mu}m. It is established that single-phase flow of both nitrogen and water is well described by analogy to flow between parallel plates. Inertial effects caused by fracture roughness become important in single-phase flow as the Reynolds number approaches 1. Foam exhibits effective control of gas mobility. Foam flow resistances are approximately 10 to 20 times greater than those of nitrogen over foam qualities spanning from 0.60 to 0.99 indicating effective gas-mobility control. Because previous studies of foam flow have focused mainly upon unfractured porous media, little information is available about foam flow mechanisms in fractured media. The transparency of the fracture allowed flow visualization and demonstrated that foam rheology in fractured media depends upon bubble shape and size. Changes in flow behavior are directly tied to transitions in bubble morphology.
Kovscek, A.; Tretheway, D.; Radke, C. [and others
This publication explains how to decontaminate and disinfect a well, test the well water and check for well damage after a flood.
Boellstorff, Diana; Dozier, Monty; Provin, Tony; Dictson, Nikkoal; McFarland, Mark L.
Acoustic methods for detecting water-filled fractures using commercial logging tools
The Los Alamos Scientific Laboratory Hot Dry Rock Geothermal Energy Development Project, under the Department of Energy and in cooperation with Dresser Atlas, has conducted single- and dual-well acoustic measurements to detect fractures in the artificial geothermal reservoir at the Fenton Hill New Mexico experimental site. The measurements were made using modified Dresser Atlas logging tools. Signals traversed distances of from 48 to 150 feet between two wells. Signals intersecting hydraulic fractures in the reservoir under both hydrostatic and pressurized conditions were simultaneously detected in both wells. Upon reservoir pressurization, signals along many ray paths were severely attenuated throughout their entire coda. In addition obvious shear wave arrivals were notably absent. The signals were processed to obtain Full-Wave Acoustic, Power, and Normalized Equi-Power Logs. Analysis of these logs identified the effective ''top'' of a region of hydraulically activated fractures and fractures intersecting the injection well behind casing.
Albright, J.N.; Aamodt, R.L.; Potter, R.M.; Spence, R.W.
here are from the first year of a five year project and include the discrimination of natural from drilling-induced fractures in wellbore image data in the four study wells,...
Wellness Planning Session Report
Wellness Planning Session Report September 12, 2008 #12;Wellness Planning Session Report Printed.............................................................................1 Explored what wellness program should look like at NMSU .......................2 Considered for the Wellness committee..................................2 Identified the next meeting date and meeting agenda
Castillo, Steven P.
Method for directional hydraulic fracturing
A method for directional hydraulic fracturing using borehole seals to confine pressurized fluid in planar permeable regions, comprising: placing a sealant in the hole of a structure selected from geologic or cemented formations to fill the space between a permeable planar component and the geologic or cemented formation in the vicinity of the permeable planar component; making a hydraulic connection between the permeable planar component and a pump; permitting the sealant to cure and thereby provide both mechanical and hydraulic confinement to the permeable planar component; and pumping a fluid from the pump into the permeable planar component to internally pressurize the permeable planar component to initiate a fracture in the formation, the fracture being disposed in the same orientation as the permeable planar component.
Swanson, David E. (West St. Paul, MN); Daly, Daniel W. (Crystal, MN)
Acoustic Character Of Hydraulic Fractures In Granite
Hydraulic fractures in homogeneous granitic rocks were logged with conventional acoustic-transit-time, acoustic-waveform, and acoustic-televiewer logging systems. Fractured intervals ranged in depth from 45 to 570m. and ...
Paillet, Frederick I.
Science Conference Proceedings (OSTI)
Robot assisted fracture reduction of femoral shaft fractures provides precise alignment while reducing the amount of intraoperative imaging. The connection between the robot and the fracture fragment should allow conventional intramedullary nailing, ... Keywords: Robot, femur shaft, fracture reduction, interface
T. S. Weber-Spickschen; M. Oszwald; R. Westphal; C. Krettek; F. Wahl; T. Gosling
Science Conference Proceedings (OSTI)
Multiphase fluid motion in unsaturated fractures and fracture networks involves complicated fluid dynamics, which is difficult to model using grid-based continuum methods. In this paper, the application of dissipative particle dynamics (DPD), a relatively ... Keywords: Dissipative particle dynamics (DPD), Fracture, Fracture flow, Smoothed particle hydrodynamics (SPH), Weight functions
Moubin Liu; Paul Meakin; Hai Huang
Effects of dry fractures on matrix diffusion in unsaturated fractured rocks
Symposium on Multiphase Transport in Porous Media, ASMEmultiphase heat and mass flow in unsaturated fractured porous
Seol, Yongkoo; Liu, Hui Hai; Bodvarsson, Gudmundur S.
Geothermal-Reservoir Well-Stimulation Program. Program status report
Seven experimental fracture stimulation treatments completed to date and the laboratory work performed to develop the stimulation technology are described. A discussion of the pre-stimulation and post-stimulation data and their evaluation is provided for each experiment. Six of the seven stimulation experiments were at least technically successful in stimulating the wells. The two fracture treatments in East Mesa 58-30 more than doubled the producing rate of the previously marginal producer. The two fracture treatments in Raft River and the two in Baca were all successful in obtaining significant production from previously nonproductive intervals. However, these treatments failed to establish commercial production due to deficiencies in either fluid temperature or flow rate. The acid etching treatment in the well at The Geysers did not have any material effect on producing rate.
Not Available
Summary of Linear Elastic Fracture Mechanics Concepts
Science Conference Proceedings (OSTI)
...in this Volume."Stress Intensity Factors"A brief summary of linear elastic fracture mechanics (LEFM) concepts
IN SITU STRESS, FRACTURE AND FLUID FLOW ANALYSIS-EAST FLANK OF THE COSO IN SITU STRESS, FRACTURE AND FLUID FLOW ANALYSIS-EAST FLANK OF THE COSO GEOTHERMAL FIELD Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: IN SITU STRESS, FRACTURE AND FLUID FLOW ANALYSIS-EAST FLANK OF THE COSO GEOTHERMAL FIELD Details Activities (1) Areas (1) Regions (0) Abstract: High rock temperatures, a high degree of fracturing, high tectonic stresses, and low permeability are the combination of qualities that define an ideal candidate-Enhanced Geothermal System (EGS) reservoir. The Coso Geothermal Field is an area where fluid temperatures exceeding 300°C have been measured at depths less than 10,000 feet and the reservoir is both highly fractured and tectonically stressed. Some of the wells within this portion of the reservoir are relatively impermeable,
Key challenges associated with the EGS reservoir development include the ability to reliably predict hydraulic fracturing and the deformation of natural fractures as well as estimating permeability evolution of the fracture network with time. We have developed a physics-based rock deformation and fracture propagation simulator by coupling a discrete element model (DEM) for fracturing with a network flow model. In DEM model, solid rock is represented by a network of discrete elements (often referred as particles) connected by various types of mechanical bonds such as springs, elastic beams or bonds that have more complex properties (such as stress-dependent elastic constants). Fracturing is represented explicitly as broken bonds (microcracks), which form and coalesce into macroscopic fractures when external and internal load is applied. The natural fractures are represented by a series of connected line segments. Mechanical bonds that intersect with such line segments are removed from the DEM model. A network flow model using conjugate lattice to the DEM network is developed and coupled with the DEM. The fluid pressure gradient exerts forces on individual elements of the DEM network, which therefore deforms the mechanical bonds and breaks them if the deformation reaches a prescribed threshold value. Such deformation/fracturing in turn changes the permeability of the flow network, which again changes the evolution of fluid pressure, intimately coupling the two processes. The intimate coupling between fracturing/deformation of fracture networks and fluid flow makes the meso-scale DEM- network flow simulations necessary in order to accurately evaluate the permeability evolution, as these methods have substantial advantages over conventional continuum mechanical models of elastic rock deformation. The challenges that must be overcome to simulate EGS reservoir stimulation, preliminary results, progress to date and near future research directions and opportunities will be discussed. Methodology for coupling the DEM model with continuum flow and heat transport models will also be discussed.
Shouchun Deng; Robert Podgorney; Hai Huang
The Department of Energy (DOE) is sponsoring a Deep Trek Program targeted at improving the economics of drilling and completing deep gas wells. Under the DOE program, Pinnacle Technologies is conducting a project to evaluate the stimulation of deep wells. The objective of the project is to assess U.S. deep well drilling & stimulation activity, review rock mechanics & fracture growth in deep, high pressure/temperature wells and evaluate stimulation technology in several key deep plays. Phase 1 was recently completed and consisted of assessing deep gas well drilling activity (1995-2007) and an industry survey on deep gas well stimulation practices by region. Of the 29,000 oil, gas and dry holes drilled in 2002, about 300 were drilled in the deep well; 25% were dry, 50% were high temperature/high pressure completions and 25% were simply deep completions. South Texas has about 30% of these wells, Oklahoma 20%, Gulf of Mexico Shelf 15% and the Gulf Coast about 15%. The Rockies represent only 2% of deep drilling. Of the 60 operators who drill deep and HTHP wells, the top 20 drill almost 80% of the wells. Six operators drill half the U.S. deep wells. Deep drilling peaked at 425 wells in 1998 and fell to 250 in 1999. Drilling is expected to rise through 2004 after which drilling should cycle down as overall drilling declines.
Stephen Wolhart
Production Trends of Shale Gas Wells
To obtain better well performance and improved production from shale gas reservoirs, it is important to understand the behavior of shale gas wells and to identify different flow regions in them over a period of time. It is also important to understand best fracture and stimulation practice to increase productivity of wells. These objectives require that accurate production analysis be performed. For accurate production analysis, it is important to analyze the production behavior of wells, and field production data should be interpreted in such a way that it will identify well parameters. This can be done by performing a detailed analysis on a number of wells over whole reservoirs. This study is an approach that will lead to identifying different flow regions in shale gas wells that include linear and bilinear flow. Important field parameters can be calculated from those observations to help improve future performance. The detailed plots of several wells in this study show some good numbers for linear and bilinear flow, and some unique observations were made. The purpose of this work is to also manage the large amount of data in such a way that they can be used with ease for future studies. A program was developed to automate the analysis and generation of different plots. The program can also be used to perform the simple calculations to calculate different parameters. The goal was to develop a friendly user interface that would facilitate reservoir analysis. Examples were shown for each flow period, i.e. linear and bilinear flow. Different plots were generated (e.g; Bob Plot (square root of time plot) and Fourth Root of Time Plot, that will help in measuring slopes and thus reservoir parameters such as fracture permeability and drainage area. Different unique cases were also observed that show a different behavior of well in one type of plot from another.
Khan, Waqar A.
Fractured shale reservoirs: Towards a realistic model
Science Conference Proceedings (OSTI)
Fractured shale reservoirs are fundamentally unconventional, which is to say that their behavior is qualitatively different from reservoirs characterized by intergranular pore space. Attempts to analyze fractured shale reservoirs are essentially misleading. Reliance on such models can have only negative results for fractured shale oil and gas exploration and development. A realistic model of fractured shale reservoirs begins with the history of the shale as a hydrocarbon source rock. Minimum levels of both kerogen concentration and thermal maturity are required for effective hydrocarbon generation. Hydrocarbon generation results in overpressuring of the shale. At some critical level of repressuring, the shale fractures in the ambient stress field. This primary natural fracture system is fundamental to the future behavior of the fractured shale gas reservoir. The fractures facilitate primary migration of oil and gas out of the shale and into the basin. In this process, all connate water is expelled, leaving the fractured shale oil-wet and saturated with oil and gas. What fluids are eventually produced from the fractured shale depends on the consequent structural and geochemical history. As long as the shale remains hot, oil production may be obtained. (e.g. Bakken Shale, Green River Shale). If the shale is significantly cooled, mainly gas will be produced (e.g. Antrim Shale, Ohio Shale, New Albany Shale). Where secondary natural fracture systems are developed and connect the shale to aquifers or to surface recharge, the fractured shale will also produce water (e.g. Antrim Shale, Indiana New Albany Shale).
Hamilton-Smith, T. [Applied Earth Science, Lexington, KY (United States)
Fracture patterns in graywacke outcrops at The Geysers geothermal field
The Geysers geothermal field covers an area of more than 35,000 acres and represents one of the most significant steam fields in the world. The heterogeneous nature of the reservoir, its fracture network and non-sedimentary rock distinguish it from ordinary sandstone reservoirs in terms of reservoir definition and evaluation (Stockton et al. 1984). Analysis of cuttings, record of steam entries, temperature and pressure surveys and spinner logs have contributed to an understanding of the subsurface geology and rock characteristics of the Geysers. Few conventional electrical log data are available for the main body of the reservoir. It is generally believed that while the fractures are the main conducts for fluid transport through the reservoirs, tight rocks between the major fractures contain the bulk of the fluid reserves. No independent measurement of liquid and vapor saturation can be made from the existing downhole tools. Pressure depletion in The Geysers geothermal field has become a major concern to the operators and utility companies in recent years. Plans for further development activities and future field management are contingent upon accurate computer modeling and definition of the field. The primary issues in reliable characterization of The Geysers field are the role of the rock matrix in holding liquid reserves and providing pressure support, the nature of fracture network, extent of liquid saturation in the reservoirs and injection pattern strategies to maximize heat recovery. Current modeling of The Geysers field is done through the use of general purpose geothermal reservoir simulators. Approaches employed include treating the reservoir as a single porosity equivalent or a dual porosity system. These simulators include formulation to represent transport of heat, steam and water. Heterogeneities are represented by spatial variations in formation or fracture permeability-thickness product, porosity or fluid saturations. Conceptual models based on dual porosity representations have been shown to duplicate the history. Prediction of future performance is, however, not reliable because of uncertainties in assumptions of the initial state of the reservoir, Specifically, several different initial state conditions have led to a fairly good match of the historical data. Selection of the exact initial conditions is a major dilemma. In dual porosity models, the complex nature of fracture network is formulated by a systematic, well-organized set of orthogonal fractures. Also, the exact nature of matrix-fracture interaction, and the role of adsorption and capillarity in pressure support are not well-defined.
Sammis, Charles G.; Lin Ji An; Ershaghi, I.
Fracture Permeability and In Situ Stress in the Dixie Valley, Nevada,
Fracture Permeability and In Situ Stress in the Dixie Valley, Nevada, Fracture Permeability and In Situ Stress in the Dixie Valley, Nevada, Geothermal Reservoir Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Fracture Permeability and In Situ Stress in the Dixie Valley, Nevada, Geothermal Reservoir Abstract Borehole televiewer, temperature and flowmeter logs and hydraulic fracturing stress measurements conducted in six wells penetrating a geothermal reservoir associated with the Stillwater fault zone in Dixie Valley, Nevada, were used to investigate the relationship between reservoir permeability and the contemporary in situ stress field. Data from wells drilled into productive and nonproductive segments of the Stillwater fault zone indicate that permeability in all wells is dominated by a relatively
Dynamics of window glass fracture in explosions
An exploratory study was conducted under the Architectural Surety Program to examine the possibility of modifying fracture of glass in the shock-wave environment associated with terrorist bombings. The intent was to explore strategies to reduce the number and severity of injuries resulting from those attacks. The study consisted of a series of three experiments at the Energetic Materials Research and Testing Center (EMRTC) of the New Mexico Institute of Mining and Technology at Socorro, NM, in which annealed and tempered glass sheets were exposed to blast waves at several different levels of overpressure and specific impulse. A preliminary assessment of the response of tempered glass to the blast environment suggested that inducing early failure would result in lowering fragment velocity as well as reducing the loading from the window to the structure. To test that possibility, two different and novel procedures (indentation flaws and spot annealing) were used to reduce the failure strength of the tempered glass while maintaining its ability to fracture into small cube-shaped fragments. Each experiment involved a comparison of the performance of four sheets of glass with different treatments.
Beauchamp, E.K.; Matalucci, R.V.
U.S. Energy Information Administration (EIA) Indexed Site
OIL & GAS FIELD OUTLINES FROM BUFFERED WELLS The VBA Code below builds oil & gas field boundary outlines (polygons) from buffered wells (points). Input well points layer must be a...
Science Conference Proceedings (OSTI)
A major goal of industry and the U.S. Department of Energy (DOE) fossil energy program is to increase gas reserves in tight-gas reservoirs. Infill drilling and hydraulic fracture stimulation in these reservoirs are important reservoir management strategies to increase production and reserves. Phase II of this DOE/cooperative industry project focused on optimization of infill drilling and evaluation of hydraulic fracturing in naturally-fractured tight-gas reservoirs. The cooperative project involved multidisciplinary reservoir characterization and simulation studies to determine infill well potential in the Mesaverde and Dakota sandstone formations at selected areas in the San Juan Basin of northwestern New Mexico. This work used the methodology and approach developed in Phase I. Integrated reservoir description and hydraulic fracture treatment analyses were also conducted in the Pecos Slope Abo tight-gas reservoir in southeastern New Mexico and the Lewis Shale in the San Juan Basin. This study has demonstrated a methodology to (1) describe reservoir heterogeneities and natural fracture systems, (2) determine reservoir permeability and permeability anisotropy, (3) define the elliptical drainage area and recoverable gas for existing wells, (4) determine the optimal location and number of new in-fill wells to maximize economic recovery, (5) forecast the increase in total cumulative gas production from infill drilling, and (6) evaluate hydraulic fracture simulation treatments and their impact on well drainage area and infill well potential. Industry partners during the course of this five-year project included BP, Burlington Resources, ConocoPhillips, and Williams.
Lawrence W. Teufel; Her-Yuan Chen; Thomas W. Engler; Bruce Hart
Active and passive seismic imaging of a hydraulic fracture in diatomite
This paper reports on a comprehensive set of experiments including remote- and treatment-well microseismic monitoring, interwell shear-wave shadowing, and surface tiltmeter arrays, that was used to monitor the growth of a hydraulic fracture in the Belridge diatomite. To obtain accurate measurements, and extensive subsurface network of geophones was cemented spanning the diatomite formation in three closely spaced observation wells around the well to be fracture treated. Data analysis indicates that the minifracture and main hydraulic fracture stimulations resulted in a nearly vertical fracture zone (striking N26{degrees}E) vertically segregated into two separate elements, the uppermost of which grew 60 ft above the perforated interval. The interwell seismic effects are consistent with a side process zone of reduced shear velocity, which remote-well microseismic data independently suggest may be as wide as 40 ft. The experiments indicate complicated processes occurring during hydraulic fracturing that have significant implications for stimulation, waterflooding, in fill drilling, and EOR. These processes are neither well understood nor included in current hydraulic fracture models.
Vinegar, H.J.; Wills, P.B.; De Martini, D.C. (Shell Development Co. (US))
Groundwater and Wells (Nebraska)
Energy.gov (U.S. Department of Energy (DOE))
This section describes regulations relating to groundwater protection, water wells, and water withdrawals, and requires the registration of all water wells in the state.
Geomechanical Simulation of Fluid-Driven Fractures
The project supported graduate students working on experimental and numerical modeling of rock fracture, with the following objectives: (a) perform laboratory testing of fluid-saturated rock; (b) develop predictive models for simulation of fracture; and (c) establish educational frameworks for geologic sequestration issues related to rock fracture. These objectives were achieved through (i) using a novel apparatus to produce faulting in a fluid-saturated rock; (ii) modeling fracture with a boundary element method; and (iii) developing curricula for training geoengineers in experimental mechanics, numerical modeling of fracture, and poroelasticity.
Makhnenko, R.; Nikolskiy, D.; Mogilevskaya, S.; Labuz, J.
Structural Settings Of Hydrothermal Outflow- Fracture Permeability
Settings Of Hydrothermal Outflow- Fracture Permeability Settings Of Hydrothermal Outflow- Fracture Permeability Maintained By Fault Propagation And Interaction Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Structural Settings Of Hydrothermal Outflow- Fracture Permeability Maintained By Fault Propagation And Interaction Details Activities (1) Areas (1) Regions (0) Abstract: Hydrothermal outflow occurs most commonly at the terminations of individual faults and where multiple faults interact. These areas of fault propagation and interaction are sites of elevated stress termed breakdown regions. Here, stress concentrations cause active fracturing and continual re-opening of fluid-flow conduits, permitting long-lived hydrothermal flow despite potential clogging of fractures due to mineral precipitation. As
Geothermal well log interpretation midterm report
Reservoir types are defined according to fluid phase and temperature, lithology, geologic province, pore geometry, and salinity and fluid chemistry. Improvements are needed in lithology and porosity definition, fracture detection, and thermal evaluation for more accurate interpretation. Further efforts are directed toward improving diagnostic techniques for relating rock characteristics and log response, developing petrophysical models for geothermal systems, and developing thermal evaluation techniques. The Geothermal Well Log Interpretation study and report has concentrated only on hydrothermal geothermal reservoirs. Other geothermal reservoirs (hot dry rock, geopressured, etc.) are not considered.
Sanyal, S.K.; Wells, L.E.; Bickham, R.E.
Interaction between Injection Points during Hydraulic Fracturing
We present a model of the hydraulic fracturing of heterogeneous poroelastic media. The formalism is an effective continuum model that captures the coupled dynamics of the fluid pressure and the fractured rock matrix and models both the tensile and shear failure of the rock. As an application of the formalism, we study the geomechanical stress interaction between two injection points during hydraulic fracturing (hydrofracking) and how this interaction influences the fracturing process. For injection points that are separated by less than a critical correlation length, we find that the fracturing process around each point is strongly correlated with the position of the neighboring point. The magnitude of the correlation length depends on the degree of heterogeneity of the rock and is on the order of 30-45 m for rocks with low permeabilities. In the strongly correlated regime, we predict a novel effective fracture-force that attracts the fractures toward the neighboring injection point.
Hals, Kjetil M D
Microseismic Tracer Particles for Hydraulic Fracturing
NLE Websites -- All DOE Office Websites (Extended Search)
Microseismic Tracer Particles for Hydraulic Fracturing Microseismic Tracer Particles for Hydraulic Fracturing Microseismic Tracer Particles for Hydraulic Fracturing Scientists at Los Alamos National Laboratory have developed a method by which microseismic events can be discriminated/detected that correspond to only the portion of the hydraulic fracture that contains the proppant material and can be expected to be conductive to the flow of oil and gas. July 3, 2013 Microseismic Tracer Particles for Hydraulic Fracturing Figure 1: A graph of ionic conductivity as a function of temperature for the anti-perovskite Li3OCl. Available for thumbnail of Feynman Center (505) 665-9090 Email Microseismic Tracer Particles for Hydraulic Fracturing Applications: Oil and gas production Geophysical exploration Benefits: Tracks the disposition of material in a hydraulic fracturing
Well Flix's in the Well-U library. These DVD's have been made available so employees may learn about a variety of fitness for a one-week basis at no cost. Contact Well U at firstname.lastname@example.com for DVD rental. Click the link
Portman, Douglas
Well development with acid wool
This paper describes a unique method to prevent the lost circulation of drilling fluids in fractured bedrock aquifers. The method utilizes acid wool to bridge fractures and prevent the migration of these fluids in to the reservoir. This wool material collects the mud on its surface and allows it to be removed during development. The wool is produced from melted silic-carbonate rock and is dissolved using hydrochloric acid. The timing and methodology of installation is provided.
Hanna, T.M. (Hydrologic Consultants Inc., Lakewood, CO (USA)); Rothauge, F. (Quality Drilling Fluids Engineering Inc., Longmont, CO (USA))
improving production by hydraulic fracturing 8 the focus otfor fractures. (d) Hydraulic Fracturing: The model has been
Wang, J.S.Y.
Naturally fractured tight gas reservoir detection optimization
The goal of the work this quarter has been to partition and high-grade the Greater Green River basin for exploration efforts in the Upper Cretaceous tight gas play and to initiate resource assessment of the basin. The work plan for the quarter of July 1-September 30, 1998 comprised three tasks: (1) Refining the exploration process for deep, naturally fractured gas reservoirs; (2) Partitioning of the basin based on structure and areas of overpressure; (3) Examination of the Kinney and Canyon Creek fields with respect to the Cretaceous tight gas play and initiation of the resource assessment of the Vermilion sub-basin partition (which contains these two fields); and (4) Initiation analysis of the Deep Green River Partition with respect to the Stratos well and assessment of the resource in the partition.
Optimization Online - Dynamic sampling algorithms for multi-stage ...
Dec 18, 2010... of hydro-thermal scheduling in the New Zealand electricity system. ... Citation: Technical report, Electric Power Optimization Centre,�...
Span-Wise Mixing in a Multi-Stage Compressor
NLE Websites -- All DOE Office Websites (Extended Search)
Camci) 036 * Phenomena that have eluded gas turbine designers include the effects of rotor-stator interactions and the physics of mixing of velocity, pressure, temperature and...
An open framework for extensible multi-stage bioinformatics software
Science Conference Proceedings (OSTI)
In research labs, there is often a need to customise software at every step in a given bioinformatics workflow, but traditionally it has been difficult to obtain both a high degree of customisability and good performance. Performance-sensitive tools ...
Gabriel Keeble-Gagn�re; Johan Nystr�m-Persson; Matthew I. Bellgard; Kenji Mizuguchi
The value of multi-stage stochastic programming in capacity ...
Apr 29, 2005 ... Abstract: This paper addresses a general class of capacity planning problems under uncertainty, which arises, for example, in semiconductor�...
Improving supply chain resilience by multi-stage supply chain
Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...
Yang, Jingxia, M. Eng, Massachusetts Institute of Technology
Improve supply chain resilience by multi-stage supply chain
Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...
Xu, Jie, M. Eng. Massachusetts Institute of Technology
Optimization Online - Solving multi-stage stochastic mixed integer ...
Jan 26, 2012 ... Randomness takes place only in the prices on which the ... Finally, a numerical test on a real problem in energy market is provided. Keywords:�...
Multi-stage catalyst systems and uses thereof
Catalyst systems and methods provide benefits in reducing the content of nitrogen oxides in a gaseous stream containing nitric oxide (NO), hydrocarbons, carbon monoxide (CO), and oxygen (O.sub.2). The catalyst system comprises an oxidation catalyst comprising a first metal supported on a first inorganic oxide for catalyzing the oxidation of NO to nitrogen dioxide (NO.sub.2), and a reduction catalyst comprising a second metal supported on a second inorganic oxide for catalyzing the reduction of NO.sub.2 to nitrogen (N.sub.2).
Ozkan, Umit S. (Worthington, OH); Holmgreen, Erik M. (Columbus, OH); Yung, Matthew M. (Columbus, OH)
Dynamic sampling algorithms for multi'stage stochastic programs ...
Feb 9, 2011 ... hydro'electricity generation and generating from thermal plant over some ... carried out during a visit by the second author to the Electric Power�...
A constraint sampling approach for multi-stage robust optimization
Nov 25, 2010 ... reflects the non-anticipative nature of the decision process and ensures the ... Although the distribution P does not play a role per se in problem R, ..... [1981]. Proof of Corollary 1 In Calafiore [2009] it was shown that ...... For each of the parameters recorded, compute statistics over the 100 problem instances.
Optimal fracture stimulation of a moderate-permeability reservoir; Kuparuk River Unit, Alaska
Sixty-five percent of the reserves of the Kuparuk River field, the second-largest producing oil field in the U.S., is contained in a 20- 80-md-permeability sandstone. This paper provides details of stimulation design advances made over the past 3 years in this formation. The design steps for optimizing fracture treatments in a moderate-permeability formation require primary emphasis on fracture conductivity rather than on treatment size or fracture length. This philosophy was used for the 140 new wells documented in this paper. Treatment size was gradually increased once a commensurate increase in fracture conductivity was obtained. Applying the new design to the refracturing of 88 producing wells in the field resulted in an incremental 40,000 BOPD, a significant portion of the field's 300,000 BOPD.
Pearson, C.M.; Bond, A.J.; Eck, M.E.; Lynch, K.W. (Arco Alaska, Inc. (US))
Zero Discharge Water Management for Horizontal Shale Gas Well Development
Hydraulic fracturing technology (fracking), coupled with horizontal drilling, has facilitated exploitation of huge natural gas (gas) reserves in the Devonian-age Marcellus Shale Formation (Marcellus) of the Appalachian Basin. The most-efficient technique for stimulating Marcellus gas production involves hydraulic fracturing (injection of a water-based fluid and sand mixture) along a horizontal well bore to create a series of hydraulic fractures in the Marcellus. The hydraulic fractures free the shale-trapped gas, allowing it to flow to the well bore where it is conveyed to pipelines for transport and distribution. The hydraulic fracturing process has two significant effects on the local environment. First, water withdrawals from local sources compete with the water requirements of ecosystems, domestic and recreational users, and/or agricultural and industrial uses. Second, when the injection phase is over, 10 to 30% of the injected water returns to the surface. This water consists of flowback, which occurs between the completion of fracturing and gas production, and produced water, which occurs during gas production. Collectively referred to as returned frac water (RFW), it is highly saline with varying amounts of organic contamination. It can be disposed of, either by injection into an approved underground injection well, or treated to remove contaminants so that the water meets the requirements of either surface release or recycle use. Depending on the characteristics of the RFW and the availability of satisfactory disposal alternatives, disposal can impose serious costs to the operator. In any case, large quantities of water must be transported to and from well locations, contributing to wear and tear on local roadways that were not designed to handle the heavy loads and increased traffic. The search for a way to mitigate the situation and improve the overall efficiency of shale gas production suggested a treatment method that would allow RFW to be used as make-up water for successive fracs. RFW, however, contains dissolved salts, suspended sediment and oils that may interfere with fracking fluids and/or clog fractures. This would lead to impaired well productivity. The major technical constraints to recycling RFW involves: identification of its composition, determination of industry standards for make-up water, and development of techniques to treat RFW to acceptable levels. If large scale RFW recycling becomes feasible, the industry will realize lower transportation and disposal costs, environmental conflicts, and risks of interruption in well development schedules.
Paul Ziemkiewicz; Jennifer Hause; Raymond Lovett; David Locke Harry Johnson; Doug Patchen
SPHDOE 35396 Analysis of Hydrofracture Geometry and Matrix/Fracture Interactions During
the perforated interval of the upper injection well suggests that a horizontal fracture, or network of natural that roughly 43 percent of the total injected steam migrated above the perforations of the injection well view of the Phase II pilot area including injection, production, and monitoring wells. The two
Patzek, Tadeusz W.
Proceedings of the Second International Symposium on Dynamics of Fluids in Fractured Rock
new fracture surface by hydraulic fracturing. Termination ofwas impossible until hydraulic fracturing was applied. ForFor conventional hydraulic fracturing, this is not crucial
Faybishenko, Boris; Witherspoon, Paul A.
responses during hydraulic fracturing, and aid developmentFracture Monitoring Hydraulic fracturing is a method forfluids" used for hydraulic fracturing, the above frequencies
Nelson, J.T.
Irradiation Effects on Human Cortical Bone Fracture Behavior
NLE Websites -- All DOE Office Websites (Extended Search)
Irradiation Effects on Human Irradiation Effects on Human Cortical Bone Fracture Behavior Irradiation Effects on Human Cortical Bone Fracture Behavior Print Wednesday, 28 July 2010 00:00 Human bone is strong but still fallible. To better predict fracturing in bone, researchers need a mechanistic framework to understand the changes taking place on different size scales within bone, as well as the role of sustained irradiation damage. Combining in situ mechanical testing with synchrotron x-ray diffraction imaging and/or tomography, is a popular method of investigating micrometer deformation and fracture behavior in bone. However, the role that irradiation plays in these high-exposure experiments, and how it affects the properties of bone tissue, are not yet fully understood. A team of researchers led by Robert O. Ritchie at the Lawrence Berkeley National Laboratory and the University of California, Berkeley used synchrotron radiation micro-tomography at Advanced Light Source Beamline 8.3.2 to investigate changes in crack path and toughening mechanisms in human cortical bone with increased exposure to radiation, finding that exposure to high levels of irradiation can lead to drastic losses in strength, ductility, and toughness.
Irradiation Effects on Human Cortical Bone Fracture Behavior
NLE Websites -- All DOE Office Websites (Extended Search)
Irradiation Effects on Human Cortical Bone Fracture Behavior Print Irradiation Effects on Human Cortical Bone Fracture Behavior Print Human bone is strong but still fallible. To better predict fracturing in bone, researchers need a mechanistic framework to understand the changes taking place on different size scales within bone, as well as the role of sustained irradiation damage. Combining in situ mechanical testing with synchrotron x-ray diffraction imaging and/or tomography, is a popular method of investigating micrometer deformation and fracture behavior in bone. However, the role that irradiation plays in these high-exposure experiments, and how it affects the properties of bone tissue, are not yet fully understood. A team of researchers led by Robert O. Ritchie at the Lawrence Berkeley National Laboratory and the University of California, Berkeley used synchrotron radiation micro-tomography at Advanced Light Source Beamline 8.3.2 to investigate changes in crack path and toughening mechanisms in human cortical bone with increased exposure to radiation, finding that exposure to high levels of irradiation can lead to drastic losses in strength, ductility, and toughness.
Feasibility of an acoustic technique for fracture detection
A field experiment was conducted at a granite quarry to determine the feasibility of an acoustic, downhole technique for location of fractures in the vicinity of boreholes. The frequency used in this test was about 5 kHz; a frequency well above the seismic frequency commonly used in reservoir evaluations. An existing flame-cut slot in the granite at the test site was filled with water to simulate a fracture. A high-energy piezoelectric transmitter was located in a borehole 8 meters from the water-filled slot, and a commercial piezoelectric transducer was used as a receiver in a borehole 4 meters from the slot. Both transducers could be rotated for maximum transmission or reception for either the compressional wave or the shear wave. During the experiment, reflections from the simulated fracture were obtained with the transducers oriented only for shear wave illumination and detection. These test results suggest that a high-frequency shear wave can be used to detect fractures located away from a borehole. 2 refs., 2 figs.
Chang, H.T.
Irradiation Effects on Human Cortical Bone Fracture Behavior
NLE Websites -- All DOE Office Websites (Extended Search)
Irradiation Effects on Human Cortical Bone Fracture Behavior Print Irradiation Effects on Human Cortical Bone Fracture Behavior Print Human bone is strong but still fallible. To better predict fracturing in bone, researchers need a mechanistic framework to understand the changes taking place on different size scales within bone, as well as the role of sustained irradiation damage. Combining in situ mechanical testing with synchrotron x-ray diffraction imaging and/or tomography, is a popular method of investigating micrometer deformation and fracture behavior in bone. However, the role that irradiation plays in these high-exposure experiments, and how it affects the properties of bone tissue, are not yet fully understood. A team of researchers led by Robert O. Ritchie at the Lawrence Berkeley National Laboratory and the University of California, Berkeley used synchrotron radiation micro-tomography at Advanced Light Source Beamline 8.3.2 to investigate changes in crack path and toughening mechanisms in human cortical bone with increased exposure to radiation, finding that exposure to high levels of irradiation can lead to drastic losses in strength, ductility, and toughness.
Irradiation Effects on Human Cortical Bone Fracture Behavior
NLE Websites -- All DOE Office Websites (Extended Search)
Irradiation Effects on Human Cortical Bone Fracture Behavior Print Irradiation Effects on Human Cortical Bone Fracture Behavior Print Human bone is strong but still fallible. To better predict fracturing in bone, researchers need a mechanistic framework to understand the changes taking place on different size scales within bone, as well as the role of sustained irradiation damage. Combining in situ mechanical testing with synchrotron x-ray diffraction imaging and/or tomography, is a popular method of investigating micrometer deformation and fracture behavior in bone. However, the role that irradiation plays in these high-exposure experiments, and how it affects the properties of bone tissue, are not yet fully understood. A team of researchers led by Robert O. Ritchie at the Lawrence Berkeley National Laboratory and the University of California, Berkeley used synchrotron radiation micro-tomography at Advanced Light Source Beamline 8.3.2 to investigate changes in crack path and toughening mechanisms in human cortical bone with increased exposure to radiation, finding that exposure to high levels of irradiation can lead to drastic losses in strength, ductility, and toughness.
Irradiation Effects on Human Cortical Bone Fracture Behavior
NLE Websites -- All DOE Office Websites (Extended Search)
Irradiation Effects on Human Cortical Bone Fracture Behavior Print Irradiation Effects on Human Cortical Bone Fracture Behavior Print Human bone is strong but still fallible. To better predict fracturing in bone, researchers need a mechanistic framework to understand the changes taking place on different size scales within bone, as well as the role of sustained irradiation damage. Combining in situ mechanical testing with synchrotron x-ray diffraction imaging and/or tomography, is a popular method of investigating micrometer deformation and fracture behavior in bone. However, the role that irradiation plays in these high-exposure experiments, and how it affects the properties of bone tissue, are not yet fully understood. A team of researchers led by Robert O. Ritchie at the Lawrence Berkeley National Laboratory and the University of California, Berkeley used synchrotron radiation micro-tomography at Advanced Light Source Beamline 8.3.2 to investigate changes in crack path and toughening mechanisms in human cortical bone with increased exposure to radiation, finding that exposure to high levels of irradiation can lead to drastic losses in strength, ductility, and toughness.
Fluid Flow Within Fractured Porous Media
Science Conference Proceedings (OSTI)
Fractures provide preferential flow paths to subterranean fluid flows. In reservoir scale modeling of geologic flows fractures must be approximated by fairly simple formulations. Often this is accomplished by assuming fractures are parallel plates subjected to an applied pressure gradient. This is known as the cubic law. An induced fracture in Berea sandstone has been digitized to perform numerical flow simulations. A commercially available computational fluid dynamics software package has been used to solve the flow through this model. Single phase flows have been compared to experimental works in the literature to evaluate the accuracy with which this model can be applied. Common methods of fracture geometry classification are also calculated and compared to experimentally obtained values. Flow through regions of the fracture where the upper and lower fracture walls meet (zero aperture) are shown to induce a strong channeling effect on the flow. This model is expanded to include a domain of surrounding porous media through which the flow can travel. The inclusion of a realistic permeability in this media shows that the regions of small and zero apertures contribute to the greatest pressure losses over the fracture length and flow through the porous media is most prevalent in these regions. The flow through the fracture is shown to be the largest contributor to the net flow through the media. From this work, a novel flow relationship is proposed for flow through fractured media.
Crandall, D.M.; Ahmadi, G. (Clarkson Univ., Potsdam, NY); Smith, D.H.; Bromhal, G.S.
??A well-centered simplex is a simplex whose circumcenter lies in its interior, and a well-centered mesh is a simplicial mesh in which every simplex is� (more)
Vanderzee, Evan B.
Energy.gov (U.S. Department of Energy (DOE))
Class I, III, IV and V injection wells require a permit issued by the Executive Director of the Department of Environmental Quality; Class V injection wells utilized in the remediation of...
Geothermal well stimulation treatments
The behavior of proppants in geothermal environments and two field experiments in well stimulation are discussed. (MHR)
Hanold, R.J.
Wellness, Health & Counseling Services
Wellness, Health & Counseling Services Dr. Marcelle Holmes Assistant Vice Chancellor CARE Career Student Health Center #12;The mission of the Wellness, Health & Counseling Services cluster is to support · Dedicated to promoting principles of wellness, prevention and healthy life-style choices for students
Stanford, Kyle
Characterization of EGS Fracture Network Lifecycles
Geothermal energy is relatively clean, and is an important non-hydrocarbon source of energy. It can potentially reduce our dependence on fossil fuels and contribute to reduction in carbon emissions. High-temperature geothermal areas can be used for electricity generation if they contain permeable reservoirs of hot water or steam that can be extracted. The biggest challenge to achieving the full potential of the nation�s resources of this kind is maintaining and creating the fracture networks required for the circulation, heating, and extraction of hot fluids. The fundamental objective of the present research was to understand how fracture networks are created in hydraulic borehole injection experiments, and how they subsequently evolve. When high-pressure fluids are injected into boreholes in geothermal areas, they flow into hot rock at depth inducing thermal cracking and activating critically stressed pre-existing faults. This causes earthquake activity which, if monitored, can provide information on the locations of the cracks formed, their time-development and the type of cracking underway, e.g., whether shear movement on faults occurred or whether cracks opened up. Ultimately it may be possible to monitor the critical earthquake parameters in near-real-time so the information can be used to guide the hydraulic injection while it is in progress, e.g., how to adjust factors such as injectate pressure, volume and temperature. In order to achieve this, it is necessary to mature analysis techniques and software that were, at the start of this project, in an embryonic developmental state. Task 1 of the present project was to develop state-of-the-art techniques and software for calculating highly accurate earthquake locations, earthquake source mechanisms (moment tensors) and temporal changes in reservoir structure. Task 2 was to apply the new techniques to hydrofracturing (Enhanced Geothermal Systems, or �EGS�) experiments performed at the Coso geothermal field, in order to enhance productivity there. Task 3 was to interpret the results jointly with other geological information in order to provide a consistent physical model. All of the original goals of the project have been achieved. An existing program for calculating accurate relative earthquake locations has been enhanced by a technique to improve the accuracy of earthquake arrival-time measurements using waveform cross-correlation. Error analysis has been added to pre-existing moment tensor software. New seismic tomography software has been written to calculate changes in structure that could be due, for example, to reservoir depletion. Data processing procedures have been streamlined and web tools developed for rapid dissemination of the results, e.g., to on-site operations staff. Application of the new analysis tools to the Coso geothermal field has demonstrated the effective use of the techniques and provided important case histories to guide the style of future applications. Changes in reservoir structure with time are imaged throughout the upper 3 km, identifying the areas where large volumes of fluid are being extracted. EGS hydrofracturing experiments in two wells stimulated a nearby fault to the south that ruptured from south to north. The position of this fault could be precisely mapped and its existence was confirmed by surface mapping and data from a borehole televiewer log. No earthquakes occurred far north of the injection wells, suggesting that the wells lie near the northern boundary of the region of critically stressed faults. Minor en-echelon faults were also activated. Significant across-strike fluid flow occurred. The faults activated had significant crack-opening components, indicating that the hydraulic fracturing created open cavities at depth. The fluid injection changed the local stress field orientation and thus the mode of failure was different from the normal background. Initial indications are that the injections modulated stress release, seismicity and natural fracture system evolution for periods of up to months. The research demon
Gillian R. Foulger
The key to producing gas from tight gas reservoirs is to create a long, highly conductive flow path, via the placement of a hydraulic fracture, to stimulate flow from the reservoir to the wellbore. Viscous fluid is used to transport proppant into the fracture. However, these same viscous fluids need to break to a thin fluid after the treatment is over so that the fracture fluid can be cleaned up. In shallower, lower temperature (less than 250�F) reservoirs, the choice of a fracture fluid is very critical to the success of the treatment. Current hydraulic fracturing methods in unconventional tight gas reservoirs have been developed largely through ad-hoc application of low-cost water fracs, with little optimization of the process. It seems clear that some of the standard tests and models are missing some of the physics of the fracturing process in low-permeability environments. A series of the extensive laboratory "dynamic fracture conductivity" tests have been conducted. Dynamic fracture conductivity is created when proppant slurry is pumped into a hydraulic fracture in low permeability rock. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially, we pump proppant/ fracturing fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. Test results indicate that increasing gel concentration decreases retained fracture conductivity for a constant gas flow rate and decreasing gas flow rate decreases retained fracture conductivity. Without breaker, the damaging effect of viscous hydraulic fracturing fluids on the conductivity of proppant packs is significant at temperature of 150�F. Static conductivity testing results in higher retained fracture conductivity when compared to dynamic conductivity testing.
Marpaung, Fivman
The key to producing gas from tight gas reservoirs is to create a long, highly conductive flow path, via the placement of a hydraulic fracture, to stimulate flow from the reservoir to the wellbore. Viscous fluid is used to transport proppant into the fracture. However, these same viscous fluids need to break to a thin fluid after the treatment is over so that the fracture fluid can be cleaned up. In shallower, lower temperature (less than 250oF) reservoirs, the choice of a fracture fluid is very critical to the success of the treatment. Current hydraulic fracturing methods in unconventional tight gas reservoirs have been developed largely through ad-hoc application of low-cost water fracs, with little optimization of the process. It seems clear that some of the standard tests and models are missing some of the physics of the fracturing process in low-permeability environments. A series of the extensive laboratory �dynamic fracture conductivity� tests have been conducted. Dynamic fracture conductivity is created when proppant slurry is pumped into a hydraulic fracture in low permeability rock. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially, we pump proppant/ fracturing fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. Test results indicate that increasing gel concentration decreases retained fracture conductivity for a constant gas flow rate and decreasing gas flow rate decreases retained fracture conductivity. Without breaker, the damaging effect of viscous hydraulic fracturing fluids on the conductivity of proppant packs is significant at temperature of 150oF. Static conductivity testing results in higher retained fracture conductivity when compared to dynamic conductivity testing.
Marpaung, Fivman
PrimeEnergy/DOE/GRI slant well. Final report
Science Conference Proceedings (OSTI)
This report presents final results of the Sterling Boggs 1240 slant well. Objectives of the project were (1) to test the potential for improved recovery efficiency in a fractured Devonian Shale reservoir from a directionally drilled well, (2) to perform detailed tests of reservoir properties and completion methods, and (3) to provide technology to industry which may ultimately improve the economics of drilling in the Devonian Shale and thereby stimulate development of its resources.
Drimal, C.E.; Muncey, G.; Carden, R.
Science Conference Proceedings (OSTI)
This report summarizes the work carried out during the period of September 29, 2000 to September 28, 2001 under DOE Research Contract No. DE-FC26-00BC15308. Our goal is to establish an integrated methodology of fractured reservoir characterization and show how that can be incorporated into fluid flow simulation. We have made progress in the characterization of mineral infilling of natural fractures. The main advancement in this regard was to recognize the strong interplay between diagenetic and mechanical processes. We accomplished several firsts in documenting and quantifying these processes, including documenting the range of emergent threshold in several formations and quantifying the internal structures of crack-seal bridges in fractures. These results will be the basis for an appreciation of fracture opening and filling rates that go well beyond our original goals. Looking at geochemical modeling of fracture infilling, our theoretical analysis addressed the problem of calcite precipitation in a fracture. We have built a model for the deposition of calcite within a fracture. The diagenetic processes of dissolution and partial cementation are key controls on the creation and distribution of natural fractures within hydrocarbon reservoirs. Even with extensive data collection, fracture permeability still creates uncertainty in reservoir description and the prediction of well performance. Data on the timing and stages of diagenetic events can provide explanation as to why, when and where natural fractures will be open and permeable. We have been pursuing the fracture mechanics testing of a wide range of rocks, particularly sandstone using a key rock property test that has hitherto not been widely applied to sedimentary rocks. A major accomplishment in this first year has been to identify sample suites available in the core repository at the University of Texas that represent a wide range of diagenetic alteration and to begin to test these samples. The basis for the fluid flow simulations to be carried out in this part of the project is the adequate spatial characterization of fracture networks. Our initial focus has been on the tendency of fracture sets to cluster into highly fracture zones that are often widely separated. Our preliminary modeling work shows the extent of this clustering to be controlled by the subcritical fracture index of the material. With continued progress, we move toward an integrated fracture characterization methodology that will ultimately be applied through detailed reservoir simulation.
Jon E. Olson; Larry W. Lake; Steve E. Laubach
U.S. Energy Information Administration (EIA) Indexed Site
OIL & GAS FIELD OUTLINES FROM BUFFERED WELLS OIL & GAS FIELD OUTLINES FROM BUFFERED WELLS The VBA Code below builds oil & gas field boundary outlines (polygons) from buffered wells (points). Input well points layer must be a feature class (FC) with the following attributes: Field_name Buffer distance (can be unique for each well to represent reservoirs with different drainage radii) ...see figure below. Copy the code into a new module. Inputs: In ArcMap, data frame named "Task 1" Well FC as first layer (layer 0). Output: Polygon feature class in same GDB as the well points FC, with one polygon field record (may be multiple polygon rings) per field_name. Overlapping buffers for the same field name are dissolved and unioned (see figure below). Adds an attribute PCTFEDLAND which can be populated using the VBA
A finite element model for three dimensional hydraulic fracturing
Science Conference Proceedings (OSTI)
This paper is devoted to the development of a model for the numerical simulation of hydraulic fracturing processes with 3d fracture propagation. It takes into account the effects of fluid flow inside the fracture, fluid leak-off through fracture walls ... Keywords: boundary elements, finite elements, hydraulic fracturing, petroleum recovery
Philippe R. B. Devloo; Paulo Dore Fernandes; S�nia M. Gomes; Cedric Marcelo Augusto Ayala Bravo; Renato Gomes Damas
A set of vertical extension fractures, striking N-S to NNE-SSW but with local variations, is present in both the outcrop and subsurface in both Mesaverde and Dakota sandstones. Additional sets of conjugate shear fractures have been recognized in outcrops of Dakota strata and may be present in the subsurface. However, the deformation bands prevalent locally in outcrops in parts of the basin as yet have no documented subsurface equivalent. The immature Mesaverde sandstones typically contain relatively long, irregular extension fractures, whereas the quartzitic Dakota sandstones contain short, sub-parallel, closely spaced, extension fractures, and locally conjugate shear planes as well. Outcrops typically display secondary cross fractures which are rare in the subsurface, although oblique fractures associated with local structures such as the Hogback monocline may be present in similar subsurface structures. Spacings of the bed-normal extension fractures are approximately equal to or less than the thicknesses of the beds in which they formed, in both outcrop and subsurface. Fracture intensities increase in association with faults, where there is a gradation from intense fracturing into fault breccia. Bioturbation and minimal cementation locally inhibited fracture development in both formations, and the vertical limits of fracture growth are typically at bedding/lithology contrasts. Fracture mineralizations have been largely dissolved or replaced in outcrops, but local examples of preserved mineralization show that the quartz and calcite common to subsurface fractures were originally present in outcrop fractures. North-south trending compressive stresses created by southward indentation of the San Juan dome area (where Precambrian rocks are exposed at an elevation of 14,000 ft) and northward indentation of the Zuni uplift, controlled Laramide-age fracturing. Contemporaneous right-lateral transpressive wrench motion due to northeastward translation of the basin was both concentrated at the basin margins (Nacimiento uplift and Hogback monocline on east and west edges respectively) and distributed across the strata depth.
Geothermal Well Technology Program
The high cost of drilling and completing geothermal wells is an impediment to the development of geothermal energy resources. Technological deficiencies in rotary drilling techniques are evidenced when drilling geothermal wells. The Division of Geothermal Energy (DGE) of the U.S. Department of Energy has initiated a program aimed at developing new drilling and completion techniques for geothermal wells. The goals of this program are to reduce well costs by 25% by 1982 and by 50% by 1986. An overview of the program is presented. Program justification which relates well cost to busbar energy cost and to DGE power-on-line goals is presented. Technological deficiencies encountered when current rotary drilling techniques are used for geothermal wells are discussed. A program for correcting these deficiencies is described.
Varnado, S.G.
43 43 Varnish cache server Browse Upload data GDR 429 Throttled (bot load) Error 429 Throttled (bot load) Throttled (bot load) Guru Meditation: XID: 2142280543 Varnish cache server well Dataset Summary Description The California Division of Oil, Gas, and Geothermal Resources contains oil, gas, and geothermal data for the state of California. Source California Division of Oil, Gas, and Geothermal Resources Date Released February 01st, 2011 (3 years ago) Date Updated Unknown Keywords California data gas geothermal oil well Data application/vnd.ms-excel icon California district 1 wells (xls, 10.1 MiB) application/vnd.ms-excel icon California district 2 wells (xls, 4 MiB) application/vnd.ms-excel icon California district 3 wells (xls, 3.8 MiB) application/zip icon California district 4 wells (zip, 11.2 MiB)
Natural and Induced Fracture Diagnostics from 4-D VSP Low Permeability Gas Reservoirs
Tight gas sand reservoirs generally contain thick gas-charged intervals that often have low porosity and very low permeability. Natural and induced fractures provide the only means of production. The objective of this work is to locate and characterize natural and induced fractures from analysis of scattered waves recorded on 4-D (time lapse) VSP data in order to optimize well placement and well spacing in these gas reservoirs. Using model data simulating the scattering of seismic energy from hydraulic fractures, we first show that it is possible to characterize the quality of fracturing based upon the amount of scattering. In addition, the picked arrival times of recorded microseismic events provide the velocity moveout for isolating the scattered energy on the 4-D VSP data. This concept is applied to a field dataset from the Jonah Field in Wyoming to characterize the quality of the induced hydraulic fractures. The time lapse (4D) VSP data from this field are imaged using a migration algorithm that utilizes shot travel time tables derived from the first breaks of the 3D VSPs and receiver travel time tables based on the microseismic arrival times and a regional velocity model. Four azimuthally varying shot tables are derived from picks of the first breaks of over 200 VSP records. We create images of the fracture planes through two of the hydraulically fractured wells in the field. The scattered energy shows correlation with the locations of the microseismic events. In addition, the azimuthal scattering is different from the azimuthal reflectivity of the reservoir, giving us more confidence that we have separated the scattered signal from simple formation reflectivity. Variation of the scattered energy along the image planes suggests variability in the quality of the fractures in three distinct zones.
Mark E. Willis; Daniel R. Burns; M. Nafi Toksoz
Geothermal: Sponsored by OSTI -- Injection through fractures
Office of Scientific and Technical Information (OSTI)
Injection through fractures Geothermal Technologies Legacy Collection HelpFAQ | Site Map | Contact Us | Admin Log On HomeBasic Search About Publications Advanced Search New Hot...
Fatigue and Fracture I - Programmaster.org
Science Conference Proceedings (OSTI)
Oct 10, 2012 ... Fretting Corrosion Induced Fracture of a Floating Bearing Base Plate in a 250 Tons Yankee Paper Drum: Pierre Dupont1; 1Schaeffler Belgium�...
Naturally fractured tight gas reservoir detection optimization
Research continued on methods to detect naturally fractured tight gas reservoirs. This report discusses 3D-3C seismic acquisition and 3D P-wave alternate processing.
Microseismic Tracer Particles for Hydraulic Fracturing
NLE Websites -- All DOE Office Websites (Extended Search)
The trend toward production of hydrocarbons from unconventional reservoirs (tight gas, shale oilgas) has caused a large increase in the use of hydraulic fracture stimulation of...
Hydraulic fracturing and shale gas extraction.
??In the past decade the technique of horizontal drilling and hydraulic fracturing has been improved so much that it has become a cost effective method� (more)
Klein, Michael
Geothermal: Sponsored by OSTI -- Hydraulic fracturing: insights...
Office of Scientific and Technical Information (OSTI)
Hydraulic fracturing: insights from field, lab, and numerical studies Geothermal Technologies Legacy Collection HelpFAQ | Site Map | Contact Us | Admin Log On HomeBasic Search...
MML Leads Discussion of Dynamic Fracture Testing
Science Conference Proceedings (OSTI)
Dynamic Fracture in Steel. ... More recently, the pipeline industry has been adopting the CTOA ... fatigue characteristics of new pipeline steels, as these ...
Molecular Dynamics Simulation of Thermoset Fracture with ...
Science Conference Proceedings (OSTI)
The effects of resin chain extensibility and dilution on fracture behavior are studied by testing a variety of molecular systems. The molecular bases for precursors�...
Fracture of Thin Films and Nanomaterials
Science Conference Proceedings (OSTI)
Mar 4, 2013 ... Fracture Toughness of SPD-Deformed Nanostructured Rail Steels and Its Implications on the In-Service Behaviour: Christoph Kammerhofer1;�...
Deformation and Fracture - Programmaster.org
Science Conference Proceedings (OSTI)
Mar 14, 2012 ... Investigations on the crack propagation resistance showed an increasing fracture resistance with crack extension, so-called R-curve behavior.
Hydraulic fractures traced by monitoring microseismic events
NLE Websites -- All DOE Office Websites (Extended Search)
Summary: The trend toward production of hydrocarbons from unconventional reservoirs (tight gas, shale oilgas) has caused a large increase in the use of hydraulic fracture...
Structural Settings Of Hydrothermal Outflow- Fracture Permeability...
elevated stress termed breakdown regions. Here, stress concentrations cause active fracturing and continual re-opening of fluid-flow conduits, permitting long-lived hydrothermal...
Enhancing in situ bioremediation with pneumatic fracturing
Science Conference Proceedings (OSTI)
A major technical obstacle affecting the application of in situ bioremediation is the effective distribution of nutrients to the subsurface media. Pneumatic fracturing can increase the permeability of subsurface formations through the injection of high pressure air to create horizontal fracture planes, thus enhancing macro-scale mass-transfer processes. Pneumatic fracturing technology was demonstrated at two field sites at Tinker Air Force Base, Oklahoma City, Oklahoma. Tests were performed to increase the permeability for more effective bioventing, and evaluated the potential to increase permeability and recovery of free product in low permeability soils consisting of fine grain silts, clays, and sedimentary rock. Pneumatic fracturing significantly improved formation permeability by enhancing secondary permeability and by promoting removal of excess soil moisture from the unsaturated zone. Postfracture airflows were 500% to 1,700% higher than prefracture airflows for specific fractured intervals in the formation. This corresponds to an average prefracturing permeability of 0.017 Darcy, increasing to an average of 0.32 Darcy after fracturing. Pneumatic fracturing also increased free-product recovery rates of number 2 fuel from an average of 587 L (155 gal) per month before fracturing to 1,647 L (435 gal) per month after fracturing.
Anderson, D.B.; Peyton, B.M.; Liskowitz, J.L.; Fitzgerald, C.; Schuring, J.R.
Performance Analysis & Optimization of Well Production in Unconventional Resource Plays
The Unconventional Resource Plays consisting of the lowest tier of resources (large volumes and most difficult to develop) have been the main focus of US domestic activity during recent times. Horizontal well drilling and hydraulic fracturing completion technology have been primarily responsible for this paradigm shift. The concept of drainage volume is being examined using pressure diffusion along streamlines. We use diffusive time of flight to optimize the number of hydraulic fracture stages in horizontal well application for Tight Gas reservoirs. Numerous field case histories are available in literature for optimizing number of hydraulic fracture stages, although the conclusions are case specific. In contrast, a general method is being presented that can be used to augment field experiments necessary to optimize the number of hydraulic fracture stages. The optimization results for the tight gas example are in line with the results from economic analysis. The fluid flow simulation for Naturally Fractured Reservoirs (NFR) is performed by Dual-Permeability or Dual-Porosity formulations. Microseismic data from Barnett Shale well is used to characterize the hydraulic fracture geometry. Sensitivity analysis, uncertainty assessment, manual & computer assisted history matching are integrated to develop a comprehensive workflow for building reliable reservoir simulation models. We demonstrate that incorporating proper physics of flow is the first step in building reliable reservoir simulation models. Lack of proper physics often leads to unreasonable reservoir parameter estimates. The workflow demonstrates reduced non-uniqueness for the inverse history matching problem. The behavior of near-critical fluids in Liquid Rich Shale plays defies the production behavior observed in conventional reservoir systems. In conventional reservoirs an increased gas-oil ratio is observed as flowing bottom-hole pressure is less than the saturation pressure. The production behavior is examined by building a compositional simulation model on an Eagle Ford well. Extremely high pressure drop along the multiple transverse hydraulic fractures and high critical gas saturation are responsible for this production behavior. Integrating pore-scale flow modeling (such as Lattice Boltzmann) to the field-scale reservoir simulation may enable quantifying the effects of high capillary pressure and phase behavior alteration due to confinement in the nano-pore system.
Sehbi, Baljit Singh
??This is the first academic study of well costs and drilling times for Australia?s petroleum producing basins, both onshore and offshore. I analyse a substantial� (more)
Leamon, Gregory Robert
Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks
Science Conference Proceedings (OSTI)
Hydraulic fracturing has been used widely to stimulate production of oil, natural gas, and geothermal energy in formations with low natural permeability. Numerical optimization of fracture stimulation often requires a large number of evaluations of objective ... Keywords: Fractal dimension, Global sensitivity, Hydraulic fracturing, Optimization, Surrogate model
Mingjie Chen, Yunwei Sun, Pengcheng Fu, Charles R. Carrigan, Zhiming Lu, Charles H. Tong, Thomas A. Buscheck
Effects of alkali-metal impurities on fracture toughness of 2090 Al-Li-Cu extrusions
Science Conference Proceedings (OSTI)
The effects of alkali-metal impurity (AMI) content, temperature, and crack-mouth-opening displacement (CMOD) rate on the fracture toughness of 2090-T8 Al-Li-Cu alloy extrusions were studied, particularly for short-transverse (S-L) orientations. Decreasing AMI content resulted in increasing room-temperature fracture toughness, especially for underaged S-L and T-L specimens. Unlike most Al-Li based alloys, material with very low (AMIs produced by vacuum refining had a high S-L fracture toughness (up to 38 MPa{radical}m for proof strengths {approximately}440 MPa) as well as high toughness in other orientations. The increase in room-temperature fracture toughness with decreasing AMI content was associated with a decrease in the proportion o brittle intergranular and cleavage-like islands, and a corresponding increase in the proportion of high energy dimpled fracture modes, on fracture surfaces. Both the present and previous studies indicate that the brittle islands result from liquid-metal embrittlement due to the presence of discrete sodium-potassium rich liquid phases. For medium to high AMI contents (5 to 37 wt ppm), S-L fracture toughness increased with decreasing temperature due to solidification of these phases and a consequent decrease in the mobility of embrittling atoms. The ability of embrittling atoms to keep up with crack tips also depended on crack velocity so that CMOD rate influenced fracture toughness. The grain structure (degree of recrystallization) appeared to be another important parameter affecting fracture toughness.
Sweet, E.D.; Bennett, C.G.; Musulin, I. [Comalco Research Centre, Thomastown, Victoria (Australia); Lynch, S.P.; Nethercott, R.B. [Defence Science and Technology Organisation, Melbourne, Victoria (Australia)
Ductile fracture modeling : theory, experimental investigation and numerical verification
The fracture initiation in ductile materials is governed by the damaging process along the plastic loading path. A new damage plasticity model for ductile fracture is proposed. Experimental results show that fracture ...
Xue, Liang, 1973-
Simulation of Fluid Flow in Fractured Porous Media, Watergovern fluid flow in fractured porous media. These are (i)for Modeling Fluid and Heat Flow in fractured Porous Media,
Pruess, K.
Fracture orientation analysis by the solid earth tidal strain method | Open
orientation analysis by the solid earth tidal strain method orientation analysis by the solid earth tidal strain method Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Fracture orientation analysis by the solid earth tidal strain method Details Activities (1) Areas (1) Regions (0) Abstract: A new practical method has been developed to estimate subsurface fracture orientation based on an analysis of solid earth tidal strains. The tidal strain fracture orientation technique is a passive method which has no depth limitation. The orientation of either natural or hydraulically stimulated fractures can be measured using either new or old static observation wells. Estimates for total compressibility and areal interconnected porosity can also be developed for reservoirs with matrix permeability using a combination of tidal and barometric strain analysis.
On the multiscale origins of fracture resistance in human bone and its biological degradation
Akin to other mineralized tissues, human cortical bone can resist deformation and fracture due to the nature of its hierarchical structure, which spans the molecular to macroscopic length-scales. Deformation at the smallest scales, mainly through the composite action of the mineral and collagen, contributes to bone?s strength or intrinsic fracture resistance, while crack-tip shielding mechanisms active on the microstructural scale contribute to the extrinsic fracture resistance once cracking begins. The efficiency with which these structural features can resist fracture at both small and large length-scales becomes severely degraded with such factors as aging, irradiation and disease. Indeed aging and irradiation can cause changes to the cross-link profile at fibrillar length-scales as well as changes at the three orders of magnitude larger scale of the osteonal structures, both of which combine to inhibit the bone's overall resistance to the initiation and growth of cracks.
Zimmermann, Elizabeth A.; Barth, Holly D.; Ritchie, Robert O.
A study of the dynamic fluid loss of hydraulic fracturing fluids under realistic shear conditions is presented. During a hydraulic fracturing treatment, a polymeric solution is pumped under pressure down the well to create and propagate a fracture. Part of the fluid leaks into the rock formation, leaving a skin layer of polymer or polymer filter cake, at the rock surface or in the pore space. This study focuses on the effects of shear rate and permeability on dynamic fluid-loss behavior of crosslinked and linear fracturing gels. Previous studies of dynamic fluid loss have mainly been with low-permeability cores and constant shear rates. Here, the effect of shear history and fluid-loss additive on the dynamic leakoff of high-permeability cores is examined.
Navarrete, R.C.; Cawiezel, K.E.; Constien, V.G. [Dowell Schlumberger, Tulsa, OK (United States)
Correlation of microstructure and fracture toughness in three high-speed steel rolls
The objective of this study is to clarify the fracture characteristics of high-speed steel (HSS) rolls in terms of microstructural factors such as matrix phase and primary carbide particles. Three HSS rolls with different chromium contents were fabricated by centrifugal casting, and the effect of the chromium addition was investigated through microstructural analysis, fracture-mechanism study, and toughness measurement. The hard and brittle primary carbides, as well as the eutectic carbides (ledeburites), were segregated in the intercellular regions and dominated overall properties. Observation of the fracture process revealed that these primary carbides cleaved first to form microcracks at low stress-intensity factor levels and that the microcracks then readily propagated along the intercellular networks. The addition of chromium to a certain level yielded microstructural modification, including the homogeneous distribution of primary carbides, thereby leading to enhancement of fracture toughness of the HSS rolls.
Lee, S.; Sohn, K.S.; Lee, C.G. [Pohang Univ. of Science and Technology (Korea, Republic of). Center for Advanced Aerospace Materials; Jung, B.I. [Kangwon Industries, Ltd., Pohang (Korea, Republic of). Roll Technology Dept.
Uncertainty analysis of well test data
During a well test a transient pressure response is created by a temporary change in production rate. The well response is usually monitored during a relatively short period of time, depending upon the test objectives. Reservoir properties are determined from well test data via an inverse problem approach. Uncertainty is inherent in any nonlinear inverse problem. Unfortunately, well test interpretation suffers particularly from a variety of uncertainties that, when combined, reduce the confidence that can be associated with the estimated reservoir properties. The specific factors that have been analyzed in this work are: 1. Pressure noise (random noise) 2. Pressure drift (systematic variation) 3. Rate history effects Our work is based on the analysis of the effects of random pressure noise, the drift error, and the rate history on the estimation of typical reservoir parameters for two common reservoir models: A vertical well with a constant wellbore storage and skin in a homogeneous reservoir. A vertical well with a finite conductivity vertical fracture including wellbore effects in a homogeneous reservoir. This work represents a sensitivity study of the impact of pressure and rate uncertainty on parameter estimation and the confidence intervals associated with these results. In this work we statistically analyze the calculated reservoir parameters to quantify the impact of pressure and rate uncertainty on them.
Merad, Mohamed Belgacem
Well completion and operations for MHF of Fenton Hill HDR Well EE-2
Previous attempts to connect Fenton Hill Hot Dry Rock Geothermal Site Wells EE-2 and EE-3 by pumping 150 thousand to 1.3 million gallons of water had not achieved a detectable hydraulic fracture connection. Therefore, preparations were made to conduct, in December 1983, a 4 to 6 million gallon, 50 BPM water injection in EE-2. The objective was to enlarge the previously created reservoir in EE-2 using massive hydraulic facturing (MHF). The planning, preparations, operations and results of the MHF are presented here. 4 refs., 7 figs.
Dreesen, D.S.; Nicholson, R.W.
BOREHOLE PRECONDITIONING OF GEOTHERMAL WELLS FOR ENHANCED GEOTHERMAL SYSTEM BOREHOLE PRECONDITIONING OF GEOTHERMAL WELLS FOR ENHANCED GEOTHERMAL SYSTEM RESERVOIR DEVELOPMENT Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: BOREHOLE PRECONDITIONING OF GEOTHERMAL WELLS FOR ENHANCED GEOTHERMAL SYSTEM RESERVOIR DEVELOPMENT Details Activities (1) Areas (1) Regions (0) Abstract: Thermal stimulation can be utilized to precondition a well to optimize fracturing and production during Enhanced Geothermal System (EGS) reservoir development. A finite element model was developed for the fully coupled processes consisting of: thermoporoelastic deformation, hydraulic conduction, thermal osmosis, heat conduction, pressure thermal effect, and the interconvertibility of mechanical and thermal energy. The model has
All available data on proppants and fluids were examined to determine areas in technology that need development for 300 to 500/sup 0/F (150/sup 0/ to 265/sup 0/C) hydrothermal wells. While fluid properties have been examined well into the 450/sup 0/F range, proppants have not been previously tested at elevated temperatures except in a few instances. The latest test data at geothermal temperatures is presented and some possible proppants and fluid systems that can be used are shown. Also discussed are alternative stimulation techniques for geothermal wells.
Sinclair, A.R.; Pittard, F.J.; Hanold, R.J.
The Effect of Well Trajectory on Production Performance of Tight Gas Wells
Horizontal wells are a very important element in oil and gas industry due to their distinguished advantages. Horizontal wells are not technically horizontal. This is because of the structural nature of reservoir formations and drilling procedures. In response to the reservoir rock�s strength, the horizontal well deviates upward and downward while being drilled forming an undulating path instead of a horizontal. In this study, horizontal wells with an undulating trajectory within a gas reservoir have been studied. The aim of this research is to investigate the effect of the trajectory angle on pressure drop in horizontal wells. In addition, the contribution of water flow to pressure drop is a part of this research. Generally, water comes from different sources like an aquifer or a water flood job. In low permeability horizontal wells, hydraulic fracturing introduces water to gas wells. Water distribution is an important issue in gas wells production. In order to achieve the goal of this study, a model has been developed to simulate different situations for a horizontal well with an undulating trajectory in gas reservoirs. This study is a step forward to understand well performance in low permeability gas reservoirs.
Aldousari, Mohammad
Shock chlorination is a method of disinfecting a water well. This publication gives complete instructions for chlorinating with bleach or with dry chlorine. It is also available in Spanish as publication L-5441S
McFarland, Mark L.; Dozier, Monty
Texas earthquakes may be linked to wells for gas mining By Dan Vergano, USA TODAY
Texas earthquakes may be linked to wells for gas mining By Dan Vergano, USA TODAY -- Saltwater study. "We usually only get small ones." Some suspicions centered on wells involved in "hydraulic. About 13 fracture wells have been drilled since 2002 near the locale, but the team found the epicenter
Huang, Shaopeng
injection and hydraulic fracturing stress measurements inlevel measured with hydraulic fracturing (reproduced from
Rutqvist, J.
Optimization of Construction Discharge Rate and Proppant Slugs for Preventing Complex Fractures
Science Conference Proceedings (OSTI)
For volcanic rock and fracture type reservoir, etc, steering fractures, branching fractures and their combined herringbone fractures are usually caused by hydraulic fracturing. The generation of these complex fractures is one of the crucial factors that ... Keywords: hydraulic fracturing, construction discharge rate, complex fractures, proppant slug, optimization
Dali Guo; Yang Lin; Yong Ji; Jiangwen Xu; Guobin Wang
A method of measuring a parameter in a well, under isobaric conditions, including such parameters as hydraulic gradient, pressure, water level, soil moisture content and/or aquifer properties the method as presented comprising providing a casing having first and second opposite ends, and a length between the ends, the casing supporting a transducer having a reference port; placing the casing lengthwise into the well, second end first, with the reference port vented above the water table in the well; and sealing the first end. A system is presented for measuring a parameter in a well, the system comprising a casing having first and second opposite ends, and a length between the ends and being configured to be placed lengthwise into a well second end first; a transducer, the transducer having a reference port, the reference port being vented in the well above the water table, the casing being screened across and above the water table; and a sealing member sealing the first end. In one embodiment, the transducer is a tensiometer transducer and in other described embodiments, another type transducer is used in addition to a tensiometer.
Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)
Finding Large Aperture Fractures in Geothermal Resource Areas...
low-permeability fractures and LAF's (Large Aperature Fractures). USG will develop and test the combination of three-component,long-offset seismic surveying, permanent scatter...
Characterizing Fractures in Geysers Geothermal Field by Micro...
water through existing fractures into hot wet and hot dry rocks by thermo-elastic cooling shrinkage. The stimulated, existing fractures thus enhance the permeability of the...
Modeling Of Hydraulic Fracture Network Propagation In Shale Gas Reservoirs.
??The most effective method for stimulating shale gas reservoirs is massive hydraulic fracture treatments. Recent fracture diagnostic technologies such as microseismic technology have shown that� (more)
Ahn, Chong
Irradiation Effects on Human Cortical Bone Fracture Behavior
NLE Websites -- All DOE Office Websites (Extended Search)
Irradiation Effects on Human Cortical Bone Fracture Behavior Print Human bone is strong but still fallible. To better predict fracturing in bone, researchers need a mechanistic...
An Alternate Approach for Characterizing the Fracture Resistance of ...
Science Conference Proceedings (OSTI)
While the elastic properties and strength of fish scales have received considerable attention, the resistance to fracture has not. Here the fracture resistance of�...
Microseismicity, stress, and fracture in the Coso geothermal...
Microearthquakes in the geothermal field are proposed as indicators of shear fracturing associated with fluid injection and circulation along major pre-existing fractures....
A physical model for fracture surface features in metallic glasses
Science Conference Proceedings (OSTI)
Apr 30, 2010 ... at a rate of 1000 mm/ min, fracturing the grease in the sample. Photographs were then taken of the fracture surfaces. The photographs were�...
Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.
Thermal depletion of a geothermal reservoir with both fracture and pore permeability
A method for estimating the useful lifetime of a reservoir in porous rock where the injection and production wells intersect a fracture system is presented. Equations were derived for the pore-fluid and fracture-fluid temperatures averaged over large regions of the geothermal field. Problems such as incomplete areal sweep and interfingering of cool and hot fluids are ignored. Approximate equations relating average temperatures to the heat flowing from rock to fluid were developed, and their use is justified by comparing the results with solutions of the exact equations. The equations for the temperature decline can be solved quickly. In the model, fractures are characterized by three parameters: aperture w, permeability k/sub fr/, and spacings between fractures D. For certain values of these parameters, cool reinjected fluid in fractures may reach the production wells long before all the warm pore fluid has been tapped, shortening the useful lifetime of the field. The traditional (and important) problems of reservoir engineering, flow rate determination, drawdown, sweep patterns, etc. were ignored. Thus the results are most useful in providing a correction factor which can be applied to lifetime estimates obtained from a detailed simulation of a field assuming porous rock. That correction factor is plotted for clean fractures (k/sub fr/ = w/sup 2//12) as a function of w and D for several lifetime ranges. Small-scale fractures seen in cores from the Salton Sea Geothermal Field are too closely spaced to reduce lifetime estimates. However, large-scale fault systems exist within that field, and they are attractive drilling targets because they produce large flow rates. If large scale faults communicate between injection and production wells, they may reduce the useful lifetime of those wells.
Kasameyer, P.W.; Schroeder, R.C.
Occult fractures of the knee: tomographic evaluation
Seven adults with painful effusions of the knee were examined for occult fractures using pluridirectional tomograph in the coronal and lateral planes. Six patients (ages 50 to 82 years) were osteopenic and gave histories ranging from none to mild trauma; one 26-year-old man was not osteopenic and had severe trauma. In all cases, routine radiographs were interpreted as negative, but tomography demonstrated a fracture. Five fractures were subchondral. Bone scans in 2 patients were positive. The authors conclude that osteopenic patients with a painful effusion of the knee should be considered to have an occult fracture. While bone scans may be helpful, tomography is recommended as the procedure of choice to define the location and extent of the fracture.
Apple, J.S.; Martinez, S.; Allen, N.B.; Caldwell, D.S.; Rice, J.R.