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Office of Scientific and Technical Information
Multi-offset vertical seismic profiles: fracture and fault identification for Appalachian basin reservoirs - two case examples
SciTech Connect
Many Appalachian basin reservoirs occur in older rocks that are commonly fractured and faulted. These fractures and faults very often act as the reservoir trapping mechanism, especially in lithologies with no log-detectable matrix porosity. Traditional logging techniques, although possibly showing fault or fracture presence in the well bore, seldom provide clues to the extent of fracturing or location of nearby faults. Surface seismic data should show faults and perhaps even fracturing, but showing these features is often not possible in rugged terrain or in areas with thick coverings of unconsolidated surface material. Traditional seismic also has resolutions lower than that needed to detect small faults (less than 70 ft). Two case examples are shown from the northern Appalachian basin. The first example utilizes Schlumberger's slim hole seismic tool in cased holes in an area of thick unconsolidated glacial material along the Bass Island trend of western New York. The second example utilizes Schlumberger's SAT tool in an open-hole environment in an area of northwestern Pennsylvania with disturbed surface bedding and poor conventional surface seismic returns. The slim hole tool provides good data but with only slightly greater resolution than surface Vibroseis data. The SAT tool provides excellent resolution (down to 25 ft) in highly disturbed bedding.
Wyatt, D.E.; Bennett, B.A.; Walsh, J.J.
Hydraulic Fracture Optimization with a Pseudo-3D Model in Multi-layered Lithology
E-Print Network (OSTI)
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
The effect of fractures, faults, and sheared shale zones on the hydrology of Bear Creek Burial Grounds A-South, Oak Ridge, Tennessee
Previous hydrologic models of flow in Bear Creek Valley have presented lateral flow as occurring through the Nolichucky Shale in parallel to strike fractures within thin carbonate beds; the effects of faults were not considered. This study presents a ground water flow model that incorporates lateral flow through parallel-to-strike fractures and thrust faults, and perpendicular-to-strike cross valley strike-slip faults. These latter cross-valley structures cause flow to be diverted to other strikeparallel zones of enhanced permeability towards the south side of the valley. Using core, geophysical and hydrologic data from five boreholes in the Bear Creek Burial Grounds three types of potential fluid-flow conduits were identified: fractures, faults, and shale shear zones. Open fractures decrease in abundance with depth and tend to occur most frequently in oolitic limestone beds relative to other carbonate lithologies. Fractures below 1 00 ft BGS in the Nolichucky Shale and below 250 ft in the Maynardville Limestone do not appear to be caused by dissolution; instead, they appear to be the result of a change in the local stress field due to erosion effects. Faults, both cross-valley and thrust faults, and sheared shale zones are interpreted to disrupt the lateral continuity of the bedding and increase the rock-mass permeability of the Nolichucky Shale, permitting ground water to flow these structural zones. This study provided opportunity to interpret DNAPL migration patterns from Burial Ground A-South. DNAPL migration parallel to the valley's axis is affected by parallel-to-strike fractures and thrust faults, and its lateral migration perpendicular to strike is influenced by cross valley strike-slip faults and decreasing collect at depth because of decreasing fracture occurrence and reduced permeability and then migrate laterally along the cross valley strike-slip faults until it encounters and enters a zone of higher permeability parallel to strike.
Hollon, Dwight Mitchell
Surface and subsurface fault and fracture systems with associated natural gas production in the Lower Mississippian and Upper Devonian, Price Formation, southern West Virginia.
??Production from natural gas deposits is often enhanced by fault and fracture systems associated with reservoirs. This study presents analyses of fault and fracture systems� (more)
Johnson, S. Reed.
Faulting, fracturing, and sealing in foreland thrust belts: Examples from the subalpine chains
The hydrocarbon potential of foreland thrust belts arises from source and reservoir rocks juxtaposed by the movement of thrust sheets, promoting maturation by loading and generating structural traps. Deformation in thrust belts can be localized on fault zones or distributed throughout thrust sheets; different deformation mechanisms operate to increase and decrease permeability. Migration and reservoir properties may be enhanced or reduced by faulting and fault-related deformation. These processes are examined in detail using examples from the northwest subalpine chains of France, a fold-and-thrust belt of well-differentiated Mesozoic shales and carbonates. Seeps of bitumen in foreland basin sediments indicate some migration of hydrocarbons along faults linking probable source and reservoir areas. Detailed examination of fault rocks and thrust sheets shows that fracture formation is an important strain mechanism which has the potential to form regions of enhanced permeability in structures such as hanging wall anticlines. However, the fractures observed are in general recemented, forming with crack-seal crystal growth. The faults themselves are complex zones up to tens of meters thick of subparallel anastomosing gouge, fractures, stylolites, and crystalline calcite, indicating synchronous cataclasis and pressure solution. The range of scales of fracturing suggests stick-slip (microseismic) fault activity. Permeability of the fault zones is enhanced during seismic fault slip and is otherwise steadily decreased by pressure solution and calcite deposition. The available migration pathways, and hence the location of potential reservoirs, is controlled by the timing, mechanisms, and extent of fault activity in this common and productive tectonic regime.
Bowler, S.; Butler, R.W.H.
Intrusion Margins and Associated Fractures | Open Energy Information
Open Energy Info (EERE)
Intrusion Margins and Associated Fractures Intrusion Margins and Associated Fractures Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Print PDF Intrusion Margins and Associated Fractures Dictionary.png Intrusion Margins and Associated Fractures: No definition has been provided for this term. Add a Definition Controlling Structures List of controlling structures typically associated with geothermal systems: Major Normal Fault Termination of a Major Normal Fault Stepover or Relay Ramp in Normal Fault Zones Apex or Salient of Normal Fault Fault Intersection Accommodation Zone Displacement Transfer Zone Pull-Apart in Strike-Slip Fault Zone Intrusion Margins and Associated Fractures Stratigraphic Boundaries Fissure Swarms Caldera Rim Margins Lithologically Controlled Fractures caused by igneous activity creates permeability, allowing water
Mechanical properties and modeling of seal-forming lithologies
Science Conference Proceedings (OSTI)
The goal of this research is to evaluate the roles of deformation and the occurrence of weak sedimentary lithologies subjected to gravitational loads in shaping conventional and unconventional oil and gas reservoirs. Two sedimentary lithologies that influence the geometries, physical properties, and heterogeneities of oil and gas reservoirs are shale and rocksalt. Both form effect barriers to the flow and communication of petroleum and gas and, in many cases, form the seals to major reservoirs due to their low permeabilities. Both are actively deformed in depositional environments due to their low strengths relative to gravitational loads applied. Thus, the shapes of seal-forming units, and the nature of fractures and faults that may breach them depend upon either the mechanical properties of shale or those of salt, and the loading histories to which they have been subjected. Deformed shales may, in addition, serve as unconventional reservoirs of gas if open fractures within them provide sufficient porosity. The fracture and flow properties of shales are not well constrained, and the authors are currently investigating these properties experimentally. The rheology of rocksalt, on the other hand, is well known and they believe that the time is right to apply the experimentally constrained constitutive relations for rocksalt to deformations in the Earth. Efforts are continuing on modeling fracture anisotropy and the authors have examined simple, two-mica models to evaluate the mechanical interactions they proposed for gneiss and mica-poor schists. Brief summaries of the progress and results to date for (1) the mechanical properties of schist, (2) a two-mica model of fracture anisotropy, (3) deformation of shale, and (4) modeling of salt and shale tectonics of the northern Gulf of Mexico are given in the following sections. 35 refs., 33 figs., 1 tab.
Kronenberg, A.K.; Russell, J.E.; Carter, N.L.; Mazariegos, R.; Shea, W.T.
Insights From Laboratory Experiments On Simulated Faults With Application To Fracture Evolution In Geothermal Systems
Laboratory experiments provide a wealth of information related to mechanics of fracture initiation, fracture propagation processes, factors influencing fault strength, and spatio-temporal evolution of fracture properties. Much of the existing literature reports on laboratory studies involving a coupling of thermal, hydraulic, mechanical, and/or chemical processes. As these processes operate within subsurface environments exploited for their energy resource, laboratory results provide insights into factors influencing the mechanical and hydraulic properties of geothermal systems. I report on laboratory observations of strength and fluid transport properties during deformation of simulated faults. The results show systematic trends that vary with stress state, deformation rate, thermal conditions, fluid content, and rock composition. When related to geophysical and geologic measurements obtained from engineered geothermal systems (e.g. microseismicity, wellbore studies, tracer analysis), laboratory results provide a means by which the evolving thermal reservoir can be interpreted in terms of physico-chemical processes. For example, estimates of energy release and microearthquake locations from seismic moment tensor analysis can be related to strength variations observed from friction experiments. Such correlations between laboratory and field data allow for better interpretations about the evolving mechanical and fluid transport properties in the geothermal reservoir � ultimately leading to improvements in managing the resource.
Stephen L. Karner, Ph.D
Integrating complementarity into the 2D displacement discontinuity boundary element method to model faults and fractures with frictional contact properties
We present a two-dimensional displacement discontinuity method (DDM) in combination with a complementarity solver to simulate quasi-static slip on cracks as models for faults and fractures in an otherwise homogeneous, isotropic, linear elastic material. ... Keywords: Boundary element model, Complementarity, Friction, Frictional strength
Elizabeth Ritz; Ovunc Mutlu; David D. Pollard
: INSIGHTS FROM THE BOWIE COAL MINES, SOUTHERN PICEANCE BASIN, WESTERN COLORADO by Eric D. Robeck A thesis-INDUCED STRESS ANISOTROPY ON FRACTURING, FOLDING AND SILL EMPLACEMENT: INSIGHTS FROM THE BOWIE COAL MINES. The Bowie underground coal mines of western Colorado expose a reverse-reactivated growth fault
Seamons, Kent E.
Lithology, fault displacement, and origin of secondary calcium carbonate and opaline silica at Trenches 14 and 14D on the Bow Ridge Fault at Exile Hill, Nye County, Nevada
Yucca Mountain, a proposed site for a high-level nuclear-waste repository, is located in southern Nevada, 20 km east of Beatty, and adjacent to the southwest comer of the Nevada Test Site (NTS) (fig. 1). Yucca Mountain is located within the Basin and Range province of the western United States. The climate is semiarid, and the flora is transitional between that of the Mojave Desert to the south and the Great Basin Desert to the north. As part of the evaluation, hydrologic conditions, especially water levels, of Yucca Mountain and vicinity during the Quaternary, and especially the past 20,000 years, are being characterized. In 1982, the US Geological Survey, in cooperation with the US Department of Energy (under interagency agreement DE-A104-78ET44802), excavated twenty-six bulldozer and backhoe trenches in the Yucca Mountain region to evaluate the nature and frequency of Quaternary faulting (Swadley and others, 1984). The trenches were oriented perpendicular to traces of suspected Quaternary faults and across projections of known bedrock faults into Quaternary deposits. Trench 14 exposes the Bow Ridge Fault on the west side of Exile Hill. Although the original purpose of the excavation of trench 14 was to evaluate the nature and frequency of Quaternary faulting on the Bow Ridge Fault, concern arose as to whether or not the nearly vertical calcium carbonate (the term ``carbonate`` in this study refers to calcium carbonate) and opaline silica veins in the fault zone were deposited by ascending waters (ground water). These veins resemble in gross morphology veins commonly formed by hydrothermal processes.
Taylor, E.M.; Huckins, H.E.
Property:LithologyInfo | Open Energy Information
LithologyInfo LithologyInfo Jump to: navigation, search Property Name LithologyInfo Property Type Text Subproperties This property has the following 93 subproperties: 2 2-M Probe Survey A Active Seismic Methods Active Sensors Aerial Photography Aeromagnetic Survey Analytical Modeling C Caliper Log Cation Geothermometers Cement Bond Log Chemical Logging Compound and Elemental Analysis Conceptual Model Controlled Source Frequency-Domain Magnetics Cross-Dipole Acoustic Log D Data Acquisition-Manipulation Data Collection and Mapping Data Techniques Data and Modeling Techniques Drilling Methods E Electric Micro Imager Log Electromagnetic Sounding Methods Elemental Analysis with Fluid Inclusion F FLIR Fault Mapping Field Techniques Flow Test Fluid Inclusion Analysis Fluid Lab Analysis Formation Testing Techniques
Single fracture aperture patterns: Characterization by slit-island fractal analysis
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.
Natural gas exploration associated with fracture systems in Alleghenian thrust faults in the Greenbrier Formation, southern West Virginia.
??A hydrocarbon play of southern West Virginia targets the intersection of thrust faults with specific Mississippian reservoirs. Typical study area wells yield initial production rates� (more)
Edmonds, Craig A.
Tectonic Setting and Characteristics of Natural Fractures in Mesaverde and Dakota Reservoirs of the San Juan Basin, New Mexico and Colorado
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.
Fault Mapping | Open Energy Information
form form View 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 with form History Facebook icon Twitter icon » Fault Mapping Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Fault Mapping Details Activities (2) Areas (2) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Field Techniques Exploration Sub Group: Data Collection and Mapping Parent Exploration Technique: Data Collection and Mapping Information Provided by Technique Lithology: Stratigraphic/Structural: Locates active faults in the area of interest Hydrological: Can reveal whether faults are circulating hydrothermal fluids Thermal: Dictionary.png
Fault Intersection | Open Energy Information
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 » Fault Intersection Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Print PDF Fault Intersection Dictionary.png Fault Intersection: Fault intersections are junctions between normal faults and either transversely oriented strike-slip or oblique-slip faults. Subsurface fluid flow in these areas is enhanced by multiple minor faults that connect the major intersecting structures, forming highly fractured zones or dilational quadrants with increased permeability. Other definitions:Wikipedia Reegle Controlling Structures List of controlling structures typically associated with geothermal
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
Analysis of the growth of strike-slip faults using effective medium theory
Increases in the dimensions of strike-slip faults including fault length, thickness of fault rock and the surrounding damage zone collectively provide quantitative definition of fault growth and are commonly measured in terms of the maximum fault slip. The field observations indicate that a common mechanism for fault growth in the brittle upper crust is fault lengthening by linkage and coalescence of neighboring fault segments or strands, and fault rock-zone widening into highly fractured inner damage zone via cataclastic deformation. The most important underlying mechanical reason in both cases is prior weakening of the rocks surrounding a fault's core and between neighboring fault segments by faulting-related fractures. In this paper, using field observations together with effective medium models, we analyze the reduction in the effective elastic properties of rock in terms of density of the fault-related brittle fractures and fracture intersection angles controlled primarily by the splay angles. Fracture densities or equivalent fracture spacing values corresponding to the vanishing Young's, shear, and quasi-pure shear moduli were obtained by extrapolation from the calculated range of these parameters. The fracture densities or the equivalent spacing values obtained using this method compare well with the field data measured along scan lines across the faults in the study area. These findings should be helpful for a better understanding of the fracture density/spacing distribution around faults and the transition from discrete fracturing to cataclastic deformation associated with fault growth and the related instabilities.
Aydin, A.; Berryman, J.G.
A Handbook for the Application of Seismic Methods for Quantifying Naturally Fractured Gas Reservoirs in the San Juan Basin, New Mexico
Measured anisotropy in Pierre Shale: Geophys. Prosp. , 31,fractures embedded in sand-shale lithologies. The fractureto also correlate to the shale rich material and the greens
Application on lithology recognition with BP artificial neural network
An Artificial Neural Network (ANN) model is established to recognize the drilled formations' lithologies while drilling. The styles of output and input of ANN are designed. The nerve cells in input layer are weight of bit (WOB), speed of rotary (SOR) ... Keywords: artificial neural network, drilling, formation lithology, recognition
Jinhui Zhou; Jienian Yan; Li Pan
Property:HostRockLithology | Open Energy Information
HostRockLithology HostRockLithology Jump to: navigation, search Property Name HostRockLithology Property Type String Description Condensed description of the lithology of the reservoir rock. This is a property of type Page. Subproperties This property has the following 14 subproperties: B Beowawe Hot Springs Geothermal Area Brady Hot Springs Geothermal Area C Chena Geothermal Area D Desert Peak Geothermal Area G Geysers Geothermal Area H Heber Geothermal Area L Lightning Dock Geothermal Area R Raft River Geothermal Area Roosevelt Hot Springs Geothermal Area S Salton Sea Geothermal Area Steamboat Springs Geothermal Area S cont. Stillwater Geothermal Area V Valles Caldera - Sulphur Springs Geothermal Area W Wabuska Hot Springs Geothermal Area Pages using the property "HostRockLithology"
Property:CapRockLithology | Open Energy Information
CapRockLithology CapRockLithology Jump to: navigation, search Property Name CapRockLithology Property Type String Description Condensed description of the lithology of the cap rock. Subproperties This property has the following 6 subproperties: B Beowawe Hot Springs Geothermal Area Brady Hot Springs Geothermal Area D Desert Peak Geothermal Area E East Mesa Geothermal Area H Heber Geothermal Area S Salton Sea Geothermal Area Pages using the property "CapRockLithology" Showing 6 pages using this property. A Amedee Geothermal Area + volcanic; lacustrine sediments + B Blue Mountain Geothermal Area + Hydrothermal alteration layer + G Geysers Geothermal Area + Hydrothermal alteration layer + K Kilauea East Rift Geothermal Area + Overlapping a'a' and pahoehoe flows + L Long Valley Caldera Geothermal Area + Metasedimentary Landslide Block; Hydrothermal Alteration Layer +
Apex or Salient of Normal Fault | Open Energy Information
Apex or Salient of Normal Fault Apex or Salient of Normal Fault Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Print PDF Apex or Salient of Normal Fault Dictionary.png Apex or Salient of Normal Fault: Normal faults may intersect in the subsurface to form a fault apex or salient. Apices or salients of normal faults account for 3% of structural controls in the Great Basin. Other definitions:Wikipedia Reegle Controlling Structures List of controlling structures typically associated with geothermal systems: Major Normal Fault Termination of a Major Normal Fault Stepover or Relay Ramp in Normal Fault Zones Apex or Salient of Normal Fault Fault Intersection Accommodation Zone Displacement Transfer Zone Pull-Apart in Strike-Slip Fault Zone Intrusion Margins and Associated Fractures Stratigraphic Boundaries
The purpose of the study was to collect and analyze existing data on the Michigan Basin for fracture patterns on scales ranging form thin section to basin. The data acquisition phase has been successfully concluded with the compilation of several large digital databases containing nearly all the existing information on formation tops, lithology and hydrocarbon production over the entire Michigan Basin. These databases represent the cumulative result of over 80 years of drilling and exploration. Plotting and examination of these data show that contrary to most depictions, the Michigan Basin is in fact extensively faulted and fractured, particularly in the central portion of the basin. This is in contrast to most of the existing work on the Michigan Basin, which tends to show relatively simple structure with few or minor faults. It also appears that these fractures and faults control the Paleozoic sediment deposition, the subsequent hydrocarbon traps and very likely the regional dolomitization patterns. Recent work has revealed that a detailed fracture pattern exists in the interior of the Central Michigan Basin, which is related to the mid-continent gravity high. The inference is that early Precambrian, ({approx}1 Ga) rifting events presumed by many to account for the gravity anomaly subsequently controlled Paleozoic sedimentation and later hydrocarbon accumulation. There is a systematic relationship between the faults and a number of gas and oil reservoirs: major hydrocarbon accumulations consistently occur in small anticlines on the upthrown side of the faults. The main tools used in this study to map the fault/fracture patterns are detailed, close-interval (CI = 10 feet) contouring of the formation top picks accompanied by a new way of visualizing the data using a special color spectrum to bring out the third dimension. In addition, recent improvements in visualization and contouring software were instrumental in the study. Dolomitization is common in the Michigan Basin, and it is crucial in developing reservoir quality rocks in some fields. Data on the occurrence of dolomite was extracted from driller's reports for all reported occurrences in Michigan, nearly 50 fields and over 500 wells. A digital database was developed containing the geographic location of all these wells (latitude-longitude) as well as the elevation of the first encounter of dolomite in the field/reservoir. Analysis shows that these dolomite occurrences are largely confined to the center of the basin, but with some exceptions, such as N. Adams Field. Further, some of the dolomite occurrences show a definite relationship to the fracture pattern described above, suggesting a genetic relationship that needs further work. Other accomplishments of this past reporting period include obtaining a complete land grid for the State of Michigan and further processing of the high and medium resolution DEM files. We also have measured new fluid inclusion data on dolomites from several fields that suggest that the dolomitization occurred at temperatures between 100 and 150 C. Finally, we have extracted the lithologic data for about 5000 wells and are in the process of integrating this data into the overall model for the Michigan Basin.
James R. Wood; William B. Harrison
Fault finder
DOE Patents (OSTI)
A fault finder for locating faults along a high voltage electrical transmission line. Real time monitoring of background noise and improved filtering of input signals is used to identify the occurrence of a fault. A fault is detected at both a master and remote unit spaced along the line. A master clock synchronizes operation of a similar clock at the remote unit. Both units include modulator and demodulator circuits for transmission of clock signals and data. All data is received at the master unit for processing to determine an accurate fault distance calculation.
Bunch, Richard H. (1614 NW. 106th St., Vancouver, WA 98665)
Lithology and alteration mineralogy of reservoir rocks at Coso Geothermal
Lithology and alteration mineralogy of reservoir rocks at Coso Geothermal Lithology and alteration mineralogy of reservoir rocks at Coso Geothermal Area, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Lithology and alteration mineralogy of reservoir rocks at Coso Geothermal Area, California Details Activities (1) Areas (1) Regions (0) Abstract: Coso is one of several high-temperature geothermal systems associated with recent volcanic activity in the Basin and Range province. Chemical and fluid inclusion data demonstrate that production is from a narrow, asymmetric plume of thermal water that originates from a deep reservoir to the south and then flows laterally to the north. Geologic controls on the geometry of the upwelling plume were investigated using petrographic and analytical analyses of reservoir rock and vein material.
Internal structure of the Kern Canyon Fault, California: a deeply exhumed strike-slip fault
Deformation and mineral alteration adjacent to a 2 km long segment of the Kern Canyon fault near Lake Isabella, California are studied to characterize the internal structure of the fault zone and to understand the development of fault structure and constitution and the mechanical and chemical processes responsible for them. The 140 km long Kern Canyon fault (KCF) is a fault of 15 km right-lateral separation exhumed from seismogenic depth that cuts batholithic and metamorphic rocks of the southern Sierra Nevada. The fault consists of at least three distinct phases: an early phase of lower-greenschist-grade ductile shear with an S-C' phyllonite, a subsequent, dominant phase of brittle faulting characterized by a through-going zone of cataclastic rock, and a late stage of minor faulting along discontinuous, thin, hematitic gouge zones. The S-C' fabric and subsidiary fault-slip data indicate that both the phyllonitic and cataclastic zones are approximately vertical and strike-slip; slip lineations within the hematitic gouge suggest oblique-slip. The phyllonite zone trends N20-40E and accommodated ~175 m of separation. The cataclastic zone cuts the phyllonite, trends N21E, and consists of foliated and non-foliated cataclasites; it accommodates the majority of displacement along the fault. Abundant veins and fluid-assisted alteration in the rock surrounding the fault zone attest to the presence of fluids of evolving chemistry during both ductile and brittle faulting. Mass balance calculations indicate quartz loss during phyllonite faulting and imply that the fault system was open and experienced a negative change in volume during phyllonite faulting. Mesoscale and microscale fracture intensities decrease with log distance from the foliated cataclasites and approach a relatively low level at approximately 500 m. The internal structure of the Kern Canyon fault is similar to other large displacement faults in that it consists of a broad zone of fractured and altered rock and a narrow zone of intense cataclasis.
Neal, Leslie Ann
Stress and fault rock controls on fault zone hydrology, Coso geothermal
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 » Stress and fault rock controls on fault zone hydrology, Coso geothermal field, CA Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Stress and fault rock controls on fault zone hydrology, Coso geothermal field, CA Details Activities (1) Areas (1) Regions (0) Abstract: In crystalline rock of the Coso Geothermal Field, CA, fractures are the primary source of permeability. At reservoir depths, borehole image, temperature, and mud logs indicate fluid flow is concentrated in extensively fractured damage zones of large faults well-oriented for slip.
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.
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...
A core-based assessment of the spatial relationship of small faults associated with a basement-controlled, large normal fault in the Hickory Sandstone
This research characterized a system of small faults (displacement < 0.3 m) in seven closely-spaced continuous 2.4 inch (6.1 cm) diameter cores. Cores were obtained from central Texas, on the western edge of the Llano Uplift. Cores penetrate a dip-slip dominant, normal fault (Nobles Fault) with 18.3 m (60 ft) of stratigraphic throw. The spatial, geometric and kinematic attributes of small faults within the Nobles Fault system were characterized to explore potential cause-and-effect relationships. To quantify spatial distributions, a "density" measure based on individual small fault magnitude was utilized. Approximately half of the small faults in the core possessed no discernible offset markers; thus displacement amount for these faults could not be measured directly. Using a nonparametric method in which an alternating conditional expectation determined optimal transformations for the data, a statistically significant empirical correlation was established for faults with measurable gouge thickness, displacement, protolith mean grain size and sorting. Gouge thickness of small faults was found to be dependant upon the displacement amount of the small fault and the textural characteristics of the host protolith. The role of protolith lithology, proximity to crystalline basement, and structural position relative to the Nobles Fault system were examined to explain observed ubiquitous spatial distribution of small faults. Small faults were found to occur in clusters and the number of faults per foot only weakly correlates to the cumulative displacement of the corresponding faults. The amount of mudstone present is the dominant factor controlling small fault formation. Intervals with only minor quantities of mudstone have the largest number of faults per foot as well as largest associated cumulative displacement per foot. Frequency of occurrence of small faults near the basement is greater when compared to similar lithologies higher in the core. Intensity of small faults do not universally increase with proximity to large faults. To observe an increase in small faults, it is necessary to use a mean global cumulative displacement approach. Zones of greater than average cumulative displacement of small faults in close proximity to large faults were observed in zones that are compatible with faultfault interaction.
Graff, Mitchell C
Appendix A Lithologic and Monitor Well Completion Logs
Office of Legacy Management (LM)
A A Lithologic and Monitor Well Completion Logs This page intentionally left blank WELL INSTALLATION BLANK CASING: 1.25 in. Stainless Steel 0.0 to 0.35 METHOD WELL SCREEN: 1.25 in. Stainless Steel 0.35 to 3.27 DATE DEVELOPED SUMPIEND CAP: 1.25 in. Stainless Steel 3.27 to 3.58 WATER LEVEL (FT BGS) SURFACE SEAL: LOGGED BY P. McKenzie REMARKS Drillers hit water at 5 fl: well point removed. LITHOLOGIC DESCRIPTION LOCATION SHIPROCK, NM SURFACE ELEV. ( FT NGVD) 4890.00 SITE SHIPROCK TOP OF CASING (FT) 4890.00 WELL NUMBER 0602 MEAS. PT. ELEV. (FT) 4890.00 SLOT SIZE (IN) 0.125 WELL INSTALLATION INTERVAL (FT) DRILLING METHOD BLANK CASING: 1.25 in. Stainless Steel 0.0 to 0.35 METHOD WELL SCREEN: 1.25 in. Stainless Steel 0.35 to 3.27 DATE DEVELOPED SUMPIEND CAP: 1.25 in. Stainless Steel 3.27 to 3.58
Fracture analysis of the upper devonian antrim shale, Michigan basin
The Antrim Shale is a fractured, unconventional gas reservoir in the northern Michigan basin. Controls on gas production are poorly constrained but must depend on the fracture framework. Analyses of fracture geometry (orientation, spacing, and aperture width) were undertaken to better evaluate reservoir permeability and, hence, pathways for fluid migration. Measurements from nearly 600 fractures were made from outcrop, core, and Formation MicroScanner logs covering three members of the Antrim Shale (Norwood, Paxton, Lachine) and the Ellsworth Shale. Fracture analyses indicate pronounced reservoir anisotropy among the members. Together related with lithologic variations, this leads to unique reservoir characteristics within each member. There are two dominant fracture sets, northeast-southwest and northwest-southeast. Fracture density varies among stratigraphic intervals but always is lowest in the northwest-southeast fracture set and is greatest in the northeast-southwest fracture set. While aperture width decreases markedly with depth, subsurface variation in mean aperture width is significant. Based on fracture density and mean aperture width, the Norwood member has the largest intrinsic permeability and the Ellsworth Shale the lowest intrinsic permeability. The highest intrinsic fracture permeability in all intervals is associated with the northeast-southwest fracture set. The Norwood and Lachine members thus exhibit the best reservoir character. This information is useful in developing exploration strategies and completion practices in the Antrim Shale gas play.
Richards, J.A.; Budai, J.M.; Walter, L.M.; Abriola, L.M. (Univ. of Michigan, Ann Arbor, MI (United States))
Towards automatic lithological classification from remote sensing data using support vector machines
Remote sensing data can be effectively used as a means to build geological knowledge for poorly mapped terrains. In this study, the support vector machine (SVM) algorithm is applied to an automated lithological classification of a study area in northwestern ... Keywords: ASTER, Aeromagnetic, DEM, Lithological classification, Supervised classification, Support vector machine (SVM)
Le Yu; Alok Porwal; Eun-Jung Holden; Michael C. Dentith
Development of Characterization Technology for Fault Zone Hydrology
Several deep trenches were cut, and a number of geophysical surveys were conducted across the Wildcat Fault in the hills east of Berkeley, California. The Wildcat Fault is believed to be a strike-slip fault and a member of the Hayward Fault System, with over 10 km of displacement. So far, three boreholes of ~;; 150m deep have been core-drilled and borehole geophysical logs were conducted. The rocks are extensively sheared and fractured; gouges were observed at several depths and a thick cataclasitic zone was also observed. While confirming some earlier, published conclusions from shallow observations about Wildcat, some unexpected findings were encountered. Preliminary analysis indicates that Wildcat near the field site consists of multiple faults. The hydraulic test data suggest the dual properties of the hydrologic structure of the fault zone. A fourth borehole is planned to penetrate the main fault believed to lie in-between the holes. The main philosophy behind our approach for the hydrologic characterization of such a complex fractured system is to let the system take its own average and monitor a long term behavior instead of collecting a multitude of data at small length and time scales, or at a discrete fracture scale and to ?up-scale,? which is extremely tenuous.
Karasaki, Kenzi; Onishi, Tiemi; Gasperikova, Erika; Goto, Junichi; Tsuchi, Hiroyuki; Miwa, Tadashi; Ueta, Keiichi; Kiho, Kenzo; MIyakawa, Kimio
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
Reservoir-scale fracture permeability in the Dixie Valley, Nevada, geothermal field
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)
Fault and joint geometry at Raft River geothermal area, Idaho | Open Energy
and joint geometry at Raft River geothermal area, Idaho and joint geometry at Raft River geothermal area, Idaho Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Fault and joint geometry at Raft River geothermal area, Idaho Details Activities (1) Areas (1) Regions (0) Abstract: Raft River geothermal reservoir is formed by fractures in sedimentary strata of the Miocene and Pliocene Salt Lake Formation. The fracturing is most intense at the base of the Salt Lake Formation, along a decollement that dips eastward at less than 5 0 on top of metamorphosed Precambrian and Lower Paleozoic rocks. Core taken from less than 200 m above the decollement contains two sets of normal faults. The major set of faults dips between 50 0 and 70 0. These faults occur as conjugate pairs that are bisected by vertical extension fractures. The second set of faults
Specific goals and accomplishments of this research include: (1) The evaluation of models of salt diaper ascent that involve either power law, dislocation creep as determined experimentally by Horseman et al. (1993) or linear, fluid-assisted creep as reported by Spiers et al. (1988, 1990, 1992). We have compared models assuming these two, experimentally evaluated flow laws and examined the predictions they make regarding diaper incubation periods, ascent velocities, deviatoric stresses and strain rates. (2) The evaluation of the effects of differential loading on the initiation an of salt structures. (3) Examination of the role of basement faults on the initiation and morphologic evolution of salt structures. (4) Evaluation of the mechanical properties of shale as a function of pressure and determination of the nature of its brittle-ductile transition. (5) Evaluation of the mechanical anisotropies of shales with varying concentrations, distributions and preferred orientations of clay. (6) The determination of temperature and ratedependencies of strength for a shale constitutive model that can be used in numerical models that depend on viscous formulations. (7) Determination of the mechanisms of deformation for argillaceous rocks over awide range of conditions. (8) Evaluation of the effects of H[sub 2]O within clay interlayers, as adsorbed surface layers.
Kronenberg, A.K.; Russell, J.E.; Carter, N.L.; Mazariegos, R.; Ibanez, W.
Effects of burial history, rock ductility and recovery magnitude on inversion of normal faulted strata
Inversion of normal faults at different burial depths is studied using physical models constructed with rock and deformed at confining pressure. Models consist of a 1 cm thick limestone layer above a fault dipping 70� in a rigid medium, and are subjected to a two-stage deformation path of layer-parallel extension followed by coaxial contraction. To investigate the effects of burial depth and relative ductility on kinematics of inversion, five model suites were run in which confining pressure and recovery magnitudes were varied. In all models, a normal fault forms in the limestone during extension. Subsequent inversion is accommodated in the limestone by reverse slip on the normal fault, creation and movement along new reverse faults, and distributed fracturing and folding. The relative contribution of these mechanisms depends on the relative ductility of the rock and magnitude of inversion. Reverse slip on the normal fault and distributed fracturing occur during early stages of inversion and new reverse faults form at intermediate stages. During late stage inversion, strata with low mean ductility shorten primarily by reverse slip on the pre-existing normal fault, whereas strata with high mean ductility shorten by continued slip on reverse faults. Evidence for inversion is provided by superposed fracture fabrics in the footwall at early stages (100% recovery). This change in fracture fabric during inversion could lead to an overpressured footwall in natural inversion structures. Reverse reactivation of the normal faults may occur during coaxial contraction even though such faults are unfavorably oriented assuming typical rock friction behavior and a homogeneous stress state. Localized reverse slip on normal faults is favored when strata display low ductility and less favored when strata work-harden during extension, however, the models show that the final inversion geometry is dependent on the ductility during both phases of deformation. Even a fault that is work-hardened during extension can reactivate if the ductility during contraction is low enough.
Kuhle, Nathan John
MICRO-SEISMICITY, FAULT STRUCTURE AND HYDRAULIC COMPARTMENTALIZATION WITHIN MICRO-SEISMICITY, FAULT STRUCTURE AND HYDRAULIC COMPARTMENTALIZATION WITHIN THE COSO GETHERMAL FIELD, CALIFORNIA Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: MICRO-SEISMICITY, FAULT STRUCTURE AND HYDRAULIC COMPARTMENTALIZATION WITHIN THE COSO GETHERMAL FIELD, CALIFORNIA Details Activities (1) Areas (1) Regions (0) Abstract: High precision earthquake locations and subsurface velocity structure provide potential insights into fracture system geometry, fluid conduits and fluid compartmentalization critical to geothermal reservoir management. We analyze 16 years of seismicity to improve hypocentral locations and simultaneously invert for the seismic velocity structure within the Coso Geothermal Field (CGF). The CGF has been continuously
Reservoir Fracturing in the Geysers Hydrothermal System: Fact or Fallacy?
DOE Green Energy (OSTI)
Proper application of proven worldwide fracture determination analyses adequately aids in the detection and enhanced exploitation of reservoir fractures in The Geysers steam field. Obsolete, superficial ideas concerning fracturing in this resource have guided various malformed judgements of the actual elusive trends. Utilizing regional/local tectonics with theoretical rack mechanics and drilling statistics, offers the most favorable method of fracture comprehension. Exploitation philosophies should favor lateral drilling trends along local tensional components and under specific profound drainage/faulting manifestations to enhance high productivities. Drill core observations demonstrate various degrees of fracture filling, brecciation, strain responses, and rock fracture properties, giving the most favorable impression of subsurface reservoir conditions. Considerably more work utilizing current fracturing principles and geologic thought is required to adequately comprehend and economically exploit this huge complex resource.
Hebein, Jeffrey J.
Transient fault modeling and fault injection simulation
An accurate transient fault model is presented in this thesis. A 7-term exponential current upset model is derived from the results of a device-level, 3-dimensional, single-event-upset simulation. A curve-fitting algorithm is used to extract the numerical model from the empirical data. The model is implemented in a HSPICE simulation environment as a current-injection source for fault simulation. The current transient model is used to conduct electrical-level fault injection simulations on a static RAM cell and subcircuits from two commercial microprocessors. The results from the 7-term exponential model are compared with the results from the widely accepted double-exponential transient model. The experimental data indicate that, for a given charge level, the 7-term exponential fault model results in a higher chance of having a latch error. More importantly, different latch-error patterns are captured from the target circuits under the new fault model.
Yuan, Xuejun
Recurrent faulting and petroleum accumulation, Cat Creek Anticline, central Montana
The Cat Creek anticline, scene of central Montana's first significant oil discovery, is underlain by a south-dipping high-angle fault (Cat Creek fault) that has undergone several episodes of movement with opposite sense of displacement. Borehole data suggest that the Cat Creek fault originated as a normal fault during Proterozoic rifting concurrent with deposition of the Belt Supergroup. Reverse faulting took place in Late Cambrian time, and again near the end of the Devonian Period. The Devonian episode, coeval with the Antler orogeny, raised the southern block several hundred feet. The southern block remained high through Meramecian time, then began to subside. Post-Atokan, pre-Middle Jurassic normal faulting lowered the southern block as much as 1,500 ft. During the Laramide orogeny (latest Cretaceous-Eocene) the Cat Creek fault underwent as much as 4,000 ft of reverse displacement and a comparable amount of left-lateral displacement. The Cat Creek anticline is a fault-propagation fold; en echelon domes and listric normal faults developed along its crest in response to wrenching. Oil was generated mainly in organic-rich shales of the Heath Formation (upper Chesterian Series) and migrated upward along tectonic fractures into Pennsylvanian, Jurassic, and Cretaceous reservoir rocks in structural traps in en echelon domes. Production has been achieved only from those domes where structural closure was retained from Jurassic through Holocene time.
Nelson, W.J. (Illinois State Geological Survey, Champaign (United States))
Hydraulic fracturing-1
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
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.
Locating an active fault zone in Coso geothermal field by analyzing seismic
Locating an active fault zone in Coso geothermal field by analyzing seismic Locating an active fault zone in Coso geothermal field by analyzing seismic guided waves from microearthquake data Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Locating an active fault zone in Coso geothermal field by analyzing seismic guided waves from microearthquake data Details Activities (1) Areas (1) Regions (0) Abstract: Active fault systems usually provide high-permeability channels for hydrothermal outflow in geothermal fields. Locating such fault systems is of a vital importance to plan geothermal production and injection drilling, since an active fault zone often acts as a fracture-extensive low-velocity wave guide to seismic waves. We have located an active fault zone in the Coso geothermal field, California, by identifying and analyzing
Thoughts Regarding the Dimensions of Faults at Rainier and Aqueduct Mesas, Nye County, Nevada, Based on Surface and Underground Mapping
The geologic setting and history, along with observations through 50 years of detailed geologic field work, show that large-displacement (i.e., greater than 30 meters of displacement) syn- to post-volcanic faults are rare in the Rainier Mesa area. Faults observed in tunnels and drill holes are mostly tight, with small displacements (most less than 1.5 meters) and small associated damage zones. Faults are much more abundant in the zeolitized tuffs than in the overlying vitric tuffs, and there is little evidence that faults extend downward from the tuff section through the argillic paleocolluvium into pre-Tertiary rocks. The differences in geomechanical characteristics of the various tuff lithologies at Rainier Mesa suggest that most faults on Rainer Mesa are limited to the zeolitic units sandwiched between the overlying vitric bedded tuffs and the underlying pre-Tertiary units (lower carbonate aquifer�3, lower clastic confining unit�1, and Mesozoic granite confining unit).
Drellack, S.L.; Prothro, L.B.; Townsend, M.J.; Townsend, D.R.
Groundwater penetrating radar and high resolution seismic for locating shallow faults in unconsolidated sediments
Faults in shallow, unconsolidated sediments, particularly in coastal plain settings, are very difficult to discern during subsurface exploration yet have critical impact to groundwater flow, contaminant transport and geotechnical evaluations. This paper presents a case study using cross-over geophysical technologies in an area where shallow faulting is probable and known contamination exists. A comparison is made between Wenner and dipole-dipole resistivity data, ground penetrating radar, and high resolution seismic data. Data from these methods were verified with a cone penetrometer investigation for subsurface lithology and compared to existing monitoring well data. Interpretations from these techniques are compared with actual and theoretical shallow faulting found in the literature. The results of this study suggests that (1) the CPT study, combined with the monitoring well data may suggest that discontinuities in correlatable zones may indicate that faulting is present (2) the addition of the Wenner and dipole-dipole data may further suggest that offset zones exist in the shallow subsurface but not allow specific fault planes or fault stranding to be mapped (3) the high resolution seismic data will image faults to within a few feet of the surface but does not have the resolution to identify the faulting on the scale of our models, however it will suggest locations for upward continuation of faulted zones (4) offset 100 MHz and 200 MHz CMP GPR will image zones and features that may be fault planes and strands similar to our models (5) 300 MHz GPR will image higher resolution features that may suggest the presence of deeper faults and strands, and (6) the combination of all of the tools in this study, particularly the GPR and seismic may allow for the mapping of small scale, shallow faulting in unconsolidated sediments.
Wyatt, D.E. [Westinghouse Savannah River Co., Aiken, SC (United States)]|[South Carolina Univ., Columbia, SC (United States). Earth Sciences and Resources Inst.; Waddell, M.G. [South Carolina Univ., Columbia, SC (United States). Earth Sciences and Resources Inst.; Sexton, B.G. [Microseeps Ltd., Pittsburgh, PA (United States)
Structural geology of Shawneetown fault zone, Southeastern Illinois
Vertical movements of crustal blocks along the narrow east-west-trending Shawneetown fault zone in southeastern Illinois occurred between Early Permian and Late Cretaceous. The main blocks moved vertically and retured to roughly their orignal positions so that strata now show little relative offset across the fault zone. However, individual faults with displacements up to 3,500 ft (1,070 m) bound narrow slices of steeply tilted or overturned strata resulting in a juxtaposition of Kinderhookian (Lower Mississippian) and Upper Devonian strata with Lower Pennsylvanina strata. The bedrock is intensely fractured, commonly brecciated, and cemented with either silica or calcite. Slickensides and mullion display various orientations within the zone and on individual outcrops. The dominant movement, however, appears to be vertical with no evidence for significant strike-slip movements. Pleistocene deposits do not exhibit offsets across the fault zone, indicating that no tectonic activity has occurred since the beginning of that epoch. The trend of the fault zone changes abruptly from east-west in southern Gallatin and easternmost Saline Counties to south-southwest in southern Saline and northeastern Pope Counties, where it joins the Fluorspar area fault complex. Here the zone widens and develops a braided pattern as the amount of displacement along individual faults decreases. The Shawneetown fault zone and Flourspar area fault complex in part are younger than the Cottage Grove fault system to the northwest and the Wabash Valley fault system to the north. The hope of finding structural traps near the junctions of the fuel systems has spurred recent oil exploration in the area.
Lumm, D.K.; Nelson, W.J.
Fault Current Limiters
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
Fault Fault Current Limiters Superconducting & Solid-state Power Equipment Office of Electricity Delivery and Energy Reliability www.oe.energy.gov Office of Electricity Delivery and Energy Reliability, OE-1 U.S. Department of Energy - 1000 Independence Avenue, SW - Washington, DC 20585 Plugging America Into the Future of Power What are FCLs? A fault is an unintentional short circuit, or partial short-circuit, in an electric circuit. A variety of factors such as lightning, downed power lines, or crossed power lines cause faults. During a fault, excessive current-called fault current- flows through the electrical system often resulting in a failure of one section of that system by causing a
Automatic detection of lithologic boundaries using the Walsh transform: A case study from the KTB borehole
An automatic method of lithologic boundary detection based on Walsh transform theory is developed and applied to the German Continental Deep Drilling Project (KTB) borehole well log data. Walsh functions are natural choices for describing binary waveforms; ... Keywords: Borehole geophysics, KTB, Low-pass filtering, Rock boundary detection, Walsh transforms
Saumen Maiti; R. K. Tiwari
Application of Self-Organizing Competitive Network in Lithologic Identification of the Logging Data
The geological information of logging data is very important for people to determine oil reserves and make the plan of exploitation. So it is essential to identify litho logy of the logging data. Neural network with self-organizing, self-learning and ... Keywords: self-organizing, competitive network, log data to identify lithology, MATLAB
Ren Guo-Feng; Tian Zhu-Mei
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.
Lithology identification of aquifers from geophysical well logs and fuzzy logic analysis: Shui-Lin Area, Taiwan
The purpose of this study is to construct a fuzzy lithology system from well logs to identify formation lithology of a groundwater aquifer system in order to better apply conventional well logging interpretation in hydro-geologic studies because well ... Keywords: Aquifer characterization, Artificial intelligence, Groundwater, Hydrogeology, Soft computing
Bieng-Zih Hsieh; Charles Lewis; Zsay-Shing Lin
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
Solar system fault detection
A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combining the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.
Farrington, R.B.; Pruett, J.C. Jr.
Farrington, Robert B. (Wheatridge, CO); Pruett, Jr., James C. (Lakewood, CO)
Microstructures and Rheology of a Limestone-Shale Thrust Fault
The Copper Creek thrust fault in the southern Appalachians places Cambrian over Ordovician sedimentary strata. The fault accommodated displacement of 15-20 km at 100-180 �C. Along the hanging wall-footwall contact, microstructures within a ~2 cm thick calcite and shale shear zone suggest that calcite, not shale, controlled the rheology of the shear zone rocks. While shale deformed brittley, plasticity-induced fracturing in calcite resulted in ultrafine-grained (shale into the shear zone, shows the evolution of rheology within the shear zone. Sedimentary laminations 1 cm below the shear zone are cut by minor faults, stylolites, and fault-parallel and perpendicular calcite veins. At vein intersections, calcite grain size is reduced (to ~0.3 ?m), and microstructures include inter-and-intragranular fractures, four-grain junctions, and interpenetrating boundaries. Porosity rises to 6 percent from shale clasts (5-350 ?m) lie within an ultrafine-grained calcite (shale matrix. Ultrafinegrained calcite (shale. Calcite vein microstructures suggest veins continued to form during deformation. Fractures at twin-twin and twin-grain boundary intersections suggest grain size reduction by plasticity-induced fracturing, resulting in <1 ?m grains. Interpenetrating boundaries, four-grain junctions, and no LPO indicate the ultrafine-grained calcite deformed by viscous grain boundary sliding. The evolution of the ultrafine-grain shear zone rocks by a combination of plastic and brittle processes and the deformation of the interconnected network of ultrafine-grained calcite by viscous GBS enabled a large displacement along a narrow fault zone.
Wells, Rachel Kristen
Linear Elastic Fracture Mechanics
..., ASM International, 1996, p 371�??380ASM Handbook, Vol 19, Fatigue And FractureS.D. Antolovich and B.F. Antolovich, An Introduction to Fracture
Paleoseismic investigations of Stagecoach Road fault, southeastern Yucca Mountain, Nye County, Nevada
This report summarizes the results of paleoseismic investigations at two trenches (SCR-T1 and SCR-T3) excavated across the Stagecoach Road (SCR) fault at the southeastern margin of Yucca Mountain. The results of these studies are based on detailed mapping or logging of geologic and structural relationships exposed in trench walls, combined with descriptions of lithologic units, associated soils, and fault-related deformation. The ages of trench deposits are determined directly from geochronologic dating of selected units and soils, supplemented by stratigraphic and soil correlations with other surficial deposits in the Yucca Mountain area. The time boundaries used in this report for subdivision of the Quaternary period are listed in a table. These data and interpretations are used to identify the number, amounts, timing, and approximately lengths of late to middle Quaternary (less than 200 ka) surface-faulting events associated with paleoearthquakes at the trench sites. This displacement history forms the basis for calculating paleoearthquake recurrence intervals and fault-slip rates for the Stagecoach Road fault and allows comparison with fault behavior on other Quaternary faults at or near Yucca Mountain.
Menges, C.M.; Oswald, J.A.; Coe, J.A.; Lundstrom, S.C.; Paces, J.B.; Mahan, S.A.; Widmann, B.; Murray, M.
Optimal fault location
Basic goal of power system is to continuously provide electrical energy to the users. Like with any other system, failures in power system can occur. In those situations it is critical that correct remedial actions are applied as soon as possible after the accurate fault condition and location are detected. This thesis has been focusing on automated fault location procedure. Different fault location algorithms, classified according to the spatial placement of physical measurements on single ended, multiple ended and sparse system-wide, are investigated. As outcome of this review, methods are listed as function of different parameters that influence their accuracy. This comparison is than used for generating procedure for optimal fault location algorithm selection. According to available data, and position of the fault with respect to the data, proposed procedure decides between different algorithms and selects an optimal one. A new approach is developed by utilizing different data structures such as binary tree and serialization in order to efficiently implement algorithm decision engine. After accuracy of algorithms is strongly influenced by available input data, different data sources are recommended in proposed architecture such as the digital fault recorders, circuit breaker monitoring, SCADA, power system model and etc. Algorithm for determining faulted section is proposed based on the data from circuit breaker monitoring devices. This algorithm works in real time by recognizing to which sequence of events newly obtained recording belongs. Software prototype of the proposed automated fault location analysis is developed using Java programming language. Fault location analysis is automatically triggered by appearance of new event files in a specific folder. The tests were carried out using the real life transmission system as an example.
Knezev, Maja
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.
The Influence of Fold and Fracture Development on Reservoir Behavior of the Lisburne Group of Northern Alaska
The objectives of this study were to develop a better understanding of four major aspects of the Lisburne: (1) The geometry and kinematics of detachment folds and their truncation by thrust faults, (2) The influence of folding and lithostratigraphy on fracture patterns, (3) Lithostratigraphy and its influence on folding, faulting, fracturing, and reservoir characteristics, and (4) The influence of lithostratigraphy and deformation on fluid flow.
Wallace, W.K.; Hanks, C.L.; Whalen, M.T.; Jensen, J.; Atkinson, P.K.; Brinton, J.S.
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
Advanced Characterization of Fractured Reservoirs in Carbonate Rocks: The Michigan Basin
The purpose of the study was to collect and analyze existing data on the Michigan Basin for fracture patterns on scales ranging form thin section to basin. The data acquisition phase has been successfully concluded with the compilation of several large digital databases containing nearly all the existing information on formation tops, lithology and hydrocarbon production over the entire Michigan Basin. These databases represent the cumulative result of over 80 years of drilling and exploration.
Wood, James R.; Harrison, William B.
The importance of in-situ-stress profiles in hydraulic-fracturing applications
In-situ stresses define the local forces acting on lithologic layers in the subsurface. Knowledge of these stresses is important in drilling, wellbore-stability, and, especially, hydraulic-fracturing applications. The measurement of in-situ stress is not straightforward and, therefore, often goes unmeasured. As such, one often assumes values of in-situ stress or estimate in-situ stresses from logging parameters. This article illustrates the importance of in-situ-stress estimates as they relate to hydraulic fracturing and outlines several techniques for estimating in-situ-stress magnitudes.
Hopkins, C.W. [S.A. Holditch and Associates, Inc., Houston, TX (United States). Houston Div.
Lithology and Stratigraphy of Holes Drilled in LANL-Use Areas of the Nevada Test Site
Geologic data for ten holes drilled in areas used by Los Alamos National Laboratory at the Nevada Test Site are presented in this report. The holes include emplacement holes, instrumentation holes, and Underground Test Area wells drilled during calendar years 1991 through 1995. For each hole a stratigraphic log, a detailed lithologic log, and one or two geologic cross sections are presented, along with a supplemental data sheet containing information about the drilling operations, geology, or references. For three of the holes, graphic data summary sheets with geologic and geophysical data are provided as plates.
Lance B. Prothro; Sigmund L. Drellack, Jr.; Brian M. Allen
Intersecting faults and sandstone stratigraphy at the Cerro Prieto geothermal field
The northwest-southeast trending Cerro Prieto fault is part of a major regional lineament that extends into Sonaro and has characteristics of both a wrench fault and an oceanic transform fault. The distribution of lithologies and temperature within the field was studied by comparing data from well cuttings, cores, well logs, and geochemical analyses. Across the earliest developed portion of the field, in particular along a 1.25-km northeast-southwest section from well M-9 to M-10, interesting correlations emerge that indicate a relationship among lithology, microfracturing, and temperature distribution. In the upper portion of Reservoir A of this stratigraphic section, between 1200 and 1400 m, the percentage of sandstones ranges from 20 to 55. Temperatures are 225/sup 0/ to 275/sup 0/C based on well logs, calcite isotope maxima, and Na-K-Ca indices. The study shows that an isothermal high in this vicinity corresponds to the lowest total percentage of sandstones. Scanning electron microphotographs of well cores and cuttings from sandstone and shale units reveal clogging, mineral dissolution, and mineral precipitation along microfractures. The working hypothesis is that these sandy shale and siltstone facies are most amenable to increased microfracturing and, in turn, such microfracturing allows for higher temperature fluid to rise to shallower depths in the reservoir.
Vonder Haar, S.; Howard, J.H.
Parallel fault backtracing for calculation of fault coverage
A new improved method for calculation of fault coverage with parallel fault backtracing in combinational circuits is proposed. The method is based on structurally synthesized BDDs (SSBDD) which represent gate-level circuits at higher, macro level where ...
Raimund Ubar; Sergei Devadze; Jaan Raik; Artur Jutman
Fracture Permeability and in Situ Stress in the Dixie Valley, Nevada, Geothermal Reservoir
We have collected and analyzed fracture and fluid flow data from wells both within and outside the producing geothermal reservoir at Dixie Valley. Data from wellbore imaging and flow tests in wells outside the producing field that are not sufficiently hydraulically connected to the reservoir to be of commercial value provide both the necessary control group of fracture populations and an opportunity to test the concepts proposed in this study on a regional, whole-reservoir scale. Results of our analysis indicate that fracture zones with high measured permeabilities within the producing segment of the fault are parallel to the local trend of the Stillwater fault and are optimally oriented and critically stressed for frictional failure in the overall east-southeast extensional stress regime measured at the site. In contrast, in the non-producing (i.e., relatively impermeable:) well 66-21 the higher ratio of S{sub hmin} to S{sub v} acts to decrease the shear stress available to drive fault slip. Thus, although many of the fractures at this site (like the Stillwater fault itself) are optimally oriented for normal faulting they are not critically stressed for frictional failure. Although some of the fractures observed in the non-producing well 45-14 are critically stressed for frictional failure, the Stillwater fault zone itself is frictionally stable. Thus, the high horizontal differential stress (i.e., S{sub Hmax}-S{sub hmin}) together with the severe misorientation of the Stillwater fault zone for normal faulting at this location appear to dominate the overall potential for fluid flow.
M. D. Zoback
A differential fault sensing circuit is designed for detecting arcing in high-voltage vacuum tubes arranged in parallel. A circuit is provided which senses differences in voltages appearing between corresponding elements likely to fault. Sensitivity of the circuit is adjusted to some level above which arcing will cause detectable differences in voltage. For particular corresponding elements, a group of pulse transformers are connected in parallel with diodes connected across the secondaries thereof so that only voltage excursions are transmitted to a thyratron which is biased to the sensitivity level mentioned.
Roberts, J.H.
Computer hardware fault administration
Computer hardware fault administration carried out in a parallel computer, where the parallel computer includes a plurality of compute nodes. The compute nodes are coupled for data communications by at least two independent data communications networks, where each data communications network includes data communications links connected to the compute nodes. Typical embodiments carry out hardware fault administration by identifying a location of a defective link in the first data communications network of the parallel computer and routing communications data around the defective link through the second data communications network of the parallel computer.
Archer, Charles J. (Rochester, MN); Megerian, Mark G. (Rochester, MN); Ratterman, Joseph D. (Rochester, MN); Smith, Brian E. (Rochester, MN)
High velocity impact fracture
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
Controls on Fault-Hosted Fluid Flow: Preliminary Results from the Coso
Controls on Fault-Hosted Fluid Flow: Preliminary Results from the Coso Controls on Fault-Hosted Fluid Flow: Preliminary Results from the Coso Geothermal Field, CA Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Controls on Fault-Hosted Fluid Flow: Preliminary Results from the Coso Geothermal Field, CA Details Activities (1) Areas (1) Regions (0) Abstract: cap rock, permeability, fault, fracture, clay, Coso Author(s): Davatzes, N.C.; Hickman, S.H. Published: Geothermal Resource Council Transactions 2005, 1/1/2005 Document Number: Unavailable DOI: Unavailable Conceptual Model At Coso Geothermal Area (2005-2007) Coso Geothermal Area Retrieved from "http://en.openei.org/w/index.php?title=Controls_on_Fault-Hosted_Fluid_Flow:_Preliminary_Results_from_the_Coso_Geothermal_Field,_CA&oldid=473359"
Experimental study of fracture development in multilayers of contrasting strength and ductility
The effect of mean ductility, interlayer thickness, and magnitude of shortening on fracture development in bedded rock was investigated by shortening multilayer cylinders (5 cm dia.) 4 to 14% normal to layering in a triaxial apparatus. Multilayers were constructed by stacking two 1.4-cm thick layers of Berea Sandstone (relatively strong and brittle) with interlayers of Indiana Limestone (relatively weak and ductile). Thickness of the interlayer between the sandstone was 30%, 100%, or 150% of the thickness of the sandstone layer. Mean ductility was varied by shortening at confining pressures (Pc) of 5, 25, 50, and 100 MPa. Sandstone layers fracture at all conditions. Fractures have preferred orientation symmetric to the cylinder axis, and display systematic spacing. At the lowest Pc and mean ductility, fractures in the sandstone are dominantly opening mode (joints) and mixed mode fractures oriented at high angles to layer boundaries. At greater Pc and mean ductility, fractures are dominantly shear mode (faults) and display conjugate geometry. Average dihedral angle of the conjugates increases from 16 to 67 degrees with increase in mean ductility. Maximum fracture density in the sandstone occurs at intermediate mean ductility and maximum interlayer thickness. Fractures propagate from the sandstone into the limestone and may link across the limestone interlayer as shortening is increased. Linkage is enhanced with decreasing mean ductility and interlayer thickness, and increasing shortening. At high mean ductility, fractures are confined to the sandstone layers. Limestone deforms by faulting and compactive cataclastic flow at low and high mean ductility, respectively. Faults in limestone are more variable in orientation and display larger dihedral angles than in the sandstone. Fracture mode and orientation are consistent with Mohr-Coulomb failure, and a spatially heterogeneous stress state where the most tensile stress occurs in the sandstone. Types of fracture networks in multilayer sequences with moderate ductility contrast vary from joints and faults, refracted faults, to faults and flow with increasing mean ductility. Fracture spacing depends on layer and interlayer thickness, mean ductility and ductility contrast, and magnitude of shortening.
Cubuk, Pelin
Dynamic Fault Detection Chassis
Abstract The high frequency switching megawatt-class High Voltage Converter Modulator (HVCM) developed by Los Alamos National Laboratory for the Oak Ridge National Laboratory's Spallation Neutron Source (SNS) is now in operation. One of the major problems with the modulator systems is shoot-thru conditions that can occur in a IGBTs H-bridge topology resulting in large fault currents and device failure in a few microseconds. The Dynamic Fault Detection Chassis (DFDC) is a fault monitoring system; it monitors transformer flux saturation using a window comparator and dV/dt events on the cathode voltage caused by any abnormality such as capacitor breakdown, transformer primary turns shorts, or dielectric breakdown between the transformer primary and secondary. If faults are detected, the DFDC will inhibit the IGBT gate drives and shut the system down, significantly reducing the possibility of a shoot-thru condition or other equipment damaging events. In this paper, we will present system integration considerations, performance characteristics of the DFDC, and discuss its ability to significantly reduce costly down time for the entire facility.
Mize, Jeffery J [ORNL
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
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
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.
Fault Current Management Guidebook - Updated
Under the new paradigm of power market operation, electric utilities are forcing more power through the existing transmission lines; and these increased loads will increase the fault current level throughout the power system. Also, new generation sources including distributed generation added at the transmission and distribution network will increase power flows and, consequently, fault current levels. Under increased power flow conditions on the existing assets, managing fault currents is crucial in ord...
New observations of infiltration through fractured alluvium in Yucca Flat, Nevada Test Site: A preliminary field investigation
Regional tectonics coupled with the subsurface detonation of nuclear explosives has caused widespread fracturing of the alluvium of Yucca Flat. Fractures deeper than 30 meters have been observed in boreholes. Some of these fractures are large enough to capture significant amounts of runoff during storm events. Evidence of stream capture by fractures and observations of runoff flowing into open fractures give qualitative evidence of infiltration to depths greater than several meters and possibly to the saturated zone. Our field observations contradict the assumption that little infiltration occurs on Yucca Flat. The larger, hydrologically important fractures are associated with geologic faults or the regional stress field. Additional field studies are needed to investigate the impact of fractures on the transport of contaminants.
Kao, C.S. [California Univ., Berkeley, CA (United States). Dept. of Civil Engineering; Smith, D.K. [Lawrence Livermore National Lab., CA (United States); McKinnis, W.B. [Lawrence Livermore National Lab., Mercury, NV (United States)
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
Tectonic controls on fracture permeability in a geothermal reservoir at Dixie Valley, Nevada
To help determine the nature and origins of permeability variations within a fault-hosted geothermal reservoir at Dixie Valley, Nevada, the authors conducted borehole televiewer logging and hydraulic fracturing stress measurements in six wells drilled into the Stillwater fault zone at depths of 2--3 km. Televiewer logs from wells penetrating the highly permeable portion of the fault zone revealed extensive drilling-induced tensile fractures. As the Stillwater fault at this location dips S45{degree}E at {approximately} 53{degree} it is nearly at the optimal orientation for normal faulting in the current stress field. Hydraulic fracturing tests from these permeable wells show that the magnitude of S{sub hmin} is very low relative to the vertical stress S{sub v}. Similar measurements conducted in two wells penetrating a relatively impermeable segment of the Stillwater fault zone 8 and 20 km southwest of the producing geothermal reservoir indicate that the orientation of S{sub hmin} is S20{degree}E and S41{degree}E, respectively, with S{sub hmin}/S{sub v} ranging from 0.55--0.64 at depths of 1.9--2.2 km. This stress orientation is near optimal for normal faulting on the Stillwater fault in the northernmost non-producing well, but {approximately} 40{degree} rotated from the optimal orientation for normal faulting in the southernmost well. The observation that borehole breakouts were present in these nonproducing wells, but absent in wells drilled into the permeable main reservoir, indicates a significant increase in the magnitude of maximum horizontal principal stress, S{sub Hmax}, in going from the producing to non-producing segments of the fault. The increase in S{sub Hmaz}, coupled with elevated S{sub hmin}/S{sub v} values and a misorientation of the Stillwater fault zone with respect to the principal stress directions, leads to a decrease in the proximity of the fault zone to Coulomb failure. This suggests that a necessary condition for high reservoir permeability is that the Stillwater fault zone be critically stressed for frictional failure in the current stress field.
Hickman, S. [Geological Survey, Menlo Park, CA (United States); Zoback, M. [Stanford Univ., CA (United States). Dept. of Geophysics
Major Normal Fault | Open Energy Information
Major Normal Fault Major Normal Fault Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Print PDF Major Normal Fault Dictionary.png Major Normal Fault: Normal faults are structures in which the hanging wall is down dropped along the fault plane relative to the foot wall. They are the predominant type of structure in extensional tectonic environments, but are commonly encountered in a number of geologic settings. Other definitions:Wikipedia Reegle Controlling Structures List of controlling structures typically associated with geothermal systems: Major Normal Fault Termination of a Major Normal Fault Stepover or Relay Ramp in Normal Fault Zones Apex or Salient of Normal Fault Fault Intersection Accommodation Zone Displacement Transfer Zone Pull-Apart in Strike-Slip Fault Zone
Multiple signal fault detection using fuzzy logic
In this paper, we describe a multiple Signal Fault Detection system that employs fuzzy logic at two levels of detection: signal segment fault and signal fault. The system involves signal segmentation, feature extraction and fuzzy logic based segment ...
Yi Lu Murphey; Jacob Crossman; ZhiHang Chen
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.
Vertical arrays for fracture mapping in geothermal systems
In collaboration with UNOCAL Geothermal Operations, Los Alamos National Laboratory assessed the feasibility of using vertical arrays of borehole seismic sensors for mapping of microseismicity in The Geysers geothermal field. Seismicity which arises from minute displacements along fracture or fault surfaces has been shown in studies of seismically active oil reservoirs to be useful in identifying fractures affected by and possibly contributing to production. Use of retrievable borehole seismic packages at The Geysers was found to reduce the threshold for detection of microearthquakes by an estimated 2--3 orders of magnitude in comparison to surface-based sensors. These studies led to the design, materials selection, fabrication, and installation of a permanent array of geophones intended for long term seismic monitoring and mapping of fractures in the vicinity of the array at The Geysers.
Albright, J.N. [Los Alamos National Lab., NM (United States); Rutledge, J.T.; Fairbanks, T.D. [Nambe Geophysics, Inc. (United States); Thomson, J.C. [Lithos Inc. (United States); Stevenson, M.A. [Petroleum Geo-Services (United States)
Stress and fault rock controls on fault zone hydrology, Coso...
often function as hydrologic barriers separating regions of distinct fluid inclusion chemistry and temperature gradient. Distributed fracture networks play only a minor role in...
Definition: Enhanced Fault Protection | Open Energy Information
Enhanced Fault Protection Enhanced Fault Protection Enhanced fault protection requires higher precision and greater discrimination of fault location and type with coordinated measurement among multiple devices. For distribution applications, these systems will detect and isolate faults without full-power re-closing, reducing the frequency of through-fault currents. Using high resolution sensors and fault signatures, these systems can better detect high impedance faults. For transmission applications, these systems will employ high speed communications between multiple elements (e.g., stations) to protect entire regions, rather than just single elements. They will also use the latest digital techniques to advance beyond conventional impedance relaying of transmission lines.[1] Related Terms
Definition: Fault Mapping | Open Energy Information
Mapping Jump to: navigation, search Dictionary.png Fault Mapping Faults are structural features of crustal rocks that are caused by tectonic forces. These features can create...
Fold Catastrophe Model of Fracture Propagation of Hydraulic Fracturing
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
Evaluation of the relationship between fracture conductivity, fracture fluid production, and effective fracture length
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.
Observer-based fault detection for nuclear reactors
This is a study of fault detection for nuclear reactor systems. Basic concepts are derived from fundamental theories on system observers. Different types of fault- actuator fault, sensor fault, and system dynamics fault ...
Li, Qing, 1972-
Arc fault detection system
An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard.
Jha, Kamal N. (Bethel Park, PA)
An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard. 1 fig.
Jha, K.N.
Fracturing fluids -- then and now
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)
Suspensions in hydraulic fracturing
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)
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.
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
EPRI Fault Current Management Guidebook, Fifth Edition
This document is an update of EPRI report 1020029, Fault Current Management Guidebook, Fourth Edition, on fault current effects and management in transmission and distribution systems. This guide is intended to be a snapshot of available references, information, and literature on the effects of high fault current on a number of power system components and various available and emerging fault-current-limiting technologies.
Memory Fault Modeling Trends: A Case Study
In recent years, embedded memories are the fastest growing segment of system on chip. They therefore have a major impact on the overall Defect per Million (DPM). Further, the shrinking technologies and processes introduce new defects that cause previously ... Keywords: data backgrounds, dynamic faults, fault coverage, fault models, memory tests, static faults
Said Hamdioui; Rob Wadsworth; John Delos Reyes; Ad J. Van De Goor
Stratigraphic Boundaries | Open Energy Information
Stratigraphic Boundaries Stratigraphic Boundaries Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Print PDF Stratigraphic Boundaries Dictionary.png Stratigraphic Boundaries: No definition has been provided for this term. Add a Definition Controlling Structures List of controlling structures typically associated with geothermal systems: Major Normal Fault Termination of a Major Normal Fault Stepover or Relay Ramp in Normal Fault Zones Apex or Salient of Normal Fault Fault Intersection Accommodation Zone Displacement Transfer Zone Pull-Apart in Strike-Slip Fault Zone Intrusion Margins and Associated Fractures Stratigraphic Boundaries Fissure Swarms Caldera Rim Margins Lithologically Controlled Hydrothermal circulation may occur at the contacts between different lithologies. Examples
The goal of this project was to develop a method to exploit viscoelastic rock and fluid properties to greatly enhance the sensitivity of surface seismic measurements to the presence of hydrocarbon saturation. To reach the objective, Southwest Research Institute scientists used well log, lithology, production, and 3D seismic data from an oil reservoir located on the Waggoner Ranch in north central Texas. The project was organized in three phases. In the first phase, we applied modeling techniques to investigate seismic- and acoustic-frequency wave attenuation and its effect on observable wave attributes. We also gathered existing data and acquired new data from the Waggoner Ranch field, so that all needed information was in place for the second phase. During the second phase, we developed methods to extract attenuation from borehole acoustic and surface seismic data. These methods were tested on synthetic data constructed from realistic models and real data. In the third and final phase of the project, we applied this technology to a full data set from the Waggoner site. The results presented in this Final Report show that geological conditions at the site did not allow us to obtain interpretable results from the Q processing algorithm for 3D seismic data. However, the Q-log processing algorithm was successfully applied to full waveform sonic data from the Waggoner site. A significant part of this project was technology transfer. We have published several papers and conducted presentations at professional conferences. In particular, we presented the Q-log algorithm and applications at the Society of Exploration Geophysicists (SEG) Development and Production Forum in Austin, Texas, in May 2005. The presentation attracted significant interest from the attendees and, at the request of the SEG delegates, it was placed on the Southwest Research Institute Internet site. The presentation can be obtained from the following link: http://www.swri.org/4org/d15/elecsys/resgeo/ppt/Algorithm.pps In addition, we presented a second application of the Q algorithm at the SEG International Conference in Houston, Texas, in May 2005. The presentation attracted significant interest there as well, and it can be obtained from the following link: http://www.swri.org/4org/d15/elecsys/resgeo/ppt/attenuation.pps.
Jorge O. Parra; C.L. Hackert; L. Wilson; H.A. Collier; J. Todd Thomas
Fault Tree Analysis - A Bibliography
Fault tree analysis is a top-down approach to the identification of process hazards. It is touted as one of the best methods for systematically identifying and graphically displaying the many ways something can go wrong. This bibliography references ...
Program NASA Scientific and Technical Information
SWIFT: Software Implemented Fault Tolerance
To improve performance and reduce power, processor designers employ advances that shrink feature sizes, lower voltage levels, reduce noise margins, and increase clock rates. However, these advances make processors more susceptible to transient faults ...
George A. Reis; Jonathan Chang; Neil Vachharajani; Ram Rangan; David I. August
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
Hydraulic Fracturing Poster Hydraulic Fracturing Poster Educational poster graphically displaying the key components of hydraulic fracturing. Teachers: If you would like hard...
and T. W. Keech (1977), Hydraulic fracture mapping usingpotential measurements during hydraulic fracturing of BunterSP Monitoring during hydraulic fracturing using the TG-2
Passive fault current limiting device
A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment. 6 figs.
Evans, D.J.; Cha, Y.S.
Lithologic characterization using magnetic and gravity gradient data over an iron ore formation Cericia Martinez,Yaoguo Li, Richard Krahenbuhl, Marco Braga
and Guillen (2005) have explored inversion guided by lithologic categories with density and susceptibility., and A. Guillen, 2005, Geologically-inspired Constraints for a Potential Field Litho-inversion Scheme
During the past six months we have adapted our 3-D elastic, anisotropic finite difference code by implementing the rotated staggered grid (RSG) method to more accurately represent large contrasts of elastic moduli between the fractures and surrounding formation, and applying the perfectly matched layer (PML) absorbing boundary condition to minimize boundary reflections. Two approaches for estimating fracture spacing from scattered seismic energy were developed. The first relates notches in the amplitude spectra of the scattered wavefield to the dominant fracture spacing that caused the scattering. The second uses conventional FK filtering to isolate the backscattered signals and then recovers an estimate of the fracture spacing from the dominant wavelength of those signals. Both methods were tested on synthetic data and then applied to the Emilio field data. The spectral notch method estimated the Emilio fracture spacing to be about 30 to 40 m, while the FK method found fracture spacing of about 48 to 53 m. We continue to work on two field data sets from fractured carbonate reservoirs provided by our industry sponsors--the offshore Emilio Field data (provided by ENIAGIP), and an onshore reservoir from the Middle East (provided by Shell). Calibration data in the form of well logs and previous fracture studies are available for both data sets. In previous reports we showed the spatial distribution fractures in the Emilio Field based on our calculated scattering index values. To improve these results we performed a map migration of all the scattering indices. The results of this migration process show a very strong correlation between the spatial distribution and orientation of our estimated fracture distribution and the fault system in the field. We observe that the scattering index clusters tend to congregate around the fault zones, particularly near multiple faults and at fault tips. We have also processed a swath of data from the second data set (the onshore carbonate field). FMI data are available from a number of wells for comparison to our seismic scattering analysis results. The agreement is very good, providing confidence that these methods can be applied to land seismic data that do not have the ideal azimuthal coverage.
Daniel R. Burns; M. Nafi Toksoz
Experimental study of the transition from brittle shear fractures to joints
Current geologic thinking is that there are two, and only two, distinct types of brittle fractures, joints and shear fractures (faults). For over half a century, it has been debated that a third type of fracture, referred to as hybrid fractures, could exist and that joints and shear fractures may be end members of a continuous spectrum of brittle fractures. Hybrid fractures are hypothesized to form under mixed compressive and tensile stress states and have structural characteristics intermediate to those of joints and shear fractures. While this hypothesis is accepted in many modern structural geology textbooks used at the college and graduate level, no unchallenged evidence exists for the existence of hybrid fractures. Following the general methodology of a previously performed study by W.F. Brace (1964), but incorporating several key modifications to the experimental methods, a series of dog-bone triaxial experiments were performed on Carrara marble at room temperature, an axial extension rate of 2x10?� mm s?�, and confining pressures between 7.5 and 170 MPa. The experiments provide strong evidence for the existence of hybrid fractures on the basis of the progressive change in fracture orientation, surface morphology, and failure strength between end-member joints and shear fractures. At the lowest confining pressures (7.5 to 60 MPa), fractures are oriented approximately parallel to the maximum principal stress, []?, form at an axial stress []?, of approximately -7.75 MPa (i.e. the uniaxial tensile strength), and display fracture surfaces characterized by many reflective cleavage faces, consistent with jointing. At the highest confining pressures (130 to 170 MPa), fractures are oriented from 13.4? to 21.6? to []?, form under completely compressive stress states with []? between 0 and 4.3 MPa, and are characterized by powdery white surfaces with short slip lineations, consistent with shear fracturing. At intermediate confining pressures (70 to 120 MPa), fractures are oriented from 3.7? to 12.4? to []?, form under mixed stress conditions with s3 ranging from -10.6 to -3.0 MPa, and display both reflective cleavage faces and powdery white surfaces with short slip lineations, consistent with hybrid fracturing.
Ramsey, Jonathan Michael
Gravity and fault structures, Long Valley caldera, California
The main and catastrophic phase of eruption in Long Valley occurred 0.73 m.y. ago with the eruption of over 600 km/sup 3/ of rhyolitic magma. Subsequent collapse of the roof rocks produced a caldera which is now elliptical in shape, 32 km east-west by 17 km north-south. The caldera, like other large Quarternary silicic ash-flow volcanoes that have been studied by various workers, has a nearly coincident Bouguer gravity low. Earlier interpretations of the gravity anomaly have attributed the entire anomaly to lower density rocks filling the collapsed structure. However, on the basis of many additional gravity stations and supporting subsurface data from several new holes, a much more complex and accurate picture has emerged of caldera structure. From a three-dimensional inversion of the residual Bouguer gravity data we can resolve discontinuities that seem to correlate with extensions of pre-caldera faults into the caldera and faults associated with the ring fracture. Some of these faults are believed related to the present-day hydrothermal upflow zone and the zone of youngest volcanic activity within the caldera.
Carle, S.F.; Goldstein, N.E.
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,
Fault detection of fault ride through for doubly-fed induction generator based wind energy systems.
??Fault detection and mitigation is of high importance for existing DFIG based wind energy conversion systems. Keeping the doubly-fed induction generator (DFIG) online during faults� (more)
Ramroop, Shoba AD
Automatic fault extraction and simulation of layout realistic faults for integrated analogue circuits
A comprehensive tool has been implemented for the comparison of different test preparation techniques and target faults. It comprises of the realistic fault characterisation program LIFT that can extract sets of various faults from a given analogue or ... Keywords: AnaFAUL, LIFT, VCO, analogue integrated circuits, automatic analogue fault simulation program, catastrophic faults, circuit analysis computing, circuit layout, fault diagnosis, integrated analogue circuits, integrated circuit layout, integrated circuit testing, mixed analogue-digital integrated circuits, mixed-signal circuit, parametric faults, realistic fault characterisation program, simulation, test preparation, voltage-controlled oscillators
C. Sebeke; J. P. Teixeira; M. J. Ohletz
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.
Fracture characterization of multilayered reservoirs
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.
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-
Rigid Body Simulation with Local Fracturing Effects
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
Discrete Fracture Network Models for Risk Assessment of Carbon Sequestration in Coal
A software package called DFNModeler has been developed to assess the potential risks associated with carbon sequestration in coal. Natural fractures provide the principal conduits for fluid flow in coal-bearing strata, and these fractures present the most tangible risks for the leakage of injected carbon dioxide. The objectives of this study were to develop discrete fracture network (DFN) modeling tools for risk assessment and to use these tools to assess risks in the Black Warrior Basin of Alabama, where coal-bearing strata have high potential for carbon sequestration and enhanced coalbed methane recovery. DFNModeler provides a user-friendly interface for the construction, visualization, and analysis of DFN models. DFNModeler employs an OpenGL graphics engine that enables real-time manipulation of DFN models. Analytical capabilities in DFNModeler include display of structural and hydrologic parameters, compartmentalization analysis, and fluid pathways analysis. DFN models can be exported to third-party software packages for flow modeling. DFN models were constructed to simulate fracturing in coal-bearing strata of the upper Pottsville Formation in the Black Warrior Basin. Outcrops and wireline cores were used to characterize fracture systems, which include joint systems, cleat systems, and fault-related shear fractures. DFN models were constructed to simulate jointing, cleating, faulting, and hydraulic fracturing. Analysis of DFN models indicates that strata-bound jointing compartmentalizes the Pottsville hydrologic system and helps protect shallow aquifers from injection operations at reservoir depth. Analysis of fault zones, however, suggests that faulting can facilitate cross-formational flow. For this reason, faults should be avoided when siting injection wells. DFN-based flow models constructed in TOUGH2 indicate that fracture aperture and connectivity are critical variables affecting the leakage of injected CO{sub 2} from coal. Highly transmissive joints near an injection well have potential to divert a large percentage of an injected CO{sub 2} stream away from a target coal seam. However, the strata-bound nature of Pottsville fracture systems is a natural factor that mitigates the risk of long-range leakage and surface seepage. Flow models indicate that cross-formational flow in strata-bound joint networks is low and is dissipated by about an order of magnitude at each successive bedding contact. These models help confirm that strata-bound joint networks are self-compartmentalizing and that the thick successions of interbedded shale and sandstone separating the Pottsville coal zones are confining units that protect shallow aquifers from injection operations at reservoir depth. DFN models are powerful tools for the simulation and analysis of fracture networks and can play an important role in the assessment of risks associated with carbon sequestration and enhanced coalbed methane recovery. Importantly, the stochastic nature DFN models dictates that they cannot be used to precisely reproduce reservoir conditions in a specific field area. Rather, these models are most useful for simulating the fundamental geometric and statistical properties of fracture networks. Because the specifics of fracture architecture in a given area can be uncertain, multiple realizations of DFN models and DFN-based flow models can help define variability that may be encountered during field operations. Using this type of approach, modelers can inform the risk assessment process by characterizing the types and variability of fracture architecture that may exist in geologic carbon sinks containing natural fractures.
Jack Pashin; Guohai Jin; Chunmiao Zheng; Song Chen; Marcella McIntyre
Definition: Fault Current Limiter | Open Energy Information
Limiter Limiter Jump to: navigation, search Dictionary.png Fault Current Limiter A fault current limiter prevents current in an electrical circuit from exceeding a predetermined level by increasing the electrical impedance of that circuit before the current through the circuit exceeds that level. Fault current limiters are designed so as to minimize the impedance of the circuit under normal conditions to reduce losses, but increase the impedance of the circuit under fault conditions to limit fault current.[1] View on Wikipedia Wikipedia Definition A Fault Current Limiter (FCL) is a device which limits the prospective fault current when a fault occurs (e.g. in a power transmission network). The term includes superconducting devices and non-superconducting devices, however some of the more simple non-superconducting devices (such
Definition: Fault Current Limiting | Open Energy Information
Limiting Limiting Jump to: navigation, search Dictionary.png Fault Current Limiting Fault current limiting can be achieved through sensors, communications, information processing, and actuators that allow the utility to use a higher degree of network coordination to reconfigure the system to prevent fault currents from exceeding damaging levels. Fault current limiting can also be achieved through the implementation of special stand alone devices known as Fault Current Limiters (FCLs) which act to automatically limit high through currents that occur during faults.[1] Related Terms fault, fault current limiter References ↑ SmartGrid.gov 'Description of Functions' Temp LikeLike UnlikeLike You like this.Sign Up to see what your friends like. late:ISGANAttributionsmart grid,smart grid,smart grid,smart grid,
Quaternary faulting of Deschutes County, Oregon.
??Sixty-one normal faults were identified in a 53-kilometer long by 21-kilometer wide northwest-trending zone in central and northern Deschutes County, Oregon. The faults are within� (more)
Wellik, John M.
Fault diagnosis and fault tolerant control using set-membership approaches: Application to real case studies
This paper reviews the use of set-membership methods in fault diagnosis (FD) and fault tolerant control (FTC). Setmembership methods use a deterministic unknown-but-bounded description of noise and parametric uncertainty (interval ... Keywords: Fault Detection, Fault-Tolerant Control, Interval Models, Robustness, Set-Membership
Vicen� Puig
Application of Control Charts for Detecting Faults in Variable ...
... where Tzone = zone temperature, CSP = cooling setpoint ... Fault Implementation and Impact To test ... fault imple- mentations and impacts are provided ...
Locating an active fault zone in Coso geothermal field by analyzing seismic guided waves from microearthquake data
Active fault systems usually provide high-permeability channels for hydrothermal outflow in geothermal fields. Locating such fault systems is of a vital importance to plan geothermal production and injection drilling, since an active fault zone often acts as a fracture-extensive low-velocity wave guide to seismic waves. We have located an active fault zone in the Coso geothermal field, California, by identifying and analyzing a fault-zone trapped Rayleigh-type guided wave from microearthquake data. The wavelet transform is employed to characterize guided-wave's velocity-frequency dispersion, and numerical methods are used to simulate the guided-wave propagation. The modeling calculation suggests that the fault zone is {approx} 200m wide, and has a P wave velocity of 4.80 km/s and a S wave velocity of 3.00 km/s, which is sandwiched between two half spaces with relatively higher velocities (P wave velocity 5.60 km/s, and S wave velocity 3.20 km/s). zones having vertical or nearly vertical dipping fault planes.
Distribution Fault Location and Waveform Characterization
Automated fault location algorithms for distribution systems require monitoring equipment to record voltage and current waveforms during an event. In addition, most of these algorithms require circuit-impedance parameters to evaluate the fault location. Locating incipient faults and fault waveform characterization is the main aim of this project. This project builds on work done in 2008 towards sub-cycle blip identification using an algorithm based on arc voltage.
Benchmarking of Fault-Location Technologies
This report resumes the studies on fault-location technologies that were conducted in 2009. These studies were undertaken in a joint project done with the collaboration of Hydro-Qubec, Long Island Power Authority, and the Electric Power Research Institute (EPRI). Two fault-location technologies were tested, the Reactance to Fault (RTF) implemented in the PQView application and the Voltage Drop Fault Location (VDFL) implemented in the MILE application. The RTF is based on substation voltage and current me...
Fault detection and diagnosis of technical systems
Sensors, actuators and/or physical components in technical systems are often affected by unpermitted or un-expected deviations from normal operation behaviour. The fault diagnosis task consists of determination of the fault type with as many details ... Keywords: fault detection and diagnosis, residuals, symptoms, technical systems
Ioana Fagarasan; S. ST. Iliescu
CRT RSA algorithm protected against fault attacks
Embedded devices performing RSA signatures are subject to Fault Attacks, particularly when the Chinese Remainder Theorem is used. In most cases, the modular exponentiation and the Garner recombination algorithms are targeted. To thwart Fault Attacks, ... Keywords: RSA, chinese remainder theorem, fault attacks, modular exponentiation, simple power analysis, smart card
Arnaud Boscher; Robert Naciri; Emmanuel Prouff
High temperature superconducting fault current limiter
A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.
Hull, J.R.
Autonomic fault mitigation in embedded systems
Autonomy, particularly from a maintenance and fault-management perspective, is an increasingly desirable feature in embedded (and non-embedded) computer systems. The driving factors are several-including increasing pervasiveness of computer systems, ... Keywords: Autonomic computing, Embedded systems, Fault mitigation, Fault tolerance, Hierarchical concurrent finite-state machines, Model-based design
Sandeep Neema; Ted Bapty; Shweta Shetty; Steven Nordstrom
Designing Fault-Tolerant Mobile Systems
The purpose of this paper is to investigate how several innovative techniques, not all initially intended for fault-tolerance, can be applied in providing fault tolerance of complex mobile agent systems. Due to their roaming nature, mobile agents usually ... Keywords: exception handling, fault tolerance, mobile agents, software engineering, system structuring
Giovanna Di Marzo Serugendo; Alexander B. Romanovsky
A Physically Based Approach for Modeling Multiphase Fracture-Matrix Interaction in Fractured Porous Media
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
A physically based numerical approach for modeling fracture-matrix interaction in fractured reservoirs
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
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
Correlating laboratory observations of fracture mechanical properties to hydraulically-induced microseismicity in geothermal reservoirs.
To date, microseismicity has provided an invaluable tool for delineating the fracture network produced by hydraulic stimulation of geothermal reservoirs. While the locations of microseismic events are of fundamental importance, there is a wealth of information that can be gleaned from the induced seismicity (e.g. fault plane solutions, seismic moment tensors, source characteristics). Closer scrutiny of the spatial and temporal evolution of seismic moment tensors can shed light on systematic characteristics of fractures in the geothermal reservoir. When related to observations from laboratory experiments, these systematic trends can be interpreted in terms of mechanical processes that most likely operate in the fracture network. This paper reports on mechanical properties that can be inferred from observations of microseismicity in geothermal systems. These properties lead to interpretations about fracture initiation, seismicity induced after hydraulic shut-in, spatial evolution of linked fractures, and temporal evolution of fracture strength. The correlations highlight the fact that a combination of temperature, stressing rate, time, and fluid-rock interactions can alter the mechanical and fluid transport properties of fractures in geothermal systems.
Vertical movement along the Cerro Prieto transform fault, Baja California, Mexico - a mechanism for geothermal energy renewal
Data from 53 geothermal wells to depths of 1 to 3 km on either side of the right-lateral Cerro Prieto fault, as well as geophysical data, indicate vertical displacements of this fault of 400 to 600 m. This episoidic vertical movement has offset deltaic sandstone reservoirs that are primarily at 1200 m and 1800 m depth and contain 250{sup 0} to 345{sup 0}C water. A major fracture system for convective fluid movement has been thus maintained, with production at 150 MW.
Vonder Haar, S.; Noble, J.E.; Puente Cruz, I.
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)
Uncertainty in the maximum principal stress estimated from hydraulic fracturing Measurements due to the presence of the induced fracture
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
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.
Practical simulation of hierarchical brittle fracture
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
Limitations for detecting small-scale faults using the coherency analysis of seismic data
Coherency analyzes the trace to trace amplitude similarities recorded by seismic waves. Coherency algorithms have been used to identify the structural or stratigraphic features of an area but the limitations for detecting small-scale features are not known. These limitations become extremely important when interpreting coherency within poorly acquired or processed data sets. In order to obtain a better understanding of the coherency limitations, various synthetic seismic data sets were created. The sensitivity of the coherency algorithms to variations in wave frequency, signal-to-noise ratio and fault throw was investigated. Correlation between the coherency values of a faulted reflector and the known offset shows that coherency has the ability to detect the presence of various scale features that may be previously thought to be below seismic resolution or difficult to discriminate with conventional interpretation methods. Coherency values had a smaller standard deviation and were less sensitive to noise when processed with a temporal window length less than one period. A fault could be detected by coherency when the signal-to-noise ratio was >3. A fault could also be detected as long as the throw-to-wavelength ratio was >5% or two-way traveltime-toperiod >10%. Therefore, this study suggests that coherency has the ability to detect a fault as long as the frequency of the data imaging that fault has a period no greater than one order of magnitude to the traveltime through the fault and that the signal can easily be distinguished from noise. Results from application of the coherency analysis were applied to the characterization of a very deep fault and fracture system imaged by a field seismic data set. A series of reverse and strike-slip faults were detected and mapped. Magnitudes of the throws for these faults were not known, but subtle amplitude anomalies in seismic sections confirmed the coherency analysis. The results of this study suggest that coherency has demonstrated an ability to detect features that would normally beoverlooked using traditional interpretation methods and has many future implications for poorly imaged seismic areas, such as sub-salt.
Barnett, David Benjamin
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
Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System
To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ({sup 3}He/{sup 4}He) of 0.1-2.5 times the ratio in air, indicating that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault (Kennedy et al., 1997). Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C- and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and deformation zones follows that shown by carbonates in host limestones, marbles, and other host rocks, increasing with increasing contribution of deep metamorphic crustal volatiles. At each crustal level, the composition of the infiltrating fluids is thus buffered by deeper metamorphic sources. A negative correlation between calcite {delta}{sup 13}C and fluid inclusion {sup 3}He/{sup 4}He is consistent with a mantle origin for a fraction of the infiltrating CO{sub 2}. Noble gas and stable isotope systematics show consistent evidence for the involvement of mantle-derived fluids combined with infiltration of deep metamorphic H{sub 2}O and CO{sub 2} in faulting, supporting the involvement of deep fluids percolating through and perhaps weakening the fault zone. There is no clear evidence for a significant contribution from meteoric water, except for overprinting related to late weathering.
Pili, E.; Kennedy, B.M.; Conrad, M.E.; Gratier, J.-P.
Fault-ignorant Quantum Search
We investigate the problem of quantum searching on a noisy quantum computer. Taking a 'fault-ignorant' approach, we analyze quantum algorithms that solve the task for various different noise strengths, which are possibly unknown beforehand. We prove lower bounds on the runtime of such algorithms and thereby find that the quadratic speedup is necessarily lost (in our noise models). However, for low but constant noise levels the algorithms we provide (based on Grover's algorithm) still outperform the best noiseless classical search algorithm.
Peter Vrana; David Reeb; Daniel Reitzner; Michael M. Wolf
A power control and fault detectcr circuit for a radiofrequency system is described. The operation of the circuit controls the power output of a radio- frequency power supply to automatically start the flow of energizing power to the radio-frequency power supply and to gradually increase the power to a predetermined level which is below the point where destruction occurs upon the happening of a fault. If the radio-frequency power supply output fails to increase during such period, the control does not further increase the power. On the other hand, if the output of the radio-frequency power supply properly increases, then the control continues to increase the power to a maximum value. After the maximumn value of radio-frequency output has been achieved. the control is responsive to a ''fault,'' such as a short circuit in the radio-frequency system being driven, so that the flow of power is interrupted for an interval before the cycle is repeated.
Winningstad, C.N.
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.
Faulting in the Yucca Mountain region: Critical review and analyses of tectonic data from the central Basin and Range
Yucca Mountain, Nevada, has been proposed as the potential site for a high-level waste (HLW) repository. The tectonic setting of Yucca Mountain presents several potential hazards for a proposed repository, such as potential for earthquake seismicity, fault disruption, basaltic volcanism, magma channeling along pre-existing faults, and faults and fractures that may serve as barriers or conduits for groundwater flow. Characterization of geologic structures and tectonic processes will be necessary to assess compliance with regulatory requirements for the proposed high level waste repository. In this report, we specifically investigate fault slip, seismicity, contemporary stain, and fault-slip potential in the Yucca Mountain region with regard to Key Technical Uncertainties outlined in the License Application Review Plan (Sections 126.96.36.199 through 184.108.40.206 and 22.214.171.124). These investigations center on (i) alternative methods of determining the slip history of the Bare Mountain Fault, (ii) cluster analysis of historic earthquakes, (iii) crustal strain determinations from Global Positioning System measurements, and (iv) three-dimensional slip-tendency analysis. The goal of this work is to assess uncertainties associated with neotectonic data sets critical to the Nuclear Regulatory Commission and the Center for Nuclear Waste Regulatory Analyses` ability to provide prelicensing guidance and perform license application review with respect to the proposed HLW repository at Yucca Mountain.
Ferrill, D.A.; Stirewalt, G.L.; Henderson, D.B.; Stamatakos, J.; Morris, A.P.; Spivey, K.H. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses; Wernicke, B.P. [California Inst. of Tech., Pasadena, CA (United States). Div. of Geological and Planetary Sciences
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.
Hardware Fault Insertion Techniques and Tools
The concept of dependability validation becomes more and more important regarding big public telecom systems. This is why fault insertion has been widely accepted as a means of testing the fault handling mechanisms of the systems. This master thesis classifies and compares fault insertion techniques used within the industry. It also looks into internal fault insertion techniques used by the people at Ericsson Telecom working with the AXD301 ATM switch. Hardware Fault Insertion Techniques and Tools 2 Acknowledgements The following people at Ericsson has contributed to this thesis in one way or another: Roger Nordmark Mattias Rimbark Bengt Kvist Anders strm Kenny Ohlsson Johan Jeppson Johan Eklv Also a thank you to my supervisor at KTH: Axel Jantsch A special thanks also to my good friend and colleague: Robert Thorhuus Hardware Fault Insertion Techniques and Tools 3 Abbreviations ASIC - Application Specific Integrated Circuit ATM - Asynchronous Transfer Mode BSDL - Boundary Scan De...
Emil Savqvist; Roger Nordmark; Mattias Rimbark; Bengt Kvist; Anders �str�m; Kenny Ohlsson; Johan Ekl�v; Axel Jantsch; Robert Thorhuus; Hw Hard Ware
Meshless animation of fracturing solids
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
and T. W. Keech (1977), Hydraulic fracture mapping usingpotential measurements during hydraulic fracturing of Bunterbetween electrical and hydraulic flow patterns from rock
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
NETL: Discrete Fracture Reservoir Simulation Software
Discrete Fracture Reservoir Simulation FRACGENNFFLOW Shale Gas Flow Simulation Shale Gas Flow Simulation FRACGENNFFLOW, a fractured reservoir modeling software developed by the...
Shale Gas Development Challenges: Fracture Fluids | Department...
Centers Field Sites Power Marketing Administration Other Agencies You are here Home Shale Gas Development Challenges: Fracture Fluids Shale Gas Development Challenges: Fracture...
Fault Current Management Guidebook--Updated
Due to increased load demands and reduced incentives to build new transmission, energy companies are increasing power flows on existing transmission assets, which will increase fault current levels throughout the power system. Also, new generation sources to be added at the transmission and distribution network will increase power flows and, consequently, fault current levels. Under increased power flow conditions on existing assets, managing fault currents is crucial for avoiding damage to equipment as ...
Fault Tree Based Diagnostics Using Fuzzy Logic
Fuzzy set theory is investigated as a tool for the diagnostics of systems described by means of a fault tree. The objective is to diagnose component failures from the observation of fuzzy symptoms using the information contained in a fault tree. A two-step ... Keywords: causal reasoning, component failures, failure analysis, failure modes, fault tree based diagnostics, fuzzy logic, fuzzy symptoms, minimal cut-sets, triggered gates, two-step procedure
P. Gmytrasiewicz; J. A. Hassberger; J. C. Lee
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.
�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
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
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
Fault diagnosis in reversible circuits under missing-gate fault model
This article presents a novel technique for fault detection as well as fault location in a reversible combinational circuit under the missing gate fault model. It is shown that in an (nxn) reversible circuit implemented with k-CNOT gates, addition of ...
Hafizur Rahaman; Dipak K. Kole; Debesh K. Das; Bhargab B. Bhattacharya
Fracturing Fluid Characterization Facility
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
Explosive fracturing method
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.
Seismic detection of fractured Devonian shale reservoir. Annual report, July 1985-June 1986
Interpretation of seismic data over the Cottageville gas field in West Virginia reveals the presence of numerous changes in reflection character across the top of the Lower Huron shales. Production from the Lower Huron is fracture-controlled, and some of the more-pronounced changes in amplitude and shape occur in the more-productive areas of the field. Model studies indicate that these changes are related to the development of low-impedance intervals that extend into the overlying shales of the Middle Huron. Analysis of geophysical logs indicates that these differences are not produced by lithologic variability in the shale. Hence, the observed changes in reflection character are believed to be associated with intense fracturing. Studies here suggest that the analysis of seismic data can be combined with other data to reduce the risk associated with exploration and development of Devonian shale gas resources. Final open-flow of gas and geologic structure from >4000 shale gas wells in eastern Kentucky outlines two high-flow areas. Interrelationships between geologic structure and gas flow are direct in one, but they are complex and unresolved in the other. Linear, steep flow gradients and the interrelationships of high-flow to structure confirm the importance of tectonic fracture permeability to shale productivity.
Wilson, T.H.; Shumaker, R.C.; Sims, C.S.
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
Distribution Fault Location Support Tools, Algorithms, and Implementation Approaches
Distribution grid modernization applications such as fault location and automatic sectionalizing require an accurate assessment of fault current. More-accurate prediction of fault locations will shorten the fault investigation (patrol) time, which in turn can reduce the total restoration time and duration of the outage experienced by the customer. This EPRI technical update report presents information on fault location applications, enumerates different methods used to detect the location of faults, ...
ARMor: fully verified software fault isolation
We have designed and implemented ARMor, a system that uses software fault isolation (SFI) to sandbox application code running on small embedded processors. Sandboxing can be used to protect components such as the RTOS and critical control loops from ... Keywords: arm executables, automated theorem proving, program logic, software fault isolation
Lu Zhao; Guodong Li; Bjorn De Sutter; John Regehr
A switch level fault simulation environment
This paper presents a fault simulation environment which accepts pure switch level or mixed switch/RT level descriptions of the design under test. Switch level fault injection strategies for the stuck-at, transition and logic bridge models are presented. ...
V. Krishnaswamy; J. Casas; T. Tetzlaff
Numeric simulation of faults in electrical networks
In the paper is presented a virtual simulator for three-phased medium voltage electric circuits. The simulator allows analyzing transient regimes caused by the faults produced in electric distribution networks (simple grounding, double grounding, broken ... Keywords: faults in electric network, numerical simulation, three phased circuits, transient regimes
Toader Dumitru; Haragus Stefan; Blaj Constantin
Gas Turbine Fault Diagnosis using Random Forests
In the present paper, Random Forests are used in a critical and at the same time non trivial problem concerning the diagnosis of Gas Turbine blading faults, portraying promising results. Random forests-based fault diagnosis is treated as a Pattern Recognition ...
Manolis Maragoudakis; Euripides Loukis; Panayotis-Prodromos Pantelides
BASE: Using abstraction to improve fault tolerance
Software errors are a major cause of outages and they are increasingly exploited in malicious attacks. Byzantine fault tolerance allows replicated systems to mask some software errors but it is expensive to deploy. This paper describes a replication ... Keywords: Byzantine fault tolerance, N-version programming, asynchronous systems, proactive recovery, state machine replication
Miguel Castro; Rodrigo Rodrigues; Barbara Liskov
Representing parameterised fault trees using Bayesian networks
Fault trees are used to model how failures lead to hazards and so to estimate the frequencies of the identified hazards of a system. Large systems, such as a rail network, do not give rise to endless different hazards. Rather, similar hazards arise repeatedly ... Keywords: Bayesian network, fault tree, risk analysis
William Marsh; George Bearfield
INDUCTION MOTOR FAULT DIAGNOSTIC AND MONITORING METHODS by Aderiano M. da Silva, B.S. A Thesis;i Abstract Induction motors are used worldwide as the "workhorse" in industrial applications material. However, induction motor faults can be detected in an initial stage in order to prevent
Povinelli, Richard J.
fault diagnosis of a high voltage transmission line using waveform ...
Oct 4, 2013 ... FAULT DIAGNOSIS OF A HIGH VOLTAGE TRANSMISSION LINE USING ... Fault types such as single line to ground, line to line, double line to�...
Modeling and Measurement Constraints in Fault Diagnostics for HVAC Systems
in Fault Diagnostics for HVAC Systems Massieh Najafi 1 ,tools for determining HVAC diagnostics, methods todetect faults in HVAC systems are still generally
Najafi, Massieh
Modeling and simulation of HVAC faults in EnergyPlus
simulation of HVAC faults in EnergyPlus Title Modeling and simulation of HVAC faults in EnergyPlus Publication Type Conference Paper Refereed Designation Refereed Year of...
Modeling and Measurement Constraints in Fault Diagnostics for...
Modeling and Measurement Constraints in Fault Diagnostics for HVAC Systems Title Modeling and Measurement Constraints in Fault Diagnostics for HVAC Systems Publication Type Journal...
CIFTS: Coordinated Infrastructure for Fault-Tolerant Systems...
CIFTS: Coordinated Infrastructure for Fault-Tolerant Systems CIFTS: Coordinated Infrastructure for Fault-Tolerant Systems Current systems software components for large-scale...
CIFTS: A Coordinated Infrastructure for Fault-Tolerant Systems...
CIFTS: A Coordinated Infrastructure for Fault-Tolerant Systems Title CIFTS: A Coordinated Infrastructure for Fault-Tolerant Systems Publication Type Conference Paper Year of...
Detect and classify faults using neural nets
The analysis of transmission line faults is essential to the proper performance of the power system. It is required if protective relays are to take the appropriate action and in monitoring the performance of relays, circuit breakers, and other protective and control elements. The detection and classification of transmission line faults is a fundamental component of such fault analysis. Another application of fault analysis is in software packages for automated analysis of digital fault recorder (DFR) files. Recently, such a package, called DFR Assistant, was developed for substation applications. This program can be installed locally in a substation, in which case it is connected directly to the DFR via a high speed parallel link, or it can be installed at a central station, in which case it can be configured to automatically analyze events coming from all DFRs.
Kezunovic, M.; Rikalo, I.
Automated Fault Location In Smart Distribution Systems
Fault location in distribution systems is a critical component of outage management and service restoration, which directly impacts feeder reliability and quality of the electricity supply. Improving fault location methods supports the Department of Energy (DOE) �Grid 2030� initiatives for grid modernization by improving reliability indices of the network. Improving customer average interruption duration index (CAIDI) and system average interruption duration index (SAIDI) are direct advantages of utilizing a suitable fault location method. As distribution systems are gradually evolving into smart distribution systems, application of more accurate fault location methods based on gathered data from various Intelligent Electronic Devices (IEDs) installed along the feeders is quite feasible. How this may be done and what is the needed methodology to come to such solution is raised and then systematically answered. To reach this goal, the following tasks are carried out: 1) Existing fault location methods in distribution systems are surveyed and their strength and caveats are studied. 2) Characteristics of IEDs in distribution systems are studied and their impacts on fault location method selection and implementation are detailed. 3) A systematic approach for selecting optimal fault location method is proposed and implemented to pinpoint the most promising algorithms for a given set of application requirements. 4) An enhanced fault location method based on voltage sag data gathered from IEDs along the feeder is developed. The method solves the problem of multiple fault location estimations and produces more robust results. 5) An optimal IED placement approach for the enhanced fault location method is developed and practical considerations for its implementation are detailed.
Lotfifard, Saeed
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-
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
Determining the 3-D fracture structure in the Geysers geothermal reservoir
The bulk of the steam at the Geysers geothermal field is produced from fractures in a relatively impermeable graywacke massif which has been heated by an underlying felsite intrusion. The largest of these fractures are steeply dipping right lateral strike-slip faults which are subparallel to the NW striking Collayomi and Mercuryville faults which form the NE and SW boundaries of the known reservoir. Where the graywacke source rock outcrops at the surface it is highly sheared and fractured over a wide range of scale lengths. Boreholes drilled into the reservoir rock encounter distinct ''steam entries'' at which the well head pressure jumps from a few to more than one hundred psi. This observation that steam is produced from a relatively small number of major fractures has persuaded some analysts to use the Warren and Root (1963) dual porosity model for reservoir simulation purposes. The largest fractures in this model are arranged in a regular 3-D array which partitions the reservoir into cubic ''matrix'' blocks. The net storage and transport contribution of all the smaller fractures in the reservoir are lumped into average values for the porosity and permeability of these matrix blocks which then feed the large fractures. Recent improvements of this model largely focus on a more accurate representation of the transport from matrix to fractures (e.g. Pruess et al., 1983; Ziminerman et al., 1992), but the basic geometry is rarely questioned. However, it has long been recognized that steam entries often occur in clusters separated by large intervals of unproductive rock (Thomas et al., 1981). Such clustering of fixtures at all scale lengths is one characteristic of self-similar distributions in which the fracture distribution is scale-independent. Recent studies of the geometry of fracture networks both in the laboratory and in the field are finding that such patterns are self-similar and can be best described using fractal geometry. Theoretical simulations of fracture development in heterogeneous media also produce fractal patterns. However, a physical interpretation of the mechanics which produce the observed fractal geometry remains an active area of current research. Two hypotheses for the physical cause of self-similarity are the Laplacian growth of fractures in a self-organized critical stress field, and the evolution of percolation clusters in a random medium. Each predicts a different, fractal dimension. The more important questions from a reservoir engineering point of view are: (1) is the network of fractures in the Geysers reservoir fractal and if so over what range of fracture sizes is the self-similarity observed and what is its fractal dimension, and (2) do the conventional dual porosity numerical simulation schemes provide an adequate description of flow and heat mining at the Geysers? Other papers in this volume by Acuna, Ershaghi, and Yortsos (1992) and Mukhopodhyoy and Sahimi (1992) address the second question. The primary objective of this paper is to try to answer the first. Toward this goal we have mapped fracture patterns in surface exposures of the graywacke source rock at the outcrop scale (meters), at the road-cut scale (tens of meters) and at the regional scale (kilometers). We have also examined cores collected at depth from the graywacke reservoir rocks, and analyzed drilling logs making use of the pattern of steam entries as well as the fluctuations in drilling rate.
Sammis, Charles G.; Linji An; Iraj Ershaghi
Ductile Fracture Handbook: Volume 2
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
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...
Fault diagnosis using substation computer
A number of substation integrated control and protection systems (ICPS) are being developed around the world, where the protective relaying, control, and monitoring functions of a substation are implemented using microprocessors. In this design, conventional relays and control devices are replaced by clusters of microprocessors, interconnected by multiplexed digital communication channels using fibre optic, twisted wire pairs or coaxial cables. The ICPS incorporates enhanced functions of value to the utility and leads to further advancement of the automation of transmission substations. This paper presents an automated method of fault diagnosis which can be incorporated in the station computer of an integrated control and protection system. The effectiveness of this method is demonstrated using a transmission-level substation as an example.
Jeyasurya, B. (Indian Inst. of Tech., Bombay (India)); Venkata, S.S. (Washington Univ., Seattle, WA (USA). Dept. of Electrical Engineering); Vadari, S.V. (ESCA Corp., Bellevue, WA (USA)); Postforoosh, J. (T and D. Protection Group, Puget Sound Power and Light, Bellevue, WA (US))
An arc fault detection system
An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn, opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard.
Jha, Kamal N.
Natural time analysis of critical phenomena: The case of pre-fracture electromagnetic emissions
Criticality of complex systems reveals itself in various ways. One way to monitor a system at critical state is to analyze its observable manifestations using the recently introduced method of natural time. Pre-fracture electromagnetic (EM) emissions, in agreement to laboratory experiments, have been consistently detected in the MHz band prior to significant earthquakes. It has been proposed that these emissions stem from the fracture of the heterogeneous materials surrounding the strong entities (asperities) distributed along the fault, preventing the relative slipping. It has also been proposed that the fracture of heterogeneous material could be described in analogy to the critical phase transitions in statistical physics. In this work, the natural time analysis is for the first time applied to the pre-fracture MHz EM signals revealing their critical nature. Seismicity and pre-fracture EM emissions should be two sides of the same coin concerning the earthquake generation process. Therefore, we also examine the corresponding foreshock seismic activity, as another manifestation of the same complex system at critical state. We conclude that the foreshock seismicity data present criticality features as well.
Potirakis, S. M. [Department of Electronics, Technological Education Institute (TEI) of Piraeus, 250 Thivon and P. Ralli, Aigaleo, Athens GR-12244 (Greece)] [Department of Electronics, Technological Education Institute (TEI) of Piraeus, 250 Thivon and P. Ralli, Aigaleo, Athens GR-12244 (Greece); Karadimitrakis, A. [Department of Physics, Section of Electronics, Computers, Telecommunications and Control, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece)] [Department of Physics, Section of Electronics, Computers, Telecommunications and Control, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece); Eftaxias, K. [Department of Physics, Section of Solid State Physics, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece)] [Department of Physics, Section of Solid State Physics, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece)
Cooperative application/OS DRAM fault recovery.
Exascale systems will present considerable fault-tolerance challenges to applications and system software. These systems are expected to suffer several hard and soft errors per day. Unfortunately, many fault-tolerance methods in use, such as rollback recovery, are unsuitable for many expected errors, for example DRAM failures. As a result, applications will need to address these resilience challenges to more effectively utilize future systems. In this paper, we describe work on a cross-layer application/OS framework to handle uncorrected memory errors. We illustrate the use of this framework through its integration with a new fault-tolerant iterative solver within the Trilinos library, and present initial convergence results.
Ferreira, Kurt Brian; Bridges, Patrick G. (University of New Mexico, Albuquerque, NM); Heroux, Michael Allen; Hoemmen, Mark; Brightwell, Ronald Brian
Mechanical Models of Fault-Related Folding
The subject of the proposed research is fault-related folding and ground deformation. The results are relevant to oil-producing structures throughout the world, to understanding of damage that has been observed along and near earthquake ruptures, and to earthquake-producing structures in California and other tectonically-active areas. The objectives of the proposed research were to provide both a unified, mechanical infrastructure for studies of fault-related foldings and to present the results in computer programs that have graphical users interfaces (GUIs) so that structural geologists and geophysicists can model a wide variety of fault-related folds (FaRFs).
Johnson, A. M.
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
The Essential Work of Fracture Method Applied to Mode II Interlaminar Fracture in Fiber Reinforced Polymers.
??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 fracture optimization using hydraulic fracture and reservoir modeling in the Piceance Basin, Colorado.
??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
Neural Fault Diagnosis and Fuzzy Fault Control for a Complex Dynamic System
Fault diagnosis has become an issue of primary importance in modern process automation as it provides the prerequisites for the task of fault detection. The ability to detect the faults is essential to improve reliability and security of a complex control system. Parameter estimation methods, state observation schemes, statistical likelihood ratio tests, rule-based expert system reasoning, pattern recognition techniques, and artificial neural network approaches are the most common methodologies developed actively during recent years. In this paper, we describe a completed feasibility study demonstrating the merit of employing pattern recognition and an artificial neural network for fault diagnosis through back propagation learning algorithm and making the use of fuzzy approximate reasoning for fault control via parameter changes in a dynamic system. As a test case, a complex magnetic levitation vehicle (MLV) system is studied. Analytical fault symptoms are obtained by system dynamics m...
Ching-yu Tyan; Paul P. Wang; Dennis R. Bahler
Quantification of Priority-OR gates in temporal fault trees
Fault Tree Analysis has been used in reliability engineering for many decades and has seen various modifications to enable it to analyse fault trees with dynamic and temporal gates so it can incorporate sequential failure in its analysis. Pandora is ... Keywords: Markov chains, Monte Carlo, Pandora, dynamic fault trees, fault trees, safety
Ernest Edifor; Martin Walker; Neil Gordon
A transmission line fault locator based on Elman recurrent networks
In this paper, a transmission line fault location model which is based on an Elman recurrent network (ERN) has been presented for balanced and unbalanced short circuit faults. All fault situations with different inception times are implemented on a 380-kV ... Keywords: Elman networks, Fault location, Transmission lines, Wavelet transform
Sami Ekici; Selcuk Yildirim; Mustafa Poyraz
Development of Hydrologic Characterization Technology of Fault Zones
pathways in the Monterey Formation, California: Americanalong faults in the Monterey Formation, coastal California.
Karasaki, Kenzi
Online fault detection and tolerance for photovoltaic energy harvesting systems
Photovoltaic energy harvesting systems (PV systems) are subject to PV cell faults, which decrease the efficiency of PV systems and even shorten the PV system lifespan. Manual PV cell fault detection and elimination are expensive and nearly impossible ... Keywords: fault detection, fault tolerance, photovoltaic panel reconfiguration, photovoltaic system
Xue Lin; Yanzhi Wang; Di Zhu; Naehyuck Chang; Massoud Pedram
Hydrogen-Assisted Fracture: Materials Testing and Variables Governing Fracture
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
Characterization of Fracture Patterns in the Geysers Geothermal Reservoir by Shear-wave Splitting
The authors have analyzed the splitting of shear waves from microearthquakes recorded by a 16-station three-component seismic network at the Northwest Geysers geothermal field, Geysers, California, to determine the preferred orientation of subsurface fractures and cracks. Average polarization crack directions with standard deviation were computed for each station. Also, graphical fracture characterizations in the form of equal-area projections and rose diagrams were created to depict the results. The main crack orientations within the steam field are predominantly in the N10{degree}E to N50{degree}E direction, consistent with expected fracture directions in a pull-apart basin created by sub-parallel right-lateral strike-slip faults related to the San Andreas fault system. Time delays range from 15--60 ms, similar to the time delays from previous studies at geothermal reservoirs. They have detected a significant increase in time delays between 1988 and 1994, which they attribute to widening of the cracks or filling of the cracks with fluid. Increase in production activities during this time also could have influenced this widening.
D. Erten; J. A. Rial
Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997
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.
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
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
modeling fluid and heat flow in fractured porous media, Soc.fluid flow, multicomponent transport, and heat transfer in porous and fractured media,fluid flow, solute transport, and heat transfer occur in porous and fractured media.
Fault intersections and hybrid transform faults in the southern Salton Trough geothermal area, Baja California, Mexico
Analysis of 55 wells drilled at the Cerro Prieto Geothermal Field and a suite of geological and geophysical studies throughout the southern Salton Trough from the Mexican-United States border to the Gulf of California clarify two concepts important to geothermal development: (1) increased natural convective fluid flow and better permeability should occur at intersecting faults both regionally and within a producing field, and (2) the Cerro Prieto and Imperial faults are best conceived of as hybrid types having features of both San Andreas style wrench faults and oceanic tranform faults.
Vonder Haar, S.; Puente Cruz, I.
Fault Detection, Location, Isolation and Reconnection in ...
A University of Colorado research team led by Jae-Do Park has developed a fault detection, location and isolation scheme for a low-voltage DC-bus microgrid system, ...
Fault tolerance for holonomic quantum computation
We review an approach to fault-tolerant holonomic quantum computation on stabilizer codes. We explain its workings as based on adiabatic dragging of the subsystem containing the logical information around suitable loops along which the information remains protected.
Ognyan Oreshkov; Todd A. Brun; Daniel A. Lidar
Image Logs | Open Energy Information
Image Logs Image Logs Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Image Logs Details Activities (2) Areas (1) 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, grain size, mineral, and clay content Stratigraphic/Structural: -Fault and fracture identification -Rock texture, porosity, and stress analysis -determine dip, thickness, and geometry of rock strata in vicinity of borehole -Detection of permeable pathways, fracture zones, faults Hydrological: Locate zones of aquifer inflow/outflow Thermal:
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
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)
Seismic studies of a massive hydraulic fracturing experiment
During a massive hydraulic fracturing experiment carried out at Fenton Hill, New Mexico, 850 microearthquakes, ranging in magnitudes from -3 to 0, were located reliably using arrival times recorded at a set of 5 downhole geophone stations. A subset of these events were located using an upgraded hodogram technique. The seismicity defines a tabular zone with horizontal extent of 900 m, vertical extent of 800 m, and thickness of 150 m. This zone strikes N340/sup 0/E, and dips 75/sup 0/ to the east; its position indicates that no hydraulic connection between the two predrilled wells could be achieved by the fracturing. The distribution of locations obtained from arrival times shows good agreement with those derived from hodograms. Well constrained fault plane solutions were determined for 26 of the larger microearthquakes observed at a surface seismic net. Most solutions display one nearly vertical nodal plane that strikes close to N - S, and a T axis that trends roughly E - W, in agreement with regional indicators of the least principal stress direction. 9 refs., 6 figs.
House, L.; Keppler, H.; Kaieda, H.
Dolomitization and dedolomitization models in a fractured reservoir, Reed City oil field, Michigan
Hydrocarbon production in the Michigan basin is essentially from pinnacle reefs or fractured reservoirs. The epigenetically formed porous dolomite reservoir rock is intimately related to the shear faults (channelways for rising high Mg/Ca ratio fluids) and to the resulting shear folds, the latter showing dolomite/calcite ratios increasing generally from outer closure to the fold axes. The Reed City field (anticline) of western Michigan represents a dramatic exception to this picture with the dolomite/calcite ratio increasing from outer closure to maximum part way up the limbs then decreasing to the axis. This lowest zone is the only unit not dedolomitized, a fact perhaps commensurate with its low stratigraphic position at the bottom of (and apparently beyond the reach of) the descending high-calcium, low-magnesium waters what brought about the dedolomitization. The dedolomitization model would call for a shallow water to exposed oxidizing environment, possible with the position of this area astride the West Michigan Barrier that separates a lagoonal facies from a more open sea facies to the east. Thus, waters with a high Ca/Mg ratio passed down the same shear faults that earlier were channelways for the rising high Mg/Ca ratio waters. On the bases of isopach, structure and dolomite/calcite (Isodol) maps, one can piece together a reasonably chronological sequence of pre-Dundee shear faulting and folding, post-Traverse upward migration of dolomitizing fluids, upward migration of hydrocarbons along the shear faults, downward-moving dedolomitizing fluids, and a later episode of faulting (especially shear cross-faults).
Carlton, R.R.; Prouty, C.E.
and radiation in a multiphase, multicomponent, porous mediumin modeling multiphase flow in porous and fractured media,phase and multiphase non-Darcy flow in porous and fractured
Development of a Neutron Diffraction Based Experiemental Capability for Investigating Hydraulic Fracturing for EGS-like Conditions
Hydraulic fracturing to enhance formation permeability is an established practice in the Oil & Gas (O&G) industry and is expected to be an enabler for EGS. However, it is rarely employed in conventional geothermal systems and there are significant questions regarding the translation of practice from O&G to both conventional geothermal and EGS applications. Lithological differences(sedimentary versus crystalline rocks, significantly greater formation temperatures and different desired fracture characteristics are among a number of factors that are likely to result in a gap of understanding of how to manage hydraulic fracturing practice for geothermal. Whereas the O&G community has had both the capital and the opportunity to develop its understanding of hydraulic fracturing operations empirically in the field as well through extensive R&D efforts, field testing opportunities for EGS are likely to be minimal due to the high expense of hydraulic fracturing field trials. A significant portion of the knowledge needed to guide the management of geothermal/EGS hydraulic fracturing operations will therefore likely have to come from experimental efforts and simulation. This paper describes ongoing efforts at Oak Ridge National Laboratory (ORNL) to develop an experimental capability to map the internal stresses/strains in core samples subjected to triaxial stress states and temperatures representative of EGS-like conditions using neutron diffraction based strain mapping techniques. This capability is being developed at ORNL\\'s Spallation Neutron Source, the world\\'s most powerful pulsed neutron source and is still in a proof of concept phase. A specialized pressure cell has been developed that permits independent radial and axial fluid pressurization of core samples, with axial flow through capability and a temperature rating up to 300 degrees C. This cell will ultimately be used to hydraulically pressurize EGS-representative core samples to conditions of imminent fracture and map the associated internal strain states of the sample. This will hopefully enable a more precise mapping of the rock material failure envelope, facilitate a more refined understanding of the mechanism of hydraulically induced rock fracture, particularly in crystalline rocks, and serve as a platform for validating and improving fracture simulation codes. The elements of the research program and preliminary strain mapping results of a Sierra White granite sample subjected only to compressive loading will be discussed in this paper.
Polsky, Yarom [ORNL; Anovitz, Lawrence {Larry} M [ORNL; An, Ke [ORNL; Carmichael, Justin R [ORNL; Bingham, Philip R [ORNL; Dessieux Jr, Luc Lucius [ORNL
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.
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.
Dissipative particle dynamics simulation of fluid motion through an unsaturated fracture and fracture junction
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
Summary of Linear Elastic Fracture Mechanics Concepts
...in this Volume."Stress Intensity Factors"A brief summary of linear elastic fracture mechanics (LEFM) concepts
Development of a fixation device for robot assisted fracture reduction of femoral shaft fractures: A biomechanical study
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
Optimizing fracture stimulation using treatment-well tiltmeters and integrated fracture modeling
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)
Measuring and Modeling Fault Density for Plume-Fault Encounter Probability Estimation
Emission of carbon dioxide from fossil-fueled power generation stations contributes to global climate change. Storage of this carbon dioxide within the pores of geologic strata (geologic carbon storage) is one approach to mitigating the climate change that would otherwise occur. The large storage volume needed for this mitigation requires injection into brine-filled pore space in reservoir strata overlain by cap rocks. One of the main concerns of storage in such rocks is leakage via faults. In the early stages of site selection, site-specific fault coverages are often not available. This necessitates a method for using available fault data to develop an estimate of the likelihood of injected carbon dioxide encountering and migrating up a fault, primarily due to buoyancy. Fault population statistics provide one of the main inputs to calculate the encounter probability. Previous fault population statistics work is shown to be applicable to areal fault density statistics. This result is applied to a case study in the southern portion of the San Joaquin Basin with the result that the probability of a carbon dioxide plume from a previously planned injection had a 3% chance of encountering a fully seal offsetting fault.
Jordan, P.D.; Oldenburg, C.M.; Nicot, J.-P.
Fractured shale reservoirs: Towards a realistic model
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)
Mechanical properties and modeling of seal-forming lithologies. Technical progress report No. 3, March 15, 1992--June 14, 1993
Specific goals and accomplishments of this research include: (1) The evaluation of models of salt diaper ascent that involve either power law, dislocation creep as determined experimentally by Horseman et al. (1993) or linear, fluid-assisted creep as reported by Spiers et al. (1988, 1990, 1992). We have compared models assuming these two, experimentally evaluated flow laws and examined the predictions they make regarding diaper incubation periods, ascent velocities, deviatoric stresses and strain rates. (2) The evaluation of the effects of differential loading on the initiation an of salt structures. (3) Examination of the role of basement faults on the initiation and morphologic evolution of salt structures. (4) Evaluation of the mechanical properties of shale as a function of pressure and determination of the nature of its brittle-ductile transition. (5) Evaluation of the mechanical anisotropies of shales with varying concentrations, distributions and preferred orientations of clay. (6) The determination of temperature and ratedependencies of strength for a shale constitutive model that can be used in numerical models that depend on viscous formulations. (7) Determination of the mechanisms of deformation for argillaceous rocks over awide range of conditions. (8) Evaluation of the effects of H{sub 2}O within clay interlayers, as adsorbed surface layers.
A fault location approach for fuzzy fault section estimation on radial distribution feeders
Locating the faulted section of a distribution system is a difficult task because of lack of accurate system models and the presence of uncertainty in the data used for estimating the fault section. Many of the methods used to account for the uncertainty use fuzzy logic techniques to estimate bounds of possibility of the input data and calculated quantities, or probabilistic modeling of the input data to estimate the likelihood of the location of the fault on a particular section of the feeder. Heuristic knowledge of control center dispatchers has also been used for uncertainty management. This thesis presents the design and implementation of a phase selector algorithm and a fault distance algorithm for use in an automated modular scheme for fault section estimation on radial distribution systems. These two algorithms will be executed in combination with two other fault location algorithms. The scheme is executed using the data record of an abnormal event in a three-stage scheme. The phase selector algorithm was used to obtain event-phase possibility values representing the possibility of involvement of each of the phases and the neutral in an event. A section-event possibility value that indicated the possibility that a section of the feeder was involved in the fault was evaluated using the event-phase possibility values and line section phase topology information. The fault distance algorithm was used to eliminate sections of the feeder that were not likely to be possible faulted section candidates by assuming a bolted fault and estimating its location. Each line section was assigned a fault possibility value of zero or one according to its location relative to the location of the fault. The phase selector algorithm was tested using real data measured at feeder substations and the fault distance algorithm was tested using data obtained by staging faults on a model of an overhead feeder using EMTP/ATP simulation. The results obtained from the tests were promising. A simple illustration of the combination of the results of the two algorithms is given. The result of this combination shows the potential of the simultaneous use of the two algorithms.
Andoh, Kwame Sarpong
Fast Fault Recovery in Switched Networks for Carrying IP Telephony Traffic.
?? One of the most parts of VOIP management is fault management and, in having a good fault management, finding good mechanisms to detect faults� (more)
Eisazadeh, Ali Akbar
Fault Locating, Prediction and Protection (FLPPS)
One of the main objectives of this DOE-sponsored project was to reduce customer outage time. Fault location, prediction, and protection are the most important aspects of fault management for the reduction of outage time. In the past most of the research and development on power system faults in these areas has focused on transmission systems, and it is not until recently with deregulation and competition that research on power system faults has begun to focus on the unique aspects of distribution systems. This project was planned with three Phases, approximately one year per phase. The first phase of the project involved an assessment of the state-of-the-art in fault location, prediction, and detection as well as the design, lab testing, and field installation of the advanced protection system on the SCE Circuit of the Future located north of San Bernardino, CA. The new feeder automation scheme, with vacuum fault interrupters, will limit the number of customers affected by the fault. Depending on the fault location, the substation breaker might not even trip. Through the use of fast communications (fiber) the fault locations can be determined and the proper fault interrupting switches opened automatically. With knowledge of circuit loadings at the time of the fault, ties to other circuits can be closed automatically to restore all customers except the faulted section. This new automation scheme limits outage time and increases reliability for customers. The second phase of the project involved the selection, modeling, testing and installation of a fault current limiter on the Circuit of the Future. While this project did not pay for the installation and testing of the fault current limiter, it did perform the evaluation of the fault current limiter and its impacts on the protection system of the Circuit of the Future. After investigation of several fault current limiters, the Zenergy superconducting, saturable core fault current limiter was selected for installation. Because of some testing problems with the Zenergy fault current limiter, installation was delayed until early 2009 with it being put into operation on March 6, 2009. A malfunction of the FCL controller caused the DC power supply to the superconducting magnet to be turned off. This inserted the FCL impedance into the circuit while it was in normal operation causing a voltage resonance condition. While these voltages never reached a point where damage would occur on customer equipment, steps were taken to insure this would not happen again. The FCL was reenergized with load on December 18, 2009. A fault was experienced on the circuit with the FCL in operation on January 14, 2010. The FCL operated properly and reduced the fault current by about 8%, what was expected from tests and modeling. As of the end of the project, the FCL was still in operation on the circuit. The third phase of the project involved the exploration of several advanced protection ideas that might be at a state where they could be applied to the Circuit of the Future and elsewhere in the SCE electrical system. Based on the work done as part of the literature review and survey, as well as a number of internal meetings with engineering staff at SCE, a number of ideas were compiled. These ideas were then evaluated for applicability and ability to be applied on the Circuit of the Future in the time remaining for the project. Some of these basic ideas were implemented on the circuit including measurement of power quality before and after the FCL. It was also decided that we would take what was learned as part of the Circuit of the Future work and extend it to the next generation circuit protection for SCE. Also at this time, SCE put in a proposal to the DOE for the Irvine Smart Grid Demonstration using ARRA funding. SCE was successful in obtaining funding for this proposal, so it was felt that exploration of new protection schemes for this Irvine Smart Grid Demonstration would be a good use of the project resources. With this in mind, a protection system that uses fault interrupting switches, hi
Yinger, Robert, J.; Venkata, S., S.; Centeno, Virgilio
Potential Contaminant Pathways from Hydraulically Fractured Shale to Aquifers. Ground Water. doi: 10.1111/j.1745-6584.2012.00933.x New Hampshire Department of Environmental Services (NHDES). 2010. �Well Development by Hydrofracturing.� http://des.nh.gov/o
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
Method for enhancement of sequential hydraulic fracturing using control pulse fracturing
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.
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
Microseismic Tracer Particles for Hydraulic Fracturing
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
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
VCSEL fault location apparatus and method
An apparatus for locating a fault within an optical fiber is disclosed. The apparatus, which can be formed as a part of a fiber-optic transmitter or as a stand-alone instrument, utilizes a vertical-cavity surface-emitting laser (VCSEL) to generate a test pulse of light which is coupled into an optical fiber under test. The VCSEL is subsequently reconfigured by changing a bias voltage thereto and is used as a resonant-cavity photodetector (RCPD) to detect a portion of the test light pulse which is reflected or scattered from any fault within the optical fiber. A time interval .DELTA.t between an instant in time when the test light pulse is generated and the time the reflected or scattered portion is detected can then be used to determine the location of the fault within the optical fiber.
Keeler, Gordon A. (Albuquerque, NM); Serkland, Darwin K. (Albuquerque, NM)
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.
Evaluation and Effect of Fracturing Fluids on Fracture Conductivity in Tight Gas Reservoirs Using Dynamic Fracture Conductivity Test
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
Geometry of Cenozoic extensional faulting: Dixie Valley, Nevada | Open
Geometry of Cenozoic extensional faulting: Dixie Valley, Nevada Geometry of Cenozoic extensional faulting: Dixie Valley, Nevada Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Geometry of Cenozoic extensional faulting: Dixie Valley, Nevada Abstract Precise definition of geometric relationships between individual basins and ranges may help to reveal the mechanical processes of Basin and Range Cenozoic extensional faulting at depth. Previous studies have attempted to identify simple horsts and grabens, tilted crustal blocks with planar faulting, or tilted crustal blocks with listric faulting in the shallow crust. Normal faults defining these crustal blocks may root (1) individually in the ductile lower crust, (2) in regional or local low-angle detachment faults, or (3) in igneous intrusions or decoupling surfaces
Rough neural fault classification for hvdc power systems
This Ph.D. thesis proposes an approach to classify faults that commonly occur in a High Voltage Direct Current (HVDC) power system. These faults are distributed throughout the entire HVDC system. The most recently published techniques for power system ...
Liting Han
High-level test synthesis for delay fault testability
A high-level test synthesis (HLTS) method targeted for delay fault testability is presented. The proposed method, when combined with hierarchical test pattern generation for embedded modules, guarantees 100% delay test coverage for detectable faults ...
Sying-Jyan Wang; Tung-Hua Yeh
Scalable Distributed Consensus to Support MPI Fault Tolerance
As system sizes increase, the amount of time in which an application can run without experiencing a failure decreases. Exascale applications will need to address fault tolerance. In order to support algorithm-based fault tolerance, communication libraries ...
Darius Buntinas
sensor faults, Energy and Buildings. 42(4). April 2010.faults in buildings. Energy and Buildings. 42(1). Januaryon the DOE-2 model, Energy and Buildings. 21(2). 1994, Pages
Basarkar, Mangesh
Stability of Distributed Algorithms in the Face of Incessant Faults
For large distributed systems built from inexpensive components, one expects to see incessant failures. This paper proposes two models for such faults and analyzes two well-known self-stabilizing algorithms under these fault models. For a small number ...
Robert E. Lee Deville; Sayan Mitra
Synthesis and evaluation of fault-tolerant quantum computer architectures
Fault-tolerance is the cornerstone of practical, large-scale quantum computing, pushed into its prominent position with heroic theoretical efforts. The fault-tolerance threshold, which is the component failure probability ...
Cross, Andrew W. (Andrew William), 1979-
Design and Evaluation of Hybrid Fault-Detection Systems
As chip densities and clock rates increase, processors are becoming more susceptible to transient faults that can affect program correctness. Up to now, system designers have primarily considered hardware-only and software-only fault-detection mechanisms ...
George A. Reis; Jonathan Chang; Neil Vachharajani; Ram Rangan; David I. August; Shubhendu S. Mukherjee
Two-person control administration: preventing administration faults through duplication
Modern computing systems are complex and difficult to administer, making them more prone to system administration faults. Faults can occur simply due to mistakes in the process of administering a complex system. These mistakes can make the system insecure ...
Shaya Potter; Steven M. Bellovin; Jason Nieh
improving production by hydraulic fracturing 8 the focus otfor fractures. (d) Hydraulic Fracturing: The model has been
Wang, J.S.Y.
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.
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
Fault Current Limiters (FCL) Fact Sheet | Department of Energy
& Publications An Assessment of Fault Current Limiter Testing Requirements Superconductivity Program Overview Superconductivity for Electric Systems: 2008 Annual Peer Review...
EPRI Fault Current Management Guidebook, Sixth Edition (Maroon Book)
This document is an update of the document Fault Current Management Guidebook, Fifth Edition on fault current effects and management in transmission and distribution systems. This guide is intended to be a snapshot of available references, information, and literature on the effects of high fault current on a number of power system components and various available and emerging fault-current-limiting technologies.Results and FindingsDue to increased ...
Underground Cable Fault Location Reference and Application Guide
This report summarizes underground cable fault location methods and details the application of the methods for transmission and distribution cable systems. It summarizes both terminal location and tracer location methods that can be applied to transmission and distribution cable systems. The report is an update to a summary of fault location methods. It provides practical technical material in the art and science of locating cable faults, including a description of common fault location instruments and p...
Understanding Fault Characteristics of Inverter-Based Distributed Energy Resources
This report discusses issues and provides solutions for dealing with fault current contributions from inverter-based distributed energy resources.
Keller, J.; Kroposki, B.
Fluid Flow Within Fractured Porous Media
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.
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.
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.
Acoustic Emission in a Fluid Saturated Hetergeneous Porous Layer with Application to Hydraulic Fracture
responses during hydraulic fracturing, and aid developmentFracture Monitoring Hydraulic fracturing is a method forfluids" used for hydraulic fracturing, the above frequencies
Nelson, J.T.
Fault Diagnosis of Transformer Based on Probabilistic Neural Network
In order to improve the correct rate of transformer fault diagnosis based on three-ratio method of traditional dissolved gas analysis (DGA), a novel intelligent transformer fault diagnosis method based on both DGA and probabilistic neural network (PNN) ... Keywords: transformer fault diagnosis, probabilistic neural network (PNN), improved three-ratio method
Li Song; Li Xiu-ying; Wang Wen-xu
New Burnside Anticline: part of Fluorspar area fault complex
Field mapping in the Abbott Formation and examination of topographic lineaments in the Creal Springs, Stonefort, Eddyville, and Harrisburg Quadrangles (southeastern Illinois) reveal the New Burnside anticline and its northeastern extension, the Stonefort anticline to be a single, extensively faulted structure. Interpretation of this evidence also leads to the conclusion that this is a fault-block structure rather than an anticline. Trending notheast-southwest, the structure seems to be the northwesternmost extent of the Fluorspar Area fault complex. The authors found evidence for two episodes of faulting. The first involved northeast-trending, high-angle faults similar to those in the known Fluorspar complex to the southeast. Faults on the northeast (Stonefort antilcine) step down toward the center of the structure, forming a graben. Vertical movement also occurred to the southwest (New Burnside anticline), but the structure in this vicinity is a horst with some blocks tilted. As with other faults in the Fluorspar complex, horizontal slickensides are present locally. The second episode of movement occurred along northwest-southeast-trending strike-slip faults that offset the northeast-trending high-angle faults. This second phase of faulting may correspond with previously reported reactivation of northwest-trending faults elsewhere in the Fluorspar Area fault complex.
Jacobson, R.J.; Trask, C.B.
A lightweight fault tolerance framework for Web services
In this paper, we present the design and implementation of a lightweight fault tolerance framework for Web services. With our framework, a Web service can be rendered fault tolerant by replicating it across several nodes. A consensus-based algorithm ... Keywords: Fault tolerance, Web services, distributed consensus, reliable messaging, replication
Wenbing Zhao; Honglei Zhang; Hua Chai
Collective operations in application-level fault-tolerant MPI
Fault-tolerance is becoming a critical issue on high-performance platforms. Checkpointing techniques make programs fault-tolerant by saving their state periodically and restoring this state after failure. System-level checkpointing saves the state ... Keywords: MPI, application-level checkpointing, collective communication, fault-tolerance, non-FIFO communication, scientific computing
Greg Bronevetsky; Daniel Marques; Keshav Pingali; Paul Stodghill
Applications of fault detection methods to industrial processes
Components of industrial processes are often affected by un-permitted or un-expected deviations from normal operation behaviour. The fault detection task consists of determination of the fault present in a system and the time of detection. In addition ... Keywords: fault detection and diagnosis, industrial processes, residuals, symptoms
Ioana Fagarasan; S. S. T. Iliescu
Rigorous Development of Dependable Systems Using Fault Tolerance Views
This paper introduces the Mode and Fault Tolerance Views approach to stepwise rigorous development of critical systems. It supports systematic, structured and recursive modelling of system fault tolerance, including error detection, error recovery and ... Keywords: formal methods, Event-B, fault tolerance, modal systems, case study, AOCS
Ilya Lopatkin; Alexei Iliasov; Alexander Romanovsky
Yet Another Fault Injection Technique : by Forward Body Biasing Injection
expensive fault injection tech- niques, like clock or voltage glitches, are well taken into accountYet Another Fault Injection Technique : by Forward Body Biasing Injection K. TOBICH1,2, P. MAURINE1 Injection, Electromag- netic Attacks, RSA, Chinese Remainder Theorem 1 Introduction Fault injection
Statistical estimation of multiple faults in aircraft gas turbine engines
415 Statistical estimation of multiple faults in aircraft gas turbine engines S Sarkar, C Rao of multiple faults in aircraft gas-turbine engines, based on a statistical pattern recognition tool called commercial aircraft engine. Keywords: aircraft propulsion, gas turbine engines, multiple fault estimation
Ray, Asok
Outlier Detection Rules for Fault Detection in Solar Photovoltaic Arrays
fault detection. Furthermore, the proposed models become more reliable as the number of PV measurements analysis specifically for PV installation. Several fault detection models and monitoring systems have been studied for PV systems [8][14]. PV monitoring and fault detection models based on energy yield and power
Lehman, Brad
Investigation of the effect of gel residue on hydraulic fracture conductivity using dynamic fracture conductivity test
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.
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.
Fault reconnaissance agent for sensor networks
One of the key prerequisite for a scalable, effective and efficient sensor network is the utilization of low-cost, low-overhead and high-resilient fault-inference techniques. To this end, we propose an intelligent agent system with a problem solving ... Keywords: Management, expectation maximization algorithm, intelligent agents, wireless sensor networks
Elhadi M. Shakshuki; Xinyu Xing; Tarek R. Sheltami
Optimized Fault Location Final Project Report
excessive currents and voltages last long enough to cause equipment damage. CBs have the purpose to connect describes connectivity of the various components in the power system. In order to process retrieved fault, the system topology must be known. Beside the connectivity it is necessary to obtain information about
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.
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)
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.
The Influence of fold and fracture development on reservoir behavior of the Lisburne Group of northern Alaska
The Carboniferous Lisburne Group is a major carbonate reservoir unit in northern Alaska. The Lisburne is folded and thrust faulted where it is exposed throughout the Brooks Range, but is relatively undeformed in areas of current production in the subsurface of the North Slope. The objectives of this study were to develop a better understanding of four major aspects of the Lisburne: (1) The geometry and kinematics of folds and their truncation by thrust faults. (2) The influence of folding on fracture patterns. (3) The influence of deformation on fluid flow. (4) Lithostratigraphy and its influence on folding, faulting, fracturing, and reservoir characteristics. Symmetrical detachment folds characterize the Lisburne in the northeastern Brooks Range. In contrast, Lisburne in the main axis of the Brooks Range is deformed into imbricate thrust sheets with asymmetrical hangingwall anticlines and footwall synclines. The Continental Divide thrust front separates these different structural styles in the Lisburne and also marks the southern boundary of the northeastern Brooks Range. Field studies were conducted for this project during 1999 to 2001 in various locations in the northeastern Brooks Range and in the vicinity of Porcupine Lake, immediately south of the Continental Divide thrust front. Results are summarized below for the four main subject areas of the study.
Wesley K. Wallace; Catherine L. Hanks; Jerry Jensen: Michael T. Whalen; Paul Atkinson; Joseph Brinton; Thang Bui; Margarete Jadamec; Alexandre Karpov; John Lorenz; Michelle M. McGee; T.M. Parris; Ryan Shackleton
A finite element model for three dimensional hydraulic fracturing
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
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
Coordinated Fault Tolerance for High-Performance Computing
Our work to meet our goal of end-to-end fault tolerance has focused on two areas: (1) improving fault tolerance in various software currently available and widely used throughout the HEC domain and (2) using fault information exchange and coordination to achieve holistic, systemwide fault tolerance and understanding how to design and implement interfaces for integrating fault tolerance features for multiple layers of the software stack�from the application, math libraries, and programming language runtime to other common system software such as jobs schedulers, resource managers, and monitoring tools.
Dongarra, Jack; Bosilca, George; et al.
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...
Hydraulic fractures traced by monitoring microseismic events
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...
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)
Geothermal: Sponsored by OSTI -- Injection through fractures
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
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.
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...
MML Leads Discussion of Dynamic Fracture Testing
Dynamic Fracture in Steel. ... More recently, the pipeline industry has been adopting the CTOA ... fatigue characteristics of new pipeline steels, as these ...
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.
Molecular Dynamics Simulation of Thermoset Fracture with ...
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
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
Mar 14, 2012 ... Investigations on the crack propagation resistance showed an increasing fracture resistance with crack extension, so-called R-curve behavior.
Enhancing in situ bioremediation with pneumatic fracturing
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.
Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks
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
Active Fault Segments As Potential Earthquake Sources- Inferences From
Active Fault Segments As Potential Earthquake Sources- Inferences From Active Fault Segments As Potential Earthquake Sources- Inferences From Integrated Geophysical Mapping Of The Magadi Fault System, Southern Kenya Rift Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Active Fault Segments As Potential Earthquake Sources- Inferences From Integrated Geophysical Mapping Of The Magadi Fault System, Southern Kenya Rift Details Activities (0) Areas (0) Regions (0) Abstract: Southern Kenya Rift has been known as a region of high geodynamic activity expressed by recent volcanism, geothermal activity and high rate of seismicity. The active faults that host these activities have not been investigated to determine their subsurface geometry, faulting intensity and constituents (fluids, sediments) for proper characterization of tectonic
Definition: Enhanced Fault Detection Technology | Open Energy Information
Technology Technology Jump to: navigation, search Dictionary.png Enhanced Fault Detection Technology Enhanced fault detection technology enables higher precision and greater discrimination of fault location and type with coordinated measurement among multiple devices. For distribution applications, this technology can detect and isolate faults without full-power re-closing, reducing the frequency of through-fault currents. Using high resolution sensors and fault signatures, this technology can better detect high impedance faults. For transmission applications, this technology will employ high speed communications between multiple elements (e.g., stations) to protect entire regions, rather than just single elements. It can also use the latest digital techniques to advance beyond conventional impedance relaying of
Upper crustal faulting in an obliquely extending orogen, structural control
faulting in an obliquely extending orogen, structural control faulting in an obliquely extending orogen, structural control on permeability and production in the Coso Geothermal Field, eastern California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Upper crustal faulting in an obliquely extending orogen, structural control on permeability and production in the Coso Geothermal Field, eastern California Details Activities (1) Areas (1) Regions (0) Abstract: New multifold seismic reflection data from the Coso geothermal field in the central Coso Range, eastern California, image brittle faults and other structures in a zone of localized crustal extension between two major strike-slip faults. The Coso Wash fault, a Quaternary-active normal fault that is a locus of surface geothermal activity, is well-imaged as a
New method for abbreviating the fault tree graphical representation
Fault tree analysis is being widely used for reliability and safety analysis of systems encountered in the nuclear industry and elsewhere. A disadvantage of the fault tree method is the voluminous fault tree graphical representation that conventionally results from analysis of a complex system. Previous methods for shortening the fault tree graphical representation include (1) transfers within the fault tree, and (2) the use of the SAMPLE (K out of N logic) gate, the MATRIX gate, and the SUMMATION gate. The purpose of this presentation is to introduce TABULATION gates as a method to abbreviate the fault tree graphical representation. These new gates reduce the cost of analysis and generally increase the system behavior visibility that is inherent in the fault tree technique. (auth)
Stewart, M.E.; Fussell, J.B.; Crump, R.J.
Interpretation of drill cuttings from geothermal wells
Problems in interpreting drill cuttings, as opposed to drill cores, and methods to solve these problems are outlined. The following are covered: identification of lithology; recognition of faults and fractures; interpretation of hydrothermal alteration; geochemistry; sample collection; sample preparple examination; and sample storage. (MHR)
Hulen, J.B.; Sibbett, B.S.
Rock Lab Analysis | Open Energy Information
Rock Lab Analysis Rock Lab Analysis Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Rock Lab Analysis Details Activities (0) Areas (0) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Lab Analysis Techniques Exploration Sub Group: Rock Lab Analysis Parent Exploration Technique: Lab Analysis Techniques Information Provided by Technique Lithology: Core and cuttings analysis is done to define lithology. Water rock interaction. Can determine detailed information about rock composition and morphology. Density of different lithologic units. Rapid and unambiguous identification of unknown minerals.[1] Stratigraphic/Structural: Core analysis can locate faults or fracture networks. Oriented core can give additional important information on anisotropy. Historic structure and deformation of land.
Modeling Hydrogeological and Geomenchanical Processes Related to CO2 Injection in a Faulted Multilayer System
consists of highly fractured shale across the first caprockInitially, the fractured shale zones are considered sealedlayers with caprocks of shale as well as highly fractured
Rutqvist, Jonny; Birkholzer, Jens; Tsang, Chin-Fu
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.
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-
Faults and gravity anomalies over the East Mesa hydrothermal-geothermal system
Detailed interpretations of gravity anomalies over geothermal systems may be extremely useful for mapping the fracture or fault systems that control the circulation of the thermal waters. This approach seems to be particularly applicable in areas like the Salton Trough where reactions between the thermal waters and the porous sediments produce authigenic-hydrothermal minerals in sufficient quantity to cause distinct gravity anomalies at the surface. A 3-D inversion of the residual Bouguer gravity anomaly over the East Mesa geothermal field was made to examine the densified volume of rock. We show that the data not only resolve a north-south and an intersecting northwest structure, but that it may be possible to distinguish between the active present-day hydrothermal system and an older and cooler part of the system. The densified region is compared spatially to self-potential, thermal and seismic results and we find a good concordance between the different geophysical data sets. Our results agree with previous studies that have indicated that the main feeder fault recharging the East Mesa reservoir dips steeply to the west.
Goldstein, N.E.; Carle, S.
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.
Neural net application to transmission line fault detection and classification
Today, in electric power systems, a large amount of data is made readily available at the occurrence of a fault due to the use of advanced communication systems, digital relays and fault recorders. Such systems are intended to obtain data from contacts of the relays and circuit breakers under operation. In addition, corresponding voltages and currents are recorded during prefault, fault and postfault periods. Restoration of power Systems after a fault occurred requires quick judgment. Hence, fault analysis, as the first step of restoration is very important. However, since faults in power systems are various and relaying systems may be complex, fault analysis is difficult to automate. Common practice in power utility companies, today, is to perform fault analysis by expert operators using their knowledge about the power systems and experience with past faults. Because of the time required to deal with complex fault situations, detailed fault analysis can not be performed by human operators in a short time. Therefore, on-line automated fault analysis system is strongly desired. Traditional approaches to the problem of analysis is to construct a heuristic, rule-based system which embodies a portion of the compiled experience of a human expert. These systems perform fault analysis by mapping fault indications to fault hypotheses. 'These hypotheses are used as inputs for next level of rules. After completion of inferencing process, conclusions are given. The knowledge acquisition process is exhaustive and time consuming. Also, data processing is usually too slow to be effectively applied in a real-time environment. Neural computing is one of the rapidly expanding areas of current research. Neural nets have some obvious advantages over expert systems. They are computationally more effective because of their parallel processing capabilities. Also, there is no need for detailed knowledge acquisition part, because neural nets learn by example. This thesis presents results of a study on using the new neural net system that can perform both on-line and off-line fault detection and classification. Fault analysis is conceptualized as a pattern classification problem which involves the association of input patterns representing the power system state to one or more fault conditions.
Rikalo, Igor
Undulator Hall Air Temperature Fault Scenarios
Recent experience indicates that the LCLS undulator segments must not, at any time following tuning, be allowed to change temperature by more than about {+-}2.5 C or the magnetic center will irreversibly shift outside of acceptable tolerances. This vulnerability raises a concern that under fault conditions the ambient temperature in the Undulator Hall might go outside of the safe range and potentially could require removal and retuning of all the segments. In this note we estimate changes that can be expected in the Undulator Hall air temperature for three fault scenarios: (1) System-wide power failure; (2) Heating Ventilation and Air Conditioning (HVAC) system shutdown; and (3) HVAC system temperature regulation fault. We find that for either a system-wide power failure or an HVAC system shutdown (with the technical equipment left on), the short-term temperature changes of the air would be modest due to the ability of the walls and floor to act as a heat ballast. No action would be needed to protect the undulator system in the event of a system-wide power failure. Some action to adjust the heat balance, in the case of the HVAC power failure with the equipment left on, might be desirable but is not required. On the other hand, a temperature regulation failure of the HVAC system can quickly cause large excursions in air temperature and prompt action would be required to avoid damage to the undulator system.
Sevilla, J.
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
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�...
Irradiation Effects on Human Cortical Bone Fracture Behavior
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...
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
An Alternate Approach for Characterizing the Fracture Resistance of ...
While the elastic properties and strength of fish scales have received considerable attention, the resistance to fracture has not. Here the fracture resistance of�...
Hydraulic Fracturing Technology | Department of Energy
Oil & Gas » Shale Gas » Hydraulic Oil & Gas » Shale Gas » Hydraulic Fracturing Technology Hydraulic Fracturing Technology Image taken from "Shale Gas: Applying Technology to Solve America's Energy Challenges," NETL, 2011. Image taken from "Shale Gas: Applying Technology to Solve America's Energy Challenges," NETL, 2011. Hydraulic fracturing is a technique in which large volumes of water and sand, and small volumes of chemical additives are injected into low-permeability subsurface formations to increase oil or natural gas flow. The injection pressure of the pumped fluid creates fractures that enhance gas and fluid flow, and the sand or other coarse material holds the fractures open. Most of the injected fluid flows back to the wellbore and is pumped to the surface.
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.
Calculating the probability of injected carbon dioxide plumes encountering faults
One of the main concerns of storage in saline aquifers is leakage via faults. In the early stages of site selection, site-specific fault coverages are often not available for these aquifers. This necessitates a method using available fault data to estimate the probability of injected carbon dioxide encountering and migrating up a fault. The probability of encounter can be calculated from areal fault density statistics from available data, and carbon dioxide plume dimensions from numerical simulation. Given a number of assumptions, the dimension of the plume perpendicular to a fault times the areal density of faults with offsets greater than some threshold of interest provides probability of the plume encountering such a fault. Application of this result to a previously planned large-scale pilot injection in the southern portion of the San Joaquin Basin yielded a 3% and 7% chance of the plume encountering a fully and half seal offsetting fault, respectively. Subsequently available data indicated a half seal-offsetting fault at a distance from the injection well that implied a 20% probability of encounter for a plume sufficiently large to reach it.
Jordan, P.D.
Coupled thermohydromechanical analysis of a heater test in unsaturated clay and fractured rock at Kamaishi Mine
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
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
The self-potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of -200 mV/MPa. However for pressure drops >2 MPa, the magnitude of the Cc increases by 80% in an exponential trend. This increasing Cc is related to increasing permeability at high pore pressures caused by dilatancy of micro-cracks, and is explained by a decrease in the hydraulic tortuosity. Resistivity measurements reveal a decrease of 2% prior to hydraulic fracturing and a decrease of {approx}35% after fracturing. An asymmetric spatial SP response created by injectate diffusion into dilatant zones is observed prior to hydraulic fracturing, and in most cases this SP variation revealed the impending crack geometry seconds before failure. At rupture, injectate rushes into the new fracture area where the zeta potential is different than in the rock porosity, and an anomalous SP spike is observed. After fracturing, the spatial SP distribution reveals the direction of fracture propagation. Finally, during tensile cracking in a point load device with no water flow, a SP spike is observed that is caused by contact electrification. However, the time constant of this event is much less than that for transients observed during hydraulic fracturing, suggesting that SP created solely from material fracture does not contribute to the SP response during hydraulic fracturing.
Application of Support Vector Machine (SVM) and Proximal Support Vector Machine (PSVM) for fault classification of monoblock centrifugal pump
Monoblock centrifugal pumps are widely used in a variety of applications. Defects and malfunctions (faults) of these pumps result in significant economic loss. Therefore, the pumps must be under constant monitoring. When a possible fault is detected, ... Keywords: CAV, PSVM, bearing faults, cavitation, decision trees, fault classification, fault diagnosis, impeller faults, monoblock centrifugal pumps, proximal SVM, seal faults, support vector machines, vibration signals
N. R. Sakthivel; V. Sugumaran; Binoy B. Nair
that could induce hydraulic fracturing or (2) the criticalpressure for onset of hydraulic fracturing of shear slip,
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
Type E: Extensional Tectonic, Fault-Controlled Resource | Open Energy
Type E: Extensional Tectonic, Fault-Controlled Resource Type E: Extensional Tectonic, Fault-Controlled Resource Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Print PDF Type E: Extensional Tectonic, Fault-Controlled Resource Dictionary.png Type E: Extensional Tectonic, Fault-Controlled Resource: No definition has been provided for this term. Add a Definition Brophy Occurrence Models This classification scheme was developed by Brophy, as reported in Updating the Classification of Geothermal Resources.[1] Type A: Magma-heated, Dry Steam Resource Type B: Andesitic Volcanic Resource Type C: Caldera Resource Type D: Sedimentary-hosted, Volcanic-related Resource Type E: Extensional Tectonic, Fault-Controlled Resource Type F: Oceanic-ridge, Basaltic Resource Extensional-tectonic, fault-controlled resources typically result from a
Fault Mapping At Raft River Geothermal Area (1993) | Open Energy
Fault Mapping At Raft River Geothermal Area (1993) Fault Mapping At Raft River Geothermal Area (1993) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Fault Mapping At Raft River Geothermal Area (1993) Exploration Activity Details Location Raft River Geothermal Area Exploration Technique Fault Mapping Activity Date 1993 Usefulness useful DOE-funding Unknown Exploration Basis Geologic mapping, strain and kinematic analysis Notes The mountains expose a detachment fault that separates a hanging wall of Paleozoic rocks from Proterozoic and Archean rocks of the footwall. Beneath the detachment lies a 100 to 300m-thick top-to-the-east extensional shear zone. Geologic mapping, strain and kinematic analysis, and 40Ar/39Ar thermochronology suggest that the shear zone and detachment fault had an
Active Faulting in the Coso Geothermal Field, Eastern California | Open
Faulting in the Coso Geothermal Field, Eastern California Faulting in the Coso Geothermal Field, Eastern California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Active Faulting in the Coso Geothermal Field, Eastern California Details Activities (1) Areas (1) Regions (0) Abstract: New mapping documents a series of late Quaternary NNE-striking normal faults in the central Coso Range that dip northwest, toward and into the main production area of the Coso geothermal field. The faults exhibit geomorphic features characteristic of Holocene activity, and locally are associated with fumaroles and hydothermal alteration. The active faults sole into or terminate against the brittle-ductile transition zone (BDT) at a depth of about 4 to 5 km. The BDT is arched upward over a volume of crust
Scalable distributed consensus to support MPI fault tolerance.
As system sizes increase, the amount of time in which an application can run without experiencing a failure decreases. Exascale applications will need to address fault tolerance. In order to support algorithm-based fault tolerance, communication libraries will need to provide fault-tolerance features to the application. One important fault-tolerance operation is distributed consensus. This is used, for example, to collectively decide on a set of failed processes. This paper describes a scalable, distributed consensus algorithm that is used to support new MPI fault-tolerance features proposed by the MPI 3 Forum's fault-tolerance working group. The algorithm was implemented and evaluated on a 4,096-core Blue Gene/P. The implementation was able to perform a full-scale distributed consensus in 305 {mu}s and scaled logarithmically.
Buntinas, D. (Mathematics and Computer Science)
Similarity Matching Techniques for Fault Diagnosis in Automotive Infotainment Electronics
Fault diagnosis has become a very important area of research during the last decade due to the advancement of mechanical and electrical systems in industries. The automobile is a crucial field where fault diagnosis is given a special attention. Due to the increasing complexity and newly added features in vehicles, a comprehensive study has to be performed in order to achieve an appropriate diagnosis model. A diagnosis system is capable of identifying the faults of a system by investigating the observable effects (or symptoms). The system categorizes the fault into a diagnosis class and identifies a probable cause based on the supplied fault symptoms. Fault categorization and identification are done using similarity matching techniques. The development of diagnosis classes is done by making use of previous experience, knowledge or information within an application area. The necessary information used may come from several sources of knowledge, such as from system analysis. In this paper similarity matching tec...
Kabir, Mashud
Brittle fracture phenomena: An hypothesis
It is proposed that: volumetric dilation is a fundamental requirement for brittle fracture involving shear; such dilation commonly involves or is expressed as zonal overpressures; the overpressured zones radiate particle motions which are significant to or dominate seismic radiation from blasting; the overpressures are commonly significant to and may dominate the energetics of blastings. Outstanding problems and gaps in our knowledge regarding fragmentation are discussed. It is argued that there is a common missing factor, dilatancy. Supporting evidence is presented from soils and rock mechanics, blasting experimental data and blasting experience. Computer modeling of fragmentation is discussed and the necessity for the inclusion of dilatancy established. Implications are discussed and a test of the hypothesis proposed.
Britton, K.; Walton, O.R.
Incorporating Rigorous Height Determination into Unified Fracture Design
Hydraulic fracturing plays an important role in increasing production rate in tight reservoirs. The performance of the reservoir after fracturing can be observed from the productivity index. This parameter is dependent on the fracture geometry; height, length and width. Unified fracture design (UFD) offers a method to determine the fracture dimensions providing the maximum productivity index for a specific proppant amount. Then, in order to achieve the maximum productivity index, the treatment schedules including the amount of liquid and proppant used for each stage must be determined according to the fracture dimensions obtained from the UFD. The proppant number is necessary for determining the fracture geometry using the UFD. This number is used to find the maximum productivity index for a given proppant amount. Then, the dimensionless fracture conductivity index corresponding to the maximum productivity index can be computed. The penetration ration, the fracture length, and the propped fracture width can be computed from the dimensionless fracture conductivity. However, calculating the proppant number used in UFD requires the fracture height as an input. The most convenient way to estimate fracture height to input to the UFD is to assume that the fracture height is restricted by stress contrast between the pay zone and over and under-lying layers. In other words, the fracture height is assumed to be constant, independent of net pressure and equal to the thickness of the layer which has the least minimum principal stress. However, in reality, the fracture may grow out from the target formation and the height of fracture is dependent on the net pressure during the treatment. Therefore, it is necessary to couple determination of the fracture height with determination of the other fracture parameters. In this research, equilibrium height theory is applied to rigorously determine the height of fracture. Solving the problem iteratively, it is possible to incorporate the rigorous fracture height determination into the unified fracture design.
Pitakbunkate, Termpan
Impact of Wind Power Integration on Fault Current Management
This report presents a study on the impact of wind power integration on the grid fault current level due to various types of faults that might take place inside or outside of wind farms. Wind power is one of the renewable energy sources that has shown tremendous growth in recent years. The increasing integration of wind energy generation and other distributed renewable energy generation could change grid behavior under fault situations and influence system stability. Specifically, integration of addition...
Enhancing and Testing Fast Fault Screening (FFS) Methodology
The aim of this multi-year study is to develop a methodology for fast prediction of the most severe three-phase fault locations for transient stability studies and rank them in order of severity. The methodology is called Fast Fault Screening (FFS).� The key advantage of the FFS is the ability to quickly scan through thousands of potential fault locations from transient stability perspective and identify the most severe locations. In the previous efforts, FFS was developed for angular ...
Optimizing reservoir management through fracture modeling
Fracture flow will become increasingly important to optimal reservoir management as exploration of geothermal reservoirs continues and as injection of spent fluid increases. The Department of Energy conducts research focused on locating and characterizing fractures, modeling the effects of fractures on movement of fluid, solutes, and heat throughout a reservoir, and determining the effects of injection on long-term reservoir production characteristics in order to increase the ability to predict with greater certainty the long-term performance of geothermal reservoirs. Improvements in interpreting and modeling geophysical techniques such as gravity, self potential, and aeromagnetics are yielding new information for the delineation of active major conduits for fluid flow. Vertical seismic profiling and cross-borehole electromagnetic techniques also show promise for delineating fracture zones. DOE funds several efforts for simulating geothermal reservoirs. Lawrence Berkeley Laboratory has adopted a continuum treatment for reservoirs with a fracture component. Idaho National Engineering Laboratory has developed simulation techniques which utilize discrete fractures and interchange of fluid between permeable matrix and fractures. Results of these research projects will be presented to industry through publications and appropriate public meetings. 9 refs.
Renner, J.L.
Timer-based composition of fault-containing self-stabilizing protocols
One of the desired properties of distributed systems is self-adaptability against faults. Self-stabilizing protocols provide autonomous recovery from any finite number of transient faults. However, in practice, catastrophic faults rarely occur, while ... Keywords: Distributed system, Fault tolerance, Fault-containment, Hierarchical composition, Self-adaptability, Self-stabilization, Synchronizer, Timer
Yukiko Yamauchi; Sayaka Kamei; Fukuhito Ooshita; Yoshiaki Katayama; Hirotsugu Kakugawa; Toshimitsu Masuzawa
Historic Surface Faulting and Paleoseismicity in the Area of...
Historic Surface Faulting and Paleoseismicity in the Area of the 1954 Rainbow Mountain-Stillwater Earthquake Sequence, Central Nevada Jump to: navigation, search OpenEI Reference...
Low-cost motor drive embedded fault diagnosis systems
Electric motors are used widely in industrial manufacturing plants. Bearing faults, insulation faults, and rotor faults are the major causes of electric motor failures. Based on the line current analysis, this dissertation mainly deals with the low cost incipient fault detection of inverter-fed driven motors. Basically, low order inverter harmonics contributions to fault diagnosis, a motor drive embedded condition monitoring method, analysis of motor fault signatures in noisy line current, and a few specific applications of proposed methods are studied in detail. First, the effects of inverter harmonics on motor current fault signatures are analyzed in detail. The introduced fault signatures due to harmonics provide additional information about the motor faults and enhance the reliability of fault decisions. It is theoretically and experimentally shown that the extended fault signatures caused by the inverter harmonics are similar and comparable to those generated by the fundamental harmonic on the line current. In the next chapter, the reference frame theory is proposed as a powerful toolbox to find the exact magnitude and phase quantities of specific fault signatures in real time. The faulty motors are experimentally tested both offline, using data acquisition system, and online, employing the TMS320F2812 DSP to prove the effectiveness of the proposed tool. In addition to reference frame theory, another digital signal processor (DSP)-based phasesensitive motor fault signature detection is presented in the following chapter. This method has a powerful line current noise suppression capability while detecting the fault signatures. It is experimentally shown that the proposed method can determine the normalized magnitude and phase information of the fault signatures even in the presence of significant noise. Finally, a signal processing based fault diagnosis scheme for on-board diagnosis of rotor asymmetry at start-up and idle mode is presented. It is quite challenging to obtain these regular test conditions for long enough time during daily vehicle operations. In addition, automobile vibrations cause a non-uniform air-gap motor operation which directly affects the inductances of electric motor and results quite noisy current spectrum. The proposed method overcomes the challenges like aforementioned ones simply by testing the rotor asymmetry at zero speed.
Akin, Bilal
Intersecting Fault Trends and Crustal-Scale Fluid Pathways Below...
Intersecting Fault Trends and Crustal-Scale Fluid Pathways Below the Dixie Valley Geothermal Area, Nevada, Inferred from 3d Magnetotelluric Surveying Jump to: navigation, search...
Thermal Waters Along The Konocti Bay Fault Zone, Lake County...
Thermal Waters Along The Konocti Bay Fault Zone, Lake County, California- A Re-Evaluation Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Thermal...
Fault Detection and Diagnosis in Building HVAC Systems
diagnostic method for vapor compression air conditioners�,evaluation of faults in vapor compression cycle equipment�,Diagnostic Methods to Vapor Compression Cooling Equipment�,
Upper crustal faulting in an obliquely extending orogen, structural...
faulting in an obliquely extending orogen, structural control on permeability and production in the Coso Geothermal Field, eastern California Jump to: navigation, search...
Dynamic analysis and fault diagnosis of a water hydraulic motor.
??This research is concerned with condition monitoring and fault diagnosis of the piston of the water hydraulic motor by vibration signal analysis. Vibration signatures are� (more)
Chen, Hanxin.
MICRO-SEISMICITY, FAULT STRUCTURE AND HYDRAULIC COMPARTMENTALIZATION WITHIN THE COSO GETHERMAL FIELD, CALIFORNIA Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home...
CiFTS : Coordinated Infrastructure for Fault Tolerant Systems
Demos Team News Contact Us Coordinated and Improved Fault Tolerance for High Performance Computing Systems In the next few years SciDAC applications will utilize exascale...
Petri net modeling of fault analysis for probabilistic risk assessment.
??Fault trees and event trees have been widely accepted as the modeling strategy to perform Probabilistic Risk Assessment (PRA). However, there are several limitations associated� (more)
Lee, Andrew
An Assessment of Fault Current Limiter Testing Requirements ...
Energy Reliability (OE) is conducting research and development (R&D) on next-generation electricity delivery equipment including fault current limiters (FCLs). Prototype FCL...
Cryptic Faulting and Multi-Scale Geothermal Fluid Connections...
Cryptic Faulting and Multi-Scale Geothermal Fluid Connections in the Dixie Valley-Central Nevada Seismic Belt Area- Implications from Mt Resistivity Surveying Jump to: navigation,...
Recency Of Faulting And Neotechtonic Framework In The Dixie Valley...
Recency Of Faulting And Neotechtonic Framework In The Dixie Valley Geothermal Field And Other Geothermal Fields Of The Basin And Range Jump to: navigation, search GEOTHERMAL...
Recent earthquake sequences at Coso: Evidence for conjugate faulting...
Recent earthquake sequences at Coso: Evidence for conjugate faulting and stress loading near a geothermal field Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal...
Potential Contaminant Pathways from Hydraulically Fractured Shale to Aquifers
Potential Contaminant Pathways from Hydraulically Fractured Shale to Aquifers by Tom Myers Abstract Hydraulic fracturing of deep shale beds to develop natural gas has caused concern regarding the potential and preferential flow through fractures--could allow the transport of contaminants from the fractured shale
Fault Prediction and Fault-Tolerant of Lithium-ion Batteries Temperature Failure for Electric Vehicle
Design and implementation of dual-redundancy was developed to predict Lithium-ion battery failure for electric vehicle. Data fusion unit, prediction unit and determination unit were designed. Outputs from original and redundant sensors were integrated ... Keywords: Lithium-ion battery, dual-redundancy, data fusion, prediction, Fault-tolerant
Hu Chunhua; He Ren; Wang Runcai; Yu Jianbo
A fuzzy neural network based fault detection scheme for synchronous generator with internal fault
A fuzzy neural network (FNN) based inter-turn short circuit fault detection scheme for generator is proposed. The second harmonic magnitude of field current and the negative sequence components of voltages and currents are used as inputs for the FNN ...
Hongwei Fang; Changliang Xia
Prototyping a fault-tolerant multiprocessor SoC with run-time fault recovery
Modern integrated circuits (ICs) are becoming increasingly complex. The complexity makes it difficult to design, manufacture and integrate these high performance ICs. The advent of multiprocessor Systems-on-chips (SoCs) makes it even more challenging ... Keywords: fault-tolerance, multiprocessor system, network-on-chip, retargetable simulation, run-time verification, system-on-chip
Xinping Zhu; Wei Qin
Does hydraulic-fracturing theory work in jointed rock masses
The hypocenter locations of micro-earthquakes (acoustic emissions) generated during fracturing typically are distributed three-dimensionally suggesting that fracturing stimulates a volumetric region, rather than the planar fracture theoretically expected. The hypocenter maps generated at six operating, or potential, HDR reservoirs in the US, Europe and Japan are examined in detail and the fracture dimensions are correlated with fracture injection volumes and formation permeability. Depsite the volumetric appearance of the maps we infer that the induced fractures are mainly planar and may propagate aseismically. The induced seismicity stems from nearby joints, which are not opened significantly by fracturing, but are caused to shear-slip because of local pore pressure.
Murphy, H.D.; Keppler, H.; Dash, Z.V.
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.
Physical model of a fractured reservoir | Open Energy Information
model of a fractured reservoir model of a fractured reservoir Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Physical model of a fractured reservoir Details Activities (1) Areas (1) Regions (0) Abstract: The objectives of the physical modeling effort are to: (1) evaluate injection-backflow testing for fractured reservoirs under conditions of known reservoir parameters (porosity, fracture width, etc.); (2) study the mechanisms controlling solute transport in fracture systems; and (3) provide data for validation of numerical models that explicitly simulate solute migration in fracture systems. The fracture network is 0.57-m wide, 1.7-m long, and consists of two sets of fractures at right angles to one another with a fracture spacing of 10.2 cm. A series of
Method of optimizing the conductivity of a propped fractured formation
This patent describes a method of reducing viscosity of a fracturing fluid containing proppant, a polymer, a delayed breaker and a nondelayed breaker, it comprises: introducing the fracturing fluid into a subterranean formation to form at least one fracture; depositing the proppant and the polymer in the fracture; determining an after closure polymer viscosity of the deposited polymer in the fracture; selecting a proppant pack permeability in the fracture; calculating an amount of breaker necessary to reduce the after closure viscosity of the deposited polymer to attain the selected permeability of; determining a minimum viscosity of the fracturing fluid which maintains the proppant in suspension in the fluid during pumping in the fracture; and introducing an effective amount of delayed breaker and nondelayed breaker into the fracturing fluid to attain the selected proppant pack permeability while maintaining the minimum viscosity to maintain the proppant in suspension in the fluid during pumping in the fracture.
Brannon, H.D.; Gulbis, J.; King, M.T.; Hawkins, G.W.
Domain Decomposition for Flow in Porous Media with Fractures
this article. The fractures that we are concerned with are filled with debris so we consider them as porous media. The permeability in the fracture is large in comparison with that in the surrounding rock, so the fluid circulates faster in the fracture. Thus we have a highly heterogeneous porous medium. One idea that has been used to take this into account is to treat the fracture as an interface and to assume that the fluid that flows into the fracture stays in the fracture. In fact, in many models the contrast in permeabilities is of such an order that the flow outside of the fracture is neglected. However, here we are concerned with the situation in which the exchange between the fracture and the rest of the domain is significant. To deal with this case we need to model both what happens in the fracture and what happens outside the fracture. One
Clarisse Alboin; Jerome Jaffre; Jean Roberts; Christophe Serres
A Study of Latrogenic Fracture Risk in Reduction of Pipkin Fracture ...
This study evaluated the risk of such fractures during closed reduction of Pipkin ... of Ti-6Al-4V for Medical Applications after Surface Modification by Anodization.
Geomechanical review of hydraulic fracturing technology
Hydraulic fracturing as a method for recovering unconventional shale gas has been around for several decades. Significant research and improvement in field methods have been documented in literature on the subject. The ...
Arop, Julius Bankong
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.
Definition: Hydraulic Fracturing | Open Energy Information
Jump to: navigation, search Dictionary.png Hydraulic Fracturing The process used in the Oil and Gas industry of drilling deep into the ground and injecting water, sand, and other...
Multiphase flow in fractured porous media
The major goal of this research project was to improve the understanding of the gas-oil two-phase flow in fractured porous media. In addition, miscible displacement was studied to evaluate its promise for enhanced recovery.
Firoozabadi, A.
On Water Flow in Hot Fractured Rock -- A Sensitivity Study on the Impact of Fracture-Matrix Heat Transfer
of multiphase, multicomponent fluid mixtures in porous andmultiphase heat and mass flow in unsaturated fractured porous
Birkholzer, Jens T.; Zhang, Yingqi
Automating Power System Fault Diagnosis through Multi-Agent System Technology
Fault diagnosis within electrical power systems is a time consuming and complex task. SCADA systems, digital fault recorders, travelling wave fault locators and other monitoring devices are drawn upon to inform the engineers of incidents, problems and ...
S. D. J. McArthur; E. M. Davidson; J. A. Hossack; J. R. McDonald
Feng shui of supercomputer memory: positional effects in DRAM and SRAM faults
Several recent publications confirm that faults are common in high-performance computing systems. Therefore, further attention to the faults experienced by such computing systems is warranted. In this paper, we present a study of DRAM and SRAM faults ...
Vilas Sridharan, Jon Stearley, Nathan DeBardeleben, Sean Blanchard, Sudhanva Gurumurthi
Hydraulic fracturing and propping tests at Yakedake field in Japan
Hydraulic fracturing experiments have been conducted at Yakedake field in Gifu prefecture, Japan. From the data obtained during the fracturing operation, the open-hole section permeability was estimated of the wellbore, the minimum pressure required to propagate the fracture, the impedances before and after the propping, and the earth stress normal to the fracture plane. The final fracture plane was also mapped with the microseismic events.
Yamaguchi, Tsutomu; Seo, Kunio; Suga, Shoto; Itoh, Toshinobu; Kuriyagawa, Michio
NFFLOW: A reservoir simulator incorporating explicit fractures (SPE 153890)
NFFLOW is a research code that quickly and inexpensively simulates flow in moderately fractured reservoirs. It explicitly recognizes fractures separately from rock matrix. In NFFLOW fracture flow is proportional to the pressure gradient along the fracture, and flow in the rock matrix is determined by Darcy�s Law. The two flow mechanisms are coupled through the pressure gradient between a fracture and its adjacent rock matrix. Presented is a promising change to NFFLOW that allows for flow across a rock matrix block.
Boyle, E.J.; Sams, W.N.
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.
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.
First step towards automatic correction of firewall policy faults
Firewalls are critical components of network security and have been widely deployed for protecting private networks. A firewall determines whether to accept or discard a packet that passes through it based on its policy. However, most real-life firewalls ... Keywords: Automatic fault fixing, firewall faults, firewall policy
Fei Chen; Alex X. Liu; Jeehyun Hwang; Tao Xie
Fault Diagnosis of Transformer Based on Random Forest
Fault diagnosis of transformer in power system is studied in this paper. Considering the excellent performances of Random Forest (RF) in pattern recognition, we apply RF to construct a diagnosis model to predict the situation of transformer. The experiments ... Keywords: Rondom Forest, fault diagnosis of transformer, classification model
Xi Chen; Hongmei Cui; Linkai Luo
Towards Robustness in Neural Network Based Fault Diagnosis
Challenging design problems arise regularly in modern fault diagnosis systems. Unfortunately, classical analytical techniques often cannot provide acceptable solutions to such difficult tasks. This explains why soft computing techniques such as neural ... Keywords: Dynamic Neural Network, Fault Diagnosis, Gmdh Neural Network, Robustness
Krzysztof Patan; Marcin Witczak; J�Zef Korbicz
Fault detection in multivariate signals with applications to gas turbines
This paper proposes a fault detection method for multivariate signals. The method assesses whether or not the multivariate autocovariance functions of two independently sampled system signals coincide. If the first signal is known to be sampled from ... Keywords: autocovariances, fault detection, spectral analysis, stationary time series
Hany Bassily; Robert Lund; John Wagner
Symbolic identification for fault detection in aircraft gas turbine engines
Symbolic identification for fault detection in aircraft gas turbine engines S Chakraborty, S Sarkar and computationally inexpensive technique of component-level fault detection in aircraft gas-turbine engines identification, gas turbine engines, language-theoretic analysis 1 INTRODUCTION The propulsion system of modern
CUDA accelerated fault tree analysis with C-XSC
Fault tree analysis is a widespread mathematical method for determining the failure probability of observed real-life systems. In addition to failure probability defined by wear, the system model has to take into account intrinsic and extrinsic system ... Keywords: C-XSC, CUDA, DSI, fault tree analysis
Gabor Rebner; Michael Beer
GPS satellite oscillator faults mimicking ionospheric phase scintillation
It is possible for unreported Global Positioning System satellite faults to cause phase variations mimicking the effect of ionospheric scintillation. A case study of an event on 17 May, 2011 is presented. For approximately 695 s, the L1 signal from the ... Keywords: Anomaly, Fault, Navstar 43, PRN 13, Scintillation, Sigma-phi
Christopher J. Benton; Cathryn N. Mitchell
Plants and Power Systems Control, Kananaskis, Canada, 2006 #12;Area Measurement System (WAMS) and Phasor variables. Methods based on traveling waves and recently based on fault- generated high-frequency transients of the fault location. This method will be more attractive when the concept of Wide IFAC Symposium on Power
Online Fault Detection and Tolerance for Photovoltaic Energy Harvesting Systems
Online Fault Detection and Tolerance for Photovoltaic Energy Harvesting Systems Xue Lin 1 , Yanzhi, yanzhiwa, dizhu, firstname.lastname@example.com, 2 firstname.lastname@example.com ABSTRACT Photovoltaic energy harvesting systems (PV systems) are subject to PV cell faults, which decrease the efficiency of PV systems and even
Pedram, Massoud
Soft computing approach to fault diagnosis of centrifugal pump
Fault detection and isolation in rotating machinery is very important from an industrial viewpoint as it can help in maintenance activities and significantly reduce the down-time of the machine, resulting in major cost savings. Traditional methods have ... Keywords: Centrifugal pump, Decision tree algorithm, Fault diagnosis, Gene expression programming, Proximal support vector machine, Statistical features, Support vector machine
N. R. Sakthivel; Binoy.B.Nair; V. Sugumaran
ANFIS based sensor fault detection for continuous stirred tank reactor
In this paper, an Adaptive Neuro-Fuzzy Inference System (ANFIS) based Sensor fault detection and isolation for Continuous Stirred Tank Reactor (CSTR) is proposed. CSTR is a highly nonlinear process exhibiting stable and unstable steady state at different ... Keywords: ANFIS observer, Continuous stirred tank reactor, Dedicated observer, Fault detection
U. Sabura Banu; G. Uma
Increasing fault-tolerance in cellular automata-based systems
In the light of emergence of cellular computing, new cellular computing systems based on yet-unknown methods of fabrication need to address the problem of fault tolerance in a way which is not tightly connected to used technology. This may not be possible ... Keywords: Byl's loop, Game of Life, TMR, cellular automata, cellular computing, fault tolerance, rule 30, static module redundance
Lud?k �aloudek; Luk� Sekanina
Automatic Fault Characterization via Abnormality-Enhanced Classification
Enterprise and high-performance computing systems are growing extremely large and complex, employing hundreds to hundreds of thousands of processors and software/hardware stacks built by many people across many organizations. As the growing scale of these machines increases the frequency of faults, system complexity makes these faults difficult to detect and to diagnose. Current system management techniques, which focus primarily on efficient data access and query mechanisms, require system administrators to examine the behavior of various system services manually. Growing system complexity is making this manual process unmanageable: administrators require more effective management tools that can detect faults and help to identify their root causes. System administrators need timely notification when a fault is manifested that includes the type of fault, the time period in which it occurred and the processor on which it originated. Statistical modeling approaches can accurately characterize system behavior. However, the complex effects of system faults make these tools difficult to apply effectively. This paper investigates the application of classification and clustering algorithms to fault detection and characterization. We show experimentally that naively applying these methods achieves poor accuracy. Further, we design novel techniques that combine classification algorithms with information on the abnormality of application behavior to improve detection and characterization accuracy. Our experiments demonstrate that these techniques can detect and characterize faults with 65% accuracy, compared to just 5% accuracy for naive approaches.
Bronevetsky, G; Laguna, I; de Supinski, B R
Research on Fault Location of Power Cable with Wavelet Analysis
This article researChes for 10kV transmission cable form the ground substation to the underground central substation in the coal mine. The transient traveLing wave signal of the cable fault is disposed by the wavelet transformation based on the cable ... Keywords: Wavelet analysis, Fault Location, TraveLing wave
Ji-meng Zhang; Shuo Liang
Effects of unbalanced faults on transient stability of cogeneration system
This paper evaluates the effects of unbalanced faults on the transient stability of a real cogeneration plant. First, a brief is given for the structure of the cogeneration system. Use of the electromagnetic transient program (EMTP) constructs the cogeneration ... Keywords: CCT curve, EMTP, cogeneration plant, transient stability, unbalanced faults
Wei-Neng Chang; Chia-Han Hsu
Probability Estimation of CO2 Leakage Through Faults at Geologic Carbon Sequestration Sites
for Geologic Carbon Sequestration Based on EffectiveFaults at Geologic Carbon Sequestration Sites Yingqi Zhang*,faults at geologic carbon sequestration (GCS) sites is a
Zhang, Yingqi
Fault Analysis at a Wind Power Plant for One Year of Observation: Preprint
This paper analyzes the fault characteristics observed at a wind power plant, and the behavior of the wind power plant under fault events.
Muljadi, E.; Mills, Z.; Foster, R.; Conto, J.; Ellis, A.
Dating of major normal fault systems using thermochronology- An example
Dating of major normal fault systems using thermochronology- An example Dating of major normal fault systems using thermochronology- An example from the Raft River detachment, Basin and Range, western United States Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Dating of major normal fault systems using thermochronology- An example from the Raft River detachment, Basin and Range, western United States Details Activities (1) Areas (1) Regions (0) Abstract: Application of thermochronological techniques to major normal fault systems can resolve the timing of initiation and duration of extension, rates of motion on detachment faults, timing of ductile mylonite formation and passage of rocks through the crystal-plastic to brittle transition, and multiple events of extensional unroofing. Here we determine
Recent earthquake sequences at Coso: Evidence for conjugate faulting and
earthquake sequences at Coso: Evidence for conjugate faulting and earthquake sequences at Coso: Evidence for conjugate faulting and stress loading near a geothermal field Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Recent earthquake sequences at Coso: Evidence for conjugate faulting and stress loading near a geothermal field Details Activities (1) Areas (1) Regions (0) Abstract: Two recent earthquake sequences near the Coso geothermal field show clear evidence of faulting along conjugate planes. We present results from analyzing an earthquake sequence occurring in 1998 and compare it with a similar sequence that occurred in 1996. The two sequences followed mainshocks that occurred on 27 November 1996 and 6 March 1998. Both mainshocks ruptured approximately colocated regions of the same fault
Definition: Apex or Salient of Normal Fault | Open Energy Information
Definition Definition Edit with form History Facebook icon Twitter icon » Definition: Apex or Salient of Normal Fault Jump to: navigation, search Dictionary.png Apex or Salient of Normal Fault Normal faults may intersect in the subsurface to form a fault apex or salient. Apices or salients of normal faults account for 3% of structural controls in the Great Basin.[2] View on Wikipedia Wikipedia Definition References ↑ James E. Faulds,Nicholas H. Hinz,Mark F. Coolbaugh,Patricia H. Cashman,Christopher Kratt,Gregory Dering,Joel Edwards,Brett Mayhew,Holly McLachlan. 2011. Assessment of Favorable Structural Settings of Geothermal Systems in the Great Basin, Western USA. In: Transactions. GRC Anual Meeting; 2011/10/23; San Diego, CA. Davis, CA: Geothermal Resources Council; p. 777-783
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
Shallow hydraulic fracturing measurements in Korea support tectonic and seismic indicators of regional stress.
We have conducted five hydraulic fracturing stress measurement campaigns in Korea, involving 13 test holes ranging in depth from 30 to 250 m, at locations from North Seoul to the southern coast of the peninsula. The measurements reveal consistent crustal stress magnitudes and directions that suggest persistence throughout western and southern Korea. The maximum horizontal stress {sigma}{sub H} is oriented between ENE-WSW and E-W, in accord with plate movement and deformation, and with directions indicated by both focal mechanism solutions from earthquakes inland and offshore as well as borehole breakouts in mainland China close to its eastern coast. With respect to magnitudes, the vertical stress is the overall minimum stress at all tested locations, suggesting a thrust faulting regime within the relatively shallow depths reached by our tests. Typically, such a stress regime becomes one favoring strike-slip at greater depths, as is also indicated by the focal mechanism solutions around Korea.
Haimson, Bezalel Cecil (University of Wisconsin, Madison, WI); Lee, Moo Yul; Song, I. (Ruhr-University Bochum, Bochum, Germany)
Feb. 11, 2008 Advanced Fault Tolerance Solutions for High Performance Computing 1/47 Advanced Fault Tolerance Solutions
Feb. 11, 2008 Advanced Fault Tolerance Solutions for High Performance Computing 1/47 RAS RAS Advanced Fault Tolerance Solutions for High Performance Computing Christian Engelmann Oak Ridge National Solutions for High Performance Computing 2/47 · Nation's largest energy laboratory · Nation's largest
Engelmann, Christian
Transport of Bottom Water in the Romanche Fracture Zone and the Chain Fracture Zone
Two moored arrays deployed in the Romanche Fracture Zone and Chain Fracture Zone in the equatorial Atlantic Ocean provide two-year-long time series of current and temperature in the Lower North Atlantic Deep Water and the Antarctic Bottom Water. ...
Herl� Mercier; Kevin G. Speer
u l y 2 , 1 9 8 1 HYDRAULIC FRACTURING AND OVERCORING STRESSI nun LBL-12478 HYDRAULIC FRACTURING AND OVERCORING STRESSthe calculated stress. n HYDRAULIC FRACTURING EQUIPMENT AND
Doe, T.
Pressure analysis of the hydromechanical fracture behaviour in stimulated tight sedimentary geothermal reservoirs
Zimmermann, G. , 2005. Hydraulic fracturing in a sedimentaryare described in the hydraulic fracturing context, in whichoverview. However, hydraulic fracturing theories and related
Wessling, S.
Carlsson, H. , "Hydraulic fracturing and overcoring stress1949). Haimson, B.C. , "Hydraulic fracturing in porous andc.B. , "Laboratory hydraulic fracturing experiments in
Ratigan, J.L.
Introducing a Clinical Practice Guideline Using Early CT in the Diagnosis of Scaphoid and Other Fractures
61-6. 30. Kusano N. Diagnosis of Occult Scaphoid Fracture: AMJ, Schaefer-Prokop C, et al. Occult scaphoid fractures:revealing radiographically occult scaphoid fractures. [see
A triple-continuum approach for modeling flow and transport processes in fractured rock
Multiphase Tracer Transport in Heterogeneous Fractured Porousmultiphase, nonisothermal flow and solute transport in fractured porousmultiphase fluid flow, heat transfer, and chemical migration in a fractured porous
Wu, Yu-Shu; Liu, H.H.; Bodvarsson, G.S; Zellmer, K .E.
Recency of Faulting and Neotectonic Framework in the Dixie Valley...
enough to produce significant increases in fracture dilatancy, thereby increasing hydraulic conductivity.We conclude that an understanding of the spatial distribution of active...
A PKN Hydraulic Fracture Model Study and Formation Permeability Determination
Hydraulic fracturing is an important method used to enhance the recovery of oil and gas from reservoirs, especially for low permeability formations. The distribution of pressure in fractures and fracture geometry are needed to design conventional and unconventional hydraulic fracturing operations, fracturing during water-flooding of petroleum reservoirs, shale gas, and injection/extraction operation in a geothermal reservoir. Designing a hydraulic fracturing job requires an understanding of fracture growth as a function of treatment parameters. There are various models used to approximately define the development of fracture geometry, which can be broadly classified into 2D and 3D categories. 2D models include, the Perkins-Kern-Nordgren (PKN) fracture model, and the Khristianovic-Geertsma-de. Klerk (KGD) fracture model, and the radial model. 3D models include fully 3D models and pseudo-three-dimensional (P-3D) models. The P-3D model is used in the oil industry due to its simplification of height growth at the wellbore and along the fracture length in multi-layered formations. In this research, the Perkins-Kern-Nordgren (PKN) fracture model is adopted to simulate hydraulic fracture propagation and recession, and the pressure changing history. Two different approaches to fluid leak-off are considered, which are the classical Carter's leak-off theory with a constant leak-off coefficient, and Pressure-dependent leak-off theory. Existence of poroelastic effect in the reservoir is also considered. By examining the impact of leak-off models and poroelastic effects on fracture geometry, the influence of fracturing fluid and rock properties, and the leak-off rate on the fracture geometry and fracturing pressure are described. A short and wide fracture will be created when we use the high viscosity fracturing fluid or the formation has low shear modulus. While, the fracture length, width, fracturing pressure, and the fracture closure time increase as the fluid leak-off coefficient is decreased. In addition, an algorithm is developed for the post-fracture pressure-transient analysis to calculate formation permeability. The impulse fracture pressure transient model is applied to calculate the formation permeability both for the radial flow and linear fracture flow assumption. Results show a good agreement between this study and published work.
Xiang, Jing
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.
Steps toward fault-tolerant quantum chemistry.
Developing quantum chemistry programs on the coming generation of exascale computers will be a difficult task. The programs will need to be fault-tolerant and minimize the use of global operations. This work explores the use a task-based model that uses a data-centric approach to allocate work to different processes as it applies to quantum chemistry. After introducing the key problems that appear when trying to parallelize a complicated quantum chemistry method such as coupled-cluster theory, we discuss the implications of that model as it pertains to the computational kernel of a coupled-cluster program - matrix multiplication. Also, we discuss the extensions that would required to build a full coupled-cluster program using the task-based model. Current programming models for high-performance computing are fault-intolerant and use global operations. Those properties are unsustainable as computers scale to millions of CPUs; instead one must recognize that these systems will be hierarchical in structure, prone to constant faults, and global operations will be infeasible. The FAST-OS HARE project is introducing a scale-free computing model to address these issues. This model is hierarchical and fault-tolerant by design, allows for the clean overlap of computation and communication, reducing the network load, does not require checkpointing, and avoids the complexity of many HPC runtimes. Development of an algorithm within this model requires a change in focus from imperative programming to a data-centric approach. Quantum chemistry (QC) algorithms, in particular electronic structure methods, are an ideal test bed for this computing model. These methods describe the distribution of electrons in a molecule, which determine the properties of the molecule. The computational cost of these methods is high, scaling quartically or higher in the size of the molecule, which is why QC applications are major users of HPC resources. The complexity of these algorithms means that MPI alone is insufficient to achieve parallel scaling; QC developers have been forced to use alternative approaches to achieve scalability and would be receptive to radical shifts in the programming paradigm. Initial work in adapting the simplest QC method, Hartree-Fock, to this the new programming model indicates that the approach is beneficial for QC applications. However, the advantages to being able to scale to exascale computers are greatest for the computationally most expensive algorithms; within QC these are the high-accuracy coupled-cluster (CC) methods. Parallel coupledcluster programs are available, however they are based on the conventional MPI paradigm. Much of the effort is spent handling the complicated data dependencies between the various processors, especially as the size of the problem becomes large. The current paradigm will not survive the move to exascale computers. Here we discuss the initial steps toward designing and implementing a CC method within this model. First, we introduce the general concepts behind a CC method, focusing on the aspects that make these methods difficult to parallelize with conventional techniques. Then we outline what is the computational core of the CC method - a matrix multiply - within the task-based approach that the FAST-OS project is designed to take advantage of. Finally we outline the general setup to implement the simplest CC method in this model, linearized CC doubles (LinCC).
Taube, Andrew Garvin
Wavelet analysis for gas turbine fault diagnostics
The application of wavelet analysis to diagnosing faults in gas turbines is examined in the present paper. Applying the wavelet transform to time signals obtained from sensors placed on an engine gives information in correspondence to their Fourier transform. Diagnostic techniques based on Fourier analysis of signals can therefore be transposed to the wavelet analysis. In the paper the basic properties of wavelets, in relation to the nature of turbomachinery signals, are discussed. The possibilities for extracting diagnostic information by means of wavelets are examined, by studying the applicability to existing data from vibration, unsteady pressure, and acoustic measurements. Advantages offered, with respect to existing methods based on harmonic analysis, are discussed as well as particular requirements related to practical application.
Aretakis, N.; Mathioudakis, K. [National Technical Univ. of Athens (Greece). Lab. of Thermal Turbomachines
Self field triggered superconducting fault current limiter
A superconducting fault current limiter array with a plurality of superconductor elements arranged in a meanding array having an even number of supconductors parallel to each other and arranged in a plane that is parallel to an odd number of the plurality of superconductors, where the odd number of supconductors are parallel to each other and arranged in a plane that is parallel to the even number of the plurality of superconductors, when viewed from a top view. The even number of superconductors are coupled at the upper end to the upper end of the odd number of superconductors. A plurality of lower shunt coils each coupled to the lower end of each of the even number of superconductors and a plurality of upper shunt coils each coupled to the upper end of each of the odd number of superconductors so as to generate a generally orthoganal uniform magnetic field during quenching using only the magenetic field generated by the superconductors.
Tekletsadik, Kasegn D. (Rexford, NY)
Fault tolerant hypercube computer system architecture
This patent describes a fault-tolerant multi-processor computer system of the hypercube type. It comprises: a plurality of first computing nodes; a first network of message conducting path means for interconnecting the first computing nodes as a hypercube. The first network providing a path for message transfer between the first computing nodes; a first watch dog node; and, a second network of message conducting path means for directly connecting each of the first computing nodes to the first watch dog node independent from the first network. The second network providing an independent path for test message and reconfiguration affecting transfers between respective ones of the first computing nodes and the first watch dog node.
Madan, H.S.; Chow, E.
For some time the public has asked questions about seismic activity related to hydraulic fracturing and other oil-field related activities. In particular, there is concern that the energy that goes into the subsurface during hydraulic fracturing is sufficient to cause felt earthquakes. The following is a response to those questions. 1) Seismic activity that is related to human activities is generally referred to as �induced seismicity � or �triggered seismicity. � Induced seismicity is defined as �seismic events attributable to human activities � (National Research Council, 2012). The term �triggered seismicity � is also used to describe situations in which human activities �could potentially �trigger � large and potentially damaging earthquakes � (Shemeta et al., 2012). The following discussion uses only the term �induced seismicity � to refer to seismic activity in which human activity plays a role. 2) Because it uses energy to fracture rocks to release oil or natural gas, hydraulic fracturing does create microseismic events (of a magnitude less than 2.0). Felt earthquake activity (generally greater than a magnitude 3.0) resulting from hydraulic fracturing has been confirmed from only one location in the world (National Research Council, 2012). In the
unknown authors
The Carboniferous Lisburne Group is a major carbonate reservoir unit in northern Alaska. The Lisburne is detachment folded where it is exposed throughout the northeastern Brooks Range, but is relatively undeformed in areas of current production in the subsurface of the North Slope. The objectives of this study are to develop a better understanding of four major aspects of the Lisburne: (1) The geometry and kinematics of detachment folds and their truncation by thrust faults. (2) The influence of folding on fracture patterns. (3) The influence of deformation on fluid flow. (4) Lithostratigraphy and its influence on folding, faulting, fracturing, and reservoir characteristics. The Lisburne in the main axis of the Brooks Range is characteristically deformed into imbricate thrust sheets with asymmetrical hanging wall anticlines and footwall synclines. In contrast, the Lisburne in the northeastern Brooks Range is characterized by symmetrical detachment folds. The focus of our 2000 field studies was at the boundary between these structural styles in the vicinity of Porcupine Lake, in the Arctic National Wildlife Refuge. The northern edge of thrust-truncated folds in Lisburne is marked by a local range front that likely represents an eastward continuation of the central Brooks Range front. This is bounded to the north by a gently dipping panel of Lisburne with local asymmetrical folds. The leading edge of the flat panel is thrust over Permian to Cretaceous rocks in a synclinal depression. These younger rocks overlie symmetrically detachment-folded Lisburne, as is extensively exposed to the north. Six partial sections were measured in the Lisburne of the flat panel and local range front. The Lisburne here is about 700 m thick and is interpreted to consist primarily of the Wachsmuth and Alapah Limestones, with only a thin veneer of Wahoo Limestone. The Wachsmuth (200 m) is gradational between the underlying Missippian Kayak Shale and the overlying Mississippian Alapah, and increases in resistance upward. The Alapah consists of a lower resistant member (100 m) of alternating limestone and chert, a middle recessive member (100 m), and an upper resistant member (260 m) that is similar to Wahoo in the northeastern Brooks Range. The Wahoo is recessive and is thin (30 m) due either to non-deposition or erosion beneath the sub-Permian unconformity. The Lisburne of the area records two major episodes of transgression and shallowing-upward on a carbonate ramp. Thicknesses and facies vary along depositional strike. Asymmetrical folds, mostly truncated by thrust faults, were studied in and south of the local range front. Fold geometry was documented by surveys of four thrust-truncated folds and two folds not visibly cut by thrusts. A portion of the local range front was mapped to document changes in fold geometry along strike in three dimensions. The folds typically display a long, non-folded gently to moderately dipping backlimbs and steep to overturned forelimbs, commonly including parasitic anticline-syncline pairs. Thrusts commonly cut through the anticlinal forelimb or the forward synclinal hinge. These folds probably originated as detachment folds based on their mechanical stratigraphy and the transition to detachment folds to the north. Their geometry indicates that they were asymmetrical prior to thrust truncation. This asymmetry may have favored accommodation of increasing shortening by thrust breakthrough rather than continued folding. Fracture patterns were documented in the gently dipping panel of Lisburne and the asymmetrical folds within it. Four sets of steeply dipping extension fractures were identified, with strikes to the (1) N, (2) E, (3) N to NW, and (4) NE. The relative timing of these fracture sets is complex and unclear. En echelon sets of fractures are common, and display normal or strike-slip sense. Mesoscopic and penetrative structures are locally well developed, and indicate bed-parallel shear within the flat panel and strain within folds. Three sets of normal faults are well developed in the area, and are unusual
Wesley K. Wallace; Catherine L. Hanks; Jerry Jensen; Michael T. Whalen
Logs and paleoseismic interpretations from trenches 14C and 14D on the Bow Ridge fault, northeastern Yucca Mountain, Nye County, Nevada
Detailed studies of trenches 14D and 14C on the Bow Ridge fault indicate two to three displacements and long recurrence intervals during the middle to late Quaternary. The main trace of the fault is marked by a thick (20--40 centimeters wide) subvertical shear zone coated with multiple carbonate-silica laminae and several generations of fine-grained fissure-fill debris. Exposed in the trenches is a vertically stacked sequence of thin (0.3--1.5 meters thick) fine-grained colluvial, alluvial, and eolian deposits that commonly contain smaller wedge-shaped units or several weakly to strongly developed buried paleosols, or both. The two to three surface-rupture events are recognized at discrete stratigraphic intervals in the sequence based on (1) incremental up-section decreases in offset of marker horizons, (b) upward terminations of shear zones, fissure fills, and fractures, and (c) the position of small scarp-derived colluvial wedges deposited adjacent to the fault above downfaulted marker horizons. Preferred estimates of the vertical displacement per event are 12 and 40 centimeters. Left-oblique striations are observed on carbonate fault laminae, which, if tectonic in origin, increase the vertical displacement by factors of 1.1 to 1.7, yielding preferred net slip displacements per event of 13 to 70 centimeters. Thermoluminescence ages of 48 {+-} 20 and 132 {+-} 23 thousand years bracket the ages of the events, which probably occurred near the bounding ages of the time interval. These age constraints suggest long, average recurrence intervals between the three events of 75 to 210 ky; the preferred values range between 100 to 140 ky. The small net cumulative displacement of two dated reference horizons yield very low fault slip rates of 0.002 to 0.007 millimeters per year; the preferred value is 0.003 millimeters per year.
Menges, C.M.; Taylor, E.M.; Vadurro, G.; Oswald, J.A.; Cress, R.; Murray, M.; Lundstrom, S.C.; Paces, J.B.; Mahan, S.A.
Soft Computing Application in Fault Detection of Induction Motor
The paper investigates the effectiveness of different patter classifier like Feed Forward Back Propagation (FFBPN), Radial Basis Function (RBF) and Support Vector Machine (SVM) for detection of bearing faults in Induction Motor. The steady state motor current with Park's Transformation has been used for discrimination of inner race and outer race bearing defects. The RBF neural network shows very encouraging results for multi-class classification problems and is hoped to set up a base for incipient fault detection of induction motor. SVM is also found to be a very good fault classifier which is highly competitive with RBF.
Konar, P.; Puhan, P. S.; Chattopadhyay, P. Dr. [Electrical Engineering Department, BESUS, Shibpur (India)
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.
Fracture Characterization Technologies | Open Energy Information
Fracture Characterization Technologies Fracture Characterization Technologies Jump to: navigation, search Geothermal ARRA Funded Projects for Fracture Characterization Technologies 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 further results","default":"","geoservice":"google","zoom":false,"width":"600px","height":"350px","centre":false,"layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","icon":"","visitedicon":"","forceshow":true,"showtitle":true,"hidenamespace":false,"template":false,"title":"","label":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"locations":[{"text":"
Pressure transient analysis for naturally fractured reservoirs
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.
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
On the fracture toughness of advanced materials
Few engineering materials are limited by their strength; rather they are limited by their resistance to fracture or fracture toughness. It is not by accident that most critical structures, such as bridges, ships, nuclear pressure vessels and so forth, are manufactured from materials that are comparatively low in strength but high in toughness. Indeed, in many classes of materials, strength and toughness are almost mutually exclusive. In the first instance, such resistance to fracture is a function of bonding and crystal structure (or lack thereof), but can be developed through the design of appropriate nano/microstructures. However, the creation of tough microstructures in structural materials, i.e., metals, polymers, ceramics and their composites, is invariably a compromise between resistance to intrinsic damage mechanisms ahead of the tip of a crack (intrinsic toughening) and the formation of crack-tip shielding mechanisms which principally act behind the tip to reduce the effective 'crack-driving force' (extrinsic toughening). Intrinsic toughening is essentially an inherent property of a specific microstructure; it is the dominant form of toughening in ductile (e.g., metallic) materials. However, for most brittle (e.g., ceramic) solids, and this includes many biological materials, it is largely ineffective and toughening conversely must be developed extrinsically, by such shielding mechanisms as crack bridging. From a fracture mechanics perspective, this results in toughening in the form of rising resistance-curve behavior where the fracture resistance actually increases with crack extension. The implication of this is that in many biological and high-strength advanced materials, toughness is developed primarily during crack growth and not for crack initiation. This is an important realization yet is still rarely reflected in the way that toughness is measured, which is invariably involves the use of single-value (crack-initiation) parameters such as the fracture toughness K{sub Ic}.
Launey, Maximilien E.; Ritchie, Robert O.
A Systematic Stochastic Petri Net Based Methodology for Transformer Fault Diagnosis and Repair Actions
Transformer fault diagnosis and repair is a complex task that includes many possible types of faults and demands special trained personnel. Moreover, the minimization of the time needed for transformer fault diagnosis and repair is an important task ... Keywords: power system reliability, stochastic petri nets, transformer fault diagnosis
P. S. Georgilakis; J. A. Katsigiannis; K. P. Valavanis; A. T. Souflaris
Fault Detection and Isolation of a Cryogenic Rocket Engine Combustion Chamber Using a Parity Space Approach
his paper presents a parity space (PS) approach for fault detection and isolation (FDI) of a cryogenic rocket engine combustion chamber. Nominal and non-nominal simulation data for three engine set points have been provided. The PS approach uses three ... Keywords: Fault Detection, Fault Isolation, Fault Diagnosis, Parity Space, Rocket Engine
Paul van Gelder; Andr� Bos
Fault-based test suite prioritization for specification-based testing
Context: Existing test suite prioritization techniques usually rely on code coverage information or historical execution data that serve as indicators for estimating the fault-detecting ability of test cases. Such indicators are primarily empirical in ... Keywords: Fault class hierarchy, Fault-based prioritization, Fault-based testing, Software testing, Specification-based testing, Test suite prioritization
Yuen Tak Yu; Man Fai Lau
A Power Transmission Line Fault Distance Estimation VLSI Chip: Design and Defect Tolerance
This paper presents a system-on-a-chip for fault detection and fault-distance-estimation for power transmission lines in the smart grid. Toward this goal we have designed and fabricated three chips: PGS4, PGS5 and PGS6, each successively more advanced ... Keywords: Smart grid, fault distance, arcing fault, system on a chip, defect tolerance, Radojevic algorithm.
E. MacLean; V. K. Jain
Application of a 3D hydraulic-fracturing simulator for design of acid-fracturing treatments
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))
On equivalence of thinning fluids used for hydraulic fracturing
The paper aims to answer the question: if and how non-Newtonian fluids may be compared in their mechanical action when used for hydraulic fracturing? By employing the modified formulation of the PKN problem we obtain its simple analytical solutions in the cases of perfectly plastic and Newtonian fluids. Since the results for shear thinning fluids are intermediate between those for these cases, the obtained equation for the fracture length suggests a criterion of the equivalence of various shear thinning fluids for the problem of hydraulic fractures. We assume fluids equivalent in their hydrofracturing action, when at a reference time they produce fractures of the same length. The equation for the fracture length translates the equivalence in terms of the hydraulic fracture length and treatment time into the equivalence in terms of the properties of a fracturing fluid (behavior and consistency indices). Analysis shows that the influence of the consistency and behavior indices on the fracture length, particle v...
Linkov, Alexander
How can we use one fracture to locate another?
Hydraulic fracturing is an important tool that helps extract fluids from the subsurface. It is critical in applications ranging from enhanced oil recovery to geothermal energy pro-duction. As the goal of fracturing is to ...
Rigid-body fracture sound with precomputed soundbanks
We propose a physically based algorithm for synthesizing sounds synchronized with brittle fracture animations. Motivated by laboratory experiments, we approximate brittle fracture sounds using time-varying rigid-body sound models. We extend methods for ...
Changxi Zheng; Doug L. James
DOE's Shale Gas and Hydraulic Fracturing Research | Department...
DOE's Shale Gas and Hydraulic Fracturing Research DOE's Shale Gas and Hydraulic Fracturing Research April 26, 2013 - 11:05am Addthis Statement of Guido DeHoratiis Acting Deputy...
Permeability Estimation From Velocity Anisotropy In Fractured Rock
Cracks in a rock mass subjected to a uniaxial stress will be preferentially closed depending on the angle between the fracture normal vectors and the direction of the applied stress. If the prestress fracture orientation ...
Gibson, Richard L., Jr.
Predicting the occurrence of open natural fractures in shale reservoirs
Prolific oil and gas production has been established from naturally fractured shale reservoirs. For example, in the last few years over 4 Tcf of gas reserves have been established within the self-sourcing Antrim Shale of the Michigan Basin. Historically, locating subsurface fracture systems essential for commercial production has proven elusive and costly. An integrated exploration approach utilizing available geologic, geophysical, and remote sensing data has successfully located naturally fractured zones within the Antrim Shale. It is believed that fracturing of the Antrim shale was a result of basement involved tectonic processes. Characteristic integrated stacked signatures of known fracture systems within the Antrim were built using gravity and magnetic data, structure maps, fracture identification logs, and Landsat imagery. Wireline fracture logs pinpointed the locations and geometries of subsurface fracture systems. Landsat imagery was interpreted to reveal surficial manifestations of subsurface structures.
Decker, A.D.; Klawitter, A.L. (Advanced Resources International, Denver, CO (United States))
Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model
Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.
Huang, Hai; Plummer, Mitchell; Podgorney, Robert
Upscaling solute transport in naturally fractured porous media with the continuous time random walk method
fracture model for multiphase ?ow in porous media. AIChEsingle- and multiphase transport in fractured porous media
Geiger, S.
Recency of Faulting and Neotectonic Framework in the Dixie Valley
of Faulting and Neotectonic Framework in the Dixie Valley of Faulting and Neotectonic Framework in the Dixie Valley Geothermal Field and Other Geothermal Fields of the Basin and Range Jump to: navigation, search OpenEI Reference LibraryAdd to library Report: Recency of Faulting and Neotectonic Framework in the Dixie Valley Geothermal Field and Other Geothermal Fields of the Basin and Range Abstract We studied the role that earthquake faults play in redistributing stresses within in the earths crust near geothermal fields. The geographic foci of our study were the sites of geothermal plants in Dixie Valley, Beowawe, and Bradys Hot Springs, Nevada. Our initial results show that the past history of earthquakes has redistributed stresses at these 3 sites in a manner to open and maintain fluid pathways critical for geothermal development. The
Aksaray And Ecemis Faults - Diapiric Salt Relationships- Relevance To The
Aksaray And Ecemis Faults - Diapiric Salt Relationships- Relevance To The Aksaray And Ecemis Faults - Diapiric Salt Relationships- Relevance To The Hydrocarbon Exploration In The Tuz Golu (Salt Lake) Basin, Central Anatolia, Turkey Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Aksaray And Ecemis Faults - Diapiric Salt Relationships- Relevance To The Hydrocarbon Exploration In The Tuz Golu (Salt Lake) Basin, Central Anatolia, Turkey Details Activities (0) Areas (0) Regions (0) Abstract: Due to activitiy of the Aksaray and Ecemis Faults, volcanic intrusion and westward movement of the Anatolian plate, diapiric salt structures were occurred in the Tuz Golu (Salt Lake) basin in central Anatolia, Turkey. With the collisions of the Arabian and Anatolian plates during the late Cretaceous and Miocene times, prominent ophiolitic
Recency Of Faulting And Neotechtonic Framework In The Dixie Valley
Of Faulting And Neotechtonic Framework In The Dixie Valley Of Faulting And Neotechtonic Framework In The Dixie Valley Geothermal Field And Other Geothermal Fields Of The Basin And Range Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Recency Of Faulting And Neotechtonic Framework In The Dixie Valley Geothermal Field And Other Geothermal Fields Of The Basin And Range Details Activities (6) Areas (3) Regions (0) Abstract: We studied the role that earthquake faults play in redistributing stresses within in the earths crust near geothermal fields. The geographic foci of our study were the sites of geothermal plants in Dixie Valley, Beowawe, and Bradys Hot Springs, Nevada. Our initial results show that the past history of earthquakes has redistributed stresses at these 3 sites in a manner to open and maintain fluid pathways critical for geothermal
Understanding Fault Characteristics And Sediment Depth For Geothermal
Understanding Fault Characteristics And Sediment Depth For Geothermal Understanding Fault Characteristics And Sediment Depth For Geothermal Exploration Using 3D Gravity Inversion In Walker Valley, Nevada Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Paper: Understanding Fault Characteristics And Sediment Depth For Geothermal Exploration Using 3D Gravity Inversion In Walker Valley, Nevada Details Activities (2) Areas (1) Regions (0) Abstract: The Southern Walker Lake Basin, situated in the Walker Lake structural domain, consists of primarily E-W directed extension along N-NNW striking normal faults. Water well drilling on the eastern slopes of the Wassuk Range, west of the city of Hawthorne, Nevada showed elevated temperatures. Two recent drill holes reaching downhole depths of more than 4000 ft give some insight to the geologic picture, but more information
Characteristics of Wind Turbines Under Normal and Fault Conditions: Preprint
This paper investigates the characteristics of a variable-speed wind turbine connected to a stiff or weak grid under normal and fault conditions and the role of reactive power compensation.
Muljadi, E.; Butterfield, C. P.; Parsons, B.; Ellis, A.
High-Resolution Aeromagnetic Survey to Image Shallow Faults,...
Number 02-384 DOI Not Provided Check for DOI availability: http:crossref.org Online Internet link for High-Resolution Aeromagnetic Survey to Image Shallow Faults, Dixie Valley...
Non-intrusive fault detection in reciprocating compressors
This thesis presents a set of techniques for non-intrusive sensing and fault detection in reciprocating compressors driven by induction motors. The procedures developed here are "non-intrusive" because they rely only on ...
Schantz, Christopher James
Discretized streams: fault-tolerant streaming computation at scale
Many "big data" applications must act on data in real time. Running these applications at ever-larger scales requires parallel platforms that automatically handle faults and stragglers. Unfortunately, current distributed stream processing models provide ...
Matei Zaharia, Tathagata Das, Haoyuan Li, Timothy Hunter, Scott Shenker, Ion Stoica
CAPRI: A Common Architecture for Distributed Probabilistic Internet Fault Diagnosis
This thesis presents a new approach to root cause localization and fault diagnosis in the Internet based on a Common Architecture for Probabilistic Reasoning in the Internet (CAPRI) in which distributed, heterogeneous ...
Lee, George J.
Dating of major normal fault systems using thermochronology-...
River detachment fault and shear zone by study of spatial gradients in 40Ar39 A and fission track cooling ages of footwall rocks and cooling histories and by comparison of...
Fusing strategies for the dual-voltage fault
This thesis focuses on the 42V - 14V fault in a dual voltage system and discusses the possibility of effective fusing. A simple model for the system had been created from technical documentation. Based on the model and the ...
Shrivastava, Rupam, 1981-
Local discriminant bases in machine fault diagnosis using vibration signals
Wavelets and local discriminant bases (LDB) selection algorithm is applied to vibration signals in a single-cylinder spark ignition engine for feature extraction and fault classification. LDB selects a complete orthogonal basis from a wavelet packet ...
R. Tafreshi; F. Sassani; H. Ahmadi; G. Dumont
Adaptive Control and Fault Detection of HVAC Equipment in Commercial...
Adaptive Control and Fault Detection of HVAC Equipment in Commercial Buildings Speaker(s): John Seem Date: February 27, 2002 - 12:00pm Location: Bldg. 90 Seminar HostPoint of...
one example being Dixie Valley, Nevada, an active normalrock at various sites: Dixie Valley, Nevada; Wasatch, Utah;20 m in parts of the Dixie Valley and Wasatch fault zones.
Microgrid Fault Protection Based on Symmetrical and Differential Current Components
Microgrid Fault Protection Based on Symmetrical and Differential Current Components Prepared.........................................................................................8 2. AEP CERTS MICROGRID .........................................................................9 ........................................................................67 #12;3 Index of Figures Figure 1: Schematic representation of the AEP CERTS microgrid
Fault Detection and Isolation in Low-Voltage DC Distribution ...
A University of Colorado research team led by Jae-Do Park has developed a fault detection and isolation scheme for a low-voltage DC-bus microgrid system, ...
Understanding Fault Characteristics And Sediment Depth For Geothermal...
of primarily E-W directed extension along N-NNW striking normal faults. Water well drilling on the eastern slopes of the Wassuk Range, west of the city of Hawthorne, Nevada...
Dynamic transient fault detection and recovery for embedded processor datapaths
As microprocessors continue to evolve and grow in functionality, the use of smaller nanometer technology scaling coupled with high clock frequencies and exponentially increasing transistor counts dramatically increases the susceptibility of transient ... Keywords: datapath, embedded, fault tolerance, reliability, soft errors
Garo Bournoutian; Alex Orailoglu
A Fault Detection and Diagnosis Method for HVAC Systems
A Fault Detection and Diagnosis Method for HVAC Systems A Fault Detection and Diagnosis Method for HVAC Systems Speaker(s): Peng Xu Date: December 2, 2002 - 12:00pm Location: Bldg. 90 There is a growing consensus that most buildings do not perform as well as intended and that faults in HVAC systems are widespread in commercial buildings. An automated fault detection and diagnosis tool for HVAC systems is being developed, based on an integrated, life-cycle, approach to commissioning and performance monitoring. The tool uses component-level HVAC equipment models implemented in the SPARK equation-based simulation environment. The models are configured using design information and component manufacturers' data and then fine-tuned to match the actual performance of the equipment by using data measured during functional tests
Fault Mapping At Coso Geothermal Area (1980) | Open Energy Information
Fault Mapping At Coso Geothermal Area (1980) Fault Mapping At Coso Geothermal Area (1980) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Fault Mapping At Coso Geothermal Area (1980) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Fault Mapping Activity Date 1980 Usefulness useful DOE-funding Unknown Exploration Basis To determine the Late Cenozoic volcanism, geochronology, and structure of the Coso Range Notes This system apparently is heated by a reservoir of silicic magma at greater than or equal to 8-km depth, itself produced and sustained through partial melting of crustal rocks by thermal energy contained in mantle-derived basaltic magma that intrudes the crust in repsonse to lithospheric extension. References Duffield, W.A.; Bacon, C.R.; Dalrymple, G.B. (10 May 1980) Late
Fluid Flow in Fractured Rock: Theory and Application
Porous Media, Pullman, WA, July 9-18,1989, and to be published in the Proceedings Fluid Flow in Fractured
Long, J.C.S.