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Environmental impact in geothermal fields
Generally, water exploitation and deep steam of geothermal fields may be cause of a pollution potential on the surface, specially by the chemical composition of geothermal water which has a high concentration of minerals, salts and heavy metals. The utilization of stable isotopes as deuterium and oxygen 18 as radioactive tracers and water origin indicators allow to know the trajectories and sources of background waters as well as possible moistures between geothermal waters and meteoric waters. Some ions such as chlorides and fluorides present solubilities that allow their register as yet long distances of their source. (Author)
Field Geothermal Volcano Azufral (CO)
The field geothermal Volcano Azufral is located to 60 km of Pasto City. It discharges waters chlorine-bicarbonates, diluted and of neuter pH. The riolitics of low k20, andesites, dacites as well as lava flows, hydro volcanic deposits due to events volcanic past and the influence of calcium like main component in the layer stamp are the main ones characteristic geologic of the volcanic area of Azufral. The layer stamp heats waters of the underground and it reacts until producing bicarbonates waters, more common type in the region. Glasses of sulfur toward the crater of the volcano are presented close to a sour lagoon. Thermal activity has been detected toward the southwest of the volcano with an area of covering of 1.47 there are, approximately. Changes in the last 14 years were determined by comparison of last chemical analysis with those obtained by INEA in 1996
Environmental isotopes of geothermal fluids in Sibayak geothermal field
Sibayak is located in a young volcanic area of North Sumatra, Indonesia. The surface manifestations such as acid springs, fumaroles and acid alterations indicate that Sibayak geothermal field is probably associated with the volcanic system. The aims of this study are to define the origin of the geothermal fluids, reservoir temperature and interactions between the volcanic system and the geothermal reservoir. Chemical composition, stable isotopes 18OH2O, 18OSO4, DH2O, 34SH2S, and 34SSO4 of water and gas samples from the geothermal surface manifestations and exploration wells are analyzed. δ18O and δD values show that the reservoir fluids of Sibayak geothermal field come from meteoric water that is recharged at an elevation of 1300-1500 masl. Geothermometers based on δ18OH2O-SO4, water chemistry (TNa-K-Ca) and gas chemistry (TH2-Ar) show similar reservoir temperatures that range from 250 to 280 deg. C. δ18O, δD isotope composition of the steam vents at the cone of Sibayak mountain, having the value of -2.9 per mille for δ18O and -44.9 per mille for δ D, shows magmatic inputs. (author)
Klamath Falls geothermal field, Oregon
Lienau, P.J.; Culver, G.; Lund, J.W.
Klamath Falls, Oregon, is located in a Known Geothermal Resource Area which has been used by residents, principally to obtain geothermal fluids for space heating, at least since the turn of the century. Over 500 shallow-depth wells ranging from 90 to 2,000 ft (27 to 610 m) in depth are used to heat (35 MWt) over 600 structures. This utilization includes the heating of homes, apartments, schools, commercial buildings, hospital, county jail, YMCA, and swimming pools by individual wells and three district heating systems. Geothermal well temperatures range from 100 to 230{degree}F (38 to 110{degree}C) and the most common practice is to use downhole heat exchangers with city water as the circulating fluid. Larger facilities and district heating systems use lineshaft vertical turbine pumps and plate heat exchangers. Well water chemistry indicates approximately 800 ppM dissolved solids, with sodium sulfate having the highest concentration. Some scaling and corrosion does occur on the downhole heat exchangers (black iron pipe) and on heating systems where the geo-fluid is used directly. 73 refs., 49 figs., 6 tabs.
Cerro Prieto geothermal field: exploration during exploitation
Geological investigations at Momotombo included photogeology, field mapping, binocular microscope examination of cuttings, and drillhole correlations. Among the geophysical techniques used to investigate the field sub-structure were: Schlumberger and electromagnetic soundings, dipole mapping and audio-magnetotelluric surveys, gravity and magnetic measurements, frequency domain soundings, self-potential surveys, and subsurface temperature determinations. The geochemical program analyzed the thermal fluids of the surface and in the wells. The description and results of exploration methods used during the investigative stages of the Momotombo Geothermal Field are presented. A conceptual model of the geothermal field was drawn from the information available at each exploration phase. The exploration methods have been evaluated with respect to their contributions to the understanding of the field and their utilization in planning further development.
Isotope study in geothermal fields in Java Island
Study in two geothermal fields, Dieng and Kamojang, in Java island by utilizing isotope technique has been carried out. Isotopic data of wells, springs and other geothermal manifestations providing informations on the recharge area of precipitation contributed to geothermal resources, flow paths and origin of geothermal fluids. The data of oxygen shift has also provided information on the characteristic the fields. (author). 8 refs, 5 figs, 3 tabs
Reservoir assessment of The Geysers Geothermal field
Thomas, R.P.; Chapman, R.H.; Dykstra, H.
Big Sulphur Creek fault zone, in The Geysers Geothermal field, may be part of a deep-seated, wrench-style fault system. Hydrothermal fluid in the field reservoir may rise through conduits beneath the five main anomalies associated with the Big Sulphur Creek wrench trend. Some geophysical anomalies (electrical resistivity and audio-magnetotelluric) evidently are caused by the hot water geothermal field or zones of altered rocks; others (gravity, P-wave delays, and possibly electrical resistivity) probably respresent the underlying heat source, a possible magma chamber; and others (microearthquake activity) may be related to the steam reservoir. A large negative gravity anomaly and a few low-resistivity anomalies suggest areas generally favorable for the presence of steam zones, but these anomalies apparently do not directly indicate the known steam reservoir. At the current generating capacity of 930 MWe, the estimated life of The Geysers Geothermal field reservoir is 129 years. The estimated reservoir life is 60 years for the anticipated maximum generating capacity of 2000 MWe as of 1990. Wells at The Geysers are drilled with conventional drilling fluid (mud) until the top of the steam reservoir is reached; then, they are drilled with air. Usually, mud, temperature, caliper, dual induction, and cement bond logs are run on the wells.
Preliminary Environmental Impact Assessment for the Geothermal Field Chachimbiro in Ecuador. A Case Comparison with Bjarnarflag Geothermal Field in Iceland
Rodas, Mario A., 1979-
The Chachimbiro geothermal area is located on the eastern flank of the Los Andes Western Mountain Range, in the province of Ibarra in Ecuador. This area is one of the many areas that had been investigated for the use of the geothermal steam, since Ecuador is the country with the most geothermal capacity among the countries that have not yet developed this energy. This study tries to determine the possible impacts of the exploration and production of this geothermal field and the implications ...
Optimization of injection scheduling in geothermal fields
Lovekin, J.
This study discusses the application of algorithms developed in Operations Research to the optimization of brine reinjection in geothermal fields. The injection optimization problem is broken into two sub-problems: (1) choosing a configuration of injectors from an existing set of wells, and (2) allocating a total specified injection rate among chosen injectors. The allocation problem is solved first. The reservoir is idealized as a network of channels or arcs directly connecting each pair of wells in the field. Each arc in the network is considered to have some potential for thermal breakthrough. This potential is quantified by an arc-specific break-through index, b/sub ij/, based on user-specified parameters from tracer tests, field geometry, and operating considerations. The sum of b/sub ij/-values for all arcs is defined as the fieldwide breakthrough index, B. Injection is optimized by choosing injection wells and rates so as to minimize B subject to constraints on the number of injectors and the total amount of fluid to be produced and reinjected. The study presents four computer programs which employ linear or quadratic programming to solve the allocation problem. In addition, a program is presented which solves the injector configuration problem by a combination of enumeration and quadratic programming. The use of the various programs is demonstrated with reference both to hypothetical data and an actual data set from the Wairakei Geothermal Field in New Zealand.
Geothermal Resource Analysis and Structure of Basin and Range Systems, Especially Dixie Valley Geothermal Field, Nevada
David Blackwell; Kenneth Wisian; Maria Richards; Mark Leidig; Richard Smith; Jason McKenna
Publish new thermal and drill data from the Dizie Valley Geothermal Field that affect evaluation of Basin and Range Geothermal Resources in a very major and positive way. Completed new geophysical surveys of Dizie Valley including gravity and aeromagnetics and integrated the geophysical, seismic, geological and drilling data at Dizie Valley into local and regional geologic models. Developed natural state mass and energy transport fluid flow models of generic Basin and Range systems based on Dizie Valley data that help to understand the nature of large scale constraints on the location and characteristics of the geothermal systems. Documented a relation between natural heat loss for geothermal and electrical power production potential and determined heat flow for 27 different geothermal systems. Prepared data set for generation of a new geothermal map of North American including industry data totaling over 25,000 points in the US alone.
Pilot fruit drier for Los Azufres geothermal field, Michoacan, Mexico
Lund, J.W.
Comision Federal de Electricidad (CFE) has a Division in charge of the exploration of a geothermal reservoir located in Los Azufres, State of Michoacan. At present, CFE is only using the steam of the wells and rejecting the hot water that comes off associated with the steam. Based on a trip to the Los Azufres geothermal field in December of 1992, a design for a pilot geothermal fruit drier was undertaken for CFE. The details of the geothermal field and the local fruit production are detailed.
Design of Steam Gathering System for Menengai Geothermal Field, Kenya
Onyango, Stephen Odhiambo, 1980-
Utilizing high temperature geothermal resources for power generation requires design of steam gathering system to transport geothermal fluids. The aim of this project is develop a model that can be used to optimize the steam gathering and the re-injection systems in Menengai geothermal field. The objective function includes the capital investment and the operational cost. The constraints are the steam and water velocity and the upward slope of the two phase flow pipelines. To test the model, ...
Structural investigations of Great Basin geothermal fields: Applications and implications
Faulds, James E [Nevada Bureau of Mines and Geology, Univ. of Nevada, Reno, NV (United States); Hinz, Nicholas H. [Nevada Bureau of Mines and Geology, Univ. of Nevada, Reno, NV (United States); Coolbaugh, Mark F [Great Basin Center for Geothermal Energy, Univ. of Nevada, Reno, NV (United States)
Because fractures and faults are commonly the primary pathway for deeply circulating hydrothermal fluids, structural studies are critical to assessing geothermal systems and selecting drilling targets for geothermal wells. Important tools for structural analysis include detailed geologic mapping, kinematic analysis of faults, and estimations of stress orientations. Structural assessments are especially useful for evaluating geothermal fields in the Great Basin of the western USA, where regional extension and transtension combine with high heat flow to generate abundant geothermal activity in regions having little recent volcanic activity. The northwestern Great Basin is one of the most geothermally active areas in the USA. The prolific geothermal activity is probably due to enhanced dilation on N- to NNE-striking normal faults induced by a transfer of NW-directed dextral shear from the Walker Lane to NW-directed extension. Analysis of several geothermal fields suggests that most systems occupy discrete steps in normal fault zones or lie in belts of intersecting, overlapping, and/or terminating faults. Most fields are associated with steeply dipping faults and, in many cases, with Quaternary faults. The structural settings favoring geothermal activity are characterized by subvertical conduits of highly fractured rock along fault zones oriented approximately perpendicular to the WNW-trending least principal stress. Features indicative of these settings that may be helpful in guiding exploration for geothermal resources include major steps in normal faults, interbasinal highs, groups of relatively low discontinuous ridges, and lateral jogs or terminations of mountain ranges.
Environmental isotope techniques in geothermal exploration with special reference to Indian geothermal fields (Paper No. IT-05)
Environmental isotopes have acted as natural tracers to arrive at the origin of geothermal fluid components, their areas of recharge, their flow pattern and their interaction with the reservoir rocks and shallow groundwater. Also, isotope studies have thrown light on the residence times and base temperatures of the geothermal fluids and on the responses of geothermal fields to development and exploitation. These techniques are briefly described. Studies in Indian geothermal fields are mentioned. (author). 8 refs., 3 figs
Development of an Enhanced Two-Phase Production System at the Geysers Geothermal Field; FINAL
A method was developed to enhance geothermal steam production from two-phase wells at THE Geysers Geothermal Field. The beneficial result was increased geothermal production that was easily and economically delivered to the power plant
The Geothermal Field Camp: Capacity building for geothermal energy systems in Indonesia
Moeck, I.; Sule, R.; Saptadji, N. M.; Deon, F.; Herdianita, N. R.; Jolie, E.; Suryantini, N.; Erbas, K.
In July 2011, the first geothermal field camp was hold on Java/Indonesia near the city Bandung south of the volcanic field Tangkuban Perahu. The course was organized by the Institut Teknologie Bandung (ITB) and International Centre for Geothermal Research (ICGR) of the German Centre of Geosciences (GFZ). The purpose of the Geothermal Field Camp is to combine both field based work and laboratory analysis to ultimately better understand the data collected in field and to integrate data gained by various disciplines. The training belongs to a capacity building program for geothermal energy systems in Indonesia and initially aims to train the trainers. In a later stage, the educational personal trained by the Geothermal Field Camp shall be able to hold their individual Geothermal Field Camp. This is of special interest for Indonesia where the multitude of islands hindered a broad uniform education in geothermal energy systems. However, Indonesia hold the largest geothermal potential worldwide and educated personal is necessary to successfully develop this huge potential scattered over region in future. The interdisciplinary and integrative approach combined with field based and laboratory methodologies is the guiding principle of the Geothermal Field Camp. Tangkuban Perahu was selected because this field allows the integration of field based structural geological analysis, observation and sampling of geothermal manifestations as hot springs and sinters and ultimately of structural geology and surface geochemistry. This innovative training introduces in methods used in exploration geology to study both, fault and fracture systems and fluid chemistry to better understand the selective fluid flow along certain fractures and faults. Field geology covered the systematic measurement of faults and fractures, fault plane and fracture population analysis. In addition, field hydro-geochemistry focused on sampling techniques and field measurements onsite. Subsequent data analysis
Radiotracer test in Kamojang geothermal field, West Java, Indonesia
A tritium radiotracer study has been carried out at Kamojang geothermal field. Tritium tracer has been added to reinjection water in a production well, and then tritium content has been monitored in the surrounding production wells
The Ahuachapan geothermal field, El Salvador: Reservoir analysis
Aunzo, Z.; Bodvarsson, G.S.; Laky, C.; Lippmann, M.J.; Steingrimsson, B.; Truesdell, A.H.; Witherspoon, P.A. (Lawrence Berkeley Lab., CA (USA); Icelandic National Energy Authority, Reykjavik (Iceland); Geological Survey, Menlo Park, CA (USA); Lawrence Berkeley Lab., CA (USA))
These are appendices F through I of the Ahuachapan Geothermal Field Reservoir Analysis. The volume contains: well logs, water chemistry plots, gas chemistry plots, temperature plots, and flow plots. (JEF)
Symposium in the field of geothermal energy
Ramirez, Miguel; Mock, John E.
Mexico and the US are nations with abundant sources of geothermal energy, and both countries have progressed rapidly in developing their more accessible resources. For example, Mexico has developed over 600 MWe at Cerro Prieto, while US developers have brought in over 2000 MWe at the Geysers. These successes, however, are only a prologue to an exciting future. All forms of energy face technical and economic barriers that must be overcome if the resources are to play a significant role in satisfying national energy needs. Geothermal energy--except for the very highest grade resources--face a number of barriers, which must be surmounted through research and development. Sharing a common interest in solving the problems that impede the rapid utilization of geothermal energy, Mexico and the US agreed to exchange information and participate in joint research. An excellent example of this close and continuing collaboration is the geothermal research program conducted under the auspices of the 3-year agreement signed on April 7, 1986 by the US DOE and the Mexican Comision Federal de Electricidad (CFE). The major objectives of this bilateral agreement are: (1) to achieve a thorough understanding of the nature of geothermal reservoirs in sedimentary and fractured igneous rocks; (2) to investigate how the geothermal resources of both nations can best be explored and utilized; and (3) to exchange information on geothermal topics of mutual interest.
Characterization of deep ground geothermal field in Jiahe Coal Mine
Zhang Yi; Guo Dongming; He Manchao; Jiang Yaodong; Yang Qing
Research into the characteristics of geothermal fields is important for the control of heat damage in mines.Based on measured geothermal data of boreholes from -200 m to -1200 m in a Jiahe Coal Mine,we demonstrate non-linear but increasing relations of both geo-temperatures and geothermal gradients with increases depth.Numerically,we fitted the relationship between geo-temperatures and depth,a first-order exponential decay curve,formulated as:T(h) - -4.975 + 23.08 × exp(-h/1736.1 ).
Investigations of deep resistivity structures at the Wairakei geothermal field
Bibby, Hugh M.; Risk, George F.; Grant Caldwell, T.; Heise, Wiebke [GNS Science, P.O. Box 30368, Lower Hutt (New Zealand)
The Wairakei geothermal field was the proving ground for the use of electrical resistivity methods for geothermal exploration. At this site it was first demonstrated that a large contrast in resistivity existed between geothermal ground and the cold surroundings. Within the top 500 m of the geothermal field, low-resistivity (5-10 {omega}m) reflects the effects of both the hot saline water in the pore spaces and the conductive rock-matrix. The first surveys at Wairakei used a Wenner array (a {proportional_to}550 m) to measure the resistivity values along tracks throughout the field; contour maps of the resistivities were used to estimate the lateral extent of the geothermal waters at a few hundred metres depth. In the late 1960s the Wenner array was superseded by the Schlumberger array (AB/2 = 500 m and 1000 m), which enabled deeper penetration and better definition of the extent of the geothermal waters. These early surveys showed that the bounds of the geothermal waters were often sharp, leading to the concept that a 'resistivity boundary' could be defined for New Zealand's liquid-dominated geothermal fields. As new methods of measuring electrical structure with greater precision became available, Wairakei was often chosen as the testing ground. In 1982, a deep penetrating tensor bipole-dipole survey was made over the northern part of the field to provide close-spaced data across the boundary, leading to a better definition of the boundary and its change with depth. A similar survey over the eastern edge of the field revealed a very sharp boundary with an apparent correlation between its location and a deeper caldera structure. The first application of tensor time-domain resistivity (tensor LOTEM) was made across the north-western edge of Wairakei in 1997 giving both a detailed image of the boundary and showing that it was possible to trace geological structures within the geothermal field. The most commonly used method for resistivity surveying in
Structural Controls of the Tuscarora Geothermal Field, Elko County, Nevada
Dering, Gregory M.
Detailed geologic mapping, structural analysis, and well data have been integrated to elucidate the stratigraphic framework and structural setting of the Tuscarora geothermal area. Tuscarora is an amagmatic geothermal system that lies in the northern part of the Basin and Range province, ˜15 km southeast of the Snake River Plain and ˜90 km northwest of Elko, Nevada. The Tuscarora area is dominated by late Eocene to middle Miocene volcanic and sedimentary rocks, all overlying Paleozoic metasedimentary rocks. A geothermal power plant was constructed in 2011 and currently produces 18 MWe from an ˜170°C reservoir in metasedimentary rocks at a depth of 1740 m. Analysis of drill core reveals that the subsurface geology is dominated to depths of ˜700-1000 m by intracaldera deposits of the Eocene Big Cottonwood Canyon caldera, including blocks of basement-derived megabreccia. Furthermore, the Tertiary-Paleozoic nonconformity within the geothermal field has been recognized as the margin of this Eocene caldera. Structural relations combined with geochronologic data from previous studies indicate that Tuscarora has undergone extension since the late Eocene, with significant extension in the late Miocene-Pliocene to early Pleistocene. Kinematic analysis of fault slip data reveal an east-west-trending least principal paleostress direction, which probably reflects an earlier episode of Miocene extension. Two distinct structural settings at different scales appear to control the geothermal field. The regional structural setting is a 10-km wide complexly faulted left step or relay ramp in the west-dipping range-bounding Independence-Bull Run Mountains normal fault system. Geothermal activity occurs within the step-over where sets of east- and west-dipping normal faults overlap in a northerly trending accommodation zone. The distribution of hot wells and hydrothermal surface features, including boiling springs, fumaroles, and siliceous sinter, indicate that the geothermal
Paleotemperature analysis of Aliaga (Izmir, Turkey) geothermal field
Sengueler, I.; Sener, M.; Koek, M.V.
Mineralogical and organopetrographic analysis were carried out on core samples of four geothermal wells from the Aliaga geothermal field located in western Turkey. Whole rock mineralogy and clay minerals were determined, and thermal maturity of the different levels of the formation was defined by means of vitrinite reflectance measurements. The measured maturity gradients compiled from analytical data for four wells and outcrops ranged from low to very high values.
Paleotemperature analysis of Aliaga (Izmir, Turkey) geothermal field
Senguler, I.; Sener, M.; Kok, M.V.
Mineralogical and organopetrographic analysis were carried out on core samples of four geothermal wells from the Aliaga geothermal field located in western Turkey. Whole rock mineralogy and clay minerals were determined, and thermal maturity of the different levels of the formation was defined by means of vitrinite reflectance measurements. The measured maturity gradients compiled from analytical data for four wells and outcrops ranged from low to very high values. (author)
Geothermal reservoir at Tatapani Geothermal field, Surguja district, Madhya Pradesh, IN
Pitale, U.L.; Sarolkar, P.B.; Rawat, H.S.; Shukia, S.N.
The Tatapani Geothermal field, located on the Son-Narmada mega lineament is one of the most intense geothermal manifestation, with hot spring temperature of 98°c. in Central India. 21 Exploratory and thermal gradient boreholes followed by 5 production wells for proposed 300 KWe binary cycle power plant, have revealed specific reservoir parameters of shallow geothermal reservoir of 110°c in upper 350 m of geothermal system and their possible continuation to deeper reservoir of anticipated temperature of 160 ± 10°c. Testing of five production wells done by Oil and Natural Gas Corporation concurrently with drilling at different depths and also on completion of drilling, have established feeder zones of thermal water at depth of 175-200 m, 280-300 m, maximum temperature of 112.5°c and bottom hole pressure of 42 kg/cm². Further interpretation of temperature and pressure profiles, injection test, well head discharges and chemical analysis data has revealed thermal characteristics of individual production wells and overall configuration of .thermal production zones with their permeability, temperature, and discharge characteristics in the shallow thermal reservoir area. Well testing data and interpretation of reservoir parameters therefrom, for upper 350 m part of geothermal system and possible model of deeper geothermal reservoir at Tatapani have been presented in the paper.
Tracers technique development in geothermal and oil fields in Indonesia
Indonesia is one of the oil countries that have more than 40 % of the world's geothermal reserves. Geothermal development has amounted to 807 MW including several fields (Kamojang, dieng salak, Wayang windu, Darajat Sibayak and lahendong) from 20,000 MW reserves. In several locations in Sumatra there are many oil fields under secondary production. At present, they are starting to exploit possibilities using EOR technology. Tracer technology is an alternative to determine interconnection between wells and mass recovery for steam or oil management. Tracer return in wells production could be used to calculate optimization of water re-injection and various useful parameters including swept volume between well pairs. Some radiotracers like tritiated water HTO, iodide as 125I- (or 131I- in some cases) and cobalthexacyanide as for instance 60Co(CN)63- could be considered as suitable tracers for reservoir systems. HTO will be injected into geothermal reservoirs under different conditions: Vapour dominated (Kamojang) and two phase systems (Lahendong). Radiotracers of iodide will be injected to the liquid dominated system of the geothermal field (Salak). Also HTO and radiolabelled Co(CN)63- will be injected simultaneously in an oilfield under secondary recovery. Data interpretation using userfriendly software (Iceboc, etc.) will give maximum technology contribution to geothermal fluids and oil field management
Stable isotope study in geothermal fields in Kamojang and Dieng, Java Island
A survey of the stable isotope composition of geothermal sources was initiated at several geothermal fields on the island of Java during 1988-1990. A further study was carried out in two geothermal fields, Kamojang and Dieng, which was approximately 400 km apart. The study was intended to provide an isotope database to monitor geothermal evolution resulting from exploitation and to identify the recharge area of the geothermal system. 1 fig
Some comments on the La Primavera geothermal field, Mexico
Dominguez A, B.; Lippmann, M.J.
The La Primavera geothermal field is located about 20 km west of the city of Guadalajara, Jalisco, in the western part of the Mexican Neovolcanic Axis. Initial results of five deep exploration wells (down to 2000 m depth) were very promising; measured downhole temperatures exceed 300/sup 0/C. During production, however, downhole temperatures dropped, and the chemistry of the fluids changed. The analysis of geologic, mineralogic, geochemical, and well completion data indicate that colder fluids flow down the wellbore from shallower aquifers cooling the upper zones of the geothermal reservoir. This problem is attributed to inadequate well completions. Doubts have arisen about continuing the exploration of the field because of the somewhat disappointing drilling results. However, a more thorough analysis of all available data indicates that a good geothermal prospect might exist below 3000 m, and that it could be successfully developed with appropriately located and completed wells.
Geothermal Reservoir Characterization for Steam Field Management in Kamojang Geothermal Field-West Java
Z. Abidin
Full Text Available Kamojang is the first geothermal field in Indonesia with a vapor dominated system reservoir. Kamojang has been exploited for over 20 years producing about 1100 tons/hour of steam which is equivalent to 140 Mwe electricity energy. This research is aimed to study the reservoir character after 20 years of exploitation and to investigate the effect of reinjection as a artificial recharge for steam input in the future and also the nature of secondary processes in the reservoir using isotope geochemistry tools. The research is conducted by natural isotopes (18O, 2H and 3H analysis of many sources of water (meteoric, cold spring, fumaroles and shallow groundwater in the surrounding of Kamojang field and also fluid reservoir to establish fluid reservoir origins and isotopic composition. Gas analysis and isotopes monitoring on the 25 production wells have been conducted every 2-3 years intervals for more than 10 years to investigate the effect of exploitation to the reservoir performance. Tritium radiotracer test with 370 GBq (10 Ci activity was conducted at the KMJ 15 reinjection well to determine qualitatively and quantitatively the flow of reinjection water to its surrounding producing well (KMJ 11, 14, 17, 18, 26, 17 and 30. Data interpretation and evaluation to determine reinjection water mass recovery and cooling prediction modeling were conducted using ICEBOX program package (TRINV and TRCOOL. Interpretation and evaluation of data concluded that reservoir fluid of Kamojang geothermal field was originated from meteoric water which infiltrated through fault structures at elevation of 1350 m –1650 m above sea level. There is no evidence that the fluid was originated from magmatic water. Reservoir fluid moved both laterally and vertically (deep fluid with lateral fluid movement from west to the east. The isotope data analysis indicated there is water entry in west-northwest reservoir boundary. Water entry gradually moved from northwest to the
Geothermal Reservoir Characterization For Steam Field Management In Kamojang Geothermal Field-West Java
Kamojang is the first geothermal field in Indonesia with a vapor dominated system reservoir. Kamojang has been exploited for over 20 years producing about 1100 tons/hour of steam which is equivalent to 140 Mwe electricity energy. This research is aimed to study the reservoir character after 20 years of exploitation and to investigate the effect of reinjection as a artificial recharge for steam input in the future and also the nature of secondary processes in the reservoir using isotope geochemistry tools. The research is conducted by natural isotopes (18O, 2H and 3H) analysis of many sources of water (meteoric, cold spring, fumaroles and shallow groundwater) in the surrounding of Kamojang field and also fluid reservoir to establish fluid reservoir origins and isotopic composition. Gas analysis and isotopes monitoring on the 25 production wells have been conducted every 2-3 years intervals for more than 10 years to investigate the effect of exploitation to the reservoir performance. Tritium radiotracer test with 370 GBq (10 Ci) activity was conducted at the KMJ 15 reinjection well to determine qualitatively and quantitatively the flow of reinjection water to its surrounding producing well (KMJ 11, 14, 17, 18, 26, 17 and 30). Data interpretation and evaluation to determine reinjection water mass recovery and cooling prediction modeling were conducted using ICEBOX program package (TRINV and TRCOOL). Interpretation and evaluation of data concluded that reservoir fluid of Kamojang geothermal field was originated from meteoric water which infiltrated through fault structures at elevation of 1350 m -1650 m above sea level. There is no evidence that the fluid was originated from magmatic water. Reservoir fluid moved both laterally and vertically (deep fluid) with lateral fluid movement from west to the east. The isotope data analysis indicated there is water entry in west-northwest reservoir boundary. Water entry gradually moved from northwest to the southeast (through
The Hydrogeochemistry of Qingshui Geothermal Field, Northeastern Taiwan.
Yu-Wen, Chen; Cheng-Kuo, Lin; Wayne, Lin; Yu-Te, Chang; Pei-Shan, Hsieh
The Qingshui geothermal field is located at the upstream valley of Lanyang Creek, northeastern Taiwan. It is renowned as a geothermal field. The previous studies demonstrated a higher geothermal gradient, 100oC/km warmer than a normal geotherm. However, Qingshui geothermal field has not been well developed due to the higher mining costs. In the recent years, the Taiwan government has been focusing on developing alternative and renewable energy and initiated a 10 year project, Nation Energy Program. This study is part of this project In general, it is very difficult to collect deep downhole samples without considerable change of hydro- and gas- chemistry of water under high temperature and pressure. A new sampling tool, GTF Sampler, was designed by the research team, Green Energy and Environment Laboratories, Industrial Technology Research Institute. This tool can simultaneously collect high quality geothermal water and gas sample and moreover, the sampling depth can reach up to 800 meters. Accordingly, a more accurate measurements can be conducted in the laboratory. In this study, 10 geothermal samples were collected and measured. The results demonstrate that geothermal water samples are characterized with Na(K)-HCO3 water type and located at the mature water area in Giggenbach Na-K-Mg diagram. Several geothermometers, including silica and cation geothermometry, were used to estimate potential temperature in the geothermal reservoir systems. In general, the geothermoters of Na-K and Na-K-Ca obtain reservoir temperatures between 120-190oC and 130-210oC, respectively, but the silica geothermometer indicates a lower reservoir temperature between 90 and 170oC. There is no big difference among them. It is worth to note that all calculated temperatures are lower than those of in-situ downhole measurements; therefore, more detailed and advanced researches would be needed for the inconsistency. To examine the argument about igneous heat source in the previous studies, rare
Radon studies for extending Los Azufres geothermal energy field in Mexico
Los Azufres is a 98 MW producing geothermal energy field situated in the Mexican volcanic belt at the west part of the country. Recently, hydrothermal activity and geochemical analysis of geothermal fluids from the north part of the geothermal field gave indications of a possible geothermal-production area, similar to the already producing field. In order to investigate the activity of geological structures, which are considered the means of geothermal fluids transporters, radon mapping was carried out using sets of 240 LR-115 detectors in the area of interest. Radon values higher than 10 kBq m-3 were considered anomalous and indicative of geothermal anomalies
Radon studies for extending Los Azufres geothermal energy field in Mexico
Tavera, L; Camacho, M E; Chavez, A; Pérez, H; Gómez, J
Los Azufres is a 98 MW producing geothermal energy field situated in the Mexican volcanic belt at the west part of the country. Recently, hydrothermal activity and geochemical analysis of geothermal fluids from the north part of the geothermal field gave indications of a possible geothermal-production area, similar to the already producing field. In order to investigate the activity of geological structures, which are considered the means of geothermal fluids transporters, radon mapping was carried out using sets of 240 LR-115 detectors in the area of interest. Radon values higher than 10 kBq m sup - sup 3 were considered anomalous and indicative of geothermal anomalies.
DC resistivity at the Ahuachapan geothermal field, El Salvador
Fink, J.B.; de la Fuente D., M.; Rodriquez, C.; Cash, D.J.; Gerety, M.
Deep dc resistivity surveying has been performed at the Ahuachapan Geothermal Field in western El Salvador. The field lies on the north base if the volcanic range that runs the length of the country and is the site of a significant active geothermal powerplant. The technical purpose of the surveying was to assess the geophysical properties of the geothermal regime around the existing field. The survey was carried out as a colinear dipole-dipole survey using dipole spacings of 500m and 1000m, and dipole separations of up to fourteen dipole lengths. Results included (1) the observation that the geothermal reservoir was not readily detectable due to surface lithologic changes and extensive cultural effects, (2) the hydrothermally altered areas are readily recognized by their low resistivities, (3) local lithologies appear to be mappable based on their in situ resistivities, (4) the greater field logistical convenience of the shorter 500m dipole spacings is negated by the increase in topographic effects, and (5) if appropriate dipole separations are used, there is no need to run surveys of both 500 and 1000 meter dipole spacings to gather shallow and deep information. 7 figs.
Temperature distribution in the Cerro Prieto geothermal field
Castillo B, F.; Bermejo M, F.J.; Domiguez A, B.; Esquer P, C.A.; Navarro O, F.J.
A series of temperature and pressure logs and flow rate measurements was compiled for each of the geothermal wells drilled to different reservoir depths between October 1979 and December 1980. Based on the valuable information obtained, a series of graphs showing the thermal characteristics of the reservoir were prepared. These graphs clearly show the temperature distribution resulting from the movement of fluids from the deep regions toward the higher zones of the reservoir, thus establishing more reliable parameters for locating new wells with better production zones. Updated information based on data from new deep wells drilled in the geothermal field is presented here. This new information does not differ much from earlier estimates and theories. However, the influence of faulting and fracturing on the hydrothermal recharge of the geothermal reservoir is seen more clearly.
A Reservoir Assessment of the Geysers Geothermal Field
Thomas, Richard P.; Chapman, Rodger H.; Dykstra, Herman; Stockton, A.D.
Big Sulphur Creek fault zone, in The Geysers Geothermal field, may be part of a deep-seated, wrench-style fault system. Hydrothermal fluid reservoir may rise through conduits beneath the five main anomalies associated with the Big Sulphur Creek wrench trend. Upon moderately dipping, fracture network. Condensed steam at the steep reservoir flank drains back to the hot water table. These flanks are defined roughly by marginally-producing geothermal wells. Field extensions are expected to be on the southeast and northwest. Some geophysical anomalies (electrical resistivity and audio-magnetotelluric) evidently are caused by the hot water geothermal field or zones of altered rocks; others (gravity, P-wave delays, and possibly electrical resistivity) probably represent the underlying heat source, a possible magma chamber; and others (microearthquake activity) may be related to the steam reservoir. A large negative gravity anomaly and a few low-resitivity anomalies suggest areas generally favorable for the presence of steam zones, but these anomalies apparently do not directly indicate the known steam reservoir. Monitoring gravity and geodetic changes with time and mapping microearthquake activity are methods that show promise for determining reservoir size, possible recharge, production lifetime, and other characteristics of the known stream field. Seismic reflection data may contribute to the efficient exploitation of the field by identifying fracture zones that serve as conduits for the steam. (DJE-2005)
Some Comments on the La Primavera Geothermal Field, Mexico
A., Bernardo Dominguez; Lippmann, Marcelo J.
The La Primavera geothermal field is located about 20 km west of the city of Guadalajara, Jalisco, in the western part of the Mexican Neovolcanic Axis. Initial results of five deep exploration wells (down to 2000 m depth) were very promising; measured downhole temperatures exceed 300{degrees}C. During production, however, downhole temperatures dropped, and the chemistry of the fluids changed. The analysis of geologic, mineralogic, geochemical, and well completion data indicate that colder fluids flow down the wellbore from shallower aqifers cooling the upper zones of the gothermal reservoir. This problem is attributed to inadequate well completions. Doubts have arisen about continuing the exploration of the field because of the somewhat disappointing drilling results. However, a more thorough analysis of all available data indicates that a good geothermal prospect might exist below 3000 m, and that it could be successfully developed with appropriately located and completed wells.
Development case histories: Tongonan and Palinpinon geothermal fields, Philippines
The background on the general scenario of energy resource development in the country is described. Highlights of the exploration history of the Tongonan and Palinpinon geothermal fields in the Philippines are then presented. This is discussed in conjunction with the strategies and policies taken in the development of each field. Finally, the common policies and contrasting development strategies are compared and evaluated. The conclusion derived is that the development strategy decisions at Tongonan are influenced by the regional power demand, topography, and the large extent of the resource. In contrast, the development at Palinpinon is less constrained by the external influence of regional power needs, but, instead, is significantly dominated by the limitations imposed by the rugged terrain and the physical characteristics of the resource area. Such comparison demonstrates the site-specific nature of geothermal development. (auth.). 8 figs.; 2 refs
Mathematical aspects of stress field simulations in deep geothermal reservoirs
Augustin, Matthias
This report gives an insight into basics of stress field simulations for geothermal reservoirs. The quasistatic equations of poroelasticity are deduced from constitutive equations, balance of mass and balance of momentum. Existence and uniqueness of a weak solution is shown. In order of to find an approximate solution numerically, usage of the so–called method of fundamental solutions is a promising way. The idea of this method as well as a sketch of how convergence may be prov...
The Geysers Geothermal Field Update1990/2010
Brophy, P.; Lippmann, M.; Dobson, P.F.; Poux, B.
In this report, we have presented data in four sections: (1) THE GEYSERS HISTORICAL UPDATE 1990-2010 - A historical update of the primary developments at The Geysers between 1990 and 2010 which uses as its start point Section IIA of the Monograph - 'Historical Setting and History of Development' that included articles by James Koenig and Susan Hodgson. (2) THE GEYSERS COMPREHENSIVE REFERENCE LIST 1990-2010 - In this section we present a rather complete list of technical articles and technical related to The Geysers that were issued during the period 1990-2010. The list was compiled from many sources including, but not limited to scientific journals and conference proceedings. While the list was prepared with care and considerable assistance from many geothermal colleagues, it is very possible that some papers could have been missed and we apologize to their authors in advance. The list was subdivided according to the following topics: (1) Field characterization; (2) Drilling; (3) Field development and management; (4) Induced seismicity; (5) Enhanced Geothermal Systems; (6) Power production and related issues; (7) Environment-related issues; and (8) Other topics. (3) GRC 2010 ANNUAL MEETING GEYSERS PAPERS - Included in this section are the papers presented at the GRC 2010 Annual Meeting that relate to The Geysers. (4) ADDITIONAL GEYSERS PAPERS 1990-2010 - Eighteen additional technical papers were included in this publication in order to give a broad background to the development at The Geysers after 1990. The articles issued during the 1990-2010 period were selected by colleagues considered knowledgeable in their areas of expertise. We forwarded the list of references given in Section 2 to them asking to send us with their selections with a preference, because of limited time, to focus on those papers that would not require lengthy copyright approval. We then chose the articles presented in this section with the purpose of providing the broadest possible
Interstratified Illite/Montmorillonite in Kamojang Geothermal Field, Indonesia
D. F. Yudiantoro
Full Text Available DOI: 10.17014/ijog.v8i4.167Kamojang geothermal field located in West Java Province, falls under the Pangkalan Subregency, Bandung Regency. The researched area is a geothermal field located in the Quaternary volcanic caldera system of about 0.452 to 1.2 Ma. The volcanic activity generated hydrothermal fluids, interacting with rocks producing mineral alteration. The minerals formed in the areas of research are interstratified illite/montmorillonite (I/M. Analyses to identify interstratified I/M have been performed by X-ray diffraction using ethylene glycol, while the determination of the type and percentage of interstratified I/M was based on the calculation method of Watanabe. The methodology was applied on core and cutting samples from Wells KMJ-8, 9, 11, 13, 16, 23, 49, 51, and 54. The result of analysis of the samples shows that the type of clay is interstratified illite/montmorillonite and the minerals are formed at temperatures ranging from 180 to 220° C. The type of interstratified I/M in the studied area is S = 0 and S = 1. The percentage of illite type S = 0 is between 20 - 35% illite, whereas type S = 1 has about 45 - 72% illite. Along with the increasing depth, the percentage of illite is getting greater. This is consistent with the vertical distribution of temperature which increases according to the depth. This correlation results in an interpretation that the upflow zone of the geothermal reservoir is located in the centre of the Kamojang geothermal field.
Microbial community profiling of the Chinoike Jigoku ("Blood Pond Hell") hot spring in Beppu, Japan: isolation and characterization of Fe(III)-reducing Sulfolobus sp. strain GA1.
Masaki, Yusei; Tsutsumi, Katsutoshi; Hirano, Shin-Ichi; Okibe, Naoko
Chinoike Jigoku ("Blood Pond Hell") is located in the hot spring town of Beppu on the southern island of Kyushu in Japan, and is the site of a red-colored acidic geothermal pond. This study aimed to investigate the microbial population composition in this extremely acidic environment and to isolate/characterize acidophilic microorganism with metal-reducing ability. Initially, PCR (using bacteria- and archaea-specific primers) of environmental DNA samples detected the presence of bacteria, but not archaea. This was followed by random sequencing analysis, confirming the presence of wide bacterial diversity at the site (123 clones derived from 18 bacterial and 1 archaeal genera), including those closely related to known autotrophic and heterotrophic acidophiles (Acidithiobacillus sp., Sulfobacillus sp., Alicyclobacillus sp.). Nevertheless, successive culture enrichment with Fe(III) under micro-aerobic conditions led to isolation of an unknown archaeal organism, Sulfolobus sp. GA1 (with 99.7% 16S rRNA gene sequence identity with Sulfolobus shibatae). Unlike many other known Sulfolobus spp., strain GA1 was shown to lack sulfur oxidation ability. Strain GA1 possessed only minor Fe(II) oxidation ability, but readily reduced Fe(III) during heterotrophic growth under micro-aerobic conditions. Strain GA1 was capable of reducing highly toxic Cr(VI) to less toxic/soluble Cr(III), demonstrating its potential utility in bioremediation of toxic metal species. PMID:27208660
Radon as a guide to geothermal exploration. The case of Chipilapa geothermal field in El Salvador
During the months September 1990 until January 1991 was realized in Chipilapa Geothermal field a Radon study utilizing nitrocelullose films as detector. The concentration of average Radon obtained was 125 pCi/l with a standard deviation of 51. As natural background of Radon concentration in the study area was establish a value of 50 pCi/l so it permitted to determine as an anomaly those ones concentrations upper than 100 pCi/l. The obtained results show interest zone the central and southwest of Chipilapa area, so also at east of Cuyanausul fault and along Agua Shuca fault. (Author)
Drilling of geothermal well in Onikobe geothermal field and developping Oguni geothermal field. Onikobe oyobi Oguni chiiki ni okeru chinetsusei kussaku ni tsuite
Abe, S.; Kurishima, S. (Electric Power Development Co. Ltd., Tokyo (Japan)); Mezaki, Y.
This paper describes the Onikobe Geothermal Power Plant in Miyagi Prefecture developed by the Electric Power Source Development Co., Ltd., and the current development state of drilling geothermal wells at the Oguni geothermal field in Kumamoto Prefecture. The Onikobe area has alteration zone distributed widely, with a clayey layer at a depth between 80 m and 150 m, and steam reservoir layers at depths around 300 m and deeper than 800 m. The production wells in shallow layers were drilled with great attentions because the layer down to about 300 m, which is a steam layer, has an extremely high underground temperature rise rate and incessant danger of spontaneous explosions. Drilling deep slanted wells used an increased number of casing pipes. The slanted drilling has dealt with the high temperatures starting at shallow depths by beginning the hole bending at a depth as unexceptionally shallow as 80 meters. The Oguni area presented no special problems in geothermal well drilling. However, because of employing a base system in which excavation locations are limited as a result of highly undulated topography and road conditions, almost all wells were drilled slanted. 21 refs., 8 figs., 13 tabs.
Optimization of Electrical Power Production from High Temperature Geothermal Fields with respect to Silica Scaling Problems
Nugroho, Andi Joko, 1977-
Silica scaling is an obstacle in the use of geothermal fluid from high temperature fields. The potential issue of silica deposition rises with increasing resource temperature. A single flash condensing system is the most common energy conversion system for utilizing geothermal fluid from high temperature fields, mainly due to its smallest possibility of silica precipitation. This thesis investigates the possibility of optimizing the employment of geothermal fluid from high temperature fields ...
Hydrothermal surface alteration in the Copahue Geothermal Field (Argentina)
Mas, Graciela R.; Mas, Luis C.; Bengochea, Leandro
In the area of the Copahue Geothermal Field, there are five active geothermal manifestations, which mainly consist of fumaroles, hot springs and mud pots. Four of these manifestations are located in Argentina: Las Máquinas, Termas de Copahue, Las Maquinitas and El Anfiteatro, and the fifth on the Chilean side: Chancho Co. All of them present a strong acid sulfate country rock alteration, characterized by the assemblage alunite + kaolinite + quartz + cristobalite + pyrite + sulfur + jarosite, as the result of the base leaching by fluids concentrated in H2SO4 by atmospheric oxidation at the water table in a steam heated environment of H2S released by deeper boiling fluids. Another alteration zone in this area, called COP-2, is a fossil geothermal manifestation which shows characteristics of neutral to alkaline alteration represented mainly by the siliceous sinter superimposed over the acid alteration. The mineralogy and zoning of these alteration zones, and their relation with the hidrothermal solutions and the major structures of the area are analized.
Fracture Characterization in the Astor Pass Geothermal Field, Nevada
Walsh, D. C.; Reeves, D. M.; Pohll, G.; Lyles, B. F.; Cooper, C. A.
The Astor Pass geothermal field, near Pyramid Lake, NV, is under study as a site of potential geothermal energy production. Three wells have been completed in the graben of this typical Basin and Range geologic setting. Lithologies include a layer of unconsolidated sediment (basin fill) underlain by various tertiary volcanic units and granodiorite and metavolcanic basement rock. Characterization of fractures within the relatively impermeable rock matrix is being conducted for the three wells. Statistical analysis of fracture orientation, densities, and spacing obtained from borehole imaging logs is used to determine stress orientation and to generate a statistically equivalent Discrete Fracture Network (DFN) model. Fractures at depth are compared to fracture data collected in nearby outcrops of the same lithologic stratigraphy. Fracture geometry and density is correlated to mechanically discrete layers within the stratigraphy to test whether variations in fracturing can be attributed to variations in Young's modulus. Correlation of fracture geometry and densities with spinner flowmeter logs and distributed temperature sensor records are made in an effort to identify potential flowing fracture zones intersecting the borehole. Mean fracture aperture is obtained from open fracture counts and reservoir-scale transmissivity values (computed from a 30 day pump test) in the absence of readily available aperture data. The goal of this thorough fracture characterization is to create a physically relevant model which may be coupled with a multipurpose fluid flow and thermal simulator for investigation of geothermal reservoir behavior, particularly at the borehole scale.
A database for The Geysers geothermal field
Bodvarsson, G.S.; Cox, B.L.; Fuller, P.; Ripperda, M.; Tulinius, H.; Witherspoon, P.A.; Goldstein, N.; Flexser, S.; Pruess, K. (Lawrence Berkeley Lab., CA (USA)); Truesdell, A. (Geological Survey, Menlo Park, CA (USA))
In Fiscal Year 1985-1986 the Earth Sciences Division of Lawrence Berkeley Laboratory (LBL) began a multi-year project for SLC to organize and analyze the field data from The Geysers. In the first year, most of the work concentrated on the development of a comprehensive database for The Geysers, and conventional reservoir engineering analysis of the data. Essentially, all non-proprietary data for wells at The Geysers have been incorporated into the database, as well as proprietary data from wells located on State leases. In following years, a more detailed analysis of The Geysers data has been carried out. This report is a summary of the non- proprietary work performed in FY 1985--1986. It describes various aspects of the database and also includes: review sections on Field Development, Geology, Geophysics, Geochemistry and Reservoir Engineering. It should be emphasized that these background chapters were written in 1986, and therefore only summarize the information available at that time. The appendices contain individual plots of wellhead pressures, degree of superheat, steam flow rates, cumulative mass flows, injection rates and cumulative injection through 1988 for approximately 250 wells. All of the data contained in this report are non-proprietary, from State and non-State leases. The production/injection and heat flow data from the wells were obtained from the California State Division of Oil and gas (DOG) (courtesy of Dick Thomas). Most of the other data were obtained from SLC files in Sacramento (courtesy of Charles Priddy), or DOG files in Santa Rosa (courtesy of Ken Stelling). 159 refs., 23 figs., 3 tabs.
Seismicity and coupled deformation modeling at the Coso Geothermal Field
Kaven, J. O.; Hickman, S. H.; Davatzes, N. C.
Micro-seismicity in geothermal reservoirs, in particular in enhanced geothermal systems (EGS), is a beneficial byproduct of injection and production, as it can indicate the generation of high-permeability pathways on either pre-existing or newly generated faults and fractures. The hazard of inducing an earthquake large enough to be felt at the surface, however, is not easily avoided and has led to termination of some EGS projects. To explore the physical processes leading to permeability creation and maintenance in geothermal systems and the physics of induced earthquakes , we investigated the evolution of seismicity and the factors controlling the migration, moment release rate, and timing of seismicity in the Coso Geothermal Field (CGF). We report on seismicity in the CGF that has been relocated with high precision double-difference relocation techniques and simultaneous velocity inversions to understand hydrologic reservoir compartmentalization and the nature of subsurface boundaries to fluid flow. We find that two distinct compartments are present within the CGF, which are divided by an aseismic gap showing a relatively low Vp/Vs ratio, likely indicating lower temperatures or lower pore pressures within the gap than in the adjacent reservoir compartments. Well-located events with Mw> 3.5 tend to map onto reactivated fault structures that were revealed when imaged by the relocated micro-seismicity. We relate the temporal and spatial migration of moment release rate to the injection and production histories in the reservoir by employing a thermo-poro-elastic finite element model that takes into account the compartment boundaries defined by the seismicity. We find that pore pressure effects alone are not responsible for the migration of seismicity and that poro-elastic and thermo-elastic stress changes are needed in addition to fluid pressure effects to account for the observed moment release rates.
Development of a geothermal resource in a fractured volcanic formation: Case study of the Sumikawa Geothermal Field, Japan
Garg, S.K.; Pritchett, J.W.; Stevens, J.L.; Luu, L. [Maxwell Federal Div., Inc., San Diego, CA (United States); Combs, J. [Geo-Hills Associates, Los Altos, CA (United States)
The principal purpose of this case study of the Sumikawa Geothermal Field is to document and to evaluate the use of drilling logs, surface and downhole geophysical measurements, chemical analyses, and pressure transient data for the assessment of a high temperature volcanic geothermal field. The work accomplished during Year 1 of this ongoing program is described in the present report. A brief overview of the Sumikawa Geothermal Field is given. The drilling information and downhole pressure, temperature, and spinner surveys are used to determine feedzone locations, pressures and temperatures. Available injection and production data from both slim holes and large-diameter wells are analyzed to evaluate injectivity/productivity indices and to investigate the variation of discharge rate with borehole diameter. Finally, plans for future work are outlined.
Shear velocity of the Rotokawa geothermal field using ambient noise
Civilini, F.; Savage, M. K.; Townend, J.
Ambient noise correlation is an increasingly popular seismological technique that uses the ambient seismic noise recorded at two stations to construct an empirical Green's function. Applications of this technique include determining shear velocity structure and attenuation. An advantage of ambient noise is that it does not rely on external sources of seismic energy such as local or teleseismic earthquakes. This method has been used in the geothermal industry to determine the depths at which magmatic processes occur, to distinguish between production and non-production areas, and to observe seismic velocity perturbations associated with fluid extraction. We will present a velocity model for the Rotokawa geothermal field near Taupo, New Zealand, produced from ambient noise cross correlations. Production at Rotokawa is based on the "Rotokawa A" combined cycle power station established in 1997 and the "Nga Awa Purua" triple flash power plant established in 2010. Rotokawa Joint Venture, a partnership between Mighty River Power and Tauhara North No. 2 Trust currently operates 174 MW of generation at Rotokawa. An array of short period seismometers was installed in 2008 and occupies an area of roughly 5 square kilometers around the site. Although both cultural and natural noise sources are recorded at the stations, the instrument separation distance provides a unique challenge for analyzing cross correlations produced by both signal types. The inter-station spacing is on the order of a few kilometers, so waves from cultural sources generally are not coherent from one station to the other, while the wavelength produced by natural noise is greater than the station separation. Velocity models produced from these two source types will be compared to known geological models of the site. Depending on the amount of data needed to adequately construct cross-correlations, a time-dependent model of velocity will be established and compared with geothermal production processes.
Isotopic evaluation of the Afyon-Cobanlar-Heybeli geothermal field
The Cobanlar (Heybeli) geothermal field is located on the Afyon - Konya highway. Nine geothermal wells, belonging to Cobanlar and Bolvadin Municipalities, as well as complexes of thermal tourism of the Bolvadin Municipality are present in the site. Temperatures vary between 41 - 56.3 degreesin the wells which have depths between 60 - 263 m. The geothermal springs discharge at temperatures of 30 - 51degrees. Stratigraphically, Paleozoic aged basement rocks consisting of fillite - muskovite, kuvars - schists and marbles are overlain by Cenozoic aged continental sediments and Quaterniary aged slope deposits and alluviums. Dominant tectonical strike is NE - SW and NW - SE. According to the wells drilled in the region, the Karahasan Karbonates, expressed by crystallized limestones and marbles, seem to be the production zone for the goethermal fluid. This unit also signifies the reservoir. The Cenozoic aged sediments behave as the cap rock of the reservoir. The limestones of these continental sediments discharge groundwater to the wells drilled in the area. The volcanics, located in the area, are thought to be the probable heater of the geothermal system. Shallow groundwater mainly shows a plain - ward flow. The hydraulic gradient of the flow rate is at an average of 0.75 and 0.002 in high and slow slopes respectively. Rainfalls on the karstic area of Kurucuoba village, karstic structures and fracture zones of the Sultandag and Kizildag, form the principle recharge element of the shallow groundwaters. The Yesilcay Thermal presents Na - K - CO3 - HCO3 type water, while the J-04 well presents a Ca - Mg - CO3 - HCO3 type water. According to the Schoeller diagramme, the Yesilcay spring shows Na+K dominancy, while as other springs show Ca enrichment. Even though the springs recharge from similar areas, the hydrochemical evaluation has shown different circulations from varying lithologies. Most of the stable isotopes are located over the GML (Global Meteoric Line). Evaluation
Geothermal injection treatment: process chemistry, field experiences, and design options
Kindle, C.H.; Mercer, B.W.; Elmore, R.P.; Blair, S.C.; Myers, D.A.
The successful development of geothermal reservoirs to generate electric power will require the injection disposal of approximately 700,000 gal/h (2.6 x 10/sup 6/ 1/h) of heat-depleted brine for every 50,000 kW of generating capacity. To maintain injectability, the spent brine must be compatible with the receiving formation. The factors that influence this brine/formation compatibility and tests to quantify them are discussed in this report. Some form of treatment will be necessary prior to injection for most situations; the process chemistry involved to avoid and/or accelerate the formation of precipitate particles is also discussed. The treatment processes, either avoidance or controlled precipitation approaches, are described in terms of their principles and demonstrated applications in the geothermal field and, when such experience is limited, in other industrial use. Monitoring techniques for tracking particulate growth, the effect of process parameters on corrosion and well injectability are presented. Examples of brine injection, preinjection treatment, and recovery from injectivity loss are examined and related to the aspects listed above.
The Impact of Injection on Seismicity at The Geyses, California Geothermal Field
Majer, Ernest L.; Peterson, John E.
Water injection into geothermal systems has often become a required strategy to extended and sustain production of geothermal resources. To reduce a trend of declining pressures and increasing non-condensable gas concentrations in steam produced from The Geysers, operators have been injecting steam condensate, local rain and stream waters, and most recently treated wastewater piped to the field from neighboring communities. If geothermal energy is to provide a significant increase in ene...
Results of investigation at the Ahuachapan Geothermal Field, El Salvador
Fink, J.B. (HydroGeophysics, Tucson, AZ (United States))
The Ahuachapan Geothermal Field (AGF) is a 95 megawatt geothemal-sourced power-plant operated by the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) of El Salvador. During the past decade, as part of an effort to increase in situ thermal reserves in order to realize the full generation capacity of the AGF, extensive surface geophysical coverage has been obtained over the AGF and the prospective Chipilapa area to the east. The geophysical surveys were performed to determine physical property characteristics of the known reservoir and then to search for similar characteristics in the Chipilapa area. A secondary objective was to evaluate the surface recharge area in the highlands to the south of the AGF. The principal surface electrical geophysical methods used during this period were DC resistivity and magnetotellurics. Three available data sets have been reinterpreted using drillhole control to help form geophysical models of the area. The geophysical models are compared with the geologic interpretations.
A reservoir engineering assessment of the San Jacinto-Tizate Geothermal Field, Nicaragua
Ostapenko, S.; Spektor, S.; Davila, H.; Porras, E.; Perez, M.
More than twenty yews have passed since geothermal research and drilling took place at the geothermal fields in Nicaragua- Tbe well horn Momotombo Geothermal Field (70 We) has been generating electricity since 1983, and now a new geothermal field is under exploration. the San Jacinto-Tizate. Two reservoirs hydraulic connected were found. The shallow reservoir (270°C) at the depth of 550 - 1200 meters, and the deep one at > 1600 meters. Both of theme are water dominated reservoirs, although a two phase condition exist in the upper part of the shallow one. Different transient tests and a multi-well interference test have been carried out, very high transmissivity value were estimated around the well SJ-4 and average values for the others. A preliminar conceptual model of the geothermal system is given in this paper, as the result of the geology, geophysics, hydrology studies, drilling and reservoir evaluation.
The Ahuachapan geothermal field, El Salvador: Reservoir analysis
Aunzo, Z.; Bodvarsson, G.S.; Laky, C.; Lippmann, M.J.; Steingrimsson, B.; Truesdell, A.H.; Witherspoon, P.A. (Lawrence Berkeley Lab., CA (USA); Icelandic National Energy Authority, Reykjavik (Iceland); Geological Survey, Menlo Park, CA (USA); Lawrence Berkeley Lab., CA (USA))
The Earth Sciences Division of Lawrence Berkeley Laboratory (LBL) is conducting a reservoir evaluation study of the Ahuachapan geothermal field in El Salvador. This work is being performed in cooperation with the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) and the Los Alamos National Laboratory (LANL). This report describes the work done during the first year of the study (FY 1988--89), and includes the (1) development of geological and conceptual models of the field, (2) evaluation of the initial thermodynamic and chemical conditions and their changes during exploitation, (3) evaluation of interference test data and the observed reservoir pressure decline, and (4) the development of a natural state model for the field. The geological model of the field indicates that there are seven (7) major and five (5) minor faults that control the fluid movement in the Ahuachapan area. Some of the faults act as a barrier to flow as indicated by large temperature declines towards the north and west. Other faults act as preferential pathways to flow. The Ahuachapan Andesites provide good horizontal permeability to flow and provide most of the fluids to the wells. The underlying Older Agglomerates also contribute to well production, but considerably less than the Andesites. 84 refs.
Modeling study of the Pauzhetsky geothermal field, Kamchatka, Russia
Kiryukhin, A.V. [Institute of Volcanology, Kamchatsky (Russian Federation); Yampolsky, V.A. [Kamchatskburgeotermia State Enterprise, Elizovo (Russian Federation)
Exploitation of the Pauzhetsky geothermal field started in 1966 with a 5 MW{sub e} power plant. A hydrogeological model of the Pauzhetsky field has been developed based on an integrated analysis of data on lithological units, temperature, pressure, production zones and natural discharge distributions. A one-layer 'well by well' model with specified vertical heat and mass exchange conditions has been used to represent the main features of the production reservoir. Numerical model development was based on the TOUGH2 code [Pruess, 1991. TOUGH2 - A General Purpose Numerical Simulator for Multiphase Fluid and Heat Flow, Lawrence Berkeley National Laboratory Report, Berkeley, CA; Pruess et al., 1999. TOUGH2 User's Guide, Version 2.0, Report LBNL-43134, Lawrence Berkeley National Laboratory, Berkeley, CA] coupled with tables generated by the HOLA wellbore simulator [Aunzo et al., 1991. Wellbore Models GWELL, GWNACL, and HOLA, Users Guide, Draft, 81 pp.]. Lahey Fortran-90 compiler and computer graphical packages (Didger-3, Surfer-8, Grapher-3) were also used to model the development process. The modeling study of the natural-state conditions was targeted on a temperature distribution match to estimate the natural high-temperature upflow parameters: the mass flow-rate was estimated at 220 kg/s with enthalpy of 830-920 kJ/kg. The modeling study for the 1964-2000 exploitation period of the Pauzhetsky geothermal field was targeted at matching the transient reservoir pressure and flowing enthalpies of the production wells. The modeling study of exploitation confirmed that 'double porosity' in the reservoir, with a 10-20% active volume of 'fractures', and a thermo-mechanical response to reinjection (including changes in porosity due to compressibility and expansivity), were the key parameters of the model. The calibrated model of the Pauzhetsky geothermal field was used to forecast reservoir behavior under different exploitation scenarios for
A general overview of geothermal energy is given that includes a short description of the active and stable areas in the world. The possibilities of geothermal development in Argentina are analyzed taking into account the geothermal fields of the country. The environmental benefits of geothermal energy are outlined
Basin filling related to the Philippine Sea Plate motion in Beppu Bay, southwest Japan
Yamada, Keitaro; Takemura, Keiji; Kuwae, Michinobu; Ikehara, Ken; Yamamoto, Masanobu
Strike-slip basins are one of the most important accumulation spaces for sediment of terrigenous, biogenic, and volcanic origins, and generally include large amount of event deposits. Although these event deposits are important basin filling process, research on this topic, particularly the effects of event deposits, is insufficient. In this study, we discuss sedimentation features based on grain composition and other properties for ca. 3000 year periods in Beppu Bay, which is strike-slip basin located at the western end of an arc-bisecting dextral fault known as Median Tectonic Line (MTL) associated with the northwestward subduction of the Philippine Sea Plate. This sediment is composed of hemipelagic clay and coarser event layers of turbidites referred to as types A, B, and C; ash layers referred to as type D; and other referred to as type E. The turbidite event layers, which accounted for 92% of the total major event layer, with >1 cm thickness, consist of particles related to volcanism, including hydrothermal activity. The events control the regional filling rate and transportation of coarse and heavy volcaniclastic materials. In particular, type A, which accounted for 73% of the total major event layer thickness, is likely induced by earthquakes related to the MTL, according to its age. As a result, the basin filling processes are controlled mainly by tectonics related to the subduction of the Philippine Sea Plate.
Innovative approach for risk assessment in green field geothermal project
Batini, F.; Wees, J.-D. van
At present, the worldwide geothermal energy production provides less than 1% of the world's energy needs but the geothermal resources confined in the first 6 km of the earth's crust are estimated to be in the fairly above 200 GW of which 50-80 GW are located in Europe. Exploring and developing at la
3D Magnetotelluic characterization of the Coso GeothermalField
Newman, Gregory A.; Hoversten, G. Michael; Wannamaker, Philip E.; Gasperikova, Erika
Electrical resistivity may contribute to progress inunderstanding geothermal systems by imaging the geometry, bounds andcontrolling structures in existing production, and thereby perhapssuggesting new areas for field expansion. To these ends, a dense grid ofmagnetotelluric (MT) stations plus a single line of contiguous bipolearray profiling has been acquired over the east flank of the Cosogeothermal system. Acquiring good quality MT data in producing geothermalsystems is a challenge due to production related electromagnetic (EM)noise and, in the case of Coso, due to proximity of a regional DCintertie power transmission line. To achieve good results, a remotereference completely outside the influence of the dominant source of EMnoise must be established. Experimental results so far indicate thatemplacing a reference site in Amargosa Valley, NV, 65 miles from the DCintertie, isstill insufficient for noise cancellation much of the time.Even though the DC line EM fields are planar at this distance, theyremain coherent with the nonplanar fields in the Coso area hence remotereferencing produces incorrect responses. We have successfully unwrappedand applied MT times series from the permanent observatory at Parkfield,CA, and these appear adequate to suppress the interference of thecultural EM noise. The efficacy of this observatory is confirmed bycomparison to stations taken using an ultra-distant reference site eastof Socorro, NM. Operation of the latter reference was successful by usingfast ftp internet communication between Coso Junction and the New MexicoInstitute of Mining and Technology, using the University of Utah site asintermediary, and allowed referencing within a few hours of datadownloading at Coso. A grid of 102 MT stations was acquired over the Cosogeothermal area in 2003 and an additional 23 stations were acquired toaugment coverage in the southern flank of the first survey area in 2005.These data have been inverted to a fully three
Magnetostratigraphy of the Ahuachapan-Chipilapa geothermal field, El Salvador
Fucugauchi, Jaime Urrutia [Universidad Nacional Autonoma de Mexico, Lab. de Paleomagnetismo y Geofisica Nuclear, Coyoacan (Mexico); Rodriguez, Vicente Torres; Partida, Eduardo Gonzalez [Instituto de Investigaciones Electricas, Dept. de Geotermia, Cuernavaca, Morelos (Mexico)
The volcanic stratigraphy for the Ahuachapan-Chipilapa geothermal field is defined on the basis of the magnetostratigraphic results on 156 oriented samples from 33 sites. The magnetostratigraphic sequence shows that the major volcanism associated with the Concepcion de Ataco caldera and the Cuyanausul volcano took place during the middle Brunhes chron (Quaternary). Pre-caldera activity of small centers such as Empalizada and Apaneca in the southern sector of the field occurred during the early Brunhes (0.77{+-}0.07 Ma). Basaltic-andesitic activity associated with the Cuyanausul volcano took place earlier, i.e. during the Matuyama chron, possibly around 1.3{+-}0.15 and 1.7{+-}0.3 Ma. The local igneous basement is composed of Late Miocene-Pliocene andesites, ignimbrites and volcano-sedimentary deposits. Normal polarities and a K-Ar date of 7.37{+-}0.73 Ma indicate that the volcanic activity in the study area extends beyond the Gauss chron. The polarity of some of the units in the post-caldera sequence and in the Concepcion de Ataco and Cuyanausul sequences suggest that they may have recorded short polarity sub-chrons. (Author)
Heterogeneous surface displacement pattern at the Hatchobaru geothermal field inferred from SAR interferometry time-series
Ishitsuka, Kazuya; Tsuji, Takeshi; Matsuoka, Toshifumi; Nishijima, Jun; Fujimitsu, Yasuhiro
We estimated surface displacements using persistent scatterer SAR interferometry (PS-InSAR) around the Hatchobaru geothermal field, Japan, from 18 ALOS/PALSAR images acquired from July 2007 to December 2010. Generally, geothermal fields, covered with natural targets such as rocky terrain and vegetation, have been one of the difficult targets for PS-InSAR analysis. However, we applied space adaptive filtering to increase the number of pixels for measuring surface displacement. The results of our analysis demonstrate ground subsidence with decaying velocity over the observation period around the geothermal field. The spatial pattern of ground subsidence includes sharp boundaries of subsidence that can be interpreted as fault traces. We demonstrated the usefulness of PS-InSAR analysis with the space adaptive filtering to estimate surface displacements with high spatial resolution and high spatial density around a geothermal field.
Discovery and geology of the Desert Peak geothermal field: a case history. Bulletin 97
Benoit, W.R.; Hiner, J.E.; Forest, R.T.
A case history of the exploration, development (through 1980), and geology of the Desert Peak geothermal field is presented. Sections on geochemistry, geophysics, and temperature-gradient drilling are included.
An overview of the geochemistry of Cerro Prieto geothermal field with emphasis on isotopic changes
This paper reviews the global geochemical changes in the Cerro Prieto geothermal reservoir due to exploitation and presents some important conclusions. Distribution of oxygen-18, deuterium, chloride concentrations, enthalpy and geothermometry for the field are presented
Detection of Surface Temperature Anomalies in the Coso Geothermal Field Using Thermal Infrared Remote Sensing
Coolbaugh, M.; Eneva, M.; Bjornstad, S.; Combs, J.
We use thermal infrared (TIR) data from the spaceborne ASTER instrument to detect surface temperature anomalies in the Coso geothermal field in eastern California. The identification of such anomalies in a known geothermal area serves as an incentive to search for similar markers to areas of unknown geothermal potential. We carried out field measurements concurrently with the collection of ASTER images. The field data included reflectance, subsurface and surface temperatures, and radiosonde atmospheric profiles. We apply techniques specifically targeted to correct for thermal artifacts caused by topography, albedo, and thermal inertia. This approach has the potential to reduce data noise and to reveal thermal anomalies which are not distinguishable in the uncorrected imagery. The combination of remote sensing and field data can be used to evaluate the performance of TIR remote sensing as a cost-effective geothermal exploration tool.
Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula, Iceland
Keiding, Marie
We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992-1999 and 2003-2008 as well as GPS data from 2000-2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10. cm is observed during the first 2. years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction. © 2010 Elsevier B.V.
Mexican--American cooperative program at the Cerro Prieto Geothermal Field
Witherspoon, P.A.; Espinosa, H.A.; Lippmann, M.J.; Mercado, A.M.; Wollenberg, H.A.
The Cerro Prieto project incorporates studies of the geologic, hydrogeologic, geochemical, and geophysical setting of the geothermal field as well as its structural, reservoir engineering, and subsidence characteristics. A description of the activities involved in each part of this cooperative program is presented. Text of the agreement between the Comision Federal de Electricidad of Mexico and the USERDA for the cooperative study of the Cerro Prieto geothermal field is included.
Radon and ammonia transects across the Cerro Prieto geothermal field
Semprini, L.; Kruger, P.
Radon and ammonia transects, conducted at the Cerro Prieto geothermal field, involve measurement of concentration gradients at wells along lines of structural significance in the reservoir. Analysis of four transects showed radon concentrations ranging from 0.20 to 3.60 nCi/kg and ammonia concentrations from 17.6 to 59.3 mg/l. The data showed the lower concentrations in wells of lowest enthalpy fluid and the higher concentrations in wells of highest enthalpy fluid. Linear correlation analysis of the radon-enthalpy data indicated a strong relationship, with a marked influence by the two-phase conditions of the produced fluid. It appears that after phase separation in the reservoir, radon achieves radioactive equilibrium between fluid and rock, suggesting that the phase separation occurs well within the reservoir. A two-phase mixing model based on radon-enthalpy relations allows estimation of the fluid phase temperatures in the reservoir. Correlations of ammonia concentration with fluid enthalpy suggests an equilibrium partitioning model in which enrichment of ammonia correlates with higher enthalpy vapor.
Results of investigations at the Ahuachapan geothermal field, El Salvador
Dennis, B.; Goff, F.; Van Eeckhout, E.; Hanold, B. (comps.)
Well logging operations were performed in eight of the geothermal wells at Ahuachapan. High-temperature downhole instruments, including a temperature/rabbit, caliper, fluid velocity spinner/temperature/pressure (STP), and fluid sampler, were deployed in each well. The caliper tool was used primarily to determine if chemical deposits were present in well casings or liners and to investigate a suspected break in the casing in one well. STP logs were obtained from six of the eight wells at various flow rates ranging from 30 to 80 kg/s. A static STP log was also run with the wells shut-in to provide data to be used in the thermodynamic analysis of several production wells. The geochemical data obtained show a system configuration like that proposed by C. Laky and associates in 1989. Our data indicate recharge to the system from the volcanic highlands south of the field. Additionally, our data indicate encroachment of dilute fluids into deeper production zones because of overproduction. 17 refs., 50 figs., 10 tabs.
Modeling research in low-medium temperature geothermal field, Tianjin
WANG; Kun(王坤); LI; Chunhua(李春华)
The geothermal reservoir in Tianjin can be divided into two parts: the upper one is the porous medium reservoir in the Tertiary system; the lower one includes the basement reservoir in Lower Paleozoic and Middle-Upper Proterozoic. Hot springs are exposed in the northern mountain and confined geothermal water is imbedded in the southern plain. The geothermal reservoir is incised by several fractures. In recent years, TDS of the geothermal water have gone up along with the production rate increasing, along the eastern fracture zone (Cangdong Fracture and West Baitangkou Fracture). This means that the northern fracture system is the main seepage channel of the deep circulation geothermal water, and the reservoir has good connection in a certain area and definite direction. The isotopic research about hydrogen and carbon chronology indicates that the main recharge period of geothermal water is the Holocene Epoch, the pluvial and chilly period of 20 kaBP. The karst conduits in weathered carbonate rocks of the Proterozoic and Lower Paleozoic and the northeast regional fracture system are the main feeding channels of Tianjin geothermal water. Since the Holocene epoch, the geothermal water stayed at a sealed warm period. The tracer test in WR45 doublet system shows that the tracer test is a very effective measure for understanding the reservoir's transport nature and predicting the cooling time and transport velocity during the reinjection. 3-D numerical simulation shows that if the reinjection well keeps a suitable distance from the production well, reinjection will be a highly effective measure to extract more thermal energy from the rock matrix. The cooling of the production well will not be a problem.
Applications of stable isotopes and radioisotopes in the exploration and reservoir management of Philippine geothermal fields
The development of indigenous geothermal energy resources is currently one of the primary thrusts of the country's energy program. Presently, the Philippines has a total of geothermal generating capacity of about 1400 MWe. This comprises about 20% of the total energy mix and electricity requirements of the country. By 1998, an additional capacity of about 500 MWe will be commissioned, and the PHilippines would be generating 1900 MWe of electricity from geothermal energy resources. From 1990 to 1993, PNOC EDC (Philippine National Oil Company, Energy Development Corporation) has been granted a research contract by the International Atomic Energy Agency (IAEA). The Company has also been a recipient since 1991 of an IAEA Technical Assistance on the use of stable isotope techniques in geothermal hydrology. Stable isotopes, particularly 18O and 2H, in conjunction with other geochemical parameters and geological and geophysical data, have been used to: a) establish the local meteoric water line; b) determine the origin of geothermal fluids; c) delineate the elevation of recharge of geothermal and ground water systems; d) confirm pre-exploitation hydrochemical models; e) identify physical and chemical processes due to exploitation of the geothermal resource (i.e. reinjection fluid returns, incursion of cold meteoric water, boiling due to pressure drawdown and mixing with acidic steam condensates); and, f) estimate reservoir temperatures. Techniques using radioisotopes, such as 14C, have also been used for the age-dating of charred wood samples collected from some of our geothermal exploration areas. The detection of 3H has also been used as an indicator for the incursion of recent cold meteoric water into the geothermal system. Tracer studies using 131I, have also been previously carried out, in coordination with the Philippine Nuclear Research Institute, to determine local hydrology and flow paths of reinjected water in some of our geothermal fields
Züheyr KAMACI
Full Text Available Geothermal energy which is one of the reuseable energy resources, can save as much as 77 million barrels of petroleum equivalent annually when used in the production of electricity and heating-environment. Geophysical exploration methods plays in important role in the fields of geothermal exploration, development and observational studies. Thermal and geoelectrical methods are the most effective methods which shows the temperature variation anomalies and mechanical drilling places. But, when the other methods of gravity, magnetic, radiometric, well geophysics and well logs can be used in conjunction with seismic tomography, apart from the mentioned geophysical exploration method, better results could be obtained. From the above mentioned facts various case history reports are given from our country and worldwide to determine geothermal energy resources by using geophysical exploration technique application. From these results of studies a 55 °C hot water artessian aquifer is found in the Uşak-Banaz geothermal field by applying geoelectrical methods.
Overview of the Wayang Windu geothermal field, West Java, Indonesia
Bogie, Ian [Sinclair, Knight Merz Ltd., PO Box 9806, Newmarket, Auckland (New Zealand); Kusumah, Yudi Indra; Wisnandary, Merry C. [Magma Nusantara Ltd., Wisma Mulia 50th Floor, Jl. Jend. Gatot Subroto no. 42, Jakarta 12710 (Indonesia)
The Wayang Windu geothermal field, West Java, Indonesia, is interpreted to be transitional between vapour-dominated and liquid-dominated conditions with four coalesced fluid upwelling centres that generally become younger and more liquid-dominated towards the south. Two of these centres are associated with the large Gunung Malabar andesite stratovolcano and the other two with the smaller aligned Gunung Wayang and Gunung Windu andesitic volcanoes to the south. The overall potential resource area is of the order of 40 km{sup 2}. Deep wells encounter a deep liquid reservoir whose top, which ranges from 0 to 400 m above sea level (m asl) becomes progressively deeper toward the south. As pressure versus elevation conditions are the same throughout the deep liquid reservoir it is likely to be contiguous. This liquid-dominated reservoir is overlain by three separate vapour-dominated reservoirs. The northernmost is the largest as it is coalesced over two separate fluid upwelling centres. Its low gas content, size, prolonged productivity and isobaric for elevation nature, preclude it from being a parasitic steam zone. Mineralogical relationships demonstrate that this vapour zone was originally liquid-dominated with a deep water level as high as 1700 m asl. Subsequent boil off may reflect low recharge rates due to hydrological isolation at depth. To the south, the vapour-dominated reservoirs decrease in thickness and are characterized by progressively higher pressures, temperatures and gas contents. These changes suggest that the southernmost vapour-dominated zone is the youngest and that these zones become increasing older to the north. (author)
The Momotombo Geothermal Field, Nicaragua: Exploration and development case history study
This case history discusses the exploration methods used at the Momotombo Geothermal Field in western Nicaragua, and evaluates their contributions to the development of the geothermal field models. Subsequent reservoir engineering has not been synthesized or evaluated. A geothermal exploration program was started in Nicaragua in 1966 to discover and delineate potential geothermal reservoirs in western Nicaragua. Exploration began at the Momotombo field in 1970 using geological, geochemical, and geophysical methods. A regional study of thermal manifestations was undertaken and the area on the southern flank of Volcan Momotombo was chosen for more detailed investigation. Subsequent exploration by various consultants produced a number of geotechnical reports on the geology, geophysics, and geochemistry of the field as well as describing production well drilling. Geological investigations at Momotombo included photogeology, field mapping, binocular microscope examination of cuttings, and drillhole correlations. Among the geophysical techniques used to investigate the field sub-structure were: Schlumberger and electromagnetic soundings, dipole mapping and audio-magnetotelluric surveys, gravity and magnetic measurements, frequency domain soundings, self-potential surveys, and subsurface temperature determinations. The geochemical program analyzed the thermal fluids of the surface and in the wells. This report presents the description and results of exploration methods used during the investigative stages of the Momotombo Geothermal Field. A conceptual model of the geothermal field was drawn from the information available at each exploration phase. The exploration methods have been evaluated with respect to their contributions to the understanding of the field and their utilization in planning further development. Our principal finding is that data developed at each stage were not sufficiently integrated to guide further work at the field, causing inefficient use of
Radon-222 behavior at the Latera geothermal field (Northern Latium)
Permanent probes to sample soil gases were placed at the Latera geothermal area, Vulsini Mts. (Latium, Italy). Due to the remarkable uranium and thorium concentrations in the alkali-potassic volcanites outcropping in the area, quite high Rn-222 values, ranging from 740 up to 11.640 pCi/L, were found. This area results as one of the most anomalous in Italy. The highest radon activities match geological and tectonic structures, such as fractures and faults, and a deep high structure, which constitutes the geothermal reservoir. These high radon values also conform to a major amount of helium-4 and carbon dioxide. The latter gases are enriched in the gaseous phase of the geothermal fluids, and their migration is also controlled by structural features. All this suggests that the enrichment of radon-222 in the soil gases sampled in connection with the geothermal reservoir can be linked to a direct contribution of radium-226 carried by deep seated fluids from the reservoir itself
Structural Mapping of Olkaria Domes Geothermal Field using Geochemical Soil Gas Surveys, Remote Sensing and GIS
Munyiri, Samuel Kinyua, 1983-
Olkaria Geothermal field is a high temperature geothermal system located on the eastern arm of the East African Rift System. It is placed within the Central Kenya Rift Valley and is dominated by late Quaternary rhyolitic volcanism. Basalts, tuffs and trachytes occupy the subsurface with the latter forming the reservoir rock. Normal faulting mapped during this study is prominent in the Domes field with dips ranging from 20° to 80° to the west and the east. Fault strikes vary from north-south, ...
Slope stability analysis of landslide in Wayang Windu Geothermal Field, Pangalengan, West Java Province, Indonesia
Yuhendar, A. H.; Wusqa, U.; Kartiko, R. D.; Raya, N. R.; Misbahudin
Large-scale landslide occurred in Margamukti village, Pangalengan, Bandung Regency, West Java Province, Indonesia. The landslide damaged geothermal gas pipeline along 300 m in Wayang Windu Geothermal Field. Based on field observation, landslide occured in rotational sliding movement. Laboratory analysis were conducted to obtain the characteristics of the soil. Based on the condition of the landslide in this area, the Factor of Safety can be simulated by the soil mechanics approach. Factor of safety analysis based on soil cohesion and internal friction angle was conducted using manual sensitivity analysis for back analysis. The analysis resulted soil cohesion in critical condition (FSgranular media.
Geothermal structure in the Hatchobaru geothermal field derived from detailed gravity and resistivity structure; Seimitsu juryoku oyobi hiteiko kozo kara mita haccho genchi chinetsu chitai no chinetsu kozo
Tagomori, K.; Honda, M.; Akiyoshi, M.; Nagano, H.; Haruguchi, K. [Kyushu Electric Power Co., Inc., Fukuoka (Japan)] Ushijima, K. [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering
Faults in the Hatchobaru geothermal field, Ohita Prefecture have been identified or presumed by various surface explorations and surveys and also verified by drilling. In this field, there is the Ohtake geothermal plant (12.5 MW) of Kyushu Electric Power Co. and in the early stage of the development, relatively detailed gravity structures were surveyed within the range of about 20km {sup 2} including the above field and this range embraces the existing production wells and reduction wells as well as their surroundings. However, any elucidation of the geothermal structure deeper than the development level remains insufficient. The elucidation of the deeper structure and the geothermal structure in its surroundings, which are necessary for determination of the drilling point for a replenishing well to be drilled in the future, is now an important issue. In this article, are put together the results of studies on the feature of the geothermal structure of the zone as well as the possibility of geothermal development of the depth based on the density structure and resistivity structure obtained from the gravity exploration and electromagnetic method exploration executed in recent years in the Hatchobaru field taken into consideration the latest available data. The gravity exploration is effective for a general survey of a wide area, but it has been found in Hatchobaru that the method is also effective for a precision survey once its observation stations are set thickly. 11 refs., 14 figs.
Chemical Variations in the Rocks of La Primavera Geothermal Field (Mexico) Related with Hydrothermal Alteration
Prol-Ledesma, R.M.; Hernandez-Lombardini, S.I.; Lozano-Santa Cruz, R.
The origin and fate of the components dissolved in the geothermal fluids are of great importance in the study of epithermal deposits, and in the environmental considerations for exploitation of geothermal fields. The chemical study of La Primavera geothermal field in Mexico has environmental importance due to the high arsenic concentration observed in the thermal water and the possible contamination of aquifers in the area. The variations in the chemistry of all altered samples with respect to unaltered samples indicates depletion of manganese, and the alkalis; and enrichment in iron and magnesium. Most samples show an enrichment in aluminum and titanium, and depletion in silica and calcium. Trace elements follow different trends at various depths: shallow depths are more favorable for deposition of the analyzed trace elements than the surface or the deep part of the reservoir.
Uranium-thorium series radionuclides in brines and reservoir rocks from two deep geothermal boreholes in the Salton Sea geothermal field, southeastern California
Naturally occurring U and Th series radionuclides have been analyzed in high temperature brines (∼ 300 degree C, 25 wt% dissolved solids) and associated rocks from two deep geothermal wells located on the northeastern margin of the Salton Sea Geothermal Field (SSGF). These data are part of a study of the SSGF as a natural analog of possible radionuclide behavior near a nuclear waste repository constructed in salt beds, and permit evaluation of some characteristics of water-rock interaction in the SSGF
The microseismic observation in dry steam type geothermal field in Indonesia
Isroi, Alamsyah Rizki; Singarimbun, Alamta
In this paper, we discuss about the use of micro earthquake method in monitoring of dry steam type geothermal field in Indonesia. This study takes X geothermal field, which is the pioneer of Indonesia's geothermal development. Therefore, it should be maintained for long period by doing proper production and reinjection activities. Hypocenters of microseismic events is represented movements of reinjection fluids that means it could be space where fractured zone is formed. We use Single Event Determination (SED) method to relocate the hypocenters of microseismic event during the period of January - June 2014. About 179 events of micro earthquake were recorded on that period, these micro earthquake have magnitudes in range of 0.4 to 2.1 SR. Some of them are related to reinjection fluid from injection well INJ21. The hypocenters which is related to injection fluid from INJ21 shows that fractured zones exist on there. These fractured zones is located in geothermal reservoirs based on the geological setting. Fractured zones caused by high pressure of reinjection fluid where it happens in geothermal reservoirs containing high temperature, when reinjection water contacted with high temperature reservoir, it will be a new fractured zones because of high intensity of micro earthquake events.
Fundamental investigations in the field of the geothermal power engineering
Paper presents the results of the many-year fundamental studies dealing with investigation into properties of a geothermal coolant, with problems of hydro-gas dynamics and erosion-and-corrosion effect on multicomponent media metals. Paper presents the results of the experimental investigations into crises in the upper boundary curve, dispersed structure of two-phase flows, film-formation and flow of liquid films and moisture separation, sedimentation, physical and chemical processes of erosion and corrosion and of stress corrosion cracking of metal
Prospects of development of highly mineralized high-temperature resources of the Tarumovskoye geothermal field
Alkhasov, A. B.; Alkhasova, D. A.; Ramazanov, A. Sh.; Kasparova, M. A.
The promising nature of integrated processing of high-temperature geothermal brines of the Tarumovskoye geothermal field is shown. Thermal energy of a geothermal brine can be converted to the electric power at a binary geothermal power plant (GPP) based on low-boiling working substance. The thermodynamic Rankine cycles are considered which are implemented in the GPP secondary loop at different evaporation temperatures of the working substance―isobutane. Among them, the most efficient cycle from the standpoint of attaining a maximum power is the supercritical one which is close to the so-called triangular cycle with an evaporation pressure of p e = 5.0 MPa. The used low-temperature brine is supplied from the GPP to a chemical plant, where main chemical components (lithium carbonate, burnt magnesia, calcium carbonate, and sodium chloride) are extracted from it according to the developed technology of comprehensive utilization of geothermal brines of chloride-sodium type. The waste water is delivered to the geotechnological complex and other consumers. For producing valuable inorganic materials, the electric power generated at the GPP is used. Owing to this, the total self-sufficiency of production and independence from external conditions is achieved. The advantages of the proposed geotechnological complex are the full utilization of the heat potential and the extraction of main chemical components of multiparameter geothermal resources. In this case, there is no need for reverse pumping, which eliminates the significant capital costs for building injection wells and a pumping station and the operating costs for their service. A characteristic of the modern state of the field and estimated figures of the integrated processing of high-temperature brines of well no. 6 are given, from which it follows that the proposed technology has a high efficiency. The comprehensive development of the field resources will make it possible to improve the economic structure of the
Monitoring the movement of the cooler fluids in the deep geothermal reservoirs of Greater Tongonan geothermal field, Philippines
Two types of cooler fluids are present in the Greater Tongonan geothermal field, namely the reinjected waste brine in the Tongonan reservoir and the shallow groundwater in the Mahanagdong reservoir. The influx of reinjection fluids in the production area of Tongonan became apparent in 1990 after seven years of commercial operations of the first power plant. The wells that previously delivered highly two-phase fluids started to become liquid-saturated. As a consequence, the fluid temperatures dropped by 10 deg. C and the field enthalpy declined from 2,200 kJ/kg to 1,600 kJ/kg. The new distribution of stable isotopes shows isotopic enrichment in the western part of the field [+1.00 per mille δ18O] where waste brine injection takes place. In Mahanagdong, the field started to generate 180 MW of power in July 1997 that brought about changes to the physical and chemical characteristics of the reservoir. After about one year of commercial operation, the production sector closest to the western part of the field sustained decline in fluid temperature and salinity ultimately leading to decline in bore output. The present stable isotope distribution across the field illustrates invasion of isotopically depleted fluids from the west to the production part of the field, passing through a northwest-trending structure. (author)
3-D inversion of magnetotelluric data in the Kakkonda geothermal field, northern Japan
Uchida, T.; Lee, T. J.; Červ, Václav
Tokyo : SEGJ, 2003, s. 274-280. [SEGJ international symposium /6./. Tokyo (JP), 22.01.2003-24.01.2003] R&D Projects: GA MŠk ME 185 Institutional research plan: CEZ:AV0Z3012916 Keywords : magnetotelluric method * 3-D interpretation * geothermal field Subject RIV: DE - Earth Magnetism, Geodesy, Geography
French know-how in the field of geothermal energy. District heating and electricity generation systems
This brochure is aimed at presenting the French expertise, public and private, at international level in the field of geothermal energy (district heating and electricity generation systems). It presents a summary of the French public policy framework, measures to support Research and Development, innovation and training and offers from private companies. It has been designed by the ADEME in cooperation with the French ministry for Ecology and Sustainable Development, the French association of geothermal energy professionals, Ubifrance (the French Agency for international business development) and the French renewable energies union
222Rn behavior at the latera geothermal field (Northern Latium, Italy)
Permanent probes to sample soil gases were placed at the Latera geothermal field, located in the Volsini Mts., Latium, Italy. Due to high uranium concentrations in the area's alkali-potassic volcanics outcropping, quite high 222Rn values, ranging from 9,260 up to 753,000 Bq/m3, were found. The highest radon activities match tectonic structures such as fractures and faults, and a deep high structure which consitutes the geothermal reservoir. These high radon values also conform to a major amount of 4He and CO2. The latter gases are enriched in the gaseous phase of the geothermal fluids, and their migration is also controlled by structural features. This suggests that the enrichment of 222Rn in the soil gases, can be linked to a direct contribution of 226Ra, carried by deep-seated fluids from the reservoir itself. (author) 17 refs.; 5 figs.; 1 tab
The possibilities of utilisation of heat from Tattapani Geothermal field, India
Sarolkar, P.B. [Geological Survey of India, Hyderabad (India); Pitale, U.L. [Geological Survey of India, Nagpur (India)
The Tattapani Geothermal field produces + 1800 1pm thermal water of 100{degrees}C from five production wells. The hot water production can sustain electricity production of 300 kWe by using a binary cycle power plant. The heat energy of effluent water from power plant can be utilized for direct heat utilization on horticulture, aquaculture, cold storage, silviculture etc; to augment the economics of the power plant be spot can be developed as a centre for tourist attraction by constructing botanical park, greenhouse, geyser show and crocodile farm. The direct heat utilization shemes can be planned in cascading order to achieve maximum utility of thermal water. Additional deep drilling is essential for optimum commercial utilization of the Geothermal energy. The direct heat utilisation shemes along with binary cycle power plant may help in development of the geothermal energy and boosting the economy of this region.
3-D analysis and interpretation of magnetotelluric data from the Aluto-Langano geothermal field, Ethiopia
Samrock, F.; Kuvshinov, A.; Bakker, J.; Jackson, A.; Fisseha, S.
The Main Ethiopian Rift Valley encompasses a number of volcanoes, which are known to be actively deforming with reoccurring periods of uplift and setting. One of the regions where temporal changes take place is the Aluto volcanic complex. It hosts a productive geothermal field and the only currently operating geothermal power plant of Ethiopia. We carried out magnetotelluric (MT) measurements in early 2012 in order to identify the source of unrest. Broad-band MT data (0.001-1000 s) have been acquired at 46 sites covering the expanse of the Aluto volcanic complex with an average site spacing of 1 km. Based on this MT data it is possible to map the bulk electrical resistivity of the subsurface down to depths of several kilometres. Resistivity is a crucial geophysical parameter in geothermal exploration as hydrothermal and magmatic reservoirs are typically related to low resistive zones, which can be easily sensed by MT. Thus by mapping the electrical conductivity one can identify and analyse geothermal systems with respect to their temperature, extent and potential for production of energy. 3-D inversions of the observed MT data from Aluto reveal the typical electrical conductivity distribution of a high-enthalpy geothermal system, which is mainly governed by the hydrothermal alteration mineralogy. The recovered 3-D conductivity models provide no evidence for an active deep magmatic system under Aluto. Forward modelling of the tippers rather suggest that occurrence of melt is predominantly at lower crustal depths along an off-axis fault zone a few tens of kilometres west of the central rift axis. The absence of an active magmatic system implies that the deforming source is most likely situated within the shallow hydrothermal system of the Aluto-Langano geothermal field.
Hydrochemical modelling and determination of 14C ages of geothermal waters in Kizildere and Tekkehamam fields
Many geothermal fluids are encountered as springs and wells in the area between Buharkent - Yenice - Pamukkale located in the Aegean Region to the east of the Bueyuek Menderes Graben. This study, constituting a part of the project called 'Age and Origin Determination of the High Temperature Geothermal Fluids in the Bueyuek Menderes Graben' and directed by the MTA General Directorate, aims the recharge and circulation period verification of related resources by means of interpreting isotopic and hydrochemical data of the above mentioned region. For this purpose, water chemistry, δ18O, δ2H, δ3H, 14C, δ34S-SO4 ve δ18O-SO4 isotope sampling have been realized in order to determine the geochemical processes taken place in underground. As a result of the study the origin, the recharge altitudes and the circulation periods of grouped fluids with temperatures between 35 degrees- 242 degreeslocated in the region were clarified. According to the given chemical data, hydrochemically characterized waters are classified in 10 different types. It has been indicated that, six subtypes of the classification are constituted from the mixtures of waters at 242 degreesand 4th type Na-HCO3 belonging to Kizildere thermal waters, first type Ca-HCO3 waters, second type Ca-HCO3-SO4 waters and third type Ca-SO4 waters. According to the evaluation of the 14C isotope, the geothermal fluid discharging from the Kizildere Power Plant, corresponds to a turnovertime of 22.500 - 27.500 years. Previous studies reveal that the waters of the Tekkehamam geothermal field originate from the mixture of shallow groundwaters encountered in the site with geothermal fluids underflowing from the Kizildere geothermal field, in north-south direction. Taken into consideration this mentioned mixture model, the 14C isotope indicates a turnovertime of 31.000 years for R-1 geothermal well and 35.000 years for the нnatlм spring, located in the Tekkehamam geothermal field
Impacts of geothermal energy developments on hydrological environment in hot spring areas
Taniguchi, M.
Water-energy nexus such as geothermal energy developments and its impacts on groundwater, river water, and coastal water is one of the key issues for the sustainable society. This is because the demand of both water and energy resources will be increasing in near future, and the tradeoff between both resources and conflict between stakeholders will be arisen. Geothermal power generation, hot springs heat power generation, and steam power generation, are developing in hot spring areas in Ring of Fire countries including Japan, as renewable and sustainable energy. Impacts of the wasted hot water after using hot springs heat and steam power generation on ecosystem in the rivers have been observed in Beppu, Oita prefecture, Japan. The number of the fish species with wasted hot water in the Hirata river is much less than that without wasted hot water in Hiyakawa river although the dominant species of tilapia was found in the Hirata river with wasted hot water. The water temperature in Hirata rive is increased by wasted hot water by 10 degree C. The impacts of the developments of steam power generations on hot spring water and groundwater in downstream are also evaluated in Beppu. The decreases in temperature and volume of the hot spring water and groundwater after the development are concerning. Stakeholder analysis related to hot spa and power generation business and others in Beppu showed common interests in community development among stakeholders and gaps in prerequisite knowledge and recognition of the geothermal resource in terms of economic/non-economic value and utilization as power generation/hot-spring. We screened stakeholders of four categories (hot spring resorts inhabitants, industries, supporters, environmentalists), and set up three communities consisting of 50 persons of the above categories. One remarkable result regarding the pros and cons of geothermal power in general terms was that the supporter count increased greatly while the neutralities count
Determination of recharge and evolutionary study in new wells at Berlin geothermal field using isotopes
CEL have been made a preliminary study at Berlin geothermal field in order to estimate the recharge area. The results using isotopic data since 1996 to date shows an average altitude of 1350 masl. This value is in agreement with hydrological and geological studies, which correspond to an infiltration zone located around the Berlin-Tecapa complex. Isotopic composition from Laguna de Alegria (LA) located in the same complex and Rio Lempa located 12 km away from the field shows that there is not relation with the recharge of the Berlin geothermal field. Also, an evolutionary study of the geothermal wells shows three definite groups: new wells, production wells and reinjection wells. Isotopic composition in recently drilled wells is changing with time, showing more depleted values than production wells in which isotopic composition is seated in the range δ18O = -3.5 per mille to δ18O = -3.9 per mille and δD=-42 per mille to δD = -45 per mille. It suggest new wells still have a mixture of geothermal water and water introduced along the drilling. Reinjection wells seems to have not impact over production wells, at least with the available information. Monitoring is still on. (author)
Open Questions on the Origin of Life at Anoxic Geothermal Fields
Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.
We have recently reconstructed the `hatcheries' of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells (Mulkidjanian et al. Proc Natl Acad Sci U S A 109:E821-830, 2012). These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K+, Zn2+, Mn2+, and phosphate. Thus, protocells must have evolved in habitats with a high K+/Na+ ratio and relatively high concentrations of Zn, Mn and phosphorous compounds. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapor-dominated zones of inland geothermal systems. Under an anoxic, CO2-dominated atmosphere, the ionic composition of pools of cool, condensed vapor at anoxic geothermal fields would resemble the internal milieu of modern cells. Such pools would be lined with porous silicate minerals mixed with metal sulfides and enriched in K+ ions and phosphorous compounds. Here we address some questions that have appeared in print after the publication of our anoxic geothermal field scenario. We argue that anoxic geothermal fields, which were identified as likely cradles of life by using a top-down approach and phylogenomics analysis, could provide geochemical conditions similar to those which were suggested as most conducive for the emergence of life by the chemists who pursuit the complementary bottom-up strategy.
<正>20141588 Guo Shiyan(Green Energy Geothermai Development Co.,SINOPEC,Xianyang 712000,China);Li Xiaojun Reservoir Stratum Characteristics and Geothermal Resources Potential of Rongcheng Uplift Geothermal Field in Baoding,Hebei Province(Chinese Journal of Geology,ISSN0563-5020,CN11-1937/P,48(3),2013,p.922-931,2 illus.,4 tables,10 refs.)Key words:geothermal fields,Hebei Province
Case history report on East Mesa and Cerro Prieto geothermal fields
Davis, DG.; Sanyal, S.K.
Well log analysis as applied to the geothermal industry is one of the areas of technology in great need of further development. One means of improving log analysis technology is to study case histories of the past uses of log analysis as applied to specific fields. The project described in this report involved case history studies on two well-known geothermal areas in North America: the East Mesa field in California and the Cerro Prieto field in Mexico. Since there was considerably more pertinent material available on East Mesa, a major part of the effort on this project was devoted to studying the East Mesa field. One particular problem that first came to attention when studying the Cerro Prieto data was the difficulty in determining actual formation temperature at the time of logging. Since the temperature can have a significant effect on well log readings, an accurate temperature determination was considered to be important.
Inverse modeling and forecasting for the exploitation of the Pauzhetsky geothermal field, Kamchatka, Russia
Finsterle, Stefan; Kiryukhin, A.V.; Asaulova, N.P.; Finsterle, S.
A three-dimensional numerical model of the Pauzhetsky geothermal field has been developed based on a conceptual hydrogeological model of the system. It extends over a 13.6-km2 area and includes three layers: (1) a base layer with inflow; (2) a geothermal reservoir; and (3) an upper layer with discharge and recharge/infiltration areas. Using the computer program iTOUGH2 (Finsterle, 2004), the model is calibrated to a total of 13,675 calibration points, combining natural-state and 1960-2006 exploitation data. The principal model parameters identified and estimated by inverse modeling include the fracture permeability and fracture porosity of the geothermal reservoir, the initial natural upflow rate, the base-layer porosity, and the permeabilities of the infiltration zones. Heat and mass balances derived from the calibrated model helped identify the sources of the geothermal reserves in the field. With the addition of five makeup wells, simulation forecasts for the 2007-2032 period predict a sustainable average steam production of 29 kg/s, which is sufficient to maintain the generation of 6.8 MWe at the Pauzhetsky power plant.
Hydraulic model and steam flow numerical simulation of the Cerro Prieto geothermal field, Mexico, pipeline network
The development of a hydraulic model and numerical simulation results of the Cerro Prieto geothermal field (CPGF) steam pipeline network are presented. Cerro Prieto is the largest water-dominant geothermal field in the world and its transportation network has 162 producing wells, connected through a network of pipelines that feeds 13 power-generating plants with an installed capacity of 720 MWe. The network is about 125 km long and has parallel high- and low-pressure networks. Prior to this study, it was suspected that steam flow stagnated or reversed from its planned direction in some segments of the network. Yet, the network complexity and extension complicated the analysis of steam transport for adequate delivery to the power plants. Thus, a hydraulic model of the steam transportation system was developed and implemented numerically using an existing simulator, which allowed the overall analysis of the network in order to quantify the pressure and energy losses as well as the steam flow direction in every part of the network. Numerical results of the high-pressure network were obtained which show that the mean relative differences between measured and simulated pressures and flowrates are less than 10%, which is considered satisfactory. Analysis of results led to the detection of areas of opportunity and to the recommendation of changes for improving steam transport. A main contribution of the present work is having simulated satisfactorily the longest (to our knowledge), and probably the most complex, steam pipeline network in the world. - Highlights: • Extensive literature review of flow models of geothermal steam gathering networks. • Hydraulic model of the Cerro Prieto geothermal field steam network. • Selection and validation of the employed pressure-drop model. • Numerical flow simulation of the world's largest geothermal steam gathering network. • Detailed network pressure drop analysis and mapping of steam flow distribution
Did stresses from the Cerro Prieto Geothermal Field influence the El Mayor-Cucapah rupture sequence?
Trugman, Daniel T.; Borsa, Adrian A.; Sandwell, David T.
The Mw 7.2 El Mayor-Cucapah (EMC) earthquake ruptured a complex fault system in northern Baja California that was previously considered inactive. The Cerro Prieto Geothermal Field (CPGF), site of the world's second largest geothermal power plant, is located approximately 15 km to the northeast of the EMC hypocenter. We investigate whether anthropogenic fluid extraction at the CPGF caused a significant perturbation to the stress field in the EMC rupture zone. We use Advanced Land Observing Satellite interferometric synthetic aperture radar data to develop a laterally heterogeneous model of fluid extraction at the CPGF and estimate that this extraction generates positive Coulomb stressing rates of order 15 kPa/yr near the EMC hypocenter, a value which exceeds the local tectonic stressing rate. Although we cannot definitively conclude that production at the CPGF triggered the EMC earthquake, its influence on the local stress field is substantial and should not be neglected in local seismic hazard assessments.
Results of investigations at the Zunil geothermal field, Guatemala: Well logging and brine geochemistry
Adams, A.; Dennis, B.; Van Eeckhout, E.; Goff, F.; Lawton, R.; Trujillo, P.E.; Counce, D.; Archuleta, J. (Los Alamos National Lab., NM (USA)); Medina, V. (Instituto Nacional de Electrificacion, Guatemala City (Guatemala). Unidad de Desarollo Geotermico)
The well logging team from Los Alamos and its counterpart from Central America were tasked to investigate the condition of four producing geothermal wells in the Zunil Geothermal Field. The information obtained would be used to help evaluate the Zunil geothermal reservoir in terms of possible additional drilling and future power plant design. The field activities focused on downhole measurements in four production wells (ZCQ-3, ZCQ-4, ZCQ-5, and ZCQ-6). The teams took measurements of the wells in both static (shut-in) and flowing conditions, using the high-temperature well logging tools developed at Los Alamos National Laboratory. Two well logging missions were conducted in the Zunil field. In October 1988 measurements were made in well ZCQ-3, ZCQ-5, and ZCQ-6. In December 1989 the second field operation logged ZCQ-4 and repeated logs in ZCQ-3. Both field operations included not only well logging but the collecting of numerous fluid samples from both thermal and nonthermal waters. 18 refs., 22 figs., 7 tabs.
<正>20131088 Fan Difu (Geological Survey of Jiangsu Province , Nanjing 210018 , China ); Xu Xueqiu Origin Study of Geothermal Field in Xiaoyangkou of Rudong County in Jiangsu (Journal of Geology , ISSN1674-3636 , CN32-1796/P , 36 (2), 2012 , p.192-197 , 3illus. , 9refs.) Key words : geothermal fields , Jiangsu Province
Fracture mapping in geothermal fields with long-offset induction logging
Wilt, M.; Takasugi, Shinji; Uchida, Toshihiro [and others
The mapping of producing fractures in a geothermal field is an important technical objective in field development. Locating, orienting, and assessing producing fractures can guide drilling programs and optimize the placement of production and injection wells. A long-offset multicomponent borehole induction resistivity tool capable of surviving the high temperatures encountered in geothermal wells has recently been developed in a NEDO project, {open_quotes}Deep-Seated Geothermal Reservoirs,{close_quotes} and tested in a high temperature environment. Several characteristics of this device make it ideal for detecting producing fractures. Whereas commercial induction logging devices have source-receiver separations of 1 m, this device has multiple sensors with separations up to 8 m, allowing for deeper penetration and the ability to straddle fracture-induced washout zones in boreholes. The three-component measurements also make it possible to map the strike and inclination of nearby fractures and other three-dimensional structures. This, in turn, allows for accurate projection of these structures into the space between wells. In this paper, we describe the design of the tool and show results of a performance test carried out in an oil-field steam flood. Data from vertical sensors are compared to conventional logging results and indicate the recent formation of a low-resistivity zone associated with high temperatures due to steam flood breakthrough. Horizontal field data indicate that the high-temperature zone is irregular in the vicinity of the borehole and more pronounced closest to the steam injector.
Field trip guide to the Valles Caldera and its geothermal systems
Goff, F.E.; Bolivar, S.L.
This field trip guide has been compiled from extensive field trips led at Los Alamos National Laboratory during the past six years. The original version of this guide was designed to augment a workshop on the Valles Caldera for the Continental Scientific Drilling Program (CSDP). This workshop was held at Los Alamos, New Mexico, 5-7 October 1982. More stops were added to this guide to display the volcanic and geothermal features at the Valles Caldera. The trip covers about 90 miles (one way) and takes two days to complete; however, those who wish to compress the trip into one day are advised to use the designated stops listed in the Introduction. Valles Caldera and vicinity comprise both one of the most exciting geothermal areas in the United States and one of the best preserved Quaternary caldera complexes in the world.
Slope stability analysis of landslide in Wayang Windu Geothermal Field, Pangalengan, West Java Province, Indonesia
Yuhendar, A. H.; Wusqa, U.; Kartiko, R. D.; Raya, N. R.; Misbahudin
Large-scale landslide occurred in Margamukti village, Pangalengan, Bandung Regency, West Java Province, Indonesia. The landslide damaged geothermal gas pipeline along 300 m in Wayang Windu Geothermal Field. Based on field observation, landslide occured in rotational sliding movement. Laboratory analysis were conducted to obtain the characteristics of the soil. Based on the condition of the landslide in this area, the Factor of Safety can be simulated by the soil mechanics approach. Factor of safety analysis based on soil cohesion and internal friction angle was conducted using manual sensitivity analysis for back analysis. The analysis resulted soil cohesion in critical condition (FS<1) is 6.01 kPa. This value is smaller than cohesion of undisturbed slope soil sample. Water from rainfall is the most important instability factors in research area. Because it decreases cohesion in soils and increases weight and pore water pressure in granular media.
Field tests of 2- and 40-tube condensers at the East Mesa Geothermal Test Site
Murphy, R.W.; Domingo, N.
Two water-cooled isobutane condensers, one with 2 tubes and one with 40 tubes, were subjected to field tests at the East Mesa Geothermal Test Site to assess relative heat transfer performance in both surface evaporator and direct-contact evaporator modes. The five groups of tests established that field performance was below earlier laboratory-determined levels and that direct-contact evaporator mode performance was poorer than that for the surface evaporator mode. In all test situations, fluted condenser tubes performed better than smooth condenser tubes. Cooling water quality had no significant effect on performance, but brine preflash in the direct-contact mode did promote some relative performance improvement. Important implications of these results for binary geothermal power plants are that (1) working-fluid-side impurities can significantly degrade heat transfer performance of the power plant condensers and (2) provisions for minimizing such impurities may be required.
Open Questions on the Origin of Life at Anoxic Geothermal Fields
Mulkidjanian, Armen Y; Bychkov, Andrew Yu.; Dibrova, Daria V.; Michael Y. Galperin; Koonin, Eugene V
We have recently reconstructed the 'hatcheries' of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells (Mulkidjanian et al.: Origin of first cells at terrestrial, anoxic geothermal fields. Proc Natl Acad Sci USA 2012, 109:E821–830). These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K+, Zn2+, Mn2+, a...
Development of a geothermal resource in a fractured volcanic formation: Case study of the Sumikawa Geothermal Field, Japan. Final report, May 1, 1995--November 30, 1997
Garg, S.K.; Combs, J.; Pritchett, J.W. [and others
The principal purpose of this case study of the Sumikawa Geothermal Field is to document and to evaluate the use of drilling logs, surface and downhole geophysical measurements, chemical analyses and pressure transient data for the assessment of a high temperature volcanic geothermal field. This comprehensive report describes the work accomplished during FY 1993-1996. A brief review of the geological and geophysical surveys at the Sumikawa Geothermal Field is presented (Section 2). Chemical data, consisting of analyses of steam and water from Sumikawa wells, are described and interpreted to indicate compositions and temperatures of reservoir fluids (Section 3). The drilling information and downhole pressure, temperature and spinner surveys are used to determine feedzone locations, pressures and temperatures (Section 4). Available injection and production data from both slim holes and large-diameter wells are analyzed to evaluate injectivity/productivity indices and to investigate the variation of discharge rate with borehole diameter (Section 5). New interpretations of pressure transient data from several wells are discussed (Section 6). The available data have been synthesized to formulate a conceptual model for the Sumikawa Geothermal Field (Section 7).
Microearthquake Study of the Salton Sea Geothermal Field, California: Evidence of Stress Triggering
A digital network of 24 seismograph stations was operated from September 15, 1987 to September 30, 1988, by Lawrence Livermore National Laboratory and Unocal as part of the Salton Sea Scientific Drilling Project to study seismicity related to tectonics and geothermal activity near the drilling site. More than 2001 microearthquakes were relocated in this study in order to image any pervasive structures that may exist within the Salton Sea geothermal field. First, detailed velocity models were obtained through standard 1-D inversion techniques. These velocity models were then used to relocate events using both single event methods and Double-Differencing, a joint hypocenter location method. An anisotropic velocity model was built from anisotropy estimates obtained from well logs within the study area. During the study period, the Superstition Hills sequence occurred with two moderate earthquakes of MS 6.2 and MS 6.6. These moderate earthquakes caused a rotation of the stress field as observed from the inversion of first motion data from microearthquakes at the Salton Sea geothermal field. Coulomb failure analysis also indicates that microearthquakes occurring after the Superstition Hills sequence are located within a region of stress increase suggesting stress triggering caused by the moderate earthquakes
Microearthquake Study of the Salton Sea Geothermal Field, California: Evidence of Stress Triggering - Masters Thesis
Holland, Austin Adams
A digital network of 24 seismograph stations was operated from September 15, 1987 to September 30, 1988, by Lawrence Livermore National Laboratory and Unocal as part of the Salton Sea Scientific Drilling Project to study seismicity related to tectonics and geothermal activity near the drilling site. More than 2001 microearthquakes were relocated in this study in order to image any pervasive structures that may exist within the Salton Sea geothermal field. First, detailed velocity models were obtained through standard 1-D inversion techniques. These velocity models were then used to relocate events using both single event methods and Double-Differencing, a joint hypocenter location method. An anisotropic velocity model was built from anisotropy estimates obtained from well logs within the study area. During the study period, the Superstition wills sequence occurred with two moderate earthquakes of MS 6.2 and MS 6.6. These moderate earthquakes caused a rotation of the stress field as observed from the inversion of first motion data from microearthquakes at the Salton Sea geothermal field. Coulomb failure analysis also indicates that microearthquakes occurring after the Superstition Hills sequence are located within a region of stress increase suggesting stress triggering caused by the moderate earthquakes.
Strontium isotope as an indicator of fluid residence from selected geothermal fields in China
The purpose of this study is to develop a new indicator of fluid residence in complex geothermal systems. The method is based on a serious of assumptions in geothermal systems. Firstly, the Yangbajain geothermal field of Tibet is chosen to study the behaviors of strontium isotope and verify these assumptions when a deeper thermal fluid ascends. In the past years, two reservoirs have been identified at different depths in the Yangbajain field. A shallow reservoir is found at depths less than 450m, with temperature varying from 150 deg. C to 170 deg. C and decreasing toward the southeast. Parent rock in the shallow reservoir is altered Himalayan granite in the northwest part of the field and Quaternary alluvium in the southeast part. A deep reservoir is found at depths in the range from 750m to 1400m, with temperature higher than 250 deg. C. Parent rock in the deep reservoir is fractured Himalayan granite. Both thermal fluids from the shallow and deep reservoir and cold groundwater are collected for the analysis of chemical compositions and strontium isotope. Rock samples are also collected at different depths in wells for strontium isotope measurement
Reflection seismic imaging in the volcanic area of the geothermal field Wayang Windu, Indonesia
Polom, Ulrich; Wiyono, Wiyono; Pramono, Bambang; Krawczyk, CharLotte M.
Reflection seismic exploration in volcanic areas is still a scientific challenge and requires major efforts to develop imaging workflows capable of an economic utilization, e.g., for geothermal exploration. The SESaR (Seismic Exploration and Safety Risk study for decentral geothermal plants in Indonesia) project therefore tackles still not well resolved issues concerning wave propagation or energy absorption in areas covered by pyroclastic sediments using both active P-wave and S-wave seismics. Site-specific exploration procedures were tested in different tectonic and lithological regimes to compare imaging conditions. Based on the results of a small-scale, active seismic pre-site survey in the area of the Wayang Windu geothermal field in November 2012, an additional medium-scale active seismic experiment using P-waves was carried out in August 2013. The latter experiment was designed to investigate local changes of seismic subsurface response, to expand the knowledge about capabilities of the vibroseis method for seismic surveying in regions covered by pyroclastic material, and to achieve higher depth penetration. Thus, for the first time in the Wayang Windu geothermal area, a powerful, hydraulically driven seismic mini-vibrator device of 27 kN peak force (LIAG's mini-vibrator MHV2.7) was used as seismic source instead of the weaker hammer blow applied in former field surveys. Aiming at acquiring parameter test and production data southeast of the Wayang Windu geothermal power plant, a 48-channel GEODE recording instrument of the Badan Geologi was used in a high-resolution configuration, with receiver group intervals of 5 m and source intervals of 10 m. Thereby, the LIAG field crew, Star Energy, GFZ Potsdam, and ITB Bandung acquired a nearly 600 m long profile. In general, we observe the successful applicability of the vibroseis method for such a difficult seismic acquisition environment. Taking into account the local conditions at Wayang Windu, the method is
Monitoring production using surface deformation: the Hijiori test site and the Okuaizu geothermal field
Production in geothermal reservoirs often leads to observable surface displacement. As shown in this paper, there is a direct relationship between such displacement and reservoir dynamics. This relationship is exploited in order to image fluid flow at two geothermal field sites. At the first locality, the Hijiori Hot Dry Rock (HDR) test site, 17 tilt meters record deformation associated with a 2.2 km deep injection experiment. Images of fluid migration along a ring fracture system of the collapsed Hijiori caldera are obtained. At the Okuaizu geothermal field, leveling and tilt meter data provide constraints on long- and short-term fluid movement within the reservoir. A set of 119 leveling data suggest that the north-to-northeast trending Takiyagawa fault acts as a barrier to flow. The northwesterly oriented Chinoikezawa and Sarukurazawa faults appear to channel fluid from the southeast. The tilt data from Okuaizu indicate that a fault paralleling the Takiyagawa fault zone acts as a conduit to transient flow, on a time scale of several weeks. The volume strain in a region adjacent to the injection wells reaches a maximum and then decreases with time. The transient propagation of fluid along the fault may be due to pressure build-up, resulting from the re-initiation of injection. (author)
Imaging the deep source of the Rotorua and Waimangu geothermal fields, Taupo Volcanic Zone, New Zealand
Heise, W.; Caldwell, T. G.; Bertrand, E. A.; Hill, G. J.; Bennie, S. L.; Palmer, N. G.
Magnetotelluric data were recorded in a 45 × 10 km band crossing the Rotorua and Waimangu geothermal fields in the northern part of the Taupo Volcanic Zone in the central North Island of New Zealand. 3-D inverse modelling of these data show that beneath the low resistivity areas marking the near surface geothermal fields, localised electrically conductive zones are present in the crust below about 2.5 and 3.5 km depth at Rotorua and Waimangu, respectively. At increasing depth these conductive zones broaden and appear to merge with a larger conductive zone at 8 km depth situated between the geothermal systems. At Rotorua the top of the conductive zone is situated directly beneath the area of greatest surface heat and gas discharge. At Waimangu the uppermost part of the deeper conductive zone is situated beneath the western part of Lake Rotomahana, also an area of intense surface thermal activity and high heat flux. The localised conductive zones are interpreted to be high temperature (quasi-magmatic) fluids rising from a broader zone of partial melt at deeper levels.
Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field
Valette-Silver, J.N.; Esquer P., I.; Elders, W.A.; Collier, P.C.; Hoagland, J.R.
A study of the mineralogical changes associated with these hydrothermal vents was initiated with the aim of developing possible exploration tools for geothermal resources. The Cerro Prieto reservoir has already been explored by extensive deep drilling so that relationships between surface manifestations and deeper hydrothermal processes could be established directly. Approximately 120 samples of surface sediments were collected both inside and outside of the vents. The mineralogy of the altered sediments studied appears to be controlled by the type of emission. A comparison between the changes in mineralogy due to low temperature hydrothermal activity in the reservoir, seen in samples from boreholes, and mineralogical changes in the surface emission samples shows similar general trends below 180 C: increase of quartz, feldspar and illite, with subsequent disappearance of kaolinite, montmorillonite, calcite and dolomite. These mineral assemblages seem to be characteristic products of the discharge from high intensity geothermal fields.
Reservoir Characterization around Geothermal Field, West Java, Indonesia Derived from 4-D Seismic Tomography
Verdhora Ry, Rexha; Nugraha, A. D.
Observation of micro-seismic events induced by intensive geothermal exploitation in a particular geothermal field, located in West Java region, Indonesia was used to detect the fracture and permeability zone. Using local monitoring seismometer network, tomographic inversions were conducted for the three-dimensional Vp, Vs, and Vp/Vs structure of the reservoir for January - December 2007, January - December 2008, and January - December 2009. First, hypocenters location was relocated using joint hypocenter determination (JHD) method in purpose to estimate best location. Then, seismic tomographic inversions were conducted using delay time tomography for dataset of every year respectively. The travel times passing through the three-dimensional velocity model were calculated using ray tracing pseudo-bending method. Norm and gradient damping were added to constrain blocks without ray and to produce smooth solution model. The inversion algorithm was developed in Matlab environment. Our tomographic inversion results from 3-years of observations indicate the presence of low Vp, low Vs, and low Vp/Vs ratio at depths of about 1 - 3 km below sea level. These features were interpreted may be related to steam-saturated rock in the reservoir area of this geothermal field. The locations of the reservoir area were supported by the data of well- trajectory, where the zones of high Vp/Vs were observed around the injection wells and the zones of low Vp/Vs were observed around the production wells. The extensive low Vp/Vs anomaly that occupies the reservoir is getting stronger during the 3-years study period. This is probably attributed to depletion of pore liquid water in the reservoir and replacement with steam. Continuous monitoring of Vp, Vs, and Vp/Vs is an effective tool for geothermal reservoir characterization and depletion monitoring and can potentially provide information in parts of the reservoir which have not been drilled.
Geochemical Modelling of the High-Temperature Mahanagdong Geothermal Field, Leyte, Philippines
Angcoy, Erlindo C., 1975-
The high-temperature and liquid-dominated Mahanagdong geothermal field has supplied steam since 1997 to power plants with total installed capacity of 180 MWe. A geochemical assessment of the field is presented based on analytical data of fluids sampled at the wellheads of 26 wet-steam wells. The pH of the liquid samples ranges from 3 to 8 as measured on-site. Analyses of the water samples include major and minor elements. With the aid of speciation programs, the analytical data were used ...
Seismicity and deformation in the Coso Geothermal field from 2000 to 2012
Kaven, J. Ole; Hickman, Stephen H.; Davatzes, Nicholas C.
Induced micro-seismicity in geothermal reservoirs, in particular in enhanced geothermal systems (EGS), is an intended byproduct of injection and production, as it often indicates the generation of permeability pathways on either pre-existing or newly generated faults and fractures. The hazard of inducing an earthquake large enough to cause damage to surface structures, however, is not easily avoided and has led to termination of geothermal projects. To explore the physical processes leading to damaging earthquakes, we investigate the evolution of seismicity and the factors controlling the migration, moment release rate, and structure within the seismicity in the Coso Geothermal Field (CGF). The CGF has been in production since the 1980s and includes both naturally occurring geothermal resources and portions of the reservoir that are EGS projects. We report on seismicity in the CGF that has been relocated with high precision double-difference relocation and simultaneous velocity inversion to understand the reservoir compartmentalization, in particular, where boundaries to flow exist both vertically and horizontally. We also calculate moment magnitudes (Mw) from the initial displacement pulse of the seismograms to relate moment directly to the deformation. We find that two distinct compartments form the CGF, which are divided by an aseismic gap that also shows a relatively low Vp/Vs ratio. Further, we find that events with Mw> 3.5 tend to map onto larger fault structures that are imaged by the relocated seismicity. We relate the temporal and spatial migration of moment release rate to the injection and production records in the reservoir by employing a thermo-poro-elastic finite element model in which the compartment boundaries are defined by the seismicity. We find that pore pressure effects alone are not responsible for the migration of seismicity and that poro-elastic and thermo-elastic strain changes can account for more of the observed moment release rate than
Hydro-geochemical and isotopic fluid evolution of the Los Azufres geothermal field, Central Mexico
Hydrothermal alteration at Los Azufres geothermal field is mostly propylitic with a progressive dehydration with depth and temperature increase. Argillic and advanced argillic zones overlie the propylitic zone owing to the activity of gases in the system. The deepest fluid inclusions (proto-fluid) are liquid-rich with low salinity, with NaCl dominant fluid type and ice melting temperatures (Tmi) near zero (0 deg C), and salinities of 0.8 wt% NaCl equivalent. The homogenization temperature (Th) = 325 ± 5 deg C. The boiling zone shows Th = ±300 deg C and apparent salinities between 1 and 4.9 wt% NaCl equivalent, implying a vaporization process and a very important participation of non-condensable gases (NCGs), mostly CO2. Positive clathrate melting temperatures (fusion) with Th = 150 deg C are observed in the upper part of the geothermal reservoir (from 0 to 700 m depth). These could well be the evidence of a high gas concentration. The current water produced at the geothermal wells is NaCl rich (geothermal brine) and is fully equilibrated with the host rock at temperatures between T = 300 and 340 deg C. The hot spring waters are acid-sulfate, indicating that they are derived from meteoric water heated by geothermal steam. The NCGs related to the steam dominant zone are composed mostly of CO2 (80-98% of all the gases). The gases represent between 2 and 9 wt% of the total mass of the fluid of the reservoir. The authors interpret the evolution of this system as deep liquid water boiling when ascending through fractures connected to the surface. Boiling is caused by a drop of pressure, which favors an increase in the steam phase within the brine ascending towards the surface. During this ascent, the fluid becomes steam-dominant in the shallowest zone, and mixes with meteoric water in perched aquifers. Stable isotope compositions (δ18O-δD) of the geothermal brine indicate mixing between meteoric water and a minor magmatic component. The enrichment in δ18O is due to
Detailed microearthquake studies at the Cerro Prieto geothermal field
Majer, E.L. (Lawrence Berkeley Lab., CA); McEvilly, T.V.
There appears to be an increase in seismic activity within the Cerro Prieto production zone since early 1978. The microearthquake activity is now more or less constant at a rate of 2 to 3 events per day. The b-values within the field are significantly higher inside the production zone than are those for events on faults outside of the production region. The earthquakes seem to be controlled by the Hidalgo fault, although slight clustering was observed in the center of the main production region. The earthquakes within the production zone may reflect the reservoir dynamics associated with heat and mass withdrawal. Mechanisms such as volume change, thermal stresses and weakening of materials associated with boiling (i.e., phase changes, dissolution) may all be responsible for the increased seismic activity. Although a small reinjection program has started, the pressure drawdown conditions existing within the field would imply that increased pore pressure resulting from the injection activities is not responsible for the increased seismic activity.
The Ahuachapan geothermal field, El Salvador: Exploitation model, performance predictions, economic analysis
Ripperda, M.; Bodvarsson, G.S.; Lippmann, M.J.; Witherspoon, P.A. (Lawrence Berkeley Lab., CA (United States)); Goranson, C. (Geothermal Consultant Richmond, California (USA))
The Earth Sciences Division of Lawrence Berkeley Laboratory (LBL) is conducting a reservoir evaluation study of the Ahuachapan geothermal field in El Salvador. This work is being performed in cooperation with the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) and the Los Alamos National Laboratory (LANL) with funding from the US Agency for International Development (USAID). This appendix to the report describes the work done during the second year of the study (FY89--90). The first year's report included (1) the development of geological and conceptual models of the field, (2) the evaluation of the reservoir's initial thermodynamic and chemical conditions and their changes during exploitation, (3) the evaluation of interference test data and the observed reservoir pressure decline and (4) the development of a natural state model for the field. In these appendices the results of reservoir engineering studies to evaluate different production-injection scenarios for the Ahuachapan geothermal field are discussed. The purpose of the work was to evaluate possible reservoir management options to enhance as well as to maintain the productivity of the field during a 30-year period (1990--2020). The ultimate objective was to determine the feasibility of increasing the electrical power output at Ahuachapan from the current level of about 50 MW{sub e} to the total installed capacity of 95 MW{sub e}. the flow rate and flowing enthalpy are shown for 1975--1990 and extrapolated out to 2015. Future temperature distributions are predicted.
The Ahuachapan geothermal field, El Salvador: Exploitation model, performance predictions, economic analysis
Ripperda, M.; Bodvarsson, G.S.; Lippmann, M.J.; Witherspoon, P.A.; Goranson, C.
The Earth Sciences Division of Lawrence Berkeley Laboratory (LBL) is conducting a reservoir evaluation study of the Ahuachapan geothermal field in El Salvador. This work is being performed in cooperation with the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) and the Los Alamos National Laboratory (LANL) with funding from the US Agency for International Development (USAID). This report describes the work done during the second year of the study (FY89--90). The first year's report included (1) the development of geological and conceptual models of the field, (2) the evaluation of the reservoir's initial thermodynamic and chemical conditions and their changes during exploitation, (3) the evaluation of interference test data and the observed reservoir pressure decline and (4) the development of a natural state model for the field. In the present report the results of reservoir engineering studies to evaluate different production-injection scenarios for the Ahuachapan geothermal field are discussed. The purpose of the work was to evaluate possible reservoir management options to enhance as well as to maintain the productivity of the field during a 30-year period (1990--2020). The ultimate objective was to determine the feasibility of increasing the electrical power output at Ahuachapan from the current level of about 50 MW{sub e} to the total installed capacity of 95 MW{sub e}. 20 refs., 75 figs., 10 tabs.
Chemical and isotopic studies of fluids in the Bacon-Manito geothermal field, Philippines
Chemical and isotopic data from springs rainfall and wells have been used to characterize the fluids and to identify the major reservoir processes at Bacon-Manito geothermal field, Philippines. The deep reservoir fluid is postulated to be heated to about 325 deg. C and have 7500-8500 mg/kg chloride. Its chemical and isotopic composition is best characterized by wells OP-3D and OP-4D. Spring isotopic data show that their discharges are predominantly meteoric in origin, with a few following a simple evaporation trend. Chloride-enthalpy and chlorid-δ18O relations reveal that the upflowing geothermal reservoir fluid undergoes: (1) dilution with meteroic water, (2) conductive cooling as these move away, (3) mixing with steam condensate, and (4) vapor gain. Well gas chemistry points to the absence of direct magmatic contributions while it is shown that the equilibrium reaction CH4 + 2H2O = CO2 + 4H2 is likely to be established. The observed positive 18O shifts of well waters relative to the local water meteoric line were considered to be due primarily to mixing of deeply-seated ''andesitic'' and meteoric waters while water-rock interaction could not be ruled out. Finally, a conceptual geochemical model of the geothermal system is proposed. (author). 21 refs, 12 figs, 5 tabs
Relationship between water chemistry and sediment mineralogy in the Cerro Prieto geothermal field: a preliminary report
Valette-Silver, J.N. (Univ. de Perpignan, France); Thompson, J.M.; Ball, J.W.
The chemical compositions of waters collected from the Cerro Prieto geothermal production wells and hydrothermal emanations are different. Compared to the Cerro Prieto well waters, the surficial waters generally contain significantly less potassium, slightly less calcium and chloride, and significantly more magnesium and sulfate. In comparison to the unaltered sediments, the changes in the mineralogy of the altered sediments appear to be controlled by the type of emanation (well, spring, mud pot, geyser, fumarole, or cold pool). However, an increase in quartz and potassium feldspar percentages seems to be characteristic of the majority of the sediments in contact with geothermal fluids. Preliminary attempts to model the chemical processes occurring in the Cerro Prieto geothermal field using chemical equilibrium calculations are reported. For this purpose the chemical compositions of thermal waters (well and surficial emanation) were used as input data to make calculations with SOLMNEQ and WATEQ2 computer programs. Then the theoretical mineral composition of altered sediments was predicted and compared to the mineralogy actually observed in the solid samples.
A method of fundamental solutions in poroelasticity to model the stress field in geothermal reservoirs
Augustin, Matthias Albert
This monograph focuses on the numerical methods needed in the context of developing a reliable simulation tool to promote the use of renewable energy. One very promising source of energy is the heat stored in the Earth's crust, which is harnessed by so-called geothermal facilities. Scientists from fields like geology, geo-engineering, geophysics and especially geomathematics are called upon to help make geothermics a reliable and safe energy production method. One of the challenges they face involves modeling the mechanical stresses at work in a reservoir. The aim of this thesis is to develop a numerical solution scheme by means of which the fluid pressure and rock stresses in a geothermal reservoir can be determined prior to well drilling and during production. For this purpose, the method should (i) include poroelastic effects, (ii) provide a means of including thermoelastic effects, (iii) be inexpensive in terms of memory and computational power, and (iv) be flexible with regard to the locations of data ...
Modeling studies of the Ahuachapan geothermal field, El Salvador
Aunzo, Z.; Steingrimsson, B.; Bodvarsson, G.S. (Lawrence Berkeley Lab., CA (USA)); Escobar, C.; Quintanilla, A. (Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) (El Salvador))
Modeling studies of Ahuachapan include analyses of interference test data, modeling of the fieldwide pressure decline and the development of a three-dimensional natural state model of the field. The main objective of this work is to obtain reasonable estimates for the transmissivity and storativity of the reservoir and to investigate fluid and heat flow patterns in the system. The analyses of the interference test data and the long term pressure decline data indicate that the average reservoir transmissivity is about 30 Dm and the storativity about 3.5 {times} 10{sup {minus}6} m/Pa. The natural state modeling supports an overall average transmissivity of 25--35 Dm and indicates that the system is recharged with 255{degree}C hot water at a rate of about 225 kg/s. The total thermal throughflow for the Ahuachapan system is estimated to be about 250 MW{sub t}. 10 refs., 11 figs., 3 tabs.
Distributed Acoustic Sensing Technology in a Magmatic Geothermal Field - First Results From a Survey in Iceland
Reinsch, Thomas; Jousset, Philippe; Henninges, Jan; Blanck, Hanna
Seismic methods are particularly suited for investigating the Earth's subsurface. Compared to surface-measurements , wellbore measurements can be used to acquire more detailed information about rock properties and possible fluid pathways within a geothermal reservoir. For high temperature geothermal wells, however, ambient temperatures are often far above the operating temperature range of conventional geophones. One way to overcome this limitation is the application of fiber optic sensor systems, where only the passive optical fiber is subjected to downhole conditions. Their applicability is thus determined by the operating temperature range of the optical fiber. Choosing appropriate fibers, such sensor systems can be operated at temperatures far above 200°C. Along an optical fiber, the distributed acoustic sensing technology (DAS) can be used to acquire acoustic signals with a high spatial and temporal resolution. Previous experiments have shown that the DAS technology is well suited for active seismic measurements. Within the framework of the EC funded project IMAGE, a fiber optic cable was deployed in a newly drilled geothermal well (RN-34) within the Reykjanes geothermal field, Iceland. Additionally, a >15 km fiber optic cable, already available at the surface, was connected to a DAS read-out unit. Acoustic data was acquired continuously for 9 days. Hammer shots were performed at the wellhead as well as along the surface cable in order to locate individual acoustic traces and calibrate the spatial distribution of the acoustic information. During the monitoring period both signals from on- and offshore explosive sources and natural seismic events could be recorded. We compare the fiber optic data to conventional seismic records from a dense seismic network deployed on the Reykjanes in the course of the IMAGE project. Here, first results from the seismic survey will be presented.
Conversion of back pressure type turbines to cross compound type for Los Azufres geothermal field, Mexico
Cadenas, Roberto; Fernandez, Maria Elena [Gerencia de Proyectos Geotermoelectricos de la Comision Federal de Electricidad, Morelia (Mexico)
This paper presents a case of converting geothermal back pressure turbines into cross compound condensing type. Comision Federal de Electricidad (CFE) is operating 16 back pressure turbines, 5 MW each, which were installed to investigate and evaluate several zones of the Mexican geothermal fields. Nine of these units are installed in Los Azufres geothermal field. The purpose of these units was to remain operating for some time and then be replaced by condensing units with better efficiencies. However, because of new fields are not available, it has became a necessity to get better efficiencies with the present units and leave them operating in their original sites for a longer time. The conversion of that turbines will allow to increase the power of each unit, from 5 MW to 8.5 MW, with competitive production costs and positive environmental effects. [Espanol] Se presenta un caso de conversion de turbinas tipo contrapresion a turbinas tipo cross compound. La Comision Federal de Electricidad (CFE) tiene en operacion 16 turbinas de contrapresion de 5 MW cada una, que fueron instaladas para investigar y evaluar diversas zonas de los campos geotermicos de Mexico. Nueve de esas unidades se encuentran en el campo de Los Azufres. Las expectativas de la empresa eran operar temporalmente estas unidades en algunos sitios de interes y posteriormente substituirlas por unidades a condensacion, de mejor eficiencia. Sin embargo, en este momento no se cuenta con nuevos campos productores para la reubicacion de las turbinas, siendo necesario mejorar su eficiencia a efecto de dejarlas operando como instalaciones permanentes en sus sitios originales. La conversion permitira incrementar la potencia de cada unidad de 5 MW a 8.5 MW, con costos de produccion competitivos y beneficios ambientales adicionales.
<正>20101802 Fang Bin (China University of Geosciences,Beijing 100083,China);Yang Yunjun Characteristics and Resource Evaluation of the Jiwa Geothermal Field in Central Qiangtang,Northern Tibet,China (Geological Bulletin of China,ISSN1671-
A Geologic, Hyrologic and Geochemical Model of the Serrazzano Zone of the Larderello Geothermal Field
Calorie, C.; Celati, R.; D' Amore, F.; Squarci, P.; Truesdell, A.
The large number of nonproductive wells lying along the northern and western margins of the Larderello field have indicated some boundaries of the productive area but have also prevented us, so far, from fully understanding the pheiomena controlling the behavior of the geothermal system in these areas. In 1980 ENEL re-opened some wells that had been shut-in immediately after drilling, thus offering us the possibility to complete the geochemical picture by means of numerous samplings of steam, gas and water in both productive and nonproductive wells. Some recent physical parameters measured in nonproductive and abandoned wells also helped in further defining the hydrogeological and thermal situation.
Rapid high temperature field test method for evaluation of geothermal calcite scale inhibitors
Asperger, R.G.
A test method is described which allows the rapid field testing of calcite scale inhibitors in high- temperature geothermal brines. Five commercial formulations, chosen on the basis of laboratory screening tests, were tested in brines with low total dissolved solids at ca 500 F. Four were found to be effective; of these, 2 were found to be capable of removing recently deposited scale. One chemical was tested in the full-flow brine line for 6 wks. It was shown to stop a severe surface scaling problem at the well's control valve, thus proving the viability of the rapid test method. (12 refs.)
Hydrothermal alteration in the EPF replacement wells, Olkaria Geothermal field, Kenya
Mungania, J. [Kenya Power & Lighting Co. Ltd., Naivasha (Kenya)
Olkaria Geothermal area is located in the central sector of the Kenya, Rift Valley. A 45MW Geothermal power station has been operational at Olkaria since 1985 supplied by 22 of the 26 wells drilled in the Eastern production field (EPF). Between 1988 and 1993, eight more wells referred to as {open_quote}replacement wells{close_quote} were drilled in the same field to boost steam supply to the station. Petrographic analyses of the drill cuttings is usually done to determine detail stratigraphy of the field, extends of hydrothermal activity, subsurface structures and other parameters which may influence production potential of a well. Analyses of the drill cuttings from the EPF wells show that: Variations in the whole rock alteration intensities correlate with differences in rocktypes. Permeable horizons, especially the productive feeder zones are well marked by enhanced hydrothermal minerals depositions, mainly quartz, calcite, pyrite and epidote. Other aspects of state of reservoir like boiling are signified by presence of bladed calcite.
Land subsidence caused by the East Mesa geothermal field, California, observed using SAR interferometry
Massonnet, D.; Holzer, T.; Vadon, H.
Interferometric combination of pairs of synthetic aperture radar (SAR) images acquired by the ERS-1 satellite maps the deformation field associated with the activity of the East Mesa geothermal plant, located in southern California. SAR interferometry is applied to this flat area without the need of a digital terrain model. Several combinations are used to ascertain the nature of the phenomenon. Short term interferograms reveal surface phase changes on agricultural fields similar to what had been observed previously with SEASAT radar data. Long term (2 years) interferograms allow the study of land subsidence and improve prior knowledge of the displacement field, and agree with existing, sparse levelling data. This example illustrates the power of the interferometric technique for deriving accurate industrial intelligence as well as its potential for legal action, in cases involving environmental damages. Copyright 1997 by the American Geophysical Union.
Moment tensor inversions of M ~ 3 earthquakes in the Geysers geothermal fields, California
Guilhem, A.; Hutchings, L.; Dreger, D. S.; Johnson, L. R.
Microearthquakes have come into high public awareness due to being induced by the development and exploitation of enhanced and natural geothermal fields, hydrofracturing, and CO2 sequestration sites. Characterizing and understanding the faulting process of induced earthquakes, which is generally achieved through moment tensor inversion, could both help in risk prediction and in reservoir development monitoring. However, this is a challenging task because of their lower signal-to-noise ratio at frequencies typically used in earthquake source analyses. Therefore, higher-resolution velocity models and modeling of seismic waves at higher frequencies are required. In this study, we examine both the potentials to obtain moment tensor solutions for small earthquakes and the uncertainty of those solutions. We utilize a short-period seismic network located in the Geysers geothermal field in northern California and limit our study to that which would be achieved by industry in a typical reservoir environment. We obtain full moment tensor solutions of M ~ 3 earthquakes using waveform modeling and first-motion inversions. We find that these two data sets give complimentary but yet different solutions. Some earthquakes correspond possibly to complex processes in which both shear and tensile failures occur simultaneously or sequentially. This illuminates the presence of fluids at depth and their role for the generation of these small-magnitude earthquakes. Finally, since first motions are routinely obtained for all magnitude earthquakes, our approach could be extended to small earthquakes where noise level and complex Green's functions prohibit using waveforms in moment tensor inversions.
Laboratory measurements of reservoir rock from the Geysers geothermal field, California
Lockner, D.A.; Summers, R.; Moore, D.; Byerlee, J.D.
Rock samples taken from two outcrops, as well as rare cores from three well bores at the Geysers geothermal field, California, were tested at temperatures and pressures similar to those found in the geothermal field. Both intact and 30?? sawcut cylinders were deformed at confining pressures of 200-1000 bars, pore pressure of 30 bars and temperatures of 150?? and 240??C. Thin-section and X-ray analysis revealed that some borehole samples had undergone extensive alteration and recrystallization. Constant strain rate tests of 10-4 and 10-6 per sec gave a coefficient of friction of 0.68. Due to the highly fractured nature of the rocks taken from the production zone, intact samples were rarely 50% stronger than the frictional strength. This result suggests that the Geysers reservoir can support shear stresses only as large as its frictional shear strength. Velocity of p-waves (6.2 km/sec) was measured on one sample. Acoustic emission and sliding on a sawcut were related to changes in pore pressure. b-values computed from the acoustic emissions generated during fluid injection were typically about 0.55. An unusually high b-value (approximately 1.3) observed during sudden injection of water into the sample may have been related to thermal cracking. ?? 1982.
Mantle-derived CO2 in Hot Springs of the Rehai Geothermal Field,Tengchong, China
REN Jianguo; WANG Xianbin; OUYANG Ziyuan
Gas concentrations and isotopic compositions of He and CO2 were determined on free gas samples from ten hot springs of the Rehai geothermal field, Tengchong, China. The results showed that hot-spring CO2 gas, together with He,was derived mainly from the mantle, indicating the accumulation of mantle-derived volatiles beneath the survey area. The δ13C values of CO2, higher than those of the typical mantle-derived carbon and the isotopic composition of hot-spring-free CO2 in unequilibrium with dissolved CO2, are recognized only in the Rehai geothermal field, suggesting that there seems to be a still-degassing magmatic intrusion at depths, which provides mantle-derived volatiles to the hydrothermal system above. The accumulation of those volatiles has probably played an important role in triggering earthquakes in this region.In addition, the isotopic characteristics of He and C also indicate that the magmatic intrusion seems to have been derived from the MORB source, and could be contaminated by crustal materials during its upwelling through the continental crust.
PNAS Plus: Origin of first cells at terrestrial, anoxic geothermal fields
Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.
All cells contain much more potassium, phosphate, and transition metals than modern (or reconstructed primeval) oceans, lakes, or rivers. Cells maintain ion gradients by using sophisticated, energy-dependent membrane enzymes (membrane pumps) that are embedded in elaborate ion-tight membranes. The first cells could possess neither ion-tight membranes nor membrane pumps, so the concentrations of small inorganic molecules and ions within protocells and in their environment would equilibrate. Hence, the ion composition of modern cells might reflect the inorganic ion composition of the habitats of protocells. We attempted to reconstruct the "hatcheries" of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells. These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K+, Zn2+, Mn2+, and phosphate. Thus, protocells must have evolved in habitats with a high K+/Na+ ratio and relatively high concentrations of Zn, Mn, and phosphorous compounds. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapor-dominated zones of inland geothermal systems. Under the anoxic, CO2-dominated primordial atmosphere, the chemistry of basins at geothermal fields would resemble the internal milieu of modern cells. The precellular stages of evolution might have transpired in shallow ponds of condensed and cooled geothermal vapor that were lined with porous silicate minerals mixed with metal sulfides and enriched in K+, Zn2+, and phosphorous compounds.
Pre-exploitation state of the Ahuachapán geothermal field, El Salvador
Aunzo, Z.; Laky, C.; Steingrimsson, B.; Bodvarsson, G.S.; Lippmann, M.J.; Truesdell, A.H.; Escobar, C.; Quintanilla, A.; Cuellar, G.
The lithology and structural features of the Ahuachapán geothermal area and their impact on the movement of cold and hot fluids within the system are described, as well as the development and evaluation of the natural state model of the field. Four major lithologic units are present in Ahuachapán and three major aquifers have been identified; flow patterns and zones of fluid mixing were located on the basis of temperature and geochemical data from wells and surface manifestations. Geologic structures control the heat and fluid recharge and the flow within the reservoir. Modeling studies suggest, in agreement with field data, an overall average transmissivity of 25–35 darcy-meters, and indicate that the system is recharged by waters with temperatures greater than 250°C. The total thermal throughflow for the Ahuachapán reservoir in the unexploited state is estimated to be about 250 MWt.
Geologic characteristics of a portion of the Salton Sea geothermal field
Tewhey, J.D.
The examination of drill cuttings and core samples from the Magmamax Nos. 2 and 3 and Woolsey No. 1 wells indicate that the sequence of sedimentary rocks in the Salton Sea geothermal field from the surface to below 4000 ft can be divided into three categories: cap rock, unaltered reservoir rocks, and hydrothermally altered reservoir rocks. The cap rock extends from the surface to a depth of approximately 1100 ft in all three wells. There is evidence to suggest that the cap rock has undergone self-sealing through time as a result of the circulation of hot brine through the rocks. Essentially unaltered reservoir rocks extend from a depth of 1100 ft to approximately 3000 ft. The mineralogical and textural changes that occur at depth can be attributed to the process of hydrothermal alteration. Alteration has occurred in a chemically open system and the important variables in the alteration scheme have been temperature, permeability, brine composition, and rock composition. The transition from unaltered to altered reservoir rocks is marked by the replacement of calcite by epidote. The first appearance of epidote correlates reasonably well with the top of the alteration zone as determined in other studies by electric log analysis. Biotite and chlorite, potential indicators of alteration zones, are considered to be of detrital origin rather than hydrothermal origin. The primary effect of hydrothermal alteration on the reservoir rocks in the Salton Sea geothermal field has been the reduction of porosity and permeability with depth. Petrographic analysis indicates that porosity and permeability in the field is enhanced by the presence of fractures in shales. The geologic picture that emerges from spontaneous potential (SP) log correlation is that of a structural basin whose axis lies to the northwest of Magmamax No. 2. The data suggest that unaltered reservoir rocks on the periphery of the field offer good production possibilities.
Hydrothermal Alteration in Submarine Basaltic Rocks from the Reykjanes Geothermal Field, Iceland. (Invited)
Zierenberg, R. A.; Schiffman, P.; Fowler, A. P.; Marks, N.; Fridleifsson, G.; Elders, W. A.
The Iceland Deep Drilling Project (IDDP) is preparing to drill to 4-5 km in the Reykjanes Geothermal Field to sample geothermal fluids at supercritical temperature and pressure for power generation. The Reykjanes geothermal field is the on-land extension of the Reykjanes Ridge spreading center. The upper 1-2 kilometers drilled at Reykjanes are submarine basalts and basaltic sediments, hyalloclastites, and breccias, with an increasing proportion of basaltic intrusive rocks below 2 km depth. Geothermal fluids are evolved seawater with a composition similar to mid-ocean ridge hydrothermal systems. Zn- and Cu-rich sulfide scale, locally enriched in Au and Ag, are deposited in production pipes. The sulfide deposits are compositionally and isotopically similar to seafloor massive sulfides. In anticipation of deeper drilling, we have investigated the mineralogy and geochemistry of drill cuttings from a 3 km deep well (RN-17). The depth zoning of alteration minerals is similar to that described from other Icelandic geothermal fields, and is comparable to observed seafloor metamorphic gradients in ODP drill holes and ophiolites. Chlorite-epidote alteration occurs at depths >400 m and passes downhole through epidote-actinolite alteration and into amphibole facies (hornblende-calcic plagioclase) alteration below 2.5 km. Local zones of high temperature (>800°C), granoblastic-textured, pyroxene hornfels, are interpreted to form by contact metamorphism during dike/sill emplacement. Similar granoblasically altered basalts were recovered from the base of the sheeted dikes in IODP Hole 1256D. Downhole compositional variations of drill cuttings, collected every 50 m, suggest that rocks below ~ 2 km are little altered. Whole-rock oxygen isotope profiles are consistent with low water/rock ratios, but suggest that early stages of hydrothermal alteration included meteoric water-derived fluids. Strontium isotope profiles indicate more extensive exchange with seawater-derived fluids
Full Moment Tensor Analysis Using First Motion Data at The Geysers Geothermal Field
Boyd, O.; Dreger, D. S.; Lai, V. H.; Gritto, R.
Seismicity associated with geothermal energy production at The Geysers Geothermal Field in northern California has been increasing during the last forty years. We investigate source models of over fifty earthquakes with magnitudes ranging from Mw 3.5 up to Mw 4.5. We invert three-component, complete waveform data from broadband stations of the Berkeley Digital Seismic Network, the Northern California Seismic Network and the USA Array deployment (2005-2007) for the complete, six-element moment tensor. Some solutions are double-couple while others have substantial non-double-couple components. To assess the stability and significance of non-double-couple components, we use a suite of diagnostic tools including the F-test, Jackknife test, bootstrap and network sensitivity solution (NSS). The full moment tensor solutions of the studied events tend to plot in the upper half of the Hudson source type diagram where the fundamental source types include +CLVD, +LVD, tensile-crack, DC and explosion. Using the F-test to compare the goodness-of-fit values between the full and deviatoric moment tensor solutions, most of the full moment tensor solutions do not show a statistically significant improvement in fit over the deviatoric solutions. Because a small isotropic component may not significantly improve the fit, we include first motion polarity data to better constrain the full moment tensor solutions.
Estimation of deepwater temperature and hydrogeochemistry of springs in the Takab geothermal field, West Azerbaijan, Iran.
Sharifi, Reza; Moore, Farid; Mohammadi, Zargham; Keshavarzi, Behnam
Chemical analyses of water samples from 19 hot and cold springs are used to characterize Takab geothermal field, west of Iran. The springs are divided into two main groups based on temperature, host rock, total dissolved solids (TDS), and major and minor elements. TDS, electrical conductivity (EC), Cl(-), and SO4 (2-) concentrations of hot springs are all higher than in cold springs. Higher TDS in hot springs probably reflect longer circulation and residence time. The high Si, B, and Sr contents in thermal waters are probably the result of extended water-rock interaction and reflect flow paths and residence time. Binary, ternary, and Giggenbach diagrams were used to understand the deeper mixing conditions and locations of springs in the model system. It is believed that the springs are heated either by mixing of deep geothermal fluid with cold groundwater or low conductive heat flow. Mixing ratios are evaluated using Cl, Na, and B concentrations and a mass balance approach. Calculated quartz and chalcedony geothermometer give lower reservoir temperatures than cation geothermometers. The silica-enthalpy mixing model predicts a subsurface reservoir temperature between 62 and 90 °C. The δ(18)O and δD (δ(2)H) are used to trace and determine the origin and movement of water. Both hot and cold waters plot close to the local meteoric line, indicating local meteoric origin. PMID:26733417
Relocation hypocenter of microearthquake using Markov Chain simulation: Case study on geothermal field
Adu, Nurlia; Indriati Retno, P.; Suharsono
Monitoring of micro seismic activity in the geothermal field is useful to know the fracture controllers in the geothermal reservoir area. However, in determining the point of micro earthquake, hypocenters still contain inherent uncertainties due to several factors such as mismatches velocity model used by the actual subsurface conditions. For that reason, hypocenter relocation by Markov Chain method is used, to simulate the hypocenter point spatially based opportunities transition containing the principle of conditional probability. The purpose of this relocation is to improve the models of the hypocenter so that the interpretation of the subsurface structure is better. From the result of the relocation of using Markov Chain identified fault structures trending below the surface of the northeast-southwest (NE-SW) with approximately N38°E. This structure is suspected as the continuity of the structure in the surface. The depth of the hypocenter is located 758 m above mean sea level more than 800 m below mean sea level.
Reactive geothermal transport simulations to study the formation mechanism of an impermeable barrier between acidic and neutral fluid zones in the Onikobe Geothermal Field, Japan
Todaka, Norifumi; Akasaka, Chitoshi; Xu, Tianfu; Pruess, Karsten
Two types of fluids are encountered in the Onikobe geothermal reservoir (Japan): one is neutral and the other is acidic. It is hypothesized that acidic fluid might be upwelling along a fault zone from magma and that an impermeable barrier might be present between the acidic and neutral fluid zones. To test such a conceptual model and to study the geochemical behavior due to mixing of the two fluids, reactive geothermal transport simulations under both natural and production conditions were carried out using the code TOUGHREACT. Results indicate Mn-rich smectite precipitates near the mixing front. Precipitation of sphalerite and galena occurs in a similar region as the Mn-rich smectite. Precipitation of these minerals depends on pH and temperature. In addition, quartz, pyrite, and calcite precipitate in the shallow zone resulting in further development of caprock. The changes in porosity and permeability due to precipitation of Mn-rich smectite are small compared with that of quartz, calcite, and pyrite. However, the smectite precipitation is likely to fill open fractures and to form an impermeable barrier between acidic and neutral fluid regions. The simulated mineral assemblage is generally consistent with observations in the Onikobe field. The numerical simulations described here provide useful insight into geochemical behavior and formation of impermeable barriers from fluid mixing. The method presented in this paper may be useful in fundamental analysis of hydrothermal systems and in the exploration of geothermal reservoirs, including chemical evolution, mineral alteration, mineral scaling, and changes in porosity and permeability.
Addendum to material selection guidelines for geothermal energy-utilization systems. Part I. Extension of the field experience data base. Part II. Proceedings of the geothermal engineering and materials (GEM) program conference (San Diego, CA, 6-8 October 1982)
Smith, C.S.; Ellis, P.F. II
The extension of the field experience data base includes the following: key corrosive species, updated field experiences, corrosion of secondary loop components or geothermal binary power plants, and suitability of conventional water-source heat pump evaporator materials for geothermal heat pump service. Twenty-four conference papers are included. Three were abstracted previously for EDB. Separate abstracts were prepared for twenty-one. (MHR)
Internal structure of fault zones in geothermal reservoirs: Examples from palaeogeothermal fields and potential host rocks
Leonie Philipp, Sonja; Reyer, Dorothea; Meier, Silke; Bauer, Johanna F.; Afşar, Filiz
Fault zones commonly have great effects on fluid transport in geothermal reservoirs. During fault slip all the pores and small fractures that meet with the slip plane become interconnected so that the inner part of the fault, the fault core, consisting of breccia or gouge, may suddenly develop a very high permeability. This is evidenced, for example by networks of mineral veins in deeply eroded fault zones in palaeogeothermal fields. Inactive faults, however, may have low permeabilities and even act as flow barriers. In natural and man-made geothermal reservoirs, the orientation of fault zones in relation to the current stress field and their internal structure needs be known as accurately as possible. One reason is that the activity of the fault zone depends on its angle to the principal stress directions. Another reason is that the outer part of a fault zone, the damage zone, comprises numerous fractures of various sizes. Here we present field examples of faults, and associated joints and mineral veins, in palaeogeothermal fields, and potential host rocks for man-made geothermal reservoirs, respectively. We studied several localities of different stratigraphies, lithologies and tectonic settings: (1) 58 fault zones in 22 outcrops from Upper Carboniferous to Upper Cretaceous in the Northwest German Basin (siliciclastic, carbonate and volcanic rocks); (2) 16 fault zones in 9 outcrops in Lower Permian to Middle Triassic (mainly sandstone, limestone and granite) in the Upper Rhine Graben; and (3) 74 fault zones in two coastal sections of Upper Triassic and Lower Jurassic age (mudstones and limestone-marl alternations) in the Bristol Channel Basin, UK. (1) and (2) are outcrop analogues of geothermal reservoir horizons, (3) represent palaeogeothermal fields with mineral veins. The field studies in the Northwest German Basin (1) show pronounced differences between normal-fault zones in carbonate and clastic rocks. In carbonate rocks clear damage zones occur that are
Ambient Seismic Noise Monitoring for Stress-Induced Changes in Geysers Geothermal Field, California
Lai, V.; Taira, T.; Dreger, D. S.
The Geysers Geothermal Field in California is one of the most seismically active zones in North America. We investigate the temporal change of the stress field within this region, by analyzing the small perturbations of the velocity structure through the correlations of ambient seismic noise. Vertical component of the continuous record of seismic noise for over 12 months are obtained from an array of seismic stations operated by the Lawrence Berkeley National Laboratory (LBNL). This network contains 30 seismic stations distributed over the entire Geysers geothermal field with an average station distance of 2 to 3 km. This translates into 435 possible combinations of the station pair in which some pairs have overlapping paths that allow us to verify the consistency of the Green's function along the same path. The procedure of the study includes computing hourly cross-correlations of the seismic noise of each station pair and stacking these hourly data into 1-day and subsequently 30-day stacks to obtain a reference Green's function (RGF) with high signal to noise ratio. Overlapping time windows are used to reduce any dependencies or effects of high amplitude transient signals. The relative travel time shift between the RGF and the 30-day stacked correlations in the frequency range from 0.1 to 0.9Hz is measured in which the value obtained is the opposite value of the relative velocity change of the structure. We are particularly interested in detecting temporal changes in seismic velocity structure accompanying tectonic events and fluid injections. To ensure the reliability of our correlations and to account for problematic data, we also perform a synthetic noise analysis by calculating the mean correlation coefficient (R-value) between the reference Green's function and data of varied durations. Correlations, which have an R-value below 0.9, are removed from the analysis.
Hydrogeochemistry of the thermal waters from the Yenice Geothermal Field (Denizli Basin, Southwestern Anatolia, Turkey)
Alçiçek, Hülya; Bülbül, Ali; Alçiçek, Mehmet Cihat
The chemical and isotopic properties of thermal waters (Kamara and Çizmeli) and cold springs from the Yenice Geothermal Field (YGF), in southwestern Anatolia, Turkey are investigated in order to establish a conceptual hydrogeochemical-hydrogeological model. These thermal waters derive from Menderes metamorphic rocks and emerge along normal faults; they are commonly used for heating of greenhouses and bathing facilities. Discharge temperatures of thermal waters are 32 °C to 57 °C (mean 51 °C) for Kamara and 35 °C to 68 °C (mean 47 °C) for Çizmeli, whereas deep groundwaters are 15 °C to 20.1 °C (mean 17 °C) and shallow groundwaters are 12 to 16 °C (mean 15 °C). Kamara and Çizmeli thermal waters are mostly of Na-Ca-HCO3-SO4 type, whereas deep groundwaters are Ca-Mg-HCO3 and Mg-Ca-HCO3 types and shallow groundwaters are mainly Mg-Ca-SO4-HCO3 and Ca-Mg-HCO3 types. In the reservoir of the geothermal system, dissolution of host rock and ion-exchange reactions changes thermal water types. High correlation in some ionic ratios (e.g. Na vs. Cl, K vs. Cl, HCO3 vs. Cl) and high concentrations of some minor elements (e.g., As, Sr, B, Cl, F) in thermal waters likely derive from enhanced water-rock interaction. Water samples from YGF have not reached complete chemical re-equilibrium, possibly as a result mixing with groundwater during upward flow. Geothermal reservoir temperatures are calculated as 89-102 °C for Kamara and 87-102 °C for Çizmeli fields, based on the retrograde and prograde solubilities of anhydrite and chalcedony. Based on the isotope and chemical data, a conceptual hydrogeochemical-hydrogeological model of the YGF has been constructed. Very negative δ18O and δ2H isotopic ratios (Kamara: mean of - 8.43‰ and - 56.9‰, respectively and Çizmeli: mean of - 7.96‰ and - 53.7‰, respectively) and low tritium values (< 1 TU) reflect a deep circulation pathway and a meteoric origin. Subsequent heating by conduction in the high geothermal gradient
Stable isotopes as signposts of fluid throughput in Rotokawa and other geothermal fields, and the difficulty of identifying magmatic fingerprints
We present a background for water-rock interaction generally, and new data on the Rotokawa geothermal field. The oxygen isotope shift of total rock samples allow the deduction of past flowpaths and total fluid throughput. Estimates of any input true exsolved magmatic water are difficult as the lithosphere can act as an effective isotopic screen. (authors). 1 fig., 6 refs
Guidebook to Geothermal Finance
Salmon, J. P.; Meurice, J.; Wobus, N.; Stern, F.; Duaime, M.
This guidebook is intended to facilitate further investment in conventional geothermal projects in the United States. It includes a brief primer on geothermal technology and the most relevant policies related to geothermal project development. The trends in geothermal project finance are the focus of this tool, relying heavily on interviews with leaders in the field of geothermal project finance. Using the information provided, developers and investors may innovate in new ways, developing partnerships that match investors' risk tolerance with the capital requirements of geothermal projects in this dynamic and evolving marketplace.
Pressure changes and their effects on the Cerro Prieto geothermal field
Bermejo M, F.J.; Navarro O, F.X.; Esquer P, C.A.; Castillo B, F.; de la Cruz D, F.C.
Continuous extraction of the water-steam mixture at the field has been increasing to fulfill the steam requirements of the power plant. As a result, pressure declines have been observed in the producing strata in all of the wells, as well as in the geothermal reservoir as a whole. Anomalous behavior that has been observed in the wells' hydraulic columns in most cases is due to the interconnection of the various strata penetrated by the well. When this occurs, unbalanced hydraulic pressures cause the movement of fluids between the strata. As an example of this hydraulic imbalance causing the flow of fluids from an upper to a lower zone, well Nuevo Leon 1 where this effect occurs between regions 600 m apart was chosen.
Reservoir-scale fracture permeability in the Dixie Valley, Nevada, geothermal field
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)
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.
Hydrogeochemical and isotopic characteristics of Kavak (Seydişehir-Konya) geothermal field, Turkey
Bozdağ, Ayla
The Kavak geothermal field is located 13 km north of Seydişehir town, about 90 km southwest of Konya Province in the Central Anatolia, Turkey. This study was carried out to determine the origin, chemical characteristics, and isotopic composition of Kavak thermal waters. The measured temperatures of thermal and mineral waters range from 21.5 to 26 °C with a discharge of 0.8 l/s in springs, and from 30 to 45.8 °C with a discharge of 185 l/s in wells. Thermal and/or mineralized spring and well waters are of Casbnd Nasbnd HCO3 types with electrical conductivity ranging from 2530 to 4150 μS/cm while cold groundwater is mainly of Casbnd HCO3 and Casbnd Mgsbnd HCO3 types with electrical conductivity ranging from 446 to 668 μS/cm. Kavak thermal waters have not reached complete chemical re-equilibrium possibly as a result of mixing with cold water during upward flow. Assessments from quartz geothermometers and fluid-mineral equilibria calculations suggest that reservoir temperature of Kavak geothermal field ranges from 68 to 105 °C. Thermal waters are oversaturated at discharge temperatures for calcite, dolomite, and aragonite minerals corresponding to travertine precipitation in the discharge area. Gypsum and anhydrite minerals are undersaturated in all the thermal waters. The δ18O and δ2H compositions of Kavak thermal and cold waters point to a meteoric origin. Meteoric waters infiltrate the reservoir rocks along faults and fracture zones. After being heated at depth with the high geothermal gradient, they move up to the surface along faults and fractures that act as pathways. Additionally, δ18O and δ2H values suggest that thermal waters are recharged from higher elevations in comparison with cold waters. Long-term circulation of meteoric waters within the basement rocks is indicated by low tritium (<2 TU) values in the thermal waters, although the fluids do not achieve thermodynamic equilibrium. Based on the δ13C values, carbon in thermal waters is considered
Hydrogeochemical and isotopic characteristics of Kavak (Seydişehir-Konya) geothermal field, Turkey
Bozdağ, Ayla
The Kavak geothermal field is located 13 km north of Seydişehir town, about 90 km southwest of Konya Province in the Central Anatolia, Turkey. This study was carried out to determine the origin, chemical characteristics, and isotopic composition of Kavak thermal waters. The measured temperatures of thermal and mineral waters range from 21.5 to 26 °C with a discharge of 0.8 l/s in springs, and from 30 to 45.8 °C with a discharge of 185 l/s in wells. Thermal and/or mineralized spring and well waters are of Casbnd Nasbnd HCO3 types with electrical conductivity ranging from 2530 to 4150 μS/cm while cold groundwater is mainly of Casbnd HCO3 and Casbnd Mgsbnd HCO3 types with electrical conductivity ranging from 446 to 668 μS/cm. Kavak thermal waters have not reached complete chemical re-equilibrium possibly as a result of mixing with cold water during upward flow. Assessments from quartz geothermometers and fluid-mineral equilibria calculations suggest that reservoir temperature of Kavak geothermal field ranges from 68 to 105 °C. Thermal waters are oversaturated at discharge temperatures for calcite, dolomite, and aragonite minerals corresponding to travertine precipitation in the discharge area. Gypsum and anhydrite minerals are undersaturated in all the thermal waters. The δ18O and δ2H compositions of Kavak thermal and cold waters point to a meteoric origin. Meteoric waters infiltrate the reservoir rocks along faults and fracture zones. After being heated at depth with the high geothermal gradient, they move up to the surface along faults and fractures that act as pathways. Additionally, δ18O and δ2H values suggest that thermal waters are recharged from higher elevations in comparison with cold waters. Long-term circulation of meteoric waters within the basement rocks is indicated by low tritium (waters, although the fluids do not achieve thermodynamic equilibrium. Based on the δ13C values, carbon in thermal waters is considered as originating from a mixture
Group II Xenoliths from Lunar Crater Volcanic Field, Central Nevada: Evidence for a Kinked Geotherm
Roden, M.; Mosely, J.; Norris, J.
Group II xenoliths associated with the 140 Ka Easy Chair Crater, Lunar Crater volcanic field, NV, consist of amphibole rich-inclusions including amphibolites, pyroxenites, and gabbros. Abundant minerals in these inclusions are kaersutite, aluminous (7.3-9.7 wt% Al2O3), calcic clinopyroxene, primarily diopside, and olivine (Mg# 69-73) with accessory spinel, sulfide and apatite. Although most apatites are fluor-hydroxyapatite solid solutions, one xenolith contains Cl- and OH-rich apatite suggesting that Cl may have been an important constituent in the parent magma(s) . The xenoliths show abundant evidence for equilibration at relatively low temperatures including amphibole and orthopyroxene exsolution in clinopyroxene, and granules of magnetite in hercynite hosts. If latter texture is due to exsolution, then this particular Group II xenolith equilibrated at temperatures near or below 500oC or at a depth of about 15 km along a conductive geotherm. It may be that all the Group II xenoliths equilibrated at low temperatures given the abundant exsolution textures although Fe-Mg exchange relations suggest equilibration at temperatures in excess of 800oC. Low equilibration temperatures are in conflict with the unusually high equilibration temperatures, >1200oC (Smith, 2000) displayed by Group I xenoliths from this same volcanic field. Taken at face value, the geothermometric results indicate unusually high temperatures in the upper mantle, normal temperatures in the crust and the possibility of a kinked geotherm in the region. Curiously the LCVF lies in an area of "normal" heat flow, south of the Battle Mountain area of high heat flow but the number of heat flow measurements in the Lunar Crater area is very low (Humphreys et al., 2003; Sass, 2005). References: Humphreys et al., 2003, Int. Geol. Rev. 45: 575; Sass et al., 2005, http://pubs.usgs.gov/of/2005/1207/; Smith, 2000, JGR 105: 16769.
A comparison of long-term changes in seismicity at The Geysers, Salton Sea, and Coso geothermal fields
Trugman, Daniel T.; Shearer, Peter M.; Borsa, Adrian A.; Fialko, Yuri
Geothermal energy is an important source of renewable energy, yet its production is known to induce seismicity. Here we analyze seismicity at the three largest geothermal fields in California: The Geysers, Salton Sea, and Coso. We focus on resolving the temporal evolution of seismicity rates, which provides important observational constraints on how geothermal fields respond to natural and anthropogenic loading. We develop an iterative, regularized inversion procedure to partition the observed seismicity rate into two components: (1) the interaction rate due to earthquake-earthquake triggering and (2) the smoothly varying background rate controlled by other time-dependent stresses, including anthropogenic forcing. We apply our methodology to compare long-term changes in seismicity to monthly records of fluid injection and withdrawal. At The Geysers, we find that the background seismicity rate is highly correlated with fluid injection, with the mean rate increasing by approximately 50% and exhibiting strong seasonal fluctuations following construction of the Santa Rosa pipeline in 2003. In contrast, at both Salton Sea and Coso, the background seismicity rate has remained relatively stable since 1990, though both experience short-term rate fluctuations that are not obviously modulated by geothermal plant operation. We also observe significant temporal variations in Gutenberg-Richter b value, earthquake magnitude distribution, and earthquake depth distribution, providing further evidence for the dynamic evolution of stresses within these fields. The differing field-wide responses to fluid injection and withdrawal may reflect differences in in situ reservoir conditions and local tectonics, suggesting that a complex interplay of natural and anthropogenic stressing controls seismicity within California's geothermal fields.
New chemical and original isotopic data on waters from El Tatio geothermal field, Northern Chile
The El Tatio geothermal field is located at an height of 4200-4300 m on the Cordillera de los Andes (Altiplano). Geysers, hot pools and mudpots in the geothermal field and local meteoric waters were sampled in April 2002 and analyzed for major and trace elements, δ2H, δ18O and 3H of water, δ34S and δ18O of dissolved sulfate, δ13C of dissolved total carbonate, and 87Sr/86Sr ratio of aqueous strontium. There are two different types of thermal springs that field, that are chloride-rich water and sulfate-rich water. The chemical composition of chloride springs is controlled by magma degassing and by water-rock interaction processes. Sulfate springs are fed by shallow meteoric water heated by ascending gases. In keeping with the geodynamic setting and nature of the reservoir rocks, chloride water is rich in As, B, Cs, Li; on the other hand, sulfate waste is enriched only in B relative to local meteoric water. Alternatively to a merely meteoric model, chloride waters can be interpreted as admixtures of meteoric and magmatic (circa andesitic) water, which moderately exchanges oxygen isotopes with rocks at a chemical Na/K temperature of about 270degC in the main reservoir, and then undergoes loss of vapor (and eventually mixing with shallow water) and related isotopic effects ascent to the surface. These chloride waters do not present tritium and can be classified as submodern (pre-1952). A chloride content of 5,400 mg/l is estimated in the main reservoir, for which δ2H and δ18O values, respectively of -78 per mille and -6.9 per mille, are calculated applying the multistage-steam separation isotopic effects between liquid and vapor. From these data, the meteoric recharge (Cl≅0 mg/l) of the main reservoir should approach a composition of -107 per mille in δ2H and -14.6 per mille in δ18O, when a magmatic water of δ2H=-20 per mille, δ18O=+10 per mille and Cl=17,500 mg/l is assumed. The 87Sr/86 ratios of the hot springs are quite uniform (0.70876 to 0.70896), with
The structural architecture of the Los Humeros volcanic complex and geothermal field, Trans-Mexican Volcanic Belt, Central Mexico
Norini, Gianluca; Groppelli, Gianluca; Sulpizio, Roberto; Carrasco Núñez, Gerardo; Davila Harris, Pablo
The development of geothermal energy in Mexico is a very important goal, given the presence of a large heat anomaly, associated with the Trans-Mexican Volcanic Belt, the renewability of the resource and the low environmental impact. The Quaternary Los Humeros volcanic complex is an important geothermal target, whose evolution involved at least two caldera events, that alternated with other explosive and effusive activity. The first caldera forming event was the 460 ka eruption that produced the Xaltipan ignimbrite and formed a 15-20 km wide caldera. The second collapse event occurred 100 ka with the formation of the Zaragoza ignimbrite and a nested 8-10 km wide caldera. The whole volcano structure, the style of the collapses and the exact location of the calderas scarps and ring faults are still a matter of debate. The Los Humeros volcano hosts the productive Los Humeros Geothermal Field, with an installed capacity of 40 MW and additional 75 MW power plants under construction. Recent models of the geothermal reservoir predict the existence of at least two reservoirs in the geothermal system, separated by impermeable rock units. Hydraulic connectivity and hydrothermal fluids circulation occurs through faults and fractures, allowing deep steam to ascend while condensate flows descend. As a consequence, the plans for the exploration and exploitation of the geothermal reservoir have been based on the identification of the main channels for the circulation of hydrothermal fluids, constituted by faults, so that the full comprehension of the structural architecture of the caldera is crucial to improve the efficiency and minimize the costs of the geothermal field operation. In this study, we present an analysis of the Los Humeros volcanic complex focused on the Quaternary tectonic and volcanotectonics features, like fault scarps and aligned/elongated monogenetic volcanic centres. Morphostructural analysis and field mapping reveal the geometry, kinematics and dynamics of
Niland development project geothermal loan guaranty: 49-MW (net) power plant and geothermal well field development, Imperial County, California: Environmental assessment
The proposed federal action addressed by this environmental assessment is the authorization of disbursements under a loan guaranteed by the US Department of Energy for the Niland Geothermal Energy Program. The disbursements will partially finance the development of a geothermal well field in the Imperial Valley of California to supply a 25-MW(e) (net) power plant. Phase I of the project is the production of 25 MW(e) (net) of power; the full rate of 49 MW (net) would be achieved during Phase II. The project is located on approximately 1600 acres (648 ha) near the city of Niland in Imperial County, California. Well field development includes the initial drilling of 8 production wells for Phase I, 8 production wells for Phase II, and the possible need for as many as 16 replacement wells over the anticipated 30-year life of the facility. Activities associated with the power plant in addition to operation are excavation and construction of the facility and associated systems (such as cooling towers). Significant environmental impacts, as defined in Council on Environmental Quality regulation 40 CFR Part 1508.27, are not expected to occur as a result of this project. Minor impacts could include the following: local degradation of ambient air quality due to particulate and/or hydrogen sulfide emissions, temporarily increased ambient noise levels due to drilling and construction activities, and increased traffic. Impacts could be significant in the event of a major spill of geothermal fluid, which could contaminate groundwater and surface waters and alter or eliminate nearby habitat. Careful land use planning and engineering design, implementation of mitigation measures for pollution control, and design and implementation of an environmental monitoring program that can provide an early indication of potential problems should ensure that impacts, except for certain accidents, will be minimized.
Isotope and geochemical study of the geothermal fields of Chios Island, Greece
Full text: The study area is located in the west part of Aegean sea, in the Chios Island. Chios is characterised by a strong geothermal activity especially in the area of Aghia Eleni and Agiasmata where the temperature ranges from 26 - 54 deg. C. In the framework of a 1998-2001 bilateral research programme between Italy and Greece, geochemical and isotope investigations were conducted on spring and water wells of Chios in order to improve the knowledge on the geothermal potential of the island. A number of hydrothermal manifestations were found in the northern and southeastern parts of the island, namely in the areas of Nenita-Thimiana, Patrika, Aghia Eleni and Aghiasmata. In the plain of Nenita the outcropping formation is entirely constituted of neogene fluvio-lacustrine deposits which act as the impervious cover of the underlying hydrothermal acquifer. The springs of Aghiasmata issue from the lower-middle Miocene volcanic formations. Groundwater samples from boreholes and springs were collected and analysed for major cations and anions (Cl-, NO3-, SO42-, Na+, K+, Ca2+ and Mg2+), for stable isotopes of water (18O and D), and aqueous sulphate [18O(SO42-) and 34S]. Moreover temperature, conductivity and pH are measured in the field. A study of ionic and isotopic contents shows that thermal springs (Aghia Eleni and Aghiasmata) of Chios Island are fed by seawater. In the case of Aghia Eleni the big marine contribution (89%) disturbs the chemical and isotopic geothermometers. In the case of Aghiasmata the geothermometers suggested equilibrium temperature near 200 deg. C. For the boreholes of the southern part of the island the initial temperature is estimated in the order of 80-90 deg. C. (author)
Assessing Past Fracture Connectivity in Geothermal Reservoirs Using Clumped Isotopes: Proof of Concept in the Blue Mountain Geothermal Field, Nevada USA
Huntington, K. W.; Sumner, K. K.; Camp, E. R.; Cladouhos, T. T.; Uddenberg, M.; Swyer, M.; Garrison, G. H.
Subsurface fluid flow is strongly influenced by faults and fractures, yet the transmissivity of faults and fractures changes through time due to deformation and cement precipitation, making flow paths difficult to predict. Here we assess past fracture connectivity in an active hydrothermal system in the Basin and Range, Nevada, USA, using clumped isotope geochemistry and cold cathodoluminescence (CL) analysis of fracture filling cements from the Blue Mountain geothermal field. Calcite cements were sampled from drill cuttings and two cores at varying distances from faults. CL microscopy of some of the cements shows banding parallel to the fracture walls as well as brecciation, indicating that the cements record variations in the composition and source of fluids that moved through the fractures as they opened episodically. CL microscopy, δ13C and δ18O values were used to screen homogeneous samples for clumped isotope analysis. Clumped isotope thermometry of most samples indicates paleofluid temperatures of around 150°C, with several wells peaking at above 200°C. We suggest that the consistency of these temperatures is related to upwelling of fluids in the convective hydrothermal system, and interpret the similarity of the clumped isotope temperatures to modern geothermal fluid temperatures of ~160-180°C as evidence that average reservoir temperatures have changed little since precipitation of the calcite cements. In contrast, two samples, one of which was associated with fault gauge observed in drill logs, record significantly cooler temperatures of 19 and 73°C and anomalous δ13C and δ18Owater values, which point to fault-controlled pathways for downwelling meteoric fluid. Finally, we interpret correspondence of paleofluid temperatures and δ18Owater values constrained by clumped isotope thermometry of calcite from different wells to suggest past connectivity of fractures among wells within the geothermal field. Results show the ability of clumped isotope
Salton Sea Geothermal Field, California, as a near-field natural analog of a radioactive waste repository in salt
Since high concentrations of radionuclides and high temperatures are not normally encountered in salt domes or beds, finding an exact geologic analog of expected near-field conditions in a mined nuclear waste repository in salt will be difficult. The Salton Sea Geothermal Field, however, provides an opportunity to investigate the migration and retardation of naturally occurring U, Th, Ra, Cs, Sr and other elements in hot brines which have been moving through clay-rich sedimentary rocks for up to 100,000 years. The more than thirty deep wells drilled in this field to produce steam for electrical generation penetrate sedimentary rocks containing concentrated brines where temperatures reach 3650C at only 2 km depth. The brines are primarily Na, K, Ca chlorides with up to 25% of total dissolved solids; they also contain high concentrations of metals such as Fe, Mn, Li, Zn, and Pb. This report describes the geology, geophysics and geochemistry of this system as a prelude to a study of the mobility of naturally occurring radionuclides and radionuclide analogs within it. The aim of this study is to provide data to assist in validating quantitative models of repository behavior and to use in designing and evaluating waste packages and engineered barriers. 128 references, 33 figures, 13 tables
Salton Sea Geothermal Field, California, as a near-field natural analog of a radioactive waste repository in salt
Elders, W.A.; Cohen, L.H.
Since high concentrations of radionuclides and high temperatures are not normally encountered in salt domes or beds, finding an exact geologic analog of expected near-field conditions in a mined nuclear waste repository in salt will be difficult. The Salton Sea Geothermal Field, however, provides an opportunity to investigate the migration and retardation of naturally occurring U, Th, Ra, Cs, Sr and other elements in hot brines which have been moving through clay-rich sedimentary rocks for up to 100,000 years. The more than thirty deep wells drilled in this field to produce steam for electrical generation penetrate sedimentary rocks containing concentrated brines where temperatures reach 365/sup 0/C at only 2 km depth. The brines are primarily Na, K, Ca chlorides with up to 25% of total dissolved solids; they also contain high concentrations of metals such as Fe, Mn, Li, Zn, and Pb. This report describes the geology, geophysics and geochemistry of this system as a prelude to a study of the mobility of naturally occurring radionuclides and radionuclide analogs within it. The aim of this study is to provide data to assist in validating quantitative models of repository behavior and to use in designing and evaluating waste packages and engineered barriers. 128 references, 33 figures, 13 tables.
Review of methods for long term monitoring of the environmental effects of geothermal development (hot spring). part 2. Chinetsu kaihatsu ni kakawaru choki kankyo monitoring donyu chosa. 2 (chikasui onsen(center dot)suishitsukei). ; Data sheet shu
Pertaining to the geothermal development, this is a data sheet collection of domestic and foreign review documentation to establish environmental monitoring system. Global chemistry and physics review comprise examples in Shikano Hot Spring in Tottori Prefecture, deep portion in Shimosuwa region, etc. Hydrologic fluidization study of geothermal water system explained Kakkonda, Matsukawa, Sengan region, Asaseishikawa fault, Tateshina highland, Hakone Yumot, Beppu, etc. Apart, simulation is being made by geothermal structure model. As for the content of hot spring water, there are review results from Noboribetsu, Izu/Hakone, Shimabara, Beppu, etc. Relation between the discharge flow rate of hot spring and rainfall quantity comprises examples in Onikobe, Kusatsu, etc. As for the influence of hot spring development, secular statistic is made of the dynamic water level, temperature and quality of hot spring in Aomori, Bunpi, etc. Influence review of power generation plant installation comprises reports from Hatchobaru, Onikobe, Onuma, Mori, etc. Regarding the geothermal development and environmental assessment, study is made of the scenery, water quality, atmospheric pollution, land subsidence, hot spring exhaustion, change in hydrothermal system, etc. Foreign examples were also explained. 121 figs., 14 tabs.
Recover Act. Verification of Geothermal Tracer Methods in Highly Constrained Field Experiments
Becker, Matthew W. [California State University, Long Beach, CA (United States)
The prediction of the geothermal system efficiency is strong linked to the character of the flow system that connects injector and producer wells. If water flow develops channels or "short circuiting" between injection and extraction wells thermal sweep is poor and much of the reservoir is left untapped. The purpose of this project was to understand how channelized flow develops in fracture geothermal reservoirs and how it can be measured in the field. We explored two methods of assessing channelization: hydraulic connectivity tests and tracer tests. These methods were tested at a field site using two verification methods: ground penetrating radar (GPR) images of saline tracer and heat transfer measurements using distributed temperature sensing (DTS). The field site for these studies was the Altona Flat Fractured Rock Research Site located in northeastern New York State. Altona Flat Rock is an experimental site considered a geologic analog for some geothermal reservoirs given its low matrix porosity. Because soil overburden is thin, it provided unique access to saturated bedrock fractures and the ability image using GPR which does not effectively penetrate most soils. Five boreholes were drilled in a "five spot" pattern covering 100 m2 and hydraulically isolated in a single bedding plane fracture. This simple system allowed a complete characterization of the fracture. Nine small diameter boreholes were drilled from the surface to just above the fracture to allow the measurement of heat transfer between the fracture and the rock matrix. The focus of the hydraulic investigation was periodic hydraulic testing. In such tests, rather than pumping or injection in a well at a constant rate, flow is varied to produce an oscillating pressure signal. This pressure signal is sensed in other wells and the attenuation and phase lag between the source and receptor is an indication of hydraulic connection. We found that these tests were much more effective than constant
Geothermal Resources in Spain; Recurssos geothermicos en Espana
Garcia de la Noceda Marquez, C.
A general view on the geothermal resources is presented and the basic concepts of geothermal fields and their classification, the different possibilities of geothermal energy utilization as well as a general panoramic of geothermal energy in Spain. (Author) 6 refs.
Hydrochemical and isotopic studies in Aksaray geothermal fields central Anatolia, Turkey
The studied area is located at eastern part of Aksaray province in Central Anatolia. The basement rocks of studied area is Paleozoic aged Bozcaldag formation composed of marble, schist and gneiss and Cretaseous aged granitoid intrusion intrude within these basement rocks. These rock units are overlain uncomfortably by middle miocene to Quaternary aged volcanic rocks of Cappadocian volcanic belt interlayer sediments. The compositions of these units are mainly represented by tuff, ignimbrite, reworked tuff interlayer sediments, basalt lavas, ash fall deposits, pumice and dasite to rhyodasitic lava domes.The study area contains Ziga and Acigoel (Narkoey) thermal area, which they have similar geologic environments with in the Cappadocian volcanic belt of the Tertiary to Quaternary age. Existence of surface manifestation like that high regional heat flow, the presence of expanding acidic to weakly acidic hydrothermal alteration surrounding the geothermal area, hot springs which have a temperature of 44-65 degrees indicating the important of geothermal possibilities in the area. Water chemistry studies have been carried out on 34 water samples to estimate relation between hot and cold water, calculate reservoir temperature using geothermometre and mixing models, hydrological isotope studies were carried out to on 10 samples to clarify extending of recharging area and travel time from recharging area to discharging area. Water analyses results were assested using some diagram such as Fournier Cl-Entalphy, SiO2-Entalphy, Langelier- Ludwig, Piper, schoeller etc to classify them. Water-rock interaction have been tried to be define on the base of these result.On the base of water chemistry analyses, all of the cold waters are Ca-Mg-HCO3 and CaHCO3 type. the hot waters in Ziga field classified as Na-Cl-HCO3 type and As and B bearing mineralized hot water. Geothermal fluids in Acigoel field, classified as Ca-Na-HCO3-Cl type and B bearing mineralized hot water, and �
Mineralogical and Geochemical Constraints on Arsenic Mobility in a Philippine Geothermal Field
Chelo PASCUA; Tsutomu SATO; Glenn GOLLA
Arsenic is usually associated with sulphide minerals formed in the geothermal environment.However, sulphide minerals are prone to dissolution after contact with meteoric water under surface oxidizing conditions. Secondary precipitates that form from the dissolution of the primary sulfides exert a greater influence on arsenic mobility in the geothermal environment. Fe-hydroxides have very good affinity with dissolved arsenate and are stable under most surface oxidizing conditions. Both amorphous silica directly precipitated from geothermal fluids and possibly a kaolinite alteration can host a small significant amount of arsenic. These silicates are also more stable under a wide range of pH and redox conditions.
Deformation near the Casa Diablo geothermal well field and related processes Long Valley caldera, Eastern California, 1993-2000
Howle, J.F.; Langbein, J.O.; Farrar, C.D.; Wilkinson, S.K.
Regional first-order leveling lines, which extend from Lee Vining, CA, to Tom's Place, CA, have been surveyed periodically since 1957 by the U.S. Geological Survey (USGS), the National Geodetic Survey (NGS), and Caltrans. Two of the regional survey lines, or leveling networks, intersect at the Casa Diablo geothermal well field. These leveling networks, referenced to a distant bench mark (C916) near Lee Vining, provide time-series vertical control data of land-surface deformation that began around 1980. These data are also useful for delineating localized subsidence at Casa Diablo related to reservoir pressure and temperature changes owing to geothermal development that began in 1985. A comparison of differences in bench-mark elevations for five time periods between 1983 and 1997 shows the development and expansion of a subsidence bowl at Casa Diablo. The subsidence coincides spatially with the geothermal well field and temporally with the increased production rates and the deepening of injection wells in 1991, which resulted in an increase in the rate of pressure decline. The subsidence, superimposed on a broad area of uplift, totaled about 310 mm by 1997. The USGS established orthogonal tilt arrays in 1983 to better monitor deformation across the caldera. One tilt array (DBR) was established near what would later become the Casa Diablo geothermal well field. This array responded to magmatic intrusions prior to geothermal development, tilting away from the well field. With the start of geothermal fluid extraction in 1985, tilt at the DBR array reversed direction and began tilting into the well field. In 1991, geothermal power production was increased by a factor of four, and reservoir pressures began a period of steep decline. These changes caused a temporary three-fold increase in the tilt rate. The tilt rate became stable in 1993 and was about 40% lower than that measured in 1991-1992, but still greater than the rates measured during 1985-1990. Data from the
The World geothermal congress took place in the period from 28 May up to 10 June 2000 in Japan. About 2000 men from 43 countries, including specialists in the area of developing geothermal fields, creating and operating geothermal electrical and thermal plants and various systems for the earth heat application, participated in the work of the Congress. It was noted at the Congress, that development of the geothermal power engineering in the world is characterized by the large-scale application of geothermal resources for the electrical energy generation
Differentiating induced and natural seismicity using space-time-magnitude statistics applied to the Coso Geothermal Field
Schoenball, Martin; Davatzes, Nicholas C.; Glen, Jonathan M. G.
A remarkable characteristic of earthquakes is their clustering in time and space, displaying their self-similarity. It remains to be tested if natural and induced earthquakes share the same behavior. The Coso Geothermal Field is one of the most seismically active areas in California and features an abundance of natural seismicity due to active tectonics and a large number of induced earthquakes resulting from geothermal power production since 1987. We study natural and induced earthquakes comparatively in the same tectonic setting at the Coso Geothermal Field. Covering the pre- and co-production periods from 1981 to 2013, we analyze inter-event times, spatial dimension, and frequency-size distributions for natural and induced earthquakes. Individually, these distributions are statistically indistinguishable. Determining the distribution of nearest-neighbor distances in a combined space-time-magnitude metric lets us identify the triggering relationship of an earthquake pair. Nearest-neighbors pairs naturally fall into two populations that categorize it as either clustered (triggered) or background (independent) events. Compared to natural earthquakes, induced earthquakes feature a larger fraction of background seismicity. Furthermore, they contain a population of independent pairs at large magnitude-rescaled times and small magnitude-rescaled distances. Unlike tectonic processes, stress changes by the field operations occur on much smaller time scale and appear strong enough to drive small-scale faults through several seismic cycles. As a result, we record seismicity close to previous hypocenters after a period on the order of a year.
Extension of the Cerro Prieto field and zones in the Mexicali Valley with geothermal possibilities in the future
Fonseca L, H.L.; de la Pena L, A.; Puente C, I.; Diaz C, E.
This study concerns the possible extension of the Cerro Prieto field and identification of other zones in the Mexicali Valley with geothermal development potential by assessing the structural geologic conditions in relation to the regional tectonic framework and the integration of geologic and geophysical surveys carried out at Cerro Prieto. This study is based on data obtained from the wells drilled to date and the available geological and geophysical information. With this information, a geologic model of the field is developed as a general description of the geometry of what might be the geothermal reservoir of the Cerro Prieto field. In areas with geothermal potential within the Mexicali Valley, the location of irrigation wells with anomalous temperatures was taken as a point of departure for subsequent studies. Based on this initial information, gravity and magnetic surveys were made, followed by seismic reflection and refraction surveys and the drilling of 1200-m-deep multiple-use wells. Based on the results of the final integration of these studies with the geology of the region, it is suggested that the following areas should be explored further: east of Cerro Prieto, Tulecheck, Riito, Aeropuerto-Algodones, and San Luis Rio Colorado, Sonora.
Gas geothermometry in selected Icelandic geothermal fields with comparative examples from Kenya
Zhao Ping [Academia Sinica, Beijing, BJ (China). Inst. of Geology; Armannsson, Halldor [Orkustofnun, Reykjavik (Iceland)
Using data from selected geothermal fields in Iceland, several gas geothermometers are applied to calculate reservoir temperatures. Results for well fluids are compared to estimated inflow temperatures. The effects of gases from other sources, e.g. magmatic fluid entering reservoirs, condensation/boiling, loss of components and mixing of different fluids during upflow, are discussed. Those geothermometers that give results reasonably close to the inflow temperatures, and are not constrained by the need to know thermodynamic parameters, are used to estimate subsurface temperatures from fumarole steam composition. It is suggested that geothermometers based on H{sub 2} and H{sub 2}S concentrations are relatively effective. The CO{sub 2}, H{sub 2}S and H2 geothermometers are also evaluated by thermodynamic simulation using plausible mineral buffers. The CO{sub 2} geothermometer generally gives slightly low temperatures for values in the range 100-200{sup o}C. The calibration of the existing H{sub 2}S and H{sub 2} geothermometers needs improvement when reservoir temperatures are higher than 220{sup o}C. The mineral buffer controlling H{sub 2}S in reservoirs seems to be pyrite + magnetite + epidote + prehnite changing into pyrite + pyrrhotite + epidote + prehnite changing into pyrite + pyrrhotite + epidote + prehnite with increasing temperature. (author)
A geological and geophysical appraisal of the Baca geothermal field, Valles Caldera, New Mexico
Wilt, Michael; Vonder Haar, Stephen
The Baca location #1 geothermal field is located in north-central New Mexico within the western half of the Plio-Pleistocene Valles Caldera. Steam and hot water are produced primarily from the northeast-trending Redondo Creek graben, where downhole temperatures exceed 260°C at depths of less than 2 km. Stratigraphically the reservoir region can be described as a five-layer sequence that includes Tertiary and Quaternary volcanic rocks, and Mesozoic and Tertiary sediments overlying Precambrian granitic basement. Production is mainly controlled by fractures and faults that are ultimately related to activity in the Rio Grande Rift system. Geophysically, the caldera is characterized by a gravity minimum and a resistivity low in its western half. A 40-mgal gravity minimum over the caldera is due mostly to the relatively low-density volcanics and sediments that fill the caldera and probably bears no relation to deep-seated magmatic sources. Two-dimensional gravity modeling indicates that the depth to Precambrian basement in Redondo Canyon is probably at least 3 km and may exceed 5 km in eastern parts of the caldera. Telluric and magnetotelluric surveys have shown that the reservoir region is associated with low resistivity and that a deep low-resistivity zone correlates well with the depth of the primary reservoir inferred from well data. Telluric and magnetotelluric data have also identified possible fault zones in the eastern and western sections of the production region that may form boundaries to the Redondo Creek reservoir. These data also suggest that the reservoir region is located at the intersection of lineaments that trend north-south and northeast-southwest. Magnetotelluric results indicate deep low resistivity at the western edge of the caldera which may be associated with deep hot fluids. On the basis of geophysical and well data, we make three estimates of reservoir dimensions. The estimates of the areal extent of the reservoir range from 10 to 30 km 2
Modelling the Interaction of Multiple Borehole Heat Exchangers in Shallow Geothermal Fields
Shao, H.; Schelenz, S.; Kist, N.; Shim, B. O.; Bucher, A.; Kolditz, O.
The utilization of Borehole Heat Exchanger (BHE) to transfer heat from the shallow subsurface has been a common practice for the Ground Source Heat Pump (GSHP) system. To represent realistic application scenarios for numerical simulations of such systems, saturated and unsaturated conditions as well as heterogeneous soil properties have to be considered. Analytical solutions such as the Moving Finite Line Source (MFLS) model are not flexible enough to capture the full dynamics of the system. Furthermore, application examples with a high density of installed BHEs exist. There, temperature plumes produced by the individual BHEs may start to interact with each other and lead to lower thermal output. To simulate this interaction, a dual continuum approach has been implemented into the open-source FEM simulator OpenGeoSys (OGS). The model is capable of simulating the temperature evolution around the BHE, with the consideration of both saturated and unsaturated groundwater flow processes in the surrounding soil. Instead of imposing Dirichlet or Neumann type of boundary condition at the location of a BHE, the newly developed model allows the user to specify inflow refrigerant temperature and flow rate as the driving force of heat transport. In a benchmark with homogeneous soil properties and fully saturated condition, temperature evolution predicted by the numerical model has been verified against MFLS analytical solution. In a second benchmark, the model simulated outflow temperature is validated by comparing to field measured data from a Thermal Response Test (TRT), provided by the Korean Institute of Geoscience and Mineral Resources (KIGAM) in Dajeon, South Korea. After simulating several shallow geothermal scenarios of multiple BHEs operating in close vicinity, we find that the super-imposed MFLS based analytical solution predicts similar temperature distribution, provided the heat extraction from each BHE is relatively low. However, when the heat exchange rate is
Fracture development within a stratovolcano: The Karaha-Telaga Bodas geothermal field, Java volcanic arc
Nemcok, M.; Moore, J.N.; Allis, R.; McCulloch, J.
Karaha-Telaga Bodas, a vapour-dominated geothermal system located in an active volcano in western Java, is penetrated by more than two dozen deep geothermal wells reaching depths of 3 km. Detailed paragenetic and fluid-inclusion studies from over 1000 natural fractures define the liquid-dominated, transitional and vapour-dominated stages in the evolution of this system. The liquid-dominated stage was initiated by ashallow magma intrusion into the base of the volcanic cone. Lava and pyroclastic flows capped a geothermal system. The uppermost andesite flows were only weakly fractured due to the insulating effect of the intervening altered pyroclastics, which absorbed the deformation. Shear and tensile fractures that developed were filled with carbonates at shallow depths, and by quartz, epidote and actinolite at depths and temperatures over 1 km and 300??C. The system underwent numerous cycles of overpressuring, documented by subhorizontal tensile fractures, anastomosing tensile fracture patterns and implosion breccias. The development of the liquidsystem was interrupted by a catastrophic drop in fluid pressures. As the fluids boiled in response to this pressure drop, chalcedony and quartz were selectively deposited in fractures that had the largest apertures and steep dips. The orientations of these fractures indicate that the escaping overpressured fluids used the shortest possible paths to the surface. Vapour-dominated conditions were initiated at this time within a vertical chimney overlying the still hot intrusion. As pressures declined, these conditions spread outward to form the marginal vapour-dominated region encountered in the drill holes. Downward migration of the chimney, accompanied by growth of the marginal vapour-dominated regime, occurred as the intrusion cooled and the brittle-ductile transition migrated to greater depths. As the liquids boiled off, condensate that formed at the top of the vapour-dominated zone percolated downward and low
Hyperspectral image analysis for the determination of alteration minerals in geothermal fields: Çürüksu (Denizli) Graben, Turkey
Uygur, Merve; Karaman, Muhittin; Kumral, Mustafa
Çürüksu (Denizli) Graben hosts various geothermal fields such as Kızıldere, Yenice, Gerali, Karahayıt, and Tekkehamam. Neotectonic activities, which are caused by extensional tectonism, and deep circulation in sub-volcanic intrusions are heat sources of hydrothermal solutions. The temperature of hydrothermal solutions is between 53 and 260 degree Celsius. Phyllic, argillic, silicic, and carbonatization alterations and various hydrothermal minerals have been identified in various research studies of these areas. Surfaced hydrothermal alteration minerals are one set of potential indicators of geothermal resources. Developing the exploration tools to define the surface indicators of geothermal fields can assist in the recognition of geothermal resources. Thermal and hyperspectral imaging and analysis can be used for defining the surface indicators of geothermal fields. This study tests the hypothesis that hyperspectral image analysis based on EO-1 Hyperion images can be used for the delineation and definition of surfaced hydrothermal alteration in geothermal fields. Hyperspectral image analyses were applied to images covering the geothermal fields whose alteration characteristic are known. To reduce data dimensionality and identify spectral endmembers, Kruse's multi-step process was applied to atmospherically and geometrically-corrected hyperspectral images. Minimum Noise Fraction was used to reduce the spectral dimensions and isolate noise in the images. Extreme pixels were identified from high order MNF bands using the Pixel Purity Index. n-Dimensional Visualization was utilized for unique pixel identification. Spectral similarities between pixel spectral signatures and known endmember spectrum (USGS Spectral Library) were compared with Spectral Angle Mapper Classification. EO-1 Hyperion hyperspectral images and hyperspectral analysis are sensitive to hydrothermal alteration minerals, as their diagnostic spectral signatures span the visible and shortwave
Determination of Microbial Diversity and Nitrogen Cycling from Kizildere Geothermal Field with Next Generation Sequencing
Gulecal, Y.; Dilek, Y.
The deep terrestrial subsurface biosphere represents an emerging frontier for studies of biodiversity, the physiological limits to life, microbial mechanisms of adaptation, and potentially analogous environments for extraterrestrial life (1). Last decade, researches of deep boreholes in the United States, Finland, Sweden, Japan and South Africa, using molecular tools, have shown an an active biosphere composed of diverse groups of microorganisms. The microbial communities reported from different subsurface communities vary widely; such differences are due to different host rock types and varied water origins and chemistry, as well as geography. Furthermore, nitrogen cycling is studied intensely in hot springs for instance in situ nifH expression in Yellowstone National Park, is a new upper temperature limit for nitrogen fixation in alkaline, terrestrial hydrothermal environments (2). This study explores the genetic diversity of microbial communities and genes of nitrogen cycling in Kizildere Geothermal Field, Turkey. The Kizildere thermal waters are located in the northern part of the Büyük Menderes rift zone. The hydrothermal alteration includes phyllic, argillic, silicic,hematitized, and carbonatized alteration zones. The surface temperatures of Kizildere thermal waters in drill holes range from 95 to100°C and pH 9.0-9.5. Microbial communities were examined using culture independent methods, next generation sequencing. Nitrogen fixation, the diversity of nifH, ammonia oxidation (amoA), narG, nosZ genes are investigated in deeply-sourced fluids. We present field observations and interpret new data, establishing a geobiological baseline for previously undescribed sitres of subsurface ecosystems. (1)Fredrickson et al. 2006. Geomicrobial processes and biodiversity in the deep terrestrial subsurface. Geomicrobiology J. 23:345-356. (2) Loiacono et al. 2012. Evidence for high-temperature in situ nifH transcription in an alkaline hot spring of Lower Geyser Basin
Simulation studies for wells AH-4bis/AH-17 and AH-18, Ahuachapan Geothermal Field
Monterrosa, Manuel Ernesto
Well AH-4bis, at the Ahuachapan Geothermal Field is planned to be drilled on the same pad as the former AH-4. A simulation study was carried out for two casing dameters 13 5/8 and 9 5/8" in order to estimate its production and to know its economic feasibility. The simulation results indcate a high probability of production in the range of 7 Mwe, equivalent to 120 kg/s total mass flow rate, 1250 kJ/kg at 6 bar-a for the new well AH-4bis. Well AH- 17 is good producer, during 1991 after ten years of production, the well was shut-in due to silica scaling problems. A wellbore simulation was carried out in order to predict the new production conditions after the work-over, mainly to estimate the water flow rate in order to reduce the silica scaling. The results indicate a very low water flow rate. The match between the simulated and measured production curves after the work-over was successful. The well AH-18 is located at the southern part of the actual bore field. CEL is planning to expand the borefield at this area and it is neccessary to estimate the possible production condtions at that zone. The results indicate a high probabilty of production at that area. The power potential is estimated at 3.5 Mwe per well at WHP 6 bar-a and the wells will not require induction.
The sulphur springs geothermal field, St. Lucia, lesser Antilles: Hydrothermal mineralogy of wells SL-1 and SL-2
Battaglia, S.; Gianelli, G.; Rossi, R.; Cavarretta, G.
Two wells have been drilled to depths of 1413 and 2213 meters in the geothermal field of Sulphur Springs, St. Lucia, and reveal a complex volcanic sequence characterized by collapse episodes followed by the emplacement of dacite domes. The geothermal reservoir consists of fractured volcanic rocks and produces superheated steam. Well-bottom temperatures are around 270-290°C. The hydrothermal alteration found in both the productive SL-2 well and the non-productive SL-1 is strongly reminiscent of that of porphyry copper deposits, with (1) an inner, high-temperature potassic zone characterized by the occurrence of dravitic tourmaline, quartz, and biotite, (2) an outer propylitic alteration zone that is partly superimposed on (3) a potassic alteration zone. The alteration mineral assemblages indicate that the hydrothermal system has cooled at the levels sampled.
The potential of geothermal energy utilization in Jordan was discussed. The report gave a summary of the location of geothermal anomalies in Jordan, and of ongoing projects that utilize geothermal energy for greenhouse heating, fish farming, refrigeration by absorption, and water desalination of deep aquifers. The problems facing the utilization of geothermal energy in Jordan were identified to be financial (i.e. insufficient allocation of local funding, and difficulty in getting foreign financing), and inadequate expertise in the field of geothermal energy applications. The report gave a historical account of geothermal energy utilization activities in Jordan, including cooperation activities with international organizations and foreign countries. A total of 19 reports already prepared in the areas of geochemical and hydrological studies were identified. The report concluded that the utilization of geothermal energy offers some interesting economic possibilities. (A.M.H.). 4 refs. 1 map
Investigation of geothermal fields in himalayan range in pakistan using isotope and chemical techniques
There are many geothermal sites in Himalayan belt of Pakistan having low to high temperatures(boiling water). Isotopes and geochemical techniques were applied to investigate the origin, subsurface history and reservoir temperatures of geothermal fields at Tatta Pani and Tato lying along Main Mantle Thrust, Murtazabad along Main Karakoram Thrust and Kotli in the area of overlapping thrusts: Punjal Thrust, Main Boundary Thrust and the Himalaya Frontal Thrust. Discharge of the springs varies from 30 to 2000 liters per minute with the surface temperature from 47.3 to 92 degree C. Two sets of water samples were collected from these fields. The samples were analyzed for various isotopes (O/sup 18/, H/sup 2/ and H/sup 3/ of water; C/sup 13/ of dissolved inorganic carbon; S/sup 34/ and O/sup 18/ of dissolved sulphates); and water chemistry. The thermal waters of the Northern Areas of Pakistan are generally neutral to slightly alkaline and have low dissolved contents. Sodium is the dominant cation in all the cases. In terms of anions, HCO/sub 3/ is dominating. Source of recharge is meteoric water (rains and/or snow-melt). The dominant process of cooling is conduction at Tatta Pani, Tato, and Murtazabad. Shallow groundwater is mixing with the thermal springs in different proportions at Murtazabad, while there is no mixing in the thermal waters of Tatta Pani and Tato. The equilibrium temperature of the thermal end-member at Murtazabad is in the range of 185- 225 degree C and the isochemical-mixing model based on the Na-K and quartz geothermometers estimates 227 degree C temperature. O/sup 18/ (SO/sub 4/-H/sub 2/O) geothermometer indicates equilibrium temperatures (before mixing) above I85 degree C. The dissolved silica vs. enthalpy plot suggests heat losses through conduction from the original temperature about 245 degree C. The reservoir temperatures of Tatta Pani (100-130 degree C) determined by the Na-K, K-Mg and quartz geothermometers are in good agreement. O/sup 18/ (SO
BULUT, Metin
There are also geothermal areas of low and medium enthalpy besides the high-temperature geothermal fields in the Western Anatolia. These areas are important for thermal tourism and agricultural applications. According to the surface temperature at by the lowtemperature action for known fluid high temperature fluid can be provided. They are the purpose of the study. The study area between the towns of Mendere and Seferihisar. These districts are located south-southwest of Izmir. İnvestigate th...
广东英德市碳酸盐岩地热田地温场特征和成因%Geotherm Characteristics and Genesis of a Carbonatite Geothermal Field in Yingde, Guangdong Province
The Hengshitang geothermal field, located in Yingde, Guangdong Province, is of carbonatite geothermal resources. Based on the regional geological data and the groundwater temperatures collected from the drilling holes, this paper analyses its geotherm characteristics, reservoir conditions, recharge, runoff, and drainage. Devonian-carboniferous carbonatites mainly compose geothermal reservoir of the field, whose geothermal water runoff and geotherm characteristics are controlled by a series of geological structures along Wuchuan-Sihui deep fault zone. Geotemperature curves show that the geothermal field appears an irregular long elliptic shape, with major axis being nearly NW trending, hence inferring that variation of the geotherm is related to fractures and corrosion degree of rocks. There is no additional heat source here, thus the geothermal water is mainly caused by deep cycling process.%广东省英德市横石塘地区的地热田属于碳酸盐岩型地热资源。文章根据钻孔测温资料,结合区域地质资料,分析了该地热田的地温场特征、埋藏条件、补径排条件等。该地热田主要热储层为泥盆―石炭系碳酸盐岩,热水径流特征和地温场特征受吴川―四会深断裂带的一系列构造控制。测温曲线显示:地温场形态呈不规则长椭圆形,长轴方向近北西向,可以推断地温场变化与岩石的断裂、裂隙和溶蚀程度有关。本区无附加型热源,深循环为该区热水的主要形成原因。
Geothermal field and its relation with coalbed methane distribution of the Qinshui Basin
SUN Zhanxue; ZHANG Wen; HU Baoqun; LI Wenjuan; PAN Tianyou
The average geothermal gradient in the Qinshui Basin, Shanxi Province, North China, estimated from temperature logging data of 20 boreholes is 28.2±1.03℃/km.The thermal conductivities of 39 rock samples are measured and 20 heat flow values are obtained. The estimated heat flow ranges from 44.75 mW/m2 to 101.81 mW/m2, with a mean of 62.69±15.20 mW/m2. The thermal history reconstruction from the inversion of vitrinite data, using Thermodel for Windows 2004, reveals that the average paleo-heat flow at the time of maximum burial in late Jurassic to early Cretaceous is 158.41 mW/m2 for the north part, 119.57mW/m2 for the central part and 169.43 mW/m2 for the south part of the basin respectively. The reconstruction of the buried history of the strata indicates that the age for the end of sedimentation and the beginning of erosion for the basin is 108-156 Ma, and that the eroded thickness of the strata is 2603 m in the north, 2291 m in the central, and 2528.9 m in the south of the basin respectively. The "higher in the north and the south, lower in the central" distribution pattern of the paleo-heat flow coincides with the distribution of the coal-bed methane spatially and temporally, which shows that the coal-bed methane is controlled by the paleo-geotemperature field in the basin.
Gas Geothermometry in the Hveragerdi High—Temperature Geothermal Field,SW Iceland
Five gas geothermometers based on the concentrations of CO2,H2S,H2,CH2,N2 and Ar in fumaroles and wet-stem wells are applied to estimating subsurface temperatures in the Hveragerdi high-temperature geothmal field,SW Iceland,The results for fumaroles indicate that the calculated subsurface temperatures decrase from the northern part to the southern part of the field.The CO2-geothermometer gives the highers temperature values,with an average of 256℃ for the northern part,and 247℃ for the southern part.The H2S-geothermometer reveals an aquifer temperature of 211℃ for the northern part,and 203℃ for the southern part.The H2-geothermometer gives an average subsurface temperature of 229℃ for the northern part,and 184℃ for the southern part,which agerees excellently with the measured temperatures in wet-steam wells.The measured borhole temperatures in the field range from 215℃ to 230℃ for the northern part,and from 167℃ to 198℃ for the southern part.The CO2/H2-geothermometer gives the lowest subsurface temperature values,with an average of 203℃ for the northern part,and 143℃ for the southern part,The CO2/N2-geothermometer gives 249℃ for the northern part and 235℃ for the southern part.For the data from wells,the CO2-, H2S-,and H2-geothermometers,give average subsurface temperatures of 247℃ for the northern part and 246℃ for the southern part,213℃ for the northern part and 220℃ for the southern part,and 217℃ for the northern part and 216℃ for the southern part,respectively.The CO2/H2-geothermometer indicates an average subsurface tem,perature of about 200℃ for both the northern part and the southern part.The CO2/N2-geothermometer gives an average subsurface temperature of 180℃ for the northern part and 259℃ for the southern part.The discrepancy between the estimeated subsurface temperatures obtained by the various gas geothermometers has been explained in this paper.By integrating the solute geothermometric results,mixing model
Helium isotopic fingerprints of the heavy land subsidence left in groundwater of the Saga Plain, near Beppu-Shimabara graben, Kyushu, Japan
The Saga Plain is near Beppu-Shimabara graben, a region of potential active volcanism. In the graben, mantle He, which has a high 3He/4He ratio of 1.1 x 10-5, escapes easily from the underlying subduction zone. In groundwater of the Saga Plain, except in the Shiroishi district, this ratio gradually increased as the dissolved He content increased, to a maximum of 5 x 10-6. In central Shiroishi, however, the ratio reached a minimum of 8.7 x 10-7 with increasing dissolved He content, suggesting that groundwater in central Shiroishi has selectively accumulated radiogenic He, which has a very low ratio of 1 x 10-8, rather than reflecting the regional He, which is rich in mantle He. This can be explained if groundwater in Shiroishi has become mixed with fossil pore water drawn from impermeable marine clay aquitard layers. The withdrawal of pore water has also caused severe land subsidence in central Shiroishi
Environmental summary document for the Republic Geothermal, Inc. application for a geothermal loan guaranty project: 64 MW well field and 48 MW (net) geothermal power plant
Layton, D.W.; Powers, D.J.; Leitner, P.; Crow, N.B.; Gudiksen, P.H.; Ricker, Y.E.
A comprehensive review and analysis is provided of the environmental consequences of (1) guaranteeing a load for the completion of the 64 MW well field and the 48 MW (net) power plant or (2) denying a guaranteed load that is needed to finish the project. Mitigation measures are discussed. Alternatives and their impacts are compared and some discussion is included on unavoidable adverse impacts. (MHR)
Development of geothermal field following the 2000 eruption of Usu volcano as revealed by ground temperature, resistivity and self-potential variations
T. Mogi
Full Text Available The 2000 eruption of Usu volcano, NE Japan, took place on the foot of the somma, and formed a cryptodome of 65 m high accompanying numerous faults. We made repeated measurements of ground temperature, Self-Potential (SP and electrical resistivity, in order to clarify the mechanism of development of the newly formed geothermal field on the fault zone. Prior to the expansion of the geothermal field, we detected a resistive zone at the center of the geothermal zone and it supposed to evidence that the zone involving dry steam phase had been formed beneath the fault zone. A rapid expansion of the geothermal field followed along the fault zone away from the craters. The place of maximum amplitude of the SP field also migrated following the expansion of the high ground temperature zone. The high resistive part has shrunk as a consequence of the progress of condensation to warm the surroundings. Based on the observations, we delineated the process of the hydrothermal circulation. Considering the topographic effect of the SP field observed on the highly permeable zone in the Usu somma, the potential flow along the slope of the soma was expected to play an important role to promote the rapid expansion of the geothermal field and the migration of the most active part.
Causality between expansion of seismic cloud and maximum magnitude of induced seismicity in geothermal field
Mukuhira, Yusuke; Asanuma, Hiroshi; Ito, Takatoshi; Häring, Markus
Occurrence of induced seismicity with large magnitude is critical environmental issues associated with fluid injection for shale gas/oil extraction, waste water disposal, carbon capture and storage, and engineered geothermal systems (EGS). Studies for prediction of the hazardous seismicity and risk assessment of induced seismicity has been activated recently. Many of these studies are based on the seismological statistics and these models use the information of the occurrence time and event magnitude. We have originally developed physics based model named "possible seismic moment model" to evaluate seismic activity and assess seismic moment which can be ready to release. This model is totally based on microseismic information of occurrence time, hypocenter location and magnitude (seismic moment). This model assumes existence of representative parameter having physical meaning that release-able seismic moment per rock volume (seismic moment density) at given field. Seismic moment density is to be estimated from microseismic distribution and their seismic moment. In addition to this, stimulated rock volume is also inferred by progress of microseismic cloud at given time and this quantity can be interpreted as the rock volume which can release seismic energy due to weakening effect of normal stress by injected fluid. Product of these two parameters (equation (1)) provide possible seismic moment which can be released from current stimulated zone as a model output. Difference between output of this model and observed cumulative seismic moment corresponds the seismic moment which will be released in future, based on current stimulation conditions. This value can be translated into possible maximum magnitude of induced seismicity in future. As this way, possible seismic moment can be used to have feedback to hydraulic stimulation operation in real time as an index which can be interpreted easily and intuitively. Possible seismic moment is defined as equation (1), where D
Gas Geothermometry for Drilhole Fluids from Vapor Dominated and Hot Water Geothermal Fields
D' Amore, Franco; Truesdall, Alfred H.
The compositions of steam from the vapor-dominated geothermal systems of Larderello, Italy and The Geysers, California have been shown by previous investigators to vary with position in the field. The most conspicuous chemical patterns observed in the Larderello and The Geysers vapor-dominated geotherrnal are strong increases or decreases from the center to the edges of constituents carried in the steam. The pattern of these parameters in vapor-dominated systems seem to be controlled mainly by a process of lateral steam movement and condensation. The condensation process, at constant temperature and total pressure increases the partial pressure of CO{sub 2} at the same rate as the gas/steam ratio, strongly affecting the composition of the total gas (including steam). The condensation effect should increase contents of CO{sub 2}, H{sub 2}S, H{sub 2} and CH{sub 4} in the residual steam to about the same degree because their solubilities are similar. However, the general trend observed is almost constant ratios of H{sub 2}S, H{sub 2}, CH{sub 4} to H{sub 2}O as the CO{sub 2}/H{sub 2}O ratio increases in Larderello about 5-6 times from the center to the edges at constant temperature. This means that the H{sub 2}/CO{sub 2}, CH{sub 4}/CO{sub 2}, and H{sub 2}S/CO{sub 2} ratios decrease with increasing CO{sub 2}/H{sub 2}O ratios. Apparently the only rnechanism that can explain this behavior is reaction of these three gases with other gases and with reservoir minerals so that the partial pressures of these gases are buffered by temperature-dependent reactions with water and rock minerals. A system of appropriate equations involving H{sub 2}O, CO{sub 2}, H{sub 2}. CH{sub 4}, H{sub 2}S were set up. The geothermometers have been tested on data from the Italian fields of Larderello, Travale, Bagnore, Piancastagnaio and from The Geysers, U.S.A. The gas geothermometers have been applied t o steam samples from wells FBN and ALR in order to define changes in both well and reservoir
Environmental assessment of proposed geothermal well testing in the Tigre Lagoon Oil Field, Vermilion Parish, Louisiana
An environmental assessment is made of the proposed testing of two geopressured, geothermal aquifers in central coastal Louisiana. On the basis of an analysis of the environmental setting, subsurface characteristics, and the proposed action, potential environmental impacts are determined and evaluated together with potential conflicts with federal, state, and local programs. (LBS )
Conceptual Model Evaluation of the Astor Pass Geothermal Field, Western Nevada
Reeves, D. M.; Parashar, R.; Pohll, G. M.; Cooper, C. A.; Lyles, B. F.; Faulds, J. E.; Siler, D. L.; Louie, J. N.; Ehni, B.; Kratt, C.; Pullammanappallil, S.; Noel, D.
A blind geothermal system, located approximately 90 km north of Reno, NV on the Pyramid Lake Paiute Tribe Reservation, was characterized and evaluated according to a comprehensive investigation, consisting of geophysical and shallow temperature surveys, structural geological analysis, and reservoir characterization techniques. The geothermal reservoir system, located in basalts, basaltic-andesites and rhyolites of the middle Miocene Lower Pyramid sequence, likely originated as the result of intersections between dextral and normal faults creating a localized region of enhanced extension and fracture permeability. Geologic and geophysical interpretations informed the location of two exploration wells. These wells reached down to the underlying granodiorite basement, confirmed fault structures seen in the seismic images, and were used to characterize the reservoir through borehole fracture characterization and a long duration hydraulic reservoir test. High fracture densities (0.7 m average spacing) were encountered in the reservoir rocks, and results from the hydraulic test indicate that the reservoir is well-connected with drawdown responses observed in a shallow water well located approximately 1 km from the pumping well. Borehole spinner log surveys with temperature probes and high resolution DTS measurements indicate that fracture inflows are relatively constant along the open internval of the boreholes with isothermal temperatures ranging between 92 to 95°C along the exploration wells. Analysis of the reservoir drawdown response yields bulk transmissivity values of 4.8×10-4 to 6.7×10-5 m2/s, with fracture transmissivity values ranging between 1.0×10-4 to 7.2×10-7 m2/s. This comprehensive set of data suggests that the Astor Pass geothermal reservoir is a small system with high fracture connectivity and permeability and relatively isothermal temperatures from 100 m to 1,300 m below land surface. A multiphase geothermal model is currently being developed of
Conservation and Renewable Energy Inquiry and Referral Service (DOE), Silver Spring, MD.
An introduction to geothermal energy is provided in this discussion of: (1) how a geothermal reservoir works; (2) how to find geothermal energy; (3) where it is located; (4) electric power generation using geothermal energy; (5) use of geothermal energy as a direct source of heat; (6) geopressured reservoirs; (7) environmental effects; (8)…
Trace element and isotopic chemistry of the surficial hydrothermal waters in the Cerro Prieto, Geothermal Field, Mexico
Valette-Silver, J.N.; Ganje, T.J.; Bradford, G.R.; Coplen, T.
In the Cerro Prieto Geothermal Field, five kinds of surface emissions were discovered in spring, mud pot, geysers, fumarole, and cool pool. The major element composition of the 163 fluid samples collected in 1979, was previously performed. This study was recently completed by a determination of trace element concentrations, deuterium and oxygen isotope ratios. This geochemical analysis shows, as the major elements do, that each type of surficial emission is characterized by its own unique chemistry. Each category of surface emission appears to result from different processes; trace chemistry as well as isotope composition confirm the various origins of the different surface hydrothermal fluids.
Geothermal handbook. Geothermal project, 1976. [Ecological effects of geothermal resources development
The geothermal program of Fish and Wildlife Service, U.S. Dept. of Interior, aims to develop ecologically sound practices for the exploration, development, and management of geothermal resources and the identification of the biological consequences of such development so as to minimize adverse effects on fish and wildlife resources. This handbook provides information about the ecological effects of geothermal resource development. Chapters are included on US geothermal resources; geothermal land leasing; procedures for assessing the effects on fish and game; environmental impact of exploratory and field development operations; and wildlife habitat improvement methods for geothermal development.
Thermal History of the Felsite Unit, Geysers Geothermal Field, From Thermal Modeling of 40Ar/39Ar Incremental Heating Data
T. M. Harrison (U of California); G. B. Dalrymple (Oregon State U); J. B. Hulen (U of Utah); M. A. Lanphere; M. Grove; O. M. Lovera
An Ar-40/Ar-39 and U-Pb study was performed of the Geysers plutonic complex of the Geysers Geothermal Field in California. Sixty-nine ion microprobe spot analyses of zircons from four granite samples from the plutonic complex that underlies the Geysers geothermal field yielded Pb-207/Pb-206 vs. U-238/Pb-206 concordia ages ranging from 1.13 {+-} 0.04 Ma to 1.25 {+-} 0.04 Ma. The U-Pb ages coincide closely with Ar-40/Ar-39 age spectrum plateau and ''terminal'' ages from coexisting K-feldspars and with the eruption ages of overlying volcanic rocks. The data indicate that the granite crystallized at 1.18 Ma and had cooled below 350 C by {approximately}0.9-1.0 Ma. Interpretation of the feldspar Ar-40/Ar-39 age data using multi-diffusion domain theory indicates that post-emplacement rapid cooling was succeeded either by slower cooling from 350-300 C between 1.0 and 0.4 Ma or transitory reheating to 300-350 C at about 0.4-0.6 Ma. Heat flow calculations constrained with K-feldspar thermal histories and the pre sent elevated regional heal flow anomaly demonstrate that appreciable heat input from sources external to the known Geysers plutonic complex is required to maintain the geothermal system. This requirement is satisfied by either a large, underlying, convecting magma chamber (now solidified) emplaced at 1.2 Ma or episodic intrusion of smaller bodies from 1.2-0.6 Ma.
Determination of recharge areas and circulation periods of the Kutahya-Gediz geothermal fields by means of stable isotopes
The Gediz geothermal field is one of the high enthalpy sites. Dwelling of Gediz is planned by the site which today is being used only for thermal tourism. Basement geology is formed of Paleozoic aged gneiss. These are overlain by Upper Paleozoic - Middle Triassic aged schists, Upper Triassic - Maestrichtian aged limestones, serpantinite ultramaphic rocks including blocks, olistolites with silisified and carbonated rocks, Middle to Upper Miocene aged continental sediments and limestones, lagune and river deposits consisting of limestone and marls, intruded by Middle to Upper Pliocene aged basaltic intrusions. Quaterniary aged deposits; alluvials and travertines form the most upper section of the lithology. Along the Hamam River, E - W extwended, with temperatures varying between 57 to 75.5 degreesand mean discharge of 15 l/s, 9 hot springs discharge, in the Gediz (Abide) geothermal field. According to the production wells drilled by MTA (Mineral Research and Exploration General Directorate), the geothermal systems reservoir consists of fractured zones of the Paleozoic aged gneiss and the karstified zones of the Triassic aged limestones, as well as the gravel and sandstone layers of the Middle - Upper Miocene aged sediments. Groundwaters related with the recharge area give Ca - HCO3 type waters. As a result of the chloride evaluations realized, an enrichment has lead to the groundwater flow direction from the recharge area towards the Abide site. Hot waters of the area give Na-SO4-HCO3 type. According to the Tritium contents, the recharge age of the springs located in the investigation site, varies between 5 - 15 TU. This indicates a 5-10 years of age for the groundwaters, which puts them into a modern waters classification. Evaluation of Deuterium gives that the Gediz Thermal wells are recharged from an elevation of 1700 - 1900 m. This corresponds to the mean altitudes of the karstified limestones and schists of the Saphane Mountain
Numerical simulation of electricity generation potential from fractured granite reservoir through a single horizontal well at Yangbajing geothermal field
Development of deep high-temperature heat reservoir at Yangbajing geothermal field has very important significance for capacity expanding and sustaining of the ground power plant. The geological exploration found that there is a fractured granite heat reservoir with an average temperature of 248 °C at depth of 950∼1350 m in well ZK4001 in the north of the geothermal field. In this work, a simplified conceptual model of the 950∼1350 m reservoir is established based on all the existing geological data, and the electricity generation potential from this fractured granite reservoir by geothermal water mining through a single horizontal well is numerically simulated. The results indicate that the single horizontal well system attains an electric power of 3.23∼3.48 MW and an energy efficiency of about 50.00∼17.16 during 20 years under reference conditions. The main parameters that affect the heat extraction and electricity generation are reservoir porosity, permeability and water production rate. Higher porosity or higher permeability or higher water production rate will be favorable for improving the electricity generation performance, under the precondition of not arousing vaporization and precipitation in the liquid water saturated reservoir. - Highlights: • We established a numerical model of single horizontal-well heat mining system. • Desirable electricity production performance can be obtained under suitable conditions. • The system attains an electric power of 3.23∼3.48 MW with an efficiency of about 50∼17.16 during 20 years. • Electric power mainly depends on water production rate, reservoir porosity and permeability. • Higher porosity or higher permeability or higher water production rate is favorable for electricity generation
Results From a Borehole Seismometer Array II: 3-D Mapping of an Active Geothermal Field at the Kilauea Lower Rift Zone
Shalev, E.; Kenedi, C. L.; Malin, P.
The geothermal power plant in Puna, in southeastern Hawaii, is located in a section of the Kilauea Lower East Rift Zone that was resurfaced by lava flows as recently as 1955, 1960, and 1972. In 2006 a seismic array consisting of eight 3-component stations was installed around the geothermal field in Puna. The instrument depths range from 24 to 210 m. The shallower instruments have 2 Hz geophones and the deeper have 4.5 Hz geophones. 3-D tomographic analyses of P-wave velocity, S-wave velocity, and the Vp/Vs ratio show an area of very fast P-wave velocity at the relatively shallow depth of 2.5 km in the southern section of the field. The same area shows moderate S-wave velocity. This high P-wave velocity anomaly at the southern part of the geothermal field may indicate the presence of dense rock material usually found at greater depths.
Objective of this brochure is to present the subject Geothermics and the possible use of geothermal energy to the public. The following aspects will be refered to: -present energy situation -geothermal potential -use of geothermal energy -environemental aspects -economics. In addition, it presents an up-dated overview of geothermal projects funded by the German government, and a list of institutions and companies active in geothermal research and developments. (orig./HP)
Environmental protection at the Los Azufres, Michoacan geothermal field; La proteccion ambiental en el campo geotermico de Los Azufres, Michoacan
Mendoza Rangel, Ernesto; Hernandez Ayala, Cuauhtemoc [Comision Federal de Electricidad, Morelia, Michoacan (Mexico)
Geothermal-electric development is a sustainable activity from an environmental viewpoint, as is proved by the operation and management of the Los Azufres geothermal field. Impacts to soil and vegetation can be prevented and adequately mitigated. Liquid residues can be returned to the reservoir avoiding contaminating surface and ground waters and aquifers; and atmospheric emissions can kept bellow allowable limits. The main environmental technical experiences of Comision Federal de Electricidad (CFE) in this field are presented in this paper. [Spanish] El desarrollo geotermoelectrico es una actividad sustentable desde el punto de vista ambiental, como lo prueba el manejo del campo geotermico de Los Azufres. Los impactos al suelo y a la vegetacion pueden prevenirse y mitigarse con las medidas adecuadas. Los desechos liquidos pueden regresarse al yacimiento sin contaminar cuerpos de agua superficiales o acuiferos someros, y las emisiones a la atmosfera pueden controlarse para mantenerlas dentro de limites permisibles. Se presentan las principales experiencias tecnicas de tipo ambiental obtenidas por la Comision Federal de Electricidad (CFE) en ese campo.
Results From a Borehole Seismometer Array I: Microseismicity at a Productive Geothermal Field, Kilauea Lower East Rift Zone, Puna, Hawaii
Kenedi, C. L.; Shalev, E.; Malin, P.; Kaleikini, M.; Dahl, G.
Borehole seismometer arrays have proven successful in both the exploration and monitoring of geothermal fields. Because the seismometers are located at depth, they are isolated from human noise and record microearthquakes with clearly identifiable seismic phases that can be used for event location. Further analysis of these events can be used to resolve earthquake clouds into identifiable faults. The local fault and dike structures in Puna, in southeastern Hawaii, are of interest both in terms of electricity production and volcanic hazard monitoring. The geothermal power plant at Puna has a 30MW capacity and is built on a section of the Kilauea Lower East Rift Zone where lava flows erupted as recently as 1955. In order to improve seismic monitoring in this area, we installed eight 3-component borehole seismometers. The instrument depths range from 24 to 210 m (80 to 690 ft); the shallower instruments have 2 Hz geophones and the deepest have 4.5 Hz geophones. The seismometers are located at the vertices of two rhombs, 2 km wide x 4 km long and 4 km wide x 8 km long, both centered at the power plant. Since June 2006, we have located >4500 earthquakes; P- and S-wave arrivals were hand picked and events located using Hypoinverse-2000. Most of the earthquakes occurred at depths between 2.5 and 3 km. The large majority of events were M-0.5 to M0.5; the Gutenberg-Richter b-value is 1.4, which is consistent with microearthquake swarms. Frequency analysis indicates a 7-day periodicity; a Schuster diagram confirms increased seismicity on a weekly cycle. The location, depth, and period of the microearthquakes suggest that power plant activity affects local seismicity. Southwest of the geothermal facility, up-rift towards the Kilauea summit, earthquakes were progressively deeper at greater distances. Depths also increased towards the south, which is consistent with the eastern extension of the south-dipping, east-striking Hilina fault system. To the northeast, down-rift of the
Status of geothermal energy in Ethiopia
This paper reports that there are several identified geothermal localities in Ethiopia. Ten geothermal localities have been studied with regional assessments, while three localities have had pre-feasibility studies. In one area, the Aluto-Langano geothermal field, the feasibility studies have been completed. However, the geothermal resources have not been utilized yet except in the traditional baths
Silica phases in sinters and residues from geothermal fields of New Zealand
Rodgers, K. A.; Browne, P. R. L.; Buddle, T. F.; Cook, K. L.; Greatrex, R. A.; Hampton, W. A.; Herdianita, N. R.; Holland, G. R.; Lynne, B. Y.; Martin, R.; Newton, Z.; Pastars, D.; Sannazarro, K. L.; Teece, C. I. A.
Five silica phases are major components of silica sinters, deposited from both near-neutral pH alkali-chloride and acid-sulfate thermal waters, and of silica residues formed at the surface of geothermal fields in New Zealand. In all cases, the initial silica is noncrystalline opal-A deposited commonly as microspheres that possess an underlying nanospherical substructure, upon different substrate templets, including microbes living in hot springs. Deposition may also occur monomerically upon earlier deposited silica. Following microsphere growth through Ostwald ripening, silica remains mobile throughout the postdepositional history of the sinter/residue deposits, resulting in a range of textures. These include the continuing growth of microspheres, the development of secondary microspheres and silica coatings, phase transformations, a reduction in sinter porosity, dissolution features, and late-stage deposition of drusy quartz and opal-A. The sinter mass attempts to achieve thermodynamic equilibrium through stepwise phase transformations (maturation): opal-A crystallises to paracrystalline opal-CT±opal-C, which recrystallises to microcrystalline α-quartz+moganite. No intermediate silica phases are produced, but gradual changes occur among different opal-A or opal-CT/-C phases. The phase maturation produces changes in particle densities, silanol water, and in X-ray powder response of the different silica phases, although the rates of change can be perturbed by heating, weathering, and dissolution of the sinter/residue. The properties of opal-A change little in a sinter/residue mass within the first 10,000 years, but reductions occur in the densities, silanol water, and X-ray scattering bandwidth of older sinters where opal-A can persist for up to 100,000 years. Eventually, opal-A transforms to opal-CT when silanol water is reduced sufficiently for enough -Si-O-Si- linkages to produce a crude diffraction-like X-ray response. The transformation is aided by heat, as
Field tests of corrosion and chemical sensors for geothermal power plants
Robertus, R.J.; Shannon, D.W.; Sullivan, R.G.; Mackey, D.B.; Koski, O.H.; McBarron, F.O.; Duce, J.L.; Pierce, D.D.
This report summarizes approximately two years of continuous monitoring of corrosion (and other variables that affect corrosion) in a 10-megawatt binary cycle geothermal power plant. The project goal was to develop methods for detecting adverse plant conditions soon enough to prevent equipment failures. The instruments tested were: (1) resistance-type corrosion probes; (2) linear polarization corrosion probes; (3) oxidation/reduction potential (ORP) probes for oxygen detection; (4) high-temperature pH electrodes; and (5) electrodeless conductivity cells for gas bubble detection.
The first geothermal power generation in the world was started at Larderello, Italy in 1904. Then, New Zealand succeeded in the geothermal power generating country. These developments were then followed by the United States, Mexico, Japan and the Soviet Union, and at present, about 25 countries are utilizing geothermal power, or investigating geothermal resources.
Reactive geothermal transport simulation to study the formation mechanism of impermeable barrier between acidic and neutral fluid zones in the Onikobe Geothermal Field, Japan
Todaka, Norifumi; Akasaka, Chitosi; Xu, Tianfu; Pruess, Karsten
Two types of fluids are encountered in the Onikobe geothermal reservoir, one is neutral and the other is acidic (pH=3). It is hypothesized that acidic fluid might be upwelling along a fault zone and that an impermeable barrier might be present between the acidic and neutral fluid zones. We carried out reactive geothermal transport simulations using TOUGHREACT (Xu and Pruess, 1998 and 2001) to test such a conceptual model. Mn-rich smectite precipitated near the mixing front and is likely to form an impermeable barrier between regions with acidic and neutral fluids.
Reactive geothermal transport simulation to study the formation mechanism of impermeable barrier between acidic and neutral fluid zones in the Onikobe Geothermal Field, Japan
Todaka, Norifumi; Akasaka, Chitoshi; Xu, Tianfu; Pruess, Karsten
Two types of fluids are encountered in the Onikobe geothermal reservoir, one is neutral and the other is acidic (pH=3). It is hypothesized that acidic fluid might be upwelling along a fault zone and that an impermeable barrier might be present between the acidic and neutral fluid zones. We carried out reactive geothermal transport simulations using TOUGHREACT (Xu and Pruess, 1998 and 2001) to test such a conceptual model. Mn-rich smectite precipitated near the mixing front and is likely...
Geology of the Pavana geothermal area, Departamento de Choluteca, Honduras, Central America: Field report
Eppler, D.B.; Heiken, G.; Wohletz, K.; Flores, W.; Paredes, J.R.; Duffield, W.A.
The Pavana geothermal area is located in southern Honduras near the Gulf of Fonseca. This region is underlain by late Tertiary volcanic rocks. Within ranges near the geothermal manifestations, the rock sequences is characterized by intermediate to mafic laharic breccias and lavas overlain by silicic tuffs and lavas, which are in turn overlain by intermediate to mafic breccias, lavas, and tuffs. The nearest Quaternary volcanoes are about 40 km to the southwest, where the chain of active Central American volcanoes crosses the mouth of the Gulf of Fonseca. Structure of the Pavana area is dominated by generally northwest-trending, southwest-dipping normal faults. This structure is topographically expressed as northwest-trending escarpments that bound blocks of bedrock separated by asymmetric valleys that contain thin alluvial deposits. Thermal waters apparently issue from normal faults and are interpreted as having been heated during deep circulation along fault zones within a regional environment of elevated heat flow. Natural outflow from the main thermal area is about 3000 l/min of 60/sup 0/C water. Geothermometry of the thermal waters suggests a reservoir base temperature of about 150/sup 0/C.
Isotopic and hydrochemical properties of hot and mineralized waters in SW Konya Geothermal Field (Turkey)
The study area is located at southwest part of Konya (Central Anatolia). The basement formation of the area is Caltepe, deposited from Early Cambrian through Middle Cambrian. Seydisehir Formation which is composed of alternating slate, sandstone and metasandstone overlies conformably the overthrown Caltepe Formation and is Upper Cambrian-Lower Ordovician in age. Seydisehir Formation is conformably underlined by Tarasci Limestone, Neogene in age. Alluvium is Quaternary-Present in age. The hot and mineralized waters are located in the study area around Ilicatepe and Kavakkoy village having temperature range between 31 deg. C and 46 deg. C, flow rate between 1.42 and 5.0 L/s and total dissolved solids between 2,218-3,500 mg/L. Aquifers of these waters are the porous limestone and dolomitic limestone of the Caltepe Formation. The travertine cones occur as a result of water activity. The groundwaters are classified according to the AIH standards are Ca, Na, HCO3, and B bearing hot and mineralized water. The oxygen and hydrogen isotope compositions of geothermal waters reveal meteoric origin. They have more negative δ18O and δ2H values and lower 3H contents compared to cold waters. The geothermal water aquifers are recharged from higher altitudes and they are hardly affected by recent precipitations. (author)
Isotopic and hydrochemical properties of hot and mineralized waters in SW Konya geothermal field (Turkey)
The study area is located at southwest part of Konya (Central Anatolia). The basement formation of the area is Caltepe, deposited from Early Cambrian through Middle Cambrian. Seydisehir Formation which is composed of alternating slate, sandstone and metasandstone overlies conformably the overthrown Caltepe Formation and is Upper Cambrian-Lower Ordovician in age. Seydisehir Formation is conformably underlined by Neocene in age Tarasci Limestone. Alluvium is Quaternary-Present in age. The hot and mineralized waters located in the study area around Ilicatepe and Kavakkoy villages have a temperature range between 31 deg. C and 46 deg. C, flow rate between 1.42 and 5 L/s and a total dissolved mineral between 2218-3500 mg/L. Aquifer of these waters are the porous limestone and dolomitic limestone of the Qaltepe formation. The travertine cones occur as a result of water activity. The waters classified according to the AIH standards are Ca, Na, HCO3, and B bearing hot and mineralized water. The oxygen and hydrogen isotope compositions of geothermal waters reveal meteoric origin. They have more negative δ18O and δ2H values, and lower 3H contents compared to cold waters. The geothermal water aquifers are recharged from higher altitudes and are hardly affected by recent precipitations. (author)
Land subsidence in the Cerro Prieto Geothermal Field, 1 Baja California, Mexico, from 1994 to 2005. An integrated analysis of DInSAR, levelingand geological data.
Sarychikhina, O; Glowacka, E; Mellors, R; Vidal, F S
Cerro Prieto is the oldest and largest Mexican geothermal field in operation and has been producing electricity since 1973. The large amount of geothermal fluids extracted to supply steam to the power plants has resulted in considerable deformation in and around the field. The deformation includes land subsidence and related ground fissuring and faulting. These phenomena have produced severe damages to infrastructure such as roads, irrigation canals and other facilities. In this paper, the technique of Differential Synthetic Aperture Radar Interferometry (DInSAR) is applied using C-band ENVISAR ASAR data acquired between 2003 and 2006 to determine the extent and amount of land subsidence in the Mexicali Valley near Cerro Prieto Geothermal Field. The DInSAR results were compared with published data from precise leveling surveys (1994- 1997 and 1997-2006) and detailed geological information in order to improve the understanding of temporal and spatial distributions of anthropogenic subsidence in the Mexicali Valley. The leveling and DInSAR data were modeled to characterize the observed deformation in terms of fluid extraction. The results confirm that the tectonic faults control the spatial extent of the observed subsidence. These faults likely act as groundwater flow barriers for aquifers and reservoirs. The shape of the subsiding area coincides with the Cerro Prieto pull-apart basin. In addition, the spatial pattern of the subsidence as well as changes in rate are highly correlated with the development of the Cerro Prieto Geothermal Field.
Sub-surface geology, petrochemistry and hydrothermal alteration of Wells MW-03, MW-09 and MW-20 from Menengai geothermal field, Kenya
Mgejwa, Ngereja Myabi, 1981-
The Menengai geothermal field is one of the high temperature geothermal systems in Kenya. It is seated within the Great East Africa Rift System in the Central Kenyan Rift Valley and covered by quarternary volcanics. The study wells, MW-03, MW-09 and MW-20, were drilled inside the Menengai caldera, which is characterized by ring faults, the Molo TVA which trends NNW-SSE and the Solai TVA which trends NNE-SSW direction. The volcano formed about 200,000 years ago and the prominent 12 x 8 km cal...
Preliminary study on the characteristics of carbon and oxygen isotopes in the Shiziping geothermal field groundwater in Emei Mountain
Emei Mountain is a well-known scenic tourism spot in China. In order to promote the development of tourist trade, the authors have explored the hydrothermal water in Emei Mountain. At the beginning of 1998, the hydrothermal water was successfully drilled from the Shiziping geothermal field. In the process of prospecting the hydrothermal water, the authors adopted the geochemical method such as carbon and oxygen isotopes. The result indicates that the groundwater of different genetic types has different constitution characteristics of carbon and oxygen isotopes. This provides the important basis for finding out the forming conditions of underground hydrothermal water. So, it is prospective to study the growth characteristics of hydrothermal water with the carbon and oxygen isotopes of HCO3 in groundwater
A study of production/injection data from slim holes and production wells at the Oguni Geothermal Field, Japan
Garg, S.K.; Combs, J.; Abe, M.
Production and injection data from slim holes and large-diameter wells at the Oguni Geothermal Field, Japan, were examined in an effort to establish relationships (1) between productivity of large-diameter wells and slim holes, (2) between injectivity and productivity indices and (3) between productivity index and borehole diameter. The production data from Oguni boreholes imply that the mass production from large-diameter wells may be estimated based on data from slim holes. Test data from both large- and small-diameter boreholes indicate that to first order the productivity and the injectivity indices are equal. Somewhat surprisingly, the productivity index was found to be a strong function of borehole diameter; the cause for this phenomenon is not understood at this time.
Advanced Geothermal Turbodrill
W. C. Maurer
Approximately 50% of the cost of a new geothermal power plant is in the wells that must be drilled. Compared to the majority of oil and gas wells, geothermal wells are more difficult and costly to drill for several reasons. First, most U.S. geothermal resources consist of hot, hard crystalline rock formations which drill much slower than the relatively soft sedimentary formations associated with most oil and gas production. Second, high downhole temperatures can greatly shorten equipment life or preclude the use of some technologies altogether. Third, producing viable levels of electricity from geothermal fields requires the use of large diameter bores and a high degree of fluid communication, both of which increase drilling and completion costs. Optimizing fluid communication often requires creation of a directional well to intersect the best and largest number of fracture capable of producing hot geothermal fluids. Moineau motor stators made with elastomers cannot operate at geothermal temperatures, so they are limited to the upper portion of the hole. To overcome these limitations, Maurer Engineering Inc. (MEI) has developed a turbodrill that does not use elastomers and therefore can operate at geothermal temperatures. This new turbodrill uses a special gear assembly to reduce the output speed, thus allowing a larger range of bit types, especially tri-cone roller bits, which are the bits of choice for drilling hard crystalline formations. The Advanced Geothermal Turbodrill (AGT) represents a significant improvement for drilling geothermal wells and has the potential to significantly reduce drilling costs while increasing production, thereby making geothermal energy less expensive and better able to compete with fossil fuels. The final field test of the AGT will prepare the tool for successful commercialization.
Dynamics of a geothermal field traced by noble gases: Cerro Prieto, Mexico
Mazor, E. (Weizmann Inst. of Science, Rehovot, Israel); Truesdell, A.H.
Noble gases have been measured mass spectrometrically in samples collected during 1977 from producing wells at Cerro Prieto. Positive correlations between concentrations of radiogenic (He, /sup 40/Ar) and atmospheric noble gases (Ne, Ar, and Kr) suggest the following dynamic model: the geothermal fluids originated from meteoric water penetrated to more than 2500 m depth (below the level of first boiling) and mixed with radiogenic helium and argon-40 formed in the aquifer rocks. Subsequently, small amounts of steam were lost by a Raleigh process (0 to 3%) and mixing with shallow cold water occurred (0 to 30%). Noble gases are sensitive tracers of boiling in the initial stages of 0 to 3% steam separation and complement other tracers, such as Cl or temperature, which are effective only beyond this range.
Evaluation of the solute geothermometry of thermal springs and drilled wells of La Primavera (Cerritos Colorados) geothermal field, Mexico: A geochemometrics approach
Pandarinath, Kailasa; Domínguez-Domínguez, Humberto
A detailed study on the solute geothermometry of thermal water (18 springs and 8 drilled wells) of La Primavera geothermal field (LPGF) in Mexico has been carried out by employing a geochemical database compiled from the literature and by applying all the available solute geothermometers. The performance of these geothermometers in predicting the reservoir temperatures has been evaluated by applying a geochemometrics (geochemical and statistical) method. The springs of the LPGF are of bicarbonate type and the majority have attained partial-equilibrium chemical conditions and the remaining have shown non-equilibrium conditions. In the case of geothermal wells, water is dominantly of chloride-type and, among the studied eight geothermal wells, four have shown full-equilibrium chemical conditions and another four have indicated partial-equilibrium conditions. All springs of HCO3- type water have provided unreliable reservoir temperatures, whereas the only one available spring of SO42- type water has provided the reservoir temperature nearer to the average BHT of the wells. Contrary to the general expected behavior, spring water of non-equilibrium and geothermal well water of partial-equilibrium chemical conditions have indicated more reliable reservoir temperatures than those of partially-equilibrated and fully-equilibrated water, respectively. Among the chemical concentration data, Li and SiO2 of two springs, SO42- and Mg of four springs, and HCO3 and Na concentrations of two geothermal wells were identified as outliers and this has been reflected in very low reservoir temperatures predicted by the geothermometers associated with them (Li-Mg, Na-Li, Na-K-Mg, SiO2 etc.). Identification of the outlier data points may be useful in differentiating the chemical characteristics, lithology and the physico-chemical and geological processes at the sample locations of the study area. In general, the solute geothermometry of the spring waters of LPGF indicated a dominantly
The Tianjin geothermal field (north-eastern China): Water chemistry and possible reservoir permeability reduction phenomena
Minissale, Angelo; Montegrossi, Giordano; Orlando, Andrea [Institute of Geosciences and Earth Resources, National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Florence (Italy); Borrini, Daniele; Tassi, Franco [Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Florence (Italy); Vaselli, Orlando [Institute of Geosciences and Earth Resources, National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Florence (Italy); Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Florence (Italy); Huertas, Antonio Delgado [Estacion Experimental de Zaidin (CSIC), Prof. Albareda 1, 18008 Granada (Spain); Yang, Jincheng; Cheng, Wanquing [Aode Renewable Energy Research Institute, 90 Weijin South Road, Nankai District, 300381 Tianjin (China); Tedesco, Dario [Department of Environmental Sciences, Second University of Naples, Via Vivaldi 43, Caserta 81100 (Italy); Institute of Environmental Geology and Geo Engineering (CNR), Piazzale A. Moro 5, Roma 00100 (Italy); Poreda, Robert [Department of Earth and Environmental Sciences, University of Rochester, 227 Hutchison Hall, Rochester, NY 14627 (United States)
Injection of spent (cooled) thermal fluids began in the Tianjin geothermal district, north-eastern China, at the end of the 1990s. Well injectivities declined after 3-4 years because of self-sealing processes that reduced reservoir permeability. The study focuses on the factors that may have caused the observed decrease in permeability, using chemical and isotopic data on fluids (water and gas) and mineral phases collected from production and injection wells. The results of data processing and interpretation indicate that (1) it is very unlikely that calcite and silica precipitation is taking place in the reservoir; (2) the Fe- and Zn-rich mineral phases (e.g. sulfides, hydroxides and silicates) show positive saturation indexes; (3) SEM and XRD analyses of filtered material reveal that the latter mineral phases are common; (4) visual observation of casings and surface installations, and of corrosion products, suggests that a poor quality steel was used in their manufacture; (5) significant quantities of solids (e.g. quartz and feldspar crystals) are carried by the geothermal fluid; (6) seasonal changes in fluid composition lead to a reduction in casing corrosion during the summer. It was concluded that the decrease in injectivity in the Tianjin wells is caused only in part by the oxidation of casings, downhole pumps, and surface installations, triggered by free oxygen in the injected fluids; the utilization of better quality steels should drastically reduce this type of corrosion. Self-sealing of pores and fractures by reservoir formation solids and by the Fe-corrosion products suspended in the injected fluids seems to be a more important phenomenon, whose effect could be greatly reduced by installing filtering devices at all sites. (author)
Seismic activity and stress tensor inversion at Las Tres Vírgenes Volcanic and Geothermal Field (México)
Antayhua-Vera, Yanet; Lermo-Samaniego, Javier; Quintanar-Robles, Luis; Campos-Enríquez, Oscar
We analyze local earthquakes occurring between 2003 and 2012 at the Las Tres Vírgenes Volcanic and Geothermal Field (TVVGF) to establish their temporal and spatial distribution, and relationships with local and regional fault systems, water injection, acid stimulation and steam production tests. We obtained focal mechanisms and inverted data for the stress tensor to understand the local and regional stress fields. We analyzed 423 local earthquakes with magnitudes between 0.1 and 2.9 Mc and hypocentral depths from 0.2 to 7.4 km b.s.l. The cutoff depth at ~ 7.4 km possibly delineates the brittle-ductile transition zone. We identified seven swarms (from 1 to 7). Swarms 1 (December 2009), 2 (May 2010), 3 (June-July 2010) and 7 (December 2012) are strongly correlated with injection processes; whereas swarms 5 (April 2012) and 6 (September 2012) are correlated with local tectonic faults. Stress inversion showed NW-SE, E-W and NE-SW extensional orientations (Shmin), in agreement with the local tectonic stress field; while NE-SW compressional orientations (SHmax) are correlated with the regional tectonic stress field.
<正>20091762 Guo Wancheng(Xining Jiulong Engineering Investigation Ltd.,Xining 810700,China);Shi Xingmei Development and Utilization of Guide Basin's Geothermal Resources of Qinghai Province(Hydrogeology and Engineering Geology,ISSN1000-3665,CN11-2202/P,35(3),2008,p.79-80,92,2 illus.,2 tables,2 refs.)Key words:geothermal resources,QinghaiThis paper introduced the background of geothermal conditions and the many years of geothermal exploration data in Guide Basin.Then,the authors discussed the geothermal resources feature of Guide basin and raised some opinions on the reasonable development and utilization of geothermal resources.
Subsurface geology of Los Humeros geothermal field, Puebla, Mexico; Geologia del subsuelo del campo geotermico de Los Humeros, Puebla, Mexico
Cedillo Rodriguez, Fidel [Comision federal de Electricidad, Perote, Veracruz, Mexico(Mexico)
In the 1980s, most geologists correlated subsurface geology at Los Humeros geothermal field using penetrated by faults, as interpreted by photogeology. These were structural objectives for geothermal drilling programs. Recent petrology reinterpretation of data from well cutting lets us identify nine lithologic units, with the Toba Vitrea Humeros as the index horizon. The study of the subsurface geology allows us to demonstrate- based on the distribution, depth, and thickness of the lithologic units- that the augite andesites, the Toba Vitrea Humeros, the hornblende andesites, the basalt, and the metamorphosed limestone are affected by system of hidden faults (with no surface evidence) replaced by major fracture zones able to contain steam. Thus these hidden faults are the structural objectives controlling design and sitting of new wells. We conclude that the lithologic unit of augite andesites forms the upper geothermal reservoir, and the hornblende andesites and basalt comprise the lower reservoir- separated from each other by the Toba Vitrea Humeros lithologic unit. Based on the subsurface geologic model, we propose drilling 40 new wells, a long and parallel the north-south faults system. [Spanish] En la decada de los 80s se agrupo la geologia del subsuelo de Los Humeros en cuatro unidades litologicas afectadas por fallas interpretadas por fotogeologia. Estas fallas eran el objetivo estructural para programar la perforacion de pozos geotermicos. La reinterpretacion de los datos de petrologia de las muestras de canal permite identificar nueve unidades litologicas, de las cuales la unidad Toba Vietrea Humeros se comporta como horizonte indice. El estudio de la geologia del subsuelo permite demostrar, con base en la distribucion, profundidades y espesores de las unidades litologicas, que las andesitas de augita, la Toba Vitrea Humeros, las andesitas de hornblenda, los basaltos, y las calizasmetamorfizadas estan afectadas por sistemas de fallas ocultas (sin
Using earthquake clusters to identify fracture zones at Puna geothermal field, Hawaii
Lucas, A.; Shalev, E.; Malin, P.; Kenedi, C. L.
The actively producing Puna geothermal system (PGS) is located on the Kilauea East Rift Zone (ERZ), which extends out from the active Kilauea volcano on Hawaii. In the Puna area the rift trend is identified as NE-SW from surface expressions of normal faulting with a corresponding strike; at PGS the surface expression offsets in a left step, but no rift perpendicular faulting is observed. An eight station borehole seismic network has been installed in the area of the geothermal system. Since June 2006, a total of 6162 earthquakes have been located close to or inside the geothermal system. The spread of earthquake locations follows the rift trend, but down rift to the NE of PGS almost no earthquakes are observed. Most earthquakes located within the PGS range between 2-3 km depth. Up rift to the SW of PGS the number of events decreases and the depth range increases to 3-4 km. All initial locations used Hypoinverse71 and showed no trends other than the dominant rift parallel. Double difference relocation of all earthquakes, using both catalog and cross-correlation, identified one large cluster but could not conclusively identify trends within the cluster. A large number of earthquake waveforms showed identifiable shear wave splitting. For five stations out of the six where shear wave splitting was observed, the dominant polarization direction was rift parallel. Two of the five stations also showed a smaller rift perpendicular signal. The sixth station (located close to the area of the rift offset) displayed a N-S polarization, approximately halfway between rift parallel and perpendicular. The shear wave splitting time delays indicate that fracture density is higher at the PGS compared to the surrounding ERZ. Correlation co-efficient clustering with independent P and S wave windows was used to identify clusters based on similar earthquake waveforms. In total, 40 localized clusters containing ten or more events were identified. The largest cluster was located in the
Steele, B.C.; Harman, G.; Pitsenbarger, J. [eds.
Geothermal Energy Technology (GET) announces on a bimonthly basis the current worldwide information available on the technologies required for economic recovery of geothermal energy and its use as direct heat or for electric power production.
A brief article reviews the development of geothermal energy within the OECD countries. Topics covered include power generation, direct use, hot dry rocks and geothermal heat pumps. The limited exploitation in the UK is also described. (UK)
San Ignacio (La Tembladera) geothermal site, Departamento de Francisco Morazan, Honduras, Central America: Geological field report
Aldrich, M.J.; Eppler, D.; Heiken, G.; Flores, W.; Ramos, N.; Ritchie, A.
The San Ignacio (La Tembladera) geothermal site is located on the north side of the Siria Valley, Departamento de Francisco Morazan, near the village of Barrosa. Hot springs are located along a northwest-trending fault scarp at the edge of the valley and along north-trending faults that cross the scarp. The rocks in the area are primarily Paleozoic metamorphic rocks, overlain by patches of Tertiary Padre Miguel Group tuffs and alluvial deposits. Movement probably occurred along several faults during latest Tertiary and possibly early Quaternary times. Four spring areas were mapped. Area 1, the largest, is associated with a sinter mound and consists of 40 spring groups. About half of the springs, aligned along a north-south trend, are boiling. Area 2 is a small sinter mound with several seeps. Area 3 consists of a group of hot and boiling springs aligned along a north-trending fault. The springs rise through fractured schists and a thin cover of alluvium. Area 4 is located at the intersection of several faults and includes one of the largest boiling springs in the area.
Methods for collection and analysis of geopressured geothermal and oil field waters
Lico, M.S.; Kharaka, Y.K.; Carothers, W.W.; Wright, V.A.
Present methods are described for the collection, preservation, and chemical analysis of waters produced from geopressured geothermal and petroleum wells. Detailed procedures for collection include precautions and equipment necessary to ensure that the sample is representative of the water produced. Procedures for sample preservation include filtration, acidification, dilution for silica, methyl isobutyl ketone (MIBK) extraction of aluminum, addition of potassium permanganate to preserve mercury, and precipitation of carbonate species as strontium carbonate for stable carbon isotopes and total dissolved carbonate analysis. Characteristics determined at the well site are sulfide, pH, ammonia, and conductivity. Laboratory procedures are given for the analysis of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, iron, manganese, zinc, lead, aluminum, and mercury by atomic absorption and flame emission spectroscopy. Chloride is determined by silver nitrate titration and fluoride by ion-specific electrode. Bromide and iodide concentrations are determined by the hypochlorite oxidation method. Sulfate is analyzed by titration using barium chloride with thorin indicator after pretreatment with alumina. Boron and silica are determined colorimetrically by the carmine and molybdate-blue methods, respectively. Aliphatic acid anions (C/sub 2/ through C/sub 5/) are determined by gas chromatography after separation and concentration in a chloroform-butanol mixture.
Isotopic and geochemical study of the Domuyo geothermal field, Neuquen, Argentina
Environmental isotopes, 2H, 18O and 3H as well as chemical analyses of dissolved solids and gases have been performed in order to establish a circulation model and reservoir temperature. According to tritium levels and isotope content, recharge occurs 2900 m above sea level on the west slope of the Domo volcano. Water from a geyser, ''El Humazo'', was recognized as the more related to the primary deep geothermal fluid, although with a minor proportion of fresh water. Reservoir temperature as estimates by the Na-K-Ca geothermometer on this manifestation yield a value of 225 deg. C. A shallower reservoir with temperature of about 176 deg. C (Na-K-Ca geothermometer) is evidenced in ''Las Olletas' and ''Los Tachos'' also affected by dilution and steam loss processes. Finally, temperate manifestations as ''Aguas Calientes'' and ''Banos de Aguas Calientes'' are the result of mixing between Las Olletas type waters with fresh meteoric shallower waters. Gas thermometry and computation of fluid and mineral equilibrium yield temperatures between 220-248 deg. C for the deep reservoir, in agreement with more classical techniques and suggest a value near to zero for the vapor fraction (Y) at depth and confirm the liquid state of the fluid into the reservoir. (author). 23 refs, 19 figs, 8 tabs
Manzella A.
Geothermal technologies use renewable energy resources to generate electricity and direct use of heat while producing very low levels of greenhouse-gas (GHG) emissions. Geothermal energy is stored in rocks and in fluids circulating in the underground. Electricity generation usually requires geothermal resources temperatures of over 100°C. For heating, geothermal resources spanning a wider range of temperatures can be used in applications such as space and district heating (and cooling, with p...
Mohl, C.
Several tasks of JPL related to geothermal energy are discussed. The major task is the procurement and test and evaluation of a helical screw drive (wellhead unit). A general review of geothermal energy systems is given. The presentation focuses attention on geothermal reservoirs in California, with graphs and charts to support the discussion. Included are discussions on cost analysis, systems maintenance, and a comparison of geothermal and conventional heating and cooling systems.
Genesis Model of the Tangquan Geothermal Field in Hebei Province%河北遵化汤泉地热田成因模式
李攻科; 王卫星; 杨峰田; 李宏; 沈键; 董路阳
河北遵化汤泉地热资源丰富,阐明其成因模式对于该地热田的进一步开发和热水资源的可持续利用具有一定的指导意义。基于地温测量和水文地球化学分析等方法对其进行了系统研究,结果表明该地热田属中低温对流型地热系统。地热田在其以北的山区接受大气降水补给,补给高程下限约为935 m。地热流体在深循环过程中于正常的大地热流背景下被围岩逐渐加热,热储温度约为130℃,循环深度约为4800 m。在汤泉福泉宫至疗养院一带,构造切割花岗岩体,使得深部地热流体沿破碎带上涌,混合并加热赋存于蓄水构造中的片麻岩裂隙水,形成汤泉地区的地热异常。%Tangquan is located in the northwest of Zunhua city,Hebei Province.The region is of hilly land-scape ,and rich in geothermal resources.It is of great importance to elucidate the genesis mechanism of the geo-thermal field for sustainable development of the geothermal resources.In this paper,we conducted a systematic study to explore into the genesis mechanism through well temperature logging and hydrogeochemical investiga-tion.Results show that the geothermal field belongs to a low to medium temperature geothermal system of con-vective type.The geothermal fluid origins from the rainfall recharged in the mountainous area located to the north of geothermal field,with a recharge elevation of more than 935 m.The geothermal fluid is gradually heat-ed by the surrounding rock under a normal heat flow background during a deep cycling of ca.4,800 m,with a reservoir temperature of ca. 1 30 ℃.In the zone of Fuquan palace to sanatorium in Tangquan area where several faults cut through the monzonitic granite body,the geothermal fluid up flow along the faults and mix with the fis-sure water stored in the gneisses,forming the Tangquan geothermal field.
This chapter discusses the role of geothermal energy may have on the energy future of the US. The topics discussed in the chapter include historical aspects of geothermal energy, the geothermal resource, hydrothermal fluids, electricity production, district heating, process heating, geopressured brines, technology and costs, hot dry rock, magma, and environmental and siting issues
Why the seismicity induced in Soultz-sous-Forêts and Gross Schoenebeck enhanced geothermal fields are so different? (Invited)
Gaucher, E.; Kohl, T.
In enhanced geothermal systems, hydraulic fracturing and hydraulic stimulation are techniques used to increase the reservoir permeability. Their secondary effect, the induced seismicity, is a unique means to image the fault network created or reactivated by the operations. The interpretation of the results for this latter application is however limited by the capabilities of the seismic network and by our understanding of the involved physical processes. Here, we propose to highlight systematic behaviors of the seismicity induced in enhanced geothermal reservoirs. This is performed through the analysis of two EGS sites which appear to behave very differently in terms of induced seismicity: the Soultz-sous-Forêts (France) and the Gross Schoenebeck (Germany) fields. Several physics-based models have been tested for these fields and these observations should be used to calibrate them and the underlying physical assumptions. The Soultz-sous-Forêts (France) geothermal field is located in the Upper Rhine valley. Over the development of this EGS, four wells have been drilled into the granitic basement, up to 5 km depth, and eight major stimulations were carried out to create the heat exchanger. Several major observations based on the large induced seismicity database have been made and can apply on other EGS. Hence, it was noticed that a) the induced seismicity mainly occurs along planar features, b) during stimulation, the induced seismicity becomes stronger over time and this is still observed after shut-in. Most often, the largest magnitude microearthquake occurs following shut-in, c) over a certain overpressure threshold, seismicity can be induced and also a clear Kaiser effect can be observed for already stimulated volumes, d) the stimulation and the circulation periods induce different seismic responses. At Gross Schoenebeck (Germany), the Dethlingen sandstones and the underlying andesitic volcanic rocks of the Rotliegend formation of the North German Basin
Fracture mapping in the Soultz-sous-Forêts geothermal field using microearthquake locations
Michelet, Sophie; ToksöZ, M. Nafi
In 2003, a massive hydraulic fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The 2 week injection of water generated a high level of microseismic activity, triggering about 90,000 microearthquakes during and after the fluid injection. Of these, 21,000 events, detected at all stations, were located individually with a grid search algorithm to characterize the extent of the seismic zones and ultimately of the fracture network. The accuracy of these initial locations was around 70 m, not sufficient to map detailed fracture patterns. A precise relocation effort was undertaken to reduce the location uncertainties using three different techniques: joint hypocenter determination (JHD), collapsing and multiplet analysis. The collapsing method was added to the JHD results to further consolidate the hypocenters. On the other hand, a multiplet analysis was performed on the initial data set for identifying microearthquakes with similar waveforms and hence relocating relatively the correlated events. The delays in traveltime were computed by wavelet analysis and the events were relocated using a grid search algorithm. We found 7463 events whose seismograms correlated with a correlation coefficient of 0.8 or higher, most of which were doublets. Multiplets are horizontal tube-like structures with lengths from a hundred to several hundred meters striking along the direction of the maximum compressive horizontal stress. We interpret these structures as the preferential paths where fluid flow is largely confined. This hypothesis is reinforced by the good correlation in depth between the events and the fluid outflows observed in the well. Therefore we believe that these relocated events highlight the zones where the permeability of the reservoir is increased.
A closely-spaced magnetotelluric study of the Ahuachapan-Chipilapa geothermal field, El Salvador
Romo, Jose Manuel; Flores, Carlos; Vega, Raymundo; Vazquez, Rogelio; Flores, Marco A. Perez; Trevino, Enrique Gomez; Esparza, Francisco J.; Garcia, Victor H. [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Baja California (Mexico); Quijano, Julio E. [Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL), Santa Tecla (El Salvador)
The distribution of electrical conductivity beneath the Ahuachapan-Chipilapa geothermal area was simulated using 2-D models based on 126 closely-spaced magnetotelluric (MT) measurements. The observed MT response was interpreted as being produced by the superposition of two orthogonal geological structural systems: an approximately E-W regional trend associated with the Central Graben structure, which affects the loner period response, and a local and younger N-S fault system that is responsible for the short-to-intermediate period data. The MT response in the 0.02-10 s range period was used to simulate the conductivity structure within the first 2 km depth. By correlating the low-resistivity zones between twelve 2-D models, maps of the spatial distribution of conductors at three different depth levels were constructed. Three deep conductors were identified, one of the associated with the Ahuachapan reservoir, another apparently related to the Laguna Verde volcano, and a third one controlled by El Tortuguero Graben. The subsurface geometry of these conductivity anomalies suggests that the the Chipilapa and La Labor hot springs are supplied by two separate sources of hot fluids, one coming from the east and the other from the south or southwest. The distribution of the shallow high-conductivity zones agrees with the hydrothermal alteration zones mapped at the surface, suggesting that at shallow levels the argillitization process contributes significantly to the low resistivity. The large number of drillholes and the dense MT site coverage allowed the definition of important correlations between high temperatures and high conductivity, as well as between deep conductivity anomalies and productive wells. On this basis two years for future drilling are proposed. (Author)
A study of production/injection data from slim holes and large-diameter wells at the Takigami Geothermal Field, Kyushu, Japan
Garg, S.K. [Maxwell Federal Div., Inc., San Diego, CA (United States); Combs, J. [Geo-Hills Associates, Los Altos Hills, CA (United States); Azawa, Fumio [Idemitsu Kosan Co. Ltd., Tokyo (Japan); Gotoh, Hiroki [Idemitsu Oita Geothermal Co. Ltd., Oita (Japan)
Production and injection data from nine slim holes and sixteen large-diameter wells at the Takigami Geothermal Field, Kyushu, Japan were analyzed in order to establish relationships (1) between injectivity and productivity indices, (2) between productivity/injectivity index and borehole diameter, and (3) between discharge capacity of slim holes and large-diameter wells. Results are compared with those from the Oguni and Sumikawa fields. A numerical simulator (WELBOR) was used to model the available discharge rate from Takigami boreholes. The results of numerical modeling indicate that the flow rate of large-diameter geothermal production wells with liquid feedzones can be predicted using data from slim holes. These results also indicate the importance of proper well design.
Cost model for geothermal wells applied to the Cerro Prieto geothermal field case, BC Abstract; Modelo de costeo de pozos geotermicos aplicado para el caso del campo geotermico de Cerro Prieto, BC
Vaca Serrano, Jaime M.E [Comision Federal de Electricidad, Gerencia de Proyectos Geotermoelectricos, Morelia, Michoacan (Mexico)]. E-mail: email@example.com
A project for drilling geothermal wells to produce electrical energy can be defined as a sequence of plans to get steam or geothermal fluids to satisfy a previously known demand, and, under the best possible conditions, to obtain payment. This paper presents a cost model for nine wells drilled at the Cerro Prieto geothermal field in 2005 and 2006 to supply steam to the power plants operating in the field. The cost model is based on the well cost, the initial steam production, the annual decline of steam, the drilling schedule and the break-even point for each well. The model shows the cost of steam by the ton and the sale price needed to determine the discount rate and the investment return time. [Spanish] Un proyecto de perforacion de pozos geotermicos puede definirse como una secuencia o sucesion de planes para obtener vapor o fluidos geotermicos destinados a satisfacer una demanda previamente determinada, que se emplearan principalmente para generar energia electrica, bajo las mejores condiciones para obtener un pago. Este trabajo presenta un modelo de costeo para nueve pozos en el campo geotermico de Cerro Prieto, que fueron perforados entre 2005 y 2006 como parte del suministro de vapor para las plantas generadoras que operan en este campo. El modelo de costeo se basa en el costo por pozo, la produccion inicial de vapor, la declinacion anual de vapor, los intereses de las obras de perforacion y el punto de equilibrio para cada pozo. Los resultados permiten conocer el costo de la tonelada de vapor y el precio de venta para determinar la tasa de descuento y el tiempo de retorno de la inversion.
Analysis of P- and S-wave VSP (vertical seismic profile) data from the Salton Sea Geothermal Field
Daley, T.M.
To understand any geophysical data, geologic information is necessary. This thesis will begin with a summary of the geology of the Salton Trough region and the Salton Sea Geothermal Field (SSGF). The information available from the SSSDP will also be summarized. After the geologic summary, the design of the VSP will be discussed, including acquisition equipment and procedures. The data processing procedures and software used will be discussed as a separate section. Processing procedures will also be described at various times in the thesis where more specialized procedures are used. Data analysis makes up the bulk of the thesis and it is divided into a number of sections detailing the basic VSP interpretation, the anisotropy analysis and the fracture detection and orientation analysis. A combined interpretation of the results, with probable geologic causes for observed events, is presented as a separate section from the data analysis. Finally, a summary of results for each of the goals stated above will be given. The reader should note that a large volume of data were collected and various display methods were used (from the standard wiggle-trace to three-component hodographs). Much of these data are left in the appendices with important or representative figures given in the body of the thesis. Also given in the appendices are listings of FORTRAN programs developed in conjunction with the thesis work. 46 refs., 63 figs., 12 tabs.
Imperial County geothermal development annual meeting: summary
All phases of current geothermal development in Imperial County are discussed and future plans for development are reviewed. Topics covered include: Heber status update, Heber binary project, direct geothermal use for high-fructose corn sweetener production, update on county planning activities, Brawley and Salton Sea facility status, status of Imperial County projects, status of South Brawley Prospect 1983, Niland geothermal energy program, recent and pending changes in federal procedures/organizations, plant indicators of geothermal fluid on East Mesa, state lands activities in Imperial County, environmental interests in Imperial County, offshore exploration, strategic metals in geothermal fluids rebuilding of East Mesa Power Plant, direct use geothermal potential for Calipatria industrial Park, the Audubon Society case, status report of the Cerro Prieto geothermal field, East Brawley Prospect, and precision gravity survey at Heber and Cerro Prieto geothermal fields. (MHR)
Geothermal energy sources and possibilities of their exploitation
The geothermal energy is everywhere beneath the surface of the earth. The earth's interior is enormous thermal reservoir of energy, which can be utilized if favorable geological conditions exist. The electricity generation in 1942 at Larderello was a commercial success. The installed geo-thermoelectric capacity had reached 127 650 kWe. Several countries were soon to follow the example set by Italy. In 1919, first geothermal wells were drilled at Beppu in Japan, followed in 1921 by wells drilled at The Geysers, California, USA. In 1958 a small geothermal power plant began operating in New Zealand; in 1959 another one in Mexico, in 1960 in the USA, followed by many other countries in the years to come. The heat source can be either a very high temperature (> 600 grad C) magmatic intrusion reaching relatively shallow depths (5-10 km) or, as in certain low-temperature systems at the Earth's normal temperature, which increases with depth. The reservoir is a volume of hot permeable rocks from which circulating fluids extract the heat. The reservoir is generally overlain by a cover of impermeable rocks and connected to a superficial recharge area through which the meteoric waters can replace or partly replace the fluids that escape from the reservoir through springs or are extracted by boreholes. The geothermal fluid is water, in majority of cases the meteoric water, in the liquid or vapour phase, depending on its temperature and pressure. This water often carries chemicals and gases such as CO2, H2S, etc. Another source of underground heat is so called the hot dry rock. The mater is to extract heat by creating a subsurface fracture system to which water can be added through injection wells. A creation of enhanced, or engineered, geothermal system requires improving the natural permeability of rock. Rocks are permeable due to minute fractures and pore spaces between mineral grains. The injected water is heated by a contact with the rock and returns to the surface through
This article takes a look at how geothermal energy can not only be used to supply heating energy, but also be used to provide cooling too. The article reports on a conference on heating and cooling with geothermal energy that was held in Duebendorf, Switzerland, in March 2008. The influence of climate change on needs for heating and cooling and the need for additional knowledge and data on deeper rock layers is noted. The seasonal use of geothermal systems to provide heating in winter and cooling in summer is discussed. The planning of geothermal probe fields and their simulation is addressed. As an example, the geothermal installations under the recently renewed and extended 'Dolder Grand' luxury hotel in Zurich are quoted. The new SIA 384/6 norm on geothermal probes issued by the Swiss Association of Architects SIA is briefly reviewed.
Geothermal systems: Principles and case histories
Rybach, L.; Muffler, L. J. P.
The classification of geothermal systems is considered along with the geophysical and geochemical signatures of geothermal systems, aspects of conductive heat transfer and regional heat flow, and geothermal anomalies and their plate tectonic framework. An investigation of convective heat and mass transfer in hydrothermal systems is conducted, taking into account the mathematical modelling of hydrothermal systems, aspects of idealized convective heat and mass transport, plausible models of geothermal reservoirs, and preproduction models of hydrothermal systems. Attention is given to the prospecting for geothermal resources, the application of water geochemistry to geothermal exploration and reservoir engineering, heat extraction from geothermal reservoirs, questions of geothermal resource assessment, and environmental aspects of geothermal energy development. A description is presented of a number of case histories, taking into account the low enthalpy geothermal resource of the Pannonian Basin in Hungary, the Krafla geothermal field in Northeast Iceland, the geothermal system of the Jemez Mountains in New Mexico, and extraction-reinjection at the Ahuachapan geothermal field in El Salvador.
Gas geochemistry of Los Humeros geothermal field, Mexico; Geoquimica de gases del campo geotermico de Los Humeros, Puebla, Mexico
Barragan R, Rosa Maria; Arellano G, Victor M; Nieva G, David; Portugal M, Enrique; Garcia G, Alfonso; Aragon A, Alfonso [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico); Torres A, Ignasio S [Centro de Investigacion en Energia, Temixco, Morelos (Mexico); Tovar A, Rigoberto [Comision Federal de Electricidad, Los Humeros, Puebla (Mexico)
Gas data of Los Humeros geothermal field were analyzed. A new method, which is based on the Fischer-Tropch reactions and on the combined pyrite-magnetite mineral equilibrium, was used. Reservoir temperature and reservoir excess steam were estimated for the starting stage of the field by using early data taken from producing wells at controlled conditions. The same parameters were also obtained for the present stage by using 1997 gas data. Reservoir temperatures ranged from 275 and 337 Celsius degrees and positive values for reservoir excess steam fractions were obtained for the starting stage. For well H-1 no excess steam was found since this well was fed by the shallower liquid-dominated reservoir. Results for 1997 showed lower scattering compared to early data and the possible occurrence of a heating process in the shallower stratum which could due to exploitation. [Spanish] En este articulo se presenta un analisis de datos de la fase gaseosa producida por pozos productores del campo geotermico de Los Humeros mediante un metodo que considera el equilibrio de la reaccion de Fischer-Tropsh y el equilibrio de minerales pirita-hematia y pirita-magnetita. Este metodo provee la temperatura del yacimiento y el exceso de vapor presente en la descarga total de los pozos. Los resultados se discuten tanto para el estado inicial del yacimiento utilizando los primeros datos de produccion en los que el flujo del pozo estuvo controlado y los obtenidos en 1997 que representan el estado actual del yacimiento. En el estado inicial se estimaron temperaturas de yacimiento de entre 275 y 337 grados Celsius y excesos de vapor positivos, con excepcion del pozo H-1 que se alimenta del estrato somero dominado por liquido. Los resultados obtenidos para 1997 muestran una dispersion menor y la probable ocurrencia de un proceso de calentamiento del estrato somero propiciado por la explotacion.
Breakdown of doublet recirculation and direct line drives by far-field flow in reservoirs: implications for geothermal and hydrocarbon well placement
Weijermars, R.; van Harmelen, A.
An important real world application of doublet flow occurs in well design of both geothermal and hydrocarbon reservoirs. A guiding principle for fluid management of injection and extraction wells is that mass balance is commonly assumed between the injected and produced fluid. Because the doublets are considered closed loops, the injection fluid is assumed to eventually reach the producer well and all the produced fluid ideally comes from stream tubes connected to the injector of the well pair making up the doublet. We show that when an aquifer background flow occurs, doublets will rarely retain closed loops of fluid recirculation. When the far-field flow rate increases relative to the doublet's strength, the area occupied by the doublet will diminish and eventually vanishes. Alternatively, rather than using a single injector (source) and single producer (sink), a linear array of multiple injectors separated by some distance from a parallel array of producers can be used in geothermal energy projects as well as in waterflooding of hydrocarbon reservoirs. Fluid flow in such an arrangement of parallel source-sink arrays is shown to be macroscopically equivalent to that of a line doublet. Again, any far-field flow that is strong enough will breach through the line doublet, which then splits into two vortices. Apart from fundamental insight into elementary flow dynamics, our new results provide practical clues that may contribute to improve the planning and design of doublets and direct line drives commonly used for flow management of groundwater, geothermal and hydrocarbon reservoirs.
Correlation of wireline log characteristics with hydrothermal alteration and other reservoir properties of the Salton Sea and Westmorland geothermal fields, Imperial Valley, California, USA
Muramoto, F.S.; Elders, W.A.
A detailed study of wireline logs from 11 wells in the Salton Sea and Westmorland geothermal systems was undertaken in order to determine the effects of hydrothermal alteration on the response of electrical and gamma-gamma density well logs. For the Salton Sea geothermal field, definite correspondence between log responses and hydrothermal mineralogy is evident, which in turn is related to the physical properties of the rocks. Three hydrothermal and one unaltered zone can be identified from log data on shales. These are: (1) the unaltered montmorillonite zone (<100/sup 0/ to 190/sup 0/C); (2) the illite zone (100/sup 0/ to 190/sup 0/C to 230/sup 0/ to 250/sup 0/C); (3) the chlorite zone (230/sup 0/ to 250/sup 0/C to 290/sup 0/ to 300/sup 0/C); and (4) the feldspar zone (>290/sup 0/ to 300/sup 0/C). The characteristic responses on well logs by which these zones are identified result primarily from changes in clay mineralogy of the shales and increases in density with progressive hydrothermal metamorphism. In the Westmorland geothermal field, differentiating mineral zones from log responses was only partially successful. However, analyses of both well log and petrologic data for wells Landers 1 and Kalin Farms 1 suggest that the former is heating up and the latter is cooling.
Breakdown of doublet re-circulation and direct line drives by far-field flow in reservoirs: Implications for geothermal and hydrocarbon well placement
Weijermars, R.; van Harmelen, A.
An important real world application of doublet flow occurs in well design of both geothermal and hydrocarbon reservoirs. A guiding principle for fluid management of injection and extraction wells is that mass balance is commonly assumed between the injected and produced fluid. Because the doublets are considered closed loops, the injection fluid is assumed to eventually reach the producer well and all the produced fluid ideally comes from stream tubes connected to the injector of the well pair making up the doublet. We show that when an aquifer background flow occurs, doublets will rarely retain closed loops of fluid re-circulation. When the far-field flow rate increases relative to the doublet's strength, the area occupied by the doublet will diminish and eventually vanishes. Alternatively, rather than using a single injector (source) and single producer (sink), a linear array of multiple injectors separated by some distance from a parallel array of producers can be used in geothermal energy projects as well as in waterflooding of hydrocarbon reservoirs. Fluid flow in such an arrangement of parallel source-sink arrays is shown to be macroscopically equivalent to that of a line doublet. Again, any far-field flow that is strong enough will breach through the line doublet, which then splits into two vortices. Apart from fundamental insight into elementary flow dynamics, our new results provide practical clues that may contribute to improve the planning and design of doublets and direct line drives commonly used for flow management of groundwater, geothermal and hydrocarbon reservoirs.
<正>20122531 Hu Lingzhi ( Institute of Geological Engineering Design & Research of Beijing,Miyun 101500,China );Wang Jiankang Discussion on the Feasibility of Geothermal Resources Development and Utilization in Miyun District,Beijing ( City Geology,ISSN1007-1903,CN11-5519 / P,6 ( 3 ), 2011,p.34-35,59 ,) Key words:geothermal resources,Beijing Geothermal,as a new type of clean energy with the integrated trinity of " heat energy-mineral resource-water resource ",
A Status Report on the Exploitation Conditions of the Ahuachapan Geothermal Field
Rivera-R., Jesus; Vides-R., Alberto; Cuellar, Gustavo; Samaniego-V., Fernando; Neri-I, Gustavo
The present exploitation conditions of the Ahuachapan field are discussed. The high well density in a small area has resulted in a significant reservoir pressure decrease due to the inherent reservoir over-exploitation. The average pressure in the exploitation zone has decreased from the 1975 value of 34 kg/cm{sup 2} to the May 1983 value of 23 kg/cm{sup 2}. The production decline characteristics of the Ahuachapan wells were examined, concluding that all wells but Ah-22 show exponential decline. The cumulative production-reinjection for the field up to April 1983 is 159.090 x 10{sup 6} tons, and 37.592 x 10{sup 6} tons, respectively. The effect of reinjection upon field behavior is evident when observing the pressure decline characteristics of the field. It is seen that for indection fraction related to total mass extracted above 30 percent, the average decline pressure in the production area becomes approximately stabilized. If this condition is not met the reservoir pressure decreases sharply. From this finding it is concluded that a careful and properly planned reinjection program is a must for the field. The observed temperature reduction in some of the wells seems to be the result of two operating mechanisms. First, we have the pressure decline that produces water vaporization and the consequent temperature descend. Analysis of information available shows no clear indication of deleterious temperature effects on the producing wells due to injection. The only exception observed to date is well Ah-5 that because its close distance and its relative structural position and direct hydraulic connection to injector Ah-29, presented conditions for fast displacement of the thermal front, resulting in unsufficient contact area and residence time for reheating of the injected water.
Numerical simulation of heat production potential from hot dry rock by water circulating through two horizontal wells at Desert Peak geothermal field
In this work, heat production potential from hot dry rock by water circulating through two horizontal wells was numerically investigated based on the geological data of well DP23-1 under the enhanced geothermal system (EGS) project at Desert Peak geothermal field. The results indicate that the desirable electricity production power and energy efficiency can be obtained under suitable reservoir permeability, water production rate and injection temperature; meanwhile water flow impedance remains at a relative lower level. The sensitivity analysis indicates that the electricity production power mainly depends on the water production rate and the injection temperature; the water flow impedance mainly depends on the reservoir permeability, water production rate and injection temperature; the energy efficiency mainly depends on the reservoir permeability and the water production rate. The heat production performance will be improved when the reservoir permeability, the water production rate and the injection temperature are under reasonable conditions. However, this study is based on that the fractured reservoir is equivalent to a homogeneous porous medium and there is no water loss in the reservoir, so the practical energy output and efficiency of water circulating through two horizontal wells at Desert Peak geothermal field needs further study in the future. - Highlights: • We established a numerical model of two horizontal-well enhanced geothermal system. • Desirable heat production performance can be obtained under suitable conditions. • Electricity power depends on water injection rate and injection temperature. • Reservoir impedance depends on reservoir permeability, water production rate and injection temperature. • Energy efficiency depends on reservoir permeability and water production rate