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Sample records for miravalles geothermal field

  1. Preliminary reservoir engineering studies of the Miravalles geothermal field, Costa Rica

    SciTech Connect

    Haukwa, C.; Bodvarsson, G.S. Lippmann, M.J.; Mainieri, A.

    1992-01-01

    The Earth Sciences Division of Lawrence Berkeley Laboratory in cooperation with the Instituto Costarricense de Electricidad is conducting a reservoir engineering study of the Miravalles geothermal field, Costa Rica. Using data from eight exploration wells a two-dimensional areal, natural-state model of Miravalles has been developed. The model was calibrated by fitting the observed temperature and pressure distributions and requires a geothermal upflow zone in the northern part of the field, associated with the Miravalles volcano and an outflow towards the south. The total hot (about 260{degrees}C) water recharge is 130 kg/s, corresponding to a thermal input of about 150 MWt. On the basis of the natural-state model a two-dimensional exploitation model was develope. The field has a production area of about 10 km{sup 2}, with temperatures exceeding 220{degrees}C. The model indicated that power generation of 55 MWe can be maintained for 30 years, with or without injection of the separated geothermal brine. Generation of 110 MWe could be problematic. Until more information becomes available on the areal extent of the field and the properties of the reservoir rocks, especially their relative permeability characteristics, it is difficult to ascertain if 110 MWe can be sustained during a 30-year period.

  2. Preliminary reservoir engineering studies of the Miravalles geothermal field, Costa Rica

    SciTech Connect

    Haukwa, C.; Bodvarsson, G.S. Lippmann, M.J. ); Mainieri, A. )

    1992-01-01

    The Earth Sciences Division of Lawrence Berkeley Laboratory in cooperation with the Instituto Costarricense de Electricidad is conducting a reservoir engineering study of the Miravalles geothermal field, Costa Rica. Using data from eight exploration wells a two-dimensional areal, natural-state model of Miravalles has been developed. The model was calibrated by fitting the observed temperature and pressure distributions and requires a geothermal upflow zone in the northern part of the field, associated with the Miravalles volcano and an outflow towards the south. The total hot (about 260[degrees]C) water recharge is 130 kg/s, corresponding to a thermal input of about 150 MWt. On the basis of the natural-state model a two-dimensional exploitation model was develope. The field has a production area of about 10 km[sup 2], with temperatures exceeding 220[degrees]C. The model indicated that power generation of 55 MWe can be maintained for 30 years, with or without injection of the separated geothermal brine. Generation of 110 MWe could be problematic. Until more information becomes available on the areal extent of the field and the properties of the reservoir rocks, especially their relative permeability characteristics, it is difficult to ascertain if 110 MWe can be sustained during a 30-year period.

  3. Preliminary reservoir engineering studies of the Miravalles geothermal field, Costa Rica

    SciTech Connect

    Haukwa, C.; Bodvarsson, G.S.; Lippmann, M.J.; Mainieri, A.

    1992-01-01

    The Earth Sciences Division of Lawrence Berkeley Laboratory in cooperation with the Instituto Costarricense de Electricidad is conducting a reservoir engineering study of the Miravalles geothermal field, Costa Rica. Using data from eight exploration wells, a two-dimensional areal, natural-state model of Miravalles has been developed. The model was calibrated by fitting the observed temperature and pressure distributions and requires a geothermal upflow zone in the northern part of the field, associated with the Miravalles volcano and an outflow towards the south. The total hot (about 260 C) water recharge is 130 kg/s, corresponding to a thermal input of about 150 MWt. On the basis of the natural-state model a two-dimensional exploitation model was developed. The field has a production area of about 10 km{sup 2}, with temperatures exceeding 220 C. The model indicated that power generation of 55 MWe can be maintained for 30 years, with or without injection of the separated geothermal brine. Generation of 110 MWe could be problematic. Until more information becomes available on the areal extent of the field and the properties of the reservoir rocks, especially their relative permeability characteristics, it is difficult to ascertain if 110 MWe can be sustained during a 30-year period.

  4. Preliminary reservoir engineering studies of the Miravalles geothermal field, Costa Rica

    NASA Astrophysics Data System (ADS)

    Haukwa, C.; Bodvarsson, G. S.; Lippmann, M. J.; Mainieri, A.

    1992-01-01

    The Earth Sciences Division of Lawrence Berkeley Laboratory in cooperation with the Instituto Costarricense de Electricidad is conducting a reservoir engineering study of the Miravalles geothermal field, Costa Rica. Using data from eight exploration wells, a two-dimensional areal, natural-state model of Miravalles has been developed. The model was calibrated by fitting the observed temperature and pressure distributions and requires a geothermal upflow zone in the northern part of the field, associated with the Miravalles volcano and an outflow towards the south. The total hot (about 260 C) water recharge is 130 kg/s, corresponding to a thermal input of about 150 MWt. On the basis of the natural-state model, a two-dimensional exploitation model was developed. The field has a production area of about 10 km(exp 2), with temperatures exceeding 220 C. The model indicated that power generation of 55 MWe can be maintained for 30 years, with or without injection of the separated geothermal brine. Generation of 110 MWe could be problematic. Until more information becomes available on the areal extent of the field and the properties of the reservoir rocks, especially their relative permeability characteristics, it is difficult to ascertain if 110 MWe can be sustained during a 30-year period.

  5. Calcite deposition at Miravalles geothermal field, Costa Rica

    SciTech Connect

    Vaca, L.; Alvarado, A.; Corrales, R. )

    1989-01-01

    The calcite deposition problem at Miravalles has been studied since it was observed in the first three wells drilled on the slopes of the Miravalles Volcano. Long-term tests have been carried out to study reservoir characteristics. The change in the production behavior of the wells with the restriction imposed by the deposited calcite has been studied trying to evaluate and quantify the scaling problem. Work is being done on predictions of the deposition rate, location and distribution of the deposited mineral inside the wells. This work was compared with real data obtained from caliper logs of the wells before and after production. The feasibility of the first 55 MW power plant has been demonstrated. It was considered that the solution for the calcite problem is the reaming during discharge of the wells trying at the same time to minimize the cleaning interventions with a new well design. It is believed, due to the thermodynamics and chemical characteristics of the extracted fluids, that it is possible to find a non-deposition zone which will permit the drilling of wells without a scaling problem.

  6. Fluid-inclusion evidence for previous higher temperatures in the miravalles geothermal field, Costa Rica

    USGS Publications Warehouse

    Bargar, K.E.; Fournier, R.O.

    1988-01-01

    Heating and freezing data were obtained for liquid-rich secondary fluid inclusions in magmatic quartz, hydrothermal calcite and hydrothermal quartz crystals from 19 sampled depths in eight production drill holes (PGM-1, 2, 3, 5, 10, 11, 12 and 15) of the Miravalles geothermal field in northwestern Costa Rica. Homogenization temperatures for 386 fluid inclusions range from near the present measured temperatures to as much as 70??C higher than the maximum measured well temperature of about 240??C. Melting-point temperature measurements for 76 fluid inclusions suggest a calculated salinity range of about 0.2-1.9 wt% NaCl equivalent. Calculated salinities as high as 3.1-4.0 wt% NaCl equivalent for 20 fluid inclusions from the lower part of drill hole PGM-15 (the deepest drill hole) indicate that higher salinity water probably was present in the deeper part of the Miravalles geothermal field at the time these fluid inclusions were formed. ?? 1988.

  7. Closed-loop flow test Miravalles Geothermal Field well log results

    SciTech Connect

    Dennis, B.; Eden, G.; Lawton, R.

    1992-10-01

    The Instituto Costarricense de Electricidad (ICE) conducted a closed-loop flow test in the Miravalles Geothermal Field. The closed-loop test was started in May and ran through August of 1990. The effluent from the production well PG-11 was carried by a pipeline through a monitor station to the injection well PG-2. Before starting the long-term flow test in May, cold-water injection experiments were performed in each well to determine the pressure and temperature response. A series of downhole measurements were made in each well to obtain background information. The downhole measurements were repeated in August just before terminating the flow test to evaluate the results.

  8. Closed-loop flow test Miravalles Geothermal Field well log results

    SciTech Connect

    Dennis, B.; Eden, G.; Lawton, R.

    1992-01-01

    The Instituto Costarricense de Electricidad (ICE) conducted a closed-loop flow test in the Miravalles Geothermal Field. The closed-loop test was started in May and ran through August of 1990. The effluent from the production well PG-11 was carried by a pipeline through a monitor station to the injection well PG-2. Before starting the long-term flow test in May, cold-water injection experiments were performed in each well to determine the pressure and temperature response. A series of downhole measurements were made in each well to obtain background information. The downhole measurements were repeated in August just before terminating the flow test to evaluate the results.

  9. Results of investigation at the Miravalles Geothermal Field, Costa Rica: Part 1, Well logging. Resultados de las investigaciones en el campo geotermico de Miravalles, Costa Rica: Parte 1, Registros de pozos

    SciTech Connect

    Dennis, B.R.; Lawton, R.G.; Kolar, J.D.; Alvarado, A.

    1989-03-01

    The well-logging operations performed in the Miravalles Geothermal Field in Costa Rica were conducted during two separate field trips. The Phase I program provided the deployment of a suite of high-temperature borehole instruments, including the temperature/rabbit, fluid sampler, and three-arm caliper in Well PGM-3. These same tools were deployed in Well PGM-10 along with an additional survey run with a combination fluid velocity/temperature/pressure instrument used to measure thermodynamic properties under flowing well conditions. The Phase II program complemented Phase I with the suite of tools deployed in Wells PGM-5, PGM-11, and PGM-12. 4 refs., 25 figs., 1 tab.

  10. Results of investigation at the Miravalles geothermal field, Costa Rica. Resultados de las investigaciones en el campo geotermico de Miravalles, Costa Rica; Parte 2, Muestreo de fluidos pozo abajo

    SciTech Connect

    Grigsby, C.O.; Goff, F.; Trujillo, P.E. Jr.; Counce, D.A.; Dennis, B.; Kolar, J.; Corrales, R.; Instituto Costarricense de Electricidad, San Jose )

    1989-10-01

    Samples of the geothermal fluids in the Miravalles, Costa Rica, geothermal system were collected from production wellbores using downhole fluid samplers, from flowing wellheads using miniseparators, and from hot springs that discharge in the area. The reservoir fluid at Miravalles is a neutral-chloride-type water, but fumaroles and acid-sulfate springs are present within the main thermal area, and there are bicarbonate-rich hot springs that are clearly related to the neutral-chloride reservoir fluids. Dissolved gases are primarily a mixture of CO{sub 2} with air, but samples collected in the fumarolic areas also contain H{sub 2}S. Water-stable isotope analyses suggest local meteoric recharge, and the reservoir fluid shows oxygen isotopic shifts of about 2.5% due to high-temperature oxygen exchange between water and rock. Chemical geothermometer temperatures are consistent with the measured downhole temperature of 220{degrees} to 255{degrees}C. This pattern of neutral-chloride reservoir fluids with acid-sulfate springs near the source region and bicarbonate-rich chloride hot springs at the periphery of the system suggests a lateral outflow type of hydrothermal system. In addition to the geochemical evidence, temperature profiles from several of the wells show temperature reversals that are characteristic of lateral outflow plumes. We find no evidence for the underlying, higher temperature (300{degrees}C) system, which has been suggested by other investigators. 24 refs., 14 figs., 6 tabs.

  11. Secondary mineral growth in fractures in the Miravalles geothermal system, Costa Rica

    SciTech Connect

    Rochelle, C.A. . Dept. of Earth Sciences); Milodowski, A.E.; Savage, D. . Fluid Processes Research Group); Corella, M. )

    1989-01-01

    A mineralogical, fluid-chemical, and theoretical study of hydrothermal alteration in veins from drillcore from the Miravalles geothermal field, Costa Rica has revealed a complex history of mineral-fluid reaction which may be used to characterize changes in temperature and fluid composition with time. Mineralogical and mineral-chemical data are consistent with hydrothermal alteration in the temperature range 200{sup 0}-270{sup 0}C, with deeper portions of the system having undergone temperatures in excess of 300{sup 0}C. Thermodynamic calculations suggest that the observed alteration assemblage is not equilibrium with current well fluids, unless estimates of reservoir pH are incorrect. Fe-Al zoning of prehnite and epidote in veins is consistent with rapid, isothermal fluctuations in fluid composition at current reservoir temperatures, and may be due to changes in volatile content of the fluid due to tectonic activity.

  12. Reinjected water return at Miravalles geothermal reservoir, Costa Rica: Numerical modelling and observations

    SciTech Connect

    Parini, Mauro; Acuna, Jorge A.; Laudiano, Michele

    1996-01-24

    The first 55 MW power plant at Miravalles started operation in March, 1994. During the first few months of production, a gradual increase in chloride content was observed in some production wells. The cause was assumed to be a rapid return of injectate from two in.jection wells located fairly near to the main production area. A tracer test was performed and showed a relatively rapid breakthrough, confirming the assumption made. Numerical modeling was then carried out to try to reproduce the observed behavior. The reservoir was modelled with an idealized three-dimensional network of fractures embedded into a low permeability matrix. The “two waters” feature of TOUGH2 simulator was used. The numerical simulation showed good agreement with observations. A “porous medium” model with equivalent hydraulic characteristics was unable to reproduce the observations. The fractured model, when applied to investigate the mid and long term expected behavior, indicated a reservoir cooling risk associated to the present injection scheme. Work is currently underway to modify this scheme.

  13. Reinjected water return at Miravalles geothermal reservoir, Costa Rica: Numerical modelling and observations

    SciTech Connect

    Parini, M.; Laudiano, M.; Acuna, J.A.

    1996-12-31

    The first 55 MW power plant at Miravalles started operation in March, 1994. During the first few months of production, a gradual increase in chloride content was observed in some production wells. The cause was assumed to be a rapid return of injectate from two injection wells located fairly near to the main production area. A tracer test was performed and showed a relatively rapid breakthrough, confirming the assumption made. Numerical modeling was then carried out to try to reproduce the observed behavior. The reservoir was modelled with an idealized three-dimensional network of fractures embedded into a low permeability matrix. The {open_quotes}two waters{close_quotes} feature of TOUGH2 simulator was used. The numerical simulation showed good agreement with observations. A {open_quotes}porous medium{close_quotes} model with equivalent hydraulic characteristics was unable to reproduce the observations. The fractured model, when applied to investigate the mid and long term expected behavior, indicated a reservoir cooling risk associated to the present injection scheme. Work is currently underway to modify this scheme.

  14. Use of reaction path modeling to identify the processes governing the generation of neutral Na-Cl and acidic Na-Cl-SO 4 deep geothermal liquids at Miravalles geothermal system, Costa Rica

    NASA Astrophysics Data System (ADS)

    Marini, Luigi; Yock Fung, Antonio; Sanchez, Eddy

    2003-12-01

    The EQ3/6 Software Package was used to investigate the irreversible water-rock mass exchanges governing the production of neutral Na-Cl and acidic Na-Cl-SO 4 geothermal liquids circulating at depth into the Miravalles geothermal system. First, we reconstructed the in-situ reservoir composition, including pH, we evaluated the boundary conditions ( PCO 2, PH 2S , and/or PO 2), which are necessary for the implementation of reaction path modeling, we estimated the thermodynamic affinity of the reservoir liquids with respect to relevant hydrothermal solid phases, and we identified possible compositions of the initially acidic meteoric-magmatic liquids. Then we modeled both the interaction between meteoric-magmatic fluids and calc-alkaline volcanic rocks and the interaction between neutral Na-Cl waters and highly altered volcanic rocks. Reaction path modeling was performed through a purely stoichiometric approach without considering the kinetics of irreversible mass exchanges. Results of reaction path modeling suggest that the neutral Na-Cl liquids hosted in the Miravalles geothermal reservoirs are produced through interaction between initially acidic, magmatic-meteoric aqueous solutions and volcanic rocks and represent the final product of this process. However, the deep acid Na-Cl-SO 4 liquids of Miravalles are not intermediate products in this process. They are instead generated through interaction of neutral Na-Cl waters with volcanic rocks affected by advanced argillic alteration, representing old solfataras buried by later volcanics, as suggested by Robert O. Fournier about 10 years ago.

  15. The geothermal fields of the Kenya rift

    NASA Astrophysics Data System (ADS)

    Riaroh, Don; Okoth, William

    1994-09-01

    From the standpoint of geothermal energy, Kenya's resources are due to the presence of the Kenya rift which is part of the East African rift system. Geological, geophysical and geothermal studies indicate that Neogene volcanic activity has led to the presence of near surface heat generating sources. Geothermal fields of the Kenya rift occur in two types of environments. The main geothermal fields are associated with Quaternary volcanoes. The second type is associated with fissures that are related to active fault zones. In either case, these fields are dissected by numerous rift faults that give rise to a number of geothermal springs and fumaroles.

  16. Deformation study of Kamojang geothermal field

    NASA Astrophysics Data System (ADS)

    Ramdhani, B. D.; Meilano, I.; Sarsito, D. A.

    2017-07-01

    GPS has proven to be an indispensable tool in the effort to understand crust deformation before, during, and after the big earthquake events through data analysis and numerical simulation. The development of GPS technology has been able to prove as a method for the detection of geothermal activity that related to deformation. Furthermore, the correlation of deformation and geothermal activity are related to the analysis of potential hazards in the geothermal field itself. But unfortunately, only few GPS observations established to see the relationship of tectonic and geothermal activity around geothermal energy area in Indonesia. This research will observe the interaction between deformation and geothermal sources around the geothermal field Kamojang using geodetic GPS. There are 4 campaign observed points displacement direction to north-east, and 2 others heading to south-east. The displacement of the observed points may have not able proven cause by deformation of geothermal activity due to duration of observation. Since our research considered as pioneer for such investigation in Indonesia, we expect our methodology and our findings could become a starter for other geothermal field cases in Indonesia.

  17. Klamath Falls geothermal field, Oregon

    SciTech Connect

    Lienau, P.J.; Culver, G.; Lund, J.W.

    1989-09-01

    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.

  18. A database for the Geysers geothermal field

    SciTech Connect

    Ripperda, M.; Bodvarsson, G.S.

    1988-10-01

    A general use menu driven software package has been developed that stores and retrieves geothermal field data and produces a large variety of graphic displays. These include, for example, production plots, cross-sections, contour plots, base maps and Horner plots. This software package has been applied to the Geysers geothermal field which has open file data for over 200 wells. The data include production histories, directional surveys, lithology logs, wellhead temperatures and pressures, digitized base maps, steam entry locations, casing diagrams, pressure transient tests, heat flow measurements and noncondensible gas concentrations. Although the software was developed for use with data from the Geysers, it can be used with data from any geothermal reservoir. 2 refs., 5 figs.

  19. Reservoir engineering of Wairakei geothermal field

    SciTech Connect

    Grant, Malcom A.

    1988-01-01

    Wairakei was the first liquid dominated geothermal field exploited for major power production. As such many decisions were taken on an ad-hoc or experimental basis. In retrospect the choice of Wairakei was fortunate : with extensive shallow high permeability and major recharge it is an easy field to exploit. This lecture describes the history of the field and the contribution of reservoir engineering to field management, and describes the reservoir as it is now understood.

  20. Geothermal Field Development in Mexico

    SciTech Connect

    Espinosa, Hector Alonso

    1983-12-15

    Mexico is a Country characterized by its diversified means of Power Gerneration. Actual installed capacity is almost 19000 MW, of which 205 MW corresponds to Geothermal Plants, that is, 180 MW in Cerro Prieto and 25 MW of Portable Plants in Los Azufres. To date, 346 area with exploitation possibilites, are known. They are mainly distributed along the Volcanic Belt where the most prominent are, Los Azufres, La Primavera, Los Humeros, Ixtlan De Los Hervores and Los Negritos, among others. Proved reserves are 920 MW, and the accessible resource base are 4600 MW identified and 6000 MW undiscovered. The long range construction studies intends to achieve a total installed capacity of 100000 MW, by the end of this century, including 2000 MW Geothermal, through conventional and Portable Plants. It is not a definite program but a development strategy. The carrying out of a definite program, will depend upon the confirmation of Hypothesis made in previous studies, and the economic decisions related to the financial sources availability, and techologies to be used in the future as well.

  1. Cerro Prieto geothermal field: exploration during exploitation

    SciTech Connect

    Not Available

    1982-07-01

    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.

  2. Direct use of the geothermal energy at Los Azufres geothermal field, Mexico

    SciTech Connect

    Sanchez-Velasco, E.; Casimiro-Espinoza, E.

    1995-12-31

    The main object of Comision Federal de Electricidad (CFE`s) Geothermal Field at Los Azufres, is to generate geothermal electricity; however with the new politics in Mexico, CFE has designed a pilot project in order to profit from the geothermal residual energy and to attract national or foreign investors and convince them that direct use of geothermal energy is an attractive feasible and economical project. The object of this paper is to present the CFE experiences in different pilot projects applied to direct uses of geothermal energy.

  3. Reservoir assessment of The Geysers Geothermal field

    SciTech Connect

    Thomas, R.P.; Chapman, R.H.; Dykstra, H.

    1981-01-01

    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.

  4. Wood and fruit drying in Los Azufres geothermal field, Mexico

    SciTech Connect

    Casimiro, E.; Pastrana, E.

    1996-12-31

    The main object of Comision Federal de Electricidad (CFE`s) Geothermal Field at Los Azufres, is to generate geothermal electricity; however with the new politics in Mexico CFE has built a pilot project in order to profit from the geothermal residual energy and to attract national or foreign investors and convince them that direct-use of geothermal energy is an attractive feasible and economical possibility. The object of this paper is to present the CFE experiences in wood and fruit drying using geothermal energy.

  5. Rare Earth Element Concentrations in Geothermal Wells at the Puna Geothermal Field, Hawaii

    DOE Data Explorer

    Fowler, Andrew; Zierenberg, Robert

    2016-12-09

    Rare earth element concentrations in the geothermal wells at the Puna geothermal field, Hawaii. Samples taken from geothermal wells KS-5, KS-6W, KS-9W, KS-14E, and KS-16N. Includes pH and concentrations for Cerium, Dysprosium, Erbium, Europium, Gadolinium, Holmium, Lanthanum, Lutetium, Neodymium, Praseodymium, Samarium, Terbium, Thulium, Yttrium, and Ytterbium. Samples collected on November 11-17, 2016.

  6. Optimization of injection scheduling in geothermal fields

    SciTech Connect

    Lovekin, J.

    1987-05-01

    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.

  7. Geothermal Resource Analysis and Structure of Basin and Range Systems, Especially Dixie Valley Geothermal Field, Nevada

    SciTech Connect

    David Blackwell; Kenneth Wisian; Maria Richards; Mark Leidig; Richard Smith; Jason McKenna

    2003-08-14

    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.

  8. Geology of the Olkaria Geothermal Field

    SciTech Connect

    Ogoso-Odongo, M.E.

    1986-01-01

    Up to now development of the resource in Olkaria geothermal field, Kenya, has been based on fragmental information that is inconclusive in most respects. Development has been concentrated in an area of 4 km/sup 2/ at most, with well to well spacing of less than 300 m. The move now is to understand the greater Olkaria field by siting exploratory wells in different parts of the area considered of reasonable potential. To correlate the data available from the different parts of the field, the geology of the area, as a base for the composite field model, is discussed and shown to have major controls over fluid movements in the area and other features.

  9. Pilot fruit drier for Los Azufres geothermal field, Michoacan, Mexico

    SciTech Connect

    Lund, J.W.

    1993-02-01

    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.

  10. Pilot fruit drier for Los Azufres geothermal field, Michoacan, Mexico

    SciTech Connect

    Lund, J.W.

    1993-02-01

    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.

  11. Origins of acid fluids in geothermal reservoirs

    USGS Publications Warehouse

    Truesdell, Alfred

    1991-01-01

    Acid fluids in geothermal reservoirs are rare. Their occurrence in geothermal systems associated with recent volcanism (Tatun, Sumikawa, Miravalles) probably indicates that the geothermal reservoir fluid was derived from volcanic fluid incompletely neutralized by reaction with feldspars and micas. Superheated steam containing HCl (Larderello, The Geysers) forms acid where it condenses or mixes with liquid at moderate temperatures (325??C). Cryptoacidity occurs at Los Humeros where HCl acidity is formed and neutralized without reaching the surface.

  12. Structural investigations of Great Basin geothermal fields: Applications and implications

    SciTech Connect

    Faulds, James E; Hinz, Nicholas H.; Coolbaugh, Mark F

    2010-11-01

    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.

  13. Geothermal field's interaction with geophysical fields of another nature

    SciTech Connect

    Novik, Oleg B.; Mikhailovskaya, Irina B.; Repin, Dmitry G.; Yershov, Sergey V.

    1996-01-24

    The energy balance of active lithosphere zones is to a large extent determined by nonstationary interaction of mechanical (elastic and hydrodynamic), thermal, electromagnetic, and gravitational geophysical fields. Seismic disturbances of electromagnetic and temperature fields, repeatedly observed before earthquakes are a striking manifestation of this interaction (Sec. 1). Technological processes of exploitation of hydrothermal deposits are determined by the interaction of hydrodynamical and temperature field (Sec. 2). These “fast” interactions (with the characteristic time scale from seconds to years) take place against the background of “slow” thermomechanical interactions (time scale of Myears), the latter determining the formation of regional geothermal fields (Sec. 3).

  14. Lidar search for atmospheric atomic mercury in Icelandic geothermal fields

    SciTech Connect

    Edner, H.; Faris, G.W.; Sunesson, A.; Svanberg, S. ); Bjarnason, J.O.; Kristmanndottir, H.; Sigurdsson, K.H. )

    1991-02-20

    A search for atmospheric atomic mercury as a possible tracer gas for geothermal energy exploration was performed in three Icelandic geothermal fields using differential absorption lidar technique. Contrary to expectations, concentrations basically only at the Atlantic background value of about 2 ng/m{sup 3} were found in Iceland.

  15. Seismic monitoring at the Geysers Geothermal Field

    SciTech Connect

    Romero, A.E. Jr.; Kirkpatrick, A.; Majer, E.L.; Peterson, J.E. Jr.

    1994-09-01

    This report summarizes the efforts of LBL to utilize MEQ data in reservoir definition as well as in evaluating its performance. Results of the study indicate that the velocity and attenuation variations correlate with the known geology of the field. At the NW Geysers, high velocity anomalies correspond to metagraywacke and greenstone units while low velocity anomalies seem to be associated with Franciscan melanges. Low Vp/Vs and high attenuation delineate the steam reservoir suggesting undersaturation of the reservoir rocks. Ongoing monitoring of Vp/Vs may be useful in tracking the expansion of the steam zone with time. Spatial and temporal patterns of seismicity exhibit compelling correlation with geothermal exploitation. Clusters of MEQs occur beneath active injection wells and appear to shift with changing injection activities. High resolution MEQ locations hold promise for inferring fluid flow paths, especially in tracking injectate. This study has demonstrated that continuous seismic monitoring may be useful as an active reservoir management tool.

  16. Geo-electrical Structures of QP Geothermal Field, Southwest Tibet

    NASA Astrophysics Data System (ADS)

    He, L.; Chen, L.; Wang, X.; Zhao, X.; Xi, X.; Chen, R.

    2016-12-01

    The QP geothermal field is one the high-temperature geothermal fields in the Himalayan Geothermal Belt (HGB) of the southwest Tibet. The HGB is tectonically active because of the ongoing collision of the Indian and Asian continents. More than a half of the high-temperature geothermal fields in China are concentrated in HGB. However, the structures and geothermal systems of most of the high-temperature geothermal fields are still poor understood, due largely to few geophysical explorations having been conducted in theses areas. Debates also continue as to whether there are melting magmas in the upper crust serving as the heat source in the HGB, although more and more evidence has been reported from studies of helium isotope composition of hot spring gas, geochemical characteristics of spring water, and temperature field modeling. We carried out a MT/AMT study to explore the geothermal system in the QP geothermal field. Our result provide resistivity models in the forms of profile section, contour map of iso-elevation and three dimension image for understanding the reservoir, thermal path and heat source of the QP geothermal system. The result shows that the QP geothermal system has four geo-electrical layers from surface to a depth of more than 10 km, and it displays geo-electrical structure features similar to that of some volcanoes in USA and Iceland. The reservoir of the QP geothermal field has a resistivity of 1-10 Ω.m. In particular, we found a deep buried low resistivity anomaly with a resistivity of 1-8 Ω.m at more than 7 km depths in the field. This low resistivity anomaly is interpreted as partial melting magmas in the upper crust based on the comprehensive understanding of the geophysical, geochemical and geological data in the QP geothermal field. The partial melting magmas serve as the heat source of the geothermal system. Our result provides new geophysical evidence for the occurrence of partial melting in the upper crust in South Tibet.

  17. Development of an Enhanced Two-Phase Production System at the Geysers Geothermal Field

    SciTech Connect

    Steven Enedy

    2001-12-14

    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.

  18. The Geothermal Field Camp: Capacity building for geothermal energy systems in Indonesia

    NASA Astrophysics Data System (ADS)

    Moeck, I.; Sule, R.; Saptadji, N. M.; Deon, F.; Herdianita, N. R.; Jolie, E.; Suryantini, N.; Erbas, K.

    2012-04-01

    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

  19. Geothermal Fields on the Volcanic Axis of Mexico

    SciTech Connect

    Mercado, S.; Gonzalez, A.

    1980-12-16

    At present in Mexico, geothermal energy is receiving a great impulse due to the excellent results obtained in the Cerro Prieto geothermal field, in which a geothermoelectric plant is operated. This plant has four units of 37.5 MW each, with a total capacity of 150 MW, and under program 470 MW more by 1984. The Government Institution, Comisi6n Federal de Electricidad, is in charge of the exploration and exploitation of geothermal fields as well as construction and operation of power plants in Mexico. By this time CFE has an extensive program of exploration in the central part of Mexico, in the Eje Neovolcdnico. In this area, several fields with hydrothermal alteration are under exploration, like the Michoac6n geothermal area, where Los Azufres geothermal field is being developed. Seventeen wells have been drilled and twelve of them presented excellent results, including two dry steam wells. In other areas, such as Arar6, Cuitzeo, San Agustln del Maiz,Ixtldn de Los Hervores and Los Negritos, geological, geophysical and geochemical explorations have been accomplished, including shallow well drilling with good results. Another main geothermal area is in the State of Jalisco with an extension of 5,000 m2, where La Primavera geothermal field shows a lot of volcanic domes and has an intensive hydrothermal activity. Deep wells have been drilled, one of them with a bottom temperature of 29OOC. Other fields in this area, like San Narcos, Hervores de La Vega, La Soledad, Villa Corona, etc., have a good geothermal potential. A new geothermal area has been explored recently in the eastern part of the country named Los Humeros, Puebla. In this area studies are being made and there are plans for well drilling exploration by the beginning of 1981. Like this one, there are many other areas in the country in which 300 hydrothermal alteration zones are been classified and 100 of them are considered economically exploitable.

  20. The Ahuachapan geothermal field, El Salvador: Reservoir analysis

    SciTech Connect

    Aunzo, Z.; Bodvarsson, G.S.; Laky, C.; Lippmann, M.J.; Steingrimsson, B.; Truesdell, A.H.; Witherspoon, P.A.; Icelandic National Energy Authority, Reykjavik; Geological Survey, Menlo Park, CA )

    1989-08-01

    These are appendices A thru E of the Ahuachapan geothermal field reservoir analysis. The volume contains: mineralogy contours, ionic chlorine and silicon dioxide contours, well summaries, and temperature and pressure effects. (JEF)

  1. The Ahuachapan geothermal field, El Salvador: Reservoir analysis

    SciTech Connect

    Aunzo, Z.; Bodvarsson, G.S.; Laky, C.; Lippmann, M.J.; Steingrimsson, B.; Truesdell, A.H.; Witherspoon, P.A.; Icelandic National Energy Authority, Reykjavik; Geological Survey, Menlo Park, CA; Lawrence Berkeley Lab., CA )

    1989-08-01

    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)

  2. Symposium in the field of geothermal energy

    SciTech Connect

    Ramirez, Miguel; Mock, John E.

    1989-04-01

    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.

  3. Summary of modeling studies of the Krafla geothermal field, Iceland

    SciTech Connect

    Bodvarsson, G.S.; Pruess, K.; Stefansson, V.; Eliasson, E.T.

    1983-08-01

    A comprehensive modeling study of the Krafla geothermal field in Iceland has been carried out. The study consists of four tasks: the analysis of well test data, modeling of the natural state of the field, the determination of the generating capability of the field, and modeling of well performance. The results of all four tasks are consistent with field observations.

  4. Matched Field Detection of Microseismicity in a Geothermal Field

    NASA Astrophysics Data System (ADS)

    Templeton, D. C.; Harris, D. B.

    2010-12-01

    The delineation of fractures in geothermal fields is an important aspect of reservoir management that often is attempted by mapping the distribution of microseismicity. Traditional methods of earthquake location frequently used for this purpose are labor-intensive, requiring phase-arrival picking and high-resolution location with a relative location routine such as hypoDD. Automatic picks often require assessment and correction by an analyst. Frequently, event superposition and poor signal-to-noise ratio limit the number of usable events to one-third or fewer of the detectable transients. In some applications smaller events may become so numerous that they come to resemble a continuous random process that is not amenable to location analysis suited to transient arrivals. We are exploring the application of matched field processing (MFP) to map emissions from a geothermal field. MFP is a technique developed in underwater sound to localize emissions from continuous sources such as submersibles. The technique resembles beamforming or FK analysis in that it focuses the wavefield emanating from a particular source location by matching, in the frequency domain, the phase and amplitude of waves incident across the observing aperture. It differs from beamforming and FK methods in that the phase and amplitude structure is not determined by a plane-wave model. Wavefield structure may be determined empirically, by measuring it from observations of reference events, or it may be developed by full-waveform synthetics computed through a velocity model of the medium. In this presentation, we explore the empirical approach. Our objective is to map all of the observable seismicity in a geothermal field, not just the larger events that are sufficiently distinct to permit accurate picks. Our approach would extend current techniques, using the larger events conventionally located as master events to define wavefield templates for mapping normally-discarded indistinct seismicity. Since

  5. Geochemical studies of the geothermal systems in Kenya: II. The Majimoto geothermal field

    NASA Astrophysics Data System (ADS)

    Tole, Mwakio P.

    1992-04-01

    The Majimoto geothermal field discharges at the boundary between metamorphic schists and gneisses of Precambrian age, and Pleistocene volcanic ashes. The waters are near neutral, low salinity waters. Calculated reservoir temperatures are about 90°C. Oxygen and hydrogen isotopes indicate that the thermal waters are meteoric in origin. The field is suitable for development for uses in spa therapy, crop drying, milk pasteurisation, leather processing and house warming.

  6. Structural controls of the Tuscarora geothermal field, Elko County, Nevada

    NASA Astrophysics Data System (ADS)

    Dering, G.; Faulds, J. E.

    2012-12-01

    Tuscarora is an amagmatic geothermal system located ~90 km northwest of Elko, Nevada, in the northern part of the Basin and Range province ~15 km southeast of the Snake River Plain. Detailed geologic mapping, structural analysis, and well data have been integrated to identify the structural controls of the Tuscarora geothermal system. The structural framework of the geothermal field is defined by NNW- to NNE-striking normal faults that are approximately orthogonal to the present extension direction. Boiling springs, fumaroles, and siliceous sinter emanate from a single NNE-striking, west-dipping normal fault. Normal faults west of these hydrothermal features mostly dip steeply east, whereas normal faults east of the springs primarily dip west. Thus, the springs, fumaroles, and sinter straddle a zone of interaction between fault sets that dip toward each other, classified as a strike-parallel anticlinal accommodation zone. Faults within the geothermal area are mostly discontinuous along strike with offsets of tens to hundreds of meters, whereas the adjacent range-bounding fault systems of the Bull Run and Independence Mountains accommodate several kilometers of displacement. The geothermal field lies within a broad step over between the southward terminating west-dipping Bull Run fault zone and the northward terminating west-dipping Independence Mountains fault zone. Neither of these major fault zones is known to host high temperature geothermal systems. The accommodation zone lies within the broad step over and contains both east-dipping antithetic and west-dipping synthetic faults. Accommodation zones are relatively common structural components of extended terranes that transfer strain between oppositely dipping fault sets via a network of subsidiary normal faults. This study has identified the hinge zone of an anticlinal accommodation zone as the site most conducive to fluid up-flow. The recognition of this specific portion of an accommodation zone as a favorable

  7. The Hydrogeochemistry of Qingshui Geothermal Field, Northeastern Taiwan.

    NASA Astrophysics Data System (ADS)

    Yu-Wen, Chen; Cheng-Kuo, Lin; Wayne, Lin; Yu-Te, Chang; Pei-Shan, Hsieh

    2015-04-01

    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

  8. Measurement of Subsidence in the Yangbajain Geothermal Fields from TerraSAR-X

    NASA Astrophysics Data System (ADS)

    Li, Yongsheng; Zhang, Jingfa; Li, Zhenhong

    2016-08-01

    Yangbajain contains the largest geothermal energy power station in China. Geothermal explorations in Yangbajain first started in 1976, and two plants were subsequently built in 1981 and 1986. A large amount of geothermal fluids have been extracted since then, leading to considerable surface subsidence around the geothermal fields. In this paper, InSAR time series analysis is applied to map the subsidence of the Yangbajain geothermal fields during the period from December 2011 to November 2012 using 16 senses of TerraSAR-X stripmap SAR images. Due to its high resolution and short repeat cycle, TerraSAR-X provides detailed surface deformation information at the Yangbajain geothermal fields.

  9. Deep geothermal processes acting on faults and solid tides in coastal Xinzhou geothermal field, Guangdong, China

    NASA Astrophysics Data System (ADS)

    Lu, Guoping; Wang, Xiao; Li, Fusi; Xu, Fangyiming; Wang, Yanxin; Qi, Shihua; Yuen, David

    2017-03-01

    This paper investigated the deep fault thermal flow processes in the Xinzhou geothermal field in the Yangjiang region of Guangdong Province. Deep faults channel geothermal energy to the shallow ground, which makes it difficult to study due to the hidden nature. We conducted numerical experiments in order to investigate the physical states of the geothermal water inside the fault zone. We view the deep fault as a fast flow path for the thermal water from the deep crust driven up by the buoyancy. Temperature measurements at the springs or wells constrain the upper boundary, and the temperature inferred from the Currie temperature interface bounds the bottom. The deepened boundary allows the thermal reservoir to revolve rather than to be at a fixed temperature. The results detail the concept of a thermal reservoir in terms of its formation and heat distribution. The concept also reconciles the discrepancy in reservoir temperatures predicted from both quartz and Na-K-Mg. The downward displacement of the crust increases the pressure at the deep ground and leads to an elevated temperature and a lighter water density. Ultimately, our results are a first step in implementing numerical studies of deep faults through geothermal water flows; future works need to extend to cases of supercritical states. This approach is applicable to general deep-fault thermal flows and dissipation paths for the seismic energy from the deep crust.

  10. Numerical model of the Amiata Volcano geothermal fields, Italy

    NASA Astrophysics Data System (ADS)

    Allocca, Carmine; Borgia, Andrea; Filippo Michele, Di

    2013-04-01

    The Amiata geothermal fields form an annulus all around the Northeastern (Poggio Zoccolino field), Southeastern (Piancastagnaio field), Southern (Poggio al Nibbio field) and Southwestern (Bagnore field) base of the volcano. The fields, first exploited between the 1950s and the 1960s, produced an incondensable-gas rich fluid, which later evolved to become vapour-dominated. During the first years of geothermal exploitation, the pressure of the fields dropped from 40-50 bars (at Piancastagnaio) and 20-25 bars (at Bagnore) to about 20 bars and 5 bars, respectively. Depressurization of these fields induced the drainage of the freshwater aquifer contained in the volcanic rocks, a substantial drop of its water-table and a decrease in springs flow rates. Our work aims at modelling the hydrothermal system of the Amiata Volcano and the development of the geothermal fields. We use the TOUGH2 poly-phase , multi-component thermal porous-media flow code developed at LBNL, as implemented by the GUI Petrasim™, with the ESWAG equation of state. Our model is based on geological, geophysical and geochemical data made public during the past 50 years in addition to work published in scientific journals. It represent an area of 32 x 36 km2 with cells of 1*1 km; the model extends 6.65 km in depth and is divided in 58 layers that increase from 50 m thick at the surface to 400 m at depth for a total of about 48.000 cells. Although the geology of the model is necessarily simplified, it retains the characteristic topology and structure found in the field. Our results show that the hot fluids rising below the volcano become diverted outward by the fresh water of the volcanic aquifer that recharges the hydrothermal system at its centre. This topology of the hydrothermal system correctly reproduces the location of the geothermal fields and results in a superficial temperature gradient that is comparable to the measured one. At the base of the volcano, the incondensable gases (mainly CO2

  11. Temperature distribution in the Cerro Prieto geothermal field

    SciTech Connect

    Castillo B, F.; Bermejo M, F.J.; Domiguez A, B.; Esquer P, C.A.; Navarro O, F.J.

    1981-01-01

    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.

  12. Geothermal Field Near Rotorua, New Zealand

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Historical sketches show the indigenous Maori cooking with natural hot waters and steam prior to the arrival of Europeans on North Island, New Zealand. Since the 1950s, geothermal heat and steam have been exploited for both heating and electrical power generation, and some excess electrical power is exported to South Island. The geothermal development can be identified by the unique patterns of infrastructure that look like tan beads on a string in the midst of otherwise green vegetation. This one near the town of Rotorua lies within a northeast-trending line of active volcanoes (Ruapehu, Tongariro, and White Island) that are the surface result of the Pacific tectonic plate descending beneath the Australian-Indian plate. Image STS110-726-10 was taken by space shuttle crewmembers in April 2002 using a Hasselblad film camera. Image provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  13. Geothermal Field Near Rotorua, New Zealand

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Historical sketches show the indigenous Maori cooking with natural hot waters and steam prior to the arrival of Europeans on North Island, New Zealand. Since the 1950s, geothermal heat and steam have been exploited for both heating and electrical power generation, and some excess electrical power is exported to South Island. The geothermal development can be identified by the unique patterns of infrastructure that look like tan beads on a string in the midst of otherwise green vegetation. This one near the town of Rotorua lies within a northeast-trending line of active volcanoes (Ruapehu, Tongariro, and White Island) that are the surface result of the Pacific tectonic plate descending beneath the Australian-Indian plate. Image STS110-726-10 was taken by space shuttle crewmembers in April 2002 using a Hasselblad film camera. Image provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  14. Structural Controls of the Tuscarora Geothermal Field, Elko County, Nevada

    NASA Astrophysics Data System (ADS)

    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

  15. Spatial analysis of respiratory disease on an urbanized geothermal field.

    PubMed

    Durand, Michael; Wilson, J Gaines

    2006-06-01

    Chronic exposure to hydrogen sulfide (H(2)S) in the parts per billion-parts per million range occurs in the population of Rotorua, a city built upon an actively degassing geothermal field in the Taupo Volcanic Zone, New Zealand. H(2)S is acutely toxic at high concentrations but little is understood of the health effects of chronic, low-level exposure. In Rotorua, H(2)S emissions and ambient concentrations are heterogeneous and approximately 30% of the greater urban area's population live upon or <4 km downwind of the geothermal field. Spatial analysis of disease incidence clustering using a spatial scan statistic is a powerful tool with which to investigate the spatial relationship which may exist between H(2)S and respiratory disease. This paper reports findings from a spatial cluster analysis of 11 years of hospital discharge data at the census area unit resolution. Results indicate that the relative risk (RR) of incidence of noninfectious respiratory diseases may be substantially higher among residents living in the geothermal area than have been reported previously. RR >5 for chronic obstructive pulmonary disease and its associated conditions are found in clusters which are spatially coincident with the geothermal field. Future work which investigates neurological and circulatory disease groups at the same or better spatial resolution may provide further insight into the chronic health effects of H(2)S exposure than these preliminary findings indicate.

  16. Relative Contributions of Geothermal Pumping and Long-Term Earthquake Rate to Seismicity at California Geothermal Fields

    NASA Astrophysics Data System (ADS)

    Weiser, D. A.; Jackson, D. D.

    2015-12-01

    In a tectonically active area, a definitive discrimination between geothermally-induced and tectonic earthquakes is difficult to achieve. We focus our study on California's 11 major geothermal fields: Amedee, Brawley, Casa Diablo, Coso, East Mesa, The Geysers, Heber, Litchfield, Salton Sea, Susanville, and Wendel. The Geysers geothermal field is the world's largest geothermal energy producer. California's Department of Oil Gas and Geothermal Resources provides field-wide monthly injection and production volumes for each of these sites, which allows us to study the relationship between geothermal pumping activities and seismicity. Since many of the geothermal fields began injecting and producing before nearby seismic stations were installed, we use smoothed seismicity since 1932 from the ANSS catalog as a proxy for tectonic earthquake rate. We examine both geothermal pumping and long-term earthquake rate as factors that may control earthquake rate. Rather than focusing only on the largest earthquake, which is essentially a random occurrence in time, we examine how M≥4 earthquake rate density (probability per unit area, time, and magnitude) varies for each field. We estimate relative contributions to the observed earthquake rate of M≥4 from both a long-term earthquake rate (Kagan and Jackson, 2010) and pumping activity. For each geothermal field, respective earthquake catalogs (NCEDC and SCSN) are complete above at least M3 during the test period (which we tailor to each site). We test the hypothesis that the observed earthquake rate at a geothermal site during the test period is a linear combination of the long-term seismicity and pumping rates. We use a grid search to determine the confidence interval of the weighting parameters.

  17. Seismic Activity at tres Virgenes Volcanic and Geothermal Field

    NASA Astrophysics Data System (ADS)

    Antayhua, Y. T.; Lermo, J.; Quintanar, L.; Campos-Enriquez, J. O.

    2013-05-01

    The volcanic and geothermal field Tres Virgenes is in the NE portion of Baja California Sur State, Mexico, between -112°20'and -112°40' longitudes, and 27°25' to 27°36' latitudes. Since 2003 Power Federal Commission and the Engineering Institute of the National Autonomous University of Mexico (UNAM) initiated a seismic monitoring program. The seismograph network installed inside and around the geothermal field consisted, at the beginning, of Kinemetrics K2 accelerometers; since 2009 the network is composed by Guralp CMG-6TD broadband seismometers. The seismic data used in this study covered the period from September 2003 - November 2011. We relocated 118 earthquakes with epicenter in the zone of study recorded in most of the seismic stations. The events analysed have shallow depths (≤10 km), coda Magnitude Mc≤2.4, with epicentral and hypocentral location errors <2 km. These events concentrated mainly below Tres Virgenes volcanoes, and the geothermal explotation zone where there is a system NW-SE, N-S and W-E of extensional faults. Also we obtained focal mechanisms for 38 events using the Focmec, Hash, and FPFIT methods. The results show normal mechanisms which correlate with La Virgen, El Azufre, El Cimarron and Bonfil fault systems, whereas inverse and strike-slip solutions correlate with Las Viboras fault. Additionally, the Qc value was obtained for 118 events. This value was calculated using the Single Back Scattering model, taking the coda-waves train with window lengths of 5 sec. Seismograms were filtered at 4 frequency bands centered at 2, 4, 8 and 16 Hz respectively. The estimates of Qc vary from 62 at 2 Hz, up to 220 at 16 Hz. The frequency-Qc relationship obtained is Qc=40±2f(0.62±0.02), representing the average attenuation characteristics of seismic waves at Tres Virgenes volcanic and geothermal field. This value correlated with those observed at other geothermal and volcanic fields.

  18. Volume strain within the Geysers geothermal field

    SciTech Connect

    Mossop, Antony; Segall, Paul

    1999-12-10

    During the 1970s and 1980s. The Geysers geothermal region was rapidly developed as a site of geothermal power production. The likelihood that this could cause significant strain within the reservoir, with corresponding surface displacements, led to a series of deformation monitoring surveys. In 1973, 1975, 1977, and 1980, The Geysers region was surveyed using first-order, class I, spirit leveling. In 1994, 1995, and 1996, many of the leveling control monuments were resurveyed using high-precision Global Positioning System receivers. The two survey methods are reconciled using the GEOID96 geoid model. The displacements are inverted to determine volume strain within the reservoir. For the period 1980-1994, peak volume strains in excess of 5x10{sup -4} are imaged. There is an excellent correlation between the observed changes in reservoir steam pressures and the imaged volume strain. If reservoir pressure changes are inducing volume strain, then the reservoir quasi-static bulk modulus K must be <4.6x10{sup 9} Pa. However, seismic velocities indicate a much stiffer reservoir with K=3.4x10{sup 10} Pa. This apparent discrepancy is shown to be consistent with predicted frequency dependence in K for fractured and water-saturated rock. Inversion of surface deformation data therefore appears to be a powerful method for imaging pressure change within the body of the reservoir. Correlation between induced seismicity at The Geysers and volume strain is observed. However, earthquake distribution does not appear to have a simple relationship with volume strain rate. (c) 1999 American Geophysical Union.

  19. Absence of remote earthquake triggering within the Coso and Salton Sea geothermal production fields

    NASA Astrophysics Data System (ADS)

    Zhang, Qiong; Lin, Guoqing; Zhan, Zhongwen; Chen, Xiaowei; Qin, Yan; Wdowinski, Shimon

    2017-01-01

    Geothermal areas are long recognized to be susceptible to remote earthquake triggering, probably due to the high seismicity rates and presence of geothermal fluids. However, anthropogenic injection and extraction activity may alter the stress state and fluid flow within the geothermal fields. Here we examine the remote triggering phenomena in the Coso geothermal field and its surrounding areas to assess possible anthropogenic effects. We find that triggered earthquakes are absent within the geothermal field but occur in the surrounding areas. Similar observation is also found in the Salton Sea geothermal field. We hypothesize that continuous geothermal operation has eliminated any significant differential pore pressure between fractures inside the geothermal field through flushing geothermal precipitations and sediments out of clogged fractures. To test this hypothesis, we analyze the pore-pressure-driven earthquake swarms, and they are found to occur outside or on the periphery of the geothermal production field. Therefore, our results suggest that the geothermal operation has changed the subsurface fracture network, and differential pore pressure is the primary controlling factor of remote triggering in geothermal fields.

  20. Ecological protection in the Las Tres Virgenes, Mexico, geothermal field

    SciTech Connect

    Zirahuen Ortega Varela, J.R.

    1996-12-31

    The programs of environmental protection designed by Comision Federal de Electricidad are described in a general way. These programs detect, avoid, soften and compensate the environmental impacts product of the exploration, construction and operation activities of the geothermal field Las Tres Virgenes, this field is in the buffer zone of the biosphere reserve {open_quotes}El Vizcaino{close_quotes} at the north of the State of Baja California Sur, Mexico.

  1. Subsidence and uplift at Heber Geothermal field, California

    SciTech Connect

    Boardman, T.S.

    1996-01-01

    Heber Geothermal field is in the Imperial Valley near the City of Heber, California, about 3 1/2 miles north of the Mexican border. The field is at the southern end of a network of irrigated agricultural fields extending across the valley floor. The Heber geothermal system is circular, producing water of moderate temperature (360{degrees}F) and low-salinity (13,000-14,000 ppm TDS). In cross section, the geothermal system resembles a lopsided mushroom. The system has three major permeability units: capping clays form 500 to 1800 feet; a high-matrix-permeability, deltaic-sandstone outflow reservoir from 1,800 to 5,500 feet; and feeder faults and fractures in indurated sediments below 5,500 feet. The deltaic sandstones were deposited by the ancestral Colorado River. As both power plants continue operating in Heber field, the need persists to monitor subsidence and uplift. The field`s subsidence bowl is not expected to expand significantly, but some small changes are expected due to pressure changes caused by production for the SIGC binary power plant. The three SIGC injection wells, located between the production areas for the two power plants, will be managed for adequate reservoir pressure support.

  2. Heat-flow mapping at the Geysers Geothermal Field

    SciTech Connect

    Thomas, R.P.

    1986-10-31

    Pertinent data were compiled for 187 temperature-gradient holes in the vicinity of The Geysers Geothermal field. Terrain-correction techniques were applied to most of the temperature-gradient data, and a temperature-gradient map was constructed. Cutting samples from 16, deep, production wells were analyzed for thermal conductivity. From these samples, the mean thermal conductivities were determined for serpentinized ultramafic rock, greenstone, and graywacke. Then, a heat flow map was made. The temperature-gradient and heat-flow maps show that The Geysers Geothermal field is part of a very large, northwesterly-trending, thermal anomaly; the commercially productive portion of the field may be 100 km/sup 2/ in area. The rate that heat energy flows through the surface by thermal conduction is estimated at 1.79 x 10/sup 9/MJ per year. The net heat energy loss from commercial production for 1983 is estimated at 180.14 x 10/sup 9/MJ.

  3. A Reservoir Assessment of the Geysers Geothermal Field

    SciTech Connect

    Thomas, Richard P.; Chapman, Rodger H.; Dykstra, Herman; Stockton, A.D.

    1981-01-01

    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)

  4. Geothermal well stimulation - program summary and the Beowawe field experiment

    SciTech Connect

    Verity, R.V.

    1983-12-01

    Republic Geothermal, Inc. and its subcontractors have planned and executed laboratory studies and eight well stimulation field experiments under the Geothermal Reservoir Well Stimulation Program (GRWSP). The program, begun in February 1979, has concentrated on extending petroleum industry stimulation technology for use by the geothermal industry. The most recent experiment was in a naturally fractured Chevron well at Beowawe and involved an acid stimulation of a damaged interval which yielded a 2.3-fold increase in injectivity. Overall results to date have shown that stimulation is viable where adequate reservoirs are penetrated by wells encountering formation damage or locally tight formations. However, wells in marginal naturally fractured reservoirs have not been saved by the types of well stimulation jobs performed thus far. A recent discovery is that many wells can possibly be made outstanding producers by widening and propping compliant natural fractures. Confirmation of this constitutes unfinished business of the GRWSP, adn offers one of the greatest potential opportunities for enhancing the economics of geothermal power production.

  5. An approach for geochemical assessment of Chipilapa geothermal field

    SciTech Connect

    Nieva, D.; Verma, M.P.; Portugal, E.; Torres, V.

    1993-01-28

    It presents a systematic methodology to evaluate the reservoir characteristics of Chipilapa- Ahuachapan geothermal field through the highly diluted natural manifestations (springs and domestic wells) in its surroundings. The manifestations are classified in three main groups according to their mechanism of formation: high salinity water (HSW), medium salinity water (MSW), and Sulfated Water (SW). The reservoir temperature at Chipilapa geothermal field is around 220°C which is estimated with application of various chemical geothermometers. The isotopic studies indicate that the heating of local meteoric water with the separated steam of deep reservoir fluids is a dominating process in the formation of springs and domestic wells fluids. The process of formation of primary and secondary vapor explains the isotopic composition of fumaroles.

  6. Some Comments on the La Primavera Geothermal Field, Mexico

    SciTech Connect

    A., Bernardo Dominguez; Lippmann, Marcelo J.

    1983-12-15

    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.

  7. Subsidence: Causes, Effects, and Mitigations in Geothermal Field

    NASA Astrophysics Data System (ADS)

    Sektiawan, Akta; Adi Prasetyo, Ganung; Patera Adli, Dida; Yuantoro, Ethis

    2016-09-01

    Subsidence is the motion of the ground surface as it moves down relatively. It can occur in a wide range of area. It is an impact of production of large mass and volume of saturation from the reservoir. It doesn't happen especially in geothermal fields only, but also in oil and gas industry. Large fluid volume production leads to the decrease of pore pressure inside reservoir. This decline disturbs the pressure stability and overburden pressure compress the pores. It results the drop in ground surface. The decrease in ground surface level induces a devastating effect in the construction of some facilities, such as building, pipeline, canal, and river. It may interrupt the balance in the ecosystems nearby. Good management and several survey methods (such as levelling and gravity) will reduce the risk of subsidence and the other effects related to it. This discussion output can be used as a guide for minimizing subsidence impact in the geothermal field in general.

  8. Hydrogeologic model of the Ahuachapan geothermal field, El Salvador

    SciTech Connect

    Laky, C.; Lippmann, M.J.; Bodvarsson, G.S. ); Retana, M.; Cuellar, G. )

    1989-01-01

    A hydrogeological model of the Ahuachapan geothermal field has been developed. It considers the lithology and structural features of the area and discerns their impact on the movement of cold and hot fluids in the system. Three aquifers were identified, their zones of mixing and flow patterns were obtained on the basis of temperature and geochemical data from wells and surface manifestations. 12 refs., 9 figs.

  9. Recency of Faulting and Neotechtonic Framework in the Dixie Valley Geothermal Field and Other Geothermal Fields of the Basin and Range

    SciTech Connect

    Steven Wesnousky; S. John Caskey; John W. Bell

    2003-02-20

    We studied the role that earthquake faults play in redistributing stresses within in the earths crust near geothermal fields. The geographic foci of our study were the sites of geothermal plants in Dixie Valley, Beowawe, and Bradys Hot Springs, Nevada. Our initial results show that the past history of earthquakes has redistributed stresses at these 3 sites in a manner to open and maintain fluid pathways critical for geothermal development. The approach developed here during our pilot study provides an inexpensive approach to (1) better define the best locations to site geothermal wells within known geothermal fields and (2) to define the location of yet discovered geothermal fields which are not manifest at the surface by active geothermal springs. More specifically, our investigation shows that induced stress concentrations at the endpoints of normal fault ruptures appear to promote favorable conditions for hydrothermal activity in two ways. We conclude that an understanding of the spatial distribution of active faults and the past history of earthquakes on those faults be incorporated as a standard tool in geothermal exploration and in the siting of future boreholes in existing geothermal fields.

  10. The Geysers Geothermal Field Update1990/2010

    SciTech Connect

    Brophy, P.; Lippmann, M.; Dobson, P.F.; Poux, B.

    2010-10-01

    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 view across

  11. Oil field geothermal waters of Wyoming

    SciTech Connect

    Hinckley, B.S.

    1983-08-01

    Over 150 million gallons of water a day are brought to the surface in the oil fields of Wyoming. The temperature of this water is nearly always greater than 90/sup 0/F, and ranges as high as 230/sup 0/F. The location, volume, temperature, and present use status of co-produced oil field thermal waters are presented briefly.

  12. Magnetotelluric Exploration of the Sipoholon Geothermal Field, Indonesia

    NASA Astrophysics Data System (ADS)

    Niasari, S. W.; Muñoz, G.; Kholid, M.; Suhanto, E.; Ritter, O.

    2012-04-01

    Magnetotelluric (MT) measurements have been carried out at 96 sites around the Sipoholon Geothermal field, in the province of North Sumatra, Indonesia. The Sipoholon geothermal field is a low enthalpy geothermal system located in a pull-apart basin controlled by the Sumatra fault system. One of the main difficulties in understanding this system is an apparently random distribution of temperatures in 15 hot springs in the area. High levels of electromagnetic noise with several high voltage power lines in a densely populated area is challenging for natural source MT measurements. Noise at long periods and in the dead band (1s to 10s) could be removed with robust remote reference processing and high frequency noise could be suppressed with a delay line filter. After dimensionality and directionality analysis of the data, we found a regional strike direction consistent with the Sumatra fault. We present results of 2D inversion of the data along several profiles perpendicular to the main strike direction. Modeling results indicate a shallow (< 1000 m) low resistivity layer, zones of high resistivity at intermediate depths (approximately 500 to 5000 m), and regions of low resistivity in the depth range of 2 to 4 km. These deep zones of low resistivity could be caused by hydrothermal alteration or hydrothermal fluids. The shallow low resistivity correlates spatially with the graben areas of the pull-apart system and is likely associated with (unconsolidated) sedimentary fill.

  13. Changes in thermal activity in the Rotorua geothermal field

    SciTech Connect

    Cody, A.D. ); Lumb, J.T. )

    1992-04-01

    During a period when geothermal fluid was being withdrawn for energy use at an increasing rate, the level of natural hydrothermal activity in the Rotorua geothermal field declined in an all-time low in the mid 1980s. total heatflow from a major hot-spring area fell by almost 50 percent, springs ceased their flow, and geysers displayed abnormal behavior consistent with a low aquifer pressure. since the enforced closure of bores within 1.5 km of Pohutu Geyser, sings of recovery, including a return to normal behavior of Pohutu and Waikorohihi Geysers, a resumption of activity at Kereru Geyser, and an increase in water flow from some springs are presented in this paper.

  14. Los Azufres geothermal field: Observed response after 12-year exploitation

    SciTech Connect

    Maldonado, G.J.

    1995-12-31

    Exploitation of the Los Azufres Geothermal field was initiated in August 1982, with the electric power generation of five 5-MW wellhead units. Since then another 70 MW have been installed. A large amount of information has been compiled, including geologic, geochemical, production, and reservoir characteristics. The data were evaluated to detect the extent of observable changes in the main reservoir parameters over the twelve-year production period. Pressure and temperature measurements in Los Azufres wells show that geothermal fluid distribution is strongly influenced by the presence of permeable structures. Wellhead production and chemical analysis of the separated brine show that we are dealing with a highly heterogeneous reservoir, were the drawdown and enthalpy changes depend on the position of the well being studied.

  15. Strain rate orientations near the Coso Geothermal Field

    NASA Astrophysics Data System (ADS)

    Ogasa, N. T.; Kaven, J. O.; Barbour, A. J.; von Huene, R.

    2016-12-01

    Many geothermal reservoirs derive their sustained capacity for heat exchange in large part due to continuous deformation of preexisting faults and fractures that permit permeability to be maintained. Similarly, enhanced geothermal systems rely on the creation of suitable permeability from fracture and faults networks to be viable. Stress measurements from boreholes or earthquake source mechanisms are commonly used to infer the tectonic conditions that drive deformation, but here we show that geodetic data can also be used. Specifically, we quantify variations in the horizontal strain rate tensor in the area surrounding the Coso Geothermal Field (CGF) by analyzing more than two decades of high accuracy differential GPS data from a network of 14 stations from the University of Nevada Reno Geodetic Laboratory. To handle offsets in the data, from equipment changes and coseismic deformation, we segment the data, perform a piecewise linear fit and take the average of each segment's strain rate to determine secular velocities at each station. With respect to North America, all stations tend to travel northwest at velocities ranging from 1 to 10 mm/yr. The nearest station to CGF shows anomalous motion compared to regional stations, which otherwise show a coherent increase in network velocity from the northeast to the southwest. We determine strain rates via linear approximation using GPS velocities in Cartesian reference frame due to the small area of our network. Principal strain rate components derived from this inversion show maximum extensional strain rates of 30 nanostrain/a occur at N87W with compressional strain rates of 37nanostrain/a at N3E. These results generally align with previous stress measurements from borehole breakouts, which indicate the least compressive horizontal principal stress is east-west oriented, and indicative of the basin and range tectonic setting. Our results suggest that the CGF represents an anomaly in the crustal deformation field, which

  16. Reservoir Studies of the Seltjarnarnes Geothermal Field, Iceland

    SciTech Connect

    Tulinius, H.; Spencer, A.L.; Bodvarsson, G.S.; Kristmannsdottir, H.; Thorsteinsson, T.; Sveinbjornsdottir, A.E.

    1987-01-20

    The Seltjarnarnes geothermal field in Iceland has been exploited for space heating for the last 16 years. A model of the field has been developed that integrates all available data. The model has been calibrated against the flow rate and pressure decline histories of the wells and the temperature and chemical changes of the produced fluids. This has allowed for the estimation of the permeability and porosity distribution of the system, and the volume of the hot reservoir. Predictions of future reservoir behavior using the model suggest small pressure and temperature changes, but a continuous increase in the salinity of the fluids produced. 10 figs., 23 refs.

  17. Hydrothermal surface alteration in the Copahue Geothermal Field (Argentina)

    SciTech Connect

    Mas, Graciela R.; Mas, Luis C.; Bengochea, Leandro

    1996-01-24

    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.

  18. Strategies and Perceptions of Students' Field Note-Taking Skills: Insights from a Geothermal Field Lesson

    ERIC Educational Resources Information Center

    Dohaney, Jacqueline; Brogt, Erik; Kennedy, Ben

    2015-01-01

    Field note-taking skills are fundamental in the geosciences but are rarely explicitly taught. In a mixed-method study of an introductory geothermal field lesson, we characterize the content and perceptions of students' note-taking skills to derive the strategies that students use in the field. We collected several data sets: observations of the…

  19. Strategies and Perceptions of Students' Field Note-Taking Skills: Insights from a Geothermal Field Lesson

    ERIC Educational Resources Information Center

    Dohaney, Jacqueline; Brogt, Erik; Kennedy, Ben

    2015-01-01

    Field note-taking skills are fundamental in the geosciences but are rarely explicitly taught. In a mixed-method study of an introductory geothermal field lesson, we characterize the content and perceptions of students' note-taking skills to derive the strategies that students use in the field. We collected several data sets: observations of the…

  20. Field testing advanced geothermal turbodrill (AGT). Phase 1 final report

    SciTech Connect

    Maurer, W.C.; Cohen, J.H.

    1999-06-01

    Maurer Engineering developed special high-temperature geothermal turbodrills for LANL in the 1970s to overcome motor temperature limitations. These turbodrills were used to drill the directional portions of LANL`s Hot Dry Rock Geothermal Wells at Fenton Hill, New Mexico. The Hot Dry Rock concept is to drill parallel inclined wells (35-degree inclination), hydraulically fracture between these wells, and then circulate cold water down one well and through the fractures and produce hot water out of the second well. At the time LANL drilled the Fenton Hill wells, the LANL turbodrill was the only motor in the world that would drill at the high temperatures encountered in these wells. It was difficult to operate the turbodrills continuously at low speed due to the low torque output of the LANL turbodrills. The turbodrills would stall frequently and could only be restarted by lifting the bit off bottom. This allowed the bit to rotate at very high speeds, and as a result, there was excessive wear in the bearings and on the gauge of insert roller bits due to these high rotary speeds. In 1998, Maurer Engineering developed an Advanced Geothermal Turbodrill (AGT) for the National Advanced Drilling and Excavation Technology (NADET) at MIT by adding a planetary speed reducer to the LANL turbodrill to increase its torque and reduce its rotary speed. Drilling tests were conducted with the AGT using 12 1/2-inch insert roller bits in Texas Pink Granite. The drilling tests were very successful, with the AGT drilling 94 ft/hr in Texas Pink Granite compared to 45 ft/hr with the LANL turbodrill and 42 ft/hr with a rotary drill. Field tests are currently being planned in Mexico and in geothermal wells in California to demonstrate the ability of the AGT to increase drilling rates and reduce drilling costs.

  1. Reservoir and hydrogeochemical characterizations of geothermal fields in Salihli, Turkey

    NASA Astrophysics Data System (ADS)

    Özen, Tuğbanur; Bülbül, Ali; Tarcan, Gültekin

    2012-10-01

    Geothermal and hydrochemical characteristics of thermal waters in the Salihli geothermal area are described in this study. This geothermal area is geographically divided into five main groups; Kurşunlu, Caferbey, Greenhouse, Üfürük and Sart geothermal fields. In the study area, the outlet temperatures of the thermal waters are between 30 and 90 °C, their discharges are between 2 and 80 l/s in springs and the depths of wells vary between 200 and 1189 m. Hydrochemical analysis results suggest four different water types of Na-HCO3, Ca-Mg-HCO3, Ca-Na-HCO3 and Ca-Mg-SO4 in Kurşunlu, Caferbey-Greenhouse, Sart, and Üfürük, respectively. Cold waters are mainly dominated by the HCO3 and SO4 anions and Na, Ca, and Mg cations. Results of environmental isotope and chemical analysis show that the thermal waters are of meteoric origin and the major hydrogeochemical processes show that the thermal waters may be mixing of their end members and/or water-rock interaction at high temperature conditions. The mixed thermal waters are replenished by rainwater and/or groundwater at various depths. EC-tritium and EC-chloride plots indicated shallow and deep circulating groundwater types in the study area. Assessment of the various empirical chemical geothermometers and geochemical modelling suggests that the aquifer temperature in the study area is about 160 °C. The thermal waters are mostly supersaturated with respect to carbonate minerals (calcite, aragonite, and dolomite) at all temperatures. These are likely to cause scaling problems during production and utilization of thermal water.

  2. Seismicity and coupled deformation modeling at the Coso Geothermal Field

    NASA Astrophysics Data System (ADS)

    Kaven, J. O.; Hickman, S. H.; Davatzes, N. C.

    2015-12-01

    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.

  3. Gas geochemistry of the Geysers geothermal field

    SciTech Connect

    Truesdell, A.H.

    1993-04-01

    Increases in gas concentrations in Central and Southeast Geysers steam are related to the decreases in pressure caused by heavy exploitation in the 1980s. When reservoir pressures in the central parts of the field decreased, high-gas steam from undrilled reservoir margins (and possibly from underlying high-temperature zones) flowed into exploited central areas. The Northwest Geysers reservoir probably lacks high-gas marginal steam and a decline in pressure may not cause a significant increase of gas concentrations in produced steam.

  4. Using a new Geothermal Well Field as a Field Laboratory to Facilitate Comprehensive Knowledge

    NASA Astrophysics Data System (ADS)

    Neumann, K.; Dowling, C. B.

    2011-12-01

    In Fall 2010, the faculty of the Department of Geological Sciences at Ball State University (BSU) took advantage of several recently drilled monitoring wells within BSU's newly constructed ground-source geothermal well field, currently the largest in the U.S., to create an undergraduate field laboratory for hydrogeological experiments. Using the Investigative Case-Based Learning approach, upper-level undergraduate students developed research projects that would assist BSU's Facilities in evaluating and maintaining the geothermal fields. The students designed original hypotheses and explored how to test them with the available equipment within one semester. They focused on observing and measuring the potential impact of the geothermal well field on groundwater temperature and flow direction using two shallow monitoring wells in gravel (~30 ft) and eight deeper monitoring wells in limestone (~70 ft). The results will be used for comparisons when the geothermal plant goes online in Fall 2011. Undergraduate and graduate students will perform experiments throughout this initial period and continue even after the geothermal field is activated. Through the use of different assessment tools, including peer evaluation, instructors' assessment and an assessment of understanding, we determined that twenty-five percent of the class gained full comprehensive understanding. These students were able to design new experiments by assessing their semester data, integrating their knowledge from previous classes, and synthesizing new hypotheses. The majority of the class was able to further expand their understanding of the scientific process, but not to the extent as the top students.

  5. Natural polarization studies at Balcova geothermal field

    SciTech Connect

    Ercan, A.; Drahor, M.; Atasoy, E.

    1986-06-01

    Contrasting resistivity, temperature, pressure, porosity and fluid migrations are the main causes of ion accumulations along the discontinuities which create coupling-induced natural current flow which is observed as the Natural Polarization Potential (NPP) on the surface. Natural Polarization Electric Field (NPE) variations were recorded along 13 profiles about 2.5 km each in a north-south direction. Interpretation of the coincident anomalies of the NPP and the NPE field resulted in determination of the polarization angle, polarization focal depth and the azimuths of the polarized interfaces. Considerable agreement between faults delineated by previous geological and geophysical investigations and polarization discontinuities was observed. The polarization plane was observed to be horizontal in high temperature areas but steepened gradually in relatively colder regions in the northern costal area. From the polarization depth distribution two depression zones were observed, separated by an uplifted section elongated in a north-south direction. The basin at the eastern side had an estimated polarization depth of 1.1 km and was limited by the Agamemnon-2 and -1 faults, while the western basin had an estimated depth of 1.3 km and extended in the east-west direction not previously reported. The eastern basin extends on the north side around the town of Inciralti, the western basin appeared to be elongated towards the town of Cesme.

  6. A database for The Geysers geothermal field

    SciTech Connect

    Bodvarsson, G.S.; Cox, B.L.; Fuller, P.; Ripperda, M.; Tulinius, H.; Witherspoon, P.A.; Goldstein, N.; Flexser, S.; Pruess, K. ); Truesdell, A. )

    1989-09-01

    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.

  7. Fractal analysis of pressure transients in the Geysers Geothermal Field

    SciTech Connect

    Acuna, J.A.; Ershaghi, I.; Yortsos, Y.C.

    1992-01-01

    The conventionally accepted models for the interpretation of pressure transient tests in naturally fractured reservoirs usually involve simplistic assumptions regarding the geometry and transport properties of the fractured medium. Many single well tests in this type of reservoirs fail to show the predicted behavior for dual or triple porosity or permeability systems and cannot be explained by these models. This paper describes the application of a new model based on a fractal interpretation of the fractured medium. The approach, discussed elsewhere [2], [6], is applied to field data from The Geysers Geothermal Field. The objective is to present an alternative interpretation to well tests that characterizes the fractured medium in a manner more consistent with other field evidence. The novel insight gained from fractal geometry allows the identification of important characteristics of the fracture structure that feeds a particular well. Some simple models are also presented that match the field transient results.

  8. Reservoir simulation studies on the Cerro Prieto geothermal field

    SciTech Connect

    Castaneda, M.; Abril, A.; Arellano, V.; Marquez, R.

    1982-01-01

    A reservoir engineering and simulation study is being carried out on the Cerro Prieto geothermal field. A preliminary material balance has been applied to the old part of this field. A single block with constant properties in the horizontal direction was used for this preliminary material balance. The vertical block column was subdivided in several levels in order to take into account the known lithologic column. From existing pressure and enthalpy field histories, a single phase (liquid) reservoir assumption was selected. Under this assumption, a lateral radial recharge was considered in obtaining the pressure and enthalpy history match. These preliminary results indicate that another type of recharge is probably taking place in this part of the field, rather than lateral radial.

  9. The Ngatamariki Geothermal Field, NZ: Surface Manifestations - Past and Present

    SciTech Connect

    Brotheridge, J.M.A.; Browne, P.R.L.; Hochstein, M.P.

    1995-01-01

    The Ngatamariki geothermal field, located 7 km south of Orakeikorako, discharges dilute chloride-bicarbonate waters of almost neutral pH from springs mostly on the margins of the field. Rhyolite tuffs in the northwestern part of the field are weakly silicified, probably due to their having reacted with heated groundwaters. Sinter deposits are common at Ngatamariki but are mostly relict from former activity. In 1994, the natural heat loss from the field was 30 {+-} 5 MW{sub thermal}. There has been a shift of thermal activity southward over the past 60 years; the changes were recognized by comparing air photographs taken in 1941 and 1991. In 1948, a hydrothermal eruption deposited breccia around its crater, which is now occupied by a pool at 52.5 C. Another pool at 88 C, first noticed in 1993, deposits a mixture of silica and calcite.

  10. Hydrogeochemistry and reservoir model of Fuzhou geothermal field, China

    NASA Astrophysics Data System (ADS)

    Huang, H. F.; Goff, Fraser

    1986-03-01

    Fuzhou geothermal field is a low- to intermediate-temperature geothermal system consisting of meteoric water that circulates deeply along faults. The area of the field is about 9 km 2 but it is elongated in a NNW-trending direction. Fluids in the field are controlled by a series of four NNW extensional faults in Cretaceous granitic basement (Fuzhou fault zone). These faults feed warm waters into overlying permeable Quaternary sediments. The hydrothermal system consists of north and south parts whose chemical compositions are subtly different. In the northern part the system discharges sulfate/chloride waters with relatively low chloride concentrations, but in the south the system discharges chloride waters having relatively high chloride concentrations. Maximum wellhead temperatures are 97°C, which agrees with the chalcedony geothermometer in many cases. Based on the solubility of quartz, the deep-reservoir temperature cannot exceed 123 to 131°C. From heat and mass balance calculations, we conclude that the present total extracted capacity of fluid from the reservoir (20,000 tons/day) could be doubled without noticeable drawdown. We estimate the recoverable heat in the reservoir to be about 1.71 × 10 11 MJ.

  11. Development of a geothermal resource in a fractured volcanic formation: Case study of the Sumikawa Geothermal Field, Japan

    SciTech Connect

    Garg, S.K.; Pritchett, J.W.; Stevens, J.L.; Luu, L.; Combs, J.

    1996-11-01

    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.

  12. Fracture patterns in graywacke outcrops at The Geysers geothermal field

    SciTech Connect

    Sammis, Charles G.; Lin Ji An; Ershaghi, I.

    1991-01-01

    The Geysers geothermal field covers an area of more than 35,000 acres and represents one of the most significant steam fields in the world. The heterogeneous nature of the reservoir, its fracture network and non-sedimentary rock distinguish it from ordinary sandstone reservoirs in terms of reservoir definition and evaluation (Stockton et al. 1984). Analysis of cuttings, record of steam entries, temperature and pressure surveys and spinner logs have contributed to an understanding of the subsurface geology and rock characteristics of the Geysers. Few conventional electrical log data are available for the main body of the reservoir. It is generally believed that while the fractures are the main conducts for fluid transport through the reservoirs, tight rocks between the major fractures contain the bulk of the fluid reserves. No independent measurement of liquid and vapor saturation can be made from the existing downhole tools. Pressure depletion in The Geysers geothermal field has become a major concern to the operators and utility companies in recent years. Plans for further development activities and future field management are contingent upon accurate computer modeling and definition of the field. The primary issues in reliable characterization of The Geysers field are the role of the rock matrix in holding liquid reserves and providing pressure support, the nature of fracture network, extent of liquid saturation in the reservoirs and injection pattern strategies to maximize heat recovery. Current modeling of The Geysers field is done through the use of general purpose geothermal reservoir simulators. Approaches employed include treating the reservoir as a single porosity equivalent or a dual porosity system. These simulators include formulation to represent transport of heat, steam and water. Heterogeneities are represented by spatial variations in formation or fracture permeability-thickness product, porosity or fluid saturations. Conceptual models based on dual

  13. Modeling of geothermal reservoirs: Fundamental processes, computer simulation, and field applications

    SciTech Connect

    Pruess, K.

    1988-09-01

    This article attempts to critically evaluate the present state of the art of geothermal reservoir simulation. Methodological aspects of geothermal reservoir modeling are briefly reviewed, with special emphasis on flow in fractured media. Then we examine applications of numerical simulation to studies of reservoir dynamics, well test design and analysis, and modeling of specific fields. Tangible impacts of reservoir simulation technology on geothermal energy development are pointed out. We conclude with considerations on possible future developments in the mathematical modeling of geothermal fields. 45 refs., 4 figs., 2 tabs.

  14. Distribution of geothermal fields on the Juan De Fuca ridge

    SciTech Connect

    Crane, K.; Aikman F. III; Embley, R.; Hammond, S.; Malahoff, A.; Lupton, J.

    1985-01-10

    Near bottom water temperatures were mapped along 400 km of the strike of the Juan de Fuca Ridge as part of a combined Sea MARC/Seabeam experiment to image the variability of morphology and structure along a spreading center segment. The water temperature data collected by a continuously towed thermistor chain, in addition to salinity data, indicate that there are four geothermal areas spaced at distances of 100 km from each other south of the Cobb propagator and one field just to the north of the propagator on the Endeavor Ridge segment. Each thermal region is located above a morphological dome on the spreading center. These domes are an average of 100--200 m shallower than the rest of the axis. The structure of bottom water suggests that the geothermal regions are on average 20 km long and that the heat from these fields raises the temperature in the water column by a minimum of 0.06/sup 0/C up to 300 m above the bottom. Two simple models are used to estimate the heat flux associated with these features.

  15. Origin of first cells at terrestrial, anoxic geothermal fields.

    PubMed

    Mulkidjanian, Armen Y; Bychkov, Andrew Yu; Dibrova, Daria V; Galperin, Michael Y; Koonin, Eugene V

    2012-04-03

    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(+), Zn(2+), Mn(2+), 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, CO(2)-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(+), Zn(2+), and phosphorous compounds.

  16. Shear velocity of the Rotokawa geothermal field using ambient noise

    NASA Astrophysics Data System (ADS)

    Civilini, F.; Savage, M. K.; Townend, J.

    2014-12-01

    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.

  17. Modeling discharge requirements for deep geothermal wells at the Cerro Prieto geothermal field, MX

    SciTech Connect

    Menzies, Anthony J.; Granados, Eduardo E.; Puente, Hector Gutierrez; Pierres, Luis Ortega

    1995-01-26

    During the mid-l980's, Comision Federal de Electricidad (CFE) drilled a number of deep wells (M-200 series) at the Cerro Prieto geothermal field, Baja California, Mexico to investigate the continuation of the geothermal reservoir to the east of the Cerro Prieto-II and III production areas. The wells encountered permeability at depths ranging from 2,800 to 4,400 m but due to the reservoir depth and the relatively cold temperatures encountered in the upper 1,000 to 2,000 m of the wells, it was not possible to discharge some of the wells. The wells at Cerro Prieto are generally discharged by injecting compressed air below the water level using 2-3/8-inch tubing installed with either a crane or workover rig. The objective of this technique is to lift sufficient water out of the well to stimulate flow from the reservoir into the wellbore. However, in the case of the M-200 series wells, the temperatures in the upper 1,000 to 2,000 m are generally below 50 C and the heat loss to the formation is therefore significant. The impact of heat loss on the stimulation process was evaluated using both a numerical model of the reservoir/wellbore system and steady-state wellbore modeling. The results from the study indicate that if a flow rate of at least 300 liters/minute can be sustained, the well can probably be successfully stimulated. This is consistent with the flow rates obtained during the successful stimulations of wells M-202 and M-203. If the flow rate is closer to 60 liters/minute, the heat loss is significant and it is unlikely that the well can be successfully discharged. These results are consistent with the unsuccessful discharge attempts in wells M-201 and M-205.

  18. Reservoir engineering studies of the Cerro Prieto geothermal field

    NASA Astrophysics Data System (ADS)

    Goyal, K. P.; Lippmann, M. J.; Tsang, C. F.

    1982-09-01

    Reservoir engineering studies of the Cerro Prieto geothermal field began in 1978 under a five-year cooperative agreement between the US Department of Energy and the Comision Federal de Electricidad de Mexico, with the ultimate objective of simulating the reservoir to forecast its production capacity, energy longevity, and recharge capability under various production and injection scenarios. During the fiscal year 1981, attempts were made to collect information on the evolution history of the field since exploitation began; the information is to be used later to validate the reservoir model. To this end, wellhead production data were analyzed for heat and mass flow and also for changes in reservoir pressures, temperatures, and saturations for the period from March 1973 to November 1980.

  19. Geochemical evidence of drawdown in the Cerro Prieto geothermal field

    USGS Publications Warehouse

    Truesdell, A.H.; Manon, M.A.; Jimenez, S.M.E.; Sanchez, A.A.; Fausto, L.J.J.

    1979-01-01

    Some wells of the Cerro Prieto geothermal field have undergone changes in the chemistry of fluids produced which reflect reservoir processes. Pressure decreases due to production in the southeastern part of the field have produced both drawdown of lower chloride fluids from an overlying aquifer and boiling in the aquifer with excess steam reaching the wells. These reservoir changes are indicated by changes in fluid chloride concentrations, Na/K ratios and measured enthalpies and by comparisons of aquifer fluid temperatures and chloride concentrations calculated from enthalpy and chemical measurements. Fluid temperatures have not been greatly affected by this drawdown because heat contained in the rock was transferred to the fluid. When this heat is exhausted, fluid temperatures may drop rapidly. ?? 1979.

  20. Sources of subsidence at the Salton Sea Geothermal Field

    USGS Publications Warehouse

    Barbour, Andrew J.; Evans, Eileen; Hickman, Stephen H.; Eneva, Mariana

    2016-01-01

    At the Salton Sea Geothermal Field (SSGF) in Southern California, surface deformation associated with geologic processes including sediment compaction, tectonic strain, and fault slip may be augmented by energy production activities. Separating the relative contributions from natural and anthropogenic sources is especially important at the SSGF, which sits at the apex of a complex tectonic transition zone connecting the southern San Andreas Fault with the Imperial Fault; but this has been a challenging task so far. Here we analyze vertical surface velocities obtained from the persistent scatterer InSAR method and find that two of the largest subsidence anomalies can be represented by a set of volumetric strain nuclei at depths comparable to geothermal well completion zones. In contrast, the rates needed to achieve an adequate fit to the magnitudes of subsidence are almost an order of magnitude greater than rates reported for annual changes in aggregate net-production volume, suggesting that the physical mechanism responsible for subsidence at the SSGF is a complicated interplay between natural and anthropogenic sources.

  1. Exploration and development of the Cerro Prieto geothermal field

    SciTech Connect

    Lippmann, M.J.; Goldstein, N.E.; Halfman, S.E.; Witherspoon, P.A.

    1983-10-01

    A multidisciplinary effort to locate, delineate, and characterize the geothermal system at Cerro Prieto, Baja California, Mexico, began about 25 years ago. It led to the identification of an important high-temperature, liquid-dominated geothermal system which went into production in 1973. Initially, the effort was undertaken principally by the Mexican electric power agency, the Comision Federal de Electricidad (CFE). Starting in 1977 a group of U.S. organizations sponsored by the U.S. Department of Energy, joined CFE in this endeavor. An evaluation of the different studies carried out at Cerro Prieto has shown that: surface electrical resistivity and seismic reflection surveys are useful in defining targets for exploratory drilling; the mineralogical studies of cores and cuttings and the analysis of well logs are important in designing the completion of wells, identifying geological controls on fluid movement, determining thermal effects and inferring the thermal history of the field; geochemical surveys help to define zones of recharge and paths of fluid migration; and reservoir engineering studies are necessary in establishing the characteristics of the reservoir and in predicting its response to fluid production.

  2. Exploration and development of the Cerro Prieto geothermal field

    SciTech Connect

    Lippmann, M.J.; Goldstein, N.E.; Halfman, S.E.; Witherspoon, P.A.

    1983-07-01

    A multidisciplinary effort to locate, delineate, and characterize the geothermal system at Cerro Prieto, Baja California, Mexico, began about 25 years ago. It led to the identification of an important high-temperature, liquid-dominated geothermal system which went into production in 1973. Initially, the effort was undertaken principally by the Mexican electric power agency, the Comision Federal de Electricidad (CFE). Starting in 1977 a group of US organizations sponsored by the US Department of Energy, joined CFE in this endeavor. An evaluation of the different studies carried out at Cerro Prieto has shown that: (1) surface electrical resistivity and seismic reflection surveys are useful in defining targets for exploratory drilling; (2) the mineralogical studies of cores and cuttings and the analysis of well logs are important in designing the completion of wells, identifying geological controls on fluid movement, determining thermal effects and inferring the thermal history of the field; (3) geochemical surveys help to define zones of recharge and paths of fluid migration; and (4) reservoir engineering studies are necessary in establishing the characteristics of the reservoir and in predicting its response to fluid production.

  3. Geothermal injection treatment: process chemistry, field experiences, and design options

    SciTech Connect

    Kindle, C.H.; Mercer, B.W.; Elmore, R.P.; Blair, S.C.; Myers, D.A.

    1984-09-01

    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.

  4. A reservoir engineering assessment of the San Jacinto-Tizate Geothermal Field, Nicaragua

    SciTech Connect

    Ostapenko, S.; Spektor, S.; Davila, H.; Porras, E.; Perez, M.

    1996-01-24

    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.

  5. Microearthquake Studies at the Salton Sea Geothermal Field

    DOE Data Explorer

    Templeton, Dennise

    2013-10-01

    The objective of this project is to detect and locate microearthquakes to aid in the characterization of reservoir fracture networks. Accurate identification and mapping of the large numbers of microearthquakes induced in EGS is one technique that provides diagnostic information when determining the location, orientation and length of underground crack systems for use in reservoir development and management applications. Conventional earthquake location techniques often are employed to locate microearthquakes. However, these techniques require labor-intensive picking of individual seismic phase onsets across a network of sensors. For this project we adapt the Matched Field Processing (MFP) technique to the elastic propagation problem in geothermal reservoirs to identify more and smaller events than traditional methods alone.

  6. RAPID CASING CORROSION IN HIGH TEMPERATURE LIQUID DOMINATED GEOTHERMAL FIELDS

    SciTech Connect

    Bixley, P.F.; Wilson, D.M.

    1985-01-22

    Downhole logging and workover operations on 12-20 year old wells in several high temperature, liquid-dominated geothermal fields in New Zealand has shown that severe corrosion has commonly occurred in the production casing string where this is unprotected by larger diameter casings. To date corrosion products from only one well have been examined in detail. These indicate that corrosion attack commences at the outer casing wall and continues at a rate as great as 0.8mm/year. Rapid corrosion has been attributed to neutral or slightly acid high bicarbonate waters formed by the absorption of steam and gas into shallow aquifers not directly connected to the deeper, high chloride reservoir.

  7. Geophysical surveys in Parvati valley geothermal field, Kullu, India

    NASA Astrophysics Data System (ADS)

    Rakesh Kumar, S. B.; Singh, Mohan; Gupta, L.; Rao, G. V.

    1982-08-01

    Direct current resistivity surveys and shallow temperature measurements were carried out for geothermal exploration in a part of Parvati valley, goethermal field, Himachal Pradesh, India. At a few places, the Schlumberger soundings pointed to the presence of a relatively low-resistivity shallow layer, which probably represents fractured and jointed quartzite, saturated with hot/cold water. Wenner resistivity profiles indicate the presence of some possible shallow subsurface lateral hot water channels across the valley at Manikaran. Shallow temperature measurements show a good subsurface thermal anomaly near the confluence of the rivers Brahmaganga and Parvati. The results of the survey, together with other available geodata, suggest that an anomalous heat source does not lie beneath the study area. It is postulated that the meteoric water, originating at high elevations after heating as a result of circulation at depth, emerges at the surface in the Parvati valley as hot springs, after mixing in various proportions with near surface cold waters.

  8. Numerical simulation of the Mori geothermal field, JP

    SciTech Connect

    Yukihiro Sakagawa; Masahiro Takahashi; Mineyuki Hanano; Tsuneo Ishido; Nobuhiro Demboya

    1994-01-20

    A numerical study of the Mori geothermal field which consisted of a series of three-dimensional natural state modeling and history matching was carried out with porous models. Finally satisfactory fits both on temperature and pressure of the natural state and on pressure history caused by exploitation were obtained. The results indicate that the deep hot water ascends mainly through the fractures near the caldera wall and the fractures confined to some lithofaces, and some of the ascending hot water flows to the west from the caldera. A sketch of the geological structure, the way of making up the initial numerical model, the way of concluding free parameters, and results of calculations of natural state modeling and history matching for the best numerical model are presented.

  9. Results of investigation at the Ahuachapan Geothermal Field, El Salvador

    SciTech Connect

    Fink, J.B. )

    1990-04-01

    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.

  10. Absence of Remote Triggering in Geothermal Fields Due to Human Activity

    NASA Astrophysics Data System (ADS)

    Ge, S.; Zhang, Q.; Lin, G.

    2014-12-01

    Operational geothermal fields typically have high seismicity rates, which could be caused by both tectonic and anthropogenic activities. Due to the high background seismicity and possible interaction between fluid and seismic waves, geothermal areas have been recognized to be susceptible to large remote earthquakes. However, whether human activity (geothermal production) affects remote earthquake triggering by changing the stress state is unclear. Here we choose two geothermal fields, Coso and Salton Sea in southern California, to study the spatiotemporal distributions of the triggered earthquakes following the 1992 Mw 7.3 Landers and 1999 Mw 7.1 Hector Mine earthquakes. These two geothermal fields have been in operation since 1980s with comparable net capacity, and have long-term geothermal fluid loss. By analyzing the regional catalog recorded by the Southern California Seismic Network, we find that these two operational geothermal areas remain unaffected by the remote mainshocks, whereas the surrounding areas show vigorous triggered responses. We interpret this phenomenon as a result of human activity, which presumably has brought the stress state away from failure by reducing pore pressure. To further understand how much the human activity can affect the stress state, we also conduct a systematic study on Long Valley Caldera in northern California as a comparison site. Long Valley Caldera hosts an active geothermal field with net capacity about one sixth of that in Coso or Salton Sea geothermal field, and the extraction volume is not constantly larger than the injection. We will show comparisons of the triggered response in Long Valley with the two geothermal fields in southern California.

  11. Analysis of the Fractures pattern at the Chingshui geothermal field, Taiwan

    NASA Astrophysics Data System (ADS)

    Lu, C.; Lo, W.; Song, S.

    2010-12-01

    Magma chambers in the shallow crust and shallow intrusive igneous rock result in a high heat flow and geothermal gradient. Hot springs, one of geothermal potential phenomena, is widely distributed in Taiwan, especially in the Slate Belt and Tananao Complex of Central Range. The Slate Belt is mainly composed of meta-sandstone, argillite and slate, which have high porosity for geothermal source reservoirs. While the Tananao Complex is composed of phyllite, schist, gneiss, limestone and amphibolites, which have low porosity, but heat flow can conduct along cleavages, Joints, and other fractures. The purpose of this study is to delineate the fracture pattern and geothermal structure by field geologic survey and joints analysis. The rocks cropping out in the mapped area belong mainly to the Lushan Formation of Miocene age, which can be divided into two members: Chingshuihu member and Jentse member in ascending order. The Chingshuihu member is composed of slate or phyllite with thin beds of metasandstone. The Jentse member is composed of alternation of argillite and metasandstone. The geothermal reservoir of the Chingshui geothermal field might be related to the fault damage zone of the Chingshuihsi fault and Xiaonanao fault. Linking damage zones were caused by the interaction and linkage of fault segments in the geothermal field and developed a wide range of fracture patterns that depend on the nature of the interaction between the two fault segments. The fault damage zone and high porosity of sandstone resulted in well geothermal reservoir. The information obtained from the field geologic survey and Joint analysis indicate that the joint systems could be divided into four sets in terms of the strike and dip. Further, the geothermal reservoir is confined to a zone that extends 800m in width along N30E, 1km in length, and has an 80 dip toward SE. The main geothermal field is found in the NW of the reservoir; this area is located between the Chingshuihsi fault and

  12. Geothermal field case studies that document the usefulness of models in predicting reservoir and well behavior

    SciTech Connect

    Lippmann, M.J.

    1989-03-01

    The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant art of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Falls in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studies we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated with the development and exploitation of geothermal resources. 14 refs., 6 figs.

  13. Geothermal Field Case Studies that Document the Usefulness of Models in Predicting Reservoir and Well Behavior

    SciTech Connect

    Lippmann, Marcelo J.

    1989-03-21

    The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant part of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Fall in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studies we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated with the development and exploitation of geothermal resources.

  14. The Ahuachapan geothermal field, El Salvador: Reservoir analysis

    SciTech Connect

    Aunzo, Z.; Bodvarsson, G.S.; Laky, C.; Lippmann, M.J.; Steingrimsson, B.; Truesdell, A.H.; Witherspoon, P.A.; Icelandic National Energy Authority, Reykjavik; Geological Survey, Menlo Park, CA; Lawrence Berkeley Lab., CA )

    1989-08-01

    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.

  15. Velocity and Attenuation Structure of the Geysers Geothermal Field, California

    SciTech Connect

    Zucca, J. J.; Hutchings, L. J.; Kasameyer, P. W.

    1993-01-01

    The Geysers geothermal field is located in northern California and is one of the world's largest producers of electricity from geothermal energy. The resource consists of primarily dry steam which is produced from a low, porosity fractured graywacke. Over the last several years steam pressure at the Geysers has been dropping. Concern over decline of the resource has prompted research to understand its fundamental nature. A key issue is the distribution of fluid in the matrix of the reservoir rock. In this paper we interpret seismic compressional-wave velocity and attenuation data at the Geysers in terms of the geologic structure and fluid saturation in the reservoir. Our data consist of approximately 300 earthquakes that are of magnitude 1.2 and are distributed in depth between sea level and 2.5 km. Using compressional-wave arrival times, we invert for earthquake location, origin time, and velocity along a three-dimensional grid. Using the initial pulse width of the compressional-wave, we invert for the initial pulse width associated with the source, and the one-dimensional Q structure. We find that the velocity structure correlates with known mapped geologic units, including a velocity high that is correlated with a felsite body at depth that is known from drilling. The dry steam reservoir, which is also known from drilling, is mostly correlated with low velocity. The Q increases with depth to the top of the dry steam reservoir and decreases with depth within the reservoir. The decrease of Q with depth probably indicates that the saturation of the matrix of the reservoir rock increases with depth.

  16. Full Moment Tensor Analysis at The Geysers Geothermal Field

    NASA Astrophysics Data System (ADS)

    Boyd, O. S.; Dreger, D. S.; Hellweg, M.; Lombard, P. N.; Ford, S. R.; Taira, T.; Taggart, J.; Weldon, T. J.

    2011-12-01

    Geothermal energy has been produced at The Geysers Geothermal Field in Northern California for more than forty years. It has been demonstrated that increased steam production and fluid injection correlates positively with changes in earthquake activity, resulting in thousands of tiny earthquakes each year with events ranging in magnitude up to 4.5. We determine source parameters for the largest of these earthquakes using a regional distance moment tensor method. We invert three-component, complete waveform data from broadband stations of the Berkeley Digital Seismic Network, the Northern California Seismic Network and the USArray deployment (2005-2007) for the complete, six-element moment tensor. Some solutions depart substantially from a pure double-couple with some events having large volumetric components. Care is needed in the assessment of the significance of the non-double-couple terms. We have worked to develop a systematic procedure for the evaluation of aleatoric and epistemic solution uncertainty (e.g. Ford et al., 2009; Ford et al., 2010). We will present the solutions for The Geysers events together with estimates of random errors and systematic errors due to imperfect station coverage and knowledge of the velocity structure, which are needed to compute Green's functions for the inversion. Preliminary results indicate that some events have large isotropic components that appear to be stable and suggestive of fluid or gas involvement during the rupture processes. We are presently incorporating full moment tensor capability in the Berkeley Seismological Laboratory's automatic processing system and analyst interface. This upgrade will enable improved monitoring at The Geysers and volcanically active regions of California.

  17. Microearthquakes in the ahuachapan geothermal field, el salvador, central america.

    PubMed

    Ward, P L; Jacob, K H

    1971-07-23

    Microearthquakes occur on a steeply dipping plane interpreted here as the fault that allows hot water to circulate to the surface in the geothermal region. These small earthquakes are common in many geothermal areas and may occur because of the physical or chemical effects of fluids and fluid pressure.

  18. Gas chemistry and thermometry of the Cerro Prieto geothermal field

    SciTech Connect

    Nehring, N.L.; D'Amore, F.

    1981-01-01

    Geothermal gases at Cerro Prieto are derived from high temperature reactions within the reservoir or are introduced with recharge water. Gases collected from geothermal wells should, therefore, reflect reservoir conditions. Interpretation of gas compositions of wells indicates reservoir temperatures, controls of oxygen and sulfur fugacities, and recharge source and direction.

  19. Seismostatistical characterization of microseismicity observed at geothermal fields

    NASA Astrophysics Data System (ADS)

    Eto, T.; Asanuma, H.; Adachi, M.; Saeki, K.; Aoyama, K.; Ozeki, H.; Häring, M. O.

    2012-12-01

    Recently, occurrence of felt earthquakes has been recognized as one of the most critical environmental burdens associated with geothermal development. We have taken seismostatistical approach to evaluate characteristics of the microseismicity at geothermal fields to establish realtime and automated monitoring techniques of the reservoir changes and risk assessment of the felt earthquakes. In this study, we have introduced the Epidemic Type Aftershock Sequence (ETAS) model (Ogata, JASA, 1988) to statistically model the time series of occurrences and the magnitude of microseismic events from hydrothermal and EGS fields. Here maximum likelihood estimation has been employed to estimate optimum parameters of the ETAS model. We analyzed microseismic events observed at Yanaizu Nishiyama, one of the largest hydrothermal fields in Japan. In this field, four felt earthquakes with local magnitude larger than 3.0 occurred during production operation since 1996, although no clear correlation between the occurrence of the felt earthquakes and operation to the reservoir has been observed (Asanuma et al., Trans. GRC, 2011). We found that the occurrence rate of primary fluid signals, which are the events triggered by external forcing and have been interpreted to be independent from a series of aftershocks (Hainzl and Ogata, JGR, 2005), correlated to the reinjection rate (Fig. 1). However, no significant change in the other parameters in the ETAS model has been observed. We also analyzed microseismic events observed at Basel EGS site in Switzerland, where some felt earthquakes occurred during and after hydraulic stimulation. The estimated ETAS model demonstrated that there is a correlation between the occurrence rate of primary fluid signals and injection rate. We, however, found that there is limitation to fit the ETAS model to the induced seismic events and new seismostatistical model is required for microseismic reservoir monitoring.ig. 1 A relation among production

  20. Natural State Model of the Nesjavellir Geothermal Field, Iceland

    SciTech Connect

    Bodvarsson, G.S.; Pruess, K.; Stefansson, V.; Steingrimsson, B.; Bjornsson, S.; Gunnarsson, A.; Gunnlaugsson, E.

    1986-01-21

    The Nesjavellir geothermal system in southern Iceland is very complex from both a thermal and hydrologic point of view. There are large pressure and temperature gradients in the wellfield and zones with drastically different pressure potentials. Thus, natural fluid flow is substantial in the system and flow patterns are complex. We have developed a two-dimensional natural state model for the Nesjavellir system that matches reasonably well the observed pressure and temperature distributions. The match with field data has allowed determination of the energy recharge to the system and the permeability distribution. Fluids recharge the system at rate of 0.02 kg/s/m with an enthalpy of 1460 kJ/kg. The permeability in the main reservoir is estimated to be in the range of 1.5 to 2.0 md, which agrees well with injection test results from individual wells. Permeabilities in shallower reservoirs are about an order of magnitude higher. Most of the main reservoir is under twephase conditions, as are shallow aquifers in the southern part of the field. The model results also suggest that the low temperatures in the shallow part of the northern region of the field may be due to the young age of the system; i.e., the system is gradually heating up. If this is the case the estimated age of the system near the wellfield is on the order of a few thousand years.

  1. Reservoir analysis of the Palinpinon geothermal field, Negros Oriental, Philippines

    SciTech Connect

    Amistoso, A.E.; Aquino, B.G.; Aunzo, Z.P.; Jordan, O.T.; Ana, F.X.M.S.; Bodvarsson, G.S.; Doughty, C.

    1993-10-01

    The Philippine National Oil Company and Lawrence Berkeley Laboratory have conducted an informal cooperative project on the reservoir evaluation of the Palinpinon geothermal field in the Philippines. The work involved the development of various numerical models of the field in order to understand the observed data. A three-dimensional porous medium model of the reservoir has been developed that matches well the observed pressure declines and enthalpy transients of the wells. Submodels representing the reservoir as a fractured porous medium were developed for the analysis of chemical transport of chlorides within the reservoir and the movement of the cold water front away from injection wells. These models indicate that the effective porosity of the reservoir varies between 1 and 7% and the effective permeability between 1 and 45 millidarcies. The numerical models were used to predict the future performance of the Palinpinon reservoir using various possible exploitation scenarios. A limited number of make-up wells were allocated to each sector of the field. When all the make-up wells had been put on line, power production gradually began to decline. The model indicates that under the assumed conditions it will not be possible to maintain the planned power production of 112.5 MWe at Palinpinon I and 80 MWe at Palinpinon II for the next 30 years, but the decline in power output will be within acceptable normal operating capacities of the plants.

  2. 3D Magnetotelluic characterization of the Coso GeothermalField

    SciTech Connect

    Newman, Gregory A.; Hoversten, G. Michael; Wannamaker, Philip E.; Gasperikova, Erika

    2007-04-23

    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

  3. Tentative estimate of bulk permeability of basement rocks from heat discharges in a geothermal field

    NASA Astrophysics Data System (ADS)

    Sekioka, Mitsuru

    1988-09-01

    A simple, columnar model is applied to fissured basement rocks including a geothermal reservoir at depth in a geothermal system to derive a formula determining the bulk permeability of the rocks (the extended permeability averaged for the whole fissured basement rocks), under some assumptions and approximations. The bulk permeability is found to depend mainly upon the conductive and convective heat discharges and the thermal conductivity of the rock in steaming grounds. Tentative estimate of the bulk permeability is carried out for the eight geothermal fields in Japan where the above three variables are available. Finally, the field data are presented to support a part of the estimated bulk permeability.

  4. Discovery and geology of the Desert Peak geothermal field: a case history. Bulletin 97

    SciTech Connect

    Benoit, W.R.; Hiner, J.E.; Forest, R.T.

    1982-09-01

    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.

  5. Generating capacity of the Heber geothermal field, California

    SciTech Connect

    Lippmann, M.J.; Bodvarsson, G.S.

    1983-12-01

    Using numerical simulation techniques and the radial model developed for the study of the natural state of the Heber field (Lippmann and Bodvarsson, 1983b), the response of this geothermal system to exploitation is analyzed. In this study the generation rate in the field is allowed to build up over a period of 10 years; after that, 30 years of constant power production is assumed. Full (100%) injection of the spent brines is considered, the fluids being injected 2250 m (near injection) or 4250 m (far injection) from the center of the system. The study shows that a maximum of 6000 kg/s (equivalent to approximately 300 MW/sub e/) of fluids may be produced for the near injection case, but only 3000 kg/s (equivalent to approximately 150 MW/sub e/) for the far injection case. The results indicate that the possible extraction rates (generating capacity) generally are limited by the pressure drop in the reservoir. The average temperature of the produced fluids will decline 10 to 18/sup 0/C over the 40-year period.

  6. Seismotectonics of the Cerro Prieto Geothermal Field, Baja California, Mexico.

    NASA Astrophysics Data System (ADS)

    Rebollar, C. J.; Reyes, L. M.; Quintanar, L.; Arellano, J. F.

    2002-12-01

    We studied the background seismic activity in the Cerro Prieto geothermal field (CPGF) using a network of 21 digital stations. Earthquakes are located below the exploitation area of the CPGF, between 3 and 12 km depth, within the basement. Earthquakes follow roughly a N30°E trend perpendicular to the Cerro Prieto fault. This activity is located on a horst-like structure below the geothermal field and coincides with the zone of maximum subsidence in the CPGF. Two earthquake swarms occurred along the SE-NW strike of the Cerro Prieto fault and in the neighborhood of the Cerro Prieto volcano. Magnitudes range from -0.3 to 2.5. A Vp/Vs=1.91 ratio of the activity below the volcano suggests a water-saturated medium and/or a partial-melt medium. We calculated 76 focal mechanisms of individual events. On June 1 and September 10, 1999, two earthquakes of Mw 5.2 and 5.3 occurred in the basement at depths of 7.4 and 3.8 km below the CPGF. Maximum peak accelerations above the hypocenter ranged from 128.0 to 432.0 cm/s2. Waveform modeling results in a fault geometries given by strike=236°, dip=60°, rake=-58° (normal) and strike=10°, dip=90°, rake=159° (right lateral strike-slip) for the June and September events. Observed triangular source time function of 0.7 seconds and a double source with a total duration of 1.9 seconds for the June and September events were used to calculate the synthetics seismograms. Static stress drops and seismic moments for the June and September events are: Δ\\sigma=82.5 MPa (825 bars), Mo= 7.65x1016 Nm (7.65x1023 dyne-cm) and Δ\\sigma=31.3 MPa (313 bars) and Mo=1.27x1017 Nm (1.27x1024 dyne-cm). These stress drops are typical of continental events rather than stress drops of events originated in spreading centers. We concluded from the focal mechanisms of the background seismicity and June and September 1999 events, that a complex stress environment exits in the CPGF due to the continual thinning of the crust in the Cerro Prieto basin.

  7. Multidisciplinary exploration of the Tendaho Graben geothermal fields

    NASA Astrophysics Data System (ADS)

    Armadillo, Egidio; Rizzello, Daniele; Verdoya, Massimo; Pasqua, Claudio; Marini, Luigi; Meqbel, Naser; Stimac, Jim; Kebede, Solomon; Mengiste, Andarge; Hailegiorgis, Getenesch; Abera, Fitsum; Mengesha, Kebede

    2017-04-01

    The NW-SE trending Tendaho Graben is the major extensional feature of the Afar, Ethiopia. Rifting and volcanic activity within the graben occurred mostly between 1.8 and 0.6 Ma, but extended to at least 0.2 Ma. Very recent (0.22- 0.03 Ma) activity is focused along the southern part of the younger and active Manda Hararo Rift, which is included in the north-western part of the graben. Extension gave rise to about 1600 m of vertical displacement (verified by drilling) of the basaltic Afar Stratoid sequence, over a crust with a mean thickness of about 23 km. The infill of graben, overlying the Stratoids, consists of volcanic and sedimentary deposits that have been drilled by six exploratory wells. Within the graben, two main geothermal fields have been explored by intensive geological, geochemical and geophysical surveys over an area that approximately covers a square sector of 40x40 km. Both new and existing data sets have been integrated. The Dubti-Ayrobera system is located along the central axis of the graben. Available data, acquired in the last three decades, comprise more than two thousands gravity and magnetic stations, 229 magnetotelluric stations and structural-geological and geochemical observations. The Alalobeda system is located along the SW flank of the graben, at about 25 km from the Dubti-Ayrobera system and has been very recently studied by means of gravimetric (300 stations), magnetotelluric and TDEM (140 stations) geological and geochemical surveys. The new residual magnetic anomaly map has been used to map the younger normal polarity basalt distribution and infer the location of the unknown main rift axis. The bedrock surface resulting by the 3D inversion of the new residual Bouguer anomaly enlightens the main normal faults hindered by sediments and the secondary structures represented by horsts and grabens. The three-dimensional resistivity models allow mapping the sedimentary infill of the graben, fracture zones in the Afar Stradoids bedrock and

  8. Analysis of pressure transient data from the Sumikawa geothermal field

    SciTech Connect

    Ishido, T.; Kikuchi, T.; yano, Y.; Miyazaki, Y.; Nakao, S.; Hatakeyama, K.

    1992-01-01

    The permeability structure of the Sumikawa geothermal field in northern Japan has been the subject of an extensive pressure-transient testing investigation since 1986. In this paper, various pertinent data sets are presented and analyzed, including results showing reservoir heterogeneity (i.e. boundary) effects and apparent double porosity behavior. Interference tests between wells SB-3 and SD-2 (both of which have feedpoints in dacitic layers in the ''marine-volcanic complex'' formation) were carried out during 1990. The results have been interpreted to indicate the presence of a moderately high permeability ({approx} 4 darcy-meters) layer with two impermeable boundaries intersecting at a right angle. The 1988 pressure buildup data for well SN-7D are also explained by assuming two impermeable boundaries in a high transmissivity reservoir within the deep ''granodiorite'' formation. Interference tests between wells S-4 and KY-1 have suggested that a very permeable north-south channel is present in the ''altered andesite'' layer. Although the response was successfully interpreted using an ''anisotropic line-source model'' by Garg et al. (1991), a ''double porosity channel model'' seems to be particularly applicable for explaining both the short-term and long-term behavior observed in this series of tests.

  9. Results of investigations at the Ahuachapan geothermal field, El Salvador

    SciTech Connect

    Dennis, B.; Goff, F.; Van Eeckhout, E.; Hanold, B.

    1990-04-01

    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.

  10. Radon and ammonia transects across the Cerro Prieto geothermal field

    SciTech Connect

    Semprini, L.; Kruger, P.

    1981-01-01

    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.

  11. Thermal Fracturing of Volcanic Rocks for Geothermal Field Applications

    NASA Astrophysics Data System (ADS)

    Imaro, Tulus; Deon, Fiorenza; Bakker, Richard; Barnhoorn, Auke

    2017-04-01

    Thermal fracturing is considered to be a potential mechanism to create additional fractures in geothermal fields. The injected cold water into the hot host rock suddenly cools down the host rock, causing a considerable shrinkage of the material and thus potentially increased local stresses that may potentially lead to the formation of cooling related fractures. This is likely to happen in the near wellbore environment or along existing faults or fractures, ie. areas where the hot rocks juxtaposed to cold fluids. In this research, we experiment with thermal fracturing by exposing heated granitic and basaltic samples with cold water to see the extend of the thermal microfracturing inside the samples at different temperatures. Before and after the heat treatment, the micro CT-scanner is used to get high-resolution 3D images of fracture planes and fracture network connectivity. Moreover, the porosity is measured before and after treatment by using the pycnometer to see the effect of the different temperatures. In addition, the changes in geomechanical behaviour are tested by using an unconfined compressive strength (UCS) apparatus on heat treated and non-heat treated samples. We compare the changes in Young Modulus, Poisson's Ratio and ultimate strength of the various samples and record the influence of the thermal fractures on the stress-driven fracturing behaviour in the UCS test.

  12. Field Studies of Geothermal Reservoirs Rio Grande Rift, New Mexico

    SciTech Connect

    James C Witcher

    2002-07-30

    The Rio Grande rift provides an excellent field laboratory to study the nature of geothermal systems in an extensional environment. Much of the geologic complexity that is found in the Basin and Range is absent because the rift is located on cratonic crust with a thin and well-characterized Phanerozoic stratigraphy and tectonic history. On the other hand, the Neogene thermo-tectonic history of the rift has many parallels with the Basin and Range to the west. The geology of the southern Rio Grande rift is among the best characterized of any rift system in the world. Also, most geologic maps for the region are rather unique in that detailed analyses of Quaternary stratigraphic and surficial unit are added in concert with the details of bedrock geology. Pleistocene to Holocene entrenchment of the Rio Grande and tributaries unroofs the alteration signatures and permeability attributes of paleo outflow plumes and upflow zones, associated with present-day, but hidden or ''blind,'' hydrothermal systems at Rincon and San Diego Mountain.

  13. Fluid flow model of the Cerro Prieto Geothermal Field based on well log interpretation

    SciTech Connect

    Halfman, S.E.; Lippmann, M.J.; Zelwe, R.; Howard, J.H.

    1982-08-10

    The subsurface geology of the Cerro Prieto geothermal field was analyzed using geophysical and lithologic logs. The distribution of permeable and relatively impermeable units and the location of faults are shown in a geologic model of the system. By incorporating well completion data and downhole temperature profiles into the geologic model, it was possible to determine the direction of geothermal fluid flow and the role of subsurface geologic features that control this movement.

  14. Fluid flow model of the Cerro Prieto geothermal field based on well log interpretation

    SciTech Connect

    Halfman, S.E.; Lippmann, M.J.; Zelwer, R.; Howard, J.H.

    1982-10-01

    The subsurface geology of the Cerro Prieto geothermal field was analyzed using geophysical and lithologic logs. The distribution of permeable and relatively impermeable units and the location of faults are shown in a geologic model of the system. By incorporating well completion data and downhole temperature profiles into the geologic model, it was possible to determine he direction of geothermal fluid flow and the role of subsurface geologic features that control this movement.

  15. Energy Optimization Modeling of Geothermal Power Plant (Case Study: Darajat Geothermal Field Unit III)

    NASA Astrophysics Data System (ADS)

    Sinaga, R. H. M.; Darmanto, P. S.

    2016-09-01

    Darajat unit III geothermal power plant is developed by PT. Chevron Geothermal Indonesia (CGI). The plant capacity is 121 MW and load 110%. The greatest utilization power is consumed by Hot Well Pump (HWP) and Cooling Tower Fan (CTF). Reducing the utility power can be attempted by utilizing the wet bulb temperature fluctuation. In this study, a modelling process is developed by using Engineering Equation Solver (EES) software version 9.430.The possibility of energy saving is indicated by Specific Steam Consumption (SSC) net in relation to wet bulb temperature fluctuation from 9°C up to 20.5°C. Result shows that the existing daily operation reaches its optimum condition. The installation of Variable Frequency Drive (VFD) could be applied to optimize both utility power of HWP and CTF. The highest gain is obtained by VFD HWP installation as much as 0.80% when wet bulb temperature 18.5 °C.

  16. Spatial Correlation of Airborne Magnetic Anomalies with Reservoir Temperatures of Geothermal Fields, Western Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Ertekin, Can; Ekinci, Yunus Levent

    2013-04-01

    Geothermal areas in Western Anatolia are remarkably located throughout Büyük Menderes Graben (BMG) and Gediz Graben (GG). These E-W trending grabens have been subjected to N-E stretching since Miocene. Except for these major outcomes of the extensional forces, NE-SW oriented and relatively short grabens take place in Western Anatolia as well. Among them, BMG and GG are remarkable with topographic escarpments that reveal footwall of steeply-dipping active normal faults. They manifest themselves via numerous earthquakes and geothermal activity (fluid discharges from springs and wells). Geothermal discharges are aligned along the rims of E-W trending normal faults trending over detachment faults. Concerning BMG, geothermal manifestations extend along the northern sector of the graben. Geothermal reservoirs inside BMG are the limestone and conglomerate units within Neogene sediments and the marble-quartzite units within The Menderes Massif rocks. The main high and low enthalpy geothermal fields along BMG and their reservoir temperatures are as follows: Kızıldere (242°C), Germencik (232°C), Aydın-Ilıcabası (101°C), Yılmazköy (142°C), Salavatlı (171°C), Söke (26°C), Pamukkale (36°C), Karahayıt (59°C), Gölemezli (101°C) and Yenice (70°C). Through GG, reservoir temperatures decrease from east to west. Geothermal reservoirs inside GG are metamorphics and granodiorite of the Menderes Massif rocks. The Neogene sediments act as cap rock of the geothermal reservoirs. Geothermal fields inside the graben and their reservoir temperatures are as follows: Alaşehir (215°C), Salihli (155°C), Urganlı (85°C), Kurşunlu (135°C), Caferbey (150°C), Sart (100°C). In order to investigate the spatial correlation of magnetic anomalies and the reservoir temperatures of geothermal fields in the region, we analysed airborne magnetic data which were collected by General Directorate of Mineral Research and Exploration (MTA) of Turkey. Airborne magnetic data were taken

  17. Magmatic Fluid Source of the Chingshui Geothermal Field: Evidence of Carbonate Isotope data

    NASA Astrophysics Data System (ADS)

    Song, S. R.; Lu, Y. C.; Wang, P. L.; John, C. M.; MacDonald, J.

    2015-12-01

    The Chingshui geothermal field is located at the northern tip of the Miocene Lushan Slate Formation, which was part of the Eurasian continental margin subject to the Plio-Pleistocene collision associated with the Luzon Arc. The remnant heat of the Taiwan orogeny has long been considered to drive the circulation of hydrothermal fluids in the Chingshui geothermal field. However, recent studies based on magnetic anomalies and helium isotopic ratios suggest that the heat might instead be derived from igneous bodies. By examining isotope data of calcite veins and scaling in geothermal wells, this study aimed to clarify the fluid origin and possible heat source accounting for the geothermal fluids in the Chingshui geothermal field. Carbon and oxygen isotope analyses indicate that veins from outcrops and scalings in geothermal wells have high and low d values, respectively. Data for veins in drilled cores fall in between outcrop veins and scalings values. Such an isotopic pattern could be interpreted as the mixing of two end member fluids. The clumped isotope analysis of calcite veins from the outcrops yielded precipitation temperatures of up to 232 ± 16 ℃ and a reconstructed d18O fluid value of 9.5 ‰(magmatic fluid: 6-11 ‰; metamorphic fluid: 5-28 ‰ by Taylor, 1974). The inferred d18O values of hot fluids for the vein formation are significantly different from that of meteoric water in Chingshui area (around -5.4 ‰) as well as the scaling in geothermal wells (around -7.6 ‰). Previous study of magnetotelluric image demonstrated two possible fluid reservoirs at different depths (Chen et al. 2012). Our isotope data combined with these lines of evidence suggest that the scaling in geothermal wells could be derived from fluids originating from the shallower reservoir. In contrast, the veins present at outcrops could have been formed from 18O-enriched, deeply-sourced fluids related to either metamorphic dehydration or magmatic processes.

  18. Miravalles Geothermal Project: Portable Well Flow Test Equipment and Procedures Manual

    SciTech Connect

    1980-05-01

    The well flow test program has been designed to facilitate the gathering of information, with portable test equipment, from various wells with regard to their capability of flow, the quality of steam produced at various back pressures, the composition and quantity of noncondensable gases flashed from the wells and the composition and quantity of solids in the well's liquid streams (brine). The test program includes procedures for obtaining the following basic flow data pertinent to the plant power cycle design: (1) Effluent steam and brine flows, pressures and temperatures; (2) Noncondensable and dissolved gas contents in steam and brine; (3) H{sub s}S content in gases formed; and (4) Solids content and chemical analysis of steam and brine.

  19. Mushroom growing project at the Los Humeros, Mexico geothermal field

    SciTech Connect

    Rangel, M.E.R.

    1998-12-01

    There are several projects of direct (non-electrical) use of geothermal energy in Mexico. Personnel of the Comision Federal de Electricidad (CFE) have experience in various of these projects, like drying of timber and fruits, space heating, food processing, etc. Taking this in consideration, CFE built the Los Humeros mushroom plant using for heat source the geothermal steam from Well H-1. The main purpose of the project was to take advantage of residual geothermal energy in a food production operation and to develop the appropriate technology. In 1992, existing installations were renovated, preparing appropriate areas for pasteurization, inoculation and production. The mushroom Pleurotus ostreatus var. florida and columbinus was used. A year later, CFE proposed the construction of improved facilities for growing edible mushrooms. New materials and equipment, as well as different operation conditions, were proposed on the basis of the experience gained in the initial project. The construction and renovation activities were completed in 1994.

  20. Structural compartmentalisation of a geothermal system, the Torre Alfina field (central Italy)

    NASA Astrophysics Data System (ADS)

    Vignaroli, Gianluca; Pinton, Annamaria; De Benedetti, Arnaldo A.; Giordano, Guido; Rossetti, Federico; Soligo, Michele; Berardi, Gabriele

    2013-11-01

    Recent surging of renewed industrial interest in the exploration of low and medium enthalpy geothermal fields makes the accurate assessment of the geothermal potential essential to minimise uncertainties during both exploration and exploitation. The Torre Alfina field is a case of abandoned, but promising, geothermal field of central Italy where the roles of the internal structural setting and of the recharge areas on the hydrothermal circulation are largely unconstrained. In this paper, field structural data integrated with geomorphic lineament analysis document the occurrence of post-orogenic deformation structures controlling the compartmentalisation of the Torre Alfina geothermal field. Strike-slip and subordinate normal fault systems (with associated network fractures) cut and dislocate the internal architecture of the reservoir and prevent its hydraulic connection with Mount Cetona, considered to be the recharge area and where hydrothermal manifestation, including travertine deposition, occurs. 230Th/234U radiometric dating of superposed travertine units gives 200, 120 and 90 ka respectively, inferred to correspond to the age of the fossil hydrothermal circulation during tectonic activity. The results have been used for illustrating a new geological conceptual model for the Torre Alfina area where the geothermal system is composed of different compartments. Tectonic structures define the main boundaries between compartments, helping the understanding of why productive and non-productive wells were found in apparently similar structural settings within the Torre Alfina field.

  1. Preliminary investigation of scale formation and fluid chemistry at the Dixie Valley Geothermal Field, Nevada

    SciTech Connect

    Bruton, C.J.; Counce, D.; Bergfeld, D.; Goff, F.; Johnson, S.D.; Moore, J.N.; Nimz, G.

    1997-06-27

    The chemistry of geothermal, production, and injection fluids at the Dixie Valley Geothermal Field, Nevada, was characterized to address an ongoing scaling problem and to evaluate the effects of reinjection into the reservoir. Fluids generally followed mixing-dilution trends. Recharge to the Dixie Valley system apparently originates from local sources. The low-pressure brine and injection waters were saturated with respect to amorphous silica, which correlated with the ongoing scaling problem. Local shallow ground water contains about 15% geothermal brine mixed with regional recharge. The elevated Ca, Mg, and HCO{sub 3} content of this water suggests that carbonate precipitation may occur if shallow groundwater is reinjected. Downhole reservoir fluids are close to equilibrium with the latest vein mineral assemblage of wairakite-epidote-quartz-calcite. Reinjection of spent geothermal brine is predicted to affect the region near the wellbore differently than it does the region farther away.

  2. Geothermal well-field and power-plant investment-decision analysis

    SciTech Connect

    Cassel, T.A.V.; Amundsen, C.B.; Edelstein, R.H.; Blair, P.D.

    1981-05-31

    Investment decisions pertaining to hydrothermal well fields and electric power plants are analyzed. Geothermal investment decision models were developed which, when coupled to a site-specific stochastic cash flow model, estimate the conditional probability of a positive decision to invest in the development of geothermal resource areas. Quantitative decision models have been developed for each major category of investor currently involved in the hydrothermal projects. These categories include: large, diversified energy resource corporations; independently operating resource firms; investor-owned electric utilities; municipal electric utilities; state-run resource agencies; and private third-party power plant investors. The geothermal cash flow, the investment decision analysis, and an example of model application for assessing the likely development of geothermal resource areas are described. The sensitivity of this investment behavior to federal incentives and research goals is also analyzed and discussed.

  3. The Momotombo Geothermal Field, Nicaragua: Exploration and development case history study

    SciTech Connect

    1982-07-01

    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

  4. Simple interpretations of chemical transients in multi-feed, two-phase geothermal wells; Examples from Philippine Geothermal fields

    SciTech Connect

    Ruaya, J.R.; Solis, R.P.; Solana, R.R.; Seastres, J.S. Jr. )

    1991-01-01

    This paper reports that the main process responsible for the extreme variations in chloride concentrations in the water discharged by selected multi-feed, two-phase geothermal wells in the Philippines is steam addition brought about by fluid flashing in the formation or by a shallow and distinct steam zone. Correlation of enthalpy with chloride data over a span of seven years for well 106, Tongonan field, revealed the entry of reservoir fluid from the hotter portion of the field as the well responded to exploitation. Using a plot of discharge enthalpy versus total chloride, the deep chloride near well OP-3D which is drilled at the periphery of the Bacon-Manito field, has been determined at about 8700 mg/k. This is somewhat higher than the inferred chloride level of 7000 mg/kg in the postulated main geothermal reservoir. The competing effects of returns of reinjected water and flashing in the formation on the observed chloride concentrations in the discharge water of well PN-20D, Palinpinon field, have been segregated using the technique described above.

  5. Reservoir engineering applications for development and exploitation of geothermal fields in the Philippines

    SciTech Connect

    Vasquez, N.C.; Sarmiento, Z.F.

    1986-07-01

    After a geothermal well is completed, several tests and downhole measurements are conducted to help evaluate the subsurface fluid and reservoir properties intersected. From these tests, a conceptual model of the well can be developed by integrating data from the various parts of the field. This paper presents the completion techniques applied in geothermal wells, as well as the role of reservoir engineering science in delineating a field for development. Monitoring techniques and other reservoir engineering aspects of a field under exploitation are also discussed, with examples from the Philippines.

  6. Geothermal Systems of the Yellowstone Caldera Field Trip Guide

    SciTech Connect

    Foley, Duncan; Neilson, Dennis L.; Nichols, Clayton R.

    1980-09-08

    Geothermal studies are proceedings on two fronts in the West Yellowstone area. High-temperature resources for the generation of electricity are being sought in the Island Park area, and lower temperatures resources for direct applications, primarily space heating, are being explored for near the town of West Yellowstone. Potential electric geothermal development in the Island Park area has been the subject of widespread publicity over fears of damage to thermal features in Yellowstone Park. At the time of writing this guide, companies have applied for geothermal leases in the Island Park area, but these leases have not yet been granted by the US Forest Service. The Senate is now discussing a bill that would regulate geothermal development in Island Park; outcome of this debate will determine the course of action on the lease applications. The Island Park area was the site of two cycles of caldera activity, with major eruptions at 2.0 and 1.2 million years ago. The US Geological Survey estimates that 16,850 x 10{sup 18} joules of energy may remain in the system. Geothermal resources suitable for direct applications are being sought in the West Yellowstone vicinity by the Montana Bureau of Mines and Geology, under funding from the US Department of Energy. West Yellowstone has a mean annual temperature of 1-2 C. Research thus far suggests that basement rocks in the vicinity are at a depth of about 600 m and are probably similar to the rocks exposed north of Hebgen Lake, where Precambrian, Paleozoic and Mesozoic rocks have been mapped. A few sites with anomalously warm water have been identified near the town. Work is continuing on this project.

  7. Sustainability assessment of geothermal exploitation by numerical modelling: the example of high temperature Mofete geothermal field at Campi Flegrei caldera (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Carlino, Stefano; Troiano, Antonio; Giulia Di Giuseppe, Maria; Tramelli, Anna; Troise, Claudia; Somma, Renato; De Natale, Giuseppe

    2015-04-01

    The active volcanic area of Campi Flegrei caldera has been the site of many geothermal investigations, since the early XX century. This caldera is characterised by high heat flow, with maximum value > 150 mWm-2, geothermal gradients larger than 200°Ckm-1 and diffuse magmatic gases discharge at the surface. These features encouraged an extensive campaign for geothermal investigation, started in 1939, with many drillings performed at Campanian volcanoes (Campi Flegrei and Ischia) and later at Vesuvius. Several wells aimed to the exploitation of high enthalpy geothermal energy, were drilled in the Campi Flegrei caldera, down to a maximum depth of ~3 km involving mainly two sites (Mofete and S.Vito geothermal fields) located in western and northern sector of caldera respectively. The most interesting site for geothermal exploitation was the Mofete zone, where a number of 4 productive wells were drilled and tested to produce electrical power. Based on data inferred from the productive tests it was established a potential electrical extractable power from Mofete field of at least 10MWe. More recently an empirical evaluation of the whole geothermal potential of the caldera provides a value of more than 1 GWe. The results of AGIP-ENEL exploration at Campi Flegrei highlighted the feasibility of geothermal exploitation. Here, we show for the first time the results of numerical simulations (TOUGH2 code ®) of fluids extraction and reinjection from the Mofete geothermal field, in order to produce at least 5MWe from zero emission power plant (Organic Rankine Cycle type). The simulation is aimed to understand the perturbation of the geothermal reservoir in terms of temperature, pressure change, and possible related seismicity, after different simulated time of exploitation. The modeling is mainly constrained by the data derived from geothermal exploration and productive tests performed since 1979 by AGIP-ENEL Companies. A general assessment of the maximum potential magnitude

  8. Numerical simulations of passing seismic waves at the Larderello-Travale Geothermal Field, Italy

    NASA Astrophysics Data System (ADS)

    Lupi, Matteo; Fuchs, Florian; Saenger, Erik H.

    2017-06-01

    Passing seismic waves released by large-magnitude earthquakes may affect geological systems located thousands of miles far from the epicenter. The M9.0 Tohoku earthquake struck on 11 March 2011 in Japan. We detected local seismic activity at the Larderello-Travale geothermal field, Italy, coinciding with the maximum amplitudes of the Rayleigh waves generated by the Tohoku earthquake. We suggest that the earthquakes were triggered by passing Rayleigh waves that induced locally a maximum vertical displacement of approximately 7.5 mm (for waves with period of 100 s). The estimated dynamic stress was about 8 kPa for a measured peak ground velocity of 0.8 mm/s. Previous similar observations pointed out local seismicity at the Larderello-Travale Geothermal Field triggered by the 2012 Mw5.9 Po Plain earthquake. We conducted forward numerical modeling to investigate the effects caused by passing P, S, Love, and Rayleigh waves through the known velocity structure of the geothermal field. Results indicate that maximum displacements focus differently when considering body or surface waves, with displacement values being higher within the first 2 km of depth. The focusing of the displacement below 3 km seems to be strongly controlled by the velocity structure of the Larderello-Travale geothermal field. We propose that seismic activity triggered by passing seismic waves may be related to a clock-advancing mechanism for local seismic events that may have occurred in any case. Furthermore, our analysis shows that local anisotropies in the velocity structure of the Larderello-Travale geothermal field (possibly linked to compartments of elevated pore pressures) strongly control the reactivation of regions of the geothermal field affected by passing seismic waves.

  9. The Krafla Geothermal Field, Iceland: 3. The Generating Capacity of the Field

    NASA Astrophysics Data System (ADS)

    Bodvarsson, G. S.; Pruess, K.; Stefansson, V.; Eliasson, E. T.

    1984-11-01

    This paper presents analytical and numerical studies of the generating capacity of the Krafla field. A general lumped parameter model is developed which can be used to obtain rough estimates of the generating capacity of a geothermal field based on the size of the wellfield, the average formation porosity, and the amount of recharge to the system. The model is applied to the old wellfield at Krafla. More sophisticated calculations of the generating capacity of the Krafla field are also performed using distributed-parameter models. Two-dimensional areal models of the various reservoir regions at Krafla are developed and their generating capacities (MWe) evaluated. The results obtained indicate that the old wellfield can sustain steam production of 30 MWe for 30 years. The estimated power potential of the new wellfield is 20 MWe for 30 years. To obtain the required steam production several additional wells may be drilled in the old and new wellfields.

  10. Analysis of Injection-Induced Micro-Earthquakes in a Geothermal Steam Reservoir, The Geysers Geothermal Field, California

    SciTech Connect

    Rutqvist, Jonny; Rutqvist, J.; Oldenburg, C.M.

    2008-05-15

    In this study we analyze relative contributions to the cause and mechanism of injection-induced micro-earthquakes (MEQs) at The Geysers geothermal field, California. We estimated the potential for inducing seismicity by coupled thermal-hydrological-mechanical analysis of the geothermal steam production and cold water injection to calculate changes in stress (in time and space) and investigated if those changes could induce a rock mechanical failure and associated MEQs. An important aspect of the analysis is the concept of a rock mass that is critically stressed for shear failure. This means that shear stress in the region is near the rock-mass frictional strength, and therefore very small perturbations of the stress field can trigger an MEQ. Our analysis shows that the most important cause for injection-induced MEQs at The Geysers is cooling and associated thermal-elastic shrinkage of the rock around the injected fluid that changes the stress state in such a way that mechanical failure and seismicity can be induced. Specifically, the cooling shrinkage results in unloading and associated loss of shear strength in critically shear-stressed fractures, which are then reactivated. Thus, our analysis shows that cooling-induced shear slip along fractures is the dominant mechanism of injection-induced MEQs at The Geysers.

  11. Reservoir Simulation on the Cerro Prieto Geothermal Field: A Continuing Study

    SciTech Connect

    Castaneda, M.; Marquez, R.; Arellano, V.; Esquer, C.A.

    1983-12-15

    The Cerro Prieto geothermal field is a liquid-dominated geothermal reservoir of complex geological and hydrological structure. It is located at the southern end of the Salton-Mexicali trough which includes other geothermal anomalies as Heber and East Mesa. Although in 1973, the initial power plant installed capacity was 75 MW of electrical power, this amount increased to 180 MW in 1981 as field development continued. It is expected to have a generating capacity of 620 MW by the end of 1985, when two new plants will be completely in operation. Questions about field deliverability, reservoir life and ultimate recovery related to planned installations are being presently asked. Numerical modeling studies can give very valuable answers to these questions, even at the early stages in the development of a field. An effort to simulate the Cerro Prieto geothermal reservoir has been undergoing for almost two years. A joint project among Comision Federal de Electricidad (CFE), Instituto de Investigaciones Electricas (IIE) and Intercomp of Houstin, Texas, was created to perform reservoir engineering and simulation studies on this field. The final project objective is tosimulate the behavior of the old field region when production from additional wells located in the undeveloped field zones will be used for feeding the new power plants.

  12. The Impact of Injection on Seismicity at The Geyses, CaliforniaGeothermal Field

    SciTech Connect

    Majer, Ernest L.; Peterson, John E.

    2006-09-25

    Water injection into geothermal systems has often become arequired strategy to extended and sustain production of geothermalresources. To reduce a trend of declining pressures and increasingnon-condensable gas concentrations in steam produced from The Geysers,operators have been injecting steam condensate, local rain and streamwaters, and most recently treated wastewater piped to the field fromneighboring communities. If geothermal energy is to provide a significantincrease in energy in the United States (US Department of Energy (DOE)goal is 40,000 megawatts by 2040), injection must play a larger role inthe overall strategy, i.e., enhanced geothermal systems, (EGS). Presentedin this paper are the results of monitoring microseismicity during anincrease in injection at The Geysers field in California using data froma high-density digital microearthquake array. Although seismicity hasincreased due to increased injection it has been found to be somewhatpredicable, thus implying that intelligent injection control may be ableto control large increases in seismicity.

  13. Chemical Variations in the Rocks of La Primavera Geothermal Field (Mexico) Related with Hydrothermal Alteration

    SciTech Connect

    Prol-Ledesma, R.M.; Hernandez-Lombardini, S.I.; Lozano-Santa Cruz, R.

    1995-01-01

    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.

  14. Anthropogenic seismicity rates and operational parameters at the Salton Sea Geothermal Field.

    PubMed

    Brodsky, Emily E; Lajoie, Lia J

    2013-08-02

    Geothermal power is a growing energy source; however, efforts to increase production are tempered by concern over induced earthquakes. Although increased seismicity commonly accompanies geothermal production, induced earthquake rate cannot currently be forecast on the basis of fluid injection volumes or any other operational parameters. We show that at the Salton Sea Geothermal Field, the total volume of fluid extracted or injected tracks the long-term evolution of seismicity. After correcting for the aftershock rate, the net fluid volume (extracted-injected) provides the best correlation with seismicity in recent years. We model the background earthquake rate with a linear combination of injection and net production rates that allows us to track the secular development of the field as the number of earthquakes per fluid volume injected decreases over time.

  15. Tough2/PC application simulation project for Heber geothermal field, California, a progress report

    SciTech Connect

    Boardman, Timothy S.; Khan, M. Ali; Antunez, Emilio

    1996-01-24

    A numerical simulation model for the Heber geothermal field in Southern California is being developed under a technology transfer agreement between the Department of Energy/Lawrence Berkeley National Laboratory (LBNL) and the California Department of Conservation, Division of Oil, Gas, and Geothermal Resources (DOGGR). The main objectives of the cooperation are (1) to train DOGGR personnel in the use of the TOUGH2PC computer code; and (2) to develop a module compatible with TOUGH2 to investigate the effects of production/injection operations on the ground surface subsidence-rebound phenomenon observed in the Heber geothermal field. Initial-state calibration (undisturbed system) runs are being conducted to calibrate the model.

  16. Seismic imaging of the geothermal field at Krafla, Iceland using shear-wave splitting

    NASA Astrophysics Data System (ADS)

    Tang, Chuanhai; Rial, Jose A.; Lees, Jonathan M.

    2008-09-01

    Shear-wave splitting is emerging as a useful exploration method for geothermal reservoirs as it can detect the geometry of the fracture system, the intensity of cracking and possibly, changes in fluid pressure within the reservoir. The method is based on the analyses of polarizations and time delays of shear-waves that have been distorted by the anisotropy of the medium through which the seismic waves have propagated. Observations of shear-wave splitting within the Krafla-Leirhnúkur geothermal field, Iceland, using a 20-station 3-component portable seismic array have provided evidence for at least two major crack systems of microfractures, oriented approximately N-S and E-W. Located microearthquakes align roughly along the E-W direction of the geothermal field, with shallow focal depths mostly around the injection well, probably related to the ongoing injection. This unexpected direction is however consistent with results from a simultaneous MT (magnetotelluric) survey.

  17. Hyperspectral Thermal Infrared Analysis of the Salton Sea, CA Geothermal Field

    NASA Astrophysics Data System (ADS)

    Reath, K. A.; Ramsey, M. S.

    2011-12-01

    The Salton Sea Geothermal Field is an active 20 km2 region in southern California, which lies along the Calipatria Fault; an offshoot of the San Andreas Fault. Several geothermal fields (including the Davis-Schrimpf and Sandbar fields) and ten power plants generating 340 MW lie within this region. In order to better understand the mineral and thermal distribution of the surface, hyperspectral thermal infrared (TIR) data were acquired by Aerospace Corporation using the Spatially Enhanced Broadband Array Spectrograph System (SEABSS) airborne sensor on March 26, 2009 and April 6, 2010. SEBASS collects 128 wavelength channels at 1 meter spatial resolution, from which a new and more accurate interpretation was produced of the surface mineralogy of the geothermal fields and surrounding areas. Such data are rarely available for this type of scientific analysis and enabled the identification of mineral assemblages associated with geothermally-active areas. These minerals include anhydrite, gypsum, as well as an unknown mineral with a unique TIR wavelength feature at 8.2 μm. Comparing the 2009 and 2010 data, this unknown mineral varies in abundance and spatial distribution likely due to changes in rainfall. Samples rich in this mineral were collected from an area identified in the SEBASS data and analyzed in the laboratory using high resolution TIR emission spectroscopy. The same spectral absorption feature was found confirming the mineral's presence. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were performed on one of the samples in order to positively identify this mineral and further constrain the TIR analysis. By using the combination of airborne and laboratory spectroscopy, detailed and temporally-variable patterns of the surface mineralogy were ultimately produced. This work has the potential to be used at other geothermal sites to better characterize transient mineralogy, understand the influence of surface and ground water in these systems, and

  18. Thermal modeling of step-out targets at the Soda Lake geothermal field, Churchill County, Nevada

    NASA Astrophysics Data System (ADS)

    Dingwall, Ryan Kenneth

    Temperature data at the Soda Lake geothermal field in the southeastern Carson Sink, Nevada, highlight an intense thermal anomaly. The geothermal field produces roughly 11 MWe from two power producing facilities which are rated to 23 MWe. The low output is attributed to the inability to locate and produce sufficient volumes of fluid at adequate temperature. Additionally, the current producing area has experienced declining production temperatures over its 40 year history. Two step-out targets adjacent to the main field have been identified that have the potential to increase production and extend the life of the field. Though shallow temperatures in the two subsidiary areas are significantly less than those found within the main anomaly, measurements in deeper wells (>1,000 m) show that temperatures viable for utilization are present. High-pass filtering of the available complete Bouguer gravity data indicates that geothermal flow is present within the shallow sediments of the two subsidiary areas. Significant faulting is observed in the seismic data in both of the subsidiary areas. These structures are highlighted in the seismic similarity attribute calculated as part of this study. One possible conceptual model for the geothermal system(s) at the step-out targets indicated upflow along these faults from depth. In order to test this hypothesis, three-dimensional computer models were constructed in order to observe the temperatures that would result from geothermal flow along the observed fault planes. Results indicate that the observed faults are viable hosts for the geothermal system(s) in the step-out areas. Subsequently, these faults are proposed as targets for future exploration focus and step-out drilling.

  19. Magnetotelluric Study on the Donan Geothermal Field, Southern Part of Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Hayakawa, M.; Mogi, T.

    2016-12-01

    We performed a MT study in the Donan geothermal field where deep seated hot granitic rocks are distributing as a source of geothermal resources. But no prominent fracture zone were found in this area. Imaging a fracture zone and clarifying geothermal reservoirs are purpose of the study. Quaternary volcanoes, such as Hokkaido Komagatake and Esan in the southern part, and Karibayama in the northern part, are situated in the surroundings of the Donan area, southwestern Hokkaido, Japan. Even though recent volcanic activity is not seen in the central part, geothermal gradient is high. The geological structure of this region is dominated by the movement of basement blocks aligning in the north-south, and folds and fractures have developed. Many hot springs and geothermal manifestations are seen in this region where called "Yakumo-Nigorikawa geothermal zone." The Mori geothermal power plant, located at south area, is operating in the Nigorikawa caldera formed about 12,000 years ago. Like Nigorikawa, the Yakumo area, located at the central part of the Donan area, have been thought as promising geothermal area, and many geothermal study were performed in the 1990th. Six drilling holes were excavated and they showed that hot granitic rock are distributing at around below 1000m depth, and temperature is higher than 200 degrees in this area. We carried out new magnetotelluric (MT) survey at 20 stations in the Yakumo area. We constructed 2-D and 3-D resistivity model with MT data. Because the anomalous phases exceeding 90 degree were seen in some sites at frequency less than 0.1Hz, we only used the data at frequency range of 320Hz and 0.1Hz in this study. We used Ogawa and Uchida (1996) as a 2D inversion and Han et al. (2008) that have applied approximate sensitivity, as 3D inversion respectively. From the resistivity models, the remarkable low resistivity zone extending from deep to shallower is seen at the center of the survey area, that is inclined from south to north. A

  20. The nature of magmatism at Palinpinon geothermal field, Negros Island, Philippines: implications for geothermal activity and regional tectonics

    NASA Astrophysics Data System (ADS)

    Rae, Andrew J.; Cooke, David R.; Phillips, David; Zaide-Delfin, Maribel

    2004-01-01

    The Palinpinon geothermal field, Negros Island, Philippines is a high-temperature, liquid-dominated geothermal system in an active island-arc volcanic setting. This paper presents a regional context for the Palinpinon geology, discusses the petrogenetic evolution of magmatism in the district and assesses the genetic relationships between intrusion and geothermal circulation. The oldest rock formation, the Lower Puhagan Volcanic Formation (Middle Miocene), is part of a volcanic sequence that is traceable throughout the Visayas region and is related to subduction of the Sulu Sea oceanic basin in a southeasterly direction beneath the Sulu arc. Late Miocene to Early Pliocene times mark a period of regional subsidence and marine sedimentation. A thick sequence of calcareous sediments (Okoy Formation) was deposited during this period. Magmatism in Early Pliocene to Recent times coincided with commencement of subduction at the Negros-Sulu Arc. This produced basaltic andesites and andesites belonging to the Southern Negros and Cuernos Volcanic Formations. During this time the Puhagan dikes and the Nasuji Pluton intruded Middle Miocene, Late Miocene and Early-Late Pliocene formations. Based on radiogenic ( 40Ar/ 39Ar) dating of hornblende, the Puhagan dikes are 4.1-4.2 Ma and the Nasuji Pluton 0.3-0.7 Ma. This age difference confirms these intrusions are not genetically related. The Early Pliocene age of the Puhagan dikes also confirms they are not the heat source for the current geothermal system and that a much younger intrusion is situated beyond drill depths. Igneous rock formations in southern Negros are the products of regional island-arc magmatism with medium K, calc-alkaline, basaltic to dacitic compositions. Their adakitic affinity implies that the melting of subducted oceanic basalt has influenced magmatism in this region. Considering the regional tectonic history the most likely scenarios for the generation of slab melts are: (1) during the Middle Miocene, by the

  1. Repeat Absolute and Relative Gravity Measurements for Geothermal Reservoir Monitoring in the Ogiri Geothermal Field, Southern Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Nishijima, J.; Umeda, C.; Fujimitsu, Y.; Takayama, J.; Hiraga, N.; Higuchi, S.

    2016-09-01

    Repeat hybrid microgravity measurements were conducted around the Ogiri Geothermal Field on the western slope of Kirishima volcano, southern Kyushu, Japan. This study was undertaken to detect the short-term gravity change caused by the temporary shutdown of production and reinjection wells for regular maintenance in 2011 and 2013. Repeat microgravity measurements were taken using an A-10 absolute gravimeter (Micro-g LaCoste) and CG-5 gravimeter (Scintrex) before and after regular maintenance. Both instruments had an accuracy of 10 μgal. The gravity stations were established at 27 stations (two stations for absolute measurements and 25 stations for relative measurements). After removal of noise effects (e.g., tidal movement, precipitation, shallow groundwater level changes), the residual gravity changes were subdivided into five types of response. We detected a gravity decrease (up to 20 μgal) in the reinjection area and a gravity increase (up to 30 μgal) in the production area 1 month after the temporary shutdown. Most of the gravity stations recovered after the maintenance. The temporal density changes in the geothermal reservoir were estimated based on these gravity changes.

  2. Prospects of development of highly mineralized high-temperature resources of the Tarumovskoye geothermal field

    NASA Astrophysics Data System (ADS)

    Alkhasov, A. B.; Alkhasova, D. A.; Ramazanov, A. Sh.; Kasparova, M. A.

    2016-06-01

    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

  3. Measured ground-surface movements, Cerro Prieto geothermal field

    SciTech Connect

    Massey, B.L.

    1981-01-01

    The Cerro Prieto geothermal area in the Mexicali Valley, 30 kilometers southeast of Mexicali, Baja California, incurred slight deformation because of the extraction of hot water and steam, and probably, active tectonism. During 1977 to 1978, the US Geological Survey established and measured two networks of horizontal control in an effort to define both types of movement. These networks consisted of: (1) a regional trilateration net brought into the mountain ranges west of the geothermal area from stations on an existing US Geological Survey crustal-strain network north of the international border; and (2) a local net tied to stations in the regional net and encompassing the present and planned geothermal production area. Electronic distance measuring instruments were used to measure the distances between stations in both networks in 1978, 1979 and 1981. Lines in the regional net averaged 25 km. in length and the standard deviation of an individual measurement is estimated to be approx. 0.3 part per million of line length. The local network was measured using different instrumentation and techniques. The average line length was about 5 km. and the standard deviation of an individual measurement approached 3 parts per million per line length. Ground-surface movements in the regional net, as measured by both the 1979 and 1981 resurveys, were small and did not exceed the noise level. The 1979 resurvey of the local net showed an apparent movement of 2 to 3 centimeters inward toward the center of the production area. This apparent movement was restricted to the general limits of the production area. The 1981 resurvey of the local net did not show increased movement attributable to fluid extraction.

  4. Electrical resistivity investigations at the Olkaria geothermal field, Kenya

    SciTech Connect

    Bhogal, P.S.

    1980-09-01

    The bipole-dipole, Schlumberger and in line dipole-dipole electrical resistivity configurations were used to delineate the Olkaria geothermal reservoir with the view to site boreholes for the production of electric power using the geopressurized hot water. The dipole-dipole resistivity data provided the least ambiguous and most usable data for assessing the resource. Deep drilling into two of the anomalies outlined by this survey has proved the existence of high-temperature reservoirs and a 15MW power station is under construction.

  5. Temperature gradient drilling in the Las Cruces East Mesa geothermal field

    SciTech Connect

    Lohse, R.L.; Icerman, L.

    1982-10-01

    Thirty-four shallow temperature gradient holes were drilled on the Las Cruces east mesa adjacent to the Las Alturas geothermal anomaly. Temperature and heat flow data indicate that the anomaly, now named the Las Cruces East Mesa Geothermal Field, is at least 75 km/sup 2/ in size. These data together with geological and geophysical data collected previously suggest that the hydrothermal system is fault controlled and is composed of NW-SE and N-S components, which give the system an apparent NNW-SSE trend.

  6. Use of slim holes for reservoir evaluation at the Steamboat Hills Geothermal Field, Nevada, USA

    SciTech Connect

    Combs, Jim; Goranson, Colin

    1994-01-20

    Three slim holes were drilled at the Steamboat Hills Geothermal Field in northwestern Nevada about 15 km south of Reno. The slim holes were drilled to investigate the geologic conditions, thermal regime and productive characteristics of the geothermal system. They were completed through a geologic sequence consisting of alluvium cemented by geothermal fluids, volcaniclastic materials, and granodiorite. Numerous fractures, mostly sealed, were encountered throughout the drilled depth; however, several open fractures in the granodiorite, dipping between 65 and 90{degree}, had apertures up to 13 mm in width. The depths of the slim holes vary from 262 to 277 m with open-hole diameters of 76 mm. Pressure and temperature logs gave bottom-hole temperatures ranging from 163 to 166{degree} C. During injection testing, downhole pressures were measured using capillary tubing with a surface quartz transducer while temperatures were measured with a Kuster temperature tool located below the capillary tubing pressure chamber. No pressure increase was measured at reservoir depths in any of the three slim holes while injecting 11 kg/s of 29{degree}C water indicating a very high permeability in the geothermal reservoir. These injection test results suggested that productive geothermal fluids could be found at depths sufficient for well pumping equipment and at temperatures needed for electrical power production using binary-type conversion technology.

  7. Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge Hydrothermal Vents

    DOE Data Explorer

    Andrew Fowler

    2015-10-01

    Compilation of rare earth element and associated major and minor dissolved constituent analytical data for USA geothermal fields and global seafloor hydrothermal vents. Data is in original units. Reference to and use of this data should be attributed to the original authors and publications according to the provisions outlined therein.

  8. Long-term Evolution of Seismicity Rates in California Geothermal Fields

    NASA Astrophysics Data System (ADS)

    Trugman, D. T.; Shearer, P. M.; Borsa, A. A.; Fialko, Y. A.

    2015-12-01

    The temporal evolution of seismicity rates within geothermal fields provides important observational constraints on the ways in which rocks respond to natural and anthropogenic loading. We develop an iterative, regularized inversion procedure to partition the observed seismicity rate into two primary components: (1) the interaction seismicity rate due to earthquake-earthquake triggering, and (2) the time-varying background seismicity rate controlled by other time-dependent stresses, including anthropogenic forcing. We parameterize our seismicity model using an Epidemic-Type Aftershock Sequence (ETAS) framework with a background seismicity rate that varies smoothly with time. We apply our methodology to study long-term changes in seismicity rates at the Geysers and Salton Sea geothermal fields in California. At the Geysers, we find that the background seismicity rate is highly correlated with fluid injection. Seismicity at the Geysers has experienced a rate increase of approximately 50% since year 2000 and exhibits strong seasonal fluctuations, both of which can be explained by changes in fluid injection following the completion of the Santa Rosa pipeline. At the Salton Sea, the background seismicity rate has remained relatively stable since 1990, with short-term fluctuations that are not obviously modulated by fluid fluxes related to the operation of the geothermal field. The differences in the field-wide seismicity responses of the Geysers and Salton Sea to geothermal plant operation may reflect differences in in-situ reservoir conditions and local tectonics, indicating that induced seismicity may not be solely a function of fluid injection and withdrawal.

  9. Attenuation tomography using microearthquake (MEQ) data in the "A" geothermal field

    NASA Astrophysics Data System (ADS)

    Hasanah, Mia Uswatun; Nugraha, Andri Dian; Sule, Rachmat

    2013-09-01

    Attenuation is a physical parameter of rock that can reflect the geological conditions beneath the earth's surface. We conducted attenuation tomographic imaging in the "A" geothermal field by using microearthquake (MEQ) data. We applied a method of spectral fitting to invert the t* value. For the attenuation tomographic inversion, we used the initial 3-D velocity model from the previous study in the region. Our study shows that the value of Qp, Qs and Qp/Qs ratio in the geothermal field is an important parameter for interpreting the subsurface structure. The "A" geothermal field in this study lies between several active and dormant volcanoes in West Java Province, Indonesia. This geothermal field already produces electricity of more than 220 MWe. The hydraulic stimulation has been carried out from the end of 2007 until the beginning of 2008. This experiment was carried out in order to get an understanding about the orientation of weak or fractures zones in the subsurface, so that the strategy of future exploration and well targeting could be estimated. We interpreted the joint immaging result of Qp, Qs and Qp/Qs ratio with previous seismic velocities (Vp, Vs and Vp/Vs ratio) tomography result. We can see that the high attenuation value (low Q value) and low velocity anomaly structures may associated to fluid filled rock and also fault segment.

  10. Summary of recent progress in understanding the Cerro Prieto Geothermal Field, Baja, California, Mexico

    SciTech Connect

    Lippmann, M.J.; Witherspoon, P.A.

    1980-07-01

    Geological and geophysical studies indicate that the Cerro Prieto reservoir is quite heterogeneous due to complex lithofacies fault structures, and hydrothermal alteration. Geochemical investigations have provided clues on the origin of the geothermal fluids, their recharge paths and on the reservoir processes accompanying the exploitation of the field. Well tests have yielded information on the permeability of the reservoir. (MHR)

  11. The possibilities of utilisation of heat from Tattapani Geothermal field, India

    SciTech Connect

    Sarolkar, P.B.; Pitale, U.L.

    1996-12-31

    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.

  12. Microearthquake source mechanism studies at the Geysers geothermal field

    SciTech Connect

    Kirkpatrick, A.; Romero, A. Jr.; Peterson, J. Jr.; Johnson, L.; Majer, E.

    1996-04-01

    In this paper the authors discuss moment tensors obtained from inversion of MEQ waveform data recorded at the Southeast (SE) and Northwest (NW) Geysers geothermal areas by the high-resolution seismic networks operated by Lawrence Berkeley National Laboratory (Berkeley Lab) and the Coldwater Creek Geothermal Company (now CCPA). The network in the SE Geysers consists of 13 high-frequency (4.5 Hz), digital (480 samples), three-component, telemetered stations deployed on the surface in portions of the Calpine, Unocal-NEC-Thermal (U-N-T), and Northern California Power Agency (NCPA) leases. The network in the NW Geysers is a 16-station borehole array of three-component geophones (4.5 Hz), digital at 400 samples/sec, and telemetered to a central site. One of the main objectives of Berkeley Lab`s program at the Geysers is to assess the utility of MEQ monitoring as a reservoir management tool. Discrimination of the mechanisms of these events may aid in the interpretation of MEQ occurrence patterns and their significance to reservoir processes and conditions of interest to reservoir managers. Better understanding of the types of failure deduced from source mechanism studies, and their relations to production parameters, should also lead to a better understanding of the effects of injection and withdrawal.

  13. Pressure-interference testing of the Sumikawa geothermal field

    SciTech Connect

    Garg, S.K.; Pritchett, J.W.; Ariki, K.; Kawano, Y.

    1991-01-01

    Pressure interference tests have been used to determine the permeability structure of the Sumikawa reservoir. Interference tests between wells S-4 and KY-1 have indicated the presence of a very high permeability (140 md) north-south channel in the altered andesite layer. Pressure buildup data from well SN-7D have provided indications of a high transmissivity (kh {approx} 18 darcy-meters) reservoir located in the granodiorite layer, lack of pressure response in nearby shutin Sumikawa wells implies that the reservoir penetrated by SN-7D is isolated from the shallower reservoir in the altered andesites. The ''altered andesite'' and the ''granodiorite'' formations constitute the principal geothermal aquifers at Sumikawa. Pressure interference tests (wells KY-1 and SB-2, and wells KY-2 and SB-3) have also confirmed the presence of moderately high transmissivity ({approx} 2 darcy-meters) dacitic layers in the ''marine-volcanic complex'' formation. Because of its low vertical permeability, the ''marine volcanic complex'' formation constitutes an attractive target for the reinjection of waste geothermal fluids.

  14. 3-D analysis and interpretation of magnetotelluric data from the Aluto-Langano geothermal field, Ethiopia

    NASA Astrophysics Data System (ADS)

    Samrock, F.; Kuvshinov, A.; Bakker, J.; Jackson, A.; Fisseha, S.

    2015-09-01

    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.

  15. Feasibility of Geothermal Energy Extraction from Non-Activated Petroleum Wells in Arun Field

    NASA Astrophysics Data System (ADS)

    Syarifudin, M.; Octavius, F.; Maurice, K.

    2016-09-01

    The big obstacle to develop geothermal is frequently came from the economical viewpoint which mostly contributed by the drilling cost. However, it potentially be tackled by converting the existing decommissioned petroleum well to be converted for geothermal purposes. In Arun Field, Aceh, there are 188 wells and 62% of them are inactive (2013). The major obstacle is that the outlet water temperature from this conversion setup will not as high as the temperature that come out from the conventional geothermal well, since it will only range from 60 to 180oC depending on several key parameters such as the values of ground temperature, geothermal gradient in current location, the flow inside of the tubes, and type of the tubes (the effect from these parameters are studied). It will just be considered as low to medium temperature, according to geothermal well classification. Several adjustments has to be made such as putting out pipes inside the well that have been used to lift the oil/gas and replacing them with a curly long coil tubing which act as a heat exchanger. It will convert the cold water from the surface to be indirectly heated by the hot rock at the bottom of the well in a closed loop system. In order to make power production, the binary cycle system is used so that the low to medium temperature fluid is able to generate electricity. Based on this study, producing geothermal energy for direct use and electricity generation in Arun Field is technically possible. In this study case, we conclude that 2900 kW of electricity could be generated. While for-direct utility, a lot of local industries in Northern Sumatera could get the benefits from this innovation.

  16. Elevated carbon dioxide flux at the Dixie Valley geothermal field, Nevada; relations between surface phenomena and the geothermal reservoir

    USGS Publications Warehouse

    Bergfeld, D.; Goff, F.; Janik, C.J.

    2001-01-01

    In the later part of the 1990s, a large die-off of desert shrubs occurred over an approximately 1 km2 area in the northwestern section of the Dixie Valley (DV) geothermal field. This paper reports results from accumulation-chamber measurements of soil CO2 flux from locations in the dead zone and stable isotope and chemical data on fluids from fumaroles, shallow wells, and geothermal production wells within and adjacent to the dead zone. A cumulative probability plot shows three types of flux sites within the dead zone: Locations with a normal background CO2 flux (7 g m-2 day-1); moderate flux sites displaying "excess" geothermal flux; and high flux sites near young vents and fumaroles. A maximum CO2 flux of 570 g m-2 day-1 was measured at a location adjacent to a fumarole. Using statistical methods appropriate for lognormally distributed populations of data, estimates of the geothermal flux range from 7.5 t day-1 from a 0.14-km2 site near the Stillwater Fault to 0.1 t day-1 from a 0.01 -km2 location of steaming ground on the valley floor. Anomalous CO2 flux is positively correlated with shallow temperature anomalies. The anomalous flux associated with the entire dead zone area declined about 35% over a 6-month period. The decline was most notable at a hot zone located on an alluvial fan and in the SG located on the valley floor. Gas geochemistry indicates that older established fumaroles along the Stillwater Fault and a 2-year-old vent in the lower section of the dead zone discharge a mixture of geothermal gases and air or gases from air-saturated meteoric water (ASMW). Stable isotope data indicate that steam from the smaller fumaroles is produced by ??? 100??C boiling of these mixed fluids and reservoir fluid. Steam from the Senator fumarole (SF) and from shallow wells penetrating the dead zone are probably derived by 140??C to 160??C boiling of reservoir fluid. Carbon-13 isotope data suggest that the reservoir CO2 is produced mainly by thermal decarbonation of

  17. Open Questions on the Origin of Life at Anoxic Geothermal Fields

    NASA Astrophysics Data System (ADS)

    Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.

    2012-10-01

    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.

  18. Thermal Modeling of an Area N-W of the Larderello Geothermal Field, Italy.

    NASA Astrophysics Data System (ADS)

    Bellani, S.; Gherardi, F.

    2008-12-01

    A wide area enclosed between the ancient Etruscan town of Volterra and the northern rim of the Larderello high enthalpy geothermal field (Tuscany, Italy) shows thermal features which suggest further investigations aimed at mid-low enthalpy geothermal energy exploitation. Thermal gradients are in the range 75 - 100 C°/km, while surface heat flow spans between 100 - 150 mW/m2. Numerical simulations were performed to predict the spatial distribution of temperature and fluid circulation paths, constrained by field data. Temperature control based on real data is allowed by a few deep exploratory geothermal wells along with several shallower gradient wells, down to a maximum of about 3 km. The model domain extends over an area 20 by 10 km; thickness is 6 km. Local geology is simplified in four different terrains, according to the generalized stratigraphy of the area. Several sets of simulations were carried out running SHEMAT and TOUGH2 numerical codes, considering various boundary conditions, inner geometries and hydraulic permeabilities. The model was realized by means of unsteady forward simulations, under the assumptions of impervious and isothermal top and bottom boundaries, lateral adiabatic faces and variable internal physical properties. The results indicate that the present temperature and pressure distribution of hot fluids with depth in the northern border area of the Larderello field allows to hypothesize a fruitful exploitation of the medium- enthalpy geothermal resources, possibly with low-boiling point fluids binary plants for electricity generation.

  19. Initial Measurements of Petrophysical Properties on Rocks from the Los Azufres, Mexico, Geothermal Field

    SciTech Connect

    Contreras, E.; Iglesias, E.; Razo, E.

    1986-01-21

    Petrophysical properties of geothermal reservoir rocks are valuable information for many activities, including reservoir characterization, modeling, field test analysis and planning of exploitation techniques. Petrophysical data of rocks from geothermal reservoirs located in volcanic areas is in general very scarce. In particular, no petrophysical data of rocks from the Los Azufres geothermal field area has ever been published. This work presents the results of initial petrophysical studies on outcrop rocks and drill core samples from the Los Azufres geothermal field. These studies are the first part of an ongoing experimental program intended to establish a data-base about physical properties of the Los Azufres rocks, in support of the many reservoir engineering activities which require of such information. The experimental work carried out consisted of laboratory measurements of density, porosity, permeability, compressibility, thermal conductivity, thermal expansion, electrical resistivity and sonic wave velocities. Some of the experiments were aimed at investigation of the effects of temperature, pressure, saturation and other parameters on the physical properties of rocks.

  20. Open Questions on the Origin of Life at Anoxic Geothermal Fields

    PubMed Central

    Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.

    2014-01-01

    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+, 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 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 as a tool, 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. PMID:23132762

  1. Small-Scale Geothermal Power Plant Field Verification Projects: Preprint

    SciTech Connect

    Kutscher, C.

    2001-07-03

    In the spring of 2000, the National Renewable Energy Laboratory issued a Request for Proposal for the construction of small-scale (300 kilowatt [kW] to 1 megawatt [MW]) geothermal power plants in the western United States. Five projects were selected for funding. Of these five, subcontracts have been completed for three, and preliminary design work is being conducted. The three projects currently under contract represent a variety of concepts and locations: a 1-MW evaporatively enhanced, air-cooled binary-cycle plant in Nevada; a 1-MW water-cooled Kalina-cycle plant in New Mexico; and a 750-kW low-temperature flash plant in Utah. All three also incorporate direct heating: onion dehydration, heating for a fish hatchery, and greenhouse heating, respectively. These projects are expected to begin operation between April 2002 and September 2003. In each case, detailed data on performance and costs will be taken over a 3-year period.

  2. Brine treatment test for reinjection on Cerro Prieto geothermal field

    SciTech Connect

    Hurtado, R.; Mercado, S.; Gamino, H. )

    1989-01-01

    Reinjection of disposal brine from the Cerro Prieto Geothermal Power Plant System is attractive mainly because, on top of solving the brine disposal problem, it may significantly contribute to extend the reservoir useful lifetime, through thermal and hydraulic recharge. Because the high concentration of colloidal silica in the disposal brine, laboratory and pilot plant tests were conducted in order to develop the brine treatment process. Addition of 20-40 mg/1 lime to flashed and aged brine for 10-20 minutes yields a clarified brine relatively low in suspended solids (10-30 mg/1) when the over flow rate is 38.5 1/min-m/sup 2/. 1.1 mills/kWh was the estimated cost for treatment of 800 kg/s of separated brine from the Cerro Prieto I power station.

  3. Groundwater contamination mechanism in a geothermal field: A case study of Balcova, Turkey

    NASA Astrophysics Data System (ADS)

    Aksoy, Niyazi; Şimşek, Celalettin; Gunduz, Orhan

    2009-01-01

    The Balcova Geothermal Field (BGF) located in Izmir, Turkey is situated on an east-west directed graben plain within which the hot waters surface from a fault zone that cuts the Mesozoic aged Bornova Flysch. Due to the low permeability and porosity of the Bornova Flysch, the geothermal water cycles along the immediate vicinity of the Agamemnon fault and mixes with cold waters at different depths of this fractured zone. Within the scope of this study, the mixing patterns and the groundwater contamination mechanisms are analyzed by, hydrogeological and hydrogeochemical methods. Based on the results of this research, it has been found out that the hot geothermal water and the cold regional groundwater resources of the surficial aquifer mix within the fractured zone in Bornova Flysch and within the Quaternary alluvium aquifer due to natural and anthropogenic activities including (i) the natural upward movement of geothermal fluid along the fault line, (ii) the accelerated upward seepage of geothermal fluid from faulty constructed boreholes drilled in the area, (iii) the faulty reinjection applications; and, (iv) the uncontrolled discharge of waste geothermal fluid to the natural drainage network. As a result of these activities, the cold groundwater reserves of the alluvial aquifer are contaminated thermally and chemically in such a way that various toxic chemicals including arsenic, antimony and boron are introduced to the heavily used surficial aquifer waters hindering their use for human consumption and agricultural irrigation. Furthermore, the excessive pumping from the surficial aquifer as well as the reduced surface water inflow into BGF due to the dam constructed on Ilica Creek intensify the detrimental effects of this contamination. Based on the results of this study, it can be concluded that the groundwater pollution in BGF will expand and reach to the levels of no return unless a series of preventive measures is taken immediately.

  4. Groundwater contamination mechanism in a geothermal field: a case study of Balcova, Turkey.

    PubMed

    Aksoy, Niyazi; Simşek, Celalettin; Gunduz, Orhan

    2009-01-07

    The Balcova Geothermal Field (BGF) located in Izmir, Turkey is situated on an east-west directed graben plain within which the hot waters surface from a fault zone that cuts the Mesozoic aged Bornova Flysch. Due to the low permeability and porosity of the Bornova Flysch, the geothermal water cycles along the immediate vicinity of the Agamemnon fault and mixes with cold waters at different depths of this fractured zone. Within the scope of this study, the mixing patterns and the groundwater contamination mechanisms are analyzed by, hydrogeological and hydrogeochemical methods. Based on the results of this research, it has been found out that the hot geothermal water and the cold regional groundwater resources of the surficial aquifer mix within the fractured zone in Bornova Flysch and within the Quaternary alluvium aquifer due to natural and anthropogenic activities including (i) the natural upward movement of geothermal fluid along the fault line, (ii) the accelerated upward seepage of geothermal fluid from faulty constructed boreholes drilled in the area, (iii) the faulty reinjection applications; and, (iv) the uncontrolled discharge of waste geothermal fluid to the natural drainage network. As a result of these activities, the cold groundwater reserves of the alluvial aquifer are contaminated thermally and chemically in such a way that various toxic chemicals including arsenic, antimony and boron are introduced to the heavily used surficial aquifer waters hindering their use for human consumption and agricultural irrigation. Furthermore, the excessive pumping from the surficial aquifer as well as the reduced surface water inflow into BGF due to the dam constructed on Ilica Creek intensify the detrimental effects of this contamination. Based on the results of this study, it can be concluded that the groundwater pollution in BGF will expand and reach to the levels of no return unless a series of preventive measures is taken immediately.

  5. Geological control on the reservoir characteristics of Olkaria West Geothermal Field, Kenya

    SciTech Connect

    Omenda, Peter A.

    1994-01-20

    The reservoir of the West Olkaria Geothermal Field is hosted within tuffs and the reservoir fluid is characterized by higher concentrations of reservoir CO{sub 2} (10,000-100,000 mg/kg) but lower chloride concentrations of about 200 mg/kg than the East and North East Fields. The West Field is in the outflow and main recharge area of the Olkaria geothermal system. Permeability is generally low in the West Field and its distribution is strongly controlled by the structures. Fault zones show higher permeability with wells drilled within the structures havin larger total mass outputs. However, N-S and NW-SE faults are mainly channels for cold water downflow into the reservoir. Well feeder zones occur mostly at lava-tuff contacts; within fractured lava flows and at the contacts of intrusives and host rocks.

  6. 36Cl/Cl ratios in geothermal systems: preliminary measurements from the Coso Field

    SciTech Connect

    Nimz, G.J.; Moore, J.N.; Kasameyer, P.W.

    1997-07-01

    The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results indicate that most of the chlorine is not derived from the dominant granitoid that host the geothermal system. If the chlorine was originally input into the Coso subsurface through meteoric recharge, that input occurred at least 1-1.25 million years ago. The results suggest that the thermal waters could be connate waters derived from sedimentary formations, presumably underlying and adjacent top the granitic rocks, which have recently migrated into the host rocks. Alternatively, most of the chlorine but not the water, may have recently input into the system from magmatic sources. In either case, the results indicate that most of the chlorine in the thermal waters has existed within the granitoid host rocks for no more than about 100,00-200,00 years. this residence time for the chlorine is similar to residence times suggested by other researchers for chlorine in deep groundwaters of the Mono Basin north of the Coso field.

  7. Inverse modeling and forecasting for the exploitation of the Pauzhetsky geothermal field, Kamchatka, Russia

    SciTech Connect

    Finsterle, Stefan; Kiryukhin, A.V.; Asaulova, N.P.; Finsterle, S.

    2008-04-01

    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.

  8. Sustainable energy development and water supply security in Kamojang Geothermal Field: The Energy-Water Nexus

    NASA Astrophysics Data System (ADS)

    Sofyan, Y.; Nishijima, J.; Fujimitsu, Y.

    2014-12-01

    The Kamojang Geothermal Field (KGF) is a typical vapor dominated hydrothermal system in West Java, Indonesia. This geothermal field is the oldest exploited geothermal field in Indonesia. From 1983 to 2005, more than 160 million tons of steam have been exploited from the KGF and more than 30 million tons of water were injected into the reservoir system. The injected water come from condensed water, local river and ground water. Sustainable production in the geothermal energy development is the ability of the production system applied to sustain the stable production level over long times and to manage the mass balance between production, injection and natural recharge in the geothermal reservoir during exploitation. Mass balance in the reservoir system can be monitored by using time lapse gravity monitoring. Mass variation of hydrodynamic in the reservoir of KGF from 1999 to 2005 is about -3.34 Mt/year while is about -3.78 Mt/year from 1999 to 2008. Another period between 2009 and 2010, mass variation decreased about -8.24 Mt. According to the history of production and injection, natural recharge to the KGF's reservoir is estimated at about 2.77 Mt/year from 1999 to 2005 and 2.75 Mt/year from 1999 to 2008. Between 2009 and 2010, KGF has a bigger mass deficiency rate throughout 200 MWe maintain production. Large amount of fresh water is needed for sustainable geothermal energy production, while the domestic water supply need is also increased. Natural recharge, about 50% of injected water, cooling system, drilling and other production activities in KGF spend large amounts of fresh water. Water consumption for local people around KGF is about 1.46 MT/year. The water volume around KGF of total runoff is the range between dry season 0.07 MT/month and rainy season 4.4 MT/month. The water demands for sustainable geothermal production of KGF and for local people's consumption will increase in the future. Integrated planning between the energy and water sectors in KGF

  9. Did stresses from the Cerro Prieto Geothermal Field influence the El Mayor-Cucapah rupture sequence?

    NASA Astrophysics Data System (ADS)

    Trugman, Daniel T.; Borsa, Adrian A.; Sandwell, David T.

    2014-12-01

    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.

  10. Stress, faulting and fluid flow in the Coso Geothermal Field, CA

    NASA Astrophysics Data System (ADS)

    Davatzes, N. C.; Hickman, S.

    2006-12-01

    We integrate new geologic mapping and new in situ measurements of stress orientations and magnitudes from studies of wells within and on the flanks of the geothermal system with existing data sets to refine a geomechanical model for the Coso geothermal field. Stress orientations (averaged from several hundred to thousand meters of vertical borehole data) in wells across the field are fairly uniform and are consistent with focal mechanism inversions of earthquake clusters for stress and incremental strain. Active faults trending NNW-SSE to NNE-SSW are well oriented for normal slip in the current stress field, where the mean least principal horizontal compressive stress, Shmin, orientation is 108° ± 24º in a transitional strike-slip to normal faulting stress regime. These structures bound regions of intense micro-seismicity and are complexly associated with surface hydrothermal activity. WNW-ESE trending faults are also associated with distinct regions of enhanced seismicity but are only associated with surface hydrothermal activity where they intersect more northerly trending normal faults. These faults show no evidence for Quaternary slip at the surface and are poorly oriented in the modern stress field. These results together with stress magnitudes measured in the East Flank of the field suggest that the most productive portions of the Coso geothermal field are in high deviatoric stress environments conducive to normal faulting. Recent earthquake relocations and incremental strain inversions map areas of extensional strain located over the southern part of the Main Field and reaching east and north into the East Flank consistent with our borehole analyses. The resulting relatively low mean stress is conducive to dilation and increased permeability accompanying fault slip and coincides with the hottest areas in the geothermal field. Similar regions of locally reduced mean stress might arise from mechanical interaction during slip on intersecting fault segments

  11. Structural Controls of Neal Hot Springs Geothermal Field, Malhuer County, Oregon

    NASA Astrophysics Data System (ADS)

    Edwards, J. H.; Faulds, J. E.

    2012-12-01

    Detailed mapping (1:24,000) of the Neal Hot Springs area (90 km2) in eastern Oregon is part of a larger study of geothermal systems in the Basin and Range, which focuses on the structural controls of geothermal activity. The study area lies within the intersection of two regional grabens, the middle-late Miocene, N-striking, Oregon-Idaho graben and younger late Miocene to Holocene, NW-striking, western Snake River Plain graben. The geothermal field is marked by Neal Hot Springs, which effuse from opaline sinter mounds just north of Bully Creek. Wells producing geothermal fluids, with temperatures at 138°C, intersect a major, W-dipping, NNW-striking, high-angle normal fault at depths of 850-915 m. Displacement along this structure dies southward, with likely horse-tailing, which commonly produces high fracture density and a zone of high permeability conducive for channeling hydrothermal fluids. Mapping reveals that the geothermal resource lies within a local, left step-over. 'Hard-linkage' between strands of the left-stepping normal fault, revealed through a study of well chips and well logs, occurs through two concealed structures. Both are W-striking faults, with one that runs parallel to Cottonwood Creek and one 0.5 km N of the creek. Injection wells intersect these two transverse structures within the step-over. Stepping and displacement continue to the NW of the known geothermal field, along W-dipping, N-striking faults that cut lower to middle Miocene Hog Creek Formation, consisting of silicic and mafic volcanic rocks. These N-striking faults were likely initiated during initial Oregon-Idaho graben subsidence (15.3-15.1 Ma), with continued development through late Miocene. Bully Creek Formation deposits, middle to upper Miocene lacustrine and pyroclastic rocks, concomitantly filled the sub half-grabens, and they dip gently to moderately eastward. Younger, western Snake River Plain deposits, upper Miocene to Pliocene fluvial, lacustrine, and pyroclastic rocks

  12. Results of investigations at the Zunil geothermal field, Guatemala: Well logging and brine geochemistry

    SciTech Connect

    Adams, A.; Dennis, B.; Van Eeckhout, E.; Goff, F.; Lawton, R.; Trujillo, P.E.; Counce, D.; Archuleta, J. ); Medina, V. . Unidad de Desarollo Geotermico)

    1991-07-01

    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.

  13. Reservoir simulation studies: Wairakei Geothermal Field, New Zealand. Final report

    SciTech Connect

    Pritchett, J.W.; Rice, L.F.; Garg, S.K.

    1980-01-01

    Numerical reservoir simulation techniques were used to perform a history-match of the Wairakei geothermal system in New Zealand. First, a one-dimensional (vertical) model was chosen; realistic stratigraphy was incorporated and the known production history was imposed. The effects of surface and deep recharge were included. Good matches were obtained, both for the reservoir pressure decline history and changes in average discharge enthalpy with time. Next, multidimensional effects were incorporated by treating with a two-dimensional vertical section. Again, good history matches were obtained, although computed late-time discharge enthalpies were slightly high. It is believed that this disparity arises from inherently three-dimensional effects. Predictive calculations using the two-dimensional model suggest that continued future production will cause little additional reservoir pressure drop, but that thermal degradation will occur. Finally, ground subsidence data at Wairakei was examined. It was concluded that traditional elastic pore-collapse models based on classical soil-mechanics concepts are inadequate to explain the observed surface deformation. It is speculated that the measured subsidence may be due to structural effects such as aseismic slippage of a buried reservoir boundary fault.

  14. 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

    SciTech Connect

    Garg, S.K.; Combs, J.; Pritchett, J.W.

    1997-07-01

    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).

  15. Fracture mapping in geothermal fields with long-offset induction logging

    SciTech Connect

    Wilt, M.; Takasugi, Shinji; Uchida, Toshihiro

    1997-12-31

    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.

  16. Pre- and post-exploitation variations in hydrothermal activity in Los Humeros geothermal field, Mexico

    NASA Astrophysics Data System (ADS)

    Prol-Ledesma, R. M.

    1998-08-01

    Los Humeros geothermal field is a remarkable example of the lack of water-rock equilibrium. Significant variations of hydrothermal activity have occurred before and after exploitation started. Presently, discharged water is not in equilibrium with the alteration suite observed in the reservoir rocks. Hydrothermal minerals identified in core and cuttings define the occurrence of several stages of hydrothermal activity. Cooling at depth is inferred from fluid inclusion and alteration mineralogy data from the wells located nearby Los Humeros fault. Most wells produce a two-phase fluid with excess enthalpy, this accounts for the high CO 2 content observed in the discharged fluid. Sulfur and carbon isotopic data indicate that volatile species in the geothermal fluid have magmatic as well as sedimentary components, while strontium isotopic composition shows that calcium is provided by the andesitic rocks that form the reservoir. As exploitation of the field started, concentration of HCl increased in the discharged fluids. This shows that recharge of the reservoir is not enough to balance the output for production, and drying out of the field may be taking place at depth. The lack of chemical equilibrium and the presence of gases of magmatic origin suggest that Los Humeros is a relatively young geothermal field related to a recent magmatic intrusion.

  17. Connecting Anthropogenic Seismicity Rates To Operational Parameters At The Salton Sea Geothermal Field, Southern California (Invited)

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Lajoie, L. J.

    2013-12-01

    Geothermal power is generated at several major volcanic fields in California. As efforts to monitor seismicity increase, methods to understand the anthropogenic component need to improve. Ideally, induced earthquake rate should be forecast based on publicly-reported volumes of fluid injection or other operational parameters. At the flash facilities in the Salton Sea Geothermal Field, the total volume of fluid extracted or injected tracks the long-term evolution of seismicity. However, for recent years net fluid volume (extracted-injected) is better correlated with seismicity. After correcting for the variable aftershock rate using an Epidemic-Type Aftershock Sequence model (ETAS), we fit the background earthquake rate with a linear combination of injection and net production rate that allows us to track the secular evolution of the field. The number of earthquakes per fluid volume injected decreases gradually over time. In the Salton Sea Geothermal Field, the new analysis of induced seismicity provides a template for future evaluation of hazard directly based on measureable, controllable operational quantities. The interactions of these anthropogenic events with the larger-scale tectonic and volcanic systems remains to be investigated. Results of the linear model of seismicity based on a combination of net production and injection. (a) Example of observed seismicity rate and model prediction using the reported fluid data and the best-fit linear model. (b) Number of earthquakes triggered per net volume of fluid extracted or total fluid injection.

  18. Geology and geothermal origin of Grant Canyon and Bacon Flat Oil Fields, Railroad Valley, Nevada

    SciTech Connect

    Hulen, J.B. ); Goff, F. ); Ross, J.R. ); Bortz, L.C. ); Bereskin, S.R. )

    1994-04-01

    Eastern Nevada's Grant Canyon and Bacon Flat oil fields show strong evidence of formation in a still-active, moderate-temperature geothermal system. Modern manifestations of this system include unusually elevated oil-reservoir temperature at shallow depth, 116-122[degrees]C at 1.1-1.6 km, and dilute Na-HCO[sub 3]Cl thermal waters directly associated with hot oil. Hydrogen and oxygen isotopic compositions indicate that these thermal waters are meteoric in origin, but were probably recharged prior to the Holocene (before 10 ka). The waters apparently ascended to oil-reservoir elevations after deep heating in response to the normal regional thermal gradient; there is no evidence for a modern magmatic heat source. The beginning of oil-reservoir evolution at both fields is recorded by late-stage, fracture-filling quartz in the vuggy, brecciated, Paleozoic dolostone reservoir rocks. Oil and aqueous solutions were trapped as fluid inclusions in the quartz at temperatures comparable to those now prevailing in the reservoirs. Present day and fluid-inclusion temperatures define essentially coincident isothermal profiles through and beneath the oil-reservoir interval, a phenomenon consistent with near-constant convective heat transfer since inception of the geothermal system. Some basin and range oil fields have arisen as valuable byproducts of actively circulating geothermal systems and blending this concept into current exploration stratigies could hasten discovery of the 100 mbbl fields many geologists believe remain to be found in this region. 100 refs., 13 figs., 5 tabs.

  19. The shallow seismic structure of the Larderello geothermal field (Italy) as seen from Receiver Function analysis

    NASA Astrophysics Data System (ADS)

    Piana Agostinetti, Nicola; Licciardi, Andrea; Piccinini, Davide; Mazzarini, Francesco; Musumeci, Giovanni; Saccorotti, Gilberto

    2017-04-01

    The Larderello field (Tuscany, Italy) is the oldest example in the world of geothermal energy exploitation for industrial purposes. Despite its century long history of exploration and exploitation, the deep structure (4-8km depth) of the Larderello field is still poorly known, due to (a) the lack of resolution of the applied exploration techniques and (b) the lack of interest in the investigation of deep geothermal reservoirs, given the abundant amount of energy extracted from the shallow reservoirs. Recently, the increasing demand of green-energy promoted a renewed interest in the geothermal industrial sector, which translated into new exploration efforts, especially to obtain a detailed characterization of deep geothermal sources. We investigate the seismic structure of the Larderello geothermal field using Receiver Function (RF) analysis. Crustal seismic structures are routinely investigated using the RF methodology, where teleseismic P-wave are analysed to extract P-to-S converted phases that can be related to the propagation of the P-wave across a seismic discontinuity. We compute RF from 26 seismic stations, belonging to both temporary and permanent networks: the GAPSS and RETREAT experiments and the Italian Seismic Network. The RF data-set is migrated at depth and decomposed into azimuthal harmonics. Computing the first, k=0, and the second, k=1, harmonics allows to separate the "isotropic" contribution, due to the change of the isotropic properties of the sampled materials (recorded on the k=0 harmonics), from the "anisotropic" contribution, where the energy is related to the propagation of the P-wave through anisotropic materials (recorded on the k=1 harmonics). Preliminary results allow us: (1) to infer the position of the main S-wave velocity discontinuities in the study area, mainly a shallow Tyrrhenian Moho and a very-low S-wave velocity body in the center of the Larderello dome, at about 5-15km depth; and (2) to map the presence of anisotropic

  20. Spectral reflectance analysis of hydrothermal alteration in drill chips from two geothermal fields, Nevada

    NASA Astrophysics Data System (ADS)

    Lamb, A. K.; Calvin, W. M.

    2010-12-01

    We surveyed drill chips with a lab spectrometer in the visible-near infrared (VNIR) and short-wave infrared (SWIR) regions, 0.35-2.5 μm, to evaluate hydrothermal alteration mineralogy of samples from two known geothermal fields in western Nevada. Rock is fractured into small pieces or “chips” during drilling and stored in trays by depth interval. The drill chips are used to determine subsurface properties such as lithology, structure, and alteration. Accurately determining alteration mineralogy in the geothermal reservoir is important for indicating thermal fluids (usually associated with fluid pathways such as faults) and the highest temperature of alteration. Hydrothermal minerals, including carbonates, iron oxides, hydroxides, sheet silicates, and sulfates, are especially diagnostic in the VNIR-SWIR region.. The strength of reflectance spectroscopy is that it is rapid and accurate for differentiating temperature-sensitive minerals that are not visually unique. We examined drill chips from two western Nevada geothermal fields: Hawthorne (two wells) and Steamboat Springs (three wells) using an ASD lab spectrometer with very high resolution. The Steamboat Hills geothermal field has produced electricity since 1988 and is well studied, and is believed to be a combination of extensional tectonics and magmatic origin. Bedrocks are Cretaceous granodiorite intruding into older metasediments. Hot springs and other surface expressions occur over an area of about 2.6 km2. In contrast, the Hawthorne geothermal reservoir is a ‘blind’ system with no surface expressions such as hot springs or geysers. The geothermal field is situated in a range front fault zone in an extensional area, and is contained in Mesozoic mixed granite and meta-volcanics. We collected spectra at each interval in the chip trays. Interval length varied between 10’ and 30’. - Endmember analysis and mineral identification were performed -using standard analysis approaches used to map mineralogy

  1. Identification of linear features at geothermal field based on Segment Tracing Algorithm (STA) of the ALOS PALSAR data

    NASA Astrophysics Data System (ADS)

    Haeruddin; Saepuloh, A.; Heriawan, M. N.; Kubo, T.

    2016-09-01

    Indonesia has about 40% of geothermal energy resources in the world. An area with the potential geothermal energy in Indonesia is Wayang Windu located at West Java Province. The comprehensive understanding about the geothermal system in this area is indispensable for continuing the development. A geothermal system generally associated with joints or fractures and served as the paths for the geothermal fluid migrating to the surface. The fluid paths are identified by the existence of surface manifestations such as fumaroles, solfatara and the presence of alteration minerals. Therefore the analyses of the liner features to geological structures are crucial for identifying geothermal potential. Fractures or joints in the form of geological structures are associated with the linear features in the satellite images. The Segment Tracing Algorithm (STA) was used for the basis to determine the linear features. In this study, we used satellite images of ALOS PALSAR in Ascending and Descending orbit modes. The linear features obtained by satellite images could be validated by field observations. Based on the application of STA to the ALOS PALSAR data, the general direction of extracted linear features were detected in WNW-ESE, NNE-SSW and NNW-SSE. The directions are consistent with the general direction of faults system in the field. The linear features extracted from ALOS PALSAR data based on STA were very useful to identify the fractured zones at geothermal field.

  2. Consideration of geological aspects and geochemical parameters of fluids in Bushdi geothermal field, south of mount Sabalan, NW Iran

    NASA Astrophysics Data System (ADS)

    Masoumi, Rahim; Calagari, Ali Asghar; Siahcheshm, Kamal; Porkhial, Soheil; Pichler, Thomas

    2017-05-01

    The geothermal field at Bushdi to the south of Sabalan volcano encompasses both cold and hot springs along with surficial steam vents. This geothermal field is situated in a volcanic terrain which includes basaltic and trachy-andesitic lavas and pyroclastics which have undergone considerable faulting during Quaternary times. Regardless of conventional uses, no industrial utilization has been reported from this field yet. In the geothermal fluids Na is the most abundant cation following the trend Na+ >> Ca2+ > K+ > Mg2+. Cl- is the most abundant anion following two trends (1) Cl- >> HCO3- > SO42- and (2) HCO3- > Cl- > SO42-. From a hydrogeochemical point of view the geothermal fluids in the study area can be divided into two categories: (1) Na-Cl and (2) Na-Ca-HCO3. The conic and lenticular shaped travertine deposits around hot springs possessing a Ca2+-Na+-HCO3- composition are the most conspicuous features in this area. According to oxygen and hydrogen stable isotopes (δD and δ18O) data, a large proportion of the fluids in this geothermal system are of meteoric origin. Downward percolation along the brecciated rocks in the fault zones between the mount Sabalan and the Bushdi area can be regarded as the main fluid source for the geothermal system. The geothermal fluids have 3H above 1 TU and hence can be considered as young (modern to sub-modern) waters, with a residence time of less than 63 years.

  3. Fluid inclusions in minerals from the geothermal fields of Tuscany, Italy

    USGS Publications Warehouse

    Belkin, H.; de Vivo, B.; Gianelli, G.; Lattanzi, P.

    1985-01-01

    A reconnaissance study on fluid inclusions from the geothermal fields of Tuscany indicates that the hydrothermal minerals were formed by fluids which were, at least in part, boiling. Four types of aqueous inclusions were recognized: (A) two-phase (liquid + vapor) liquid rich, (B) two-phase (vapor + liquid) vapor rich, (C) polyphase hypersaline liquid rich and (D) three phase-H2O liquid + CO2 liquid + CO2-rich vapor. Freezing and heating microthermometric determinations are reported for 230 inclusions from samples from six wells. It is suggested that boiling of an originally homogeneous, moderately saline, CO2-bearing liquid phase produced a residual hypersaline brine and a CO2-rich vapor phase. There are indications of a temperature decrease in the geothermal field of Larderello, especially in its peripheral zones. ?? 1985.

  4. 3-D seismic velocity and attenuation structures in the geothermal field

    SciTech Connect

    Nugraha, Andri Dian; Syahputra, Ahmad; Fatkhan,; Sule, Rachmat

    2013-09-09

    We conducted delay time tomography to determine 3-D seismic velocity structures (Vp, Vs, and Vp/Vs ratio) using micro-seismic events in the geothermal field. The P-and S-wave arrival times of these micro-seismic events have been used as input for the tomographic inversion. Our preliminary seismic velocity results show that the subsurface condition of geothermal field can be fairly delineated the characteristic of reservoir. We then extended our understanding of the subsurface physical properties through determining of attenuation structures (Qp, Qs, and Qs/Qp ratio) using micro-seismic waveform. We combined seismic velocities and attenuation structures to get much better interpretation of the reservoir characteristic. Our preliminary attanuation structures results show reservoir characterization can be more clearly by using the 3-D attenuation model of Qp, Qs, and Qs/Qp ratio combined with 3-D seismic velocity model of Vp, Vs, and Vp/Vs ratio.

  5. Field trip guide to the Valles Caldera and its geothermal systems

    SciTech Connect

    Goff, F.E.; Bolivar, S.L.

    1983-12-01

    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.

  6. Simulation of the Heber geothermal field, a TOUGH2/PC application

    SciTech Connect

    Antunez, E.; Lippmann, M.; Ali Khan, M.

    1995-03-01

    A numerical simulation model for the Heber geothermal field in southern California is being developed under a technology transfer agreement between the Department of Energy/LBL and the California Department of Conservation, Division of Oil, Gas, and Geothermal Resources (Division). The two objectives of the cooperation are: (1) to train Division personnel in the use of the TOUGH2/PC computer code; and (2) to develop a module compatible with TOUGH2 to investigate the effects of production/injection operations on the ground surface subsidence-rebound phenomenon observed in the field. The compaction of the rock formation will be handled assuming an elastic behavior of the rock-fluid system. Considered will be changes in pore volume and in-grid block dimensions, as well as, the process by which the change in formation volume is transmitted to the surface (vertical deformation; subsidence and rebound).

  7. Field tests of 2- and 40-tube condensers at the East Mesa Geothermal Test Site

    SciTech Connect

    Murphy, R.W.; Domingo, N.

    1982-05-01

    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.

  8. Slope stability analysis of landslide in Wayang Windu Geothermal Field, Pangalengan, West Java Province, Indonesia

    NASA Astrophysics Data System (ADS)

    Yuhendar, A. H.; Wusqa, U.; Kartiko, R. D.; Raya, N. R.; Misbahudin

    2016-05-01

    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.

  9. A summary of modeling studies of the Nesjavellir geothermal field, Iceland

    SciTech Connect

    Bodvarsson, G.S.; Bjornsson, S.; Gunnarsson, A.; Gunnlaugsson, E.; Sigurdsson,, O. Stefansson, V.; Steingrimsson, B.

    1988-01-01

    The Nesjavellir geothermal field in Iceland is being developed to provide the capital city of Reykjavik and surrounding areas with hot water for space heating. In the last few years, many wells have been drilled at the site and various geothermal studies have been conducted. The main upflow to the system is underneath the nearby Hengill volcano, and the natural recharge rate and enthalpy are estimated to be 65 kg/s and 1850 kJ/kg, respectively. An extensive vapor zone is believed to be present in the upflow region. Permeabilities and porosities of the system range between 1 and 50 md and 1 and 10 percent, respectively. In this paper, the characteristics of the Nesjavellir field are described and a three-dimensional numerical model of the resource in discussed. 15 refs., 11 figs., 1 tab.

  10. Ultrasonic measurements at in-situ conditions in a geothermal field: Ngatamariki field, New Zealand.

    NASA Astrophysics Data System (ADS)

    Durán, E.; Adam, L.; Wallis, I. C.

    2016-12-01

    A set volcaniclastic and pyroclastic rocks were collected from Ngatamariki Geothermal Field. Two sets of measurements were carried out in core samples from geological intervals used for injection. The first set of measurements were made at surface conditions using ultrasonic transducers. The second measurements were made simulating in-situ confining and fluid pressures of the field inside a pressure vessel. A comparison of both approaches is made in order to validate existing data and expand the geophysical information collected in the field. Previous work on the rocks has shown that there is large variation in the physical and mechanical properties with depth, which might indicate that effects of lithology and hydrothermal alteration are controlling factors in the observed variability, nevertheless the addition of fluid pressures has never been studied in these rocks. Both datasets have been used to improve the identification and interpretation of P and S-wave arrivals and understand their variation with pressure and fluid content. Previous laboratory results on mineralogy, clay content, porosity, permeability, crack density and orientation are incorporated into the analysis. Finally, a methodology is presented to aid in the calibration and interpretation of S-wave arrivals for the transducers built to perform the experiments at in-situ conditions. Since the compressional and shear piezoelectric crystals used are packed in a single casing, converted waves must be identified on top of the direct arrivals. By comparing the source signature of the measurements performed on the bench to the waveforms recorded at field conditions, we aid the eye interpretation of picked times by adapting a Dynamic Time Warping algorithm for the task.

  11. Matched Filter Detection of Microseismicity at Ngatamariki and Rotokawa Geothermal Fields, Central North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Hopp, C. J.; Savage, M. K.; Townend, J.; Sherburn, S.

    2016-12-01

    Monitoring patterns in local microseismicity gives clues to the existence and location of subsurface structures. In the context of a geothermal reservoir, subsurface structures often indicate areas of high permeability and are vitally important in understanding fluid flow within the geothermal resource. Detecting and locating microseismic events within an area of power generation, however, is often challenging due to high levels of noise associated with nearby power plant infrastructure. In this situation, matched filter detection improves drastically upon standard earthquake detection techniques, specifically when events are likely induced by fluid injection and are therefore near-repeating. Using an earthquake catalog of 637 events which occurred between 1 January and 18 November 2015 as our initial dataset, we implemented a matched filtering routine for the Mighty River Power (MRP) geothermal fields at Rotokawa and Ngatamariki, central North Island, New Zealand. We detected nearly 21,000 additional events across both geothermal fields, a roughly 30-fold increase from the original catalog. On average, each of the 637 template events detected 45 additional events throughout the study period, with a maximum number of additional detections for a single template of 359. Cumulative detection rates for all template events, in general, do not mimic large scale changes in injection rates within the fields, however we do see indications of an increase in detection rate associated with power plant shutdown at Ngatamariki. Locations of detected events follow established patterns of historic seismicity at both Ngatamariki and Rotokawa. One large cluster of events persists in the southeastern portion of Rotokawa and is likely bounded to the northwest by a known fault dividing the injection and production sections of the field. Two distinct clusters of microseismicity occur in the North and South of Ngatamariki, the latter appearing to coincide with a structure dividing the

  12. Interpretation of interference effects in three production wells in the Kawerau geothermal field, New Zealand

    SciTech Connect

    Stevens, Lynell; Koorey, Kevin J.

    1996-01-24

    Downhole temperature and pressure, mass flow, and enthalpy measurements on three production wells at Kawerau geothermal field are interpretted to illustrate interference effects between these wells. Feed zone locations within the wells, together with geology and chemistry are discussed. Downhole measurements are made in one well while production flow changes are made on another well to monitor pressure transient effects. The interference effects have implications for planning future production drilling.

  13. Decline curve analysis of production data from The Geysers geothermal field

    SciTech Connect

    Ripperda, M.; Bodvarsson, G.S.

    1987-01-01

    Production data for over two hundred wells at The Geysers geothermal field were compiled and analyzed. Decline curves for groups of wells with 5, 10, and 40 acre spacing are presented and compared to curves published previously by Budd (1972) and Dykstra (1981). Decline curves for several individual wells and leases are discussed to illustrate the effects of well spacing and location, as well as the heterogeneous nature of the reservoir.

  14. Decline Curve Analysis of Production Data from the Geysers Geothermal Field

    SciTech Connect

    Ripperda, M.; Bodvarsson, G.S.

    1987-01-20

    Production data for over two hundred wells at The Geysers geothermal field were compiled and analysed. Decline curves for groups of wells with 5, 10, and 40 acre spacing are presented and compared to curves published previously by Budd (1972) and Dykstra (1981). Decline curves for several individual wells and leases are discussed to illustrate the effects of well spacing and location, as well as the heterogeneous nature of the reservoir. 6 figs., 1 tab., 10 refs.

  15. Hydrology and Model of the Okoy Geothermal Field, Negros Oriental, Republic of the Philippines

    SciTech Connect

    Smith, E.W.

    1980-12-16

    Ward (1980) described the exploration of the Okoy geothermal field. Resistivity surveying using Schlumberger traverses has covered an area of approximately 800 km2 in the southern part of the Island of Negros. Hot springs and other thermal manifestations occur in the Okoy valley, Valencia and at Tabac Magaso, Dauin. Initial shallow exploratory drilling indicated a possible sub-surface flow of hot water in the Okoy valley. Further deep exploratory drilling to the West has located two high temperature reservoirs.

  16. Reflection seismic imaging in the volcanic area of the geothermal field Wayang Windu, Indonesia

    NASA Astrophysics Data System (ADS)

    Polom, Ulrich; Wiyono, Wiyono; Pramono, Bambang; Krawczyk, CharLotte M.

    2014-05-01

    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

  17. Microearthquake Study of the Salton Sea Geothermal Field, California: Evidence of Stress Triggering - Masters Thesis

    SciTech Connect

    Holland, Austin Adams

    2002-02-01

    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.

  18. Geodetic Measurements and Numerical Models of Deformation at Coso Geothermal Field, California, USA

    NASA Astrophysics Data System (ADS)

    Ali, S. T.; Reinisch, E. C.; Feigl, K. L.; Davatzes, N. C.

    2016-12-01

    We measure transient deformation at the Coso geothermal field in south-central California using interferometric synthetic aperture data acquired between 2004 and 2016 by the Envisat and Sentinel-1A satellite missions. All well-correlated interferometric pairs show subsidence, with rates as high as 30 mm/year, over a large 75 km2 circular area surrounding the field below which most of the seismicity associated with geothermal production is located. The deformation signature remains in the same location throughout the 12 year interval. Time-series analysis of multiple interferometric pairs reveals continuous subsidence. A decrease in the subsidence rate after 2010 corresponds to a decrease in the net production rate. Using three-dimensional, fully numerical, multiphysics models, we explore the coupling between deformation and geothermal production. We seek to distinguish between two possible mechanisms: (i) decreasing pore-pressure following net extraction of fluids, or (ii) decrease in temperature of presumably fractured reservoir rock. Irrespective of the mechanism, a contracting ellipsoidal reservoir located at a depth of 2 km, with a volume of 80 km3 or less is required to explain the geodetic observations. Almost 90% of the seismicity beneath the field occurs within this 80 km3 ellipsoid.

  19. Temporal changes in shear velocity from ambient noise at New Zealand geothermal fields

    NASA Astrophysics Data System (ADS)

    Civilini, F.; Savage, M. K.; Townend, J.

    2016-12-01

    We use ambient noise to compare shear velocity changes with geothermal production processes at the Ngatamariki and Rotokawa geothermal fields, located in the central North Island of New Zealand. We calculate shear velocity changes through an analysis of cross correlation functions of diffusive seismic wavefields between stations, which are proportional to Green's functions of the station path. Electricity production at Ngatamariki uses an 82 MW binary type power station manufactured by Ormat Technologies, which began operations in mid-2013 and is owned and operated by Mighty River Power. The "Nga Awa Purua" triple flash power plant at the Rotokawa geothermal field was established in 2010 with parnership between Mighty River Power and Tauhara North No. 2 trust and currently operates 174 MW of generation. The seismometers of both networks, deployed primarily to observe microseismicity within the field, were installed prior to well stimulation and the start of production. Although cultural noise dominates the energy spectrum, a strong natural ambient noise signal can be detected when filtering below 1 Hz. Despite similar noise settings, the signal-to-noise ratio of cross correlation stacks at Rotokawa was more than two times greater than at Ngatamariki. We use stacks of cross correlations between stations prior to the onset of production as references, and compare them with cross correlations of moving stacks in time periods of well stimulation and the onset of electricity production.

  20. Small biphase wellhead plant for the Cerro Prieto Mexico geothermal field

    SciTech Connect

    Oropeza, A.; Hays, L.

    1996-12-31

    In a system of geothermal wells in a geothermal field, there are different production conditions of the flows, temperatures and pressures. At plants where the installed capacity requires the use of many wells, it is necessary to regulate the well`s pressure to ensure a stable condition for the turbines. Reducing the steam pressure on the wellhead is achieved by using an orifice plate (flash orifice). Use of an orifice plate results in a waste or loss of well pressure that could be utilized for production of electricity. The Cerro Prieto field, operated by the Comision Federal de Electricidad (CFE), has many wells operating at a very high pressure and producing a lot of water. Much of this pressure and water is not utilized in the production of electricity. With the purpose of taking advantage of this pressure CFE has evaluated a proposal by Biphase Energy Co. Biphase has designed and patented a turbine that works directly with the steam and water mixture coming from the wellhead, acting as a separator. Biphase has developed a model of its turbine and successfully operated it in Coso Hot Springs California. Knowing this CFE has signed an agreement with Biphase Energy Company to install and operate a biphasic turbine at the Cerro Prieto geothermal field located near Mexicali, Mexico.

  1. Solar Field Optical Characterization at Stillwater Geothermal/Solar Hybrid Plant

    DOE PAGES

    Zhu, Guangdong; Turchi, Craig

    2017-01-27

    Concentrating solar power (CSP) can provide additional thermal energy to boost geothermal plant power generation. For a newly constructed solar field at a geothermal power plant site, it is critical to properly characterize its performance so that the prediction of thermal power generation can be derived to develop an optimum operating strategy for a hybrid system. In the past, laboratory characterization of a solar collector has often extended into the solar field performance model and has been used to predict the actual solar field performance, disregarding realistic impacting factors. In this work, an extensive measurement on mirror slope error andmore » receiver position error has been performed in the field by using the optical characterization tool called Distant Observer (DO). Combining a solar reflectance sampling procedure, a newly developed solar characterization program called FirstOPTIC and public software for annual performance modeling called System Advisor Model (SAM), a comprehensive solar field optical characterization has been conducted, thus allowing for an informed prediction of solar field annual performance. The paper illustrates this detailed solar field optical characterization procedure and demonstrates how the results help to quantify an appropriate tracking-correction strategy to improve solar field performance. In particular, it is found that an appropriate tracking-offset algorithm can improve the solar field performance by about 15%. The work here provides a valuable reference for the growing CSP industry.« less

  2. Three-dimensional Magnetotelluric Characterization of the Xinzhou Geothermal Field, Southeastern China

    NASA Astrophysics Data System (ADS)

    Han, Q.; Hu, X.; Cai, J.; Wei, W.

    2016-12-01

    Xinzhou geothermal field is located in the Guangdong province and adjacent to the China South Sea, and its hot springs can reach up to 92 degree Celsius. Yanshanian granite expose widely in the south of this geothermal field and four faults cut across each other over it. A dense grid of 176 magnetotelluric (MT) sites with broadband has been acquired over the Xinzhou geothermal field and its surrounding area. Due to the related electromagnetic (EM) noise one permanent observatory was placed as a remote reference to suppress this cultural EM noise interference. The datasets are processed using the mutual reference technique, static shift correction, and structural strike and dimensionality analysis based on tensor decomposition. Data analysis reveals that the underground conductivity structure has obvious three-dimensional characterization. For the high resolution result ,two and three dimensional inversion are both applied in this area employing the non-linear conjugate gradient method (NLCG).These MT data sets are supposed to detect the deep subsurface resistivity structure correlated to the distribution of geothermal reservoir (such as faults and fractured granite) and investigate the channel of the upwelling magma. The whole and cold granite usually present high resistivity but once it functions as reservoir the resistivity will decrease, sometimes it is hard to separate the reservoir from the cap layer. The 3D inversion results delineate three high resistivity anomalies distributed in different locations. At last we put forward that the large areas of granite form the major thermal source for the study area and discuss whether any melt under these magma intrusions exists.

  3. Open questions on the origin of life at anoxic geothermal fields.

    PubMed

    Mulkidjanian, Armen Y; Bychkov, Andrew Yu; Dibrova, Daria V; Galperin, Michael Y; Koonin, Eugene V

    2012-10-01

    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.

  4. Steam and Brine Zone Prediction around Geothermal Reservoir Derived from Delay Time Seismic Tomography and Anisotropy Case Study: “PR” Geothermal Field

    NASA Astrophysics Data System (ADS)

    Hendrawan Palgunadi, Kadek; Nugraha, A. D.; Sule, R.; Meidiana, T.

    2017-04-01

    Development of geothermal production can be conducted in several ways, one of them analyses the fracture or crack and structure within the reservoir. Due to low permeability and porosity value within the reservoir in geothermal field. This crack or fracture provide porosity for fluid storage and permeability for fluid movement and play a major role in production from this kind of reservoir. Structure and polarization direction can be derived from anisotropy parameter and seismic velocity parameter in geothermal field. In this study, we used micro-earthquake data of 1,067 events that were recorded by the average of 15 stations during almost 1-year measurement. We used anisotropy parameter using 3-D shear-wave splitting (SWS) tomography method to represent the distribution of anisotropy medium around the geothermal field. Two parameters produced from the S-wave analysis, which is polarization direction and delay time between fast S-wave and slow S-wave. To determine SWS parameters, we used a rotation of horizontal seismogram including N-S component and E-W component. Furthermore, we used short-time fourier transform (STFT) to calculate lag time and time window based on wave periods. Two horizontal components have been rotated from azimuth 0° to 180° with an increment of 1°. Cross-correlation coefficient used every azimuth of two horizontal components based on delay time with predetermined time window obtained by STFT. When cross-correlation coefficient is high, the corresponding value of delay time and azimuth are chosen as the polarization direction and delay time of SWS. Normalized time different divided by total ray length was used to determine the distribution of crack density. Through correlation of seismic velocity model, crack density, and 3-D anisotropy tomography, we can delineate a geothermal reservoir model. Our results show, high degree of anisotropy and crack density occur in the northern and eastern part of “PR” geothermal field for further

  5. A joint geophysical analysis of the Coso geothermal field, south-eastern California

    NASA Astrophysics Data System (ADS)

    Wamalwa, Antony M.; Mickus, Kevin L.; Serpa, Laura F.; Doser, Diane I.

    2013-01-01

    Three-dimensional density models derived from gravity data and two-dimensional resistivity models derived from magnetotelluric data collected in the vicinity of the Coso geothermal field are analyzed in order to determine the source region of the geothermal field. The derived models show zones of both low resistivity and low density at and below 6 km depth in the Devils Kitchen and the Coso Hot Springs areas. These zones agree with seismic reflection and tomography results which found a high amplitude reflector at 5 km and low velocities zones below 5 km. We interpret the density and resistivity zones to indicate the presence of cooling magmatic material that provides the heat for the shallower geothermal system in these regions. A zone marked by high resistivity and low density was found to lie directly above the interpreted partially melted region extending to within 1 km depth below the surface in the reservoir region where it is capped by a low resistivity clay zone. In addition, the density models indicate that the high density bodies occurring under volcanic outcrops may be mafic intrusions.

  6. Durability of various cements in a well of the Cerro Prieto geothermal field

    SciTech Connect

    Krause, Ralph F., Jr.; Kukacka, Larry E.

    1982-10-08

    The durability of each of 16 different cements was evaluated by both room temperature compressive strength and water permeability measurements, following various periods of treatment of the cements in flowing geothermal fluid of the Cerro Prieto field of Mexico. Some of these cements were selected through a Department of Energy program to develop improved cements for geothermal well completion while the others were contributed by several other institutions interested in the tests. Two types of specimens of the cements were used in the tests: (a) 50 mm cubes which were precured 1 da in molds under water in an autoclave at 200 C and 20 MPa and (b) cement slurries which were prepared and cast in sandstone cups at the field. Federal de Electricidad a set of both types of specimens was installed in baskets which were placed 700 m downhole a well at 214 C, and an identical set of specimens was installed in special aboveground vessels near the wellhead. Following periods of 1 da. 3 mo, 6 mo. and 12 mo, specimens were withdrawn from the geothermal treatment and divided evenly between the Instituto de Investigaciones Electricas and the National Bureau of Standards for property measurements. This paper gives the downhole results by the latter laboratory. Final values will be published when the results of both laboratories are collated and reviewed.

  7. Regional hydrology of the Dixie Valley geothermal field, Nevada: preliminary interpretations of chemical and isotopic data

    SciTech Connect

    Counce, D; Dunlap, C; Goff, F; Huebner, M; Janik, C; Johnson, S; Nimz, G

    1999-08-16

    Chemical and isotopic analyses of Dixie Valley regional waters indicate several distinct groups ranging in recharge age from Pleistocene (<20 ka) to recent (<50a). Valley groundwater is older than water from perennial springs and artesian wells in adjacent ranges, with Clan Alpine range (east) much younger (most <50a) than Stillwater range (west; most >1000a). Geothermal field fluids ({approximately}12-14 ka) appear derived from water similar in composition to non-thermal groundwater observed today in valley artesian wells (also -14 ka). Geothermal fluid interaction with mafic rocks (Humboldt Lopolith) appears to be common, and significant reaction with granodiorite may also occur. Despite widespread occurrence of carbonate rocks, large scale chemical interaction appears minor. Age asymmetry of the ranges, more extensive interaction with deep-seated waters in the west, and distribution of springs and artesian wells suggest the existence of a regional upward hydrologic gradient with an axis in proximity to the Stillwater range.

  8. Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field

    SciTech Connect

    Valette-Silver, J.N.; Esquer P., I.; Elders, W.A.; Collier, P.C.; Hoagland, J.R.

    1981-01-01

    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.

  9. Regional hydrology of the Dixie Valley geothermal field, Nevada: preliminary interpretations of chemical and isotopic data

    USGS Publications Warehouse

    Nimz, Gregory; Janik, Cathy; Goff, Fraser; Dunlap, Charles; Huebner, Mark; Counce, Dale; Johnson, Stuart D.

    1999-01-01

    Chemical and isotopic analyses of Dixie Valley regional waters indicated several distinct groups ranging in recharge age from Pleistocene (1000a). Geothermal field fluids (~12-14 ka) appear derived from water similar in composition to non thermal groundwater observed today in valley artesian well (also ~14 ka). Geothermal fluid interaction with mafic rocks (Humboldt Lopolith) appears to be common, and significant reaction with granodiorite may also occur. Despite widespread occurrence of carbonate rocks, large scale chemical interaction appears minor. Age asymmetry of the range, more extensive interaction with deep seated waters in the west, and distribution of springs and artesian wells suggest the existence of a regional upward hydrologic gradient with an axis in proximity to the Stillwater range.

  10. Sustainable development of geothermal fields in the Pannonian Basin - A case study

    SciTech Connect

    Panu, Dumitru; Mitrofan, Horia; Serbu, Viorel

    1996-01-24

    As suggested by the discusssion of Barker, 1988, on the influence of flow dimension on the late-time behaviour of the generalized line source solution, it was inferred that observed long term reservoir pressure decline was an outcome of the 1D (linear) flow geometry, indicated by well tests. The detrimental effects of the reservoir pressure decline can be partly mitigated by taking advantage of the two-phase flow which occurs when methane, originally dissolved in the geothermal brine, is released within the well bore. Sustainable artesiar withdrawal scenarios for existing geothermal fields are devised, based on an accurate prediction of bottomhole pressure decline trends and an adequate selection of the diameter and length of the production tubing. Overall analysis and forecast are performed by an integrated reservoir & well bore simulator.

  11. Hydrothermal characteristics of the well A-29 at the Los Azufres geothermal field, Mexico

    SciTech Connect

    Viggiano-Guerra, J.C.; Gutierrez-Negrin, L.C.A.

    1995-12-31

    Three distinct hydrothermal zones can be identified in the well A-29, located at the northeastern border of the Los Azufres, Mexico, geothermal field. They are the zeolite, epidote and amphibole-gamet zones. High temperatures (over 300{degrees}C) were measured, but the well did not produce mass flow. This can be explained by a self-sealing process as a result of three trends recognized in the evolution of geothermal fluids: boiling, boiling and gas losses, and dilution. A certain cooling of at least 25{degrees}C seems to be happening in the well, especially in the epidote zone and in the upper portions of the amphibole-gamet zone.

  12. Porosity of coastal deltaic sandstones, Cerro Prieto geothermal field, Baja California, Mexico

    SciTech Connect

    Vonder Haar, S.P.

    1984-04-01

    Core porosity values for sandstones and density log-derived porosities for sandstone-siltstone-shale sequences indicate a range from less than 1% to 40% at the Cerro Prieto geothermal field, Baja California, Mexico. Mean porosity values indicate that a general trend of decreasing porosities with increasing depth from 35% at 600 m to 10% at 2300 m is complicated by the 15 to 30% porosities in the 350/sup 0/C hot water zone at about 2700 m depth. Scanning electron microscopy documents secondary dissolution porosity, mineral overgrowths, and abundant clay minerals. Core permeability ranges from 0.1 to 1000 millidarcies for the more than 50 cores studied. The porosity variability indicates that geothermal systems provide an ideal setting for testing concepts of dissolution porosity and increased secondary dissolution permeability that could be useful for nuclear waste storage as well as petroleum reservoir engineering.

  13. Mercury in freshwater fish and clams from the Cerro Prieto geothermal field of Baja California, Mexico

    SciTech Connect

    Gutierrez-Galindo, E.A.; Munoz, G.F.; Flores, A.A.

    1988-08-01

    Several reports have expressed concern about the potential toxicity hazards and environmental contamination of mercury emissions from geothermal fields in Hawaii, New Zealand, Iceland, California and Mexico. Inorganic mercury discharged from the sources may accumulate in the sediments of rivers or lakes and, after microbiological methylation may become concentrated in the edible tissue of fish. This study involves assessment of geothermal mercury pollution arising from Cerro Prieto. For this purpose the fish Tilapia mossambica and the clam Corbicula fluminea were collected from the freshwater courses of the Mexicali Valley. Reports indicated that in 1982, 13 t of T. mossambica were destinated for human consumption. A further aim was to provide base line data and information relevant to the level of mercury contamination for the Mexicali Valley.

  14. Gas Geothermometry Based on CO Content--Application in Italian Geothermal Fields

    SciTech Connect

    D'Amore, F.; Fancelli, R.; Saracco, L.; Truesdell, A.H.

    1987-01-20

    This paper discusses gas chemical equilibria in geothermal reservoirs involving the species CO{sub 2}, CH{sub 4}, CO, H{sub 2}S, H{sub 2}, and H{sub 2}O. A set of equations is developed correlating ratios of gas to CO{sub 2} with temperature, steam fraction, and CO{sub 2} partial pressure in the reservoir. A method for solving the set of nonlinear equations is proposed. These equations do not involve discharge gas/total H{sub 2}O ratios and may therefore be used for fumaroles and hot-spring fluids. Applications to fumarole and well-discharge fluid compositions in Italian geothermal fields show good correlations between temperatures calculated with this method and the temperatures measured in the reservoir (between 140° to 330°C). 5 tabs., 1 fig., 19 refs.

  15. Fluid flow in the Rotorua geothermal field derived from isotopic and chemical data

    SciTech Connect

    Stewart, M.K.; Lyon, G.L.; Robinson, B.W. ); Glover, R.B. )

    1992-04-01

    A wide variety of isotopic and chemical measurements on geothermal fluids from shallow wells at Rotorua have given the following interpretations: The Rotorua field comprises one geothermal system; a primary upflow of (outgassed) alkali chloride water extends from northeast Whakarewarewa to Ngapuna and under Lake Rotorua (east side of the system). At the southern end a secondary upflow discharges dilute alkali chloride water; a second major upflow at Kuirau-Ohinmutu discharges chloride-bicarbonate waters formed by dilution of the primary water and reaction with rock; boiling primary water flows from the eastern upflow zone under confining sediments into aquifers in Rotorua Rhyolite containing chloride-bicarbonate waters in the central region; tritium-bearing groundwater penetrates from overlying aquifers in the sediment into the saddle area between the rhyolite domes or along the crest of the southern rhyolite dome and flows northeast into the northern dome.

  16. Geology Structure Identification based on Polarimetric SAR (PolSAR) Data and Field Based Observation at Ciwidey Geothermal Field

    NASA Astrophysics Data System (ADS)

    Pradipta, R. A.; Saepuloh, A.; Suryantini

    2016-09-01

    Geological structure observation is difficult to be conducted at Quaternary volcanic field due to the classical problem at tropical region such as intensive erosion, dense vegetation covers, and rough terrain. The problem hampers the field observation especially for geological structures mapping. In order to overcome the problems, an active remote sensing technology based on Polarimetric Synthetic Aperture Radar (PolSAR) data was used in this study. The longer wavelength of microwave than optical region caused the SAR layer penetration higher than optics. The Ciwidey Geothermal Field, Indonesia was selected as study area because of the existence of surface manifestations with lack information about the control of geological structures to the geothermal system. Visual interpretation based on composite polarization modes was applied to identify geological structures at study area. The color composite Red-Green-Blue for HV-HH-VV polarizations provided highest texture and structural features among the other composite combination. The Linear Features Density (LFD) map was also used to interpret the fractures zones. The calculated LFD showed high anomaly about 3.6 km/km2 with two strike directions NW-SE and NE-SW. Interestingly, the surface geothermal manifestation agreed with the low anomaly of LFD. The geological structures consisted of ten faults were successfully detected and mapped. The faults type mainly are oblique-slip with strike directions NE-SW and NW-SE.

  17. Reservoir Characterization around Geothermal Field, West Java, Indonesia Derived from 4-D Seismic Tomography

    NASA Astrophysics Data System (ADS)

    Verdhora Ry, Rexha; Nugraha, A. D.

    2016-01-01

    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.

  18. Origin of rainwater acidity near the Los Azufres geothermal field, Mexico

    USGS Publications Warehouse

    Verma, M.P.; Quijano, J.L.; Johnson, Chad; Gerardo, J.Y.; Arellano, V.

    2000-01-01

    The chemical and isotopic compositions of rainwater were monitored at Los Azufres geothermal field (88 MWe) and its surroundings during May - September 1995, which is the rainy season. Samples were collected from eight sites: three within the field, three in its surroundings and two sufficiently far from the field such that they have no geothermal input. The concentrations of Cl-, SO42- and NO3- were measured in about 350 samples and found to be generally <5 ppm. Chloride concentrations remained constant with time, but sulfate and nitrate concentrations decreased, which suggests a nearby industrial source for the sulfate and nitrate. A mixing model for Cl-, SO42- and ??34S also suggests an industrial source for the rainwater sulfur. The determination of pH was found to be necessary, but is not sufficient to characterize rainwater acidity. The Gran titration method was used to determine alkalinity with respect to equivalence point of H2CO3(*). Values of alkalinity were found to range from 10-4 to 10-6 eq/L, and were negative only for some samples from Vivero and Guadalajara. Thus, SO42- and NO3- are in general not in acidic form (i.e. balanced by Na+, Ca2+, etc. rather than H+). Sulfate ??34S values were about -1.5??? in Los Azufres and its surroundings, and in Morelia, but differed from the value of -0.2??? for Guadalajara. The ??34S values for H2S from the Los Azufres geothermal wells are in the range -3.4 to 0.0???. The ??34S ranges for the natural and anthropogenic sources for environmental sulfur overlap, making it difficult to differentiate between the contribution of different sources. However, a similarity of values of ??34S at Los Azufres and Morelia (85 km distant) suggest a regional source of sulfate that is not associated with geothermal emissions from Los Azufres. (C) 2000 Published by Elsevier Science Ltd on behalf of CNR.The chemical compositions of rainwater were analyzed at Los Azufres geothermal field in Spain from May-September 1995. The

  19. Seismicity and deformation in the Coso Geothermal field from 2000 to 2012

    NASA Astrophysics Data System (ADS)

    Kaven, J. Ole; Hickman, Stephen H.; Davatzes, Nicholas C.

    2015-04-01

    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

  20. Summary of modeling studies of the East Olkaria geothermal field, Kenya

    SciTech Connect

    Bodvarsson, G.S.; Pruess, K.; Stefansson, V.; Bjornsson, S.; Ojiambo, S.B.

    1985-03-01

    A detailed three-dimensional well-by-well model of the East Olkaria geothermal field in Kenya has been developed. The model matches reasonably well the flow rate and enthalpy data from all wells, as well as the overall pressure decline in the reservoir. The model is used to predict the generating capacity of the field, well decline, enthalpy behavior, the number of make-up wells needed and the effects of injection on well performance and overall reservoir depletion. 26 refs., 10 figs.

  1. Hydrogeochemical investigations in support of well logging operations at the Zunil geothermal field, Guatemala

    SciTech Connect

    Adams, A.; Golf, F.; Trujillo, P.E. Jr.; Counce, D.; Archuleta, J.; Dennis, B. ); Medina, V. . Inst. Nacional de Electrificacion)

    1990-01-01

    A suite of 41 thermal and nonthermal waters in the Zunil-Quetzaltenango region, Guatemala, were collected as part of a well logging operation conducted by the Instituto Nacional de Electrificacion (INDE) and Los Alamos National Laboratory. Both in situ and weirbox samples were collected in the Zunil geothermal field. The various data suggest that the reservoir at Zunil is geochemically inhomogeneous. Stable isotope data suggest recharge to the field comes primarily from the north and east whereas tritium data indicate that the reservoir waters may be 500 to 7500 years old. 14 refs., 4 figs., 3 tabs.

  2. Flow rate decline and pressure transient in the Larderello geothermal field

    SciTech Connect

    Neri, Guiseppe

    1988-01-01

    The production history of most of the Larderello wells, both the older ones and the recent ones, that we have produced at constant pressure, is characterised by a rapid initial decline. In this study such a decline is interpreted as the consequence of an original flow regime of the “depletion” type being followed by a “diffusion” type regime. Such an interpretation, which does prove consistent with the phenomenology of the geothermal field, was suggested by the results of the analyses of the well-closure tests carried out in the North zone of Larderello and in the Travale field.

  3. Internal structure of fault zones in geothermal reservoirs: Examples from palaeogeothermal fields and potential host rocks

    NASA Astrophysics Data System (ADS)

    Leonie Philipp, Sonja; Reyer, Dorothea; Meier, Silke; Bauer, Johanna F.; Afşar, Filiz

    2014-05-01

    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

  4. NEDO'S project on geothermal reservoir engineering -- a reservoir engineering study of the Kirishima field, Japan

    SciTech Connect

    Kitamura, H.; Ishido, T.; Miyazaki, S.; Abe, I.; Nobumoto, R.

    1988-01-01

    In order to promote the development of geothermal energy resources, it is important to understand and (to the extent possible) to alleviate potential risks associated with each proposed development project. Further, it is essential to estimate the generation capacity of the reservoir prior to full-scale commitment so that the power plant design may be intelligently formulated. Starting in 1984, the New Energy Development Organization (NEDO) in Japan undertook a four-year program to develop technical methods for the evaluation of potential geothermal resources and for the prediction of production capacity and the appropriate level of electrical generation to be anticipated. NEDO’s general approach to theoretical reservoir evaluation is described, as is the schedule and progress along the four-year program toward its four main goals: development of reservoir simulators, drilling of observation wells in two model fields (the Sumikawa field in northern Honshu and the Kirishima field in southern Kyushu), well tests in the model fields, and reservoir simulation with natural-state and production calculation for both fields. The remainder of the paper describes some results obtained from the well testing program in the Kirishima field and ongoing studies of it.

  5. Supercritical heat exchanger field test (SHEFT), I. Field performance data on shell-and-tube heat exchangers in geothermal service

    SciTech Connect

    Silvester, L.F.; Beaulaurier, L.O.; Mirk, K.F.; Fulton, R.L.

    1981-06-01

    Field performance data on shell-and-tube heat exchangers in geothermal service are presented. The test data were taken for geothermal brine on the tube side and hydrocarbon on the shell side in counterflow for six primary heat exchangers, and for hydrocarbon on the shell side and cooling water on the tube side for the condenser. Test data were for heating isobutane, 1 90/10 isobutane/isopentane mixture, and a 80/20 isobutane/isopentane mixture at supercritical conditions in the vicinity of their critical pressure and temperature, and for condensing the same fluids. The test data were used in a preliminary data analysis to determine the reported heat exchanger performance parameters.

  6. Relationship between water chemistry and sediment mineralogy in the Cerro Prieto geothermal field: a preliminary report

    SciTech Connect

    Valette-Silver, J.N.; Thompson, J.M.; Ball, J.W.

    1981-01-01

    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.

  7. Status of non-electric use of geothermal energy in the Southern Negros geothermal field in the Philippines

    SciTech Connect

    Chua, S.E.; Abito, G.F.

    1994-07-01

    A 1-MWt multi-crop drying facility using low-enthalpy waste geothermal heat is installed within the vicinity of the Southern Negros Geothermal Project (January, 1994). The plant is envisioned to demonstrate the direct use of geothermal resources for agro-industrial purposes and at the same time, provide major benefits by raising the quality of the agro-industrial products to meet higher standards. The development and design of the heat exchangers that supply the heat and the dryer used in the facility is presented. The process flow and the dryer parameters in the drying of coconut meat and other crops have been determined. The initial design of the dryers target the dehydration of coconut meat and other crops using boxes and trays.

  8. Distributed Acoustic Sensing Technology in a Magmatic Geothermal Field - First Results From a Survey in Iceland

    NASA Astrophysics Data System (ADS)

    Reinsch, Thomas; Jousset, Philippe; Henninges, Jan; Blanck, Hanna

    2016-04-01

    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.

  9. Laboratory measurements on reservoir rocks from The Geysers geothermal field

    SciTech Connect

    Boitnott, G.N.

    1995-01-26

    A suite of laboratory measurements have been conducted on Geysers metagraywacke and metashale recovered from a drilled depth of 2599 to 2602 meters in NEGU-17. The tests have been designed to constrain the mechanical and water-storage properties of the matrix material. Various measurements have been made at a variety of pressures and at varying degrees of saturation. Both compressional and shear velocities exhibit relatively little change with effective confining pressure. In all of the samples, water saturation causes an increase in the compressional velocity. In some samples, saturation results in a moderate decrease in shear velocity greater in magnitude than would be expected based on the slight increase in bulk density. It is found that the effect of saturation on the velocities can be quantitatively modeled through a modification of Biot-Gassmann theory to include weakening of the shear modulus with saturation. The decrease is attributed to chemo-mechanical weakening caused by the presence of water. The degree of frame weakening of the shear modulus is variable between samples, and appears correlated with petrographic features of the cores. Two related models are presented through which we can study the importance of saturation effects on field-scale velocity variations. The model results indicate that the saturation effects within the matrix are significant and may contribute to previously observed field anomalies. The results help to define ways in which we may be able to separate the effects of variations in rock properties, caused by phenomena such as degree of fracturing, from similar effects caused by variations in matrix saturation. The need for both compressional and shear velocity data in order to interpret field anomalies is illustrated through comparisons of model results with the field observations.

  10. Geothermal district G1

    SciTech Connect

    Not Available

    1988-12-01

    Geothermal District G1 includes 37 northeastern California counties and six geothermal fields: Lake City, Susanville, Litchfield, Wendel, Amedee, and Casa Diablo. Electrical generation from geothermal resources occurs in three of the fields: Wendel, Amedee, and Casa Diablo. Low-temperature geothermal projects are underway throughout the district and are described in a road log format. The ten projects described are located at Big Bend, Glass Mountain, Bieber, Alturas, Cedarville, Lake City, Honey Lake Valley, Greenville, and in Sierra and Mono Counties.

  11. Surface Deformation Associated with Geothermal Fluids Extraction at the Cerro Prieto Geothermal Field, Baja California, Mexico Revealed by DInSAR Technique

    NASA Astrophysics Data System (ADS)

    Sarychikhina, O.; Glowacka, E.; Mojarro, J.

    2016-08-01

    The Differential Synthetic Aperture Radar Interferometry (DInSAR) is widely used for surface deformation detection and monitoring.In this paper, ERS-1/2, ENVISAT and RADARSAT-2 synthetic aperture radar (SAR) images acquired between 1993 and 2014 were processed to investigate the evolution of surface deformation at the Cerro Prieto geothermal field, Baja California, Mexico. The conventional DInSAR together with the interferogram stacking method was applied. Average LOS (line of sight) displacement velocity maps were generated for different periods: 1993 - 1997, 1998 - 2000, 2004, 2005, 2007, 2009, and 2012 - 2014, revealing that the area corresponding to Cerro Prieto basin presented the important surface deformation (mainly subsidence) during the entire time of investigation. The changes in the surface deformation pattern and rate were identified. These changes have a good correlation in time with the changes of production in the Cerro Prieto geothermal field.

  12. The Ahuachapan geothermal field, El Salvador: Exploitation model, performance predictions, economic analysis

    SciTech Connect

    Ripperda, M.; Bodvarsson, G.S.; Lippmann, M.J.; Witherspoon, P.A.; Goranson, C.

    1991-05-01

    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.

  13. The Ahuachapan geothermal field, El Salvador: Exploitation model, performance predictions, economic analysis

    SciTech Connect

    Ripperda, M.; Bodvarsson, G.S.; Lippmann, M.J.; Witherspoon, P.A. ); Goranson, C. )

    1991-05-01

    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.

  14. Analysis of 3d Magnetotelluric Measurements Over the Coso Geothermal Field

    NASA Astrophysics Data System (ADS)

    Newman, G. A.; Gasperikova, E.; Hoversten, M.

    2007-12-01

    We have carried out an investigation of the Coso Geothermal field utilizing a dense grid of magnetotelluric (MT) stations plus a single line of contiguous bipole array profiling over the east flank of the field. Motivation for this study is that electrical resistivity/conductivity mapping can contribute to better understanding of enhanced geothermal systems (EGS) by imaging the geometry, bounds and controlling structures in existing production, and by monitoring changes in the underground resistivity properties in the vicinity of injection due to fracture porosity enhancement. Initial analysis of the Coso MT data was carried out using 2D MT imaging technology to construct a starting 3D resistivity model from a series of 2D resistivity images obtained using the inline electric field measurements (Zxy impedance elements) along different measurement transects. This model was then refined through a 3D inversion process. The 3D resisitivity model clearly showed the controlling geological structures influencing well production at Coso and shows correlations with mapped surface features such as faults and regional geoelectric strike. We have also correlated the model with an acoustic and shear velocity model of the field to show that the near-vertical high conductivity (low resistivity) structure on the eastern flank of the producing field is also a zone of increase acoustic velocity and increased Vp/Vs ratio.

  15. Well log interpretation of certain geothermal fields in the Imperial Valley, California

    SciTech Connect

    Ershaghi, I.; Abdassah, D.

    1984-03-01

    This study reviews the wireline log responses of some geothermal fields in the Imperial Valley, California. The fields under study include the Heber, the East Mesa, the Brawley, and the Westmoreland. The well logs used in the study did not include all the wireline surveys obtained by the operators. The selected well logs obtained under special arrangements with the operators were chosen to maintain the anonymity of specific well locations but are only representative of each area. Analysis of the well logs indicates that on an individual field basis, the well logs are excellent for correlation purposes. The presence of extremely saline fluids in some fields precludes the monitoring of Q/sub v/ (cation exchange capacity per unit volume) profile for detection of hydrothermally altered zones. The producing sections in all the fields are characterized by low porosity and high resistivity.

  16. 3D Extended Logging for Geothermal Resources: Field Trials with the Geo-Bilt System

    SciTech Connect

    Mallan, R; Wilt, M; Kirkendall, B; Kasameyer, P

    2002-05-29

    Geo-BILT (Geothermal Borehole Induction Logging Tool) is an extended induction logging tool designed for 3D resistivity imaging around a single borehole. The tool was developed for deployment in high temperature geothermal wells under a joint program funded by the California Energy Commission, Electromagnetic Instruments (EMI) and the U.S. Department of Energy. EM1 was responsible for tool design and manufacture, and numerical modeling efforts were being addressed at Lawrence Livermore Laboratory (LLNL) and other contractors. The field deployment was done by EM1 and LLNL. The tool operates at frequencies from 2 to 42 kHz, and its design features a series of three-component magnetic sensors offset at 2 and 5 meters from a three-component magnetic source. The combined package makes it possible to do 3D resistivity imaging, deep into the formation, from a single well. The manufacture and testing of the tool was completed in spring of 2001, and the initial deployment of Geo-BILT occurred in May 2001 at the Lost Hills oil field in southern California at leases operated by Chevron USA. This site was chosen for the initial field test because of the favorable geological conditions and the availability of a number of wells suitable for tool deployment. The second deployment occurred in April 2002 at the Dixie Valley geothermal field, operated by Caithness Power LLC, in central Nevada. This constituted the first test in a high temperature environment. The Chevron site features a fiberglass-cased observation well in the vicinity of a water injector. The injected water, which is used for pressure maintenance and for secondary sweep of the heavy oil formation, has a much lower resistivity than the oil bearing formation. This, in addition to the non-uniform flow of this water, creates a 3D resistivity structure, which is analogous to conditions produced from flowing fractures adjacent to geothermal boreholes. Therefore, it is an excellent site for testing the 3D capability of

  17. Effect of hydrothermal alteration on rock magnetic properties from basalts in the Krafla geothermal field, Iceland

    NASA Astrophysics Data System (ADS)

    Oliva-Urcia, B.; Kontny, A.; Vahle, C.; Schleicher, A. M.

    2007-12-01

    The high-temperature Krafla geothermal field is situated within the caldera of the Krafla central volcano in NE Iceland. The last fissure eruptions (Krafla fires) occurred between 1975 and 1984. Aeromagnetic surveys from this area indicate a magnetic high corresponding to Mt. Krafla, whereas the magnetic low coincides with the caldera bottom where the Krafla geothermal field is located. The geothermal fluids are meteoric in origin and the Sudurhlídar field is boiling from depth until the surface. The permeability is higher in vertical than in horizontal profiles and the production of secondary minerals suggests a depth zonal distribution related to the temperature. The study of the magnetic properties of volcanic rocks affected by hydrothermal alteration is significant to understand magnetic anomalies related to MORB and its tectonic implications. Our study focuses in an area where the hydrothermal alteration diminishes the Ti-magnetite content of fissure subaerial lavas. The samples were taken from KH1 (200 m depth) and KH3 (400 m depth) drill cores, from the rim of the caldera. In our study we aim to correlate both, c-T curves and textural observations from the magnetic phases with the degree of hydrothermal alteration. NRM, field dependence of susceptibility (Fd) and Koenigsberg ratios (Q) from the samples are very low: NRM is < 3.1 A/m, Fd values range between 0.2 and 7.9, and Q between 0 and 6. Magnetic susceptibility varies with the magnetic mineral content. Typical textural features are shrinkage cracks from maghemitization together with exsolved textures in Ti-magnetite from high temperature oxidation. This texture is present in the deeper part of both cores (177 m in KH1 and 380 m in KH3), but KH1 samples show abundant ghost structures of Ti-magnetite, altered to a network formed by clays and Ti-oxide. A high quantity of sulphide precipitation accompanies the ghost structures. The magnetic phases strongly alter depending on the porosity of the rocks, but

  18. Guidebook to Geothermal Finance

    SciTech Connect

    Salmon, J. P.; Meurice, J.; Wobus, N.; Stern, F.; Duaime, M.

    2011-03-01

    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.

  19. Modeling studies of the Ahuachapan geothermal field, El Salvador

    SciTech Connect

    Aunzo, Z.; Steingrimsson, B.; Bodvarsson, G.S. ); Escobar, C.; Quintanilla, A. )

    1989-01-01

    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.

  20. Variations in dissolved gas compositions of reservoir fluids from the Coso geothermal field

    SciTech Connect

    Williams, Alan E.; Copp, John F.

    1991-01-01

    Gas concentrations and ratios in 110 analyses of geothermal fluids from 47 wells in the Coso geothermal system illustrate the complexity of this two-phase reservoir in its natural state. Two geographically distinct regions of single-phase (liquid) reservoir are present and possess distinctive gas and liquid compositions. Relationships in soluble and insoluble gases preclude derivation of these waters from a common parent by boiling or condensation alone. These two regions may represent two limbs of fluid migration away from an area of two-phase upwelling. During migration, the upwelling fluids mix with chemically evolved waters of moderately dissimilar composition. CO{sub 2} rich fluids found in the limb in the southeastern portion of the Coso field are chemically distinct from liquids in the northern limb of the field. Steam-rich portions of the reservoir also indicate distinctive gas compositions. Steam sampled from wells in the central and southwestern Coso reservoir is unusually enriched in both H{sub 2}S and H{sub 2}. Such a large enrichment in both a soluble and insoluble gas cannot be produced by boiling of any liquid yet observed in single-phase portions of the field. In accord with an upflow-lateral mixing model for the Coso field, at least three end-member thermal fluids having distinct gas and liquid compositions appear to have interacted (through mixing, boiling and steam migration) to produce the observed natural state of the reservoir.

  1. Movement of geothermal fluid in the Cerro Prieto field as determined from well log and reservoir engineering data

    SciTech Connect

    Halfman, S.E.; Lippmann, M.J.; Zelwer, R.

    1982-01-01

    A hydrogeologic model of the Cerro Prieto geothermal field in its undisturbed state, developed on the basis of well log and reservoir engineering data, is discussed. According to this model, geothermal fluid enters the field from the east through a deep (>10,000 ft) sandstone aquifer which is overlain by a thick shale unit which locally prevents the upward migration of the fluid. As it flows westward, the fluid gradually rises through faults and sandy gaps in the shale unit. Eventually, some of the fluid leaks to the surface in the western part of the field, while the rest mixes with surrounding colder waters.

  2. Seismic Investigations of the Murci Geothermal Field (Southern Tuscany, Italy): Preliminary Results

    NASA Astrophysics Data System (ADS)

    Riedel, M.; Alexandrakis, C.; Buske, S.

    2013-12-01

    The Monte Amiata region in the Southern Tuscany, Central Italy, describes a volcanic complex with great significance in terms of the regional fresh water supply, mining and geothermal power generation. Mainly for the latter purpose, the volcanic area of Mt Amiata has been the subject of extensive geological and geophysical research (e.g. Dini et al., 2010 and references therein). The insights from these studies have led to successful geothermal production in the Mt Amiata region since the early 1960s (e.g. Batini et al., 2003). Today's most important reservoirs in this area are the Bagnore and the Piancastagnaio fields which are both operated by the company Enel Green Power. The work presented here deals with the Murci area, another potential reservoir located about 10 km southwest of the Mt Amiata volcanic complex. Therefore, in order to get a more detailed understanding of this area, five reflection seismic profiles were carried out. We have performed on three of them a preliminary depth-migrated images, through Kirchhoff prestack depth migration (KPSDM). The vital point of depth migration algorithms is the accuracy of the velocity model that is used for the backpropagation of the seismic data. Therefore, we derived a suitable 1D starting model from nearby well logs and VSP measurements. In order to remove the large topography effects along the profiles, we then utilized first-arrival tomography for each seismic line. For the following processing we incorporated these 2D tomographic results into our starting model which compensates for static effects and improves the resolution in the near-surface area. The velocity models were then used in the application of KPSDM to the seismic data for each profile, respectively. The resulting preliminary images show a zone of high seismic reflectivity, known as the 'K-horizon' (e.g. Brogi, 2008), and could improve its geological interpretation. These promising results encourage us to proceed with deeper migration velocity

  3. Integrating Geophysical Data for the Investigation of the Chingshui Geothermal Field in Northeastern Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, P.; Song, S.; Yeh, E.; Chen, C.

    2010-12-01

    We have reviewed various surface geophysical survey results and the borehole logging data in order to better delineate the geothermal reservoir and its relative geological structures in the Chingshui area. The Chingshui geothermal field has been acknowledged to have a great potential for geothermal production in Northeast Taiwan. A pilot geothermal power plant with 3MW capacity had been built since 1981 in the area and the plant was seized to function in 1992 due to scaling problems and depletion of the steam production. Though a lot of explorations have been done in the past, there are few reservoir models established because (1) geophysical surveys were conducted in different resolutions and scales and difficult to be integrated in the same model, (2) 1-D or 2-D geophysical measurements were not integrated and re-examined in a 3-D framework for delineating the structure relationships in a 3D sense, and (3) relationships between the formation properties, such as porosities and the water saturation, and the geophysical measurements were not yet established due to lack of core samples or detailed well logging data. In this study, we utilized data from magnetotelluric and electrical resistivity surveys, as well as borehole logging measurements for constructing a general reservoir model, and tried to verify it with the borehole geophysical logging data that are collected from an open section in the geothermal test well drilled recently. Currently we have integrated different geophysical data onto the same 3D framework and tried to apply geostatistical analysis for constructing the 3D geophysical picture. Our preliminary results have revealed two low resistivity regions representing the fracture reservoir filled with hot fluids within 2000m from the surface. These regions were limited in a 2-km2 narrow area along the Chingshui river valley. The shallower low-resistivity region, Zone I, is near the surface and its bottom is at about 600-m to 800-m in depth, and it is

  4. Laboratory and field testing of improved geothermal rock bits

    SciTech Connect

    Hendrickson, R.R.; Jones, A.H.; Winzenried, R.W.; Maish, A.B.

    1980-07-01

    The development and testing of 222 mm (8-3/4 inch) unsealed, insert type, medium hard formation, high-temperature bits are described. The new bits were fabricated by substituting improved materials in critical bit components. These materials were selected on bases of their high temperature properties, machinability, and heat treatment response. Program objectives required that both machining and heat treating could be accomplished with existing rock bit production equipment. Two types of experimental bits were subjected to laboratory air drilling tests at 250/sup 0/C (482/sup 0/F) in cast iron. These tests indicated field testing could be conducted without danger to the hole, and that bearing wear would be substantially reduced. Six additional experimental bits, and eight conventional bits were then subjected to air drilling a 240/sup 0/C (464/sup 0/F) in Francisan Graywacke at The Geysers, CA. The materials selected improved roller wear by 200%, friction-pin wear by 150%, and lug wear by 150%. Geysers drilling performances compared directly to conventional bits indicate that in-gage drilling life was increased by 70%. All bits at The Geysers are subjected to reaming out-of-gage hole prior to drilling. Under these conditions the experimental bits showed a 30% increase in usable hole over the conventional bits. These tests demonstrated a potential well cost reduction of 4 to 8%. Savings of 12% are considered possible with drilling procedures optimized for the experimental bits.

  5. A tracer test at the Beowawe geothermal field, Nevada, using fluorescein and tinopal CBS

    SciTech Connect

    Rose, P.E.; Adams, M.C.; Benoit, D.

    1995-12-31

    An interwell tracer test using fluorescein and tinopal CBS was performed at the Beowawe geothermal field in north-central Nevada in order to assess the effects of recent changes to the injection strategy. Fluorescein return curves established injection-production flow patterns and verified that produced water is being reinjected into a region of the reservoir that is in excellent communication with the production wells. An analysis of the tinopal CBS return curves indicated that tinopal CBS was apparently strongly adsorbed onto the reservoir rock. The fluorescein return curves were used to estimate the overall (fractures and matrix) reservoir volume.

  6. A Geologic, Hyrologic and Geochemical Model of the Serrazzano Zone of the Larderello Geothermal Field

    SciTech Connect

    Calorie, C.; Celati, R.; D'Amore, F.; Squarci, P.; Truesdell, A.

    1980-12-16

    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.

  7. Trace element hydrochemistry indicating water contamination in and around the Yangbajing geothermal field, Tibet, China.

    PubMed

    Guo, Qinghai; Wang, Yanxin

    2009-10-01

    Thirty-eight water samples were collected at Yangbajing to investigate the water contamination resulting from natural geothermal water discharge and anthropogenic geothermal wastewater drainage. The results indicate that snow or snow melting waters, Yangbajing River waters and cold groundwaters are free from geothermal water-related contamination, whereas Zangbo river waters are contaminated by geothermal wastewaters. Moreover, there may exist geothermal springs under the riverbed of a tributary stream of Zangbo River as shown by its Cd, Li, Mo and Pb concentrations. The efforts made in this study show trace element hydrochemistry can well indicate water quality degradation related to geothermal water exploitation.

  8. Discovering new events beyond the catalogue—application of empirical matched field processing to Salton Sea geothermal field seismicity

    DOE PAGES

    Wang, Jingbo; Templeton, Dennise C.; Harris, David B.

    2015-07-30

    Using empirical matched field processing (MFP), we compare 4 yr of continuous seismic data to a set of 195 master templates from within an active geothermal field and identify over 140 per cent more events than were identified using traditional detection and location techniques alone. In managed underground reservoirs, a substantial fraction of seismic events can be excluded from the official catalogue due to an inability to clearly identify seismic-phase onsets. Empirical MFP can improve the effectiveness of current seismic detection and location methodologies by using conventionally located events with higher signal-to-noise ratios as master events to define wavefield templatesmore » that could then be used to map normally discarded indistinct seismicity. Since MFP does not require picking, it can be carried out automatically and rapidly once suitable templates are defined. In this application, we extend MFP by constructing local-distance empirical master templates using Southern California Earthquake Data Center archived waveform data of events originating within the Salton Sea Geothermal Field. We compare the empirical templates to continuous seismic data collected between 1 January 2008 and 31 December 2011. The empirical MFP method successfully identifies 6249 additional events, while the original catalogue reported 4352 events. The majority of these new events are lower-magnitude events with magnitudes between M0.2–M0.8. Here, the increased spatial-temporal resolution of the microseismicity map within the geothermal field illustrates how empirical MFP, when combined with conventional methods, can significantly improve seismic network detection capabilities, which can aid in long-term sustainability and monitoring of managed underground reservoirs.« less

  9. Discovering new events beyond the catalogue—application of empirical matched field processing to Salton Sea geothermal field seismicity

    SciTech Connect

    Wang, Jingbo; Templeton, Dennise C.; Harris, David B.

    2015-07-30

    Using empirical matched field processing (MFP), we compare 4 yr of continuous seismic data to a set of 195 master templates from within an active geothermal field and identify over 140 per cent more events than were identified using traditional detection and location techniques alone. In managed underground reservoirs, a substantial fraction of seismic events can be excluded from the official catalogue due to an inability to clearly identify seismic-phase onsets. Empirical MFP can improve the effectiveness of current seismic detection and location methodologies by using conventionally located events with higher signal-to-noise ratios as master events to define wavefield templates that could then be used to map normally discarded indistinct seismicity. Since MFP does not require picking, it can be carried out automatically and rapidly once suitable templates are defined. In this application, we extend MFP by constructing local-distance empirical master templates using Southern California Earthquake Data Center archived waveform data of events originating within the Salton Sea Geothermal Field. We compare the empirical templates to continuous seismic data collected between 1 January 2008 and 31 December 2011. The empirical MFP method successfully identifies 6249 additional events, while the original catalogue reported 4352 events. The majority of these new events are lower-magnitude events with magnitudes between M0.2–M0.8. Here, the increased spatial-temporal resolution of the microseismicity map within the geothermal field illustrates how empirical MFP, when combined with conventional methods, can significantly improve seismic network detection capabilities, which can aid in long-term sustainability and monitoring of managed underground reservoirs.

  10. Hydrology of the Greater Tongonan Geothermal system, Philippines and its implications to field exploitation

    SciTech Connect

    Seastres, J.S. Jr.; Salonga, N.D.; Saw, V.S.

    1996-12-31

    The Greater Tongonan Geothermal Field will be operating a total of 694 MWe by July 1997. The field has produced steam for the 112.5 MWe Tongonan I power plant since June 1983. With massive fluid withdrawal starting July 1996, a pre-commissioning hydrology was constructed to assess its implications to field exploitation. Pressure drawdown centered at well 106 in Mahiao was induced by fluid withdrawal at Tongonan-I production field. This drawdown will be accelerated by major steam withdrawal (734 kg/s) upon commissioning of power plants at Mahiao, Sambaloran and Malitbog sectors. To resolve this concern, fluid injection will be conducted at the periphery of Mahiao to provide recharge of reheated reinjection fluids in the reservoir. At Mahanagdong, the acidic fluid breakthrough will unlikely occur since the acidic zone north of this sector is not hydrologically well-connected to the main neutral-pH reservoir as indicated by pressure profiles.

  11. The Rotorua geothermal field, New Zealand; Its physical setting, hydrology, and response to exploitation

    SciTech Connect

    Allis, R.G.; Lumb, J.T. )

    1992-04-01

    This paper discusses the Rotorua geothermal field which contains New Zealand's only area of geyser activity that has not been significantly affected by power developments. Geophysical and geochemical investigations of the field indicate that it has an area of 18-28 km{sup 2} at about 500 m depth, and a natural heat flux of 430 {plus minus} 30 MW. About a third of its area and over half its heat and mass flux occur beneath the southern end of Lake Rotorua. Aquifer pressure beneath much of Rotorua City is controlled by the lake level, and is uniform due to high permeability in the rhyolitic host rocks. Pressure in the high temperature zone in the south east of the field is about 1.5 bar higher than the rhyolite, and is controlled by the elevation of the main discharges in the geyser area. Although significant natural changes in the geyser activity at Rotorua have occurred historically, the progressive decline of spring and geyser outflows observed since about 1970 was caused by increasing withdrawal from wells tapping geothermal fluids at up to 300 m depth beneath Rotorua City.

  12. Hydrothermal alteration in the EPF replacement wells, Olkaria Geothermal field, Kenya

    SciTech Connect

    Mungania, J.

    1996-12-31

    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.

  13. Method and apparatus for determining vertical heat flux of geothermal field

    DOEpatents

    Poppendiek, Heinz F.

    1982-01-01

    A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer (10) comprised of a length of tubing (12) of relatively low thermal conductivity with a thermopile (20) inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k.sub..infin., from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k.sub..infin., and the earth's undisturbed vertical temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.

  14. Identification of Surface Manifestation at Geothermal Field Using SAR Dual Orbit Data

    NASA Astrophysics Data System (ADS)

    Akbari, Dinul; Saepuloh, Asep

    2016-09-01

    The Wayang -Windu Geothermal Field located in West Java, Indonesia is a geothermal field under tropical zone which is identified by high precipitation, dense vegetation, and extensive weathering/alteration. The clouds due to high precipitation and vegetation conditions on the tropical zone inhibit the identification of surface manifestation using optical remote sensing techniques. In this paper, we reduced these inhibiting factors using microwave remote sensing techniques termed as Synthetic Aperture Radar (SAR). The SAR dual orbits were used to observe the targets on the surface by minimizing the effects from the clouds and dense vegetation cover. This study is aimed to identify surface manifestation based on Geo morphologic and Structural Features (GSF) of the SAR in Ascending and Descending orbits. The Linear Features Density of SAR (lifedSAR) method was applied to quantify the linear features of the ground surface and served as basis of surface manifestation identification. Based on the lifedSAR and field observations, the surface manifestations could be detected succesfully at Wayang and Cibolang craters with density about 45%. The soil measurements were used validate the result and to interpret the correlation between LFD and surface manifestations.

  15. Coupled thermo-hydro-mechanical modeling of heat extraction from the Tattapani geothermal field, India

    NASA Astrophysics Data System (ADS)

    Nand Pandey, Sachchida; Vishal, Vikram

    2017-04-01

    Modeling of coupled thermo-hydro-mechanical processes in enhanced geothermal systems is presented using the finite element method of modeling for a 3-D domain. The reservoir consists of a single horizontal fracture surrounded by low permeable rock matrix. The flow is imposed on a fracture plane, consisting of a doublet system. The reservoir rock mechanical properties were taken from the field data of the Tattapani geothermal field, India. We investigate the effects of injection temperature and mass flow rate on the energy output. The results indicate that temperature and pressure changes within the reservoirs occur due to injection of cold water. The temperature drop and fluid overpressure inside the reservoirs/fracture affect the transport properties of the fracture. The spatial-temporal variations of fracture aperture inside the reservoir greatly impact the thermal drawdown and therefore net energy output. The results showed that maximum aperture evolution occurs near the injection zone than the production zone. The fracture aperture evolution is a result of combined effects of thermal stress and fluid overpressure inside the fracture. The fracture opening reduces the injection pressure required to circulate the fixed volume of water. The effects of the injection temperature on heat extraction were also analyzed under different reservoir formations. The results indicate that reservoir permeability plays a significant role on heat extraction, highlighting the important effect of water losses. For each factor, it is concluded that thermal breakthrough primarily depends on injection temperate, mass flow rate, reservoir permeability and well distances. The results of this study can help in choosing the operational parameters for successful operation of geothermal system. The study will also be helpful to optimize the EGS performance under varying reservoir conditions.

  16. Thermal and petrologic constraints on the lower crustal melt accumulation in the Salton Sea Geothermal Field

    NASA Astrophysics Data System (ADS)

    Karakas, O.; Dufek, J.; Mangan, M.; Wright, H. M. N.

    2014-12-01

    Heat transfer in active volcanic areas is governed by complex coupling between tectonic and magmatic processes. These two processes provide unique imprints on the petrologic and thermal evolution of magma by controlling the geometry, depth, longevity, composition, and fraction of melt in the crust. The active volcanism, tectonic extension, and significantly high surface heat flow in Salton Sea Geothermal Field, CA, provides information about the dynamic heat transfer processes in its crust. The volcanism in the area is associated with tectonic extension over the last 500 ka, followed by subsidence and sedimentation at the surface level and dike emplacement in the lower crust. Although significant progress has been made describing the tectonic evolution and petrology of the erupted products of the Salton Buttes, their coupled control on the crustal heat transfer and feedback on the melt evolution remain unclear. To address these concepts, we develop a two-dimensional finite volume model and investigate the compositional and thermal evolution of the melt and crust in the Salton Sea Geothermal Field through a one-way coupled thermal model that accounts for tectonic extension, lower crustal magma emplacement, sedimentation, and subsidence. Through our simulations, we give quantitative estimates to the thermal and compositional evolution and longevity of the lower crustal melt source in the crustal section. We further compare the model results with petrologic constraints. Our thermal balance equations show that crustal melting is limited and the melt is dominated by mantle-derived material. Similarly, petrologic work on δ18O isotope ratios suggests fractional crystallization of basalt with minor crustal assimilation. In addition, we suggest scenarios for the melt fraction, composition, enthalpy release, geometry and depth of magma reservoirs, their temporal evolution, and the timescales of magmatic storage and evolution processes. These parameters provide the source

  17. Anomalously High Geothermal Gradients in the Buckman Well Field, Santa Fe County, New Mexico

    NASA Astrophysics Data System (ADS)

    Pollack, A.; Munda, R.; Farrell, T. F.; Kelley, S. A.; Frost, J.; Jiracek, G. R.

    2013-12-01

    Temperature as a function of depth was measured in ten wells in the Santa Fe, NM area as part of the Summer of Applied Geophysics Experience (SAGE) program. Eight of the wells are within 5.5 km of the city's Buckman municipal well field and two wells are at La Tierra, 16.5 km to the SE. Geothermal gradients increase from east to west towards the Buckman area, from 20°C/km at La Tierra to 76°C/km at Buckman. Within the Buckman well field, two wells on its eastern side were determined to have temperature gradients of 32°C/km and 42°C/km. Only 300 m west, the geothermal gradient sharply increases, and measured gradients reach 76 °C/km (well number SF4A), 62°C/km (SF4B), and 68°C/km (SF3A) in three shallow (<100 m) monitoring drill holes. Both local and regional causes may explain the geothermal anomaly. The short spatial wavelength of the horizontal gradient increase argues for a localized source. The unusually high gradients in three of the wells may be associated with fault-controlled, effective shallow-source, warm water upflow or with lateral flow in a shallow aquifer. On the regional level, the east to west increase in temperature gradients can be explained by deep circulating groundwater flow in the Espanola Basin and upwelling near the Rio Grande. Another possible explanation comes from gravity data gathered by SAGE over several years that shows a local NW-striking structural high in the area that could force localized convective upflow. Regional aeromag maps indicate magnetic lows exactly underneath the anomalous wells. These may be interpreted as buried volcanic plugs beneath the Buckman well field, acting as conduits for upwelling warmer waters. They may also indicate hydrothermally altered rock beneath the surface. A more nontraditional cause of the sharp thermal anomaly is also possible. The geothermal gradient anomaly coincides with the dramatic discovery by InSAR in 1993-2000 of localized ground subsidence due to excessive water well pumping

  18. Land subsidence caused by the East Mesa geothermal field, California, observed using SAR interferometry

    USGS Publications Warehouse

    Massonnet, D.; Holzer, T.; Vadon, H.

    1997-01-01

    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.

  19. Numerical Modelling and Geological Interpretation of Geothermal Fields in Black Sea

    NASA Astrophysics Data System (ADS)

    Kostyanev, Simeon; Trapov, Georgi; Dimovski, Stefan; Vasilev, Atanas; Stoyanov, Velislav; Kostadinov, Evgeni

    2013-04-01

    A numerical solution to the thermal conductivity equation was carried out along three profiles; the Varna-Sukhumi profile and two transverse profiles. The purpose of this paper is a more detailed study of the distribution in depth of the thermal field in the light of the latest geological and geophysical data concerning the age and structure of the sedimentary rocks and the Black Sea basement. Specified seismic and tomographic data about the sedimentary formation and the region basement were obtained and employed in order to precise the results obtained from the previous studies. Calculations were carried out along a geological profile using real properties of sedimentary rocks and basement and they have shown that the regional variation of temperature along the Moho plane varies from 420 to 754° ?. The heat flow along the same plane varies from 15-20 t? 29-41 mW /m2. The part of the heat flow that is caused by radiogenic sources amounts to 17-30 mW/m2. The modelling results are presented as sections that illustrate the distribution of temperature and heat flow in depth. This article is initiated by the fact that between 1st January 2009 and 12th December 2011, Project # 226592, entitled "UP-GRADE BLACK SEA SCIENTIFIC NETWORK", was worked out as part of the Seventh Framework Program (FP7). A team from the University of Mining and Geology, Sofia, took part in the project developing a geothermal database for the Black Sea basin. Part of the data was employed for the modeling of then geothermal field along the Varna-Sukhumi Profile. A catalogue is being prepared that is going to comprise all geothermal data of the Black Sea that are available so far and that amount more than 750 at present. The authors wish to thank the Project Management for the provided opportunity to work on this problem. The numerical modelling the analysis and interpretation of geothermal data will contribute to the study of the geological evolution of the lithosphere of the Black Sea depression.

  20. Icelandic basaltic geothermal field: A natural analog for nuclear waste isolation in basalt

    SciTech Connect

    Ulmer, G.C.; Grandstaff, D.E. . Dept. of Geology)

    1984-11-21

    Analog studies of Icelandic geothermal fields have shown that the design of nuclear waste repositories in basalt can benefit by comparison to the data base already available from the development of these geothermal fields. A high degree of similarity exists between these two systems: their petrology, groundwater geochemistry, mineral solubilities, hydrologic parameters, temperature ranges, water-rock redox equilibria, hydrothermal pH values, and secondary mineralogies all show considerable overlap in the range of values. The experimentally-simulated hydrothermal studies of the basaltic nuclear waste repository rocks have, at this time, produced a data base that receives a strong confirmation from the Icelandic analog. Furthermore, the Icelandic analog should eventually be employed to extrapolate into higher and lower temperatures, into longer time-base chemical comparisons, and into more realistic mineral deposition studies, than have been possible in the laboratory evaluations of the nuclear waste repository designs. This eventual use of the Icelandic analog will require cooperative work with the Icelandic Geological Survey. 46 refs., 4 figs., 2 tabs.

  1. Interpretation of radon concentration in the Serrazzano zone of the Larderello geothermal field

    SciTech Connect

    Semprini, L.; Kruger, P.; D'Amore, F.

    1982-01-01

    Wellhead concentrations of radon were made at 22 wells in the south-west region of the Larderello geothermal fields by two analytical methods, a field measurement and a laboratory measurement. The radon concentrations were correlated with average specific volume of superheated steam for each well estimated from available thermodynamic parameters of the reservoir. The correlation was improved by adjusting the specific volume of steam by a mass steam saturation value calculated at the boiling front from chemical fluid composition for each well by a method developed by D'Amore and Celati. A compressible flow model for radon transport developed by Sakakura et al. was also tested. The results confirm that radon behavior in geothermal systems is characterized by thermodynamic conditions in the reservoir. In the Serrazzano zone, abnormally high values of radon concentration with respect to estimated specific volume in four of the 22 wells were observed in an area of proposed low permeability. The high values may also result from higher emanating power or lower porosity in this zone. A cross-section normal to the zone of low permeability between the two basins shows a similar radon profile as noted in a Geysers production zone. A comparison of these data with the set obtained in 1976 by D'Amore shows relatively constant radon concentration despite several wells having large variations in gas/steam ratios.

  2. Laboratory measurements of reservoir rock from the Geysers geothermal field, California

    USGS Publications Warehouse

    Lockner, D.A.; Summers, R.; Moore, D.; Byerlee, J.D.

    1982-01-01

    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.

  3. Preliminary study in phase tensor analysis of magnetotelluric data: Case study of "X" geothermal field data

    NASA Astrophysics Data System (ADS)

    Dewi, Mayvita; Widodo, Raharjo, Imam B.

    2017-07-01

    Magnetotelluric method is commonly used for geothermal investigation due to its ability to image changes in resistivity distribution from the greater depth. However, the field magnetotelluric data is affected by distribution of geometry and conductivity heterogeneity near the surface. It can distort the magnetotelluric data response. In order to resolve the problem, the phase tensor analysis has been conducted in this paper. Phase tensor analysis has been implemented to "X" geothermal field data. The results show that the dimensionality of the area is closed to 2D from the frequency of 0.5 to 10-2 Hz, and is 3-D for lower frequency. While, the resistivity analysis has shown that the strike direction of the measurement area is N0°E - N18°E, with 90° ambiguity, or N90°E-N108°E. The resistivity increases with the depth and a conductive layer detected on the southern part of the study area.

  4. An exploitation model and performance predictions for the Ahuachapan Geothermal field, El Salvador

    SciTech Connect

    Ripperda, M.; Bodvarsson, G.S.; Lippmann, L. ); Cuellar, G.; Escobar, C. )

    1991-01-01

    This paper reports on the Ahuachapan geothermal field in El Salvador which has been producing electrical power since 1975. The power plant currently generates at approximately 50 per cent of its total installed capacity of 95 MW{sub c} because of a substantial reservoir pressure drawdown and limited drilling of make-up wells. The focus of this study is to develop means for increasing the power production over the next 30 years. One possible option is to devise an injection scheme to decrease the pressure decline and increase the energy recovery from the reservoir. Another possibility is to drill step-out wells to increase the size of the wellfield. A three-dimensional numerical model of the field has been developed to determine the effects of injection and expanded fluid production. The model was used to predict the responses of the existing and proposed production wells for different levels of electrical power generation. The overall reservoir response to different exploitation and injection scenarios was also investigated. The model predicts that the geothermal system can provide steam to generate 90 MW{sub c} for no more than 20 y, even with reinjection and a large-scale drilling program. The results also indicate that the system can produce about 75 MW{sub c} for a 30-y period with significant reinjection and the drilling of about 20 new production wells.

  5. Repetitive precision gravity studies at the Cerro Prieto and Heber geothermal fields

    SciTech Connect

    Grannell, R.B.

    1982-09-01

    To study subsidence and mass removal, a precise gravity network was established on 60 permanent monuments in the Cerro Prieto geothermal field in early 1978, and repeated annually through early 1981; the survey was tied to two bedrock sites outside the limits of the current production zone. The looping technique of station occupation was utilized, in which occupation of the base was followed by occupation of several stations, followed by a return to the base. Use of two LaCoste and Romberg gravity meters, and replication of values within loops as well as entire loops, enhanced precision such that the median standard deviations of the base-to-station differences, reduced to observed gravity values, ranged from 7 to 15 microgals for individual surveys. The smaller values were obtained as field and data reduction techniques were improved and experience was gained. A similar survey was initiated in the Heber area just north of the Mexican border in early 1980. It too was established on permanent monuments, was tied to bedrock stations outside the geothermal area, and used multiple repetitions of values with two meters to achieve high precision.

  6. Microearthquakes at the puhagan geothermal field, Philippines — A case of induced seismicity

    NASA Astrophysics Data System (ADS)

    Bromley, C. J.; Pearson, C. F.; Rigor, D. M.; PNOC-EDC

    1987-04-01

    The Puhagan area in Southern Negros is the only known Philippine geothermal field where there is a clear correlation between increased levels of local seismicity, and the development and early production phases of a geothermal power project. During commissioning of the Palinpinon I power plant in May 1983, a large increase in the microseismic event rate, occasionally exceeding 100 events per day, was noted. This seismic activity is characterized by swarms of events lasting from several hours to a month, separated by long periods of reduced activity. The largest events have local magnitudes of 2.4. Because the swarms appear to be triggered by both reinjection and production of fluids, it is difficult to relate them to a single triggering mechanism. An epicenter study was conducted during July to October 1983, using a simplified joint determination algorithm modified for a uniform velocity structure. The vast majority of the hypocenters occur in a narrow zone with a WNW lineation in the production sector of the field (correlating with a known fault trace) with very little activity in the reinjection sector (1 km to the north). First motions suggest activity has been induced on several non-parallel faults in the area, however, a majority of the events are consistent with normal faulting or oblique slip on steeply dipping NW-SE-trending planes.

  7. Geochemical analysis of fluid mineral relations in the Tiwi Geothermal Field, Philippines

    SciTech Connect

    Bruton, C.J.; Moore, J.N.; Powell, T.S.

    1997-01-01

    Geochemical modeling simulations are being used to examine the source of the reservoir fluids in the Tiwi geothermal field and to evaluate the chemical and physical processes responsible for producing observed vein parageneses. Such information can be used to trace the evolution of the Tiwi geothermal field through time. The React geochemical modeling code was used to simulate the effects of isothermal and isoenthalpic boiling, conductive cooling and heating, and incorporation of condensed steam, on fluids from the Matalibong area. Predicted mineral stabilities were used to identify mineral indicators for each process. Calcite and anhydrite precipitation were favored by conductive heating, while illite precipitation was favored when condensed steam was added to the reservoir fluid. Reconstructed downhole fluids from borehole Mat-25 are acidic and are consistent with the presence of illite as the latest alteration mineral in veins. The processes of isothermal and isoenthalpic boiling could be differentiated from conductive cooling by the presence of epidote and/or calcite during boiling, and illite during cooling. Both boiling and cooling favored precipitation of quartz, K-feldspar, wairakite, and pyrite. Ratios of Na, Cl, and Br in waters from the Matalibong are relative to seawater indicate a significant component of seawater in reservoir fluids.

  8. Investigation of fault structures from microseismicity in the Wairakei geothermal field, New Zealand

    NASA Astrophysics Data System (ADS)

    Kim, Jongchan; Boese, Carolin; Andrews, Jennifer; Sepulveda, Favian; Archer, Rosalind; Malin, Peter

    2014-05-01

    The Wairakei geothermal field is located in the centre of a NNE-trending rifting arc, called the Taupo Volcanic Zone (TVZ), New Zealand. In 1958, commercial production of electricity started at the Wairakei field, which currently holds the largest installed capacity of the TVZ (~375 MWe). For some operational reasons, large scale infield re-injection started in the mid 1990's (Otupu area; east of Wairakei) and further extended to the south (Karapiti area) in August 2011. Small scale re-injection trials have been also being conducted since 2012 (West of Wairakei). In total, 13 borehole seismometers have been installed in the Wairakei geothermal field since 2009 to support reservoir management and drilling strategies, and observe the reservoir response to production and injection. The range of installation depths is 65 m to 1,200 m. About 97% of the 7049 events recorded have magnitude ≤2, in the so-called micro-earthquake range, and locate above 6 km depth. The micro-seismicity distribution tends to be diffuse. Although some correlation with geological units and faults can be made, identification of distinct fractures is challenging. In this study, we investigate active fault structures from micro-seismic events occurring in the geothermal field between March 2009 and June 2013 using focal mechanism, clustering and double-difference relocation methods. We firstly calculate double-couple focal mechanism solutions from the micro-seismic data set using HASH. To reduce uncertainty of focal mechanism parameters, P-wave first motion polarities from 12 GeoNet stations installed in the vicinity of the Wairakei were combined with those of 13 Wairakei stations within the field. In total, 21 focal mechanisms with more than eight P-wave polarities have been computed. Most focal mechanisms are consistent in showing a NNE-trending nodal plane, and have normal or strike-slip mechanisms, coinciding well with the overall extensional tectonic regime and mapped active faults in the

  9. 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

    NASA Astrophysics Data System (ADS)

    Todaka, Norifumi; Akasaka, Chitoshi; Xu, Tianfu; Pruess, Karsten

    2004-05-01

    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.

  10. Reactive geothermal transport simulation to study the formation mechanism of impermeable barrier between acidic and neutral fluid zones in the Onikobe geothermal field, Japan

    SciTech Connect

    Todaka, Noritumi; Akasaka, Chitosi; Xu, Tianfu; Pruess, Karsten

    2003-03-06

    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.

  11. Thermal-hydrodynamic-chemical (THC) modeling based on geothermal field data

    SciTech Connect

    Kiryukhin, Alexey; Xu, Tianfu; Pruess, Karsten; Apps, John; Slovtsov, Igor

    2002-01-01

    Data on fluid chemistry and rock mineralogy are evaluated for a number of geothermal fields located in the volcanic arc of Japan and Kamchatka, Russia, Common chemical characteristics are identified and used to define scenarios for detailed numerical modeling of coupled thermal hydrodynamic chemical (THC) processes. The following scenarios of parental geothermal fluid upflow were studied: (1) single-phase conditions, 260 C at the bottom ( Ogiri type); (2) two-phase conditions, 300 C at the bottom ( Hatchobaru type); and (3) heat pipe conditions, 260 C at the bottom ( Matsukawa type). THC modeling for the single-phase upflow scenario shows wairakite, quartz, K-feld spar and chlorite formed as the principal secondary minerals in the production zone, and illite-smectite formed below 230 C. THC modeling of the two-phase upflow shows that quartz, K-feldspar (microcline), wairakite and calcite precipitate in the model as principal secondary minerals in the production zone. THC modeling of heat pipe conditions shows no significant secondary deposition of minerals (quartz, K-feldspar, zeolites) in the production zone. The influence of thermodynamic and kinetic parameters of chemical interaction, and of mass fluxes on mineral phase changes, was found to be significant, depending on the upflow regime. It was found that no parental geothermal fluid inflow is needed for zeolite precipitation, which occurs above 140 C in saturated andesite, provided that the porosity is greater than 0.001. In contrast, quartz and K-feldspar precipitation may result in a significant porosity reduction over a hundred-year time scale under mass flux conditions, and complete fracture sealing will occur given sufficient time under either single-phase or two-phase upflow scenarios. A heat pipe scenario shows no significant porosity reduction due to lack of secondary mineral phase deposition.

  12. PNAS Plus: Origin of first cells at terrestrial, anoxic geothermal fields

    NASA Astrophysics Data System (ADS)

    Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.

    2012-04-01

    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.

  13. CNCC Craig Campus Geothermal Project: 82-well closed loop GHP well field to provide geothermal energy as a common utilitiy for a new community college campus

    SciTech Connect

    Chevron Energy Solutions; Matt Rush; Scott Shulda

    2011-01-03

    Colorado Northwestern Community College (CNCC) is working collaboratively with recipient vendor Chevron Energy Solutions, an energy services company (ESCO), to develop an innovative GHP project at the new CNCC Campus constructed in 2010/2011 in Craig, Colorado. The purpose of the CNCC Craig Campus Geothermal Program scope was to utilize an energy performance contracting approach to develop a geothermal system with a shared closed-loop field providing geothermal energy to each building's GHP mechanical system. Additional benefits to the project include promoting good jobs and clean energy while reducing operating costs for the college. The project has demonstrated that GHP technology is viable for new construction using the energy performance contracting model. The project also enabled the project team to evaluate several options to give the College a best value proposition for not only the initial design and construction costs but build high performance facilities that will save the College for many years to come. The design involved comparing the economic feasibility of GHP by comparing its cost to that of traditional HVAC systems via energy model, financial life cycle cost analysis of energy savings and capital cost, and finally by evaluating the compatibility of the mechanical design for GHP compared to traditional HVAC design. The project shows that GHP system design can be incorporated into the design of new commercial buildings if the design teams, architect, contractor, and owner coordinate carefully during the early phases of design. The public also benefits because the new CNCC campus is a center of education for the much of Northwestern Colorado, and students in K-12 programs (Science Spree 2010) through the CNCC two-year degree programs are already integrating geothermal and GHP technology. One of the greatest challenges met during this program was coordination of multiple engineering and development stakeholders. The leadership of Principle Investigator

  14. Characteristics of fractures based on FMI logs and cores in well WD-1 in the Kakkonda geothermal field, Japan

    SciTech Connect

    Kato, O.; Doi, N.; Sakagawa, Y.

    1995-12-31

    The Formation MicroImager (FMI) logs and some cores have clarified continuously the bedding plane transition and the fracture distribution in an interval of 60-1,505 m depth in NEDO`s exploration well WD-1. A frequency of fractures analyzed from FMI logs is correlative to the permeable zone in the Kakkonda geothermal reservoir. Particularly, the result of FMI interpretation around 980.70 m where there was a circulation loss, verifies the structure of the F-1 fracture in the Kakkonda geothermal field. On the basis of orientations of drilling induced fractures and borehole breakouts analyzed from FMI logs in 60-2,550 m depth, the horizontal maximum stress axis does not change at least from surface to 2,200 m depth in the Kakkonda geothermal field.

  15. An Experiment to Test Geophysical Methods For Monitoring Fluid Re-Injection at the Wairakei Geothermal Field, New Zealand

    NASA Astrophysics Data System (ADS)

    Jiracek, G. R.; Bowles-Martinez, E.; Feucht, D. W.; Ryan, J.; Caldwell, T. G.; Bannister, S. C.; Bertrand, T.; Bennie, S.; Bourguignon, S.

    2010-12-01

    The National Science Foundation (NSF) is supporting US students to participate in GNS Science’s geothermal research program supported by the New Zealand Government. The NSF international program aims to quick-start a new generation of geothermal-oriented US geophysics students who will be poised to be active participants and leaders in US geothermal energy development. This year’s project evaluated joint passive seismic and magnetotelluric (MT) field measurements to determine three-dimensional (3-D) reservoir characteristics during fluid withdrawal and re-injection. A preliminary test of the ability to achieve repeatable MT data in high noise locations was carried out in the Wairakei geothermal field using a 14-site base-line MT survey and repeat occupations at four sites. Different data processing schemes identified MT frequency bands where impedance phase tensor data were most sensitive to known variables such as daily solar source variations, wind, and drilling operations. Other frequency bands were identified where good MT repeatability will allow further tests. A streamlined method was developed for visualizing 3-D earthquake focal mechanisms resulting from production changes in geothermal reservoirs. The computer program allows spatial sorting of seismic events and thus subsurface fracture identification.

  16. 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)

    SciTech Connect

    Smith, C.S.; Ellis, P.F. II

    1983-05-01

    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)

  17. Analysis and interpretation of stress indicators in deviated wells of the Coso Geothermal Field

    USGS Publications Warehouse

    Schoenball, Martin; Glen, Jonathan M. G.; Davatzes, Nicholas C.

    2016-01-01

    Characterizing the tectonic stress field is an integral part of the development of hydrothermal systems and especially for enhanced geothermal systems (EGS). With a well characterized stress field the propensity of fault slip on faults with known location and orientation can be identified. Faults that are critically oriented for faulting with respect to the stress field are known to provide natural fluid pathways. A high slip tendency makes a fault a likely candidate for reactivation during the creation of an EGS. Similarly, the stress state provides insight for the potential of larger, damaging earthquakes should extensive portions of well-oriented, larger faults be reactivated.The analysis of stress indicators such as drilling-induced fractures and borehole breakouts is the main tool to infer information on the stress state of a geothermal reservoir. The standard procedure is applicable to sub-vertical wellbore sections and highly deviated sections have to be discarded. However, in order to save costs and reduce the environmental impact most recent wells are directionally drilled with deviations that require appropriate consideration of the deviated trajectory. Here we present an analysis scheme applicable to arbitrary well trajectories or a combination of wells to infer the stress state. Through the sampling of the stress tensor along several directions additional information on the stress regime and even relative stress magnitudes can be obtained. We apply this method on image logs from the pair of wells 58-10 and 58A-10 that were drilled from the same well pad. Both wells have image logs of about 2km of their trajectories that are separated by less than 300m. For both wells we obtain a mean orientation of SHmax of N23° with large standard deviations of locations of stress indicators of 24° and 26°, respectively. While the local stress direction is highly variable along both wells with dominant wavelengths from around 50 to 500m, the mean directions are very

  18. GEOTHERM Data Set

    DOE Data Explorer

    DeAngelo, Jacob

    1983-01-01

    GEOTHERM is a comprehensive system of public databases and software used to store, locate, and evaluate information on the geology, geochemistry, and hydrology of geothermal systems. Three main databases address the general characteristics of geothermal wells and fields, and the chemical properties of geothermal fluids; the last database is currently the most active. System tasks are divided into four areas: (1) data acquisition and entry, involving data entry via word processors and magnetic tape; (2) quality assurance, including the criteria and standards handbook and front-end data-screening programs; (3) operation, involving database backups and information extraction; and (4) user assistance, preparation of such items as application programs, and a quarterly newsletter. The principal task of GEOTHERM is to provide information and research support for the conduct of national geothermal-resource assessments. The principal users of GEOTHERM are those involved with the Geothermal Research Program of the U.S. Geological Survey.

  19. Relationships among seismic velocity, metamorphism, and seismic and aseismic fault slip in the Salton Sea Geothermal Field region

    USGS Publications Warehouse

    McGuire, Jeffrey J.; Lohman, Rowena B.; Catchings, Rufus D.; Rymer, Michael J.; Goldman, Mark R.

    2015-01-01

    The Salton Sea Geothermal Field is one of the most geothermally and seismically active areas in California and presents an opportunity to study the effect of high-temperature metamorphism on the properties of seismogenic faults. The area includes numerous active tectonic faults that have recently been imaged with active source seismic reflection and refraction. We utilize the active source surveys, along with the abundant microseismicity data from a dense borehole seismic network, to image the 3-D variations in seismic velocity in the upper 5 km of the crust. There are strong velocity variations, up to ~30%, that correlate spatially with the distribution of shallow heat flow patterns. The combination of hydrothermal circulation and high-temperature contact metamorphism has significantly altered the shallow sandstone sedimentary layers within the geothermal field to denser, more feldspathic, rock with higher P wave velocity, as is seen in the numerous exploration wells within the field. This alteration appears to have a first-order effect on the frictional stability of shallow faults. In 2005, a large earthquake swarm and deformation event occurred. Analysis of interferometric synthetic aperture radar data and earthquake relocations indicates that the shallow aseismic fault creep that occurred in 2005 was localized on the Kalin fault system that lies just outside the region of high-temperature metamorphism. In contrast, the earthquake swarm, which includes all of the M > 4 earthquakes to have occurred within the Salton Sea Geothermal Field in the last 15 years, ruptured the Main Central Fault (MCF) system that is localized in the heart of the geothermal anomaly. The background microseismicity induced by the geothermal operations is also concentrated in the high-temperature regions in the vicinity of operational wells. However, while this microseismicity occurs over a few kilometer scale region, much of it is clustered in earthquake swarms that last from

  20. The Bulalo geothermal field, Philippines: Reservoir characteristics and response to production

    SciTech Connect

    Clemente, W.C.; Villadolid-Abrigo, F.L.

    1993-10-01

    The Bulalo geothermal field has been operating since 1979, and currently has 330 MWe of installed capacity. The field is associated with a 0.5 Ma dacite dome on the southeastern flank of the Late Pliocene to Quaternary Mt. Makiling stratovolcano. The reservoir occurs within pre-Makiling andesite flows and pyroclastic rocks capped by the volcanic products of Mt. Makiling. Initially, the reservoir was liquid-dominated with a two-phase zone overlying the neutral-pH liquid. Exploitation has resulted in an enlargement of the two-phase zone, return to the reservoir of separated waste liquid that has been injected, scaling in the wellbores and rock formation, and influx of cooler groundwaters. Return of injected waters to the reservoir and scaling have been the major reservoir management concerns. These have been mitigated effectively by relocating injection wells farther away from the production area and by dissolving scale from wells with an acid treatment.

  1. Pre-exploitation state of the Ahuachapán geothermal field, El Salvador

    USGS Publications Warehouse

    Aunzo, Z.; Laky, C.; Steingrimsson, B.; Bodvarsson, G.S.; Lippmann, M.J.; Truesdell, A.H.; Escobar, C.; Quintanilla, A.; Cuellar, G.

    1991-01-01

    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.

  2. East Olkaria Geothermal Field, Kenya: 2. Predictions of well performance and reservoir depletion

    NASA Astrophysics Data System (ADS)

    Bodvarsson, Gudmundur S.; Pruess, Karsten; Stefansson, Valgardur; Bjornsson, Sveinbjorn; Ojiambo, Sebastian B.

    1987-01-01

    Performance predictions are presented for the East Olkaria geothermal field, using a three-dimensional well-by-well model calibrated against 6.5 years of production history. Various reservoir development schemes are investigated to study the effects of different well spacing on well deliverabilities, power production of 45 and 105 MWe (megawatts electric), and the effects of injection on well performance and reservoir depletion. It is shown that the present well density at Olkaria (20 wells/km2) is too high; recommended well density for future wells is 11 wells/km2 (300-m well spacing). The present production area at East Olkaria (2 km2) is capable of 45 MWe power production for a 30-year period, but 105 MWe power production requires a well field area of about 9.5 km2, which may not exist. Injection can help sustain steam flow rates from wells, thus reducing the need for new development wells.

  3. Hydrogeology of the Owego-Apalachin Elementary School Geothermal Fields, Tioga County, New York

    USGS Publications Warehouse

    Williams, John H.; Kappel, William M.

    2015-12-22

    The specific conductance of the saline water from the shallower fractured zone in the southwest field was about 16,000 microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25°C), and that from the fractured zone in the northeast field was about 65,000 μS/cm at 25°C. The saline waters were characterized by a chemical composition similar to that of deep formation brines collected from oil and gas wells in the Appalachian Basin. About 40 percent of the geothermal wells discharged methane gas to land surface during and (or) following drilling. Sandstone beds at depths of 348 to 378 ft bls are the likely source of the methane gas, which was determined to be early thermogenic in origin.

  4. Compilation of gas geochemistry and isotopic analyses from The Geysers geothermal field: 1978-1991

    USGS Publications Warehouse

    Lowenstern, Jacob B.; Janik, Cathy; Fahlquist, Lynne; Johnson, Linda S.

    1999-01-01

    We present 45 chemical and isotopic analyses from well discharges at The Geysers geothermal field and summarize the most notable geochemical trends. H2 and H2S concentrations are highest in the Southeast Geysers, where steam samples have δD and δ18O values that reflect replenishment by meteoric water. In the Northwest Geysers, samples are enriched in gas/steam, CO2, CH4, and N2/Ar relative to the rest of the field, and contain steam that is elevated in δD and δ18O, most likely due to substantial contributions from Franciscan-derived fluids. The δ13C of CO2, trends in CH4 vs. N2, and abundance of NH3 indicate that the bulk of the non-condensable gases are derived from thermal breakdown of organic materials in Franciscan meta-sediments.

  5. Phase 2 and 3 Slim Hole Drilling and Testing at the Lake City, California Geothermal Field

    SciTech Connect

    Dick Benoit; David Blackwell; Joe Moore; Colin Goranson

    2005-10-27

    temperatures of 270 to 310 oF), intermediate (elevation 2800 to 3700 ft and temperatures 270 to 320 oF ) and deep (elevations < 1000 ft and temperatures 323 to 337 oF) components. In the south part of the field, near Phipps #2 the shallow and deep components are present. In the central part of the field, near OH-1 the shallow and intermediate components are present and presumably the deep component is also present. In the north part of the field, the intermediate and deep components are present. Most or all of the fractures in the core have dips between 45 degrees and vertical and no strong stratigraphic control on the resource has yet been demonstrated. Conceptually, the Lake City geothermal resource seems to be located along the north-south trending range front in a relatively wide zone of fractured rock. The individual fractures do not seem to be associated with any readily identifiable fault. In fact, no major hydraulically conductive faults were identified by the core drilling.

  6. Hydrothermal Alteration in Submarine Basaltic Rocks from the Reykjanes Geothermal Field, Iceland. (Invited)

    NASA Astrophysics Data System (ADS)

    Zierenberg, R. A.; Schiffman, P.; Fowler, A. P.; Marks, N.; Fridleifsson, G.; Elders, W. A.

    2013-12-01

    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

  7. Modelling chloride and CO{sub 2} chemistry at the Wairakei geothermal field, New Zealand

    SciTech Connect

    Kissling, W.M.; White, S.P.; O'Sullivan, M.J.; Bullivant, D.P.; Brown, K.L.

    1996-01-24

    The chloride and CO2 chemistry at the Wairakei geothermal field, New Zealand has been modelled using an extended version of the geothermal simulator TOUGH2 which solves the equations for the transport of reacting chemical species in multi-phase fluids. Reactions involving the speciation of aqueous CO2 to H2CO3 and HCO3-, are included in the model. Because CO2 speciation in water is pH dependent, a reaction involving the most important weak acid buffer at Wairakei (H4SiO4) has also been included. A ‘Henry’s Law’ reaction expresses the equilibrium between the aqueous and vapour components of CO2. The chloride is treated as a conservative, non-reacting species which is present only in the liquid phase. Results from the model are compared with measured chloride and CO2 data from Wairakei covering the period 1959 to 1987.

  8. Salton Sea Geothermal Field, Imperial Valley, California as a site for continental scientific drilling. [Abstract only

    SciTech Connect

    Elders, W.A.; Cohen, L.H.

    1983-03-01

    The Salton Trough, where seafloor spreading systems of the East Pacific Rise transition into the San Andreas transform fault system, is the site of such continental rifting and basin formation today. The largest thermal anomaly in the trough, the Salton Sea Geothermal Field (SSGF), is of interest to both thermal regimes and mineral resources investigators. At this site, temperatures >350/sup 0/C and metal-rich brines with 250,000 mg/L TDS have been encountered at <2 km depth. Republic Geothermal Inc. will drill a new well to 3.7 km in the SSGF early in 1983; we propose add-on experiments in it. If funded, we will obtain selective water and core samples and a large-diameter casing installed to 3.7 km will permit later deepening. In Phase 2, the well would be continuously cored to 5.5 km and be available for scientific studies until July 1985. The deepened well would encounter hydrothermal regimes of temperature and pressure never before sampled.

  9. Plant adaptation to extreme environments: the example of Cistus salviifolius of an active geothermal alteration field.

    PubMed

    Bartoli, Giacomo; Bottega, Stefania; Forino, Laura M C; Ciccarelli, Daniela; Spanò, Carmelina

    2014-02-01

    Cistus salviifolius is able to colonise one of the most extreme active geothermal alteration fields in terms of both soil acidity and hot temperatures. The analyses of morpho-functional and physiological characters, investigated in leaves of plants growing around fumaroles (G leaves) and in leaves developed by the same plants after transfer into growth chamber under controlled conditions (C leaves) evidenced the main adaptive traits developed by this pioneer plant in a stressful environment. These traits involved leaf shape and thickness, mesophyll compactness, stomatal and trichome densities, chloroplast size. Changes of functional and physiological traits concerned dry matter content, peroxide and lipid peroxidation, leaf area, relative water and pigment contents. A higher reducing power and antioxidant enzymatic activity were typical of G leaves. Though the high levels of stress parameters, G leaves showed stress-induced specific morphogenic and physiological responses putatively involved in their surviving in active geothermal habitats. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  10. The hydrological model of the Mahanagdong sector, Greater Tongonan Geothermal Field, Philippines

    SciTech Connect

    Herras, E.B.; Licup, A.C. Jr.; Vicedo, R.O.

    1996-12-31

    The Mahanagdong sector of the Greater Tongonan Geothermal Field is committed to supply 180 MWe of steam by mid-1997. An updated hydrological model was constructed based on available geoscientific and reservoir engineering data from a total of 34 wells drilled in the area. The Mahanagdong; resource is derived from a fracture-controlled and volcano hosted geothermal system characterized by neutral to slightly alkali-chloride fluids with reservoir temperatures exceeding 295{degrees}C. A major upflow region was identified in the vicinity of MG-3D, MG-14D and MG-5D. Isochemical contours indicate outflowing fluids with temperatures of 270-275{degrees}C to the south and west. Its southwesterly flow is restricted by the intersection of the impermeable Mahanagdong Claystone near MG-10D, which delimits the southern part of the resource. Low temperature (<200{degrees}C), shallow inflows are evident at the west near MG-4D and MG-17D wells which act as a cold recharge in this sector.

  11. Radon and thoron analysis of soil gas survey case study of Rajabasa geothermal field

    NASA Astrophysics Data System (ADS)

    Haerudin, Nandi; Wahyudi, Suryanto, Wiwit

    2013-09-01

    Radon and Thoron concentration of soil gas was measured by Scintrex Radon detector RDA 200 in the Rajabasa geothermal field, South Lampung regency, Indonesia. This study is aimed todeterminethe buried fault zoneunder theoverburdenlayer. The survey areacovers three geothermal manifestations in the southern part of Rajabasageothermalfield. The result indicates fault system trending SW-NE (N 60° E) and SSW-NNE (N 8° E). The contour map of Radon concentration performed high value in the three manifestations which was included survey area; those are 123 cpm in Gunung Botak hot spring, 145 cpm in Kunjir fumarole and 382 cpm about 300 m from Bulakan (Way Belerang) fumarole. Three manifestations were connected by two fault. The first fault passed begin from Gunung Botak directed to Kunjir and the other across the first fault from SSW to Bulakan. The contour map of Radon and Thoron ratio indicated that the second fault system is not only indicate the presence of the fault/fracture zones but also show the extension of the faults/fractures from the depth to the surface.

  12. A large and complete Jurassic geothermal field at Claudia, Deseado Massif, Santa Cruz, Argentina

    NASA Astrophysics Data System (ADS)

    Guido, Diego M.; Campbell, Kathleen A.

    2014-04-01

    Late Jurassic geothermal deposits at Claudia, Argentinean Patagonia, are among the largest (40 km2) and most varied in the Deseado Massif, a 60,000 km2 volcanic province hosting precious metals (Au, Ag) mineralization generated during diffuse back arc spreading and opening of the South Atlantic Ocean. Both siliceous sinter and travertine occur in the same stratigraphic sequence. Deposits range from those interpreted as fluvially reworked hydrothermal silica gels, to extensive apron terraces, to a clustering of high-temperature subaerial vent mounds. Paleoenvironmentally diagnostic textures of sinters include wavy laminated, bubble mat and nodular fabrics, and for travertines comprise fossil terracette rims, wavy laminated, bubble mat, spherulitic, oncoidal, and peloidal fabrics. Of special note is the presence of relatively large (to 25 cm high), inferred subaqueous "Conophyton" structures in travertines, which serve as analogs for some Precambrian stromatolites and imply the presence of relatively deep pools maintained by voluminous spring discharges. The Claudia geothermal field is geographically and geologically linked to the Cerro Vanguardia epithermal project (total resource of ~ 7.8 million ounces Au equivalent) via proximity, similar veins, and structural linkages, making it an especially large and relevant prospect for the region. The combined Claudia-Cerro Vanguardia hydrothermal system likely represents a fortuitous alignment of focused fluid flow and structure conducive to forming a giant epithermal ore deposit, with respect to size, ore concentration and potentially duration, in the Late Jurassic of Patagonia.

  13. Estimation of deepwater temperature and hydrogeochemistry of springs in the Takab geothermal field, West Azerbaijan, Iran.

    PubMed

    Sharifi, Reza; Moore, Farid; Mohammadi, Zargham; Keshavarzi, Behnam

    2016-01-01

    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.

  14. Observing and Modeling Temporal Variations of Seismic Velocities at the Geysers Geothermal Field, California

    NASA Astrophysics Data System (ADS)

    Lai, V. H.; Tsai, V. C.; Taira, T.

    2016-12-01

    Perturbations in subsurface elastic parameters induce changes in seismic velocity. To understand the stress perturbations due to geothermal operation, we apply seismic noise interferometry to examine the temporal variations of seismic velocity (dv/v) at the Geysers Geothermal Field, California. Our observations show a strong positive correlation between dv/v and net production (steam production minus fluid injection), and a strong negative correlation between dv/v and fluid injection. Notably, there is little time lag (less than a month) between dv/v and fluid injection in the SE region of the field, suggesting a rapid response in elastic properties in this highly saturated region. The influx of fluid decreases the effective shear modulus, which in turn decreases the velocities. A number of hypotheses have been suggested to cause stress perturbations in the field, including poroelastic-induced stresses, direct elastic loading and thermoelastic-induced stresses. We perform a 1-D hydrological simulation to calculate the expected variations in dv/v due to different stresses by considering Murnaghan's theory of finite deformations and the third-order terms in the strain energy function. The synthetic dv/v measurements are spatially averaged based on computed sensitivity kernels, allowing for direct comparison with both the amplitude and phase of dv/v observations. We show the order-of-magnitude effect that each of the stresses have on the dv/v measurement, and explore the possibility of using dv/v to constrain important hydrological and elastic properties such as hydraulic conductivity in the field.

  15. Geothermal handbook

    USGS Publications Warehouse

    1976-01-01

    The Bureau of Land Management offered over 400,000 hectares (one million acres) for geothermal exploration and development in 1975, and figure is expected to double this year. The Energy Research and Development Administration hopes for 10-15,000 megawatts of geothermal energy by 1985, which would require, leasing over 16.3 million hectares (37 million acres) of land, at least half of which is federal land. Since there is an 8 to 8-1/2 year time laf between initial exploration and full field development, there would have to be a ten-fold increase in the amount of federal land leased within the next three years. Seventy percent of geothermal potential, 22.3 million hectares (55 million acres), is on federal lands in the west. The implication for the Service are enormous and the problems immediate. Geothermal resource are so widespread they are found to some extent in most biomes and ecosystems in the western United States. In most cases exploitation and production of geothermal resources can be made compatible with fish and wildlife management without damage, if probable impacts are clearly understood and provided for before damage has unwittingly been allowed to occur. Planning for site suitability and concern with specific operating techniques are crucial factors. There will be opportunities for enhancement: during exploration and testing many shallow groundwater bodies may be penetrated which might be developed for wildlife use. Construction equipment and materials needed for enhancement projects will be available in areas heretofore considered remote projects will be available in areas heretofore considered remote by land managers. A comprehensive knowledge of geothermal development is necessary to avoid dangers and seize opportunities. This handbook is intended to serve as a working tool in the field. It anticipated where geothermal resource development will occur in the western United States in the near future. A set of environmental assessment procedures are

  16. Hydrogeochemistry of the thermal waters from the Yenice Geothermal Field (Denizli Basin, Southwestern Anatolia, Turkey)

    NASA Astrophysics Data System (ADS)

    Alçiçek, Hülya; Bülbül, Ali; Alçiçek, Mehmet Cihat

    2016-01-01

    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

  17. Paleomagnetic Reorientation of Structural Elements in Drill Cores: an example from Tolhuaca Geothermal Field

    NASA Astrophysics Data System (ADS)

    Perez-Flores, P.; Veloso, E. E.; Cembrano, J. M.; Sánchez, P.; Iriarte, S.; Lohmar, S.

    2013-12-01

    Reorientation of mesoscopic faults, veins and fractures recovered from drilling is critical to construct reliable structural models that can account for their architecture and deformation regime. However, oriented cores are expensive and time consuming to drill. Some techniques achieve reorientation by introducing tools into the borehole. Problems arise when boreholes are unstable or collapse. One alternative technique allowing reorientation is to obtain reliable paleomagnetic vectors to reorient each core piece after drilling. Here, we present stable and reliable remnant magnetic vectors calculated from the Tol-1 core to analyze the geometry of the fracture network and its relationship to regional tectonic. Tol-1 core is a vertical, 1073 m deep geothermal well, drilled at the Tolhuaca Geothermal Field in the Southern Volcanic Zone of the Andes by MRP Geothermal Chile Ltda (formerly GGE Chile SpA) in 2009. The core consists of basaltic/andesitic volcanic rocks with subordinate pyroclastic/volcaniclastic units, with probable Pleistocene age. Fault planes with slickenlines and mineral fiber kinematic indicators are common in the upper 700 m of the core. Calcite, quartz and calcite-quartz veins are recognized along of entire core, whereas epidote-quartz and calcite-epidote veins occur in the last 350 m, minor chlorite, anhydrite and clay-minerals are present. Orientations of structural features in the core were measured with a goniometer using the core's axis and a false north for each piece; hence, orientation data has a false strike but a real dip. To achieve total reorientation of the pieces, we collected 200 standard-size paleomagnetic specimens, ensuring that at least four of them were recovered from continuous pieces. Thermal (up to 700°C) and alternating field demagnetization (up to 90mT on steps of 2mT) methods were used to isolate a stable remnant magnetization (RM) vector, and each technique yielded similar results. RM vectors were recovered between 0 to 25

  18. The dependence of permeability on effective stress for an injection test in the Higashi-Hachimantai Geothermal Field

    USGS Publications Warehouse

    Nathenson, M.

    2000-01-01

    A simple inverse-power relation for the influence of effective stress on permeability is used to explain the flow behavior during an injection test at the Higashi-Hachimantai geothermal field, Japan. The new analytical expression successfully models data from the experiment involving high-pressure injection and monitoring at an observation well.

  19. Using geochemical and isotopic techniques for exploration of geothermal energy in Southern Sabalan geothermal field, NW Iran

    NASA Astrophysics Data System (ADS)

    Masoumi, Rahim

    2017-04-01

    From a hydrogeochemical point of view the geothermal fluids in the study area can be divided into two categories, (1) Na-Cl and (2) Na-Ca-HCO3. In the study area, the hot water samples depict temperature and pH ranges of 22 °C to 77 °C and 6.4 to 7.3, respectively. The total dissolved solids vary from 456 mg/L to 7006 mg/L. The concentration of rare metallic and non-metallic elements such as Li, Rb, B, Ba, Sr, CS, Se, Al, As, Hg in cold and hot spring waters in the Bushdi area were also analyzed. The utmost concentration belongs to Se which ranges from 135 mg/L to 273 mg/L. Boron also shows notable concentration values, in most samples it exceeds 20 mg/L, and in certain samples it ranges from 28 mg/L to 33.5 mg/L. The concentration value of arsenic ranges from 3 mg/L to 4 mg/L. The maximum concentration value of mercury is 0.01 mg/L. The δ18O values of these samples vary from -12.4 ‰ to -7.5 ‰ and the δD values range from -78.6 ‰ to -70.6 ‰. Plotting δ18O versus δD demonstrates that the data points are clustered close to both, the global meteoric water line (GMWL) with the equation δD = 8 δ18O + 10 and, the national meteoric water line (NMWL) with the equation δD = 6.89 δ18O + 6.57. As can be observed, the geothermal fluids in the Bushdi area show relatively slight increase in δ18O values that may be caused by interaction of hot fluids with host volcanic rocks. In fact, this relatively slight increment in δ18O values may indicate the low to moderate temperature of the geothermal system. The δD values, in general, do not show notable variation because of very low hydrogen content of the host rocks. The slight increase in δD, however, may be in conjunction with vaporization and isotopic interaction with the host rocks. The 3H content of the cold and hot waters in the Bushdi area is relatively high and varies from 0.65 TU to 41.4 TU. This may be caused either by mixing with meteoric sources or rapid fluid flow within the system in a shorter time

  20. Niland development project geothermal loan guaranty: 49-MW (net) power plant and geothermal well field development, Imperial County, California: Environmental assessment

    SciTech Connect

    Not Available

    1984-10-01

    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.

  1. Analysis of earthquake clustering and source spectra in the Salton Sea Geothermal Field

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Chen, X.

    2015-12-01

    The Salton Sea Geothermal field is located within the tectonic step-over between San Andreas Fault and Imperial Fault. Since the 1980s, geothermal energy exploration has resulted with step-like increase of microearthquake activities, which mirror the expansion of geothermal field. Distinguishing naturally occurred and induced seismicity, and their corresponding characteristics (e.g., energy release) is important for hazard assessment. Between 2008 and 2014, seismic data recorded by a local borehole array were provided public access from CalEnergy through SCEC data center; and the high quality local recording of over 7000 microearthquakes provides unique opportunity to sort out characteristics of induced versus natural activities. We obtain high-resolution earthquake location using improved S-wave picks, waveform cross-correlation and a new 3D velocity model. We then develop method to identify spatial-temporally isolated earthquake clusters. These clusters are classified into aftershock-type, swarm-type, and mixed-type (aftershock-like, with low skew, low magnitude and shorter duration), based on the relative timing of largest earthquakes and moment-release. The mixed-type clusters are mostly located at 3 - 4 km depth near injection well; while aftershock-type clusters and swarm-type clusters also occur further from injection well. By counting number of aftershocks within 1day following mainshock in each cluster, we find that the mixed-type clusters have much higher aftershock productivity compared with other types and historic M4 earthquakes. We analyze detailed spatial variation of 'b-value'. We find that the mixed-type clusters are mostly located within high b-value patches, while large (M>3) earthquakes and other types of clusters are located within low b-value patches. We are currently processing P and S-wave spectra to analyze the spatial-temporal correlation of earthquake stress parameter and seismicity characteristics. Preliminary results suggest that the

  2. Hydrogeochemical and isotopic characteristics of Kavak (Seydişehir-Konya) geothermal field, Turkey

    NASA Astrophysics Data System (ADS)

    Bozdağ, Ayla

    2016-09-01

    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

  3. A comparison of long-term changes in seismicity at The Geysers, Salton Sea, and Coso geothermal fields

    NASA Astrophysics Data System (ADS)

    Trugman, Daniel T.; Shearer, Peter M.; Borsa, Adrian A.; Fialko, Yuri

    2016-01-01

    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.

  4. Geothermal Field Development in the European Community Objectives, Achievements and Problem Areas

    SciTech Connect

    Ungemach, Pierre

    1983-12-15

    Achievements and problem areas are reviewed with respect to various engineering implications of geothermal field development in the European Community (EC). Current and furture development goals address three resource settings. (a) low enthalpy sources (30-150{degrees}C), an outlook common to all Member states as a result of hot water aquifers flowing in large sedimentary units with normal heat flow, widespread thoughout the EC; (b) high enthalpy sources (<150{degrees}C) in areas of high heat flow which, as a consequence of the geodynamics of the Eurasian plate, are limited to Central and South-West Italy and to Eastern Greece; (c) hot dry rocks (HDR), whose potential for Europe, and also the difficulties in implementing the heat mining concept, are enormous. A large scale experiment conducted at medium depth in Cornwall (UK) proves encouraging though. It has provided the right sort of scientific inputs to the understanding of the mechanics of anisotropic brittle basement rocks.

  5. Crystal size of epidotes: A potentially exploitable geothermometer in geothermal fields

    SciTech Connect

    Patrier, P.; Beaufort, D.; Touchard, G. ); Fouillac, A.M. )

    1990-11-01

    Crystal size of epidotes crystallized in quartz + epidote veins is used as the basis for a new geothermometer from the fossil geothermal field of Saint Martin (Lesser Antilles). The epidote-bearing alteration paragenesis is developed as far as 3 km from a quartz diorite pluton at temperatures of 220-350C. The length/width ratio of the epidote grains is constant for all the analyzed samples and suggests isotropic growth environments. However, the length and width of the grains vary exponentially with temperature. The obtained results offer new perspectives for simple grain-size geothermomentry but must be extended to other geologic environments to clarify the influence of different rock types.

  6. Geochemical Enhancement Of Enhanced Geothermal System Reservoirs: An Integrated Field And Geochemical Approach

    SciTech Connect

    Joseph N. Moore

    2007-12-31

    The geochemical effects of injecting fluids into geothermal reservoirs are poorly understood and may be significantly underestimated. Decreased performance of injection wells has been observed in several geothermal fields after only a few years of service, but the reasons for these declines has not been established. This study had three primary objectives: 1) determine the cause(s) of the loss of injectivity; 2) utilize these observations to constrain numerical models of water-rock interactions; and 3) develop injection strategies for mitigating and reversing the potential effects of these interactions. In this study rock samples from original and redrilled injection wells at Coso and the Salton Sea geothermal fields, CA, were used to characterize the mineral and geochemical changes that occurred as a result of injection. The study documented the presence of mineral scales and at both fields in the reservoir rocks adjacent to the injection wells. At the Salton Sea, the scales consist of alternating layers of fluorite and barite, accompanied by minor anhydrite, amorphous silica and copper arsenic sulfides. Amorphous silica and traces of calcite were deposited at Coso. The formation of silica scale at Coso provides an example of the effects of untreated (unacidified) injectate on the reservoir rocks. Scanning electron microscopy and X-ray diffractometry were used to characterize the scale deposits. The silica scale in the reservoir rocks at Coso was initially deposited as spheres of opal-A 1-2 micrometers in diameter. As the deposits matured, the spheres coalesced to form larger spheres up to 10 micrometer in diameter. Further maturation and infilling of the spaces between spheres resulted in the formation of plates and sheets that substantially reduce the original porosity and permeability of the fractures. Peripheral to the silica deposits, fluid inclusions with high water/gas ratios provide a subtle record of interactions between the injectate and reservoir rocks

  7. Temporal static stress drop variations due to injection activity at The Geysers geothermal field, California

    NASA Astrophysics Data System (ADS)

    Staszek, M.; Orlecka-Sikora, B.; Leptokaropoulos, K.; Kwiatek, G.; Martínez-Garzón, P.

    2017-07-01

    We use a high-quality data set from the NW part of The Geysers geothermal field to determine statistical significance of temporal static stress drop variations and their relation to injection rate changes. We use a group of 322 seismic events which occurred in the proximity of Prati-9 and Prati-29 injection wells to examine the influence of parameters such as moment magnitude, focal mechanism, hypocentral depth, and normalized hypocentral distances from open-hole sections of injection wells on static stress drop changes. Our results indicate that (1) static stress drop variations in time are statistically significant, (2) statistically significant static stress drop changes are inversely related to injection rate fluctuations. Therefore, it is highly expected that static stress drop of seismic events is influenced by pore pressure in underground fluid injection conditions and depends on the effective normal stress and strength of the medium.

  8. Geological Results from Drilling in the Poihipi (Western) Sector of the Wairakei Geothermal Field, NZ

    SciTech Connect

    Bogie, I.; Lawless, J.V.; MacKenzie, K.M.

    1995-01-01

    Four wells drilled into the Poihipi Sector on the Western margin of the Wairakei geothermal field have found a similar lithostratigraphy to that encountered in wells previously drilled in the general area. Young pumice breccias overly the Huka Falls Formation, with the latter containing intercalations of the Rautehuia Breccia. This in turn overlies ignimbrites and tuffaceous sediments of the Waiora Formation, which contains flows of Haparangi Rhyolite. This sequence is cut by steeply dipping normal faults which strike to the northeast and for the most part dip towards the northwest. Hydrothermal alteration is virtually limited to the Waiora and Haparangi units where a sequence of interlayered illite-smectite and illite clays are found along with chlorite, quartz, pyrite and calcite. There is a minor occurrence of zeolites. Despite large changes in the area's hydrology in response to exploitation, changes in alteration are limited to a comparatively deep occurrence of kaolinite and minor overprinting of epidote by illitic clay.

  9. Analysis of field-performance data on shell-and-tube heat exchangers in geothermal service

    SciTech Connect

    Silvester, L.F.; Doyle, P.T.

    1982-03-01

    Analysis of field performance data from a binary cycle test loop using geothermal brine and a hydrocarbon working fluid is reported. Results include test loop operational problems, and shell-and-tube heat exchanger performance factors such as overall heat transfer coefficients, film coefficients, pinch points, and pressure drops. Performance factors are for six primary heaters having brine in the tubes and hydrocarbon in the shells in counterflow, and for a condenser having cooling water in the tubes and hydrocarbon in the shell. Working fluids reported are isobutane, 90/10 isobutane/isopentane, and 80/20 isobutane/isopentane. Performance factors are for heating each working fluid at supercritical conditions in the vicinity of their critical pressure and temperature and condensing the same fluid.

  10. Downhole seismic monitoring of an acid treatment in the Beowawe Geothermal Field

    SciTech Connect

    Batra, R.; Albright, J.N.; Bradley, C.

    1984-01-01

    During the acid treatment of a subeconomic well at the Beowawe Geothermal Field, numerous seismic events were detected of which 22 could be located. The events occurred following a first stage of the acid treatment and generally define a trend paralleling the surface trace of the Malpais fault. No seismic signals were detected following a second stage of the acid treatment, despite the injection of almost twice as much additional fluid. It is postulated that the cause of seismic events following the first stage was due to shear failure of chemically weakened cemented fracturs or joints in the reservoir. Presumably reservoir strain was sufficiently reduced to preclude further rock failure during the second day of treatment.

  11. Modelling of chemical and thermal changes in well PN-26 Palinpinon geothermal field, Philippines

    SciTech Connect

    Malate, R.C.M.; O'Sullivan, M.J. )

    1991-01-01

    Significant changes in temperature, chloride and silica concentration have occurred in well PN-26 of the Palinpinon Geothermal Field as a result of reinjection fluid returning. The chloride changes are modelled by a simple time-dependent production - reinjection lumped parameter model. Analytic solutions are derived for both constant and variable production rates. The decline in measured wellbore temperature is then modelled by coupling the chloride mass balance model to a fracture flow model. Production silica changes are also modelled by coupling the silica mass balance model for the production area to a transport and deposition model for the fractured zone. The final model in this paper is able to match changes in chloride, temperature and silica.

  12. Seismic reflection survey in the geothermal field of the Rotorua Caldera, New Zealand

    SciTech Connect

    Lamarche, G. )

    1992-04-01

    This paper discusses a seismic reflection survey conducted in the southern part of the Rotorua geothermal field (New Zealand). Geological structures were interpreted along the two profiles to a depth of about 300 m. A seismic image of the Mamaku Ignimbrite is obtained and appears to show normal faulting. Depth of the top of the Mamaku Ignimbrite corroborates data from boreholes. Thickness of the Ignimbrite sheet may reach 280 m near Rotorua City. It is suggested that the Rotorua caldera boundary is not a single fault but a fault zone consisting of at least 4 faults. The displacement on any one fault is no greater than 30 m. The near surface cold-warm thermal boundary, at the northern boundary of the Whakarewarewa thermal area, is also shown in the seismic section.

  13. Reservoir-scale fracture permeability in the Dixie Valley, Nevada, geothermal field

    SciTech Connect

    Barton, C.A.; Zoback, M.D.; Hickman, S.; Morin, R.; Benoit, D.

    1998-08-01

    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.

  14. Pressure changes and their effects on the Cerro Prieto geothermal field

    SciTech Connect

    Bermejo M, F.J.; Navarro O, F.X.; Esquer P, C.A.; Castillo B, F.; de la Cruz D, F.C.

    1981-01-01

    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.

  15. The structural architecture of the Los Humeros volcanic complex and geothermal field, Trans-Mexican Volcanic Belt, Central Mexico

    NASA Astrophysics Data System (ADS)

    Norini, Gianluca; Groppelli, Gianluca; Sulpizio, Roberto; Carrasco Núñez, Gerardo; Davila Harris, Pablo

    2014-05-01

    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

  16. Influence of shallow flow on the deep geothermal field of Berlin - Results from 3D models

    NASA Astrophysics Data System (ADS)

    Frick, Maximilian; Sippel, Judith; Scheck-Wenderoth, Magdalena; Cacace, Mauro; Hassanzadegan, Alireza

    2015-04-01

    The goal of this study is to quantify the influence of fluid-driven heat transport on the subsurface temperature distribution of the city of Berlin, Germany. Berlin is located in the Northeast German Basin filled with several kilometers of sediments. Two of the clastic sedimentary units, namely the Middle Buntsandstein and the Sedimentary Rotliegend are of particular interest for geothermal exploration. Previous studies in the Northeast German Basin have already shown that subsurface temperature distributions are highly dependent on the geometries and properties of the geological units. Our work benefits strongly from these studies that involve numerical modeling of coupled conductive and convective heat transport. We follow a two-step approach where we first improve an existing structural model by integrating newly available 57 geological cross-sections, well data and deep seismics (down to ~4 km). Secondly, we perform a sensitivity analysis in which we investigate the effects of varying physical fluid and rock properties as well as hydraulic and thermal boundary conditions on the resulting temperature configuration. Computed temperatures are validated via comparison with existing well temperature measurements in the area. Of special interest for this study is the influence of the shallow aquifer systems on the subsurface temperature field. The major constituents of this system are the Quaternary silts and sands, the Tertiary Rupelian clay and the Tertiary sands beneath the Rupelian. These units have different hydraulic properties. The Rupelian clay represents a major aquitard in this respect hydraulically disconnecting the pre- and post-Rupelian succession. This aquitard shows a heterogeneous thickness distribution locally characterized by different hydrogeological windows (i.e. domains of no thickness) enabling intra-aquifer groundwater circulation at depth thus having a first-order effect on the shallow thermal field. As result of the simulations, we present

  17. Group II Xenoliths from Lunar Crater Volcanic Field, Central Nevada: Evidence for a Kinked Geotherm

    NASA Astrophysics Data System (ADS)

    Roden, M.; Mosely, J.; Norris, J.

    2015-12-01

    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.

  18. Geothermal Energy.

    ERIC Educational Resources Information Center

    Eaton, William W.

    Described are the origin and nature of geothermal energy. Included is the history of its development as an energy source, technological considerations affecting its development as an energy source, its environmental effects, economic considerations, and future prospects of development in this field. Basic system diagrams of the operation of a…

  19. Geothermal Energy.

    ERIC Educational Resources Information Center

    Eaton, William W.

    Described are the origin and nature of geothermal energy. Included is the history of its development as an energy source, technological considerations affecting its development as an energy source, its environmental effects, economic considerations, and future prospects of development in this field. Basic system diagrams of the operation of a…

  20. Impact of fluid injection on fracture reactivation at The Geysers geothermal field

    NASA Astrophysics Data System (ADS)

    Martínez-Garzón, Patricia; Kwiatek, Grzegorz; Bohnhoff, Marco; Dresen, Georg

    2016-10-01

    We analyze the spatiotemporal distribution of fault geometries from seismicity induced by fluid injection at The Geysers geothermal field. The consistency of these faults with the local stress field is investigated using (1) the fault instability coefficient I comparing the orientation of a fault with the optimal orientation for failure in the assumed stress field and (2) the misfit angle β between slip vectors observed from focal mechanisms and predicted from stress tensor. A statistical approach is applied to calculate the most likely fault instabilities considering the uncertainties from focal mechanisms and stress inversion. We find that faults activated by fluid injection may display a broad range in orientations. About 72% of the analyzed seismicity occurs on faults with favorable orientation for failure with respect to the stress field. However, a number of events are observed either to occur on severely misoriented faults or to slip in a different orientation than predicted from stress field. These events mostly occur during periods of high injection rates and are located in proximity to the injection wells. From the stress inversion, the friction coefficient providing the largest overall instability is μ = 0.5. About 91% of the events are activated with an estimated excess pore pressure <10 MPa, in agreement with previous models considering the combined effect of thermal and poroelastic stress changes from fluid injection. Furthermore, high seismic activity and largest magnitudes occur on favorably oriented faults with large instability coefficients and low slip misfit angles.

  1. Helium isotope study of geothermal features in Chile with field and laboratory data

    DOE Data Explorer

    Dobson, Patrick

    2013-02-11

    Helium isotope and stable isotope data from the El Tatio, Tinginguirica, Chillan, and Tolhuaca geothermal systems, Chile. Data from this submission are discussed in: Dobson, P.F., Kennedy, B.M., Reich, M., Sanchez, P., and Morata, D. (2013) Effects of volcanism, crustal thickness, and large scale faulting on the He isotope signatures of geothermal systems in Chile. Proceedings, 38th Workshop on Geothermal Reservoir Engineering, Stanford University, Feb. 11-13, 2013

  2. Assessing Past Fracture Connectivity in Geothermal Reservoirs Using Clumped Isotopes: Proof of Concept in the Blue Mountain Geothermal Field, Nevada USA

    NASA Astrophysics Data System (ADS)

    Huntington, K. W.; Sumner, K. K.; Camp, E. R.; Cladouhos, T. T.; Uddenberg, M.; Swyer, M.; Garrison, G. H.

    2015-12-01

    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

  3. Fluid circulation and reservoir conditions of the Los Humeros Geothermal Field (LHGF), Mexico, as revealed by a noble gas survey

    NASA Astrophysics Data System (ADS)

    Pinti, Daniele L.; Castro, M. Clara; Lopez-Hernandez, Aida; Han, Guolei; Shouakar-Stash, Orfan; Hall, Chris M.; Ramírez-Montes, Miguel

    2017-03-01

    Los Humeros Geothermal Field (LHGF) is one of four geothermal fields currently operating in Mexico, in exploitation since 1990. Located in a caldera complex filled with very low-permeability rhyolitic ignimbrites that are the reservoir cap-rock, recharge of the geothermal field is both limited and localized. Because of this, planning of any future geothermal exploitation must be based on a clear understanding of the fluid circulation. To this end, a first noble gas survey was carried out in which twenty-two production wells were sampled for He, Ne, Ar, Kr, and Xe isotope analysis. Air-corrected 3He/4He ratios (Rc) measured in the fluid, normalized to the helium atmospheric ratio (Ra; 1.384 × 10- 6), are consistently high across the field, with an average value of 7.03 ± 0.40 Ra. This value is close to that of the sub-continental upper mantle, indicating that LHGF mines heat from an active magmatic system. Freshwater recharge does not significantly affect He isotopic ratios, contributing 1-10% of the total fluid amount. The presence of radiogenic 40Ar* in the fluid suggests a fossil fluid component that might have circulated within the metacarbonate basement with radiogenic argon produced from detrital dispersed illite. Solubility-driven elemental fractionation of Ne/Ar, Kr/Ar, and Xe/Ar confirm extreme boiling in the reservoir. However, a combined analysis of these ratios with 40Ar/36Ar reveals mixing with an air component, possibly introduced by re-injected geothermal fluids.

  4. The geothermal field of Denmark from borehole measurements and 3D numerical modelling

    NASA Astrophysics Data System (ADS)

    Fuchs, Sven; Balling, Niels

    2017-04-01

    We present a 3D numerical crustal temperature model and analyze the present-day geothermal field of onshore Denmark, including parts of the Danish Basin, the northernmost part of the North German Basin and the Sorgenfrei-Tornquist Zone. An extensive analysis of borehole and well-log data on a basin scale is conducted to derive the model parameterization with a spatial distribution of rock thermal conductivity as well as new, regionally variable heat-flow values. A new structural geological model with lithological layers is provided by the Geological Survey of Denmark and Greenland (GEUS). Measured heat flow and borehole temperature observations (102 values from 47 wells) are used to constrain the modelling results in terms of calibration and validation. The prediction uncertainties between modelled and observed temperatures at deep borehole sites are small (rms = 1.3°C). For 22 deep boreholes, new values of terrestrial surface heat flow are derived ranging between 64 and 84 mW/m2 (mean of 77 ± 5 mW/m2) for the Danish Basin, between 60 and 95 mW/m2 (mean of 80 ± 10 mW/m2) for the very northern part of North German Basin, and between 63 and 66 mW/m2 (mean of 65 ± 2 mW/m2) in the Sorgenfrei-Tornquist Zone, respectively. Heat flow from the mantle is estimated to be between 31 and 39 mW/m2 (q1-q3; mean of 34 ± 7 mW/m2). Lateral temperature variations found by 3D modelling are caused by complex geological structures, like salt structures, lateral variations in the thickness of basin sediments or tectonic features. The variations in rock thermal conductivity associated with different lithological units generate significant variations in temperature gradients and heat flow. Major geothermal sandstone reservoirs show significantly different temperatures according to a large variation in reservoir depth and different thermal conductivity of overlying lithologies. For example, temperatures of the Gassum Formation, covering most of the Danish onshore areas, are within the

  5. Field based geothermal exploration: Structural controls in the Tarutung Basin/North Central Sumatra (Indonesia)

    NASA Astrophysics Data System (ADS)

    Nukman, M.; Moeck, I.

    2012-04-01

    The Tarutung Basin is one of several basins along the prominent Sumatra Fault System (SFS) which represents a dextral strike slip fault zone segmented into individual fault strands. The basins are located at right-stepping transfer. The Tarutung Basin hosts geothermal manifestations such as hot springs and travertines indicating a geothermal system with some decent potential in the subsurface. As part of geothermal exploration, field geology is investigated focusing on how the structural setting controls the thermal manifestation distribution. A complex fault pattern is now newly mapped and evidences sinistral faults striking E-W (Silangkitang), normal faults striking SE-NW at the eastern strand of Tarutung Basin (Sitompul) and normal faults striking NW-SE at the western strand of the basin (Sitaka). These structures form an angle greater than 450 with respect to the current maximum principal stress which is oriented in N-S. Secondary sinistral shear fractures identified as antithetic Riedel shears can be correlated with hot spring locations at Silangkitang, forming an angle of 500 with respect to the current maximum stress. A large angle of normal fault and antithetic Riedel shear trend with respect to the current maximum stress direction indicates that the structures have been rotated. Unidentified dextral strike slip faults might exist at the eastern strand of Tarutung Basin to accommodate the clockwise rotation between the eastern boundary of the basin and the NW-SE striking normal fault of Panabungan. Normal faults striking parallel with the SFS East of the basin are interpreted as dilatational jogs caused by the clockwise rotated block movement with respect to the NW-SE fault trend sinistral shear along ENE-WSW faults. Silicified pryroclastics in association with large discharge at hot springs at these NW-SE striking normal faults support this hypothesis. As proposed by Nivinkovich (1976) and Nishimura (1986) Sumatra has rotated 20° clockwise since the last

  6. Three-dimensional magnetotelluric exploration of Tenerife geothermal field (Canary Islands, Spain).

    NASA Astrophysics Data System (ADS)

    Piña-Varas, Perla; Ledo, Juanjo; Queralt, Pilar; Marcuello, Alex; Bellmunt, Fabián; Hidalgo, Raúl

    2013-04-01

    Several magnetotelluric (MT) surveys have been carried out to investigate the geothermal system in Tenerife Island (Canary Islands, Spain). These data have been acquired since 1987 till 2012 by different agencies and institutions. In 1987 and 1991, two MT surveys were carried out by the Spanish Geological Survey (IGME). These data in paper format (129 MT sites in total) were collected and digitized. In October 2009, 83 stations were acquired for Petratherm Ltd., and 25 stations in March 2012 by the University of Barcelona. In total, 237 MT stations distributed around the island center are available for this study. A simplified conceptual model of the island using known geological and geophysical data has been created to identify the ocean and topography effects on the MT data. The typical conceptual model of a generic high temperature volcanic geothermal system (Cumming, 2009a; Pellerin, 1996) and the 1D models from the MT data have played a key role for the correct construction of this conceptual model. Synthetic forward modeling was performed on a set of models to determine the effect of topography and of the conductive Atlantic Ocean. Finally, a 3D resistivity model of Tenerife Island has been computed with modEM code (Egbert and Kelbert, 2012). Out of the 237 MT sites available, 87 stations were discarded because of computational capability problems. Thus, for this new 3D model, 150 MT sites have been taking into account from the different field surveys. The model is discrtized on 94x65x133-layer grid and the inversions are undertaken using the off-diagonal components (Zxy, Zyx) of the impedance tensor for 16 periods in the frequency range from 1000 to 0.1 Hz. In the inversion processing we assumed a 5% error floor in the impedance components and the final RMS is 3.5. The 3D inversion model shows the typical layered pattern expected from a volcanic complex (andesite, basalt) with a possible geothermal overprint; a resistive fresh volcanic structure near the

  7. Temporal changes of static stress drop as a proxy for poroelastic effects at The Geysers geothermal field, California

    NASA Astrophysics Data System (ADS)

    Staszek, Monika; Orlecka-Sikora, Beata; Lasocki, Stanislaw; Kwiatek, Grzegorz; Leptokaropoulos, Konstantinos; Martinez-Garzon, Patricia

    2017-04-01

    One of the major environmental impacts of shale gas exploitation is triggered and induced seismicity. Due to the similarity of fluid injection process data from geothermal fields can be used as a proxy for shale gas exploitation associated seismicity. Therefore, in this paper we utilize 'The Geysers' dataset compiled within SHale gas Exploration and Exploitation induced Risks (SHEER) project. The dependence of earthquake static stress drops on pore pressure in the medium was previously suggested by Goertz-Allmann et al. (2011), who observed an increase of the static stress drop with the distance from injection well during reservoir stimulation at Deep Heat Mining project in Basel, Switzerland. Similar observation has been done by Kwiatek et al. (2014) in Berlín geothermal field, El Salvador. In this study, we use a high-quality data from The Geysers geothermal field to determine whether the static stress drops and the stress drop distributions change statistically significantly in time or not, and how such changes are correlated with the values of hypocenter depth, water injection rate, and distance from injection well. For the analyses we use a group of 354 earthquakes, which occurred in the proximity of Prati-9 and Prati-29 injection wells. Spectral parameters of these earthquakes were determined using mesh spectral ratio technique. Our results indicate that: (1) the static stress drop variation in time is statistically significant, (2) median static stress drop is inversely related to median injection rate. Therefore, it is highly expected that static stress drop is influenced by pore pressure in underground fluid injection conditions. References: Goertz-Allmann B., Goertz A., Wiemer S. (2011), Stress drop variations of induced earthquakes at the Basel geothermal site. Geophysical Research Letters, 38, L09308, doi:10.1029/2011GL047498. Kwiatek G., Bulut F., Bohnhoff M., Dresen G. (2014), High-resolution analysis of seismicity induced at Berlin geothermal field

  8. Thermal and petrologic constraints on lower crustal melt accumulation under the Salton Sea Geothermal Field

    NASA Astrophysics Data System (ADS)

    Karakas, Ozge; Dufek, Josef; Mangan, Margaret T.; Wright, Heather M.; Bachmann, Olivier

    2017-06-01

    In the Salton Sea region of southern California (USA), concurrent magmatism, extension, subsidence, and sedimentation over the past 0.5 to 1.0 Ma have led to the creation of the Salton Sea Geothermal Field (SSGF)-the second largest and hottest geothermal system in the continental United States-and the small-volume rhyolite eruptions that created the Salton Buttes. In this study, we determine the flux of mantle-derived basaltic magma that would be required to produce the elevated average heat flow and sustain the magmatic roots of rhyolite volcanism observed at the surface of the Salton Sea region. We use a 2D thermal model to show that a lower-crustal, partially molten mush containing < 20- 40% interstitial melt develops over a ∼105-yr timescale for basalt fluxes of 0.008 to 0.010 m3 /m2 /yr (∼0.0008 to ∼0.001 km3/yr injection rate) given extension rates at or below the current value of ∼0.01 m/yr (Brothers et al., 2009). These regions of partial melt are a natural consequence of a thermal regime that scales with average surface heat flow in the Salton Trough, and are consistent with seismic observations. Our results indicate limited melting and assimilation of pre-existing rocks in the lower crust. Instead, we find that basalt fractionation in the lower crust produces derivative melts of andesitic to dacitic composition. Such melts are then expected to ascend and accumulate in the upper crust, where they further evolve to give rise to small-volume rhyolite eruptions (Salton Buttes) and fuel local spikes in surface heat flux as currently seen in the SSGF. Such upper crustal magma evolution, with limited assimilation of hydrothermally altered material, is required to explain the slight decrease in δ18 O values of zircons (and melts) that have been measured in these rhyolites.

  9. Fracture permeability in the Matalibong-25 corehole, Tiwi geothermal field, Philippines

    SciTech Connect

    Nielson, Dennis L.; Clemente, Wilson C.; Moore, Joseph N.; Powell, Thomas S.

    1996-01-24

    The Tiwi geothermal field is located in southern Luzon on the northeast flank of Mt. Malinao, an andesitic volcano that was active 0.5 to 0.06 Ma. Matalibong-25 (Mat-25) was drilled through the Tiwi reservoir to investigate lithologic and fracture controls on reservoir permeability and to monitor reservoir pressure. Continuous core was collected from 2586.5 to 8000 feet (789 to 2439 meters) with greater than 95% recovery. The reservoir rocks observed in Mat-25 consist mainly of andesitic and basaltic lavas and volcaniclastic rocks above 6600 feet depth (2012 meters) and andesitic sediments below, with a transition from subaerial to subaqueous (marine) deposition at 5250 feet (1601 meters). The rocks in the reservoir interval are strongly altered and veined. Common secondary minerals include chlorite, illite, quartz, calcite, pyrite, epidote, anhydrite, adularia and wairakite. An 39Ar/40Ar age obtained on adularia from a quartz-adularia-cemented breccia at a depth of 6066 feet (2012 meters) indicates that the hydrothermal system has been active for at least 320,000 years. Fractures observed in the core were classified as either veins (sealed) or open fractures, with the latter assumed to represent fluid entries in the geothermal system. Since the core was not oriented, only fracture frequency and dip angle with respect to the core axis could be determined. The veins and open fractures are predominantly steeply dipping and have a measured density of up to 0.79 per foot in the vertical well. Below 6500 feet (1982 meters) there is a decrease in fracture intensity and in fluid inclusion temperatures.

  10. Fracture permeability in the Matalibong-25 corehole, Tiwi geothermal field, Philippines

    SciTech Connect

    Nielson, D.L.; Moore, J.N.; Clemente, W.C.

    1996-12-31

    The Tiwi geothermal field is located in southern Luzon on the northeast flank of Mt. Malinao, an andesitic volcano that was active 0.5 to 0.06 Ma. Matalibong-25 (Mat-25) was drilled through the Tiwi reservoir to investigate lithologic and fracture controls on reservoir permeability and to monitor reservoir pressure. Continuous core was collected from 2586.5 to 8000 feet (789 to 2439 meters) with greater than 95% recovery. The reservoir rocks observed in Mat-25 consist mainly of andesitic and basaltic lavas and volcaniclastic rocks above 6600 feet depth (2012 meters) and andesitic sediments below, with a transition from subaerial to subaqueous (marine) deposition at 5250 feet (1601 meters). The rocks in the reservoir interval are strongly altered and veined. Common secondary minerals include chlorite, illite, quartz, calcite rite, epidote, anhydrite, adularia and wairakite. An {sup 39}Ar/{sup 40}Ar age obtained on adularia from a quartz-adularia-cemented breccia at a depth of 6066 feet (2012 meters) indicates that the hydrothermal system has been active for at least 320,000 years. Fractures observed in the core were classified as either veins (sealed) or open fractures, with the latter assumed to represent fluid entries in the geothermal system. Since the core was not oriented, only fracture frequency and dip angle with respect to the core axis could be determined. The veins and open fractures are predominantly steeply dipping and have a measured density of up to 0.79 per foot in the vertical well. Below 6500 feet (1982 meters) there is a decrease in fracture intensity and in fluid inclusion temperatures.

  11. Predicting thermal conductivity of rocks from the Los Azufres geothermal field, Mexico, from easily measurable properties

    SciTech Connect

    Garcia, Alfonso; Contreras, Enrique; Dominquez, Bernardo A.

    1988-01-01

    A correlation is developed to predict thermal conductivity of drill cores from the Los Azufres geothermal field. Only andesites are included as they are predominant. Thermal conductivity of geothermal rocks is in general scarce and its determination is not simple. Almost all published correlations were developed for sedimentary rocks. Typically, for igneous rocks, chemical or mineral analyses are used for estimating conductivity by using some type of additive rule. This requires specialized analytical techniques and the procedure may not be sufficiently accurate if, for instance, a chemical analysis is to be changed into a mineral analysis. Thus a simple and accurate estimation method would be useful for engineering purposes. The present correlation predicts thermal conductivity from a knowledge of bulk density and total porosity, properties which provide basic rock characterization and are easy to measure. They may be determined from drill cores or cuttings, and the procedures represent a real advantage given the cost and low availability of cores. The multivariate correlation proposed is a quadratic polynomial and represents a useful tool to estimate thermal conductivity of igneous rocks since data on this property is very limited. For porosities between 0% and 25%, thermal conductivity is estimated with a maximum deviation of 22% and a residual mean square deviation of 4.62E-3 n terms of the log{sub 10}(k{rho}{sub b}) variable. The data were determined as part of a project which includes physical, thermal and mechanical properties of drill cores from Los Azufres. For the correlation, sixteen determinations of thermal conductivity, bulk density and total porosity are included. The conductivity data represent the first determinations ever made on these rocks.

  12. Source mechanisms of microearthquakes at the Southeast Geysers geothermal field, California

    SciTech Connect

    Kirkpatrick, Ann; Peterson, John E., Jr.; Majer, Ernest L.

    1996-01-24

    Source mechanisms of 985 microearthquakes at the Southeast Geysers geothermal field, are investigated using a moment tensor formulation. P- and S-wave amplitude and polarity are utilized to estimate the full, second-order moment tensor, which is then decomposed into isotropic, double-couple, and compensated linear vector dipole components. The moment tensor principal axes are used to infer the directions of principal stress associated with the double-couple component of the source mechanism. Most of the events can be modeled as primarily double-couple; however, a small but significant isotropic component, which can be either positive or negative, is also needed to explain the observed waveforms. Events with positive isotropic components and events with negative isotropic components both occur in areas of steam extraction and in areas of fluid injection. Principal axes of moment tensors with negative isotropic components are aligned with the regional stress field, while those of moment tensors with positive isotropic components differ significantly from the regional stress field. This suggests that two differing inducing mechanisms are required: negative-type events involve local stress perturbations that are small compared to the regional stress, while positive-type events involve stress perturbations which locally dominate over the regional stress.

  13. Integrated geophysical imaging of the Aluto-Langano geothermal field (Ethiopia).

    NASA Astrophysics Data System (ADS)

    Rizzello, Daniele; Armadillo, Egidio; Verdoya, Massimo; Pasqua, Claudio; Kebede, Solomon; Mengiste, Andarge; Hailegiorgis, Getenesh; Abera, Fitsum; Mengesha, Kebede; Meqbel, Naser

    2017-04-01

    The Aluto-Langano geothermal system is located in the central part of the Main Ethiopian Rift, one of the world's most tectonically active areas, where continental rifting has been occurring since several Ma and has yielded widespread volcanism and enhanced geothermal gradient. The geothermal system is associated to the Mt Aluto Volcanic Complex, located along the eastern margin of the rift and related to the Wonji Fault Belt, constituted by Quaternary NNE-SSW en-echelon faults. These structures are younger than the NE-SW border faults of the central Main Ethiopian Rift and were originated by a stress field oblique to the rift direction. This peculiar tectonism yielded local intense rock fracturing that may favour the development of geothermal reservoirs. In this paper, we present the results of an integrated geophysical survey carried out in 2015 over an area of about 200 km2 covering the Mt Aluto Volcanic Complex. The geophysical campaign included 162 coincident magnetotelluric and time domain electromagnetic soundings, and 207 gravity stations, partially located in the sedimentary plain surrounding the volcanic complex. Three-dimensional inversion of the full MT static-corrected tensor and geomagnetic tipper was performed in the 338-0.001 Hz band. Gravity data processing comprised digital enhancement of the residual Bouguer anomaly and 2D-3D inverse modelling. The geophysical results were compared to direct observations of stratigraphy, rock alteration and temperature available from the several deep wells drilled in the area. The magnetotelluric results imaged a low-resistivity layer which appears well correlated with the mixed alteration layer found in the wells and can be interpreted as a low-temperature clay cap. The clay-cap bottom depth is well corresponds to a change of thermal gradient. The clay cap is discontinuous, and in the central area of the volcanic complex is characterised by a dome-shape structure likely related to isotherm rising. The propilitic

  14. Recover Act. Verification of Geothermal Tracer Methods in Highly Constrained Field Experiments

    SciTech Connect

    Becker, Matthew W.

    2014-05-16

    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

  15. Geodetic measurements and numerical models of deformation at the Svartsengi Geothermal Field, Iceland, 1992 - 2010

    NASA Astrophysics Data System (ADS)

    Feigl, K.; Ali, T.; Wang, H. F.; Fridleifsson, G. O.; Sigurdsson, O.; Sigmundsson, F.

    2012-12-01

    To study rheology — the constitutive relations between stress and strain— we apply a known impulse to a mechanical system and then measure the subsequent response. For example, by ringing a bell and listening to the resulting sound, we can infer that the material in the bell behaves as an elastic solid with little attenuation. By modeling the impulse (stress) and measuring the response (strain), and defining the constitutive relations between the two, we can make inferences about the underlying physical processes. In the case of the earth, the response is crustal deformation that can be measured using interferometric synthetic aperture radar (InSAR). Such experiments are feasible where industrial extraction of oil, gas, water, or heat causes subsidence, provided that data are available to describe both the impulse and the response. The Svartsengi geothermal field meets the requirements for a rheological experiment. Located on the Reykjanes Peninsula in Iceland, it is associated with a segment of mid-ocean ridge of the same name. The operators of the Svartsengi field have monitored the water level, borehole pressure and surface deformation since beginning production in 1976. In this study, we analyze radar images acquired on 78 distinct dates between 1992 and 2010 by six satellite missions: ERS-1, ERS-2, Envisat, ALOS, TerraSAR-X, and TanDEM-X. As in previous studies (Vadon and Sigmundsson, 1997, Keiding et al., 2010), the InSAR results indicate subsidence at the order of several centimeters per year over an area roughly five kilometers in radius. To describe this deformation, one can consider a simple model that assumes a half space with uniform elastic properties. For a reservoir shaped like a prolate spheroid, the model parameters include depth, length of the semi-major axis, width of the semi-minor axis, strike of the spheroid axis, plunge of the spheroid axis, and a pressure change (Yang et al., 1988). This model has been applied to the Coso geothermal

  16. Comments on: The structure of the shallow crust beneath Olkaria geothermal field, Kenya, deduced from gravity studies, by J.M. Ndombi

    NASA Astrophysics Data System (ADS)

    Hochstein, M. P.

    1984-04-01

    Major geothermal systems in the Kenya Rift Valley are located over, or near to, elongated axial gravity highs. A recently published interpretative model, which explains the axial gravity high over the Olkaria geothermal field in terms of shallow dyke intrusions, is not acceptable. This conclusion is corroborated by density measurements on surface samples and cores from production bores in the Olkaria field. Elongated, high-standing mafic intrusions are the likely source of the axial gravity highs in the rift valley. These intrusions appear to be the heat source for most geothermal systems in the rift.

  17. Remote triggering and numerical simulations of passing seismic waves at the Larderello-Travale Geothermal Field, Italy

    NASA Astrophysics Data System (ADS)

    Fuchs, Florian; Lupi, Matteo; Saenger, Erik

    2017-04-01

    Seismic waves generated by large magnitude earthquakes can affect geological systems located thousands of kilometers far from the epicenter. The Larderello-Travale geothermal field is one of the most studied high-enthalpy geothermal systems worldwide shown to be sensitive to incoming seismic energy. In this study we detected local seismic activity at the Larderello-Travale field, coinciding with the passage of Rayleigh waves released by the 2011 M9.0 Tohoku earthquake. The earthquakes of local magnitudes 1.6 and 1.7 occurred at 6 km and 8 km depth, respectively. We suggest that these earthquakes were dynamically triggered by transient Rayleigh waves which induced a maximum vertical displacement of approximately 7.5 mm at the hydrothermal field (for waves with period of 200 s). We estimate a dynamic stress of about 8 kPa for a measured peak ground velocity of 0.8 mm/s and propose that this additional stress in a clock-advance process triggered the local earthquakes which may have eventually occurred naturally at a later time. Previous studies also report increased seismic activity at the Larderello-Travale geothermal field after regional earthquakes. We conducted numerical simulations of P-, S-, Love and Rayleigh waves propagating through a detailed model of the Larderello-Travale geothermal field based on the known velocity structure. This enables us to identify potential regions where seismic energy may accumulate due to local structure. Results indicate that maximum displacements focus differently when considering body or surface waves. We identify a region located at 3-5 km depth (k-horizon) that may correspond to the brittle-ductile boundary where almost no seismic energy is focused.

  18. Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

    USGS Publications Warehouse

    Nordstrom, D. Kirk; Guo, Qinghai; McCleskey, R. Blaine

    2014-01-01

    Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1–2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.

  19. Response of the Los Azufres Geothermal Field to Four Years of 25 MW Wellhead Generation

    SciTech Connect

    Kruger, P.; Ortiz, J.; Miranda, G.; Gallardo, M.

    1987-01-20

    Production and chemical data have been compiled and analyzed on a six-month averaged basis for the first four years of electric energy generation with five 5-MW wellhead generators at the Los Azufres geothermal field. The data were evaluated with respect to the extent of observable thermal drawdown of the reservoir from 25 MW of generation in relation to the estimated capacity of the field of several hundred megawatts of power. The analysis updates the previous one compiled after the first two years of continuous production, at which time the results indicated that differences in reservoir temperature estimated from geochemical thermometers and wellhead production data were not statistically significant based on the number of data and the standard deviations. Analysis of the data after four years of operation were made for the larger number of data and smaller standard deviations. The results review the adequacy of the sampling frequency and the reliability of the measurements from statistical t-Test of the means of the first and second two-year periods. 3 figs., 5 tabs., 20 refs.

  20. Preliminary Gas and Isotope Geochemistry in the Rehai Geothermal Field, P.R. China

    SciTech Connect

    P., Zhao; Z., Liao

    1995-01-01

    Based on gas and sulphur isotopic composition, two types of steam in Rehai geothermal field are identified. One is with higher CO{sub 2} and H{sub 2}S concentration, the {delta}{sup 34}S of H{sub 2}S is in the range 2.49{per_thousand} to -1.04{per_thousand} (vs CDT), from which the H{sub 2}S-temperature is over than 250 C. The other is with lower CO{sub 2} and H{sub 2}S concentration, the {delta}{sup 34}S of H{sub 2}S is in the range -4.0{per_thousand} to -8.36{per_thousand}, from which the H{sub 2}S- and H{sub 2}-temperatures are 180 C-210 C, in good agreement with quartz temperature. The thermal water in the Rehai field is of local meteoric origin. Maximum {delta}{sup 18}O-value shift is less than 2.0{per_thousand} (vs SMOW). Mixing is widespread and could be identified on isotope and solute chemistry.

  1. Carbon isotope geochemistry of hydrocarbons in the Cerro Prieto geothermal field, Baja California Norte, Mexico

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.; Stallard, M. L.; Nehring, N. L.; Truesdell, A. H.

    1988-01-01

    Hydrocarbon abundances and stable-isotopic compositions were measured in wells M5, M26, M35 and M102, which represent a range of depths (1270-2000 m) and temperatures (275-330 degrees C) in the field. In order to simulate the production of the geothermal hydrocarbons, gases were collected from the pyrolysis of lignite in the laboratory. This lignite was obtained from a well which sampled rock strata which are identical to those occurring in the field, but which have experienced much lower subsurface temperatures. In both the well and the laboratory observations, high-temperature environments favored higher relative concentrations of methane, ethane and benzene and generally higher delta 13C-values in the individual hydrocarbons. The best correlation between the laboratory and well data is obtained when laboratory-produced gases from experiments conducted at lower (400 degrees C) and higher (600 degrees C) temperatures are mixed. This improved correlation suggests that the wells are sampling hydrocarbons produced from a spectrum of depths and temperatures in the sediments.

  2. East Olkaria Geothermal Field, Kenya: 1. History match with production and pressure decline data

    NASA Astrophysics Data System (ADS)

    Bodvarsson, Gudmundur S.; Pruess, Karsten; Stefansson, Valgardur; Bjornsson, Sveinbjorn; Ojiambo, Sebastian B.

    1987-01-01

    A detailed three-dimensional model of the present well field of the Olkaria geothermal field in Kenya (East Olkaria) has been developed. The model matches reasonably well flow rate and enthalpy data from all existing wells at East Olkaria. The history match shows that the effective permeabilities in the steam zone and the underlying liquid-dominated zone are 7.5 and 4.0 mdarcy, respectively. These values are somewhat higher than those inferred from well test data. The effective fracture porosity in the liquid-dominated zone is estimated to be 2% on the average, with spatial variations of 0.25-5%. The modeling studies suggest that the reservoir system is of rather uniform permeability and that no barriers to fluid flow are necessary to match the data. However, there appears to be a high permeability anomaly below a depth of 1000 m extending north-south through some of the more productive wells (wells 12, 15, 16, and 20).

  3. Carbon isotope geochemistry of hydrocarbons in the Cerro Prieto geothermal field, Baja California Norte, Mexico

    USGS Publications Warehouse

    Des Marais, D.J.; Stallard, M.L.; Nehring, N.L.; Truesdell, A.H.

    1988-01-01

    Hydrocarbon abundances and stable-isotopic compositions were measured in wells M5, M26, M35 and M102, which represent a range of depths (1270-2000 m) and temperatures (275-330??C) in the field. In order to simulate the production of the geothermal hydrocarbons, gases were collected from the pyrolysis of lignite in the laboratory. This lignite was obtained from a well which sampled rock strata which are identical to those occurring in the field, but which have experienced much lower subsurface temperatures. In both the well and the laboratory observations, high-temperature environments favored higher relative concentrations of methane, ethane and benzene and generally higher ??13C-values in the individual hydrocarbons. The best correlation between the laboratory and well data is obtained when laboratory-produced gases from experiments conducted at lower (400??C) and higher (600??C) temperatures are mixed. This improved correlation suggests that the wells are sampling hydrocarbons produced from a spectrum of depths and temperatures in the sediments. ?? 1988.

  4. Carbon isotope geochemistry of hydrocarbons in the Cerro Prieto geothermal field, Baja California Norte, Mexico

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.; Stallard, M. L.; Nehring, N. L.; Truesdell, A. H.

    1988-01-01

    Hydrocarbon abundances and stable-isotopic compositions were measured in wells M5, M26, M35 and M102, which represent a range of depths (1270-2000 m) and temperatures (275-330 degrees C) in the field. In order to simulate the production of the geothermal hydrocarbons, gases were collected from the pyrolysis of lignite in the laboratory. This lignite was obtained from a well which sampled rock strata which are identical to those occurring in the field, but which have experienced much lower subsurface temperatures. In both the well and the laboratory observations, high-temperature environments favored higher relative concentrations of methane, ethane and benzene and generally higher delta 13C-values in the individual hydrocarbons. The best correlation between the laboratory and well data is obtained when laboratory-produced gases from experiments conducted at lower (400 degrees C) and higher (600 degrees C) temperatures are mixed. This improved correlation suggests that the wells are sampling hydrocarbons produced from a spectrum of depths and temperatures in the sediments.

  5. Applications of gas chemistry in evaluating physical processes in the Southern Negros (Palinpinon) geothermal field, Philippines

    SciTech Connect

    D`Amore, F.; Nuti, S.; Ramos-Candelaria, M.N.; Seastres, J.S. Jr.; Ruaya, J.R.

    1993-10-01

    Three major physical processes have occurred in the Palinpinon geothermal system due to exploitation from 1985 to 1991. They were identified using gas compositions and equilibria involving H{sub 2}, H{sub 2}S, CH{sub 4} and CO{sub 2} to calculate temperature and vapor fraction in the reservoir. The first process is pressure drawdown in the southern part of the field, producing a local increase in the vapor fraction, with the liquid maintaining a high measured temperature, close to 300 C. The second process is vapor loss from an original liquid phase during its ascent through fractures. Wells affected by this process show high degrees of vapor loss (> 10%) when evaluated at the original high temperature of the liquid (290--300 C). But if vapor loss is modeled to occur at much lower temperatures (220--250 C), more realistic vapor losses (1--3%) are calculated. The last process involves mixing and cooling due to injection fluid returns to wells located in the northeastern part of the field. For some wells the fraction of injected brine in total temperatures can decline from 290 to 300 C to as low as 215--220 C, corresponding to periods when most of the produced fluids are derived from injected brine. Gas geothermometry gives a more reliable temperature estimate than quartz geothermometry for fluids with high fractions of injected brine, as the gas equilibria reflects the local reservoir temperature.

  6. A proven elastomer compound for extremely hostile geothermal and oil field environments

    SciTech Connect

    Hirasuna, A.R.; Friese, G.J.; Stephens, C.A.

    1983-02-01

    Since 1979 the Y267 EPDM elastomer has been independently tested by other organizations in a variety of field and laboratory applications. The following are some examples. The same Y267 EPDM O-rings worked with no leaks as logging tool seals for multiple trips to 4600M (15k ft.) at 320/sup 0/C (608F) BHST. A packer element performed flawlessly for five months in a 204/sup 0/C (400F) continuous steam injection well and was retrieved at the end of the test in an as-new condition. A high-pressure Y267 EPDM packer test was performed with complete success at 232/sup 0/C (450F) for a 7.5 day test in sour crude with differential pressures to 138 MPa (20 ksi) and the seal condition was only very slightly changed by the test. Comprehensive compatibility testing of 34 compounds from 15 companies in geothermal brine, isobutane, and oil at 191C-266/sup 0/C (375-510F) showed that the Y267 EPDM was best of the 34 in all three fluids. Over 15 laboratory and over 20 field case histories of Y267 EPDM such as the above examples are reported. All strongly establish that Y267 EPDM is at the cutting edge of technology.

  7. Salton Sea Geothermal Field, California, as a near-field natural analog of a radioactive waste repository in salt

    SciTech Connect

    Elders, W.A.; Cohen, L.H.

    1983-11-01

    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.

  8. Geothermal Prospecting using Hyperspectral Imaging and Field Observations, Dixie Meadows, NV

    SciTech Connect

    Kennedy-Bowdoin, T; Silver, E; Martini, B; Pickles, W

    2004-04-26

    In an ongoing project to relate surface hydrothermal alteration to structurally controlled geothermal aquifers, we mapped a 16 km swath of the eastern front of the Stillwater Range using Hyperspectral fault and mineral mapping techniques. The Dixie Valley Fault system produces a large fractured aquifer heating Pleistocene aged groundwater to a temperature of 285 C at 5-6 km. Periodically over the last several thousand years, seismic events have pushed these heated fluids to the surface, leaving a rich history of hydrothermal alteration in the Stillwater Mountains. At Dixie Hot Springs, the potentiometric surface of the aquifer intersects the surface, and 75 C waters flow into the valley. We find a high concentration of alunite, kaolinite, and dickite on the exposed fault surface directly adjacent to a series of active fumaroles on the range front fault. This assemblage of minerals implies interaction with water in excess of 200 C. Field spectra support the location of the high temperature mineralization. Fault mapping using a Digital Elevation Model in combination with mineral lineation and field studies shows that complex fault interactions in this region are improving permeability in the region leading to unconfined fluid flow to the surface. Seismic studies conducted 10 km to the south of Dixie Meadows show that the range front fault dips 25-30 to the southeast (Abbott et al., 2001). At Dixie Meadows, the fault dips 35 to the southeast, demonstrating that this region is part of the low angle normal fault system that produced the Dixie Valley Earthquake in 1954 (M=6.8). We conclude that this unusually low angle faulting may have been accommodated by the presence of heated fluids, increasing pore pressure within the fault zone. We also find that younger synthetic faulting is occurring at more typical high angles. In an effort to present these findings visually, we created a cross-section, illustrating our interpretation of the subsurface structure and the

  9. Pressure Profiles in Two-Phase Geothermal Wells: Comparison of Field Data and Model Calculations

    SciTech Connect

    Ambastha, A.K.; Gudmundsson, J.S.

    1986-01-21

    Increased confidence in the predictive power of two-phase correlations is a vital part of wellbore deliverability and deposition studies for geothermal wells. Previously, the Orkiszewski (1967) set of correlations has been recommended by many investigators to analyze geothermal wellbore performance. In this study, we use measured flowing pressure profile data from ten geothermal wells around the world, covering a wide range of flowrate, fluid enthalpy, wellhead pressure and well depth. We compare measured and calculated pressure profiles using the Orkiszewski (1967) correlations.

  10. Modeling of geothermal systems

    SciTech Connect

    Bodvarsson, G.S.; Pruess, K.; Lippmann, M.J.

    1985-03-01

    During the last decade the use of numerical modeling for geothermal resource evaluation has grown significantly, and new modeling approaches have been developed. In this paper we present a summary of the present status in numerical modeling of geothermal systems, emphasizing recent developments. Different modeling approaches are described and their applicability discussed. The various modeling tasks, including natural-state, exploitation, injection, multi-component and subsidence modeling, are illustrated with geothermal field examples. 99 refs., 14 figs.

  11. Geothermal Energy.

    ERIC Educational Resources Information Center

    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)…

  12. Physical properties of two core samples from Well 34-9RD2 at the Coso geothermal field, California

    USGS Publications Warehouse

    Morrow, C.A.; Lockner, D.A.

    2006-01-01

    The Coso geothermal field, located along the Eastern California Shear Zone, is composed of fractured granitic rocks above a shallow heat source. Temperatures exceed 640 ?F (~338 ?C) at a depth of less than 10000 feet (3 km). Permeability varies throughout the geothermal field due to the competing processes of alteration and mineral precipitation, acting to reduce the interconnectivity of faults and fractures, and the generation of new fractures through faulting and brecciation. Currently, several hot regions display very low permeability, not conducive to the efficient extraction of heat. Because high rates of seismicity in the field indicate that the area is highly stressed, enhanced permeability can be stimulated by increasing the fluid pressure at depth to induce faulting along the existing network of fractures. Such an Enhanced Geothermal System (EGS), planned for well 46A-19RD, would greatly facilitate the extraction of geothermal fluids from depth by increasing the extent and depth of the fracture network. In order to prepare for and interpret data from such a stimulation experiment, the physical properties and failure behavior of the target rocks must be fully understood. Various diorites and granodiorites are the predominant rock types in the target area of the well, which will be pressurized from 10000 feet measured depth (MD) (3048m MD) to the bottom of the well at 13,000 feet MD (3962 m MD). Because there are no core rocks currently available from well 46A-19RD, we report here on the results of compressive strength, frictional sliding behavior, and elastic measurements of a granodiorite and diorite from another well, 34-9RD2, at the Coso site. Rocks cored from well 34-9RD2 are the deepest samples to date available for testing, and are representative of rocks from the field in general.

  13. Three-dimensional numerical reservoir simulation of the EGS Demonstration Project at The Geysers geothermal field

    NASA Astrophysics Data System (ADS)

    Borgia, Andrea; Rutqvist, Jonny; Oldenburg, Curt M.; Hutchings, Lawrence; Garcia, Julio; Walters, Mark; Hartline, Craig; Jeanne, Pierre; Dobson, Patrick; Boyle, Katie

    2013-04-01

    The Enhanced Geothermal System (EGS) Demonstration Project, currently underway at the Northwest Geysers, California, aims to demonstrate the feasibility of stimulating a deep high-temperature reservoir (up to 400 °C) through water injection over a 2-year period. On October 6, 2011, injection of 25 l/s started from the Prati 32 well at a depth interval of 1850-2699 m below sea level. After a period of almost 2 months, the injection rate was raised to 63 l/s. The flow rate was then decreased to 44 l/s after an additional 3.5 months and maintained at 25 l/s up to August 20, 2012. Significant well-head pressure changes were recorded at Prati State 31 well, which is separated from Prati 32 by about 500 m at reservoir level. More subdued pressure increases occur at greater distances. The water injection caused induced seismicity in the reservoir in the vicinity of the well. Microseismic monitoring and interpretation shows that the cloud of seismic events is mainly located in the granitic intrusion below the injection zone, forming a cluster elongated SSE-NNW (azimuth 170°) that dips steeply to the west. In general, the magnitude of the events increases with depth and the hypocenter depth increases with time. This seismic cloud is hypothesized to correlate with enhanced permeability in the high-temperature reservoir and its variation with time. Based on the existing borehole data, we use the GMS™ GUI to construct a realistic three-dimensional (3D) geologic model of the Northwest Geysers geothermal field. This model includes, from the top down, a low permeability graywacke layer that forms the caprock for the reservoir, an isothermal steam zone (known as the normal temperature reservoir) within metagraywacke, a hornfels zone (where the high-temperature reservoir is located), and a felsite layer that is assumed to extend downward to the magmatic heat source. We then map this model onto a rectangular grid for use with the TOUGH2 multiphase, multicomponent, non

  14. Deformation near the Casa Diablo geothermal well field and related processes Long Valley caldera, Eastern California, 1993-2000

    USGS Publications Warehouse

    Howle, J.F.; Langbein, J.O.; Farrar, C.D.; Wilkinson, S.K.

    2003-01-01

    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

  15. Abrupt physical and chemical changes during 1992-1999, Anderson Springs, SE Geyser Geothermal Field, California

    USGS Publications Warehouse

    Janik, Cathy J.; Goff, Fraser; Walter, Stephen R.; Sorey, Michael L.; Counce, Dale; Colvard, Elizabeth M.

    2000-01-01

    The Anderson Springs area is located about 90 miles (145 kilometers) north of San Francisco, California, in the southwestern part of Lake County. The area was first developed in the late 1800s as a health resort, which was active until the 1930s. Patrons drank a variety of cool to hot mineral waters from improved springs, swam in various baths and pools, and hiked in the rugged hills flanking Anderson Creek and its tributaries. In the bluffs to the south of the resort were four small mercury mines of the eastern Mayacmas quicksilver district. About 1,260 flasks of mercury were produced from these mines between 1909 and 1943. By the early 1970s, the higher ridges south and west of Anderson Springs became part of the southeast sector of the greater Geysers geothermal field. Today, several electric power plants are built on these ridges, producing energy from a vapor-dominated 240 °C reservoir. Only the main hot spring at Anderson Springs has maintained a recognizable identity since the 1930s. The hot spring is actually a cluster of seeps and springs that issue from a small fault in a ravine southwest of Anderson Creek. Published and unpublished records show that the maximum temperature (Tm) of this cluster fell gradually from 63°C in 1889 to 48°C in 1992. However, Tm of the cluster climbed to 77°C in 1995 and neared boiling (98°C) in 1998. A new cluster of boiling vents and small fumaroles (Tm = 99.3°C) formed in 1998 about 30 m north of the old spring cluster. Several evergreen trees on steep slopes immediately above these vents apparently were killed by the new activity. Thermal waters at Anderson Hot Springs are mostly composed of near-surface ground waters with some added gases and condensed steam from The Geysers geothermal system. Compared to gas samples from Southeast Geysers wells, the hot spring gases are higher in CO2 and lower in H2S and NH3. As the springs increased in temperature, however, the gas composition became more like the mean composition

  16. Local and regional seismic response to injection and production at the Salton Sea geothermal field, southern California

    NASA Astrophysics Data System (ADS)

    Lajoie, L. J.; Brodsky, E. E.

    2011-12-01

    California hosts both the largest geothermal resource capacity and highest seismicity rate in the nation. With plans to increase geothermal output, and proven earthquake triggering in the vicinity of geothermal power plants worldwide, it is important to determine the local and regional effects of geothermal power production. This study focuses on relating the volume of fluid extracted from and re-injected into wells at the Salton Sea geothermal field (SSGF) in Southern California to local seismicity rate and increased probability of larger events on nearby faults such as the San Andreas and Imperial faults. Seismic data is obtained from the publicly available Advanced National Seismic System (ANSS) catalog and SSGF injection and production data from the State of California Department of Conservation. We identify triggered earthquakes in the catalog by modeling seismicity in a 15km radius around the SSGF according to an Epidemic-Type Aftershock Sequence (ETAS) method. The model seeks to fit the cumulative seismicity curve from our dataset by optimizing five seismic parameters in accordance with Gutenberg-Richter and Omori's law. The modeled curve is then removed from the dataset to isolate the non-ETAS, or production-triggered, signal. We then formulate a constitutive law to relate the seismicity rate to the driving stress (i.e. volumetric strain in the reservoir). Defining the local stressing rate provides a tool for predicting the effects that production has on regional seismicity rates. The largest spike in SSGF net production volume over the past 30 years is accompanied by the one of the largest increases in both seismicity rate and moment release within the geothermal field. This indicates a direct coupling between net fluid production volume (volume extracted minus volume re-injected) and seismicity rate and cumulative seismic moment in the field. Three dimensional plots of hypocentral earthquake locations show that seismicity is concentrated on an

  17. Extension of the Cerro Prieto field and zones in the Mexicali Valley with geothermal possibilities in the future

    SciTech Connect

    Fonseca L, H.L.; de la Pena L, A.; Puente C, I.; Diaz C, E.

    1981-01-01

    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.

  18. Hyperspectral image analysis for the determination of alteration minerals in geothermal fields: Çürüksu (Denizli) Graben, Turkey

    NASA Astrophysics Data System (ADS)

    Uygur, Merve; Karaman, Muhittin; Kumral, Mustafa

    2016-04-01

    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

  19. Modelling the Interaction of Multiple Borehole Heat Exchangers in Shallow Geothermal Fields

    NASA Astrophysics Data System (ADS)

    Shao, H.; Schelenz, S.; Kist, N.; Shim, B. O.; Bucher, A.; Kolditz, O.

    2014-12-01

    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

  20. Modeling study of the natural state of the Heber geothermal field, California

    SciTech Connect

    Lippmann, M.J.; Bodvarsson, G.S.

    1983-06-01

    As a first step in simulating the behavior of the Heber field under exploitation, the system is modeled in its natural (pre-exploitation) state. Using Lawrence Berkeley Laboratory's (LBL) computer code PT and a radially symmetric model, a reasonable match between published and calculated temperature and pressure distributions is obtained. The results of the study indicate that the Heber geothermal system is created by the upflow of hot water through a central zone of higher permeability. The model shows that in its natural state the system is recharged at depth by a 15 MW(thermal) convective heat source. The existence of a radially symmetric convection pattern, whose axis coincides with that of the Heber anomaly is suggested. At the lower part of the ascending hot water plume, the deep recharge water mixes with colder water moving laterally towards the axis of the system. On the upper part, the rising plume spreads radially outward before reaching the bottom of the caprock, at 550 m depth. The model results suggest that the caprock is quite permeable, with convection controlling the temperature distribution. The low permeability of the upper zones in the outer region of the system may be due to mineral precipitation.

  1. Galapagos Spreading Center at 86/sup 0/W: A detailed geothermal field study

    SciTech Connect

    Green, K.E.; Von Herzen, R.P.; Williams, D.L.

    1981-02-10

    We report here measurements of the heat flow field of the Galapagos Spreading Center on crust of age less than 1.0 m.y. The 443 measurements in an area of about 570 km/sup 2/ reveal the general planform of the geothermal flux and permit the first truly areal estimate of the near-axis conductive heat flux. The intrusion process and associated hydrothermal circulation dominate the surface heat flow pattern, with circulation apparently continuing beyond the limits of our survey. The areal average of the conductive heat flux is 7.1 +- 0.8 HFU (295 +- 33 mW/m/sup 2/), about one-third the heat flux predicted by plate models. The remaining heat is apparently removed by venting of hydrothermal waters at the spreading axis and through basalt outcrops and hydrothermal mounds off axis. The pattern of surface heat flux is lineated parallel to the axis and the strongly lineated topography. Sharp lateral gradients in the heat flow, greater than 10 HFU/km near escarpments and commonly expressed as high heat flow at the tops of the scarps and lower heat flow in the valleys, may indicate a local concentration of the circulation by surface fault systems and/or variable sediment thickness.

  2. The Galapagos Spreading Centre at 86o W: a detailed geothermal field study.

    USGS Publications Warehouse

    Green, K.E.; Von Herzen, R. P.; Williams, D.L.

    1981-01-01

    We report here measurements of the heat flow field of the Galapagos Spreading Center on crust of age less than 1.0 m.y. The 443 measurements in an area of about 570 km2 reveal the general planform of the geothermal flux and permit the first truly areal estimate of the near-axis conductive heat flux. The intrusion process and associated hydrothermal circulation dominate the surface heat flow pattern, with circulation apparently continuing beyong the limits of our survey. The areal average of the conductive heat flux is 7.1+-0.8 HFU (295+-33 m W/m2), about one-third the heat flux predicted by plate models. The remaining heat is apparently removed by venting of hydrothermal waters at the spreading axis and through basalt outcrops and hydrothermal mounds off axis. The pattern of surface heat flux is lineated parallel to the axis and the strongly lineated topography. Sharp lateral gradients in the heat flow, greater than 10 HFU/km near escarpments and commonly expressed as high heat flow at the tops of the scarps and lower heat flow in the valleys, may indicate a local concentration of the circulation by surface fault systems and/or variable sediment thickness. -Authors

  3. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal field, California, was measured at 150, 200, and 250 C as a function of steam pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption and desorption runs were made in order to investigate the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were made on the same rock samples. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there was no direct correlation between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The hysteresis decreased significantly at 250 C. The results indicate that multilayer adsorption, rather than capillary condensation, is the dominant water storage mechanism at high temperatures.

  4. Arsenic speciation in sinter mineralization from a hydrothermal channel of El Tatio geothermal field, Chile

    NASA Astrophysics Data System (ADS)

    Alsina, Marco A.; Zanella, Luciana; Hoel, Cathleen; Pizarro, Gonzalo E.; Gaillard, Jean-François; Pasten, Pablo A.

    2014-10-01

    El Tatio geothermal field is the principal natural source of arsenic for the Loa River, the main surface water resource in the hyper-arid Atacama Desert (Antofagasta Region, Northern Chile). Prior investigations by bulk X-ray absorption spectroscopy have identified hydrous ferric oxides as the principal arsenic-containing phase in sinter material from El Tatio, suggesting sorption as the main mechanism for arsenic scavenging by the solid phases of these hot spring environments. Here we examine siliceous sinter material sampled from a hydrothermal channel using synchrotron based X-ray micro-probe techniques, including As and Fe Kα X-ray fluorescence (μ-XRF), As K-edge X-ray absorption near edge structure (μ-XANES), and X-ray diffraction (μ-XRD). Least-squares linear fitting of μ-XANES spectra shows that arsenic is predominantly present as arsenate sorbed on hydrous ferric oxides (63% molar proportion), but we also identify nodular arsenide micro-mineralizations (37% molar proportion) similar to loellingite (FeAs2), not previously detected during bulk-scale analysis of the sinter material. Presence of arsenide mineralizations indicates development of anoxic environments on the surface of the siliceous sinter, and suggests a more complex biogeochemistry for arsenic than previously observed for circum-neutral pH brine hot spring environments.

  5. A GEOLOGICAL AND GEOPHYSICAL STUDY OF THE BACA GEOTHERMAL FIELD, VALLES CALDERA, NEW MEXICO

    SciTech Connect

    Wilt, M.; Haar, S.V.

    1982-03-01

    The Baca location {number_sign}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 500 F. Stratigraphically the reservoir region can be described as a five-layer sequence that includes (1) caldera fill and the upper units of the Bandelier ash flow tuff, (2) the lower members of this tuff, which comprise the main reservoir rock at Baca, (3) the Pliocene Paliza Canyon volcanics, (4) Tertiary sands and Paleozoic sedimentary rocks, and (5) Precambrian granitic basement. Production is 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. 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.

  6. The impact of temperature on microbial diversity and AOA activity in the Tengchong Geothermal Field, China.

    PubMed

    Li, Haizhou; Yang, Qunhui; Li, Jian; Gao, Hang; Li, Ping; Zhou, Huaiyang

    2015-11-26

    Using a culture-independent method that combines CARD-FISH, qPCR and 16S rDNA, we investigated the abundance, community structure and diversity of microbes along a steep thermal gradient (50-90 °C) in the Tengchong Geothermal Field. We found that Bacteria and Archaea abundance changed markedly with temperature changes and that the number of cells was lowest at high temperatures (90.8 °C). Under low-temperature conditions (52.3-74.6 °C), the microbial communities were dominated by Bacteria, which accounted for 60-80% of the total number of cells. At 74.6 °C, Archaea were dominant, and at 90.8 °C, they accounted for more than 90% of the total number of cells. Additionally, the microbial communities at high temperatures (74.6-90.8 °C) were substantially simpler than those at the low-temperature sites. Only a few genera (e.g., bacterial Caldisericum, Thermotoga and Thermoanaerobacter, archaeal Vulcanisaeta and Hyperthermus) often dominated in high-temperature environments. Additionally, a positive correlation between Ammonia-Oxidizing Archaea (AOA) activity and temperature was detected. AOA activity increased from 17 to 52 pmol of NO2(-) per cell d(-1) with a temperature change from 50 to 70 °C.

  7. The impact of temperature on microbial diversity and AOA activity in the Tengchong Geothermal Field, China

    PubMed Central

    Li, Haizhou; Yang, Qunhui; Li, Jian; Gao, Hang; Li, Ping; Zhou, Huaiyang

    2015-01-01

    Using a culture-independent method that combines CARD-FISH, qPCR and 16S rDNA, we investigated the abundance, community structure and diversity of microbes along a steep thermal gradient (50–90 °C) in the Tengchong Geothermal Field. We found that Bacteria and Archaea abundance changed markedly with temperature changes and that the number of cells was lowest at high temperatures (90.8 °C). Under low-temperature conditions (52.3–74.6 °C), the microbial communities were dominated by Bacteria, which accounted for 60–80% of the total number of cells. At 74.6 °C, Archaea were dominant, and at 90.8 °C, they accounted for more than 90% of the total number of cells. Additionally, the microbial communities at high temperatures (74.6–90.8 °C) were substantially simpler than those at the low-temperature sites. Only a few genera (e.g., bacterial Caldisericum, Thermotoga and Thermoanaerobacter, archaeal Vulcanisaeta and Hyperthermus) often dominated in high-temperature environments. Additionally, a positive correlation between Ammonia-Oxidizing Archaea (AOA) activity and temperature was detected. AOA activity increased from 17 to 52 pmol of NO2− per cell d−1 with a temperature change from 50 to 70 °C. PMID:26608685

  8. Fracture development within a stratovolcano: The Karaha-Telaga Bodas geothermal field, Java volcanic arc

    USGS Publications Warehouse

    Nemcok, M.; Moore, J.N.; Allis, R.; McCulloch, J.

    2004-01-01

    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

  9. Fault rock mineralogy and fluid flow in the Coso Geothermal Field, CA

    NASA Astrophysics Data System (ADS)

    Davatzes, N. C.; Hickman, S. H.

    2005-12-01

    The minerals that comprise fault rock, their grain shapes, and packing geometry are important controls on fault zone properties such as permeability, frictional strength, and slip behavior. In this study we examine the role of mineralogy and deformation microstructures on fluid flow in a fault-hosted, fracture-dominated geothermal system contained in granitic rocks in the Coso Geothermal Field, CA. Initial examination of the mineralogy and microstructure of fault rock obtained from core and surface outcrops reveals three fault rock types. (1) Fault rock consisting of kaolinite and amorphous silica that contains large connected pores, dilatant brittle fractures, and dissolution textures. (2) Fault rock consisting of foliated layers of chlorite and illite-smectite separated by slip surfaces. (3) Fault rock consisting of poorly sorted angular grains, characterized by large variations in grain packing (pore size), and crack-seal textures. These different fault rocks are respectively associated with a high permeability upper boiling zone for the geothermal system, a conductively heated "caprock" at moderate to shallow depth associated with low permeability, and a deeper convectively heated region associated with enhanced permeability. Outcrop and hand-sample scale mapping, XRD analysis, and SEM secondary electron images of fault gouge and slip surfaces at different stages of development (estimated shear strain) are used to investigate the processes responsible for the development and physical properties of these distinct fault rocks. In each type of fault rock, mineral dissolution and re-precipitation in conjunction with the amount and geometry of porosity changes induced by dilation or compaction are the key controls on fault rock development. In addition, at the contacts between slip surfaces, abrasion and resulting comminution appear to influence grain size, sorting, and packing. Macroscopically, we expect the frictional strength of these characteristic fault rocks

  10. Gas and Isotope Geochemistry of 81 Steam Samples from Wells in The Geysers Geothermal Field, Sonoma and Lake Counties, California

    USGS Publications Warehouse

    Lowenstern, Jacob B.; Janik, Cathy J.; Fahlquist, Lynne; Johnson, Linda S.

    1999-01-01

    The Geysers geothermal field in northern California, with about 2000-MW electrical capacity, is the largest geothermal field in the world. Despite its importance as a resource and as an example of a vapor-dominated reservoir, very few complete geochemical analyses of the steam have been published (Allen and Day, 1927; Truesdell and others, 1987). This report presents data from 90 steam, gas, and condensate samples from wells in The Geysers geothermal field in northern California. Samples were collected between 1978 and 1991. Well attributes include sampling date, well name, location, total depth, and the wellhead temperature and pressure at which the sample was collected. Geochemical characteristics include the steam/gas ratio, composition of noncondensable gas (relative proportions of CO2, H2S, He, H2, O2, Ar, N2, CH4, and NH3), and isotopic values for deltaD and delta18O of H2O, delta13C of CO2, and delta34S of H2S. The compilation includes 81 analyses from 74 different production wells, 9 isotopic analyses of steam condensate pumped into injection wells, and 5 complete geochemical analyses on gases from surface fumaroles and bubbling pools. Most samples were collected as saturated steam and plot along the liquid-water/steam boiling curve. Steam-togas ratios are highest in the southeastern part of the geothermal field and lowest in the northwest, consistent with other studies. Wells in the Northwest Geysers are also enriched in N2/Ar, CO2 and CH4, deltaD, and delta18O. Well discharges from the Southeast Geysers are high in steam/gas and have isotopic compositions and N2/Ar ratios consistent with recharge by local meteoric waters. Samples from the Central Geysers show characteristics found in both the Southeast and Northwest Geysers. Gas and steam characteristics of well discharges from the Northwest Geysers are consistent with input of components from a high-temperature reservoir containing carbonrich gases derived from the host Franciscan rocks. Throughout the

  11. Fracture network, fluid pathways and paleostress at the Tolhuaca geothermal field

    NASA Astrophysics Data System (ADS)

    Pérez-Flores, Pamela; Veloso, Eugenio; Cembrano, José; Sánchez-Alfaro, Pablo; Lizama, Martín; Arancibia, Gloria

    2017-03-01

    In this study, we examine the fracture network of the Tolhuaca geothermal system located in the Southern Andean volcanic zone that may have acted as a pathway for migration and ascent of deep-seated fluids under the far/local stress field conditions of the area. We collected the orientation, slip-data and mineralogical content of faults and veins recovered on a ca. 1000 m deep borehole (Tol-1) located in the NW-flank of the Tolhuaca volcano. Tol-1 is a non-oriented, vertical borehole that recovered relatively young (<1 Ma) basaltic/andesitic volcanic rocks with subordinate pyroclastic/volcanoclastic interbedded units of Pleistocene age. Here, we examined and measured the inclination, geometry, texture, mineralogy, and relative sense of displacement of veins and faults. To determine the actual azimuthal orientation of fault and veins we reoriented 66 segments (89 standard mini-cores) of Tol-1 using stable Characteristic remanent magnetization component (ChRM) obtained by thermal demagnetization methodology. Paleo-declination of ChRM vectors was used to re-orient the borehole pieces, as well as fault and veins, to a common anchor orientation value consistent with the Geocentric Axial Dipole approximation (GAD). Inversion of RM-corrected fault-slip data reveals a local tensional stress field with a vertically oriented σ1 axis (083/74) and a subhorizontal, NS-trending σ3 axis (184/03). Within the topmost 400 m of the borehole, faults and veins are randomly oriented, whereas below 400 m depth, faults and veins show preferential NE-to EW-strikes and steep (>50°) dips. The EW-striking veins are compatible with the calculated local stress field whereas NE-striking veins are compatible with the regional stress field, the morphological elongation of volcanic centers, alignments of flank vents and dikes orientation. Our results demonstrate that the paleomagnetic methodology proved to be reliable and it is useful to re-orient vertical boreholes such as Tol-1. Furthermore

  12. Geothermal Life Cycle Calculator

    DOE Data Explorer

    Sullivan, John

    2014-03-11

    This calculator is a handy tool for interested parties to estimate two key life cycle metrics, fossil energy consumption (Etot) and greenhouse gas emission (ghgtot) ratios, for geothermal electric power production. It is based solely on data developed by Argonne National Laboratory for DOE’s Geothermal Technologies office. The calculator permits the user to explore the impact of a range of key geothermal power production parameters, including plant capacity, lifetime, capacity factor, geothermal technology, well numbers and depths, field exploration, and others on the two metrics just mentioned. Estimates of variations in the results are also available to the user.

  13. GEOTHERM user guide

    USGS Publications Warehouse

    Swanson, James R.

    1977-01-01

    GEOTHERM is a computerized geothermal resources file developed by the U.S. Geological Survey. The file contains data on geothermal fields, wells, and chemical analyses from the United states and international sources. The General Information Processing System (GIPSY) in the IBM 370/155 computer is used to store and retrieve data. The GIPSY retrieval program contains simple commands which can be used to search the file, select a narrowly defined subset, sort the records, and output the data in a variety of forms. Eight commands are listed and explained so that the GEOTHERM file can be accessed directly by geologists. No programming experience is necessary to retrieve data from the file.

  14. Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field, Baja, California, Mexico

    SciTech Connect

    Valette-Silver, J.N.; Esquer-Patino, I.; Elders, W.A.; Collier, P.C.; Hoagland, J.R.

    1981-01-01

    Surface emissions from the Cerro Prieto geothermal reservoir are restricted to a 100 km/sup 2/ area on the western side of the field, near the volcano Cerro Prieto and the lake Laguna Vulcano. Some 57 surface emissions, explored in 1979, were classified into hot springs, mud pots, pools, fumaroles and geysers (Valette and Esquer-Patino, 1979). 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/sup 0/C: increase of quartz, feldspar and illite, with subsequent disappearance of kaolinite, montmorillonite, calcite and dolomite. These mineral assemblages seem to be characteristics of the discharge from high intensity geothermal fields.

  15. Locating an active fault zone in Coso geothermal field by analyzing seismic guided waves from microearthquake data

    SciTech Connect

    SGP-TR-150-16

    1995-01-26

    Active fault systems usually provide high-permeability channels for hydrothermal outflow in geothermal fields. Locating such fault systems is of a vital importance to plan geothermal production and injection drilling, since an active fault zone often acts as a fracture-extensive low-velocity wave guide to seismic waves. We have located an active fault zone in the Coso geothermal field, California, by identifying and analyzing a fault-zone trapped Rayleigh-type guided wave from microearthquake data. The wavelet transform is employed to characterize guided-wave's velocity-frequency dispersion, and numerical methods are used to simulate the guided-wave propagation. The modeling calculation suggests that the fault zone is {approx} 200m wide, and has a P wave velocity of 4.80 km/s and a S wave velocity of 3.00 km/s, which is sandwiched between two half spaces with relatively higher velocities (P wave velocity 5.60 km/s, and S wave velocity 3.20 km/s). zones having vertical or nearly vertical dipping fault planes.

  16. Aluto-Langano geothermal field, Ethiopian Rift Valley: Physical characteristics and the effects of gas on well performance

    SciTech Connect

    Gizaw, B. )

    1993-04-01

    This study, which focuses on the Aluto-Langano geothermal field, is part of the ongoing investigation of the geothermal systems in the Ethiopian Rift Valley. Aluto-Langano is a water-dominated gas-rich geothermal field, with a maximum temperature close to 360[degree]C, in the Lakes District region of the Ethiopian Rift Valley. The upflow zone for the system lies along a deep, young NNE trending fault and is characterized by boiling. As a result, the deep upflow zone loses some water as steam and produces a cooler saline shallow aquifer. The high partial pressure of carbon dioxide (about 30 bar in the reservoir) depresses the water table and restricts boiling to deeper levels. The main aquifer for the systems is in the Tertiary ignimbrite, which lies below 1400 m. The capacity of the existing wells is close to 7 MW[sub c]: the energy potential of the area is estimated to be between 3000 and 6000 MW[sub t] yr/km[sup 3], or 10-20 MW[sub c]/km[sup 3] for over 30 years.

  17. Monitoring Heat Losses Using Landsat ETM + Thermal Infrared Data: a Case Study in Unzen Geothermal Field, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Mia, Md. Bodruddoza; Bromley, Chris J.; Fujimitsu, Yasuhiro

    2013-12-01

    The Unzen geothermal field, our study area, is situated in the Shimabara Peninsula of Kyushu Island in Japan and is an area of active fumaroles.. Our prime objectives were (1) to estimate radiative heat flux (RHF), (2) to calculate approximately the heat discharge rate (HDR) using the relationship of RHF with the total heat loss derived from two geothermal field studies, and (3) finally, to monitor RHF as well as HDR in our study area using seven sets of Landsat 7 ETM + images from 2000 to 2009. We used the normalized differential vegetation index (NDVI) method for spectral emissivity estimation, the mono-window algorithm for land surface temperature (LST), and the Stefan-Boltzmann equation analyzing those satellite TIR images for RHF. We estimated that the maximum RHF was about 251 W/m2 in 2005 and minimum was about 27 W/m2 in 2001. The highest total RHF was about 39.1 MW in 2005 and lowest was about 12 MW in 2001 in our study region. We discovered that the estimated RHF was about 15.7 % of HDR from our studies. We applied this percentage to estimate HDR in Unzen geothermal area. The monitoring results showed a single fold trend of HDR from 2000 to 2009 with highest about 252 MW in 2005 and lowest about 78 MW in 2001. In conclusion, TIR remote sensing is thought as the best option for monitoring heat losses from fumaroles with high efficiency and low cost.

  18. Microbial diversity of acidic hot spring (kawah hujan B) in geothermal field of kamojang area, west java-indonesia.

    PubMed

    Aditiawati, Pingkan; Yohandini, Heni; Madayanti, Fida; Akhmaloka

    2009-01-01

    Microbial communities in an acidic hot spring, namely Kawah Hujan B, at Kamojang geothermal field, West Java-Indonesia was examined using culture dependent and culture independent strategies. Chemical analysis of the hot spring water showed a characteristic of acidic-sulfate geothermal activity that contained high sulfate concentrations and low pH values (pH 1.8 to 1.9). Microbial community present in the spring was characterized by 16S rRNA gene combined with denaturing gradient gel electrophoresis (DGGE) analysis. The majority of the sequences recovered from culture-independent method were closely related to Crenarchaeota and Proteobacteria phyla. However, detail comparison among the member of Crenarchaeota showing some sequences variation compared to that the published data especially on the hypervariable and variable regions. In addition, the sequences did not belong to certain genus. Meanwhile, the 16S Rdna sequences from culture-dependent samples revealed mostly close to Firmicute and gamma Proteobacteria.

  19. Microbial Diversity of Acidic Hot Spring (Kawah Hujan B) in Geothermal Field of Kamojang Area, West Java-Indonesia

    PubMed Central

    Aditiawati, Pingkan; Yohandini, Heni; Madayanti, Fida; Akhmaloka

    2009-01-01

    Microbial communities in an acidic hot spring, namely Kawah Hujan B, at Kamojang geothermal field, West Java-Indonesia was examined using culture dependent and culture independent strategies. Chemical analysis of the hot spring water showed a characteristic of acidic-sulfate geothermal activity that contained high sulfate concentrations and low pH values (pH 1.8 to 1.9). Microbial community present in the spring was characterized by 16S rRNA gene combined with denaturing gradient gel electrophoresis (DGGE) analysis. The majority of the sequences recovered from culture-independent method were closely related to Crenarchaeota and Proteobacteria phyla. However, detail comparison among the member of Crenarchaeota showing some sequences variation compared to that the published data especially on the hypervariable and variable regions. In addition, the sequences did not belong to certain genus. Meanwhile, the 16S Rdna sequences from culture-dependent samples revealed mostly close to Firmicute and gamma Proteobacteria. PMID:19440252

  20. Report on dipole-dipole resistivity and technology transfer at the Ahuachapan Geothermal field Ahuachapan, El Salvador

    SciTech Connect

    Fink, J.B. )

    1988-08-01

    The Ahuachapan Geothermal Field (AGF) is a 90 megawatt geothermal-sourced powerplant operated by the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) of El Salvador. During the period November 1987 through May 1988 a deep resistivity survey and technology transfer was performed at the AGF at the request of Los Alamos National Laboratory (LANL) as part of a United States Agency for International Development (USAID) project. The resistivity surveying is ongoing at the time of this report under the supervision of CEL personnel. LANL and contract personnel were present at the site during performance of the initial surveying for the purpose of technology transfer. This report presents the results and interpretation of the two initial resistivity survey lines performed on site during and shortly after the technology transfer period.

  1. Geothermal Energy - An Emerging Resource

    SciTech Connect

    Berg, John R.

    1987-01-20

    Address on the Department of Energy's overall energy policy, the role of alternative energy sources within the policy framework, and expectations for geothermal energy. Commendation of the industry's decision to pursue the longer-term field effort while demand for geothermal energy is low, and thus prepare for a substantial geothermal contribution to the nation's energy security.

  2. Determination of Microbial Diversity and Nitrogen Cycling from Kizildere Geothermal Field with Next Generation Sequencing

    NASA Astrophysics Data System (ADS)

    Gulecal, Y.; Dilek, Y.

    2012-12-01

    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

  3. Simulation studies for wells AH-4bis/AH-17 and AH-18, Ahuachapan Geothermal Field

    SciTech Connect

    Monterrosa, Manuel Ernesto

    1996-01-24

    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.

  4. Simulations studies for wells AH-4bis/AH-17 and AH-18, Ahuachapan Geothermal Field

    SciTech Connect

    Monterrosa, M.E.

    1996-12-31

    Well AH-4{sub bis} 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 diameters 13 5/8 and 9 5/8 inches in order to estimate its production and to know its economic feasibility. The simulation results indicate 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-4b{sub bis}. 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 necessary to estimate the possible production conditions at that zone. The results indicate a high probability 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.

  5. Results of injection and tracer tests in Olkaria East Geothermal Field

    SciTech Connect

    Ambusso, Willis J.

    1994-01-20

    This paper presents results of a six month Injection and Tracer test done in Olkaria East Geothermal Field The Injection tests show that commencement of injection prior to onset of large drawdown in the reservoir leads to greater sustenance of well production and can reduce well cycling which is a common feature of wells in Olkaria East Field. For cases where injection is started after some drawdown has occurred in the reservoir, injection while leading to improvement of well output can also lead to increase in well cycling which is a non desirable side effect. Tracer tests reveal slow rate of fluid migration (< 5 m/hr). However estimates of the cumulative tracer returns over the period of injection is at least 31% which is large and reveals the danger of late time thermal drawdown and possible loss of production. It is shown in the discussion that the two sets of results are consistent with a reservoir where high permeability occurs along contact surfaces which act as horizontal "fractures" while the formations between the "fractures" have low permeability. This type of fracture system will lead to channeled flow of injected fluid and therefore greater thermal depletion along the fractures while formations further from the fracture would still be at higher temperature. In an attempt to try and achieve a more uniform thermal depletion in the reservoir, it is proposed that continuous injection be done for short periods (~2 years) and this be followed by recovery periods of the nearly the same length of time before resumption of injection again.

  6. An integrated deep electrical resistivity model of the Larderello geothermal field (Italy)

    NASA Astrophysics Data System (ADS)

    Rizzo, Enzo; Capozzoli, Luigi; De martino, Gregory; Godio, Alberto; Manzella, Adele; Perciante, Felice; Santilano, Alessandro

    2017-04-01

    A new deep electrical resistivity acquisition was carried out in Larderello geothermal area (Tuscania Region, Italy) by 3D Deep Electrical Resistivity Tomography (3D-DERT) and Magnetotelluric (M) acquisition. The investigated area is located close the Venelle2 well in the southern part of Larderello site, where there is the oldest field in the world under exploitation for power production (actual installed capacity is about 795 MWe). A vapour-dominated system is exploited to depth over 3500 m, with temperatures exceeding 350°C, from two different reservoirs. The Larderello area has been investigated by many geological and geophysical data of previous exploration projects but nowadays several critical issues on deep features of the field are still matter of debate, e.g., permeability distribution in the hydrothermal reservoir and the presence of fluids at supercritical condition at depth. The 3D-DERT system was designed by Surface-Surface and Surface-Hole electrode distributions in the area around Venelle2 well covering an area around 16km2. The well (kindly provided by Enel GP) was accessible down to 1.6 km with a temperature up to 250°C and a metallic casing down to 1 km. The in-hole thermal cable is characterized by n.12 flexible metallic electrodes with an electrodes space of 50m covering the open-hole portion (1050m-1600m). The surface electrodes are located around the Venelle2 hole on n.23 different positions connected to automatic dataloger to acquire the drop of potential and to transmitter device to inject the current (5-10A). The crucial task was the data processing, considering the large distance between the Tx and Rx systems that strongly reduces the signal to-noise ratio. To overcome this drawback, for each quadripole position the corresponding voltage signal was filtered, stored and processed with advanced statistical packages. The new 22 station were installed in the studied area and the data were carried out taking in account a permanent remote

  7. Origin and evolution of Pliocene Pleistocene granites from the Larderello geothermal field (Tuscan Magmatic Province, Italy)

    NASA Astrophysics Data System (ADS)

    Dini, A.; Gianelli, G.; Puxeddu, M.; Ruggieri, G.

    2005-04-01

    Extensive, mainly acidic peraluminous magmatism affected the Tuscan Archipelago and the Tuscan mainland since late Miocene, building up the Tuscan Magmatic Province (TMP) as the Northern Apennine fold belt was progressively thinned, heated and intruded by mafic magmas. Between 3.8 and 1.3 Ma an intrusive complex was built on Larderello area (Tuscan mainland) by emplacement of multiple intrusions of isotopically and geochemically distinct granite magmas. Geochemical and isotopic investigations were carried out on granites cored during drilling exploration activity on the Larderello geothermal field. With respect to the other TMP granites the Larderello intrusives can be classified as two-mica granites due to the ubiquitous presence of small to moderate amounts of F-rich magmatic muscovite. They closely resemble the almost pure crustal TMP acidic rocks and do not show any of the typical petrographic features commonly observed in the TMP hybrid granites (enclaves, patchy zoning of plagioclase, amphibole clots). On the basis of major and trace elements, as well as REE patterns, two groups of granites were proposed: LAR-1 granites (3.8-2.3 Ma) originated by biotite-muscovite breakdown, and LAR-2 granites (2.3-1.3 Ma) generated by muscovite breakdown. At least three main crustal sources (at 14-23 km depth), characterized by distinct ɛNd( t) and 87Sr/ 86Sr values, were involved at different times, and the magmas produced were randomly emplaced at shallow levels (3-6 km depth) throughout the entire field. The partial melting of a biotite-muscovite-rich source with low ɛNd( t) value (about -10.5) produced the oldest intrusions (about 3.8-2.5 Ma). Afterwards (2.5-2.3 Ma), new magmas were generated by another biotite-rich source having a distinctly higher ɛNd( t) value (-7.9). Finally, a muscovite-rich source with high ɛNd( t) (about -8.9) gave origin to the younger group of granites (2.3-1.0 Ma). The significant Sr isotope disequilibrium recorded by granites belonging to

  8. Micro-seismicity, fault structure, and hydrologic compartmentalization within the Coso Geothermal Field, California, from 1996 until present

    NASA Astrophysics Data System (ADS)

    Kaven, J. O.; Hickman, S.; Davatzes, N. C.

    2010-12-01

    Geothermal reservoirs derive their capacity for fluid and heat transport in large part from faults and fractures. In conventional reservoirs, preexisting faults and fractures are the main conduits for fluid flow, while in enhanced geothermal systems (EGS), fractures and faults that are generated or enlarged (i.e., through increases in surface area and aperture) by hydraulic stimulation provide the main pathways for fluids and heat. In both types of geothermal systems, seismicity can be used to locate active faults, which can act either as conduits for along-fault fluid flow and/or barriers to cross-fault flow. We relocate 14 years of seismicity in the Coso Geothermal Field (CGF) using differential travel time relocations to improve our knowledge of the subsurface geologic and hydrologic structure. The seismicity at Coso has been recorded on a local network operated by the Navy Geothermal Program, which provides exceptional coverage and quality of data. Using the relocated catalog, we employ a newly developed algorithm for fault identification using the spatial seismicity distribution and a priori constraints on fault zone width derived from local geologic mapping. We avoid having to assume a particular fault-normal seismicity distribution by finding regions of maximum spatial seismicity density. Assuming a maximum spatial density is physically plausible since faults, or more accurately fault zones, generate most of the associated seismicity within a central fault core or damage zone. These techniques are developed for naturally occurring, active faults within the CGF on which seismicity is induced, in part, by changes in production and injection. They can also be applied to EGS if seismicity is induced within newly created fracture systems of comparable width or if this seismicity is generated by stimulating pre-existing, partially sealed faults. The results of the relocations reveal that clouds of seismicity shrink into distinct oblate volumes of seismicity in

  9. Characterization of injection wells in a fractured reservoir using PTS logs, Steamboat Hills Geothermal Field, Nevada, USA

    SciTech Connect

    Goranson, Colin; Combs, Jim

    1995-01-26

    The Steamboat Hills Geothermal Field in northwestern Nevada, about 15 km south of Reno, is a shallow (150m to 825m) moderate temperature (155 C to 168 C) liquid-dominated geothermal reservoir situated in highly-fractured granodiorite. Three injection wells were drilled and completed in granodiorite to dispose of spent geothermal fluids from the Steamboat II and III power plants (a 30 MW air-cooled binary-type facility). Injection wells were targeted to depths below 300m to inject spent fluids below producing fractures. First, quasi-static downhole pressure-temperature-spinner (PTS) logs were obtained. Then, the three wells were injection-tested using fluids between 80 C and 106 C at rates from 70 kg/s to 200 kg/s. PTS logs were run both up and down the wells during these injection tests. These PTS surveys have delineated the subsurface fracture zones which will accept fluid. The relative injectivity of the wells was also established. Shut-in interzonal flow within the wells was identified and characterized.

  10. Assessment of the Appalachian Basin Geothermal Field: Combining Risk Factors to Inform Development of Low Temperature Projects

    NASA Astrophysics Data System (ADS)

    Smith, J. D.; Whealton, C.; Camp, E. R.; Horowitz, F.; Frone, Z. S.; Jordan, T. E.; Stedinger, J. R.

    2015-12-01

    Exploration methods for deep geothermal energy projects must primarily consider whether or not a location has favorable thermal resources. Even where the thermal field is favorable, other factors may impede project development and success. A combined analysis of these factors and their uncertainty is a strategy for moving geothermal energy proposals forward from the exploration phase at the scale of a basin to the scale of a project, and further to design of geothermal systems. For a Department of Energy Geothermal Play Fairway Analysis we assessed quality metrics, which we call risk factors, in the Appalachian Basin of New York, Pennsylvania, and West Virginia. These included 1) thermal field variability, 2) productivity of natural reservoirs from which to extract heat, 3) potential for induced seismicity, and 4) presence of thermal utilization centers. The thermal field was determined using a 1D heat flow model for 13,400 bottomhole temperatures (BHT) from oil and gas wells. Steps included the development of i) a set of corrections to BHT data and ii) depth models of conductivity stratigraphy at each borehole based on generalized stratigraphy that was verified for a select set of wells. Wells are control points in a spatial statistical analysis that resulted in maps of the predicted mean thermal field properties and of the standard error of the predicted mean. Seismic risk was analyzed by comparing earthquakes and stress orientations in the basin to gravity and magnetic potential field edges at depth. Major edges in the potential fields served as interpolation boundaries for the thermal maps (Figure 1). Natural reservoirs were identified from published studies, and productivity was determined based on the expected permeability and dimensions of each reservoir. Visualizing the natural reservoirs and population centers on a map of the thermal field communicates options for viable pilot sites and project designs (Figure 1). Furthermore, combining the four risk

  11. Field stress corrosion tests in brine environments of the Salton Sea known geothermal resource area

    SciTech Connect

    Carter, J.P.; Cramer, S.D.

    1980-01-01

    Corrosion research is being conducted to determine suitable construction materials for geothermal resource recovery plants. As part of this research, a 30-day stress corrosion test was conducted at the Salton Sea Known Geothermal Resource Area on seven iron- and nickel-base alloys in four brine and steam process streams using wellhead brine from geothermal well Magmamax 1. The tests showed transgranular cracking of AISI 316L stainless steel and intergranular and transgranular cracking of AISI 430 stainless steel in all four process streams. E-Brite 26-1 exhibited intergranular and transgranular cracking in three of the four process streams. Carbon steel, Inconel 625 and Hastelloys G and C-276 show no evidence of stress corrosion cracking.

  12. Thermal investigation in S. Pedro do Sul low enthalpy geothermal field (Portugal)

    SciTech Connect

    Correia, A.; Ramalho, E.C.; Lourenco, M.C.; Cruz, J.F. ||

    1997-12-31

    The S. Pedro Sul thermal springs are one of the most important low enthalpy geothermal areas in mainland Portugal. The water temperature at emergence points can reach values as high as 67{degrees}C with water flows of 10 l/s. Based on silica geothermometry, the regional heat flow density is estimated as 170 m W/m{sup 2}, and the heat production of the S. Pedro do Sul granite, that crops out in the region where the thermal springs are located, is about 11 {mu}W/m{sup 3}. These values allow an estimate that the depth of the geothermal reservoir is about 2,000 metres. The geothermal reservoir is fed by meteoric water that is heated to temperatures of about 130{degrees}C at 2,000 metres depth. Then, the heated water flows to the surface through the Termas fault, mixing with colder water at shallow depths.

  13. Hot-dry-rock geothermal-reservoir fracturing initial field operations - 1982

    SciTech Connect

    Rowley, J.C.; Pettitt, R.A.; Matsunaga, I.; Dreesen, D.S.; Nicholson, R.W.; Sinclair, A.R.

    1983-01-01

    Initial fracturing operations were conducted during 1982 to create a hot dry rock (HDR) geothermal reservoir at the Los Alamos Fenton Hill site. A preliminary work-over/cleaning operation in November to December 1981 had cleared the injection well, EE-2, and a detailed, comprehensive plan was prepared to accomplish the objectives of hydraulically connecting the injection and production wells. In January 1982, open-hole reservoir sections of both the production and injection wells were pressurized below the 9-5/8 in. casing. The injection well, EE-2, did not take fluid at 2200 psi, but the production well, EE-3, had a lost circulation zone and took water over a 240 ft zone immediately below the production casing. Subsequent field operations from May through December 14, 1982 involved ten major hydraulic injection and/or equipment tests. These ranged from 14,180 ft (4322 m) deep open-hole packer tests to installation of a cemented-in liner/PBR system. Injections of up to 1.3 x 10 gals. were performed in the injection well. Both wells were fractured in zones just below the production casings. Although several large volume injections were accomplished, hydraulic communication between wells was not achieved. Severe hardware problems were encountered due to temperature limitations, the high fracture gradient (breakdown and injection pressures), and the presence of CO/sub 2/ and H/sub 2/S during fracture back-flow and well venting. On-line and post-test analyses of seismic monitoring confirmed that fractures were created in each well that converged on, but did not intersect, the neighboring well.

  14. Gases and water isotopes in a geochemical section across the Larderello, Italy, geothermal field

    USGS Publications Warehouse

    Truesdell, A.H.; Nehring, N.L.

    1978-01-01

    Steam samples from six wells (Colombaia, Pineta, Larderello 57, Larderello 155, Gabbro 6, and Gabbro 1) in a south to north section across the Larderello geothermal field have been analyzed for inorganic and hydrocarbon gases and for oxygen-18 and deuterium of steam. The wells generally decrease in depth and increase in age toward the south. The steam samples are generally characterized by (1) Total gas contents increasing south to north from 0.003 to 0.05 mole fraction; (2) Constant CO2 (95??2 percent); near constant H2S (1.6??0.8), N2 (1.2??0.8), H2 (2??1), CH4 (1.2??1), and no O2 in the dry gas; (3) Presence of numerous, straight chain and branched C2 to C6 hydrocarbons plus benzene in amounts independent of CH4 contents with highest concentrations in the deeper wells; (4) Oxygen-18 contents of steam increasing south to north from -5.0??? to -0.4??? with little change in deuterium (-42??2???). These observations are interpreted as showing: (1) Decreasing gas contents with amount of production because the proportion of steam boiled from liquid water increases with production; (2) Synthesis of CH4 from H2 and CO2 with CO2 and H2 produced by thermal metamorphism and rock-water reactions; (3) Extraction of C2 to C6 hydrocarbons from rock organic matter; (4) Either oxygen isotope exchange followed by distillation of steam from the north toward the south (2 plates at ???220??C) or mixture of deeper more-exchange waters from the north with shallow, less-exchanged recharging waters from the south. ?? 1978 Birkha??user Verlag.

  15. A RESERVOIR ENGINEERING ANALYSIS OF A VAPOR-DOMINATED GEOTHERMAL FIELD

    SciTech Connect

    Dee, J.F.; Brigham, W.E.

    1985-01-22

    The purpose of the study is to develop a simplified model to match past performances of a vapor-dominated geothermal reservoir and to predict future production rates and ultimate reserves. The data are fictitious, but are based on real data. A lumped parameter model was developed for the reservoir that is similar to the model developed by Brigham and Neri (1979, 1980) for the Gabbro zone, and a deliverability model was developed to predict the life and future producing rate declines of the reservoir. This report presents the development and results of this geothermal reservoir analysis.

  16. Composition and origin of rhyolite melt intersected by drilling in the Krafla geothermal field, Iceland

    USGS Publications Warehouse

    Zierenberg, R.A.; Schiffman, P.; Barfod, G.H.; Lesher, C.E.; Marks, N.E.; Lowenstern, Jacob B.; Mortensen, A.K.; Pope, E.C.; Bird, D.K.; Reed, M.H.; Friðleifsson, G.O.; Elders, W.A.

    2013-01-01

    The Iceland Deep Drilling Project Well 1 was designed as a 4- to 5-km-deep exploration well with the goal of intercepting supercritical hydrothermal fluids in the Krafla geothermal field, Iceland. The well unexpectedly drilled into a high-silica (76.5 % SiO2) rhyolite melt at approximately 2.1 km. Some of the melt vesiculated while extruding into the drill hole, but most of the recovered cuttings are quenched sparsely phyric, vesicle-poor glass. The phenocryst assemblage is comprised of titanomagnetite, plagioclase, augite, and pigeonite. Compositional zoning in plagioclase and exsolution lamellae in augite and pigeonite record changing crystallization conditions as the melt migrated to its present depth of emplacement. The in situ temperature of the melt is estimated to be between 850 and 920 °C based on two-pyroxene geothermometry and modeling of the crystallization sequence. Volatile content of the glass indicated partial degassing at an in situ pressure that is above hydrostatic (~16 MPa) and below lithostatic (~55 MPa). The major element and minor element composition of the melt are consistent with an origin by partial melting of hydrothermally altered basaltic crust at depth, similar to rhyolite erupted within the Krafla Caldera. Chondrite-normalized REE concentrations show strong light REE enrichment and relative flat patterns with negative Eu anomaly. Strontium isotope values (0.70328) are consistent with mantle-derived melt, but oxygen and hydrogen isotope values are depleted (3.1 and −118 ‰, respectively) relative to mantle values. The hydrogen isotope values overlap those of hydrothermal epidote from rocks altered by the meteoric-water-recharged Krafla geothermal system. The rhyolite melt was emplaced into and has reacted with a felsic intrusive suite that has nearly identical composition. The felsite is composed of quartz, alkali feldspar, plagioclase, titanomagnetite, and augite. Emplacement of the rhyolite magma has resulted in partial melting of

  17. Causality between expansion of seismic cloud and maximum magnitude of induced seismicity in geothermal field

    NASA Astrophysics Data System (ADS)

    Mukuhira, Yusuke; Asanuma, Hiroshi; Ito, Takatoshi; Häring, Markus

    2016-04-01

    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

  18. Composition and origin of rhyolite melt intersected by drilling in the Krafla geothermal field, Iceland

    NASA Astrophysics Data System (ADS)

    Zierenberg, R. A.; Schiffman, P.; Barfod, G. H.; Lesher, C. E.; Marks, N. E.; Lowenstern, J. B.; Mortensen, A. K.; Pope, E. C.; Bird, D. K.; Reed, M. H.; Friðleifsson, G. Ó.; Elders, W. A.

    2013-02-01

    The Iceland Deep Drilling Project Well 1 was designed as a 4- to 5-km-deep exploration well with the goal of intercepting supercritical hydrothermal fluids in the Krafla geothermal field, Iceland. The well unexpectedly drilled into a high-silica (76.5 % SiO2) rhyolite melt at approximately 2.1 km. Some of the melt vesiculated while extruding into the drill hole, but most of the recovered cuttings are quenched sparsely phyric, vesicle-poor glass. The phenocryst assemblage is comprised of titanomagnetite, plagioclase, augite, and pigeonite. Compositional zoning in plagioclase and exsolution lamellae in augite and pigeonite record changing crystallization conditions as the melt migrated to its present depth of emplacement. The in situ temperature of the melt is estimated to be between 850 and 920 °C based on two-pyroxene geothermometry and modeling of the crystallization sequence. Volatile content of the glass indicated partial degassing at an in situ pressure that is above hydrostatic (~16 MPa) and below lithostatic (~55 MPa). The major element and minor element composition of the melt are consistent with an origin by partial melting of hydrothermally altered basaltic crust at depth, similar to rhyolite erupted within the Krafla Caldera. Chondrite-normalized REE concentrations show strong light REE enrichment and relative flat patterns with negative Eu anomaly. Strontium isotope values (0.70328) are consistent with mantle-derived melt, but oxygen and hydrogen isotope values are depleted (3.1 and -118 ‰, respectively) relative to mantle values. The hydrogen isotope values overlap those of hydrothermal epidote from rocks altered by the meteoric-water-recharged Krafla geothermal system. The rhyolite melt was emplaced into and has reacted with a felsic intrusive suite that has nearly identical composition. The felsite is composed of quartz, alkali feldspar, plagioclase, titanomagnetite, and augite. Emplacement of the rhyolite magma has resulted in partial melting of

  19. The geothermal field below the city of Berlin, Germany: Results from structurally and parametrically improved 3D Models

    NASA Astrophysics Data System (ADS)

    Frick, Maximilian; Sippel, Judith; Cacace, Mauro; Scheck-Wenderoth, Magdalena

    2016-04-01

    The goal of this study was to quantify the influence of the geological structure and geophysical parametrization of model units on the geothermal field as calculated by 3D numerical simulations of coupled fluid and heat transport for the subsurface of Berlin, Germany. The study area is located in the Northeast German Basin which is filled with several kilometers of sediments. This sedimentary infill includes the clastic sedimentary units Middle Buntsandstein and Sedimentary Rotliegend which are of particular interest for geothermal exploration. Previous studies conducted in the Northeast German Basin have already shown the geometries and properties of the geological units majorly control the distribution of subsurface temperatures. In this study we followed a two-step approach, where we first improved an existing structural model by integrating newly available 57 geological cross-sections, well data and deep seismics (down to ~4 km). Secondly, we performed a sensitivity analysis investigating the effects of varying physical fluid and rock properties on the subsurface temperature field. The results of this study show, that the structural configuration of model units exerts the highest influence on the geothermal field (up to ± 23 K at 1000 m below sea level). Here, the Rupelian clay aquitard, displaying a heterogeneous thickness distribution, locally characterized by hydrogeological windows (i.e. domains of no thickness) enabling intra-aquifer groundwater circulation has been identified as major controlling factor. The new structural configuration of this unit (more continuous, less numerous hydrogeological windows) also leads to a reduction of the influence of different boundary conditions and heat transport mechanisms considered. Additionally, the models results show that calculated temperatures highly depend on geophysical properties of model units whereas the hydraulic conductivity of the Cenozoic succession was identified as most dominant, leading to changes

  20. The role of active and ancient geothermal systems in evolution of Grant Canyon oil field, Railroad Valley, Nye County, Nevada

    SciTech Connect

    Hulen, J.B. ); Bereskin, S.R. ); Bortz, L.C.

    1991-06-01

    Since discovery in 1983, the Grant Canyon field has been among the most prolific oil producers (on a per-well basis) in the US. Production through June 1990 was 12,935,630 bbl of oil, principally from two wells which in tandem have consistently yielded more than 6,000 bbl of oil per day. The field is hosted by highly porous Devonian dolomite breccia loosely cemented with hydrothermal quartz. Results of fluid-inclusion and petrographic research in progress at Grant Canyon suggest that paleogeothermal and perhaps currently circulating geothermal systems may have played a major role in oil-reservoir evolution. For example, as previously reported, the breccia-cementing quartz hosts primary aqueous, aqueous/oil, and oil fluid inclusions which were trapped at about 120C (average homogenization temperature) and document initial oil migration and entrapment as droplets or globules dispersed in dilute (< 2.2 wt.% equivalent NaCl) aqueous solutions. Additional evidence of geothermal connection is that the horst-block trap at Grant Canyon is top and side sealed by valley-fill clastic and volcanic rocks which are locally hydrothermally altered and calcite flooded. These secondary seals are enhanced by disseminated, solid asphaltic residues locally accounting for 23% (volume) of the rock. Current reservoir temperatures at Grant Canyon (120C) and the adjacent Bacon Flat field (171C) attest to vigorous contemporary geothermal activity. Based on results of the authors' Grant Canyon work to date, they suggest that active and paleohydrothermal systems could be viable petroleum exploration targets in otherwise favorable terrain elsewhere in the Basin and Range.

  1. Gas Geothermometry for Drilhole Fluids from Vapor Dominated and Hot Water Geothermal Fields

    SciTech Connect

    D'Amore, Franco; Truesdall, Alfred H.

    1980-12-16

    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

  2. Geochronology of the Larderello geothermal field: new data and the ``closure temperature'' issue

    NASA Astrophysics Data System (ADS)

    Villa, Igor M.; Puxeddu, Mariano

    1994-02-01

    The Larderello geothermal field is generally accepted to have been produced by a granite intrusion at 4 9 km depth. Hydrothermal parageneses and fluid inclusions always formed at temperatures greater than or equal to the current ones, which implies that the field has always undergone a roughly monotonic cooling history (fluctuations < 40 K) since intrusion of the granite at 4 Ma. The heat required to maintain the thermal anomaly over such a long period is supplied by a seismically anomalous body of ≈ 32000 km3 rooted in the mantle. Borehole minerals from Larderello are thus a unique well-calibrated natural example of thermally induced Ar and Sr loss under geological conditions and time spans. The observations (biotites retain Ar above 450°C) agree well with other, albeit less precise, geological determinations, but contrast with laboratory determinations of diffusivity from the literature. We therefore performed a hydrothermal experiment on two Larderello biotites and derived a diffusivity D Lab(370°C)=5.3·10-18 cm2s-1, in agreement with published estimates of diffusivity in annite. From D Lab and the rejuvenation of the K/Ar ages we calculate maximum survival times at the present in-hole temperatures. They trend smoothly over almost two orders of magnitude from 352 ka to 5.3 ka, anticorrelating with depth: laboratory diffusivities are inconsistent not only with geological facts, but also among themselves. From the geologically constrained lifetime of the thermal anomaly we derive a diffusivity D G(370°C)=3.81·1021 cm2s-1, 3±1 orders of magnitude lower than D Lab. The cause of these discrepancies must be sought among various laboratory artefacts: overstepping of a critical temperature T *; enhanced diffusivities in “wet” experiments; presence of fast pathway (dislocation and pipe) diffusion, and of dissolution/reprecipitation reactions, which we imaged by scanning electron microscopy. These phenomena are minor in geological settings: in the absence of

  3. Conceptual Model Evaluation of the Astor Pass Geothermal Field, Western Nevada

    NASA Astrophysics Data System (ADS)

    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.

    2012-12-01

    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

  4. Chemical composition of deep hydrothermal fluids in the Ribeira Grande geothermal field (São Miguel, Azores)

    NASA Astrophysics Data System (ADS)

    Carvalho, M. R.; Forjaz, V. H.; Almeida, C.

    2006-08-01

    The Ribeira Grande geothermal field is a water-dominated geothermal system, located within Água de Pau/Fogo Volcano in the central part of the São Miguel Island. This geothermal system is exploited for energy production by wells sustaining two power plants. The wells produce from a formation of pillow lavas divided into different aquifers, with a fairly isothermal zone from 800 to 1300 m in depth, where reservoir temperature reaches 230 to 245 °C. Below the depth of 1300 m there is a slight temperature reversal. The fluid produced has excess enthalpy and, separated at atmospheric pressure, is characterized by mineralization of sodium-chloride type up to 6-7 g/l, the concentration of dissolved silica varies between 450 and 650 mg/l and the pH ranges between 8 and 8.6. The gas phase is dominantly CO 2, at a concentration of 98% of NCG. The composition of the deep geothermal fluid was obtained by computer simulation, using the WATCH program, and was compared with the composition of the bottom-hole samples. The approximations, in this simulation, were considered the single- and multi-step steam separation. The reference temperatures were based on: (i) the measured temperature in wells; (ii) the Na/K geothermometric temperature and (iii) the enthalpy-saturation temperature. According to both the measured and geothermometric temperatures, the deep fluid of the wells has two phases with a steam fraction up to 0.34, at higher well discharges. The measured enthalpy is always greater than the calculated enthalpy. The calcite equilibrium indicates scaling, since the fluid is flashing, around 2.28 mg/l CaCO 3 at the maximum discharge. The geothermal wells exploit three different aquifers, the lower of which is liquid and slightly colder than the upper ones. The intermediate is a two-phase aquifer with a steam fraction up to 0.081. The upper aquifer is probably of steam phase. The main differences between the aquifers are the temperature and boiling; both enthalpy and

  5. Some aspects of the response of geothermal reservoirs to brine reinjection with application to the Cerro Prieto Field

    SciTech Connect

    Tsang, C.F.; Bodvarsson, G.S.; Lippmann, M.J.; Rivera, J.R.

    1980-01-01

    In this paper, preliminary results of two reinjection studies will be described: (1) Initial investigation of several possible reinjection patterns for the Cerro Prieto geothermal field have been made based on a method developed by Gringarten and Sauty (1975). The resulting data show what may be expected from different reinjection schemes and may provide useful guidelines for the eventual choice of an optimal well arrangement. A numerical model was used to study the injection pressure expected when colder water is injected into a hot reservoir. 3 refs.

  6. Palinpinon I geothermal field production well PN-32d: Review of acid stimulation treatment. Export trade information

    SciTech Connect

    1994-05-19

    The study, conducted by the Mesquite Group, Inc., was funded by the U.S. Trade and Development Agency on behalf of the Philippine National Oil Company-Energy Development Corporation. The report is a review of an Acid Stimulation Treatment done on a production well in the Palinpinon I Geothermal Field. The report gives a detailed description of the key elements of the program as well as the end results. The report is divided into the following sections: (1) Introduction; (2) Key Elements of Stimulation; (3) Results; (4) Recommendations for Future Acid Treatments.

  7. Using micro-seismicity and seismic velocities to map subsurface geologic and hydrologic structure within the Coso geothermal field, California

    USGS Publications Warehouse

    Kaven, Joern Ole; Hickman, Stephen H.; Davatzes, Nicholas C.

    2012-01-01

    Geothermal reservoirs derive their capacity for fluid and heat transport in large part from faults and fractures. Micro-seismicity generated on such faults and fractures can be used to map larger fault structures as well as secondary fractures that add access to hot rock, fluid storage and recharge capacity necessary to have a sustainable geothermal resource. Additionally, inversion of seismic velocities from micro-seismicity permits imaging of regions subject to the combined effects of fracture density, fluid pressure and steam content, among other factors. We relocate 14 years of seismicity (1996-2009) in the Coso geothermal field using differential travel times and simultaneously invert for seismic velocities to improve our knowledge of the subsurface geologic and hydrologic structure. We utilize over 60,000 micro-seismic events using waveform cross-correlation to augment to expansive catalog of P- and S-wave differential travel times recorded at Coso. We further carry out rigorous uncertainty estimation and find that our results are precise to within 10s of meters of relative location error. We find that relocated micro-seismicity outlines prominent, through-going faults in the reservoir in some cases. We also find that a significant portion of seismicity remains diffuse and does not cluster into more sharply defined major structures. The seismic velocity structure reveals heterogeneous distributions of compressional (Vp) and shear (Vs) wave speed, with Vp generally lower in the main field when compared to the east flank and Vs varying more significantly in the shallow portions of the reservoir. The Vp/Vs ratio appears to outline the two main compartments of the reservoir at depths of -0.5 to 1.5 km (relative to sea-level), with a ridge of relatively high Vp/Vs separating the main field from the east flank. In the deeper portion of the reservoir this ridge is less prominent. Our results indicate that high-precision relocations of micro-seismicity can provide

  8. Faults dominant structure? -Seismic images of the subsurface structure for the Ilan geothermal field in Taiwan.

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Chun; Shih, Ruey-Chyuan; Wang, Chien-Ying; Kuo, Hsuan-Yu; Chen, Wen-Shan

    2016-04-01

    A prototype deep geothermal power plant is to be constructed at the Ilan plain in northeastern Taiwan. The site will be chosen from one of the two potential areas, one in the west and the other in the eastern side of the plain. The triangle-shaped Ilan plane is bounded by two mountain ranges at the northwest and the south, with argillite and slate outcrops exposed, respectively. The Ilan plane is believed situating in a structure extending area at the southwestern end of the Okinawa Trough. Many studies about subsurface structure of the plain have been conducted for years. The results showed that the thickest sediments, around 900 m, is located at the eastern coast of the plain, at north of the largest river in the plain, the Lanyang river, and then became shallower to the edges of the plain. Since the plane is covered by thick sediments, formations and structures beneath the sediments are barely known. However, the observed high geothermal gradient and the abundant hot spring in the Ilan area indicate that this area is having a high potential of geothermal energy. In order to build up a conceptual model for tracing the possible paths of geothermal water and search for a suitable site for the geothermal well, we used the seismic reflection method to delineate the subsurface structure. The seismic profiles showed a clear unconformity separating the sediments and the metamorphic bedrock, and some events dipping to the east in the bedrock. Seismic images above the unconformity are clear; however, seismic signals in the metamorphic bedrock are sort of ambiguous. There were two models interpreted by using around 10 seismic images that collected by us in the past 3 years by using two mini-vibrators (EnviroVibe) and a 360-channel seismic data acquisition system. In the first model, seismic signals in the bedrock were interpreted as layer boundaries, and a fractured metamorphic layer down the depth of 1200m was thought as the source of geothermal water reservoir. In the

  9. Thermal History of the Felsite Unit, Geysers Geothermal Field, From Thermal Modeling of 40Ar/39Ar Incremental Heating Data

    SciTech Connect

    T. M. Harrison; G. B. Dalrymple; J. B. Hulen; M. A. Lanphere; M. Grove; O. M. Lovera

    1999-08-19

    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.

  10. Geothermal pipeline

    SciTech Connect

    1997-08-01

    The Geothermal Pipeline is a progress and development update from the Geothermal Progress Monitor and includes brief descriptions of various geothermal projects around the world. The following topics are covered: The retirement of Geo-Heat Center Director Paul Lienau, announcement of two upcoming geothermal meetings, and a proposed geothermal power plant project in the Medicine Lake/Glass Mountain area of California. Also included is an article about the Bonneville Power Administration`s settlements with two California companies who had agreed to build geothermal power plants on the federal agency`s behalf, geothermal space heating projects and use of geothermal energy for raising red crayfish in Oregon, and some updates on geothermal projects in Minnesota, Pennsylvania, and China.

  11. The Significance of Acid Alteration in the Los Humeros High-Temperature Geothermal Field, Puebla, Mexico.

    NASA Astrophysics Data System (ADS)

    Elders, W. A.; Izquierdo, G.

    2014-12-01

    The Los Humeros geothermal field is a high-enthalpy hydrothermal system with more than 40 drilled deep wells, mostly producing high steam fractions at > 300oC. However, although it has a large resource potential, low permeability and corrosive acid fluids have hampered development so that it currently has an installed electrical generating capacity of only 40 MWe. The widespread production of low pH fluids from the reservoir is inconsistent with the marked absence in the reservoir rocks of hydrothermal minerals typical of acid alteration. Instead the hydrothermal alteration observed is typical of that due to neutral to alkaline pH waters reacting with the volcanic rocks of the production zones. Thus it appears that since the reservoir has recently suffered a marked drop in fluid pressure and is in process of transitioning from being water-dominated to being vapor-dominated. However sparse examples of acid leaching are observed locally at depths of about 2 km in the form of bleached, intensely silicified zones, in low permeability and very hot (>350oC) parts of reservoir. Although these leached rocks retain their primary volcanic and pyroclastic textures, they are altered almost entirely to microcrystalline quartz, with some relict pseudomorphs of plagioclase phenocrysts and traces of earlier-formed hydrothermal chlorite and pyrite. These acid-altered zones are usually only some tens of meters thick and deeper rocks lack such silicification. The acid fluids responsible for their formation could either be magmatic volatiles, or could be formed during production (e.g. reaction of water and salts forming hydrogen chloride by hydrolysis at high temperatures). The very high boron content of the fluids produced by the Los Humeros wells suggests that their ultimate source is most likely magmatic gases. However, these acid gases did not react widely with the rocks. We suggest that the silicified zones are forming locally where colder descending waters are encountering

  12. Volcanology and geothermal energy

    SciTech Connect

    Wohletz, K.; Heiken, G.

    1992-01-01

    The aim of this book is to demonstrate how volcanological concepts can be applied to the evaluation and exploration of geothermal energy resources. In regard to the geothermal content of the book, some of the information comes from the first-hand experience gained during the authors' exploration work in Middle America and with the Los Alamos Hot Dry Rock program. Other cases discussed come from classic geothermal systems in many regions and settings. The book begins with a summary of recent practical advances in volcanology, and then moves on to describe the considerable importance of pyroclastic rocks as a took to evaluate geothermal systems, including an in-depth treatment of hydrovolcanism. Following chapters deal with surface manifestations of geothermal systems, and systems associated with calderas, silicic lava domes, and basaltic volcanoes. The last chapter is on geothermal systems in maturing composite volcanoes. The Appendices include a broad overview of field methods in volcanic regions, volcanic rock classifications and properties, thermodynamic properties of water vapor (steam tables), and the use of cuttings in geothermal well logs. A two-dimensional heat flow code used for estimating geothermal resources is also given. The book makes two significant contributions: first, in its treatment of eruption dynamics, focusing on quantitative and theoretical analysis of volcanic processes, and second, in its comprehensive treatment of the fundamentals of hydrovolcanism, including fuel-coolant interactions and hydrofracturing.

  13. Advanced Geothermal Turbodrill

    SciTech Connect

    W. C. Maurer

    2000-05-01

    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.

  14. Investigation of a Seismic Swarm in the Krýsuvík Geothermal Field, SW Iceland

    NASA Astrophysics Data System (ADS)

    Liu, J.; Zhang, H.; Fehler, M. C.

    2012-12-01

    Iceland is an active part of the mid-ocean ridge system with active volcanism and near-surface thermal features, that are exploited for geothermal energy. The Krýsuvík region is one of the high temperature geothermal areas in the Reykjanes Peninsula in southwest Iceland that is an area of active interest for geothermal development. It is also an area that has experienced several swarms of seismicity and associated uplift. As part of a larger project to develop improved techniques for imaging geothermal fields using seismic and electromagnetic techniques, we have operated a seismic network on the Reykjanes Peninsula in collaboration with Uppsala University and Reykjavic University. During this deployment, we were fortunate to record a seismic swarm in the Krýsuvík region during which roughly thirty thousand earthquakes occurred. Combining data from our seismic network with that from 10 seismographs of the SIL (South Iceland Lowland) seismic network we are investigating the events that occurred during a swarm recorded between August 2010 and July 2011. The swarm was most active in February 2011. The seismicity occurred predominantly along a N-S trending fault, which is consistent with the results obtained from coseismic GPS displacements, and a NE-SW trending fault that is parallel to the plate boundary. This detailed map of subsurface fault directions is of great value for stress field evaluation in this area. Our next goal is to evaluate whether temporal velocity change accompanied the seismic swarm. This will be done using interferometry of ambient noise between station pairs. In this step, we will choose different station pairs that have a variety angels relative to the most active N-S trending fault to investigate the spatial and propagation-dependent velocity change along with its relation to results obtained by others from analysis of GPS data from the region. Finally, tomography calculated using TomoDD may give details of the spatial relation between

  15. Understanding the Chemical and Structural Dynamics of a Geothermal System Using Hyperspectral Imaging and Field Observations, Dixie Meadows, Nevada

    NASA Astrophysics Data System (ADS)

    Kennedy-Bowdoin, T. J.; Silver, E. A.; Martini, B. A.; Pickles, W. L.

    2003-12-01

    Dixie Valley hosts the largest geothermal plant in the state of Nevada. As part of an exploration program to evaluate other geothermal sites we mapped a 16 km swath of the eastern front of the Stillwater Range, including the Dixie Valley Fault system (Caskey et al. 1996) and Dixie Hot Springs. This visibly hydrothermally altered portion of the range front is located 25 km south of the existing plant and 10 km north of a major bend in the Dixie Valley Fault System. We used hyperspectral (HyMAP) data to locate outcrops of high temperature, hydrothermally altered minerals (including alunite, kaolinite, dickite, jarosite, and hematite). Several outcrops of these altered minerals exist in the mapped region, and one area of roughly 1 square kilometer shows abundant high temperature alteration. We also utilized an ASD field spectrometer to ground-truth our image interpretation and to map more subtle mineral distributions. These spectra support the locations of the mapped high temperature mineralization based on the hyperspectral data, and show that other high temperature minerals, such as vein chalcedony are present on scales below the spectral resolution of the HyMap data (3 m). At active fumaroles near the range front, acidic vapor-phase mineralization is occurring, and we measured ground temperatures of up to 94 §C. Approximately 1 km into the valley, at Dixie Valley Hot Springs, we measured alkaline liquid discharge to have a pH of 8.4 and a temperature of 75 §C. We also carried out structural analysis using a DEM, hyperspectral-based mineral mapping, and field observations. We find that this outcrop is bounded on all sides by a set of cross-cutting faults. We hypothesize that extension related to the release of the bend to the south has resulted in increased permeability, and as result, greater geothermal activity. Both the intense alteration in this area, including the presence of active fumeroles and hotsprings, and the high permeability introduced by cross

  16. Results From a Borehole Seismometer Array I: Microseismicity at a Productive Geothermal Field, Kilauea Lower East Rift Zone, Puna, Hawaii

    NASA Astrophysics Data System (ADS)

    Kenedi, C. L.; Shalev, E.; Malin, P.; Kaleikini, M.; Dahl, G.

    2008-12-01

    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

  17. Pressure responses of a geothermal doublet system: Field measurements and numerical simulations.

    NASA Astrophysics Data System (ADS)

    Blöcher, Guido; Zimmermann, Günter; Moeck, Inga; Brandt, Wulf; Hassanzadegan, Alireza; Huenges, Ernst

    2010-05-01

    This study addresses the hydro-thermal conditions of the geothermal research doublet E GrSk03/90 and Gt GrSk04/05 at the drill site Gross Schönebeck (north of Berlin, Germany). The prospected production well Gt GrSk04/05 with a true vertical depth of -4198 m has been finished in 2007, followed by three stimulation treatments to enhance productivity. At the top of the reservoir (-3815 m), the inclination of the production well is 18° and increases progressively to 48° at -4236 m. Therefore, the distance between the two wells increases from 241 to 470 m from top to bottom of the reservoir. The reservoir rocks are classified into two rock units from bottom to top: volcanic rocks (Lower Rotliegend) and siliciclastics (Upper Rotliegend) ranging from conglomerates to fine grained sand-, silt- and mudstones. The first stimulation treatment at the production well Gt GrSk04/05 in 2007 was applied in the low permeable volcanic rocks. During this stimulation a total volume of 13.000 m³ with maximum flow rates of 150 l/s was injected. The corresponding pressure change at the well head was 586 bars. Simultaneously, the well head pressure at the neighbouring well E GrSk03/90 increases by approx. 1 bar (0.17%). To confirm this direct pressure response, three impulse tests were performed in 2009. During these tests a total volume of 135 m³ with maximum flow rates of 3.6 l/s was produced from the well E GrSk03/90. The well head pressure decrease was 16 bars and the pressure response in the neighbouring well Gt GrSk04/05 was 0.025 bar (0.16%). Both, the stimulation treatment and the impulse test result in a direct pressure response in the neighbouring well and indicate a hydraulic interaction between both wells. This hydraulic interaction could be due to matrix flow and fluid flow in natural fracture and fault systems. In brittle crystalline or magmatic rocks, critically stressed faults are described as hydraulically transmissive due to a high fracture density in the fault

  18. Maximum Magnitude and Probabilities of Induced Earthquakes in California Geothermal Fields: Applications for a Science-Based Decision Framework

    NASA Astrophysics Data System (ADS)

    Weiser, Deborah Anne

    Induced seismicity is occurring at increasing rates around the country. Brodsky and Lajoie (2013) and others have recognized anthropogenic quakes at a few geothermal fields in California. I use three techniques to assess if there are induced earthquakes in California geothermal fields; there are three sites with clear induced seismicity: Brawley, The Geysers, and Salton Sea. Moderate to strong evidence is found at Casa Diablo, Coso, East Mesa, and Susanville. Little to no evidence is found for Heber and Wendel. I develop a set of tools to reduce or cope with the risk imposed by these earthquakes, and also to address uncertainties through simulations. I test if an earthquake catalog may be bounded by an upper magnitude limit. I address whether the earthquake record during pumping time is consistent with the past earthquake record, or if injection can explain all or some of the earthquakes. I also present ways to assess the probability of future earthquake occurrence based on past records. I summarize current legislation for eight states where induced earthquakes are of concern. Unlike tectonic earthquakes, the hazard from induced earthquakes has the potential to be modified. I discuss direct and indirect mitigation practices. I present a framework with scientific and communication techniques for assessing uncertainty, ultimately allowing more informed decisions to be made.

  19. Inversion of Synthetic Aperture Radar Interferograms for Sources of Production-Related Subsidence at the Dixie Valley Geothermal Field

    SciTech Connect

    Foxall, W; Vasco, D

    2003-02-07

    We used synthetic aperture radar interferograms to image ground subsidence that occurred over the Dixie Valley geothermal field during different time intervals between 1992 and 1997. Linear elastic inversion of the subsidence that occurred between April, 1996 and March, 1997 revealed that the dominant sources of deformation during this time period were large changes in fluid volumes at shallow depths within the valley fill above the reservoir. The distributions of subsidence and subsurface volume change support a model in which reduction in pressure and volume of hot water discharging into the valley fill from localized upflow along the Stillwater range frontal fault is caused by drawdown within the upflow zone resulting from geothermal production. Our results also suggest that an additional source of fluid volume reduction in the shallow valley fill might be similar drawdown within piedmont fault zones. Shallow groundwater flow in the vicinity of the field appears to be controlled on the NW by a mapped fault and to the SW by a lineament of as yet unknown origin.

  20. The structure of the shallow crust beneath Olkaria geothermal field, Kenya, deduced from gravity studies

    NASA Astrophysics Data System (ADS)

    Ndombi, J. M.

    1981-02-01

    The Olkaria region of the Kenya rift valley is a potentially important geothermal area due to the occurrence of young volcanic activity and surface geothermal manifestations which include hot springs, fumaroles and thermally altered ground. In order to determine subsurface structure nearly 255 new gravity measurements, together with existing regional gravity data, were used to propose a subsurface model. A few surface density measurements have been made within Olkaria and in adjoining areas, and these combined with density values inferred from the measured P-wave seismic velocities within Olkaria are used to define the density distribution within the shallow crust. A two-dimensional model to explain the local gravity anomalies indicates that an approximately horizontal three-layer volcanic sequence overlying the basement system is downfaulted on the western part of Olkaria, and is intruded by denser dyke-like bodies of rhyolitic composition along the north-south-trending fractures that occur mainly in the central part of the Olkaria. An increase in the thickness of volcanics in the western part of Olkaria is responsible for the observed negative Bouguer anomaly in that area, while vertical density contrasts between the dyke-like intrusions and the host rock generate model anomalies in good agreement with the observed positive Bouguer anomalies in the central part of Olkaria. The largest and most recent intrusion, which is probably still in a magmatic state, occurs along the Ololbutot fracture zone and is apparently the main heat source for the geothermal phenomena in Olkaria.

  1. Human Resources in Geothermal Development

    SciTech Connect

    Fridleifsson, I.B.

    1995-01-01

    Some 80 countries are potentially interested in geothermal energy development, and about 50 have quantifiable geothermal utilization at present. Electricity is produced from geothermal in 21 countries (total 38 TWh/a) and direct application is recorded in 35 countries (34 TWh/a). Geothermal electricity production is equally common in industrialized and developing countries, but plays a more important role in the developing countries. Apart from China, direct use is mainly in the industrialized countries and Central and East Europe. There is a surplus of trained geothermal manpower in many industrialized countries. Most of the developing countries as well as Central and East Europe countries still lack trained manpower. The Philippines (PNOC) have demonstrated how a nation can build up a strong geothermal workforce in an exemplary way. Data from Iceland shows how the geothermal manpower needs of a country gradually change from the exploration and field development to monitoring and operations.

  2. Relation of compositions of deep fluids in geothermal activity of Pleistocene-Holocene volcanic fields of Lesser Caucasus

    NASA Astrophysics Data System (ADS)

    Meliksetian, Khachatur; Lavrushin, Vassily; Shahinyan, Hrach; Aidarkozhina, Altin; Navasardyan, Gevorg; Ermakov, Alexander; Zakaryan, Shushan; Prasolov, Edward; Manucharyan, Davit; Gyulnazaryan, Shushan; Grigoryan, Edmond

    2017-04-01

    It is widely accepted, that geothermal activity in the conductive heat flow processes, such as volcanism and hydrothermal activity, is manifestation of the thermal mass transfer process in the Earth's crust, where geothermal and geochemical processes are closely connected. Therefore, geochemistry and isotope compositions of thermal mineral waters within and on periphery of volcanic clusters may represent key indicators for better understanding of geothermal activity in geodynamically active zones. Geochemical features of heat and mass transport in hydrothermal systems related to active volcanic and fault systems in continental collision related orogenic elevated plateaus such as Anatolian-Armenian-Iranian highlands are still poorly understood. In this contribution we attempt to fill these gaps in our knowledge of relations of geochemical and geothermal processes in collision zones. We present new data on chemical compositions, trace element geochemistry of thermal waters of Lesser Caucasus, (Armenia) as well as isotope analysis of free gases such as {}3He/{}4He, {}40Ar/{}36Ar, δ{}13?(CO{}2), nitrogen δ{}15N(N{}2) and oxygen and hydrogen isotopes in water phases (δD, δ{}18O). To reveal some specific features of formation of fluid systems related to thermal activity in the areas of collision related active volcanism and active geodynamics a complex geochemical (SiO{}2, K-Na, Na-Li, Li-Mg) and isotope geothermometers (δ{}18O(CaCO{}3) - δ{}18O(H{}2O)) were applied. The distribution of δ{}13?(??{}2) values in free gases of mineral waters of Armenia demonstrates that gases related to Quaternary volcanic fields are characterized by relatively light δ{}13?(CO{}2) values close to mantle derived gases, while on periphery of volcanic systems relatively heavy values of δ{}13?(CO{}2) indicate strong influence of metamorphic and sedimentary derived carbon dioxide. Distribution of nitrogen isotopes δ{}15N(N{}2) demonstrate an inverse correlation with δ{}13?(CO{}2

  3. Microseismicity in the Ngatamariki Geothermal Field, Taupo Volcanic Zone, New Zealand: Determination and Application of a Matched-Filter Threshold

    NASA Astrophysics Data System (ADS)

    Matson, G. O.; Savage, M. K.; Townend, J.

    2015-12-01

    The high-temperature, fluid-dominated Ngatamariki geothermal field is located in the central Taupo Volcanic Zone (TVZ), North Island, New Zealand, and is used to generate electricity via an 82 MW power plant. Injection wells have been in operation since June 2012. Geothermal stimulation and production may trigger microearthquakes by fluid flow through the reservoir. Close clustering of microseismic events' hypocentres relative to the source-receiver distance results in many events having similar waveforms. We capitalize on this using a matched-filter detection method in which high-quality seismograms corresponding to a well-recorded earthquake ("templates") are cross-correlated against continuous data to reveal additional earthquakes with similar characteristics. As in matched-filter detection studies elsewhere, we require that the sum of correlation coefficients across the network exceed a noise-based threshold in order to recognise a detection. The threshold is defined by R×MAD, where R is a scalar coefficient and MAD is the median absolute deviation of the correlation coefficient sum throughout the day. The R coefficient is a function of the recording environment, network geometry and time-varying noise characteristics, and we estimate it empirically using synthetic testing. By seeding the continuous data with scaled versions of representative templates, we examine how the amplitudes of detectable events are compared with correlation and detection efficiency. Synthetic testing yields a threshold for this geothermal region of R=7.1. Using this threshold, events with amplitudes as small as ~2% of the original templates' amplitudes are detected with 95% confidence. The matched filter detection of microseismic events allows further interpretation of geologic structure at Ngatamariki and of the relationship between production, injection and seismicity.

  4. Improving the Curie depth estimation through optimizing the spectral block dimensions of the aeromagnetic data in the Sabalan geothermal field

    NASA Astrophysics Data System (ADS)

    Akbar, Somaieh; Fathianpour, Nader

    2016-12-01

    The Curie point depth is of great importance in characterizing geothermal resources. In this study, the Curie iso-depth map was provided using the well-known method of dividing the aeromagnetic dataset into overlapping blocks and analyzing the power spectral density of each block separately. Determining the optimum block dimension is vital in improving the resolution and accuracy of estimating Curie point depth. To investigate the relation between the optimal block size and power spectral density, a forward magnetic modeling was implemented on an artificial prismatic body with specified characteristics. The top, centroid, and bottom depths of the body were estimated by the spectral analysis method for different block dimensions. The result showed that the optimal block size could be considered as the smallest possible block size whose corresponding power spectrum represents an absolute maximum in small wavenumbers. The Curie depth map of the Sabalan geothermal field and its surrounding areas, in the northwestern Iran, was produced using a grid of 37 blocks with different dimensions from 10 × 10 to 50 × 50 km2, which showed at least 50% overlapping with adjacent blocks. The Curie point depth was estimated in the range of 5 to 21 km. The promising areas with the Curie point depths less than 8.5 km are located around Mountain Sabalan encompassing more than 90% of known geothermal resources in the study area. Moreover, the Curie point depth estimated by the improved spectral analysis is in good agreement with the depth calculated from the thermal gradient data measured in one of the exploratory wells in the region.

  5. Geothermal Energy.

    ERIC Educational Resources Information Center

    Reed, Marshall J.

    1979-01-01

    During 1978, exploration for geothermal energy continued at the same moderately low level of the past few years in most countries. The U.S. is the only country where the development of geothermal energy depends on private industry. (BB)

  6. Geothermal Energy.

    ERIC Educational Resources Information Center

    Reed, Marshall J.

    1979-01-01

    During 1978, exploration for geothermal energy continued at the same moderately low level of the past few years in most countries. The U.S. is the only country where the development of geothermal energy depends on private industry. (BB)

  7. Geothermal Energy

    SciTech Connect

    Steele, B.C.; Harman, G.; Pitsenbarger, J.

    1996-02-01

    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.

  8. Reactive geothermal transport simulation to study the formation mechanism of impermeable barrier between acidic and neutral fluid zones in the Onikobe Geothermal Field, Japan

    SciTech Connect

    Todaka, Norifumi; Akasaka, Chitosi; Xu, Tianfu; Pruess, Karsten

    2003-04-09

    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.

  9. Geothermal systems

    NASA Technical Reports Server (NTRS)

    Mohl, C.

    1978-01-01

    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.

  10. Geothermal systems

    NASA Technical Reports Server (NTRS)

    Mohl, C.

    1978-01-01

    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.

  11. Idaho Geothermal Commercialization Program. Idaho geothermal handbook

    SciTech Connect

    Hammer, G.D.; Esposito, L.; Montgomery, M.

    1980-03-01

    The following topics are covered: geothermal resources in Idaho, market assessment, community needs assessment, geothermal leasing procedures for private lands, Idaho state geothermal leasing procedures - state lands, federal geothermal leasing procedures - federal lands, environmental and regulatory processes, local government regulations, geothermal exploration, geothermal drilling, government funding, private funding, state and federal government assistance programs, and geothermal legislation. (MHR)

  12. Differentiating induced and natural seismicity using space-time-magnitude statistics applied to the Coso Geothermal field

    USGS Publications Warehouse

    Schoenball, Martin; Davatzes, Nicholas C.; Glen, Jonathan M. G.

    2015-01-01

    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. We study natural and induced earthquakes comparatively in the same tectonic setting at the Coso Geothermal Field. Covering the preproduction and coproduction periods from 1981 to 2013, we analyze interevent 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 clear differences between both kinds of seismicity. Compared to natural earthquakes, induced earthquakes feature a larger population of background seismicity and nearest neighbors at large magnitude rescaled times and small magnitude rescaled distances. Local stress perturbations induced by field operations appear to be strong enough to drive local faults through several seismic cycles and reactivate them after time periods on the order of a year.

  13. Geothermal Energy.

    ERIC Educational Resources Information Center

    Bufe, Charles Glenn

    1983-01-01

    Major activities, programs, and conferences in geothermal energy during 1982 are highlighted. These include first comprehensive national assessment of U.S. low-temperature geothermal resources (conducted by U.S. Geological Survey and Department of Energy), map production by U.S. Geological Survey, geothermal plant production, and others. (JN)

  14. Geothermal Energy.

    ERIC Educational Resources Information Center

    Bufe, Charles Glenn

    1983-01-01

    Major activities, programs, and conferences in geothermal energy during 1982 are highlighted. These include first comprehensive national assessment of U.S. low-temperature geothermal resources (conducted by U.S. Geological Survey and Department of Energy), map production by U.S. Geological Survey, geothermal plant production, and others. (JN)

  15. Uranium-thorium series radionuclides in brines and reservoir rocks from two deep geothermal boreholes in the Salton Sea Geothermal Field, southeastern California

    NASA Astrophysics Data System (ADS)

    Zukin, Jeffrey G.; Hammond, Douglas E.; Teh-Lung, Ku; Elders, Wilfred A.

    1987-10-01

    Naturally occurring U and Th series radionuclides have been analyzed in high temperature brines (~300°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. Rock/Brine concentration ratios ( Rc = (dpm/ g) rock/(dpm/ g) brine) were found to vary from near unity for isotopes of Ra, Pb and Rn to about 5 × 10 5 for 232Th. The high sorptivity of 232Th is closely followed by that of 238U and 234U ( Rc ~ 5 × 10 4), suggesting that U is retained in the +4 oxidation state by the reducing conditions in the brines. The relatively high solubility of 210Pb and 212Pb is attributed to formation of chloride complexes, while the high Ra solubility is attributed to chloride complexing, a lack of suitable adsorption sites due to the high brine salinity and temperature, and the reducing conditions that prevent MnO 2 and RaSO 4 from forming. The 228Ra /226Ra ratios in the brines are approximately equal to those of their parents ( 232Th /230Th ) in associated rocks, indicating that Ra equilibration in the brine-rock system is achieved within the mean life of 228Ra (8.3 years). The 224Ra /228Ra ratios in these brines are about 0.7, indicating that either (1) brine composition is not homogeneous and 224Ra decays in fracture zones deficient in Ra and Th as the brine travels to the wellhead or (2) Ra equilibration in the brine-host rock system is not complete within the mean life of 224Ra (5.2 days) because the desorption of 224Ra from the solid phase is impeded. The 228Ac /228Ra activity ratio in the SSGF brines studied is <0.1, and from this ratio the residence time of 228Ac in the brine before sorption onto solid surfaces is estimated to be <70

  16. Time-series analysis of surface deformation at Brady Hot Springs geothermal field (Nevada) using interferometric synthetic aperture radar

    SciTech Connect

    Ali, S. T.; Akerley, J.; Baluyut, E. C.; Cardiff, M.; Davatzes, N. C.; Feigl, K. L.; Foxall, W.; Fratta, D.; Mellors, R. J.; Spielman, P.; Wang, H. F.; Zemach, E.

    2016-05-01

    We analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014, by the ERS-2, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada due to extraction of fluids. The long axis of the ~4 km by ~1.5 km elliptical subsiding area coincides with the strike of the dominant normal fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. This signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. Results from inverse modeling suggest that the deformation is a result of volumetric contraction in shallow units, no deeper than 600 m, likely associated with damaged regions where fault segments mechanically interact. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing a high permeability conduit to the production wells. Using time series analysis, we test the hypothesis that geothermal production drives the observed deformation. We find a good correlation between the observed deformation rate and the rate of production in the shallow wells. We also explore mechanisms that could potentially cause the observed deformation, including thermal contraction of rock, decline in pore pressure and dissolution of minerals over time.

  17. Direct utilization of geothermal resources field experiments at Monroe, Utah. Final report, July 14, 1978-July 13, 1981

    SciTech Connect

    Blair, C.K.; Owen, L.B.

    1982-12-01

    The City of Monroe, Utah undertook a project to demonstrate the economic and technical viability of utilizing a low temperature geothermal resource to provide space and hot water heating to commercial, municipal, and domestic users within the community. During the course of the project, resource development and assessment, including drilling of a production well, was successfully completed. Upon completion of the field development and assessment phase of the program and of a preliminary design of the district heating system, it was determined that the project as proposed was not economically viable. This was due to: (1) a significant increase in estimated capital equipment costs resulting from the general inflation in construction costs, the large area/low population density in Monroe, and a more remote fluid disposal well site than planned, could not balance increased construction costs, (2) a lower temperature resource than predicted, and (3) due to predicted higher pumping and operating costs. After a thorough investigation of alternatives for utilizing the resource, further project activities were cancelled because the project was no longer economical and an alternative application for the resource could not be found within the constraints of the project. The City of Monroe, Utah is still seeking a beneficial use for the 600 gpm, 164/sup 0/F geothermal well. A summary of project activities included.

  18. Deformation at Brady Hot Springs (Nevada) geothermal field measured by time series analysis of InSAR data

    NASA Astrophysics Data System (ADS)

    Ali, S. T.; Davatzes, N. C.; Feigl, K. L.; Wang, H. F.; Foxall, W.; Mellors, R. J.; Akerley, J.; Spielman, P.; Zemach, E.

    2014-12-01

    We analyze interferometric synthetic aperture radar (InSAR) data acquired between 1997 and 2014 (by the ERS, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions) to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in Western Nevada due to net extraction of fluids. The long axis of the ~4 km by ~1.5 km oval shaped subsiding region coincides with the strike of the predominant normal fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. These smaller features are spatially associated with the intersections and overlaps of some of the mapped fault segments. This type of signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. To model the deformation, we explore several different observable quantities, including the spatial derivative of the range change (dimensionless), and the (unwrapped) range change (in mm). The results from inverse modeling suggest that the deformation is a result of compaction associated with a decline in pore-fluid pressure. This phenomenon occurs in shallow lithologic units and/or highly damaged regions where fault segments mechanically interact. Such damaged zones are expected to be vertically extensive along the faults, providing a high permeability conduit to the deep reservoir tapped by production wells. Using time series analysis, we test the hypothesis that changes in the net rate of geothermal production drive the observed deformation.

  19. Fifteenth workshop on geothermal reservoir engineering: Proceedings

    SciTech Connect

    Not Available

    1990-01-01

    The Fifteenth Workshop on Geothermal Reservoir Engineering was held at Stanford University on January 23--25, 1990. Major topics included: DOE's geothermal research and development program, well testing, field studies, geosciences, geysers, reinjection, tracers, geochemistry, and modeling.

  20. Silica phases in sinters and residues from geothermal fields of New Zealand

    NASA Astrophysics Data System (ADS)

    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.

    2004-06-01

    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

  1. Seismic tremor and gravity measurements at Inferno Crater Lake, Waimangu Geothermal Field, New Zealand

    NASA Astrophysics Data System (ADS)

    O'Brien, J. F.; Jolly, A. D.; Fournier, N.; Cole-Baker, J.; Hurst, T.; Roman, D. C.

    2011-12-01

    Volcanic crater lakes are often associated with active hydrothermal systems that induce cyclic behavior in the lake's level, temperature, and chemistry. Inferno Crater Lake, located in the Waimangu geothermal field within the Taupo Volcanic Zone (TVZ) on the North Island of New Zealand exhibits lake level fluctuations of >7m, and temperature fluctuations >40°C with a highly variable periodicity. Seismic and gravity monitoring of Inferno Lake was carried out from December, 2009 - March, 2010 and captured a full cycle of lake fluctuation. Results indicate that this cycle consisted of ~5 smaller fluctuations of ~3m in lake level followed by a larger fluctuation of ~7m. A broadband seismometer recorded strong seismic tremor in the hours leading up to each of the minor and major high stands in lake level. Spectral analysis of the tremor shows dominant frequencies in the range of ~10Hz and a fundamental harmonic frequency located in the 1Hz range. The 1Hz frequency band exhibits gliding spectral lines which increase in frequency at the end of each tremor period. Particle motion analysis of harmonic tremor waveforms indicate a ~100m upward migration of the source location from the onset of tremor until it ceases at the peak of each lake level high stand. Particle motions also indicate an azimuthal migration of the source by ~30° from the overflow outlet region of the lake toward the central vent location during the course of the tremor and lake level increase. Lake water temperature has a direct relationship with lake level and ranges between ~40°C - ~80°C. Gravity fluctuations were also continuously monitored using a Micro-g-LaCoste gPhone relative gravity meter with a 1Hz sampling rate and precision of 1 microgal. These data indicate a direct relationship between lake level and gravity showing a net increase of ~100 microgals between lake level low and high stands. A piezometer located beside the lake indicates an inflow of ground water into the subsoil during

  2. Relationship of geological and geothermal field properties: Midcontinent area, USA, an example

    USGS Publications Warehouse

    Forster, A.; Merriam, D.F.; Brower, J.C.

    1993-01-01

    Quantitative approaches to data analysis in the last decade have become important in basin modeling and mineral-resource estimation. The interrelation of geological, geophysical, geochemical, and geohydrological variables is important in adjusting a model to a real-world situation. Revealing the interdependences of variables can contribute in understanding the processes interacting in sedimentary basins. It is reasonably simple to compare spatial data of the same type but more difficult if different properties are involved. Statistical techniques, such as cluster analysis or principal components analysis, or some algebraic approaches can be used to ascertain the relations of standardized spatial data. In this example, structural configuration on five different stratigraphic horizons, one total sediment thickness map, and four maps of geothermal data were copared. As expected, the structural maps are highly related because all had undergone about the same deformation with differing degrees of intensity. The temperature gradients derived (1) from shallow borehole logging measurements under equilibrium conditions with the surrounding rock, and (2) from non-equilibrium bottom-hole temperatures (BHT) from deeper depths are mainly independent of each other. This was expected and confirmed also for the two temperature maps at 1000 ft which were constructed using both types of gradient values. Thus, it is evident that the use of a 2-point (BHT and surface temperature) straightline calculation of a mean temperature gradient gives different information about the geothermal regime than using gradients from temperatures logged under equilibrium conditions. Nevertheless, it is useful to determine to what a degree the larger dataset of nonequilibrium temperatures could reflect quantitative relationships to geologic conditions. Comparing all maps of geothermal information vs. the structural and the sediment thickness maps, it was determined that all correlations are moderately

  3. Field tests of corrosion and chemical sensors for geothermal power plants

    SciTech Connect

    Robertus, R.J.; Shannon, D.W.; Sullivan, R.G.; Mackey, D.B.; Koski, O.H.; McBarron, F.O.; Duce, J.L.; Pierce, D.D.

    1986-03-01

    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.

  4. Geothermal reservoir technology

    SciTech Connect

    Lippmann, M.J.

    1985-09-01

    A status report on Lawrence Berkeley Laboratory's Reservoir Technology projects under DOE's Hydrothermal Research Subprogram is presented. During FY 1985 significant accomplishments were made in developing and evaluating methods for (1) describing geothermal systems and processes; (2) predicting reservoir changes; (3) mapping faults and fractures; and (4) field data analysis. In addition, LBL assisted DOE in establishing the research needs of the geothermal industry in the area of Reservoir Technology. 15 refs., 5 figs.

  5. Land subsidence in the Cerro Prieto Geothermal Field, 1 Baja California, Mexico, from 1994 to 2005. An integrated analysis of DInSAR, levelingand geological data.

    SciTech Connect

    Sarychikhina, O; Glowacka, E; Mellors, R; Vidal, F S

    2011-03-03

    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.

  6. Land subsidence in the Cerro Prieto Geothermal Field, Baja California, Mexico, from 1994 to 2005: An integrated analysis of DInSAR, leveling and geological data

    NASA Astrophysics Data System (ADS)

    Sarychikhina, Olga; Glowacka, Ewa; Mellors, Robert; Vidal, Francisco Suárez

    2011-07-01

    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 the local 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 understanding of the 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 changes in spatial pattern and rate of the subsidence are correlated with the development of the Cerro Prieto Geothermal Field.

  7. Stress field respond to massive injection of cold water into a geothermal reservoir study by geomechanical simulation

    NASA Astrophysics Data System (ADS)

    Jeanne, P.; Rutqvist, J.

    2015-12-01

    In this paper, we study the evolution and distribution of the stress tensor within the northwest part of The Geysers geothermal field during 9 years of injection (from 2003 to 2012). Based on a refined 3D structural model, developed by Calpine Corporation, where the horizon surfaces are mapped, we use the GMS™ GUI to construct a realistic three-dimensional geologic model of the Northwest Geysers geothermal field. This model includes a low permeability graywacke layer that forms the caprock for the reservoir, an isothermal steam zone (the Normal Temperature Reservoir) within metagraywacke, a hornfels zone (the High Temperature Reservoir), and a felsite layer that is assumed to extend downward to the magmatic heat source. This model is mapped into a rectangular grid for use with the TOUGH-FLAC numerical simulator. Then, we reproduce the injection history of seven active wells between 2003 and 2012. Finally, our results are compared with previous works where the stress tensor was studied from the inversion of focal plane mechanism in the same area and during the same period. As in these publications we find that: (1) changes in the orientation of principal horizontal stress are very small after one decade of injection, and (2) at injection depth significant rotations of the initially vertically oriented maximum compressive principal stress occur in response to changes in the fluid injection rates. As observed in the field, we found that σ1 tilted towards the σ2 direction by approximately 15° when injection rates were at their peak level. Such a rotation consequently results in a local change in the state stress from a normal stress regime (Sv > SHmax> > Shmin) to a strike slip regime (SHmax> Sv > > Shmin) above and below the injection zone. Our results show that thermal processes are the principal cause for the stress tensor rotation.

  8. Geology of the Pavana geothermal area, Departamento de Choluteca, Honduras, Central America: Field report

    SciTech Connect

    Eppler, D.B.; Heiken, G.; Wohletz, K.; Flores, W.; Paredes, J.R.; Duffield, W.A.

    1987-09-01

    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.

  9. Directly imaging steeply-dipping fault zones in geothermal fields with multicomponent seismic data

    DOE PAGES

    Chen, Ting; Huang, Lianjie

    2015-07-30

    For characterizing geothermal systems, it is important to have clear images of steeply-dipping fault zones because they may confine the boundaries of geothermal reservoirs and influence hydrothermal flow. Elastic reverse-time migration (ERTM) is the most promising tool for subsurface imaging with multicomponent seismic data. However, conventional ERTM usually generates significant artifacts caused by the cross correlation of undesired wavefields and the polarity reversal of shear waves. In addition, it is difficult for conventional ERTM to directly image steeply-dipping fault zones. We develop a new ERTM imaging method in this paper to reduce these artifacts and directly image steeply-dipping fault zones.more » In our new ERTM method, forward-propagated source wavefields and backward-propagated receiver wavefields are decomposed into compressional (P) and shear (S) components. Furthermore, each component of these wavefields is separated into left- and right-going, or downgoing and upgoing waves. The cross correlation imaging condition is applied to the separated wavefields along opposite propagation directions. For converted waves (P-to-S or S-to-P), the polarity correction is applied to the separated wavefields based on the analysis of Poynting vectors. Numerical imaging examples of synthetic seismic data demonstrate that our new ERTM method produces high-resolution images of steeply-dipping fault zones.« less

  10. Directly imaging steeply-dipping fault zones in geothermal fields with multicomponent seismic data

    SciTech Connect

    Chen, Ting; Huang, Lianjie

    2015-07-30

    For characterizing geothermal systems, it is important to have clear images of steeply-dipping fault zones because they may confine the boundaries of geothermal reservoirs and influence hydrothermal flow. Elastic reverse-time migration (ERTM) is the most promising tool for subsurface imaging with multicomponent seismic data. However, conventional ERTM usually generates significant artifacts caused by the cross correlation of undesired wavefields and the polarity reversal of shear waves. In addition, it is difficult for conventional ERTM to directly image steeply-dipping fault zones. We develop a new ERTM imaging method in this paper to reduce these artifacts and directly image steeply-dipping fault zones. In our new ERTM method, forward-propagated source wavefields and backward-propagated receiver wavefields are decomposed into compressional (P) and shear (S) components. Furthermore, each component of these wavefields is separated into left- and right-going, or downgoing and upgoing waves. The cross correlation imaging condition is applied to the separated wavefields along opposite propagation directions. For converted waves (P-to-S or S-to-P), the polarity correction is applied to the separated wavefields based on the analysis of Poynting vectors. Numerical imaging examples of synthetic seismic data demonstrate that our new ERTM method produces high-resolution images of steeply-dipping fault zones.

  11. Geothermal test hints at oil potential in eastern Arizona volcanic field

    SciTech Connect

    Rauzi, S.L. )

    1993-01-03

    A recently drilled geothermal well, funded by the US Department of Energy and the Arizona Department of Commerce, has provided information about the geology of east-central Arizona and west-central New Mexico. Tonto Drilling Services in cooperation with New Mexico State University completed the well, the 1 Alpine-Federal, at a total depth of 4,505 ft. The well is located among volcanic rocks in the Apache-Sitgreaves National Forest about 6 miles north of the town of Alpine and 6.2 miles west of the Arizona-New Mexico line. The well was drilled to determine the hot dry rock geothermal potential of Precambrian rocks. The operator expected to penetrate Precambrian at about 4,200 ft, but the hole was still in Permian rocks at that depth and was in a mafic dike that intruded the Permian rocks at the total depth of 4,505 ft. The hole did show that Cretaceous and Permian strata contain potentially important source rocks for oil and gas that are apparently unaffected by nearby volcanism. These potential oil source rocks are the focus of this article.

  12. Evaluation of the solute geothermometry of thermal springs and drilled wells of La Primavera (Cerritos Colorados) geothermal field, Mexico: A geochemometrics approach

    NASA Astrophysics Data System (ADS)

    Pandarinath, Kailasa; Domínguez-Domínguez, Humberto

    2015-10-01

    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

  13. Results of investigation at the Ahuachapan Geothermal Field, El Salvador. Part 2, Electrical-methods geophysics: Final report

    SciTech Connect

    Fink, J.B.

    1990-04-01

    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.

  14. Permeability enhancement due to cold water injection: A Case Study at the Los Azufres Geothermal Field, Mexico

    SciTech Connect

    Benson, S.M.; Daggett, J.; Ortiz, J.; Iglesias, E.; Comision Federal de Electricidad, Morelia; Instituto de Investigaciones Electricas, Cuernavaca )

    1989-04-01

    Pressure transient buildup and falloff data from 3 wells at the Los Azufres geothermal field have been evaluated to determine the extent to which cold water infection increases the permeability of the near-bore reservoir formation. Simultaneous analysis of the buildup and falloff data provides estimates of the permeability-thickness of the reservoir, the skin factor of the well, and the degree of permeability enhancement in the region behind the thermal front. Estimates of permeability enhancement range from a factor of 4 to 9, for a temperature change of about 150{degree}C. The permeability enhancement is attributed to thermally induced contraction and stress-cracking of the formation. 9 refs., 18 figs.

  15. Geodetic Measurements and Numerical Modeling of Deformation at Raft River Geothermal Field, Idaho, U.S.A.

    NASA Astrophysics Data System (ADS)

    Ali, S. T.; Feigl, K. L.; Moore, J.; Plummer, M. A.; Warren, I.

    2015-12-01

    To measure time-dependent deformation at the Raft River geothermal field in Cassia County in Southwestern Idaho, we analyze interferometric synthetic aperture radar (InSAR) data acquired between 2006 and 2015 by several satellite missions, including: Envisat, ALOS, TerraSAR-X, and TanDEM-X. The resulting time-series analysis indicates that the deformation began in late 2007, shortly after a 13-megawatt geothermal power plant began commercial production. The rate of deformation appears to be decreasing over time since 2008. The resulting maps of deformation show primarily uplift with some subsidence. The uplift signal is located in an ~8-km-by-5-km area centered near three injection wells that recycle produced brine into the Salt Lake formation, which consists of Miocene-Pliocene lacustrine deposits, volcanic tuffs, and lava flows. Subsidence occurs in an adjacent ~4-km-by-4-km area to the northwest. These two signatures remain in the same location in all of the well-correlated interferometric pairs since 2008. Although all production wells are also located inside the area experiencing uplift, most of them are close to the boundary that separates the two areas, and likely associated with the steeply dipping Bridge Fault zone. We explore the relative roles of thermal (T), and hydrological (H) processes on mechanical deformation (M). To do so, we use finite element based numerical models to calculate the time-dependent deformation field due to thermal contraction/expansion of rock (T-M coupling), and changes in pore pressure (H-M coupling).

  16. The carbonate rock-hosted epithermal gold deposit of Agdarreh, Takab geothermal field, NW Iran—hydrothermal alteration and mineralisation

    NASA Astrophysics Data System (ADS)

    Daliran, Farahnaz

    2008-06-01

    The disseminated gold deposit of Agdarreh (24.5 t at 3.7 g/t Au) is hosted in hydrothermally leached Miocene reefal limestone in the Takab geothermal field, which is part of the Cenozoic Urumieh-Dokhtar volcanic arc of NW Iran. Alteration and mineralisation are largely bedding controlled blanket-like and include: (1) pre-ore decalcification; (2) first-stage silicification associated with pyrite (early pyrite with 3-4 wt% As, late pyrite with <1-3 wt% As) and sphalerite; (3) second-stage silicification with precipitation of galena, Pb-Sb-As sulphides, sulphosalts, tellurides and native bismuth; (4) late-stage cinnabar and barite in vugs; (5) oxide ore stage and carbonate alteration (complex Mn-Fe-rich oxyhydroxides, arsenates, sulphates, APS minerals and rutile in residual leached rock and infill of karstic cavities). Gold occurs invisibly in the jasperoids and is enriched in the Mn-Fe oxyhydroxide surface cap of the jasperoids. Gold mineralisation is associated with the hydrothermal metal suite of As, Sb, Hg, Te, Se, Tl, Ba, Zn, Ag, Cd, Bi and Pb, and is characterised by very low Cu contents. Arsenian pyrite probably carried most of the primary (invisible) gold. Native gold occurs in association with the late-stage cinnabar and the oxide ore. The Agdarreh deposit shows many similarities with Carlin-type ore and is interpreted to have resulted from near-surface hydrothermal activity related to the Cenozoic arc volcanism that developed within the extensional Takab graben. The extensive oxidation at Agdarreh may be partly due to the waning stages of hydrothermal activity. Active H2S-bearing thermal springs are locally depositing extremely high contents of Au and Ag, and travertine is present over large areas, suggesting that ore-forming hydrothermal activity occurred periodically from the Miocene to Recent in the Takab geothermal field.

  17. Fracture Development within the Karaha-Telaga Bodas Geothermal Field, Indonesia

    USGS Publications Warehouse

    Nemcok, M.; Moore, J.N.; Allis, R.; McCulloch, J.

    2002-01-01

    Karaha-Telaga Bodas is a partially vapor-dominated geothermal system located in an active volcano in western Java. More than 2 dozen geothermal wells have been drilled to depths of 3 km. Detailed paragenetic and fluid-inclusion studies have defined liquid-dominated, transitional and vapor-dominated stages in the evolution of this system. The liquid-dominated stage was initiated by shallow 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 were filled with carbonates at shallow depths and by quartz, epidote and actinolite at depths and temperatures over 1km and 300??C. The system underwent numerous local cycles of overpressuring, which are marked by subhorizontal tensile fractures, anastomosing tensile fractures and implosion breccias. The development of the liquid system was interrupted by a catastrophic drop in fluid pressures. As the fluids boiled in response to this pressure drop, chalcedony and quartz were deposited in fractures having 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. Vapor-dominated conditions were initiated within a vertical chimney over the still hot intrusion. As pressures declined these conditions spread outward. Downward migration of the chimney occurred as the intrusion cooled and the brittle-ductile transition migrated to greater depths. Condensate that formed at the top of the vapor-dominated zone percolated downward and lowsalinity meteoric water entered the marginal parts of the system. Calcite, anhydrite, and fluorite precipitated in fractures upon heating. A progressive sealing of the fractures occurred, resulting in the downward migration of the cap rock. In response to

  18. Reservoir controling factors in the Karaha-Telaga Bodas