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• 1. [Image] Neutron Formation Temperature Gauge and Neutron Activation Analysis Brine Flow Meter. Final Report, October 1, 1976--March 31, 1978

  	Feasibility studies of nuclear techniques applicable to the determination of geothermal formation temperature and two-phase brine flow downhole have been performed. The formation temperature gauging technique ...
  	Citation × Citation Citation Abstract Copy Title: Neutron Formation Temperature Gauge and Neutron Activation Analysis Brine Flow Meter. Final Report, October 1, 1976--March 31, 1978 Author: Vagelatos, N. Year: 1978 Feasibility studies of nuclear techniques applicable to the determination of geothermal formation temperature and two-phase brine flow downhole have been performed. The formation temperature gauging technique involves injection of fast neutrons into the formation and analysis of the moderated slow neutron energy distribution by appropriately filtered neutron detectors. The scientific feasibility of the method has been demonstrated by analytical computational and experimental evaluation of the system response. A data analysis method has been developed to determine unambiguously the temperature, neutron absorption cross section and neutron moderating power of an arbitrary medium. The initial phase of a program to demonstrate the engineering feasibility of the technique has been performed. A sonde mockup was fabricated and measurements have been performed in a test stand designed to simulate a geothermal well. The results indicate that the formation temperature determined by this method is independent of differences between the temperature in the borehole fluid and the formation, borehole fluid density, and borehole fluid salinity. Estimates of performance specifications for a formation temperature sonde have been made on the basis of information obtained in this study and a conceptual design of a logging system has been developed. The technique for the determination of fluid flow in a well is based on neutron activation analysis of elements present in the brine. An analytical evaluation of the method has been performed. The results warrant further, experimental evaluation Title: Neutron Formation Temperature Gauge and Neutron Activation Analysis Brine Flow Meter. Final Report, October 1, 1976--March 31, 1978 Author: Vagelatos, N. Year: 1978 Feasibility studies of nuclear techniques applicable to the determination of geothermal formation temperature and two-phase brine flow downhole have been performed. The formation temperature gauging technique involves injection of fast neutrons into the formation and analysis of the moderated slow neutron energy distribution by appropriately filtered neutron detectors. The scientific feasibility of the method has been demonstrated by analytical computational and experimental evaluation of the system response. A data analysis method has been developed to determine unambiguously the temperature, neutron absorption cross section and neutron moderating power of an arbitrary medium. The initial phase of a program to demonstrate the engineering feasibility of the technique has been performed. A sonde mockup was fabricated and measurements have been performed in a test stand designed to simulate a geothermal well. The results indicate that the formation temperature determined by this method is independent of differences between the temperature in the borehole fluid and the formation, borehole fluid density, and borehole fluid salinity. Estimates of performance specifications for a formation temperature sonde have been made on the basis of information obtained in this study and a conceptual design of a logging system has been developed. The technique for the determination of fluid flow in a well is based on neutron activation analysis of elements present in the brine. An analytical evaluation of the method has been performed. The results warrant further, experimental evaluation Close

• 2. [Image] Geochemistry of the Colado geothermal area, Pershing County, Nevada

  	Multielement geochemical analysis of drill cuttings from 18 shallow and 2 intermediate-depth temperature gradient holes outlines an area of anomalous geochemistry related to the fluid flow and temperature ...
  	Citation × Citation Citation Abstract Copy Title: Geochemistry of the Colado geothermal area, Pershing County, Nevada Author: Christensen, O.D. Year: 1980 Multielement geochemical analysis of drill cuttings from 18 shallow and 2 intermediate-depth temperature gradient holes outlines an area of anomalous geochemistry related to the fluid flow and temperature distribution within the Colado geothermal area. The concentrations of Hg, As, Li, and Be belong to more than one statistical population and provide the clearest expression of hydrothermal processes. Enrichments of these four elements define anomalous zones which are spatially coincident with a measured temperature anomaly. The spatial distribution suggests that thermal fluid rises into alluvium in the vicinity of a major Basin and Range fault to depths of 200 to 400 feet (60 to 120 m), then flows laterally within shallow alluvial aquifers down the local hydrologic gradient. As the fluid cools, Li, Be, As, and Hg are deposited in response to changing physical and chemical conditions. As and Be appear to be deposited early in higher temperature zones; Li begins to deposit early but forms a rather dispersed geochemical anomaly; Hg is anomalous throughout the entire geothermal area but is concentrated in a shallow halo above the As and Be anomalies. The distributions suggest that the entry of thermal fluids from depth into the alluvium is spatially restricted to a small area and that the larger area of the observed thermal anomaly is due to the flow of warm fluid within shallow aquifers; DOE/ID/12079-9; ESL-39 Title: Geochemistry of the Colado geothermal area, Pershing County, Nevada Author: Christensen, O.D. Year: 1980 Multielement geochemical analysis of drill cuttings from 18 shallow and 2 intermediate-depth temperature gradient holes outlines an area of anomalous geochemistry related to the fluid flow and temperature distribution within the Colado geothermal area. The concentrations of Hg, As, Li, and Be belong to more than one statistical population and provide the clearest expression of hydrothermal processes. Enrichments of these four elements define anomalous zones which are spatially coincident with a measured temperature anomaly. The spatial distribution suggests that thermal fluid rises into alluvium in the vicinity of a major Basin and Range fault to depths of 200 to 400 feet (60 to 120 m), then flows laterally within shallow alluvial aquifers down the local hydrologic gradient. As the fluid cools, Li, Be, As, and Hg are deposited in response to changing physical and chemical conditions. As and Be appear to be deposited early in higher temperature zones; Li begins to deposit early but forms a rather dispersed geochemical anomaly; Hg is anomalous throughout the entire geothermal area but is concentrated in a shallow halo above the As and Be anomalies. The distributions suggest that the entry of thermal fluids from depth into the alluvium is spatially restricted to a small area and that the larger area of the observed thermal anomaly is due to the flow of warm fluid within shallow aquifers; DOE/ID/12079-9; ESL-39 Close

• 3. [Image] Evaluation and Design of Downhole Heat Exchangers for Direct Application; Annual Report, May 1, 1976 - July 1, 1977

  	Progress in an experimental and analytical research program to evaluate and improve the design of downhole heat exchangers (DHEs) for direct applications of geothermal energy is reported. Significant progress ...
  	Citation × Citation Citation Abstract Copy Title: Evaluation and Design of Downhole Heat Exchangers for Direct Application; Annual Report, May 1, 1976 - July 1, 1977 Author: Culver, G.G. Year: 1977 Progress in an experimental and analytical research program to evaluate and improve the design of downhole heat exchangers (DHEs) for direct applications of geothermal energy is reported. Significant progress has been achieved in characterizing flows in wells and without perforated casings and DHEs installed, determination of energy extraction rates for conventional DHEs in both cased and uncased wells, and utilization of information obtained to develop and substantiate models of heat transfer within the well. Flow characterization was obtained by experimentally measuring temperature and velocity profiles. In uncased wells, there was a relatively large vertical temperature gradient (approximately 0.5{sup 0}C/m) and insignificant measured vertical flow, while for the same wells when cased the temperature gradient was essentially zero (approximately 0.03{sup 0}C/m) and a large vertically upward flow was measured (9 to 14 cm/s as measured with a hot-film anemometer). These show that a significant connection cell is established after installation of the casing. The energy extraction rates for a conventional DHE both before and after casing of a 60 m deep well was experimentally measured. In the uncased well up to 300 kW was obtained while the cased well produced over 500 kW. Analytical heat transfer models were developed for the cased well both with and without DHEs. For the cased well without a DHE, the model predicts flow rates that agree with the measured value within about 30 percent. Further, the energy extraction rates predicted by the models agree even better with the measured values. These models allow the energy extraction rates of design parameter variations to be evaluated. At this stage, only trends can be shown but with additional substantiation they should produce optimum energy extraction designs Title: Evaluation and Design of Downhole Heat Exchangers for Direct Application; Annual Report, May 1, 1976 - July 1, 1977 Author: Culver, G.G. Year: 1977 Progress in an experimental and analytical research program to evaluate and improve the design of downhole heat exchangers (DHEs) for direct applications of geothermal energy is reported. Significant progress has been achieved in characterizing flows in wells and without perforated casings and DHEs installed, determination of energy extraction rates for conventional DHEs in both cased and uncased wells, and utilization of information obtained to develop and substantiate models of heat transfer within the well. Flow characterization was obtained by experimentally measuring temperature and velocity profiles. In uncased wells, there was a relatively large vertical temperature gradient (approximately 0.5{sup 0}C/m) and insignificant measured vertical flow, while for the same wells when cased the temperature gradient was essentially zero (approximately 0.03{sup 0}C/m) and a large vertically upward flow was measured (9 to 14 cm/s as measured with a hot-film anemometer). These show that a significant connection cell is established after installation of the casing. The energy extraction rates for a conventional DHE both before and after casing of a 60 m deep well was experimentally measured. In the uncased well up to 300 kW was obtained while the cased well produced over 500 kW. Analytical heat transfer models were developed for the cased well both with and without DHEs. For the cased well without a DHE, the model predicts flow rates that agree with the measured value within about 30 percent. Further, the energy extraction rates predicted by the models agree even better with the measured values. These models allow the energy extraction rates of design parameter variations to be evaluated. At this stage, only trends can be shown but with additional substantiation they should produce optimum energy extraction designs Close

• 4. [Image] An Experimental Investigation of the Permeability of Kayenta and St. Peter Sandstones to Hypersaline Brine in the Temperature Interval 70 to 90 C at 10. 3-MPa Confining Pressure

  	Permeabilities of 10.2 cm in length, 2.5 cm in diameter Kayenta (porosity, 20.7, +- 1.66%) and St. Peter (porosity, 13.6, +- 0.13%) sandstones to Magmamax No. 1 brine containing suspended solids were determined ...
  	Citation × Citation Citation Abstract Copy Title: An Experimental Investigation of the Permeability of Kayenta and St. Peter Sandstones to Hypersaline Brine in the Temperature Interval 70 to 90 C at 10. 3-MPa Confining Pressure Author: Piwinskii, A.J. Year: 1977 Permeabilities of 10.2 cm in length, 2.5 cm in diameter Kayenta (porosity, 20.7, +- 1.66%) and St. Peter (porosity, 13.6, +- 0.13%) sandstones to Magmamax No. 1 brine containing suspended solids were determined from 70 to 90/sup 0/C at 10.3-MPa confining pressure. Measurements were performed without filters, with one 10-..mu..m filter, and with two 10-..mu..m filters inserted upstream of the core sample. In all cases, there was a dramatic decrease in permeability within the first hour of flow or few hundred pore volumes of flow through the core. Experiments conducted without filters or with one filter yield permeabilities that represent both the rock and the 2- to 3-mm amorphous silica-iron layer on the top face of the core. The experimental results show that if the Salton Sea Geothermal Field (SSGF) were composed of porous, sedimentary formations similar to Kayenta sandstone, long-term injection of unmodified Magmamax brine would not be feasible. In the case of acidified brine, most of the permeability decline may result from the mobilization of calcite Title: An Experimental Investigation of the Permeability of Kayenta and St. Peter Sandstones to Hypersaline Brine in the Temperature Interval 70 to 90 C at 10. 3-MPa Confining Pressure Author: Piwinskii, A.J. Year: 1977 Permeabilities of 10.2 cm in length, 2.5 cm in diameter Kayenta (porosity, 20.7, +- 1.66%) and St. Peter (porosity, 13.6, +- 0.13%) sandstones to Magmamax No. 1 brine containing suspended solids were determined from 70 to 90/sup 0/C at 10.3-MPa confining pressure. Measurements were performed without filters, with one 10-..mu..m filter, and with two 10-..mu..m filters inserted upstream of the core sample. In all cases, there was a dramatic decrease in permeability within the first hour of flow or few hundred pore volumes of flow through the core. Experiments conducted without filters or with one filter yield permeabilities that represent both the rock and the 2- to 3-mm amorphous silica-iron layer on the top face of the core. The experimental results show that if the Salton Sea Geothermal Field (SSGF) were composed of porous, sedimentary formations similar to Kayenta sandstone, long-term injection of unmodified Magmamax brine would not be feasible. In the case of acidified brine, most of the permeability decline may result from the mobilization of calcite Close

• 5. [Image] Advanced Design and Economic Considerations for Commercial Geothermal Power Plants at Heber and Niland, California. Final Report

  	Two separate studies, involving advanced design and economic considerations for commercial geothermal power plants using liquid-dominated hydrothermal resources, are presented. In the first study, the ...
  	Citation × Citation Citation Abstract Copy Title: Advanced Design and Economic Considerations for Commercial Geothermal Power Plants at Heber and Niland, California. Final Report Author: Bechtel Corporation Year: 1977 Two separate studies, involving advanced design and economic considerations for commercial geothermal power plants using liquid-dominated hydrothermal resources, are presented. In the first study, the effects on design, capital cost, and bus bar electric energy production cost caused by an anticipated decline in available geothermal fluid temperature over the lifetime of power plants are described. A two-stage, flashed-steam energy conversion process was used for the conceptual design of the power plants, which operate from the moderate-temperature, low-salinity reservoir at Heber, California. Plants with net capacities of 50, 100, and 200 MWe (net) were investigated. The results show that it is important to include provision for geothermal fluid temperature decline in the design of power plants to prevent loss of electric energy production capability and to reduce bus bar electric energy costs. In the second study, the technical, economic, and environmental effects of adding regeneration to a 50 MWe (net) power plant employing the multistage-flash/binary process are described. Regeneration is potentially attractive because it recovers waste heat from the turbine exhaust and uses it in the power cycle. However, the pressure drop caused by the introduction of the regenerator decreases the turbine expansion and thus decreases system performance. An innovative approach was taken in the design of the regenerator, which minimized the expected performance degradation of the turbine. The result was that the performance, capital cost, and bus bar electric energy production cost are nearly the same for the processes with and without regeneration. On the other hand, the addition of regeneration has the environmental benefits of substantially reducing heat rejection to the atmosphere and cooling tower makeup and blowdown water requirements. It also increases the temperature of the brine returned to the field for reinjection Title: Advanced Design and Economic Considerations for Commercial Geothermal Power Plants at Heber and Niland, California. Final Report Author: Bechtel Corporation Year: 1977 Two separate studies, involving advanced design and economic considerations for commercial geothermal power plants using liquid-dominated hydrothermal resources, are presented. In the first study, the effects on design, capital cost, and bus bar electric energy production cost caused by an anticipated decline in available geothermal fluid temperature over the lifetime of power plants are described. A two-stage, flashed-steam energy conversion process was used for the conceptual design of the power plants, which operate from the moderate-temperature, low-salinity reservoir at Heber, California. Plants with net capacities of 50, 100, and 200 MWe (net) were investigated. The results show that it is important to include provision for geothermal fluid temperature decline in the design of power plants to prevent loss of electric energy production capability and to reduce bus bar electric energy costs. In the second study, the technical, economic, and environmental effects of adding regeneration to a 50 MWe (net) power plant employing the multistage-flash/binary process are described. Regeneration is potentially attractive because it recovers waste heat from the turbine exhaust and uses it in the power cycle. However, the pressure drop caused by the introduction of the regenerator decreases the turbine expansion and thus decreases system performance. An innovative approach was taken in the design of the regenerator, which minimized the expected performance degradation of the turbine. The result was that the performance, capital cost, and bus bar electric energy production cost are nearly the same for the processes with and without regeneration. On the other hand, the addition of regeneration has the environmental benefits of substantially reducing heat rejection to the atmosphere and cooling tower makeup and blowdown water requirements. It also increases the temperature of the brine returned to the field for reinjection Close

• 6. [Image] Testing Operations Plan: Coso Geothermal Exploratory Hole No. 1 (CGEH-1)

  	Coso Geothermal Exploratory Hole No. 1 (CGEH-1) was drilled to investigate the potential of the Coso Hot Springs Known Geothermal Resource Area (KGRA) in southeastern California. Detailed background information ...
  	Citation × Citation Citation Abstract Copy Title: Testing Operations Plan: Coso Geothermal Exploratory Hole No. 1 (CGEH-1) Author: Nevada Operations Office; Naval Weapons Center, China Lake Year: 1978 Coso Geothermal Exploratory Hole No. 1 (CGEH-1) was drilled to investigate the potential of the Coso Hot Springs Known Geothermal Resource Area (KGRA) in southeastern California. Detailed background information is contained in the drilling plan, ''Coso Geothermal Exploratory Hole No. 1 (CGEH-1),'' NVO-184, dated June 1977. The purpose of this supplement to NVO-184 is to establish a plan of operations for testing the resource after completion of well drilling activities. Major elements of this plan include setting forth the management and organizational concept to be followed, describing the generalized site activities required and the well testing operations, and establishing schedules, environmental considerations, and technical documentation requirements. The objective of this testing is to determine the well productivity and geothermal reservoir parameters. The testing will consist of both static and dynamic measurements. The static measurements will include wellhead pressure monitoring plus downhole temperature and pressure surveys conducted with the well shut in. The dynamic measurements will include downhole and surface pressure, temperature, and flow rate data with the well producing at varying rates. Two types of dynamic tests are contemplated; the first utilizing the James Method and the second utilizing a separator test system, if justified by an evaluation of the resource potential Title: Testing Operations Plan: Coso Geothermal Exploratory Hole No. 1 (CGEH-1) Author: Nevada Operations Office; Naval Weapons Center, China Lake Year: 1978 Coso Geothermal Exploratory Hole No. 1 (CGEH-1) was drilled to investigate the potential of the Coso Hot Springs Known Geothermal Resource Area (KGRA) in southeastern California. Detailed background information is contained in the drilling plan, ''Coso Geothermal Exploratory Hole No. 1 (CGEH-1),'' NVO-184, dated June 1977. The purpose of this supplement to NVO-184 is to establish a plan of operations for testing the resource after completion of well drilling activities. Major elements of this plan include setting forth the management and organizational concept to be followed, describing the generalized site activities required and the well testing operations, and establishing schedules, environmental considerations, and technical documentation requirements. The objective of this testing is to determine the well productivity and geothermal reservoir parameters. The testing will consist of both static and dynamic measurements. The static measurements will include wellhead pressure monitoring plus downhole temperature and pressure surveys conducted with the well shut in. The dynamic measurements will include downhole and surface pressure, temperature, and flow rate data with the well producing at varying rates. Two types of dynamic tests are contemplated; the first utilizing the James Method and the second utilizing a separator test system, if justified by an evaluation of the resource potential Close

• 7. [Image] Electricity from Hot Dry Rock Geothermal Energy: Technical and Economic Issues

  	Extraction of energy from hot dry rock would make available a nearly unlimited energy source. Some of the technical problems and possible economic tradeoffs involved in a power generating system are examined ...
  	Citation × Citation Citation Abstract Copy Title: Electricity from Hot Dry Rock Geothermal Energy: Technical and Economic Issues Author: Tester, J.W. Year: 1979 Extraction of energy from hot dry rock would make available a nearly unlimited energy source. Some of the technical problems and possible economic tradeoffs involved in a power generating system are examined and possible solutions proposed. An intertemporal optimization computer model of electricity production from a hot dry rock geothermal source has been constructed. The effects of reservoir degradation, variable fluid flow rate, and drilling operations are examined to determine optimal strategies for reservoir management and necessary conditions for economic feasibility Title: Electricity from Hot Dry Rock Geothermal Energy: Technical and Economic Issues Author: Tester, J.W. Year: 1979 Extraction of energy from hot dry rock would make available a nearly unlimited energy source. Some of the technical problems and possible economic tradeoffs involved in a power generating system are examined and possible solutions proposed. An intertemporal optimization computer model of electricity production from a hot dry rock geothermal source has been constructed. The effects of reservoir degradation, variable fluid flow rate, and drilling operations are examined to determine optimal strategies for reservoir management and necessary conditions for economic feasibility Close

• 8. [Image] Subsurface investigations at the Roosevelt KGRA, Utah. Final report

  	An investigation of the geothermal reservoir in the Roosevelt Hot Springs Known Geothermal Resource Area in Utah was carried out. The objective of this effort was to develop predictions for well production ...
  	Citation × Citation Citation Abstract Copy Title: Subsurface investigations at the Roosevelt KGRA, Utah. Final report Author: Butz, J. Year: 1979 An investigation of the geothermal reservoir in the Roosevelt Hot Springs Known Geothermal Resource Area in Utah was carried out. The objective of this effort was to develop predictions for well production capacities, based on data taken during field tests and through use of a computer model. In turn, the production information could then be used in design optimization and economic analyses for development of the resource under study. Flow tests of a geothermal well, Utah State 14-2, were conducted. Data consisting of pressure and temperature logs as a function of depth were obtained. Maximum recorded temperature was 503/sup 0/F (262/sup 0/C) and maximum pressure, 954 psia (6.58MPa) as measured under flow conditions. Tests were run at rates up to 580,000 lb/hr (73.3 kg/sec) total flow. The information gathered during the testing was reduced and compared to results of a predictive computer model. Reservoir conditions in the Roosevelt Hot Springs KGRA are such that two-phase flow exists in the wellbore and, in some cases, also in the reservoir itself. The computer model employed in the analysis reflects current efforts to improve the state-of-the-art in the prediction of two-phase pressure drops in vertical systems. Predictions at flowrates of up to 300,000 lb/hr (38 kg/sec) matched quite well with test data, while modeling at higher flowrates (to maximum tested) showed progressively greater deviation from test data. Cause of the observed degradation is postulated to be the movement of the flash horizon into the reservoir, due to drawdown at high flowrates; DOE/ET/28389-1 Title: Subsurface investigations at the Roosevelt KGRA, Utah. Final report Author: Butz, J. Year: 1979 An investigation of the geothermal reservoir in the Roosevelt Hot Springs Known Geothermal Resource Area in Utah was carried out. The objective of this effort was to develop predictions for well production capacities, based on data taken during field tests and through use of a computer model. In turn, the production information could then be used in design optimization and economic analyses for development of the resource under study. Flow tests of a geothermal well, Utah State 14-2, were conducted. Data consisting of pressure and temperature logs as a function of depth were obtained. Maximum recorded temperature was 503/sup 0/F (262/sup 0/C) and maximum pressure, 954 psia (6.58MPa) as measured under flow conditions. Tests were run at rates up to 580,000 lb/hr (73.3 kg/sec) total flow. The information gathered during the testing was reduced and compared to results of a predictive computer model. Reservoir conditions in the Roosevelt Hot Springs KGRA are such that two-phase flow exists in the wellbore and, in some cases, also in the reservoir itself. The computer model employed in the analysis reflects current efforts to improve the state-of-the-art in the prediction of two-phase pressure drops in vertical systems. Predictions at flowrates of up to 300,000 lb/hr (38 kg/sec) matched quite well with test data, while modeling at higher flowrates (to maximum tested) showed progressively greater deviation from test data. Cause of the observed degradation is postulated to be the movement of the flash horizon into the reservoir, due to drawdown at high flowrates; DOE/ET/28389-1 Close

• 9. [Image] Transient well testing in two-phase geothermal reservoirs

  	A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto ...
  	Citation × Citation Citation Abstract Copy Title: Transient well testing in two-phase geothermal reservoirs Author: Aydelotte, S.R. Year: 1980 A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto and the Hawaiian Geothermal project have been history matched. Using these well tests as a base, the influence of reservoir permeability, porosity, thickness, and heat capacity, along with flow rate and fracturing were studied. Single and two-phase transient well test equations were used to analyze these tests with poor results due to rapidly changing fluid properties and inability to calculate the flowing steam saturation in the reservoir. The injection of cold water into the reservoir does give good data from which formation properties can be calculated. Title: Transient well testing in two-phase geothermal reservoirs Author: Aydelotte, S.R. Year: 1980 A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto and the Hawaiian Geothermal project have been history matched. Using these well tests as a base, the influence of reservoir permeability, porosity, thickness, and heat capacity, along with flow rate and fracturing were studied. Single and two-phase transient well test equations were used to analyze these tests with poor results due to rapidly changing fluid properties and inability to calculate the flowing steam saturation in the reservoir. The injection of cold water into the reservoir does give good data from which formation properties can be calculated. Close