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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] Drilling fluid/formation interaction at simulated in situ geothermal conditions. Final report

  	Interaction of drilling fluids with a geothermal reservoir formation can result in significant permeability impairment and therefore reduced well productivity. This interaction is studied under simulated ...
  	Citation × Citation Citation Abstract Copy Title: Drilling fluid/formation interaction at simulated in situ geothermal conditions. Final report Author: Enniss, D.O Year: 1980 Interaction of drilling fluids with a geothermal reservoir formation can result in significant permeability impairment and therefore reduced well productivity. This interaction is studied under simulated in situ geothermal conditions of overburden stress, pore fluid pressure, temperature, and pore fluid chemistry. Permeability impairment of an East Mesa KGRA reservoir material is evaluated as a function of stagnation time, drilling fluid, and temperature. Results indicate that all of these parameters contribute significantly to the magnitude and the reversibility of the impairment. Title: Drilling fluid/formation interaction at simulated in situ geothermal conditions. Final report Author: Enniss, D.O Year: 1980 Interaction of drilling fluids with a geothermal reservoir formation can result in significant permeability impairment and therefore reduced well productivity. This interaction is studied under simulated in situ geothermal conditions of overburden stress, pore fluid pressure, temperature, and pore fluid chemistry. Permeability impairment of an East Mesa KGRA reservoir material is evaluated as a function of stagnation time, drilling fluid, and temperature. Results indicate that all of these parameters contribute significantly to the magnitude and the reversibility of the impairment. 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] Field Electrochemical Measurements of Corrosion Characteristics of Materials in Hypersaline Geothermal Brine

  	A flow cell (with appropriate accessories) was developed for use in short-term testing of the corrosion behavior of materials in approximately 100{sup 0}C, hypersaline geothermal brine. The apparatus was ...
  	Citation × Citation Citation Abstract Copy Title: Field Electrochemical Measurements of Corrosion Characteristics of Materials in Hypersaline Geothermal Brine Author: Harrar, J.E. Year: 1977 A flow cell (with appropriate accessories) was developed for use in short-term testing of the corrosion behavior of materials in approximately 100{sup 0}C, hypersaline geothermal brine. The apparatus was designed to accommodate commercial (Petrolite) corrosion measurement equipment and conducted experiments on-line at the Lawrence Livermore Laboratory Test Station in the Salton Sea Geothermal Field. The apparatus also permitted direct readings of corrosion potentials, solution redox potential (E{sub h}), brine flow rate, pH, and temperature. Estimates of general corrosion rates were obtained by the linear polarization resistance technique and from measurements of complete potentiodynamic polarization curves. The latter also afforded predictions of pitting susceptibilities of active-passive type materials. Twenty-two alloys (with various heat treatments) were tested and readily grouped according to general corrosion resistances in acidified hypersaline (approximately 4 M chloride) brine. Especially promising in regard to corrosion resistance-vs-cost is the series of low Cr--Mo steels. Prescaling of materials in unacidified (pH approximately 5.7) brine prior to exposure to acidified (pH 2 to 4.5) brine was found to be beneficial in reducing corrosion rates at 100{sup 0}C Title: Field Electrochemical Measurements of Corrosion Characteristics of Materials in Hypersaline Geothermal Brine Author: Harrar, J.E. Year: 1977 A flow cell (with appropriate accessories) was developed for use in short-term testing of the corrosion behavior of materials in approximately 100{sup 0}C, hypersaline geothermal brine. The apparatus was designed to accommodate commercial (Petrolite) corrosion measurement equipment and conducted experiments on-line at the Lawrence Livermore Laboratory Test Station in the Salton Sea Geothermal Field. The apparatus also permitted direct readings of corrosion potentials, solution redox potential (E{sub h}), brine flow rate, pH, and temperature. Estimates of general corrosion rates were obtained by the linear polarization resistance technique and from measurements of complete potentiodynamic polarization curves. The latter also afforded predictions of pitting susceptibilities of active-passive type materials. Twenty-two alloys (with various heat treatments) were tested and readily grouped according to general corrosion resistances in acidified hypersaline (approximately 4 M chloride) brine. Especially promising in regard to corrosion resistance-vs-cost is the series of low Cr--Mo steels. Prescaling of materials in unacidified (pH approximately 5.7) brine prior to exposure to acidified (pH 2 to 4.5) brine was found to be beneficial in reducing corrosion rates at 100{sup 0}C Close

• 5. [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

• 6. [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

• 7. [Image] Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California

  	The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California Author: Howard, J. Year: 1978 The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production tests in the northern portion of the East Mesa KGRA, conversion tables, chemical analysis of fluids from East Mesa wells, and results of laboratory studies of scale samples taken from the vertical tube evaporator. (MHR) Title: Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California Author: Howard, J. Year: 1978 The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production tests in the northern portion of the East Mesa KGRA, conversion tables, chemical analysis of fluids from East Mesa wells, and results of laboratory studies of scale samples taken from the vertical tube evaporator. (MHR) Close

• 8. [Image] Geopressured Energy Resource Evaluation

  	The geopressured aquifers that extend along the northern Gulf of Mexico are a large, perhaps the largest, potential source of geothermal energy and natural gas in the US. Because of the high cost of completing ...
  	Citation × Citation Citation Abstract Copy Title: Geopressured Energy Resource Evaluation Author: Samuels, G. Year: 1979 The geopressured aquifers that extend along the northern Gulf of Mexico are a large, perhaps the largest, potential source of geothermal energy and natural gas in the US. Because of the high cost of completing wells into these formations and their relatively low temperatures (200 to 400 F), the utilization of the geothermal energy will be highly depend on, and of secondary importance to, the value of the methane. The economics of extracting either the geothermal energy or natural gas from these aquifers does not look promising. The combined requirements of high well flow rates (40,000 bbl/day), long life (20 years), and the necessity for close well spacing to minimize the cost of the collection system may be incompatible with the actual characteristics of the reservoirs. These factors place such stringent requirements on the reservoir size, permeability, and compressibility, or specific storage coefficient, that the number of promising production areas may be severely limited Title: Geopressured Energy Resource Evaluation Author: Samuels, G. Year: 1979 The geopressured aquifers that extend along the northern Gulf of Mexico are a large, perhaps the largest, potential source of geothermal energy and natural gas in the US. Because of the high cost of completing wells into these formations and their relatively low temperatures (200 to 400 F), the utilization of the geothermal energy will be highly depend on, and of secondary importance to, the value of the methane. The economics of extracting either the geothermal energy or natural gas from these aquifers does not look promising. The combined requirements of high well flow rates (40,000 bbl/day), long life (20 years), and the necessity for close well spacing to minimize the cost of the collection system may be incompatible with the actual characteristics of the reservoirs. These factors place such stringent requirements on the reservoir size, permeability, and compressibility, or specific storage coefficient, that the number of promising production areas may be severely limited 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