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• 1. [Image] Geothermal Heating System for the Children's Museum of Utah

  	The results of a study to determine the engineering and economic feasibility of using the Wasatch Hot Spring resource for space heating of the Children's Library building are presented. The Wasatch Hot ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Heating System for the Children's Museum of Utah Author: Karlsson, T. Year: 1984 The results of a study to determine the engineering and economic feasibility of using the Wasatch Hot Spring resource for space heating of the Children's Library building are presented. The Wasatch Hot Spring with a reported flow of about 63 gpm (240 l/min) at an average temperature of 104/sup 0/F is not capable of furnishing the needed heat for the Children's Museum building. The underground paths along which the thermal waters flow to their outlets at the Warm Springs Fault are not presently known. It is possible if the thermal water ascends from the deep layers of the earth along the Warm Springs Fault that increased geothermal flow at a higher temperature can be produced by drilling into the fault. Assuming that sufficient geothermal fluid quantity is produced by drilling in the area, an analysis is made of a geothermal heating system for the building based on different fluid temperatures. It is assumed that the present and planned heating systems be left intact with the gas fired boilers taking over during cold periods when the geothermal system fails to provide sufficient heat. Economic analysis shows that the geothermal system is very attractive, even for the lowest geothermal fluid temperature considered (110/sup 0/F) Title: Geothermal Heating System for the Children's Museum of Utah Author: Karlsson, T. Year: 1984 The results of a study to determine the engineering and economic feasibility of using the Wasatch Hot Spring resource for space heating of the Children's Library building are presented. The Wasatch Hot Spring with a reported flow of about 63 gpm (240 l/min) at an average temperature of 104/sup 0/F is not capable of furnishing the needed heat for the Children's Museum building. The underground paths along which the thermal waters flow to their outlets at the Warm Springs Fault are not presently known. It is possible if the thermal water ascends from the deep layers of the earth along the Warm Springs Fault that increased geothermal flow at a higher temperature can be produced by drilling into the fault. Assuming that sufficient geothermal fluid quantity is produced by drilling in the area, an analysis is made of a geothermal heating system for the building based on different fluid temperatures. It is assumed that the present and planned heating systems be left intact with the gas fired boilers taking over during cold periods when the geothermal system fails to provide sufficient heat. Economic analysis shows that the geothermal system is very attractive, even for the lowest geothermal fluid temperature considered (110/sup 0/F) Close

• 2. [Image] Klamath Falls Geothermal Heating System: Data from Four Months of Testing

  	This data report includes graphs of water levels measured in 16 wells, temperature measurement in 8 wells, 14 system operation points taken on a 2, 4, and 8 hour time schedule, BTU usage as measured to ...
  	Citation × Citation Citation Abstract Copy Title: Klamath Falls Geothermal Heating System: Data from Four Months of Testing Author: Gerety, T. Year: 1984 This data report includes graphs of water levels measured in 16 wells, temperature measurement in 8 wells, 14 system operation points taken on a 2, 4, and 8 hour time schedule, BTU usage as measured to each building, BTU estimates from operation data, daily air temperatures, storm sewer discharge flow, historical well development and other collected information Title: Klamath Falls Geothermal Heating System: Data from Four Months of Testing Author: Gerety, T. Year: 1984 This data report includes graphs of water levels measured in 16 wells, temperature measurement in 8 wells, 14 system operation points taken on a 2, 4, and 8 hour time schedule, BTU usage as measured to each building, BTU estimates from operation data, daily air temperatures, storm sewer discharge flow, historical well development and other collected information Close

• 3. [Image] Test Drilling at Soldier Creek, Rosebud Indian Reservation, Todd County, South Dakota

  	Thirty-six test holes were augered by the U.S. Geological Survey in the vicinity of Soldier Creek, Rosebud Indian Reservation, Todd County, South Dakota. Wells producing more than 5 gallons per minute ...
  	Citation × Citation Citation Abstract Copy Title: Test Drilling at Soldier Creek, Rosebud Indian Reservation, Todd County, South Dakota Author: Adolphson, D. G. Year: 1975 Thirty-six test holes were augered by the U.S. Geological Survey in the vicinity of Soldier Creek, Rosebud Indian Reservation, Todd County, South Dakota. Wells producing more than 5 gallons per minute (0.32 liter per second) from the Tertiary deposits are rare. However, as much as 20 feet (6.1 meters) of permeable alluvial deposits were penetrated in several test holes. One test well was pumped for 2 hours at a rate of 10 gallons per minute (0.63 liter per second) Title: Test Drilling at Soldier Creek, Rosebud Indian Reservation, Todd County, South Dakota Author: Adolphson, D. G. Year: 1975 Thirty-six test holes were augered by the U.S. Geological Survey in the vicinity of Soldier Creek, Rosebud Indian Reservation, Todd County, South Dakota. Wells producing more than 5 gallons per minute (0.32 liter per second) from the Tertiary deposits are rare. However, as much as 20 feet (6.1 meters) of permeable alluvial deposits were penetrated in several test holes. One test well was pumped for 2 hours at a rate of 10 gallons per minute (0.63 liter per second) Close

• 4. [Image] Pressure transient testing of a manmade fractured geothermal reservoir: an examination of fracture versus matrix dominated flow effects

  	The data analysis is in terms of a diffusion equation that determines the flow of water and hence the pressure in the main fracture system, associated joints, and the matrix permeability. The fits of the ...
  	Citation × Citation Citation Abstract Copy Title: Pressure transient testing of a manmade fractured geothermal reservoir: an examination of fracture versus matrix dominated flow effects Author: Fisher, H.N. Year: 1980 The data analysis is in terms of a diffusion equation that determines the flow of water and hence the pressure in the main fracture system, associated joints, and the matrix permeability. The fits of the flow data to type curve solutions of the diffusion equation with pressure-dependent properties for various flow geometries are presented. The following points are considered in detail. (1) The limits on the fracture geometry, aperture, and diffusing areas are determined from the diffusion parameters. (2) Dependence of the parameters (impedance, diffusivity) of the flow-through systems are related to the inflation of the major fractures. (3) The rock properties are related to the reservoir compressibility and permeability. In particular, laboratory experiments have shown that the properties of all sizes of cracks from large single fractures to the microstructure are pressure dependent if the fluid pressure is near the confining stress. The effects of this pressure dependence on the form of the type curves are included. (4) The competition of flow into the various types of porosity (main fractures, joints, and microstructure) and the effect on the interpretation of type curves are considered. The approach described makes an important departure from conventional pressure-transient reservoir analysis in that pressure-dependent properties are incorporated into a numerically simulated generation of type curves resulting from one- and two-dimensional diffusion. In addition, the problem of specifying a unique flow geometry where both matrix and fracture-dominated, non-Darcy flow effects are possible is analyzed using a large amount of field and laboratory data in conjunction with a theoretical treatment that reviews the existing state of the art in reservoir mechanics.; LA-8535-MS Title: Pressure transient testing of a manmade fractured geothermal reservoir: an examination of fracture versus matrix dominated flow effects Author: Fisher, H.N. Year: 1980 The data analysis is in terms of a diffusion equation that determines the flow of water and hence the pressure in the main fracture system, associated joints, and the matrix permeability. The fits of the flow data to type curve solutions of the diffusion equation with pressure-dependent properties for various flow geometries are presented. The following points are considered in detail. (1) The limits on the fracture geometry, aperture, and diffusing areas are determined from the diffusion parameters. (2) Dependence of the parameters (impedance, diffusivity) of the flow-through systems are related to the inflation of the major fractures. (3) The rock properties are related to the reservoir compressibility and permeability. In particular, laboratory experiments have shown that the properties of all sizes of cracks from large single fractures to the microstructure are pressure dependent if the fluid pressure is near the confining stress. The effects of this pressure dependence on the form of the type curves are included. (4) The competition of flow into the various types of porosity (main fractures, joints, and microstructure) and the effect on the interpretation of type curves are considered. The approach described makes an important departure from conventional pressure-transient reservoir analysis in that pressure-dependent properties are incorporated into a numerically simulated generation of type curves resulting from one- and two-dimensional diffusion. In addition, the problem of specifying a unique flow geometry where both matrix and fracture-dominated, non-Darcy flow effects are possible is analyzed using a large amount of field and laboratory data in conjunction with a theoretical treatment that reviews the existing state of the art in reservoir mechanics.; LA-8535-MS Close

• 5. [Image] Feasibility of a Geothermal Heating System for Oakridge, Oregon

  	Geological and geophysical data indicate that Oakridge is underlain by geothermal waters. The strongest evidence is from the geothermal gradient, the increase of temperature with depth, in a 400' well ...
  	Citation × Citation Citation Abstract Copy Title: Feasibility of a Geothermal Heating System for Oakridge, Oregon Author: Bowen, R.C. Year: 1979 Geological and geophysical data indicate that Oakridge is underlain by geothermal waters. The strongest evidence is from the geothermal gradient, the increase of temperature with depth, in a 400' well on the south edge of the City. Although this well shows signs of disturbance by ground water, the geothermal gradient appears to be similar to the gradient from a well near McCredie Hot Springs seven miles to the east. Additional evidence is a salt spring, just south of the City, that may represent a fossil geothermal system that has become sealed and is no longer flowing hot water. A third line of direct evidence is the presence of a warm spring about three miles southeast of the City that is now covered by Hills Creek Reservoir. Indirect geophysical evidence is a high gravity gradient from west to east near Oakridge. This gradient relates closely to the region of increasing geothermal gradient and heat flow of the Cascade Geothermal Anomaly. Indications of intersection of regional fault patterns could provide the subsurface fracturing and permeability necessary for a geothermal reservoir. The results of this study indicate that water sufficiently hot to be useful can be located by drilling to depths of three to four thousand feet at Oakridge. Three sites are proposed for shallow geothermal gradient holes to test the proposed model. Title: Feasibility of a Geothermal Heating System for Oakridge, Oregon Author: Bowen, R.C. Year: 1979 Geological and geophysical data indicate that Oakridge is underlain by geothermal waters. The strongest evidence is from the geothermal gradient, the increase of temperature with depth, in a 400' well on the south edge of the City. Although this well shows signs of disturbance by ground water, the geothermal gradient appears to be similar to the gradient from a well near McCredie Hot Springs seven miles to the east. Additional evidence is a salt spring, just south of the City, that may represent a fossil geothermal system that has become sealed and is no longer flowing hot water. A third line of direct evidence is the presence of a warm spring about three miles southeast of the City that is now covered by Hills Creek Reservoir. Indirect geophysical evidence is a high gravity gradient from west to east near Oakridge. This gradient relates closely to the region of increasing geothermal gradient and heat flow of the Cascade Geothermal Anomaly. Indications of intersection of regional fault patterns could provide the subsurface fracturing and permeability necessary for a geothermal reservoir. The results of this study indicate that water sufficiently hot to be useful can be located by drilling to depths of three to four thousand feet at Oakridge. Three sites are proposed for shallow geothermal gradient holes to test the proposed model. Close

• 6. [Image] Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

  	The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and ...
  	Citation × Citation Citation Abstract Copy Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustics logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustics logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Close

• 7. [Image] Geothermal Investigations in Idaho. Part 8. Heat Flow Study of the Snake River Plain Region, Idaho

  	The Snake River Plain of Idaho has recent lava flows and a large number of thermal springs and wells. A heat flow study was initiated which, together with available geological and geophysical information, ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Investigations in Idaho. Part 8. Heat Flow Study of the Snake River Plain Region, Idaho Author: Brott, C.A. Year: 1976 The Snake River Plain of Idaho has recent lava flows and a large number of thermal springs and wells. A heat flow study was initiated which, together with available geological and geophysical information, allows a better definition of the geothermal resource and evaluation of the geothermal potential. Local geothermal anomalies were not the objects of this study and have not been studied in detail. The quality of the heat flow values obtained varies as interpretation was necessary to determine geothermal gradients for many of the holes which had disturbances. A major problem in determining the heat flow values is the lack of knowledge of the in situ porosity of the rocks. The heat flow values obtained for the Eastern Snake River Plain are from shallow wells (< 200 m), hence the heat flow there is low (< 0.5 HFU) because of the water movement in the Snake Plain aquifer. The anomalous regional heat flow pattern around the Snake River Plain, together with other geophysical and geological data, suggest the presence of a major crustal heat source. With the exception of the area of the Snake Plain aquifer, high geothermal gradients were found in all areas of southern Idaho (40 to 100/sup 0/C/km). Temperatures hot enough for space heating can be found most anywhere in the Plain at relatively shallow depths (1 to 2 km). Temperatures hot enough for electrical power generation (200/sup 0/C) can be found beneath southern Idaho almost anywhere at depths of 3 to 4 kilometers. The Plain is fault bounded and hot water circulating along the fault zones from depths can be a very important geothermal resource at shallow depths. The margins of the Plain have the highest heat flow values, are the most faulted, and have possibly the highest geothermal resource potential Title: Geothermal Investigations in Idaho. Part 8. Heat Flow Study of the Snake River Plain Region, Idaho Author: Brott, C.A. Year: 1976 The Snake River Plain of Idaho has recent lava flows and a large number of thermal springs and wells. A heat flow study was initiated which, together with available geological and geophysical information, allows a better definition of the geothermal resource and evaluation of the geothermal potential. Local geothermal anomalies were not the objects of this study and have not been studied in detail. The quality of the heat flow values obtained varies as interpretation was necessary to determine geothermal gradients for many of the holes which had disturbances. A major problem in determining the heat flow values is the lack of knowledge of the in situ porosity of the rocks. The heat flow values obtained for the Eastern Snake River Plain are from shallow wells (< 200 m), hence the heat flow there is low (< 0.5 HFU) because of the water movement in the Snake Plain aquifer. The anomalous regional heat flow pattern around the Snake River Plain, together with other geophysical and geological data, suggest the presence of a major crustal heat source. With the exception of the area of the Snake Plain aquifer, high geothermal gradients were found in all areas of southern Idaho (40 to 100/sup 0/C/km). Temperatures hot enough for space heating can be found most anywhere in the Plain at relatively shallow depths (1 to 2 km). Temperatures hot enough for electrical power generation (200/sup 0/C) can be found beneath southern Idaho almost anywhere at depths of 3 to 4 kilometers. The Plain is fault bounded and hot water circulating along the fault zones from depths can be a very important geothermal resource at shallow depths. The margins of the Plain have the highest heat flow values, are the most faulted, and have possibly the highest geothermal resource potential Close

• 8. [Image] Thermal Fracture Effects in Geothermal Energy Extraction

  	Heat and water exchange between the primary crack and a lateral thermal fracture are analyzed by means of numerical modeling on a high-speed computer. Three-dimensional heat flow in the rock is coupled ...
  	Citation × Citation Citation Abstract Copy Title: Thermal Fracture Effects in Geothermal Energy Extraction Author: Demuth, R.B. Year: 1979 Heat and water exchange between the primary crack and a lateral thermal fracture are analyzed by means of numerical modeling on a high-speed computer. Three-dimensional heat flow in the rock is coupled to a two-dimensional approximation for the time-varying convective patterns that result from both forced flow and buoyancy. The physical and mathematical bases for the study are described together with the numerical technique for solution. The report includes listing of three versions of the computer code and some results of representative calculations Title: Thermal Fracture Effects in Geothermal Energy Extraction Author: Demuth, R.B. Year: 1979 Heat and water exchange between the primary crack and a lateral thermal fracture are analyzed by means of numerical modeling on a high-speed computer. Three-dimensional heat flow in the rock is coupled to a two-dimensional approximation for the time-varying convective patterns that result from both forced flow and buoyancy. The physical and mathematical bases for the study are described together with the numerical technique for solution. The report includes listing of three versions of the computer code and some results of representative calculations Close

• 9. [Image] Hot Dry Rock Geothermal Energy Development Program: Annual Report, Fiscal Year 1987

  	During fiscal year 1987, emphasis in the Hot Dry Rock Geothermal Energy Development Program was on preparations for a " Long-Term Flow Test " of the "Phase II" or "Engineering" hot dry rock energy system ...
  	Citation × Citation Citation Abstract Copy Title: Hot Dry Rock Geothermal Energy Development Program: Annual Report, Fiscal Year 1987 Author: Smith, M.C. Year: 1989 During fiscal year 1987, emphasis in the Hot Dry Rock Geothermal Energy Development Program was on preparations for a " Long-Term Flow Test " of the "Phase II" or "Engineering" hot dry rock energy system at Fenton Hill, New Mexico. A successful 30 day flow test of the system during FY86 indicated that such a system would produce heat at at temperature and rate that could support operation of a commercial electrical power plant. However, it did not answer certain questions basic to the economics of long-term operation, including the rate of depletion of the thermal reservoir, the rate of water loss from the system, and the possibility of operating problems during extended continuous operation. Preparations for a one year flow test of the system to answer these and more fundamental questions concerning hot dry rock systems were made in FY87: design of the required surface facilities; procurement and installation of some of their components; development and testing of slim line logging tools for use through small-diameter production tubing; research on temperature-sensitive reactive chemical tracers to monitor thermal depletion of the reservoir; and computer simulations of the 30-day test, extended to modeling the planned Long-Term Flow Test Title: Hot Dry Rock Geothermal Energy Development Program: Annual Report, Fiscal Year 1987 Author: Smith, M.C. Year: 1989 During fiscal year 1987, emphasis in the Hot Dry Rock Geothermal Energy Development Program was on preparations for a " Long-Term Flow Test " of the "Phase II" or "Engineering" hot dry rock energy system at Fenton Hill, New Mexico. A successful 30 day flow test of the system during FY86 indicated that such a system would produce heat at at temperature and rate that could support operation of a commercial electrical power plant. However, it did not answer certain questions basic to the economics of long-term operation, including the rate of depletion of the thermal reservoir, the rate of water loss from the system, and the possibility of operating problems during extended continuous operation. Preparations for a one year flow test of the system to answer these and more fundamental questions concerning hot dry rock systems were made in FY87: design of the required surface facilities; procurement and installation of some of their components; development and testing of slim line logging tools for use through small-diameter production tubing; research on temperature-sensitive reactive chemical tracers to monitor thermal depletion of the reservoir; and computer simulations of the 30-day test, extended to modeling the planned Long-Term Flow Test Close

• 10. [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