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Development of hot dry rock geothermal resources; technical and economic issues

Description: Technical and economic issues related to the commercial feasibility of hot dry rock geothermal energy for producing electricity and heat are discussed. Topics covered include resource characteristics, reservoir thermal capacity and lifetime, drilling and surface plant costs, financial risk and anticipated rate of return. The current status of research and deveopment efforts in the US are also summarized.
Date: January 1, 1980
Creator: Tester, J.W.
Partner: UNT Libraries Government Documents Department

Issues facing the developmt of hot dry rock geothermal resources

Description: Technical and economic issues related to the commercial feasibility of hot dry rock geothermal energy for producing electricity and heat will be discussed. Topics covered will include resource characteristics, reservoir thermal capacity and lifetime, drilling and surface plant costs, financial risk and anticipated rate of return.
Date: January 1, 1979
Creator: Tester, J.W.
Partner: UNT Libraries Government Documents Department

Simulation and optimization of hot dry rock geothermal energy conversion systems: process conditions and economics

Description: The Los Alamos Scientific Laboratory is currently engaged in a field program aimed at designing and testing man-made geothermal reservoirs in hot granitic formations of low permeability created by hydraulic fracturing. A very important segment of the program is concerned with defining and optimizing several parameters related to the performance of the reservoir and their impact on the potential commercial feasibility of the hot dry rock technique. These include effective heat transfer area, permeation water loss, depth to the reservoir, geothermal temperature gradient, reservoir temperature, mass flow rate, and geochemistry. In addition, the optimization of the energy end use system (process or district heating, electricity or cogeneration) is directly linked to reservoir performance and associated costs. This problem has been studied using several computer modeling approaches to identify the sensitivity of the cost of power to reservoir and generation plant parameters. Also examined were a variety of important economic elements including rate of return on invested capital, discount or interest rates, taxes, cash flow, energy selling price, plant and reservoir lifetime, drilling and surface plant costs, and royalties.
Date: January 1, 1978
Creator: Tester, J.W.
Partner: UNT Libraries Government Documents Department

Pressure transient testing of a manmade fractured geothermal reservoir: an examination of fracture versus matrix dominated flow effects

Description: 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.
Date: September 1, 1980
Creator: Fisher, H.N. & Tester, J.W.
Partner: UNT Libraries Government Documents Department

Hot dry rock energy extraction field test: 75 days of operation of a prototype reservoir at Fenton Hill, Segment 2 of Phase I

Description: Results from the first extensive field test of a man-made hot dry rock (HDR) geothermal reservoir in low permeability crystalline rock are presented. A reservoir with a small heat transfer area was utilized to study the characteristics of a prototype HDR system over a shortened lifetime. The resulting accelerated thermal drawdown was modeled to yield an effective area of 8000 m/sup 2/. In addition to the thermal effects, this test provided an opportunity to examine equipment operation, water permeation into the formation, geochemical interaction between the circulating fluid and the rock and flow characteristics including impedance and residence time distributions. Continuous monitoring for induced seismic effects showed that no activity to a Richter threshold of -1.0 was detected during the 75-day experiment.
Date: April 1, 1979
Creator: Tester, J.W. & Albright, J.N. (eds.)
Partner: UNT Libraries Government Documents Department

Development of hot dry rock resources

Description: The LASL Hot Dry Rock Geothermal Energy Project is the only U.S. field test of this geothermal resource. In the LASL concept, a man-made geothermal reservoir would be formed by drilling a deep hole into relatively impermeable hot rock, creating a large surface area for heat transfer by fracturing the rock hydraulically, then drilling a second hole to intersect the fracture to complete the circulation loop. In 1974, the first hole was drilled to a depth of 2929 m (9610 ft) and a hydraulic fracture was produced near the bottom. In 1975, a second hole was directionally drilled to intersect the fracture. Although the desired intersection was not achieved, a connection was made through which water was circulated. After a year's study of the fracture system, drilling began again in April 1977 and an improved connection was achieved. In September of 1977 a 5 MW (thermal) heat extraction and circulation experiment was conducted for 100 h as a preliminary test of the concept. An 1800-h circulation experiment was concluded on April 13, 1978 to determine temperature-drawdown, permeation water loss and flow characteristics of the pressurized reservoir, to examine chemistry changes in the circulating fluid, and to monitor for induced seismic effects.
Date: January 1, 1978
Creator: Pettitt, R.A. & Tester, J.W.
Partner: UNT Libraries Government Documents Department

Environmental impacts of ocean disposal of CO{sub 2}. Fifth quarterly progress report, July 1, 1995--September 30, 1995

Description: The workshop had two major components: a review of current issues and projects regarding dissolution Of CO{sub 2} in the ocean followed by a specific proposal for a field experiment in a Norwegian fjord. Attachment I contains the agenda and participants for the meeting. Attachment II summarizes each presentation. The challenge of ocean dissolution Of CO{sub 2} involves understanding the trade-offs between costs, benefits (length Of CO{sub 2} sequestration), and environmental impacts (both from direct CO{sub 2} injection and from indirect dissolution as is occurring today). It is quite apparent that we still require a great deal more information than exists today to make rational decisions. Specifically, we need more research directed at the technology for dissolving the CO{sub 2} and at understanding the environmental impacts. While paper studies and laboratory experience are useful, we are approaching the time to move our research into the field. While attendees thought a field experiment in a Norwegian fjord would be a useful exercise, two key concerns were aired: (1) We need to better understand the goals of this experiment and how it relates to the bigger picture. To address this concern a comprehensive list of research needs should be generated. Then, a list of possible field experiments (including the Norwegian fjord) should be generated that allow us to address these questions. (2) Not enough details were presented on the Norwegian fjord experiment. For example, a key question is the scale (i.e. CO{sub 2} flow rate, duration) of the experiment. A follow-up action is to generate a more detailed experimental plan. In summary, the workshop left the following impressions. (3) More research is required to understand the role CO{sub 2} dissolution in the ocean can lay in mitigating global climate change. Field experiments will be required and the timing should be soon. (4) ...
Date: February 1, 1996
Creator: Tester, J.W. & Adams, E.E.
Partner: UNT Libraries Government Documents Department

Economics of a 75-MW(e) hot-dry-rock geothermal power station based upon the design of the Phase II reservoir at Fenton Hill

Description: Based upon EE-2 and EE-3 drilling costs and the proposed Fenton Hill Phase II reservoir conditions the break-even cost of producing electricity is 4.4 cents per kWh at the bus bar. This cost is based upon a 9-well, 12-reservoir hot dry rock (HDR) system producing 75 MW(e) for 10 yr with only 20% drawdown, and an assumed annual finance charge of 17%. Only one-third of the total, potentially available heat was utilized; potential reuse of wells as well as thermal stress cracking and augmentation of heat transfer was ignored. Nearly half the bus bar cost is due to drilling expenses, which prompted a review of past costs for wells GT-2, EE-1, EE-2, and EE-3. Based on comparable depth and completion times it is shown that significant cost improvements have been accomplished in the last seven years. Despite these improvements it was assumed for this study that no further advancements in drilling technology would occur, and that even in commercially mature HDR systems, drilling problems would continue nearly unabated.
Date: February 1, 1982
Creator: Murphy, H.; Drake, R.; Tester, J. & Zyvoloski, G.
Partner: UNT Libraries Government Documents Department

Economics of geothermal energy

Description: A selected summary is presented of the resource, technical, and financial considerations which influence the economics of geothermal energy in the US. Estimates of resource base and levelized busbar cost of base load power for several types of geothermal resources are compared with similar estimates for more conventional energy resources. Current geothermal electric power plants planned, under construction, and on-line in the US are noted.
Date: January 1, 1980
Creator: Morris, G.E.; Tester, J.W. & Graves, G.A.
Partner: UNT Libraries Government Documents Department

Vertebrate behavior and ecology. Progress report, July 1, 1977-May 31, 1980

Description: Engineering design and development concentrated on five aspects during the past year: (1) development of high power output transmitters for monitoring animals from greater distances; (2) improvement and updating of a sonic transmitting and receiving system for monitoring fish and marine mammals; (3) design and testing of corrosive links which permit a transmitter to release from an animal at a specified time; (4) development of high frequency transmitters; and (5) development and testing of time delay transmitters. Field efforts resulted in further information on activity patterns and movements of sea otters in California and Alaska and of walleye pike in experimental channels. Three manuscripts and two theses presented as part of this report describe these aspects in detail.
Date: June 1, 1980
Creator: Tester, J R & Siniff, D B
Partner: UNT Libraries Government Documents Department

Vertebrate behavior and ecology. Progress report, 1 July 1978--30 June 1979

Description: Efforts in engineering design and development this year emphasized improvement in the quality and versatility of radio transmitters, use of microprocessors in an automated fish tracking system, and construction of an automated system to monitor movements and activities of aquatic mammals in response to water temperature. Improved radio transmitters were used on a variety of species including sea otters, manatees, and wall-eyed pike. The fish tracking system, installed at Monticello, Minnesota, will next be modified for monitoring marine mammal movements. The temperature data logging system was tested on manatees in the St. John River near Blue Springs, Florida. The long-term goal in the subproject on evaluation of census methods is to utilize the extensive experience, technology, and equipment developed over the years in radio telemetry to resolve basic problems in animal census and population study methods. During the past year, efforts have resulted in information on activity patterns and the behavioral repertoire of sea otters and on the response of otters to contamination by Alaskan crude oil. Three preliminary manuscripts presented as part of this report describe these aspects in detail.
Date: July 1, 1979
Creator: Tester, J.R. & Siniff, D.B.
Partner: UNT Libraries Government Documents Department

Hot Dry Rock geothermal energy--- A new energy agenda for the twenty-first century

Description: Hot Dry Rock (HDR) geothermal energy, which utilizes the natural heat contained in the earth's crust, can provide a widely available source of nonpolluting energy. It can help mitigate the continued warming of the earth through the ''greenhouse effect,'' and the accelerating destruction of forests and crops by acid rain, two of the major environmental consequences of our ever-increasing use of fossil fuels for heating and power generation. In addition, HDR, as a readily available source of indigenous energy, can reduce our nation's dependence on imported oil, enhancing national security and reducing our trade deficit. The earth's heat represents an almost unlimited source of energy that can begin to be exploited within the next decade through the HDR heat-mining concept being actively developed in the United States and in several other countries. On a national scale, we can begin to develop this new energy source, using it directly for geothermal power or indirectly in hybrid geothermal/fossil-fueled systems, in diverse applications such as: baseload power generation, direct heat use, feedwater heating in conventional power plants, and pumped storage/load leveling power generation. This report describes the nature of the HDR resource and the technology required to implement the heat-mining concept in several applications. An assessment of the requirements for establishing HDR feasibility is presented in the context of providing a commercially competitive energy source. 37 refs., 6 figs.
Date: July 1, 1989
Creator: Tester, J.W.; Brown, D.W. & Potter, R.M.
Partner: UNT Libraries Government Documents Department

Interwell tracer analyses of a hydraulically fractured granitic geothermal reservoir

Description: Field experiments using fluorescent dye and radioactive tracers (Br{sup 82} and I{sup 131}) have been employed to characterize a hot, low-matrix permeability, hydraulically-fractured granitic reservoir at depths of 2440 to 2960 m (8000 to 9700 ft). Tracer profiles and residence time distributions have been used to delineate changes in the fracture system, particularly in diagnosing pathological flow patterns and in identifying new injection and production zones. The effectiveness of one- and two-dimensional theoretical dispersion models utilizing single and multiple porous, fractured zones with velocity and formation dependent effects are discussed with respect to actual field data.
Date: January 1, 1979
Creator: Tester, J.W.; Potter, R.M. & Bivins, R.L.
Partner: UNT Libraries Government Documents Department

Comparison of two hot dry rock geothermal reservoirs

Description: Two hot dry rock (HDR) geothermal energy reservoirs were created by hydraulic fracturing of granite at 2.7 to 3.0 km (9000 to 10,000 ft) at the Fenton Hill site, near the Valles Caldera in northern New Mexico. Both reservoirs are research reservoirs, in the sense that both are fairly small, generally yielding 5 MWt or less, and are intended to serve as the basic building blocks of commercial-sized reservoirs, consisting of 10 to 15 similar fractures that would yield approximately 35 MWt over a 10 to 20 yr period. Both research reservoirs were created in the same well-pair, with energy extraction well number 1 (EE-1) serving as the injection well, and geothermal test well number 2 (GT-2) serving as the extraction, or production, well. The first reservoir was created in the low permeability host rock by fracturing EE-1 at a depth of 2.75 km (9020 ft) where the indigenous temperature was 185/sup 0/C (364/sup 0/F). A second, larger reservoir was formed by extending a small, existing fracture at 2.93 km (9620 ft) in the injection well about 100 m deeper and 10/sup 0/C hotter than the first reservoir. The resulting large fracture propagated upward to about 2.6 km (8600 ft) and appeared to Rave an inlet-to-outlet spacing of 300m (1000 ft), more then three times that of the first fracture. Comparisons are made with the first reservoir. Evaluation of the new reservoir was accomplished in two steps: (1) with a 23-day heat extraction experiment that began October 23, 1979, and (2) a second, longer-term heat extraction experiment still in progress, which as of November 25, 1980 has been in effect for 260 days. The results of this current experiment are compared with earlier experiments.
Date: January 1, 1980
Creator: Murphy, H.D.; Tester, J.W. & Potter, R.M.
Partner: UNT Libraries Government Documents Department

Reservoir sizing using inert and chemically reacting tracers

Description: Non-reactive tracer tests in prototype hot dry rock (HDR) geothermal reservoirs indicate multiple fracture flow paths that show increases in volume due to energy extraction. Tracer modal volumes correlate roughly with estimated reservoir heat-transfer capacity. Chemically reactive tracers are proposed which will map the rate of advance of the cooled region of an HDR reservoir, providing advanced warning of thermal drawdown. Critical parameters are examined using a simplified reservoir model for screening purposes. Hydrolysis reactions are a promising class of reactions for this purpose.
Date: January 1, 1984
Creator: Robinson, B.A.; Tester, J.W. & Brown, L.F.
Partner: UNT Libraries Government Documents Department

Thermal conductivity of rocks associated with energy extraction from hot dry rock geothermal systems

Description: Results of thermal conductivity measurements are given for 14 drill core rock samples taken from two exploratory HDR geothermal wellbores (maximum depth of 2929 m (9608 ft) drilled into Precambrian granitic rock in the Jemez Mountains of northern New Mexico. These samples have been petrographically characterized and in general represent fresh competent Precambrian material of deep origin. Thermal conductivities, modal analyses, and densities are given for all core samples studied under dry and water-saturated conditions. Additional measurements are reported for several sedimentary rocks encountered in the upper 760 m (2500 ft) of that same region. A cut-bar thermal conductivity comparator and a transient needle probe were used for the determinations with fused quartz and Pyroceram 9606 as the standards. The maximum temperature range of the measurements was from the ice point to 250/sup 0/C. The measurements on wet, water-saturated rock were limited to the temperature range below room temperature. Conductivity values of the dense core rock samples were generally within the range from 2 to 2.9 W/mK at 200/sup 0/C. Excellent agreement was achieved between these laboratory measurements of thermal conductivity and those obtained by in situ measurements used in the HDR wellbores. By using samples of sufficient thickness to provide a statistically representative heat flow path, no difference between conductivity values and their temperature coefficients for orthogonal directions (heat flow parallel or perpendicular to core axis) was observed. This isotropic behavior was even found for highly foliated gneissic specimens. Estimates of thermal conductivity based on a composite dispersion analysis utilizing pure minerallic phase conductivities and detailed modal analyses usually agreed to within 9 percent of the experimental values.
Date: January 1, 1978
Creator: Sibbitt, W.L.; Dodson, J.G. & Tester, J.W.
Partner: UNT Libraries Government Documents Department