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An update on standards for radiation in the environment and associated estimates of risk

Description: This presentation reviews current and proposed standards, recommendations, and guidances for limiting routine radiation exposures of the public, and estimates the risk corresponding to standards, recommendations, and guidances. These estimates provide a common basis for comparing different criteria for limiting public exposures to radiation, as well as hazardous chemicals.
Date: June 21, 1989
Creator: Kocher, D.C.
Partner: UNT Libraries Government Documents Department

The theory of hybrid stochastic algorithms

Description: These lectures introduce the family of Hybrid Stochastic Algorithms for performing Monte Carlo calculations in Quantum Field Theory. After explaining the basic concepts of Monte Carlo integration we discuss the properties of Markov processes and one particularly useful example of them: the Metropolis algorithm. Building upon this framework we consider the Hybrid and Langevin algorithms from the viewpoint that they are approximate versions of the Hybrid Monte Carlo method; and thus we are led to consider Molecular Dynamics using the Leapfrog algorithm. The lectures conclude by reviewing recent progress in these areas, explaining higher-order integration schemes, the asymptotic large-volume behaviour of the various algorithms, and some simple exact results obtained by applying them to free field theory. It is attempted throughout to give simple yet correct proofs of the various results encountered. 38 refs.
Date: November 21, 1989
Creator: Kennedy, A.D. (Florida State Univ., Tallahassee, FL (USA). Supercomputer Computations Research Inst.)
Partner: UNT Libraries Government Documents Department

Near-Term Developments in Geothermal Drilling

Description: The DOE Hard Rock Penetration program is developing technology to reduce the costs of drilling geothermal wells. Current projects include: R & D in lost circulation control, high temperature instrumentation, underground imaging with a borehole radar insulated drill pipe development for high temperature formations, and new technology for data transmission through drill pipe that can potentially greatly improve data rates for measurement while drilling systems. In addition to this work, projects of the Geothermal Drilling Organization are managed. During 1988, GDO projects include developments in five areas: high temperature acoustic televiewer, pneumatic turbine, urethane foam for lost circulation control, geothermal drill pipe protectors, an improved rotary head seals.
Date: March 21, 1989
Creator: Dunn, James C.
Partner: UNT Libraries Government Documents Department

Hot Dry Rock Overview at Los Alamos

Description: The Hot Dry Rock (HDR) geothermal energy program is a renewable energy program that can contribute significantly to the nation's balanced and diversified energy mix. Having extracted energy from the first Fenton Hill HDR reservoir for about 400 days, and from the second reservoir for 30 days in a preliminary test, Los Alamos is focusing on the Long Term Flow Test and reservoir studies. Current budget limitations have slowed preparations thus delaying the start date of that test. The test is planned to gather data for more definitive reservoir modeling with energy availability or reservoir lifetime of primary interest. Other salient information will address geochemistry and tracer studies, microseismic response, water requirements and flow impedance which relates directly to pumping power requirements. During this year of ''preparation'' we have made progress in modeling studies, in chemically reactive tracer techniques, in improvements in acoustic or microseismic event analysis.
Date: March 21, 1989
Creator: Berger, Michael & Hendron, Robert H.
Partner: UNT Libraries Government Documents Department

Hot Dry Rock Geothermal Reservoir Model Development at Los Alamos

Description: Discrete fracture and continuum models are being developed to simulate Hot Dry Rock (HDR) geothermal reservoirs. The discrete fracture model is a two-dimensional steady state simulator of fluid flow and tracer transport in a fracture network which is generated from assumed statistical properties of the fractures. The model's strength lies in its ability to compute the steady state pressure drop and tracer response in a realistic network of interconnected fractures. The continuum approach models fracture behavior by treating permeability and porosity as functions of temperature and effective stress. With this model it is practical to model transient behavior as well as the coupled processes of fluid flow, heat transfer, and stress effects in a three-dimensional system. The model capabilities being developed will also have applications in conventional geothermal systems undergoing reinjection and in fractured geothermal reservoirs in general.
Date: March 21, 1989
Creator: Robinson, Bruce A. & Birdsell, Stephen A.
Partner: UNT Libraries Government Documents Department

Technology Transfer and the Product Development Process

Description: It is my pleasure this morning to address a topic that is much talked about in passing but rarely examined from a first person point of view. That topic is Technology Transfer. Over the next 30 minutes I'd like to approach Technology Transfer within the context of the Product Development Process looking at it from the perspectives of the federal government researcher and the industry manufacturer/user. Fist let us recognize that we are living in an ''Information Age'', where global economic and military competition is determined as much by technology as it is by natural resource assets. It is estimated that technical/scientific information is presently growing at a rate of l3 percent per year; this is expected to increase to 30 percent per year by the turn of the century. In fact, something like 90 percent of all scientific knowledge has been generated in the last 30 years; this pool will double again in the next 10-15 years (Exhibit 1). Of all the scientists and engineers throughout history, 90% live and work in the present time. Successfully managing this technical information/knowledge--i.e., transforming the results of R&D to practical applications--will be an important measure of national strength. A little over a dozen years ago, the United States with only 5 percent of the world's population was generating approximately 75 percent of the world's technology. The US. share is now 50 percent and may decline to 30 percent by the turn of the century. This decline won't be because of downturn in U.S. technological advances but because the other 95 percent of the world's population will be increasing its contribution. Economic and military strength then, will be determined by how quickly and successfully companies, industries, and nations can apply new technological information to practical applications--i.e., how they manage technology transfer within the ...
Date: March 21, 1989
Creator: Mock, John E.
Partner: UNT Libraries Government Documents Department

Pleasant Bayou Operations Brazoria County, Texas

Description: This project will demonstrate the Hybrid Cycle Concept for electricity generation using geopressured-geothermal resources. The test is scheduled to be a minimum of one year, which may be extended. The majority of the equipment came from the DOE facility at East Mesa, CA. The hybrid cycle has been designed for 10,800 BPD brine and 220,000 SCFD of gas. The power output will be about one megawatt, which will be sold to Houston Lighting and Power Company. An important research objective is to determine the size and ultimate production capability of the geopressured-geothermal reservoir. The long-term deliverability of these type reservoirs is a significant factor in determining the ultimate economic capability of these systems.
Date: March 21, 1989
Creator: Eaton, B.A.; Featherston, C.R. & Meahl, T.E.
Partner: UNT Libraries Government Documents Department

Geothermal Prospects in a Shrinking Power Surplus

Description: The western power surplus is finite and electric load growth is persistent. Concerns about availability and environmental effects will overshadow life-cycle cost in selection of tomorrow's sources. Geothermal's growth and achievements qualify it as a preferred resource for the 1990s and beyond but its merits remain largely unknown in political and financial circles. Near-term needs include power sales contracts after 1990, improved comfort for banks and utilities with reservoir assessment techniques and mitigation of financial risks at pilot plants on new fields. Institutional, not technical, issues will dominate geothermal energy's growth, performance, image and utility relationships in the 1990s.
Date: March 21, 1989
Creator: Geyer, John D.
Partner: UNT Libraries Government Documents Department

Geothermal Direct Use Engineering and Design Guidebook Available for an Expanding Market

Description: The Geothermal direct use industry potential, growth trends, needs, and how they are being met, are addressed. The high potential for industry growth, coupled with a rapidly expanding use of geothermal energy for direct use, and concerns over the greenhouse effect is the setting in which a new engineering and design guidebook is being issued to support the growth of the geothermal direct use industry. Recent investigations about the current status of the industry and the identification of technical needs of current operating district heating systems provide the basis upon which this paper and the guidebook is presented. The guidebook, prepared under the auspices of the U.S. Department of Energy, attempts to impart a comprehensive understanding of information important to the development of geothermal direct use projects. The text is aimed toward the engineer or technical person responsible for project design and development. The practical and technical nature of the guidebook answers questions most commonly asked in a wide range of topics including geology, exploration, well drilling, reservoir engineering, mechanical engineering, cost analysis, regulations, and environmental aspects.
Date: March 21, 1989
Creator: Lunis, Ben C. & Lienau, Paul J.
Partner: UNT Libraries Government Documents Department

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

Description: The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant part of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Fall in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studies we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated with the development and exploitation of geothermal resources.
Date: March 21, 1989
Creator: Lippmann, Marcelo J.
Partner: UNT Libraries Government Documents Department

GTO-DOE/Industry Cost Shared Research; Microseismic Characterization and Monitoring in Geothermal Systems

Description: The application of passive seismic studies in geothermal regions have undergone significant changes in the last 15 years. The primary application is now in the monitoring of subsurface processes, rather than exploration. A joint Geothermal Technology Organization (GTO) industry/DOE, monitoring project involving GEO, Unocal Geothermal, and LBL, was carried out at The Geysers geothermal field in northern California using a special high frequency monitoring system. This several-month-long experiment monitored the discrete and continuous seismic signals before, during, and after a fluid stimulation of a marginal production well. Almost 350,000 liters of water were pumped into the well over a four-hour, and a three-hour time period for two consecutive days in June of 1988. No significant changes in the background seismicity or the seismic noise were detected during the monitoring period. Analysis of the background seismicity did indicate that the earthquakes at The Geysers contain frequencies higher than 50 Hz. and possibly as high as 100 Hz.
Date: March 21, 1989
Creator: Majer, E.L.
Partner: UNT Libraries Government Documents Department

Drilling Operations Plan for the Magma Energy Exploratory Well

Description: This paper is a summary of the proposed drilling plan for the first phase (to 2500 feet depth) of the Magma Energy Exploratory Well. The drilling program comprises four phases, spaced approximately one year apart, which culminate in a large-diameter well to a total depth near 20,000 feet. Included here are descriptions of the well design, predictions of potential drilling problems, a list of restrictions imposed by regulatory agencies, an outline of Sandia's management structure, and an explanation of how the magma energy technology will benefit from this drilling.
Date: March 21, 1989
Creator: Finger, John T.; Livesay, Bill J. & Ash, Don
Partner: UNT Libraries Government Documents Department

Summary - Magma Energy R&D Strategies and Applications

Description: In this session, this vast resource of thermal energy was described by Dr. James C. Dunn (SNLA) as an estimated 500,000 quads in U.S. crustal magma bodies with temperatures in excess of 600 degrees Celsius and at depths of less than 10 km. The aim is to develop technology which can experimentally extract energy from a silicic magma body to demonstrate the feasibility of utilizing this resource. Energy extraction from molten rock has been demonstrated in Hawaii at the Kilauea Iki lava lake. The program is showing significant progress in Geophysics and Site Selection, Energy Extraction Processes, and Geochemistry/Materials. The next major step is to drill and evaluate a deep exploratory well at the Long Valley caldera in California. Extensive analyses by the program and from previous work indicate that active magma may be expected. John T. Finger (SNLA) then summarized the proposed four-phase drilling plan. The four phases will be approximately one year apart, and are expected to result in a large diameter well to a total depth of about 20,000 feet. The well design (by Livesay, Inc.) was described in considerable detail, together with predictions of the expected drilling problems. The well design and schedule includes accommodation of not only a substantial time for both program and outside experiments, but also the restrictions imposed by regulatory agencies including noise, disposal of wastes, and consideration of wildlife migratory patterns. Last, but hardly least, was a relation of the well and its drilling to the benefits to be accrued to the magma energy technology. The deep borehole measurements which can, and will be taken at the Long Valley well present a unique opportunity to test and validate geophysical techniques for locating magma, analyzing the geophysical parameters of the site and testing the theory that magma is still present at drillable ...
Date: March 21, 1989
Creator: Tennyson, George P. Jr.
Partner: UNT Libraries Government Documents Department

Advanced Binary Geothermal Power Plancts Working Fluid Property Determination and Heat Exchanger Design

Description: The performance of binary geothermal power plants can be improved through the proper choice of a working fluid, and optimization of component designs and operating conditions. This paper reviews the investigations at the Idaho National Engineering Laboratory (INEL) which are examining binary cycle performance improvements: for moderate temperature (350 to 400 F) resources with emphasis on how the improvements may be integrated into design of binary cycles. These investigations are examining performance improvements resulting from the supercritical vaporization of mixed hydrocarbon working fluids and achieving countercurrent integral condensation with these fluids, as well as the modification of the turbine inlet state points to achieve supersaturated turbine vapor expansions. For resources where the brine outlet temperature is restricted, the use of turbine exhaust recuperators is examined. The baseline plant used to determine improvements in plant performance (characterized by the increase in the net brine effectiveness, watt-hours per pound of brine) in these studies operates at conditions similar to the 45 MW Heber binary plant. Through the selection of the optimum working fluids and operating conditions, achieving countercurrent integral condensation, and allowing supersaturated vapor expansions in the turbine, the performance of the binary cycle (the net brine effectiveness) can be improved by 25 to 30% relative to the baseline plant. The design of these supercritical Rankine-cycle (Binary) power plants for geothermal resources requires information about the potential working fluids used in the cycle. In addition, methods to design the various components, (e.g., heat exchangers, pumps, turbines) are needed. This paper limits its view of component design methods to the heat exchangers in binary power plants. The design of pumps and, turbines for these working fluids presents no new problems to the turbine manufacturer. However, additional work is proceeding at the Heat Cycle Research Facility to explore metastable expansions within turbines. This work, ...
Date: March 21, 1989
Creator: Bliem, C.J. & Mines, G.L.
Partner: UNT Libraries Government Documents Department

Reservoir Modeling for Production Management

Description: For both petroleum and geothermal resources, many of the reservoirs are fracture dominated--rather than matrix-permeability controlled. For such reservoirs, a knowledge of the pressure-dependent permeability of the interconnected system of natural joints (i.e., pre-existing fractures) is critical to the efficient exploitation of the resource through proper pressure management. Our experience and that reported by others indicates that a reduction in the reservoir pressure sometimes leads to an overall reduction in production rate due to the ''pinching off'' of the joint network, rather than the anticipated increase in production rate. This effect occurs not just in the vicinity of the wellbore, where proppants are sometimes employed, but throughout much of the reservoir region. This follows from the fact that under certain circumstances, the decline in fracture permeability (or conductivity) with decreasing reservoir pressure exceeds the far-field reservoir ''drainage'' flow rate increase due to the increased pressure gradient. Further, a knowledge of the pressure-dependent joint permeability could aid in designing more appropriate secondary recovery strategies in petroleum reservoirs or reinjection procedures for geothermal reservoirs.
Date: March 21, 1989
Creator: Brown, Donald W.
Partner: UNT Libraries Government Documents Department

Deep Borehole Measurements for Characterizing the Magma/Hydrothermal System at Long Valley Caldera, CA

Description: The Magma Energy Program of the Geothermal Technology Division is scheduled to begin drilling a deep (6 km) exploration well in Long Valley Caldera, California in 1989. The drilling site is near the center of the caldera which is associated with numerous shallow (5-7 km) geophysical anomalies. This deep well will present an unparalleled opportunity to test and validate geophysical techniques for locating magma as well as a test of the theory that magma is still present at drillable depths within the central portion of the caldera. If, indeed, drilling indicates magma, the geothermal community will then be afforded the unique possibility of examining the coupling between magmatic and hydrothermal regimes in a major volcanic system. Goals of planned seismic experiments that involve the well include the investigation of local crustal structure down to depths of 10 km as well as the determination of mechanisms for local seismicity and deformation. Borehole electrical and electromagnetic surveys will increase the volume and depth of rock investigated by the well through consideration of the conductive structure of the hydrothermal and underlying regimes. Currently active processes involving magma injection will be studied through observation of changes in pore pressure and strain. Measurements of in situ stress from recovered cores and hydraulic fracture tests will be used in conjunction with uplift data to determine those models for magmatic injection and inflation that are most applicable. Finally, studies of the thermal regime will be directed toward elucidating the coupling between the magmatic source region and the more shallow hydrothermal system in the caldera fill. To achieve this will require careful logging of borehole fluid temperature and chemistry. In addition, studies of rock/fluid interactions through core and fluid samples will allow physical characterization of the transition zone between hydrothermal and magmatic regimes.
Date: March 21, 1989
Creator: Carrrigan, Charles R.
Partner: UNT Libraries Government Documents Department

Critique of Drilling & Completion Areas

Description: I am pleased with the research support provided by DOE, as it has resulted in products that are in use today, which reduce our cost of producing energy. Since we must compete in the energy market against other energy sources, such as coal, we needed to be cost competitive with these other sources. Research on these competitive sources will lower their costs in the future. We need to progress in our research to remain competitive. One question is whether the current DOE program will continue to provide the level of research advances we have benefited from in the past, even though the level of funding is significantly less. I believe that the funding level is too low if we want to maintain the same technology development pace. Ignoring the funding level, the remaining question is whether the highest priority projects (by industry's definition) are the ones being worked on by DOE. There is a mix of medium-term and long-term projects in the DOE Drilling and Completion program (about 30% short/70% long). I believe that industrial research would operate with these percentages reversed, and the preference for more short-term research is manifested by questioning the appropriateness of HDR & Magma research. Looking at the short-term projects such as lost circulation, waste handling, materials improvements and GDO projects, I think DOE is working on industry's major drilling and completion cost problems. If I look at the long-term projects, some of them--radar fracture mapping, cements, data telemetry--have obvious application to hydrothermal development, while the hydrothermal application of some of the others (such as magma convection) is not as apparent.
Date: March 21, 1989
Creator: Pye, Stephen
Partner: UNT Libraries Government Documents Department

Critique of "Fluid Production" R&D for Geothermal Program Review VII

Description: The stated goal of Geothermal Technology Division (GTD's) research program is to provide technical solutions required to establish all forms of this resource as long-term competitive energy alternatives. Especially at a time when the research budget is relatively small and competitive energy alternatives are relatively cheap, the emphasis on achieving tangible economic benefits through research is appropriate. In the case of a new technology such as tapping magma energy, it is too early to fine-tune the economics, but the research is well-justified by the magnitude of the potential resource. For projects aimed at incremental improvements in processes that are already commercial, economic potential is more easily defined. Fluid production research generally falls in the latter category. In keeping with the foregoing, it would be desirable for the research program participants to place greater emphasis on the potential applications and economic impact of their respective projects. Specifically, with regard to research projects aimed at improving the economics of existing commercial operations, the following points should be addressed: (1) in what resources, or types of resources, would the research results be applicable; (2) what are the best commercially available materials or techniques available, and how will the results of research improve operations in a tangible way; and (3) what are the future plans for each project, including plans for technology transfer? This would improve our understanding of the applicability of the research. Most presentations by researchers included progress summaries from the beginning of the project. These are important to the understanding of the projects. However, in many cases, there was no clear indication of what results were achieved within the last year. Because it is an annual Program Review, it would be appropriate to identify and emphasis the last year's results.
Date: March 21, 1989
Creator: Verity, Robert V.
Partner: UNT Libraries Government Documents Department

Properties of Geopressured Brines and Wells in the Gulf Coast and Opportunities for Industrial/Research Participation

Description: Geopressured reservoirs exhibit pressure gradients in excess of the normal hydrostatic gradient. In the Gulf Coast area the normal gradient is 0.465 psi/ft. Pressures may approach lithostatic pressure and have been measured as high as 1.05 psi/ft in the Gulf Coast area. Geopressured basins exist worldwide and in a number of U.S. locations, east, west, north and south. The Gulf Coast area has been studied extensively and is the subject of the DOE geopressured-geothermal research at present. The assumed ranges in resource characteristics include: depth from -12,000 to > -20,000 feet, brine flow rate from 20,000 to 40,000 bpd, temperature from 300 to 400 F, bottomhole pressure from 12,000 to 18,500 psi; salinity from 20,000 to 200,000 mg/L, gas-water ratio from 40 to 80 scf/bbl., and condensate from a trace to production. Energy in the geopressured resource includes gas, thermal, and hydraulic energy. It has been estimated that there are 6,000 quads of methane and 11,000 quads of thermal energy in the Gulf Coast area geopressured-geothermal reservoirs. Estimates run as high as 50,000 quad for the thermal energy (Wallace et al, 1978). Present industrial interest in the Pleasant Bayou and Hulin wells includes: desalination plants, an economic study by a power company for regional use, use of generated electricity by a coalition of towns, aquaculture (catfish farming) research program, and an unsolicited proposal for enhanced oil recovery of heavy oil. Direct uses of the hot brine cover dozens of industries and processes. An example of multiple uses in the USSR is shown. Outside agency interest includes the U.S.G.S., N.S.F., G.R.I., and possibly other areas within DOE. A research spin-off: a sensitive in-line benzene monitor has been designed by USL and will be tested in the near future. An in-line pH monitor is also under development for the harsh conditions of ...
Date: March 21, 1989
Creator: Wys, J. Nequs- de
Partner: UNT Libraries Government Documents Department

An Overview of Recent Logging Research at The University of Texas Petroleum Engineering Department

Description: Logging research at The University of Texas has been carried out in several areas. We have studied how rock resistivity varies with water saturation when other variables, such as rock wettability, stress, saturation history, and shale content are varied. Both experimental and theoretical work have been done. Rock wettability (oil or water wet) has by far the largest effect. Shale content and saturation history are also important. Rock stress is the least important, at least in the Berea sandstones and glass bed packs we have studied. We have published several papers and theses which describe this work in detail. We have also studied the effect of certain trace elements (boron, mainly) on the neutron log. Boron has a very high thermal neutron capture cross Section. Analyses of a number of Frio formation cores from the Texas Gulf Coast area show that boron occurs frequently in these rocks in amounts (up to 100 ppm or more) that would seriously affect several procedures in neutron log interpretation. It could, for example, reduce or even eliminate the neutron log--density log porosity reversal that is commonly used as a gas indicator. A recent paper reports details of our work in the Frio. We are currently extending our trace element studies to the West Texas area. The lower porosities occurring there make a given boron content in the rock even more important than in the higher porosity Gulf Coast area. Another effort has been the application of logging data to obtain better estimates of rock type, and inferentially, rock permeability. The work is semi-empirical, and results are usually limited in application geographically. These results can be very important, however; for example, when extrapolating core data to parts of a field where no cores were taken. Several papers have reported details of this work, which is ...
Date: March 21, 1989
Creator: Dunlap, H. F.
Partner: UNT Libraries Government Documents Department

Optimization of Injection Scheduling in Geothermal Fields

Description: This study discusses the application of algorithms developed in Operations Research to the optimization of brine reinjection in geothermal fields. The injection optimization problem is broken into two sub-problems: (1) choosing a configuration of injectors from an existing set of wells, and (2) allocating a total specified injection rate among chosen injectors. The allocation problem is solved first. The reservoir is idealized as a network of channels or arcs directly connecting each pair of wells in the field. Each arc in the network is considered to have some potential for thermal breakthrough. This potential is quantified by an arc-specific breakthrough index, b{sub ij}, based on user-specified parameters from tracer tests, field geometry, and operating considerations. The sum of b{sub ij}-values for all arcs is defined as the fieldwide breakthrough index, B. Injection is optimized by choosing injection wells and rates so as to minimize B subject to constraints on the number of injectors and the total amount of fluid to be produced and reinjected. The use of the various methods is demonstrated with reference both to hypothetical data and an actual data set from the Wairakei Geothermal Field in New Zealand.
Date: March 21, 1989
Creator: Lovekin, James & Horne, Roland N.
Partner: UNT Libraries Government Documents Department

An Organized Effort to Develop the Hydrothermal Energy Resource

Description: As a response to America's need for Alternate Energy sources, the U.S. Department of Energy has a Geothermal Program. Within this program is a Hydrothermal category. Currently, a wide range of tasks are being addressed as part of the Hydrothermal Program. The tasks include Industrialization, Reservoir Technology, Hard Rock Penetration and Conversion Technology. It is thought that successes already made in this program combined with upcoming successes will increase the likelihood of geothermal energy becoming a contributor to our nations future energy needs.
Date: March 21, 1989
Creator: Taylor, Kenneth J.
Partner: UNT Libraries Government Documents Department

Recent Developments in Geology, Geochemistry and Geophysics Applied to Hydrothermal Reservoir Mapping and Monitoring

Description: Progress in research and development of four of UURI's projects are reviewed in this paper. First, the development of chemical tracers has evolved to a field test in the Dixie Valley geothermal system in Nevada. Second, the measurement of in situ stress continues to demonstrate changes with location in the orientation of stress within active geothermal systems. Third, we continue to develop hydrologic models of geothermal systems based upon fluid inclusion measurements. Fourth, we are developing equipment that will allow testing of borehole to borehole and borehole to surface electrical resistivity techniques for locating fluid-filled fractures.
Date: March 21, 1989
Creator: Moore, Joseph N.; Nielson, Dennis L. & Wright, Phillip M.
Partner: UNT Libraries Government Documents Department

Prediction of Scaling in Geothermal Systems

Description: One of the main objectives of the DOE Geothermal Program is to improve the efficiency and reliability of geothermal operations so that this renewable form of energy can be integrated into the nation's energy system. Scale formation and other chemical problems associated with energy extraction from high temperature brines frequently inhibit the economical utilization of geothermal resources. In some cases, these chemical problems can be so severe that development of a site must be abandoned after considerable capital investment. The goal of our research efforts is to construct an accurate computer model for describing the chemical behavior of geothermal brines under a wide range of operating conditions. This technology will provide industry a cost-effective means of identifying scaling problems in production and reinjection wells as well as in surface equipment, and also devising and testing methods for well as other uses described in table (1) can contribute significantly to meeting the objectives of the Geothermal Program. The chemical model we have developed to date can simulate calcium carbonate scale formation and gas solubilities in concentrated brines containing sodium, potassium, calcium, chloride and sulfate ions as a function of temperature to 250 C and for variable partial pressure of CO{sub 2}. It can predict the solubility of other scale-forming minerals, such as amorphous silica, gypsum-anhydrite, halite and glasserite, as a function of brine composition to 250 C. The only required input for the model is the temperature, pressure and composition of the brine. Our modeling approach is based on semi-empirical thermodynamic descriptions of aqueous solutions. The model equations are parameterized by careful comparison to a variety of laboratory data. The ability of the resulting models to accurately predict the chemical behavior of even very concentrated high temperature brines is well demonstrated. This ability is an unusual feature of our models which ...
Date: March 21, 1989
Creator: Weare, John H. & Moller, Nancy E.
Partner: UNT Libraries Government Documents Department