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Geothermal Energy Development

Description: The Nation has embarked on an aggressive program to develop its indigenous resources of geothermal energy. For more than a decade, geothermal energy has been heralded as one of the more promising forms of energy alternate to oil and gas for electric power generation, but during the last fifteen years, the total capacity in the U.S. has reached 502 MWe, about half the size of a single modern nuclear power plant. And yet, the United States, especially its western and Gulf coast states, is believed to possess a vast resource base of geothermal heat at depths up to 3 to 10 km. Many estimates of these potential resources suitable for the production of electric power have been published and they range over a spectrum of more than a factor of 100. This variation suggests that the potential is essentially unknown. Table 1 gives a range of published forecasts for the year 1985 and the equivalent potential in number of 1000 Mwe power plants and in oil consumption in millions of barrels per day. In view of the estimated construction of about 200 to 250 nuclear power reactors by 1985-90, the pessimistic forecasts clearly show that the contribution of geothermal energy to the Nation's energy supply may indeed be small. The optimistic forecasts represent more than 15% of the total electric power requirements estimated for the year 1985. The Task Force for Geothermal Energy, in the Federal Energy Administration Project Independence Blueprint report of November 1974, established a national goal for 1985 of 20,000 to 30,000 MWe, the latter value representing an equivalent energy supply of one million barrels of oil per day. This goal was clearly a compromise between what is worth a national effort and what might be realistically achieved. The potential for adding or replacing the equivalent of ...
Date: November 3, 1975
Creator: Kruger, Paul
Partner: UNT Libraries Government Documents Department

Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Description: Most current seismic methods to seismically characterize fractures in tight reservoirs depend on a few anisotropic wave propagation signatures that can arise from aligned fractures. While seismic anisotropy can be a powerful fracture diagnostic, a number of situations can lessen its usefulness or introduce interpretation ambiguities. Fortunately, laboratory and theoretical work in rock physics indicates that a much broader spectrum of fracture seismic signatures can occur, including a decrease in P- and S-wave velocities, a change in Poisson's ratio, an increase in velocity dispersion and wave attenuation, as well as well as indirect images of structural features that can control fracture occurrence. The goal of this project was to demonstrate a practical interpretation and integration strategy for detecting and characterizing natural fractures in rocks. The approach was to exploit as many sources of information as possible, and to use the principles of rock physics as the link among seismic, geologic, and log data. Since no single seismic attribute is a reliable fracture indicator in all situations, the focus was to develop a quantitative scheme for integrating the diverse sources of information. The integrated study incorporated three key elements: The first element was establishing prior constraints on fracture occurrence, based on laboratory data, previous field observations, and geologic patterns of fracturing. The geologic aspects include analysis of the stratigraphic, structural, and tectonic environments of the field sites. Field observations and geomechanical analysis indicates that fractures tend to occur in the more brittle facies, for example, in tight sands and carbonates. In contrast, strain in shale is more likely to be accommodated by ductile flow. Hence, prior knowledge of bed thickness and facies architecture, calibrated to outcrops, are powerful constraints on the interpreted fracture distribution. Another important constraint is that fracturing is likely to be more intense near faults--sometimes referred to as ...
Date: November 30, 2004
Creator: Mavko, Gary
Partner: UNT Libraries Government Documents Department

Seismic and Rockphysics Diagnostics of Multiscale Reservoir Textures

Description: As part of our study on ''Relationships between seismic properties and rock microstructure'', we have studied (1) Kerogen-rich shales using Scanning Acoustic Microscopy and ultrasonic wave propagation. We find that an increase in elastic modulus with increasing kerogen maturity can be directly related to the microstructural acoustic impedance changes. A positive relation is established between microstructural changes and velocity variations as functions of kerogen maturity. (2) Elastic properties of clay minerals using Atomic Force Acoustic Microscopy and Scanning Acoustic Microscopy. We show the effect of clay minerals in contact zones as load-bearing constituents of rocks (3) Elastic properties of unconsolidated sediments in an effort to quantify attributes for detection of overpressures from seismic and for effects of stress-induced velocity anisotropy in sediments (4) We have initiated efforts for velocity upscaling to quantify long-wavelength and short-wavelength velocity behavior and the scale-dependent dispersion caused by sediment variability in different depositional environments.
Date: November 1, 2002
Creator: Mavko, Gary
Partner: UNT Libraries Government Documents Department

Quantification of Hydrological, Geochemical, and Mineralogical Processes Governing the Fate and Transport of Uranium over Multiple Scales in Hanford Sediments

Description: A long-term measure of the DOE Environmental Remediation Sciences Division is to provide sufficient scientific understanding to allow a significant fraction of DOE sites to incorporate coupled biological, chemical, and physical processes into decision making for environmental remediation and long-term stewardship by 2015. Our research targets two related, major obstacles to understanding and predicting contaminant transport at DOE sites: the heterogeneity of subsurface geologic media, and the scale dependence of experimental and modeled results.
Date: November 15, 2006
Creator: Mayes, Melanie A.; Perfect, Edmund; van den Berg, Elmer; Parker, Jack C.; Jardine, Philip M.; Tang, Guoping et al.
Partner: UNT Libraries Government Documents Department

Quantification of Hydrological, Geochemical, and Mineralogical Processes Governing the Fate and Transport of Uranium over Multiple Scales in Hanford Sediments

Description: A long-term measure of the DOE Environmental Remediation Sciences Division is to provide sufficient scientific understanding to allow a significant fraction of DOE sites to incorporate coupled biological, chemical, and physical processes into decision making for environmental remediation and long-term stewardship by 2015. Our research targets two related, major obstacles to understanding and predicting contaminant transport at DOE sites: the heterogeneity of subsurface geologic media, and the scale dependence of experimental and modeled results.
Date: November 15, 2006
Creator: Fendorf, Scott; Mayes, Melanie A.; Perfect, Edmund; van den Berg, Elmer; Parker, Jack C.; Jardine, Philip M. et al.
Partner: UNT Libraries Government Documents Department

Progress and commissioning of the SLD Cherenkov Ring Imaging Detector

Description: We report the recent progress of the SLD Cherenkov Ring Imaging Detector. All of the individual components of the device (TPC's, mirrors, liquid radiator trays) have been completed and installed. Almost half of the electronics packages are installed and operational, and the data acquisition system has been commissioned. The liquid C{sub 6}F{sub 14} recirculation system is functioning. The drift gas supply systems are operating well with TMAE, and the gaseous Freon C{sub 5}F{sub 12} recirculator is being brought on-line. Our monitor and control systems are fully functional. The commissioning of all 40 TPCs at full operating voltage has gone very smoothly. The system shows a remarkable immunity to the SLC backgrounds, and yields very clean events, while operating with a single electron sensitivity.
Date: November 1, 1991
Creator: Abe, K.; Hasegawa, K.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D. et al.
Partner: UNT Libraries Government Documents Department

Size distributions of fly ash using Coulter Multisizer: Use of multiple orifices and fitting to truncated log-normal distributions. [Coulter Multisizer]

Description: Fly ash particles, which are predominantly spherical and glassy, are produced by melting of the mineral inclusions in the coal during combustion. Particle diameters can range from sub-micrometer (micron or {mu}m) to greater than 100 {mu}m. The size distribution of fly ash is needed to determine its role in the radiation transfer process in pulverized coal combustors. The Coulter Multisizer is an useful instrument for sizing powders with a broad size distribution. A single Multisizer orifice can size particles only within a specific size range limited at the lower end to a few percent of orifice diameter by sensitivity and at the upper end by increasing non-linearity of the signal-volume relation. A scheme for combining data obtained using orifices of different diameters is described. The manufacturers state that the smallest particle which can be sized accurately is nominally 2% of the diameter of the orifice. However, it was found that the data for particles less than 4% of the orifice diameter were not reliable. In order to use the smaller orifices, the larger particles have to be removed from the sample. A wet-sieving apparatus, designed for accurate separation of the particles by size, is described. A log-normal distribution function, truncated outside the measurement limits, fits the size distribution data well. Size parameters for fly ashes of six representative US coals are presented.
Date: November 1, 1991
Creator: Ghosal, S.; Ebert, J. L. & Self, S. A.
Partner: UNT Libraries Government Documents Department

Geochemical Controls on Nuclear Magnetic Resonance Measurements

Description: OAK-B135 Our research objectives are to determine, through an extensive set of laboratory experiments, the effect of the specific mineralogic form of iron and the effect of the distribution of iron on proton nuclear magnetic resonance (NMR) relaxation mechanisms. In the first nine months of this project, we have refined the experimental procedures to be used in the acquisition of the laboratory NMR data; have ordered, and conducted preliminary measurements on, the sand samples to be used in the experimental work; and have revised and completed the theoretical model to use in this project. Over the next year, our focus will be on completing the first phase of the experimental work where the form and distribution of the iron in the sands in varied.
Date: November 11, 2003
Creator: Knight, Rosemary; Prasad, Manika & Keating, Kristina
Partner: UNT Libraries Government Documents Department

Growth of high T{sub c} superconducting fibers using a miniaturized laser-heated float zone process. Annual progress report, October 15, 1989--November 5, 1990

Description: This report covers the research accomplished on the program entitled {open_quotes}Growth of High Tc Superconducting Fibers using a Miniaturized Laser-Heated Float Zone Process{close_quotes} during the 12.5 month period from Oct. 15, 1989 to Nov. 5, 1990. Research was done in four areas: phase relationships, preparation of starting materials, growth studies and the advanced fiber growth apparatus. The phase relationship studies built on the work published by Ono. Comparison studies with the well known compound Ca{sub 3}Al{sub 2}O{sub 6} confirmed that the Bi{sub 2+x}(Sr,Ca){sub 3-x}Cu{sub 2}O{sub y} is incongruently melting and that cuprous oxide, calcium oxide and (strontium, calcium) cuprate are the higher melting compounds which coexist with the melt and the superconducting phase. The preparation of the starting materials is crucial to the stable growth of the fibers. Non-uniform distribution of second phase particles, gaseous inclusions or porosity can lead to instabilities. A process was developed to ensure uniform starting materials. `Ibis process involves grinding the individual starting materials to a uniform size (44 {mu}m). The resulting powders are mixed and calcined three times with regrinding between each calcining step. The calcined powder is then cold pressed and sintered, reground, re-pressed and sintered. Ibis final material is then cut into bars for feed material for fiber growth. Growth rate studies showed a relationship between the growth rate and the regions of stability for single and multiphase fibers. This was traced to changes in the Bi and Cu levels in the melt related to changes in the growth rate. It was also shown that fluctuation in laser power lead to CaO inclusions in the fibers. The necessary components for the Advanced Fiber Growth Apparatus have been determined. Some of the components have been ordered and others are being designed.
Date: November 1, 1990
Creator: Feigelson, R.S.
Partner: UNT Libraries Government Documents Department

SEISMIC AND ROCKPHYSICS DIAGNOSTICS OF MULTISCALE RESERVOIR TEXTURES

Description: As part of our study on ''Relationships between seismic properties and rock microstructure'', we have continued our work on analyzing microstructural constraints on seismic signatures. Our analysis is now extended to over 280 images of shales, giving us better statistics. The shales cover a range of depths and maturity. We estimate different statistical measures for characterizing heterogeneity and textures from scanning acoustic microscope (SAM) images of shale microstructures. Characterizing and understanding the microgeometry, their textures, scales, and textural anisotropy is important for better understanding the role of microgeometry on effective elastic properties. We analyzed SAM images from Bakken shale, Bazhenov shale, and Woodford shale. We observed quantifiable and consistent patterns linking texture, shale maturity, and elastic P-wave impedance. The textural heterogeneity and P-wave impedance increase with increasing maturity (decreasing kerogen content), while there is a general decrease in textural anisotropy with maturity. We also found a reasonably good match between elastic impedance estimated from SAM images and impedance computed from ultrasonic measurements.
Date: November 1, 2004
Creator: Mavko, Gary
Partner: UNT Libraries Government Documents Department