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An experimental study of adsorption in vapor-dominated geothermal systems

Description: We report results of steam adsorption experiments conducted for rock samples from vapor-dominated geothermal reservoirs. We examine the effect of the temperature on the adsorption/desorption isotherms. We find that the temperature effect is only important on the desorption such that the hysteresis becomes more pronounced as the temperature increases. The scanning behavior within the steam sorption hysteresis loop is also studied to investigate the behavior during repressurization. Collection of sets of data on the sorption behavior of The Geysers geothermal field in California is presented.
Date: January 26, 1995
Creator: Satik, Cengiz & Horne, Roland N.
Partner: UNT Libraries Government Documents Department

Elimination of Heat-Shielding for Geothermal Tools Operating Up To 300 Degress Celsius

Description: This report focuses Sandia National Laboratories' effort to create high-temperature logging tools for geothermal applications not requiring heat-shielding. Tool electronics can operate up to 300 C with a few limiting components operating to 250 C. Second generation electronics are needed to increase measurement accuracy and extend the operating range to 300 and then 350 C are identified. Custom development of high-temperature batteries and assembling techniques are touched on. Outcomes of this work are discussed and new directions for developing high-temperature industry are suggested.
Date: October 7, 1999
Partner: UNT Libraries Government Documents Department

Evolution of downhole measurement systems

Description: An often-cited example of the need for technology development arises from the lack of downhole tools suitable for use in thermal regimes. But a more general reason for development stems from the nature of scientific drilling in that work is conducted in regions of the Earth`s crust that differ from the sedimentary regions of interest to the traditional logging industry. Thus, even well-established tools must be examined for data integrity and information content. Interactions between scientific drilling programs and industrial institutions can further this mission at a time when budgetary difficulties are manifest. These interactions will require guarantees that evolutionary systems are useful and practical; guidelines addressing such quality issues are under development within the Ocean Drilling Program. The purpose of this paper is to assess downhole measurements as they pertain to scientific programs, and to note where collaborative efforts may be initiated. First, generic issues of tool response to formation and borehole conditions are addressed because they apply to all measurement systems. The paper then deals with the particular case of high-temperature tools because such tools are evolving in scientific and industrial programs. The next section puts forth the need for rules governing the development of measurement systems, and presents the set of governing conditions that were recently adopted by the Ocean Drilling Program. Finally, a view to the future is made.
Date: January 1, 1993
Creator: Lysne, P.
Partner: UNT Libraries Government Documents Department

A study of geothermal drilling and the production of electricity from geothermal energy

Description: This report gives the results of a study of the production of electricity from geothermal energy with particular emphasis on the drilling of geothermal wells. A brief history of the industry, including the influence of the Public Utilities Regulatory Policies Act, is given. Demand and supply of electricity in the United States are touched briefly. The results of a number of recent analytical studies of the cost of producing electricity are discussed, as are comparisons of recent power purchase agreements in the state of Nevada. Both the costs of producing electricity from geothermal energy and the costs of drilling geothermal wells are analyzed. The major factors resulting in increased cost of geothermal drilling, when compared to oil and gas drilling, are discussed. A summary of a series of interviews with individuals representing many aspects of the production of electricity from geothermal energy is given in the appendices. Finally, the implications of these studies are given, conclusions are presented, and program recommendations are made.
Date: January 1, 1994
Creator: Pierce, K. G. & Livesay, B. J.
Partner: UNT Libraries Government Documents Department

Zinc(II) oxide stability in alkaline sodium phosphate solutions at elevated temperatures

Description: Zinc oxide (ZnO) is shown to transform into either of two phosphate-containing compounds in relatively dilute alkaline sodium phosphate solutions at elevated temperatures via ZnO(s) + Na{sup +} + H{sub 2}PO{sub 4}{sup {minus}} {r_reversible} NaZnPO{sub 4}(s) + H{sub 2}O or 2 ZnO(s) + H{sub 3}PO{sub 4}(aq) {r_reversible} Zn{sub 2}(OH)PO{sub 4}(s) + H{sub 2}O. X-ray diffraction analyses indicate that NaZnPO{sub 4} possesses an orthorhombic unit cell having lattice parameters a = 8.710 {+-} 0.013, b = 15.175 {+-} 0.010, and c = 8.027 {+-} 0.004 {angstrom}. The thermodynamic equilibria for these reactions were defined in the system ZnO-Na{sub 2}O-P{sub 2}O{sub 5}-H{sub 2}O for Na/P molar ratios between 2.1 and 3. Based on observed reaction threshold values for sodium phosphate concentration and temperature, the standard entropy (S{degrees}) and free energy of formation ({Delta}G{sub f}{degrees}) for NaZnPO{sub 4} were calculated to be 169.0 J/mol-K and {minus}1510.6 kJ/mol, respectively; similar values for Zn{sub 2}(OH)PO{sub 4} (tarbuttite) were 235.9 J/mol-K and {minus}1604.6 kJ/mol. Additions of sodium sulfite and sulfate did not alter the above reactions.
Date: April 1, 1993
Creator: Ziemniak, S. E. & Opalka, E. P.
Partner: UNT Libraries Government Documents Department