6,636 Matching Results

Search Results

Advanced search parameters have been applied.

Permeability of Kayenta Sandstone to Hypersaline Brine at 10.3 MPa Confining Pressure and Temperatures to 90{degrees}C

Description: The ability to inject “spent” geothermal brine may be a critical and perhaps limited factor in the development of fluid-dominated geothermal resources. In order to understand and evaluate changes in formation permeability and porosity at depth as a result of injection of brine effluents, experiments were carried out (70°-90°C at 10.3 MPa confining pressure) in conjunction with the ongoing brine chemistry and materials evaluation effort at the Lawrence Livermore Laboratory Field Test Station located in the Salton Sea Geothermal Field, Imperial Valley, California. In summary, the data portrayed in Figure 1 indicate that large permeability losses occurred in Kayenta sandstone (porosity, 20.7 ± 1.66%) when unfiltered, untreated Magmamax brine and filtered, acidified Magmamax brine were the permeating fluids. In the former case, permeability decline was due to the accumulation of a thick filter cake on the top face of the core sample which was composed of amorphous silica and iron. In the latter situation, loss of permeability was caused by the precipitation of amorphous silica and generation of large quantities of calcite particles from the dissolution of the matrix cement. The experimental results thus show that if the Salton Sea Geothermal Field were composed of porous sedimentary formations similar to Kayenta sandstone, long-term injection of unmodified Magmamax brine is not feasible. In the case of acidified brine, most of the permeability decline may result from the mobilization of calcite. Additional experiments will be carried out in the future at lower flow rates to test the possibility of long-term injection of filtered, acidified geothermal brine. 6 refs., 1 tab., 1 fig.
Date: December 14, 1977
Creator: Piwinskii, A. J. & Netherton, R.
Partner: UNT Libraries Government Documents Department

Experimental verification of the load-following potential of a Hot Dry Rock geothermal reservoir

Description: A recent 6-day flow experiment conducted at the Los Alamos National Laboratory's Fenton Hill Hot Dry Rock (HDR) test site in north-central New Mexico has verified that an HDR reservoir has the capability for a significant, and very rapid, increase in power output upon demand. The objective of this cyclic load-following experiment was to investigate the performance of the reservoir in a nominal high-backpressure (2200 psi) baseload operating condition upon which was superimposed greatly increased power production for a 4-hour period each day. In practice, this enhanced production was accomplished by dropping the production well backpressure from the preexisting level of 2200 psi down to about 500 psi to rapidly drain the fluid stored in the pressure-dilated joints surrounding the production well. During the last cycle of this six-cycle test, the mean production conditions were 146.6 gpm for 4 hours at a temperature of 189°C followed by 92.4 gpm for 20 hours at a temperature of 183°C. These flow and temperature values indicate a flow enhancement of 59%, and a power enhancement of 65% during the high-production period. The time required to increase the reservoir power output from the baseload to the peaking rate was about 2 minutes.
Date: January 24, 1996
Creator: Brown, Donald
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 t o 3.0 km (5000 to 10000 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 t o 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. Evaluation of the second reservoir was accomplished in two steps: (1) with a 23-day heat extraction experiment that began October 23, 1979, the results of which are described by Murphy (1980), 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: December 16, 1980
Creator: Murphy, H. D.; Tester, J. W. & Potter, R. M.
Partner: UNT Libraries Government Documents Department

A Model of the Serrazzano Zone

Description: This paper discusses the lithology, structure, reservoir states and dynamics of the Serrazzano zone of the Lardarello Basin. Afterward, the author describes his progress in developing a mesh for use in modelling Serrazzano zone and shows its use in estimating initial heat and water reserves within the region modelled. 5 refs., 4 figs.
Date: December 14, 1977
Creator: Weres, Oleh
Partner: UNT Libraries Government Documents Department

Evaluating Geothermal Reserves with Application of Well Interference and Pressure Buildup Tests

Description: In order to evaluate geothermal reserves, it is necessary to estimate the porosity-thickness product of the reservoir. This paper deals with the method for estimating the porosity-thickness product of geothermal reservoirs by means of combining well interference and pressure buildup tests. A field study from the Chingshui geothermal area in Taiwan is given to illustrate the application of the method.
Date: December 15, 1983
Creator: Chiu, T.L.; Chiang, C.Y. & Wu, T.S.
Partner: UNT Libraries Government Documents Department

Exploration, Drilling and Development Operations in the Bottle Rock Area of the Geysers Steam Field, With New Geologic Insights and Models Defining Reservoir Parameters

Description: MCR Geothermal Corporation pioneered successful exploratiory drilling the Bottle Rock area of the Geysers Steam Field in 1976. The wellfield is characterized by a deep reservoir with varied flowrates, temperatures, pressures, and stem chemistries being quite acceptable. More detailed reservoir engineering tests will follow as production commences.
Date: December 15, 1983
Creator: Hebein, Jeffrey J.
Partner: UNT Libraries Government Documents Department

Hypotheses on Possible Equilibria Between N{sub2} and Other Gases at Larderello and Cerro Prieto

Description: Considering various possible chemical reactions between N{sub 2} and other gas species present in the geothermal fluid, the following reaction has been individuated: C + 1/2 N{sub 2} + 7/2 H{sub 2} = NH{sub 3} + CH{sub 4} which is generally satisfied for plausible thermodynamic reservoir conditions (temperature and the relative contributions of steam and liquid to fluid production) at Larderello and Cerro Prieto.
Date: December 15, 1983
Creator: D'Amore, Franco; Celati, Romano & Calore, Claudio
Partner: UNT Libraries Government Documents Department

A Status Report on the Exploitation Conditions of the Ahuachapan Geothermal Field

Description: The present exploitation conditions of the Ahuachapan field are discussed. The high well density in a small area has resulted in a significant reservoir pressure decrease due to the inherent reservoir over-exploitation. The average pressure in the exploitation zone has decreased from the 1975 value of 34 kg/cm{sup 2} to the May 1983 value of 23 kg/cm{sup 2}. The production decline characteristics of the Ahuachapan wells were examined, concluding that all wells but Ah-22 show exponential decline. The cumulative production-reinjection for the field up to April 1983 is 159.090 x 10{sup 6} tons, and 37.592 x 10{sup 6} tons, respectively. The effect of reinjection upon field behavior is evident when observing the pressure decline characteristics of the field. It is seen that for indection fraction related to total mass extracted above 30 percent, the average decline pressure in the production area becomes approximately stabilized. If this condition is not met the reservoir pressure decreases sharply. From this finding it is concluded that a careful and properly planned reinjection program is a must for the field. The observed temperature reduction in some of the wells seems to be the result of two operating mechanisms. First, we have the pressure decline that produces water vaporization and the consequent temperature descend. Analysis of information available shows no clear indication of deleterious temperature effects on the producing wells due to injection. The only exception observed to date is well Ah-5 that because its close distance and its relative structural position and direct hydraulic connection to injector Ah-29, presented conditions for fast displacement of the thermal front, resulting in unsufficient contact area and residence time for reheating of the injected water.
Date: December 15, 1983
Creator: Rivera-R., Jesus; Vides-R., Alberto; Cuellar, Gustavo; Samaniego-V., Fernando & Neri-I, Gustavo
Partner: UNT Libraries Government Documents Department

Geothermal Energy Development in China

Description: China's geothermal resources are mainly of low - medium temperature. More than 30 geothermal areas have been or are being explorated. According to the geology, economy and technology of geothermal energy development main efforts are concentrated in some places with better conditions and can be exploited effectively in the near future, such as low temperature geothermal fields in Beijing and Tianjin, Yangbajain and Dengchong high temperature geothermal fields respectively in Tibet and Ynnan province. In Beijing and Tianjin the geothermal water is used for space heating, bathing, medical treatment, greenhouse, raising tropical fish, industry and so on. In Beijing now more than 200 thousand sq. m. of indoor floor is being heated with geothermal water and about 50 thousand persons per day use it to take bath. In future, the low temperature geothermal water utilization in these big citites would flourish. In 1970 the first experimental geothermal power plant using the flashing method was built in Dengwu, Guangdong province. In 1977 one MW experimental wet steam power plant was built in Yangbajain, Tibet, a 6 MW power plant in 1981, and another 3 MW generator is expected to complete in 1985. This paper is intended to summarize some important results of exploration, particularly in the geothermal reservoir engineering.
Date: December 15, 1983
Creator: Kuide, Xin & Qilong, Yang
Partner: UNT Libraries Government Documents Department

Geothermal Field Development in Mexico

Description: Mexico is a Country characterized by its diversified means of Power Gerneration. Actual installed capacity is almost 19000 MW, of which 205 MW corresponds to Geothermal Plants, that is, 180 MW in Cerro Prieto and 25 MW of Portable Plants in Los Azufres. To date, 346 area with exploitation possibilites, are known. They are mainly distributed along the Volcanic Belt where the most prominent are, Los Azufres, La Primavera, Los Humeros, Ixtlan De Los Hervores and Los Negritos, among others. Proved reserves are 920 MW, and the accessible resource base are 4600 MW identified and 6000 MW undiscovered. The long range construction studies intends to achieve a total installed capacity of 100000 MW, by the end of this century, including 2000 MW Geothermal, through conventional and Portable Plants. It is not a definite program but a development strategy. The carrying out of a definite program, will depend upon the confirmation of Hypothesis made in previous studies, and the economic decisions related to the financial sources availability, and techologies to be used in the future as well.
Date: December 15, 1983
Creator: Espinosa, Hector Alonso
Partner: UNT Libraries Government Documents Department

Geothermal Field Development in the European Community Objectives, Achievements and Problem Areas

Description: Achievements and problem areas are reviewed with respect to various engineering implications of geothermal field development in the European Community (EC). Current and furture development goals address three resource settings. (a) low enthalpy sources (30-150{degrees}C), an outlook common to all Member states as a result of hot water aquifers flowing in large sedimentary units with normal heat flow, widespread thoughout the EC; (b) high enthalpy sources (<150{degrees}C) in areas of high heat flow which, as a consequence of the geodynamics of the Eurasian plate, are limited to Central and South-West Italy and to Eastern Greece; (c) hot dry rocks (HDR), whose potential for Europe, and also the difficulties in implementing the heat mining concept, are enormous. A large scale experiment conducted at medium depth in Cornwall (UK) proves encouraging though. It has provided the right sort of scientific inputs to the understanding of the mechanics of anisotropic brittle basement rocks.
Date: December 15, 1983
Creator: Ungemach, Pierre
Partner: UNT Libraries Government Documents Department

Geothermal Field Developments in Iceland

Description: The exploration and research carried out in conjunction with the exploitation of the various geothernal fields has vastly deepened our understanding of the hydrothermal systems in Inceland. They have proved to be more diverse with respect to physical state, chemical composition, hydrological properties, and geological control than previously thought. The purpose of the present paper is to review the present state of knowledge regarding the Icelandic geothermal systems, with emphasis on the production and reservoir engineering aspects.
Date: December 15, 1983
Creator: Palmason, G.; Stefansson, V.; Thorhallsson, S. & Thorsteinsson, T.
Partner: UNT Libraries Government Documents Department

Geothermal Field Developments in Japan

Description: The present situation of the geothermal field developments in Japan is such that eight geothermal power stations are being operated, while there are sill many geothermal areas to be explored. Up to this day, the target of geothermal exploration has mainly been the areas by surface geological survey and the existing geothermal reservoirs are located not deeper than 1,500m depth. Recent geothermal energy development shows a trend from the study on vapor dominated of liquid dominated hydrothermal resources in shallow zones to that on hydrothermal resources in deeper zones. Exploration wells of 3,000m depth class have been drilled in Japan.
Date: December 15, 1983
Creator: Hirakawa, Seiichi
Partner: UNT Libraries Government Documents Department

Reservoir Engineering Aspects of the Philippines Geothermal Developments in Leyte and Southern Negros

Description: The current state of development of the Tongonan and Puhagan geothermal fields in the Philippines is presented and the nature of the reservoirs is described. In the latter part of the paper, reservoir engineering techniques which have been found to be particularly valuable are discussed and some aspects which give rise to problems are identified.
Date: December 15, 1983
Creator: Kingston, R. & Watson, A.
Partner: UNT Libraries Government Documents Department

Multiple Reservoirs in the Mofete Field, Naples, Italy

Description: Mofete field, located near Naples, in southern Italy, lies within the large Campi Flegrei caldera. Drilling for geothermal fluids was carried out unsuccessfully in 1939-1954. AGIP, in joint venture with the national utility ENEL, after intensive exploration efforts, resumed drilling at the end of 1978; several new deep wells indicate the presence of a water dominated field in Mofete with three reservoirs (only the shallowest of which was reached by previous wells). The deepest aquifer, tapped by well Mofete 5 at the depth of about 2700 m, contains hypersaline fluids (about 516000 ppm TDS at atmospheric conditions corresponding to about 150000 ppm in the reservoir) with a bottom hole temperature of about 360{degrees}C. The intermediate level, reached by well Mofete 2 at 1900 m depth, is characterized by low salinity fluids (about 38000 ppm TDS at the surface corresponding to 18000 ppm calculated in the reservoir) with a reservoir temperature of 340{degrees}C. The uppermost reservoir, tapped by wells Mofete 1, 3D, 7D, 8D and 9D ranges between 550 and 1500 m depth and has water with salinity ranging from 40000 to 76000 ppm TDS at the surface corresponding to 28000 to 52000 ppm in the reservoir with a bottom temperature of 230-308{degrees}C. The uppermost aqifer is in fractured volcanic rocks while the other two are in a metamorphosed volcano-sedimentary complex. Long term production and injection tests will be carried out shortly to ascertain the main characteristics of the field.
Date: December 15, 1983
Creator: Carella, R. & Guglielminetti, M.
Partner: UNT Libraries Government Documents Department