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[en] Many geothermal convection systems, are situated at or near Plio-Quarternary volcanoes Azarbaidjan, and photogeologic interpretation is quite helpful in volcano-stratigraphic studies of these areas. Molten or solidified magma beneath such areas generally is accepted as the heat source for geothermal systems related to volcanoes. The volcanic activity of the East-Northeast zone had begun in Eocene time and continued into the plio-quarternary, with at least phases of folding Miocene (NM Mianeh) Pliocene (SW of Tabriz Town) and Pleistocene (Sahand to Savalan) Times. In Azarbaidjan, most hydrothermal convection systems are developed in areas related to Quarternary volcanism, and these systems are associated with surface activity such as hot springs, fumaroles, hydrothermal alteration, and anomalously high surface temperatures. Numerous hot springs usually occur in the Azarbaidjan. The zone of the springs extends from Savalan to Sahand towards Kamchi, Kantal and Ardoush in the border Aras River. (Author)
[en] After nearly two decades of geoscientific-exploration at 45 geothermal areas in the Philippines, the Philippine National Oil Company-Energy Development Corporation (PNOC-EDC) has developed a multi-disciplinary approach for exploring country's geothermal resources. It suitability for crater-hosted magmatic geothermal systems is currently being evaluated in the light of new data from six recently drilled prospects. New techniques are under consideration for future exploration programmes. (auth.). 59 refs.; 5 figs
[en] This report describes the work that was done to prepare the Phase II proposal for an enhanced geothermal system based on the use of horizontal well to increase production of reservoir fluids from geothermal wells
[en] The Caldes de Boí geothermal waters show important differences in pH (6.5–9.6) and temperature (15.9ºC–52ºC) despite they have a common origin and a very simple circuit at depth (4km below the recharge area level). Thes differences are the result of secondary processes such as conductive cooling, mixing with colder shallower waters, and input of external CO2, which affect each spring to a different extent in the terminal part of the thermal circuit. In this paper, the secondary processes that control the geochemical evolution of this system have been addressed using a geochemical dataset spanning over 20 years and combining different approaches: classical geochemical calculations and geochemical modelling. Mixing between a cold and a thermal end-member, cooling and CO2 exchange are the processes affecting the spring waters with different intensity over time. These differences in the intensity of the secondary processes could be controlled by the effect of climate and indirectly by the geomorphological and hydrogeological setting of the different springs. Infiltration recharging the shallow aquifer is dominant during the rainy seasons and the extent of the mixing process is greater, at least in some springs.Moreover, significant rainfall can produce a decrease in the ground temperature favouring the conductive cooling. Finally, the geomorphological settings of the springs determine the thickness and the hydraulic properties of the saturated layer below them and, therefore, they affect the extent of the mixing process between the deep thermal waters and the shallower cold waters. The understanding of the compositional changes in the thermal waters and the main factors that could affect them is a key issue to plan the future management of the geothermal resources of the Caldes de Boí system. Here, we propose to use a simple methodology to assess the effect of those factors, which could affect the quality of the thermal waters for balneotherapy at long-term scale. Furthermore, the methodology used in this study can be applied to other geothermal systems.
[en] Five core samples from two wells (LHD1 and LHD5) from Lahendong geothermal system were selected for stable isotope analyses. Oxygen, hydrogen and carbon isotopes were analysed on quartz, clay and calcite. δ18OVSMOW of quartz is 10.32, 2.78 and 11.51 permil. Calcite δ18OVPDB ranges from -20.30 to -15.76 permil, with δ13CVPDB from -3.33 to -0.8 permil. Clay (mainly chlorite) have a δ18OVSMOW = 6.1 permil and δDVSMOW = -74.9 permil. Assuming temperature of precipitation between 250 degrees C and 270 degrees C, fluid in equilibrium with hydrothermal minerals can be recalculated. Oxygen value of the fluid that precipitated quartz, calcite and clay is generally enriched in oxygen, with isotopic value around 3 permil for pure quartz, 4.8 permil for clay and between 2 and 7 permil for calcite. The range of δ18Ofluid points to a mixed origin between depleted meteoric, neutral chloride thermal water, and magmatic oxygen. Based on these preliminary results, it is challenging to differentiate between a direct magmatic input with a high δ18Ofluid, or a low water-rock interaction where δ18Ofluid is derived from isotopic exchange with 18O-enriched magmatic rocks. The value of δ13CCO2 in isotopic equilibrium with calcite is relatively light with δ13CCO2 varying between -2.03 and 0.47 permil. Such CO2 values are above the assumed isotopic value of magmatic-derived CO2 and indicate that the carbon in the system is also influenced by calcite from near-by marine sediments. (author). 11 refs., 1 fig., 4 tabs.
[en] Petrology is used in the various stages of exploration, development and exploitation of a geothermal area, often in conjunction with other fields of study. It is an effective operations tool for predicting syn- and post-drilling conditions in a well, for field and well maintenance, and to a small extent for monitoring fluids passing through the pipelines and steam turbines. Petrological data and interpretations are important in assessing an exploration area, and in formulating and developing strategy of a geothermal field. (auth.). 11 figs
[en] Tattapani hot springs are located near the Kotli District of Azad Kashmir, Pakistan. This study evaluates these hot springs based on surface geological information, radon emission measurements, hydro-geochemical and isotopic signatures and potential source mechanisms. Field observations reveal that the hot springs are located at the crest of the Tattapani anticline along the faulted contact of Cambrian carbonates with Paleocene siliciclastics. In addition, remnants of igneous intrusions in the Cambrian carbonates are commonly observed. Spatial distribution of radon emissions (ranging between 2.1 and 29.5KBq m-3) indicates an anomalous zone located over the Cambrian-Paleocene faulted contact. Hydro-geochemical data show sodium-bicarbonate affinity of hot springs. The highest surface temperature of these springs is recorded at 60.8ºC. Average reservoir temperatures based on silica and cation geo-thermometers are 101ºC and 115ºC, respectively. Giggenbach ternary diagram (Na-K-Mg) suggests a non-equilibrium state between fluid and rock, whereas isotopic and chemical data indicate heat loss by conductive cooling and mixing with groundwater during the flow of thermal water up to the surface. Oxygen and deuterium isotopes indicate that thermal water is of meteoric origin, rain and/or snow in the north at higher altitudes providing the potential recharge. Furthermore, absence of tritium in the thermal water suggests a residence time of more than 50 years.
[en] The reservoir features of importance in the operation of enhanced geothermal systems are described first (Section 2). The report then reviews existing reservoir simulators developed for application to HDR reservoirs (Section 3), hydrothermal systems (Section 4), and nuclear waste isolation (Section 5), highlighting capabilities relevant to the evaluation and assessment of EGS. The report focuses on simulators that include some representation of flow in fractures, only mentioning other simulators, such as general-purpose programs or groundwater models (Section 6). Following these detailed descriptions, the report summarizes and comments on the simulators (Section 7), and recommends a course of action for further development (Section 8). The references are included in Section 9. Appendix A contains contractual information, including a description of the original and revised scope of work for this study. Appendix B presents comments on the draft report from DOE reviewer(s) and the replies of the authors to those comments. [DJE-2005]
[en] Working under the grant with AmeriCulture, Inc., and its team of geothermal experts, assembled a plan to apply enhanced geothermal systems (EGS) techniques to increase both the temperature and flow rate of the geothermal waters on its leasehold. AmeriCulture operates a commercial aquaculture facility that will benefit from the larger quantities of thermal energy and low cost electric power that EGS technology can provide. The project brought together a team of specialists that, as a group, provided the full range of expertise required to successfully develop and implement the project