[en] The background on the general scenario of energy resource development in the country is described. Highlights of the exploration history of the Tongonan and Palinpinon geothermal fields in the Philippines are then presented. This is discussed in conjunction with the strategies and policies taken in the development of each field. Finally, the common policies and contrasting development strategies are compared and evaluated. The conclusion derived is that the development strategy decisions at Tongonan are influenced by the regional power demand, topography, and the large extent of the resource. In contrast, the development at Palinpinon is less constrained by the external influence of regional power needs, but, instead, is significantly dominated by the limitations imposed by the rugged terrain and the physical characteristics of the resource area. Such comparison demonstrates the site-specific nature of geothermal development. (auth.). 8 figs.; 2 refs

[en] A method was developed to enhance geothermal steam production from two-phase wells at THE Geysers Geothermal Field. The beneficial result was increased geothermal production that was easily and economically delivered to the power plant

[en] At Brady Hot Springs, a geothermal field in Nevada, heated fluids have been extracted, cooled, and re-injected to produce electrical power since 1992. Analysis of daily pumping records and catalogs of microseismicity between 2010 and 2015 indicates a statistically significant correlation between days when the daily volume of production was at or above its long-term average rate and days when no seismic event was detected. Conversely, shutdowns in pumping for plant maintenance correlate with increased microseismicity. Our hypothesis is that the effective stress in the subsurface has adapted to the long-term normal operations (deep extraction) at the site. Under this hypothesis, extraction of fluids inhibits fault slip by increasing the effective stress on faults; in contrast, brief pumping cessations represent times when effective stress is decreased below its long-term average, increasing the likelihood of microseismicity.

[en] It is obvious that GPP is the kind of projects, which may be very attractive in certain regions but may seems difficult and risky on the first look and if not properly developed. Specially in the regions and countries where are missing references for such kind of projects this project may be 'pioneer' type and from the beginning will for sure request lot of ambitions and patience from site of developer and project owners and lot of confidence from administration and official governmental bodies and or banks and investors. From this reason there is most important for successful development to appoint very professional partners in development and to split the project to the logical development stages each describing the specific futures and targets for individual stages. (authors)

[en] Complete text of publication follows. Self-potential (SP) survey was carried out over trails at Akita-Yakeyama volcano in 2007. It was reported that a wide-area SP observation was carried out by Kikuchi et al. (1987) in the Sengan geothermal area in 1983 and 1985. In addition, the SP surveys from 1993 to 1998 were performed in the vicinity of the Sumikawa power plant by Matsushima et al. (2000). The observation result in this study reproduced almost the same SP distribution of the result of 1983 around the summit area including summit crater and Kunimidai. On the contrary, large decrease of SP more than 650mV compared with 1983 was recognized in the vicinity of the Sumikawa power plant. It is the largest potential change found in this field. Comparing the result of this study with that of 1996, the decrease of SP about 300mV was also seen. It is clear that the decrease of SP is influenced by the Sumikawa power plant whose operation began in 1995. An explanation of the mechanism of the SP decrease at the power plant was considered by Matsushima et al. (2000). In addition, moderate SP decreases of 150mV or more at the surroundings of the Beko moor field and the Goshogake hot spring were recognized compared with 1983. The Beko moor field is next to the Sumikawa power plant to the south and the Goshogake hot spring is aligned to the south of it. It might be suggested the influence of the operation of the power plant extends to these surrounding areas.

[en] This article examines the effects of competition of geothermal energy production with other technologies. The topics of the article include near-term market growth, cause for cautious optimism, limits to development of geothermal energy production, economic arguments for development of geothermal power plants, the effects of a competitive market on industry survival

[en] Based on information of enthalpies of the fluids of wells from the geothermal reservoir of Los Humeros, Puebla, Mexico, we determined the thermodynamic conditions of the reservoir comparing the values of enthalpies of the fluids of discharge of the wells with the values published in the literature for different thermodynamic state of fluids.

[en] Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions

[en] Waters discharged at Tokaanu-Waihi have the highest Cl (3500 mg/kg) and B (100 mg/kg) contents of the Taupo Volcanic Zone. Very high B contents in waters and steam at Ketetahi suggest a possible link. Relative Na-K-Mg and Ca contents of Tokaanu, produces highly immature, steam-heated, essentially NH₄-SO₄ waters. The isotopic composition of Tokaanu waters is compatible with derivation from both Ketetahi and Hipaua, another area of intense fumarolic activity some 3 km to the W. At Ketetahi, the inferred B contents of deep waters, however, are much too high, while those at Hipaua are suitable to act as source waters for Tokaanu. Relative CO₂, H ₂S, CH₄ contents, and higher hydrocarbons in Tokaanu and Hipaua vapors are very similar, but differ consistently from those of the Tongariro discharges. The close relation between Tokaanu and Hipaua is strongly supported by the isotopic compositions of CO₂,CH₄ and He. All three areas, Ketetahi, including Red and Central Crater, Tokaanu-Waihi, and Hipaua appear to be associated with arc-type, probably andesitic magmatism. (author). 22 refs., 6 figs., 3 tabs

[en] In this study, we determined the main direction of geoelectric strike in the southern part of the Wayang Windu geothermal field using magnetotellurics (MT) data. The strike direction was obtained by analyzing data using impedance polar and Zstrike rose diagram. We investigated 51 MT data at different sites of the southern part of the Wayang Windu geothermal field. Determination of geoelectric strike direction is important since the strike is the rotation references in MT data processing. Our findings had pointed out that the geoelectric strike direction in this study area is in accordance with the direction of geological structure and has a good correlation with structures delineated from 3D MT inversion model. (paper)