Место издания:Ministery of Geology of Uzbekistan Tashkent
Первая страница:75
Последняя страница:102
Аннотация:Electrical resistivity of rocks could serve as a convenient proxy parameter to be used for indirect temperature estimation from the surface electromagnetic (EM) data, which is especially useful for electromagnetic sounding of geothermal areas. The paper presents a review of recent advances in electromagnetic geothermal exploration based on using of an indirect EM geothermometer. The accuracy of the EM temperature extrapolation in depth depends on the ratio between the borehole length and the extrapolation depth. In particular, when extrapolating to a depth twice as large as the well depth the relative error is 5-6%, and if the extrapolation depth is three times as large, the error is about 20%. This opens up the opportunity to use available temperature logs for estimating the temperatures at depths 3-10 km without extra drilling. Application of the indirect EM geothermometer in three geothermal areas (Soultz-sous-Forêts, France, Hengill, Iceland, and Travale, Italy) is discussed. It is shown that practical application of indirect electromagnetic geothermometer enables constraining the locations for borehole drilling, determining the heat sources, estimating the heat transfer dominating mechanisms and type of fluids.