The Koshelevsky Volcanic Block as a Prospective Site for the Development of Geothermal Power Industry on the South of Kamchatka

Abstract

The Koshelevsky Hydrothermal-Magmatic System (complex volcanic block) was formed through evolution of a large outer magmatic chamber formed at the junction of the largest South-Kamchatka fault zones. The System is composed of seven volcanic structures of Lower Quaternary to Holocene age and of basic to acid rocks. In general, this system is a complex long-lived andesite volcano formed at the boundary of two huge blocks of the Earth’s crust – the South-Kamchatka and North-Kuril segments of the Kuril-Kamchatka island arc. These huge blocks are divided by crust-cutting faults penetrated by a deep-earth (containing mantle components) metal-carrying fluid. The crust-penetrating character of faults is confirmed by gravimetric and seismologic, isotope-geochemical survey data as well as data demonstrating the existence of ascending fluxes of hydrocarbons including the heavy ones (C5H12, C6H14, C7H12, et al.).
The forecast resources of the Nizhne(Lower)-Koshelevsky geothermal field explored in 1975-1984 are estimated to yield 210 kg/sеc of dry steam. Drilling to a depth of 1,500 meters proved the existence of a thick overheated steam reservoir the lowest boundary of which was not reached. This circumstance places this field among such large-scale vapor-dominated systems as the Geysers (USA), Larderello (Italy), Matsukawa (Japan) and Kamojang (Indonesia). On the surface, steam reservoir is manifested by a compact thermal anomaly sized 250 х 500 meters with a capacity of 25,000 kcal/sec. Capacity of the second largest thermal anomaly, Verkhne(Upper)-Koshelevsky is estimated 50,000 kcal/sec. Our findings confirm the availability of large steam reservoirs in the central part (in the inner caldera) and in separate geological blocks at the border of the Koshelevsky volcanic block and reveal a deep-earth origin of a convective heat flow. All this testifies to the earlier appraisal which stated the availability of geothermal resources on site feasible enough to construct power stations with a total capacity of more than 300 МWe.