Progress in research on the geothermal resources in Taxkorgan Valley, Xinjiang

Geothermal geological condition of Xinjiang Taxkorgan Valley was summarized in this paper. The geological structures, geothermal distribution, chemical and isotopic characteristics of geothermal fluid were analyzed. The author also investigated the geothermal formation mechanism, and calculated the geothermal resources and exploitable quantity. The results show that the geothermal resources in the study area are controlled by faults, and the ground temperature changes are obviously consistent with those of caprock, intact bedrock and fault zone (geothermal reservoir). The maximum temperature of measured thermal reservoir is 161 ℃ now, and the calculated temperature of deep geothermal reservoir can reach 222~268 ℃. Besides, the maximum geothermal gradient is 149.20 ℃/100 m. The geothermal fluid is characterized by deep circulation, which is obviously different from shallow water in hydrochemistry and isotopic characteristics. Geothermal fluid is derived from meteoric water and is stored, transported and enriched in fractures and fissures. With the heat supply of radioactive heat and crystallization heat of intrusive rock, the underground fluid continuously exchanges heat and substance with the wall rock. In the wall rock and cover layer of thermal reservoir, heat exchange is mainly in the mode of conduction, and in the heat storage reservoir,heat is mainly in the mode of convection. The stored heat in the geothermal field is 55.919×10¹¹ MJ, and the exploitable quantity of geothermal fluid is 12 593 m³/d, with the heat energy productivity of 77.9 MW. The thermal reservoir of Taxkorgan Valley has shallow buried depth and is easy to be exploited, which has considerable direct and indirect economic value.