Characteristics of geothermal resource in Qiabuqia, Gonghe Basin: Evidence from high precision resistivity data

Abstract

The Gonghe Basin in the Qinghai Province lies on the north-eastern margin of the Qinghai-Tibet Plateau and is rich in geothermal resources. Qiabuqia is one of the most promising places in China to establish an enhanced geothermal system and realize electricity generation from hot dry rocks. Although studies have identified the basic geological conditions of the Gonghe basin, the establishment of an enhanced geothermal system is still needed to clarify the characteristics of the rock mass and the distribution of groundwater. Thus, we developed a wide field electromagnetic method for detection of geological structure and groundwater around the target wells in Qiabuqia. The multiplicity of inversion was avoided through the direct conversion of frequency to depth, and the original data were preserved to the greatest extent. The results show that the stratum of Qiabuqia can be divided into two parts: a low-resistivity sedimentary layer and a high-resistivity granite basement; the depth of granite in the northeast is slightly shallower than that in the southwest. We can speculate that the top of the granite basement was relatively broken and the rock mass around well GH01 was more water-rich, whereas the rock masses around wells GR1 and GR2 were less water-rich. The rock mass in the northeast is shallow and more integral, with less water, which is more conducive to the hot dry rock development test.