Application of Time-Frequency Electromagnetic Technology In The Detection of Hot Dry Rock With Granite As Thermal Reservoir In Gonghe Basin

Hot dry rock is a kind of high-temperature renewable clean energy with the greatest development potential in geothermal energy, which has the characteristics of large amount of resources, no pollution and zero emission, good safety, non seasonal thermal energy continuity and high utilization rate; Granite thermal reservoir type dry-hot-rock has become a hot spot in the research and development because of its stable high-temperature heat source, high heating rate and no fluid in dense rock. The Gonghe Basin in Qinghai Province is a hot research area of hot dry rock with Granite as thermal reservoir in China, and the Qiabuqia area is one of the areas with the best development prospects at present. In order to find out the thickness of caprock and the buried depth of the top interface of granite basement in Qiabuqia area, analyze the relationship between the occurrence and integrity of granite body and the law of terrestrial heat flow conduction, and predict the spatial distribution, the time-frequency electromagnetic method is applied to the exploration of hot dry rocks in Qiabuqia area. Through high-standard data acquisition, refined data processing and resistivity-constrained inversion, resistivity horizon calibration and fracture structure interpretation are carried out by using the known borehole data, and the thickness of caprock is about 900-1400m; The buried depth of the top interface of granite is shallow in the east and deep in the west, and the shallow layer is rock bed, the middle layer is rock stock, and the deep layer is rock foundation. At the same time, the idea of hot dry rock exploration is determined, and the boundary and spatial distribution characteristics of the hot dry rock mass are predicted in combination with the borehole temperature measurement data. In the survey area, the Qiabuqia hot dry rock mass is distributed in a large area at an altitude of -1000m, and many local high points are distributed on it. The Dalianhai rock mass is relatively limited, with only one local high point.