Abstract:the working area is located at the edge of Yutai depression, which is covered with thick sedimentary strata. It provides a good cover for geothermal formation. The thermal reservoir is Ordovician Majiagou group. The buried depth of its roof exceeds 1000m, and the maximum buried depth can reach 3000m. Theoretically, it is a better geophysical method to carry out seismic exploration to find the target in this area, but the buried Cenozoic basalt about 300m to 600m below the surface has a strong shielding effect on seismic waves, resulting in weak seismic reflection information or even no seismic reflection information of the underlying strata of basalt, which seriously affects the imaging effect of the underlying strata of basalt; CSAMT method also has low resistance shielding in the coverage area of low resistance sedimentary strata, with rapid attenuation, obvious nearfield effect, and the exploration depth is no more than 1000m. Based on the preliminary inference of regional gravity field on the Jiaxiang fault, geophysical exploration method mainly based on magnetotelluric sounding (MT) and supported by conventional electrical sounding can better reduce the influence of basalt and low resistance shielding, improve the deep exploration ability, divide the boundary between geothermal caprock and thermal reservoir, delineate the heat conduction and water diversion structure, and finally drill the geothermal well of limestone thermal reservoir with the highest temperature in southwestern Shandong province.
