Three-dimensional geothermal reservoir model using the magnetotelluric method in medium and deep strata of Yishu fault zone, Rizhao Section

The Yishu fault zone in Shandong Province, China, exhibits favorable conditions for medium- and high-temperature geothermal storage. However, its geothermal occurrence patterns and heat storage model remain unclear. Recognizing the importance of deep heat sources and heat channels in unraveling the formation mechanisms of medium- and high-temperature geothermal systems, we conducted a magnetotelluric survey along the Yishu fault zone, which contained 10 survey lines and 119 usable points. Using two-dimensional and three-dimensional nonlinear conjugate gradient inversion, the deep electrical structure was obtained, and the three-dimensional geothermal reservoir model in the study area was constructed for the first time. The results show that the deep low-resistance anomaly in the Yishu fault zone moves upward through the channel with slightly higher resistivity, forming a relatively low-resistance layer and a low-resistance layer in the shallow part, corresponding to the heat source, thermal conduction fault, heat reservoir, and overburden layer, respectively. The fault structure primarily controls regional geothermal anomalies, influencing atmospheric precipitation, surface water infiltration, and geothermal water migration pathways. The results of this study have a certain guiding significance for the study of the formation mechanism and distribution law of geothermal resources in the middle and deep strata of the Yishu fault zone. Additionally, the results provide valuable insights for the exploration and assessment of geothermal resources in the area.