As a clean and renewable energy source with huge reserves, hot dry rock geothermal resources have received wide attention. The geothermal field plays a crucial role in studying the heat source mechanism of hot dry rock, defining target areas, and evaluating resources. In this study, the three-dimensional structural inversion of the Gonghe Basin is carried out using magnetotelluric sounding, and the Curie isothermal surface is obtained by analyzing regional aeromagnetic data. By coupling low-resistance and high-conductivity zones with temperature distribution and integrating the Curie isothermal surface with high-temperature anomalies of some melts, we constructed an initial temperature field model based on comprehensive geophysical data. The temperature field model of the Gonghe Basin is established by using the adaptive finite-element temperature conduction control equation and the constraints of the temperature data from geothermal wells. The temperature field model provides a basis for the future exploration of hot dry rock resources in the Gonghe area.

The formation and exploitation of geothermal reservoirs in hot dry rock (HDR) primarily rely on microseismic methods, but seismic techniques lack sufficient sensitivity to fluids. The electromagnetic method, however, demonstrates sensitivity to fluid movements during the monitoring of fracturing processes that form geothermal reservoirs in HDR. This study examines the role of electromagnetic methods in HDR development, taking China’s first Enhanced Geothermal System (EGS) demonstration site in the Qinghai Gonghe Basin as a case study. Based on the Gonghe HDR development site, a frequency-domain 3D borehole-to-surface electromagnetic forward modeling method with unstructured-grid discretization was employed to simulate the complex electromagnetic field responses induced by fracturing fluid injection and dynamic changes in fractures during HDR reservoir development. To enhance computational efficiency, a supercomputer was employed to perform 3D borehole-to-surface electromagnetic data inversion under conditions of massive multi-source and multi-frequency data. This quantitatively revealed the electrical characteristics at different depth intervals within the study area. The research demonstrates the feasibility of borehole-to-surface electromagnetic methods for determining the spatial distribution of fracturing injection, dynamically monitoring fracture development, and tracking fluid migration, thereby providing crucial technical support for monitoring HDR resources development.