Temperature field and assessment methodology for a low-medium temperature geothermal field: 3D geological-geophysical modeling in the Xiong'an Area, Northern China

Mid-low temperature hydrothermal systems are widely distributed in continental intraplate basins, and accurately characterizing their deep thermal structures is crucial for understanding regional geothermal genesis. As a typical intraplate field, the Xiong'an Area in North China possesses significant deep potential. However, previous studies focused on localized assessments of isolated shallow fields, lacking regional 3D simulations based on fine structural constraints, which restricts the understanding of deep heat transfer mechanisms.In this study, we integrated three deep seismic reflection profiles, one magnetotelluric (MT) profile, regional geological, and well-log data to construct a high-resolution 3D geological-geophysical model. Constrained by petrophysical data, we employed a Multi-source data integration approach to solve the 3D steady-state heat conduction equation, achieving high-precision geothermal simulation down to 5 km depth, validated by measured well temperatures.Our results reveal significant spatial differentiation in the regional thermal structure, primarily controlled by varying "caprock-reservoir" configurations. The northern region (e.g., Rongcheng and Niutuozhen fields) exhibits a "thin caprock-shallow reservoir" pattern (< 3 km), whereas the southern region (e.g., Gaoyang field) features a "thick caprock-deep reservoir" pattern (> 3 km). The 3D model indicates the southern deep system possesses a significantly higher geothermal gradient, forming a promising target for deep exploration. Furthermore, we identify a concealed deep geothermal prospect near the Raoyang depression. This study delineates reliable exploration targets and provides a universally applicable framework for modeling Multi-source data integration in intraplate geothermal systems.