Investigating the Impact of Groundwater Flow on Subsurface Temperature Fields Based on Numerical Simulation-Taking Yuncheng Basin in Shanxi Rift as an Example

[Objective]The groundwater flow exchanges heat with surrounding rocks, altering the subsurface temperature distribution, which requires further investigation and analysis. [Methods]This study employed finite element numerical simulation to study the deep temperature characteristics beneath the Yuncheng basin within the Shanxi Rift. A typical NW-striking cross section through the Yuncheng basin was selected to explore the impact of groundwater on the deep temperature field. The subsurface temperature characteristics were analyzed by comparing two scenarios: pure heat conduction and a combined heat conduction-convection model. [Results]When both heat conduction and convection modes work, solely gravity-driven groundwater flow significantly alters the temperature distribution from pure heat conduction mode. Significant temperature variations occur in recharge and discharge areas. However, groundwater flow induced by combined gravity and buoyancy from temperature differences produces more significant change in subsurface geothermal field, especially in high-permeability deep fault zones and their vicinity. Within the Emei northern and southern faults and the Zhongtiao northern fault, both local positive and negative temperature anomalies are generated. The comparison between simulated results with the collected temperature curves from nearby geothermal boreholes indicates that heat transfer mechanism in the Yuncheng basin closely resembles a combination of heat conduction and convection. [Conclusion]This study reveals the influence and control of groundwater flow on the deep temperature distribution, providing a crucial basis for the geothermal exploration and prediction in the Shanxi Rift.