Study on the Impact of Heat Extraction from Heterogeneous Geothermal Reservoirs Based on THMC Multi-field Coupled Simulation

Targeting the challenges of uneven reservoir utilization and low heat extraction efficiency in the development of heterogeneous shallow geo-thermal resources, this study aims to enhance resource utilization efficiency through optimized extraction strategies. The research scope encompasses the analysis of thermophysical heterogeneity in non-homogeneous formations, dynamic regulation of extraction patterns, and validation of efficiency enhancement mechanisms. Based on a three-dimensional numerical model of heterogeneous geothermal reservoirs, integrated with THMC (Thermo-Hydro-Mechanical-Chemical) multi-physics coupling simulations and field experiments, the impacts of permeability and thermal capacity heterogeneity on heat recovery efficiency were systematically analyzed. A “layered-phased” injection-production optimization scheme was proposed through parametric sensitivity analysis, supplemented by dynamic flow regulation technology and iterative parameter adjustments using real-time monitoring data. The results demonstrate that localized low-permeability zones in heterogeneous reservoirs lead to delayed thermal breakthrough, with conventional uniform extraction methods causing significant thermal energy loss. The optimized strategy achieved enhanced heat extraction efficiency, reduced energy consumption, and extended thermal break-through time through differentiated injection-production intensities and temporal sequencing. Key findings include: 1) differentiated injection-production intensity measures should be implemented when the permeability variation coefficient is below 0.5; 2) stepwise injection-production temperature differentials are essential in regions dominated by thermal capacity disparities. The conclusions confirm that dynamic equilibrium utilization technology effectively mitigates the negative impacts of reservoir heterogeneity, providing theoretical foundations for the sustainable development of shallow geothermal resources.