Thermodynamics‐Based THMC Model for Solute Transport in Sorptive Fractured Rock: Coupling Multi‐Phase Flow, Heat, and Deformation

Abstract Fractured porous rocks host a complex interplay of heat, fluids, deformation, and chemical reactions, yet their combined influence on solute transport remains poorly resolved. Here we show that these processes are more tightly coupled than previously assumed. We develop a thermodynamics‐based thermo‐hydro‐mechanical‐chemical (THMC) framework that embeds non‐isothermal sorptive coupled deformation and dynamic porosity evolution directly into dual‐porosity transport equations, revealing previously hidden linkages between pressure, temperature, stress, and solute concentration. The model reproduces analytical benchmarks and laboratory measurements, giving confidence in its predictive capability. When applied to a shale‐gas reservoir, the coupled formulation exposes systematic biases—up to 2%–9% in solute distribution—arising when gas adsorption, porosity feedback, or thermal stresses are omitted. Our results demonstrate that THMC coupling is not a secondary refinement but a first‐order control on contaminant transport, with implications for fractured reservoirs across energy, environmental, and subsurface engineering applications.