Quantifying Formation Permeability Effects on High-Temperature Aquifer Thermal Energy Storage

High-temperature aquifer thermal energy storage (HT-ATES) has emerged as a promising technology for mitigating fluctuations in renewable energy supply, with system performance being strongly controlled by formation permeability. In this study, a three-dimensional coupled thermo-hydro-mechanical (T-H-M) model was employed to investigate the influence of mean permeability, anisotropy, and heterogeneity on doublet HT-ATES performance in aquifers. The results indicate that higher mean permeability promotes lateral energy dispersion and reduces pumping energy demand but simultaneously decreases thermal recovery. As the permeability anisotropy of the storage aquifer increases, lateral dispersion of heat is enhanced, vertical focusing is suppressed, and thermal recovery efficiency is reduced. Heterogeneity and spatial continuity intensify preferential flow, with heterogeneity having a more pronounced negative impact on recovery efficiency. Regarding conventional sandstone formations, modest temperature changes do not bring about notable modifications to the formation's porosity and permeability characteristics. Hot wells were found to be more sensitive than cold wells due to lower density and viscosity, as well as the enhanced convection of hot water. Overall, weak anisotropy and low heterogeneity were identified as optimal conditions for balancing recovery efficiency and pumping requirements, providing quantitative insights for formation selection and parameter optimization in HT-ATES system design.