High-Resolution Modeling and Sustainability Assessment of the Dongli Lake Geothermal Reservoir with Fault Zone Anisotropy

The structurally complex Cangdong fault zone primarily controls the medium-low temperature geothermal potential of the Dongli Lake field in Tianjin, China. However, the accurate numerical characterization of such fault-controlled reservoirs remains challenging, as regional models often oversimplify fault zones as equivalent porous media, obscuring critical permeability anisotropy. To address this gap, this study established a high-resolution conceptual and numerical model of the western reservoir by integrating seismic profiles, drilling data, and dynamic monitoring. The core of our approach was a meticulous natural-state calibration process, which quantitatively constrained the reservoir's properties. The calibrated model achieved an exceptional match with observed data, with mean relative errors of 3.33% for temperature and 9.73% for pressure. Crucially, this process revealed a pronounced permeability anisotropy in the primary Jixian System Wumishan Formation (Jxw) reservoir, with horizontal permeability (3.00×10⁻¹³ m²) an order of magnitude higher than its vertical component (3.00×10⁻¹⁴ m²), directly quantifying the fault zone's dominant control on fluid flow. Subsequent dynamic sensitivity analysis, grounded in this validated model, demonstrates that optimal well placement must target these high-permeability zones proximal to the main fault. Furthermore, we propose adaptive reinjection protocols to manage reservoir pressure and mitigate thermal drawdown. This research provides a robust, calibrated framework and delivers scientifically-grounded strategies to ensure the long-term sustainability of the Dongli Lake geothermal resource, with methodological implications for modeling other fault-controlled sedimentary basin systems.