As shallow coal resources become increasingly depleted, coal mining is extending to greater depths, making mine thermal hazards an increasingly prominent issue. This paper proposes a novel system for synergistic geothermal energy extraction from deep coal mine aquifers and coal seam cooling, aimed at achieving integrated geothermal exploitation and mine thermal hazard control. Based on a high-temperature mine in the Yuanyanghu Mining Area of Ningxia, a dual-stage, single-branch three-dimensional numerical model was established to simulate the effects of water injection pressure, water injection temperature, and level spacing on the system’s cooling performance and geothermal energy extraction efficiency. The results indicate that increasing injection pressure enhances early-stage geothermal energy extraction capacity and coal seam cooling rate, but the heat extraction power declines over long-term operation as the produced water temperature approaches the injection temperature. Lowering injection temperature significantly improves water–rock heat exchange efficiency, accelerates coal seam cooling, and increases geothermal energy extraction. Increasing level spacing helps improve geothermal energy extraction power but weakens the direct cooling effect on the coal seam. Considering the influence patterns of each parameter, the optimal combination was determined as water injection pressure of 10 MPa, water injection temperature of 10 °C, and level spacing of 80 m, which delivers the best overall performance by enabling rapid coal seam cooling and sustained geothermal energy extraction, with a cumulative geothermal output reaching 129.45 MW after 10 years of operation. This study provides a theoretical basis and technical reference for the integrated management of thermal hazards and geothermal resource development in deep coal mines.

Rapid economic growth has directly driven up energy demand, and the gradual depletion of traditional fossil fuels has severely hindered sustainable development. Developing green and efficient geothermal exploitation technologies constitutes a crucial measure for tackling this sustainable development issue. This paper presents a field test associated with a clean energy system conducted in the Guanzhong Basin, China, with the core component of a coaxial casing deep geothermal well. A distributed temperature sensing system (DTS system) with over 3000 m-depth optical fiber installed and adopted to monitor near-wellbore formation temperature changes. Combining information on the inlet/outlet water temperature and flow rate monitored by an integrated temperature–pressure monitoring system, the heat transfer patterns during the operation of the deep geothermal well are deeply investigated. The research results demonstrate that a higher operation parameter of flow rates has a significant increasing effect on the heat transfer capacity of heat exchangers for coaxial casing deep geothermal wells. Although the increase in inlet temperature has minimal effect on the outlet temperature, it leads to a continuous decline in heat transfer capacity. In addition, as heat exchange duration extends, the geothermal gradient of the near-wellbore formation progressively declines.