Abstract:
We investigate the impact of high-temperature thermal drive technology on coalbed methane (CBM) desorption and extraction efficiency through a combination of experiments and numerical simulations. Focusing on anthracite coal from the Qinshui Coalfield, gas desorption experiments were conducted under different temperature gradients. The results indicate that increasing the temperature significantly enhances both the rate and total volume of gas desorption. At 140 °C, the cumulative desorption volume was 226.4% higher than the baseline at 30 °C. Based on the thermo-flow-solid coupling theory, a numerical model for coal seam heat injection was developed to simulate and analyze the influence of hot water injection parameters on the temperature field, pressure field, and extraction efficiency. The study found that the injection temperature is the dominant factor, with 80 °C achieving an optimal balance between the thermal influential radius and engineering economy. The injection pressure has a limited effect on the temperature field, with 2 MPa being sufficient to meet requirements. Increasing the injection borehole diameter enhances the heat transfer area, and 105 mm was identified as the optimal choice considering both construction efficiency and extraction performance. Using the optimized parameter combination (80 °C, 105 mm, 2 MPa), the calculated cumulative gas production over 30 days of heat-injection extraction was 7.24 times that of conventional extraction. The research confirms that high-temperature hot water injection technology can effectively enhance CBM desorption and migration, providing a theoretical basis and technical pathway for the efficient management of gas in low-permeability coal seams.