Research on the Effectiveness of Gas Control in Low-Permeability Coal Seams Based on Microbial Gas Dissolution

To shorten the gas control period in low-permeability coal seams, the effectiveness of microbial gas dissolution technology for gas control was investigated through a combination of field tests and numerical simulations. First, three groups of injection boreholes were constructed, and the microbial gas-dissolving solution was injected into the coal seam, followed by an evaluation of the treatment effect after three days. Furthermore, based on a multiphysics-coupled modeling framework, the conventional borehole drainage process was simulated using the Partial Differential Equation (PDE) module of COMSOL Multiphysics to compare the evolution of coal seam gas pressure under conventional drainage with the field performance of the gas dissolution treatment. The results showed that the injected bioactive solution promoted methane oxidation and rapidly reduced the gas content and pressure in the treated region. After 3 days of gas dissolution treatment, the average gas content and gas pressure within the overlapping influence zones between the injection borehole groups decreased by 38.0% and 80.7%, respectively, relative to their initial values. However, the treatment effect gradually weakened with increasing distance from the injection zone, indicating spatial attenuation of the effective influence of the bioactive solution in the low-permeability coal seam. Comparatively, conventional drainage required approximately 68 days to reduce the gas pressure to the same level achieved by the gas dissolution treatment within 3 days, demonstrating that gas dissolution technology can drastically accelerate the gas control cycle. Nevertheless, further large-scale application requires consideration of economic feasibility and continued optimization of injection parameters and field implementation procedures.