Abstract： Aiming at the problem that the effective extraction radius of borehole calculated by numerical simulation method is larger than that of field measurement, the theoretical analysis method is used to study the causes of the error between numerical simulation and field measurement. Based on the analysis results, the coal seam gas migration control equation of double-hole single-permeability model is established. The numerical simulation software was used to study the distribution law of gas pressure under different model conditions. It was found that under the same extraction time, the gas pressure distribution curve calculated by the single-hole single-permeability model was located below the double-hole single-permeability model, indicating that the gas pressure of the single-hole single-permeability model at the same position from the borehole was smaller than that of the double-hole single-permeability model. The field measurement results show that the effective extraction radius of the borehole is 2.64 m, 3.46 m and 4.05 m at 30 d, 60 d and 90 d, respectively. The maximum error between the calculation results and the measured results is only 3.95 %, which is more in line with the actual results.
