Simulation and Application of Gas Drainage Method by Double Row Borehole Drilling in Thick Coal Seam

In order to improve the efficiency of gas extraction in 3^# coal seam of Sanyuan Coal Industry. Fluent software was used to verify the correctness of the single row drilling model at first, then numerical simulation was carried out for 8 m thick coal seam with single row and double row drilling respectively.The results show that the effect radius of single row holes of gas extration is about 2.5 m and the effective radius is 1.7 m, which can only affect part of the surrounding area.After adopting double row boreholes, the gas flow field basically covers all the 8 m thick coal seam, and the gas pressure around the borehole is much less than that around the single row borehole. Through the practical application of double row drilling in 3^# coal seam with 7.83 m thick coal seam, it is found that the pre-pumping gas efficiency reaches 70%, and the effect is remarkable.Double row boreholes can improve the gas extraction rate and coverage rate of thick coal seam, effectively reduce the outburst risk of outburst coal seam, and ensure the safety of production in coal mines.