低透气性软煤层瓦斯抽采钻孔封孔参数的确定

Determination of Borehole Sealing Parameters for Gas Drainage in Low Permeability Soft Coal Seam

针对顺层平行钻孔抽采瓦斯,因煤层透气性差、钻孔煤体裂隙发育严重,导致封孔难度大、抽采瓦斯浓度低等问题,以霍尔辛赫3#煤层实际赋存条件为背景,运用数值模拟分析钻孔围岩塑性区和弹性区变形破坏区间,通过理论计算软煤层最优封孔参数范围。研究表明,钻孔塑性区为0.15~0.25 m,弹性区为0.25~0.5 m,封孔深度控制在8~16 m,压裂深度控制在0.25~0.5 m,注浆压力控制在1.3~1.5 MPa,注浆量控制在0.25~0.4 m3,为增加钻孔致密性,提升瓦斯抽采浓度提供理论支撑。

For the in-seam gas drainage in parallel drilling borehole,due to the poor permeability of the coal seam and the serious development of the cracks in the drilled coal body,it is difficult to seal the hole and the concentration of the drained gas is low.Taking No.3 coal seam of Huoerxinhe mine as the research background,the numerical simulation is used to analyze the deformation and failure zone of the plastic and elastic surrounding rock,and the optimal sealing parameter range of the soft coal seam is theoretically calculated.Research shows that the plastic zone of the borehole is 0.15~0.25 m,the elastic zone is 0.25~0.5 m,the sealing depth is controlled at 8~16 m,the fracturing depth is controlled at 0.25~0.5 m,and the grouting pressure is controlled at 1.3~1.5 MPa with the materials consumption of 0.25~0.4 m3,which provides theoretical support for concentration increasing of the borehole gas drainage.