厚煤层顶板定向长钻孔水力压裂瓦斯抽采工程实践

Engineering practice of gas drainage by hydraulic fracturing with long directional boreholes in thick coal seam roof

韩城矿区主采3号煤层松软,瓦斯含量高、压力大,常规抽采方式效果差,为了实现矿井突出灾害区域超前治理,开展了桑树坪二号井北轨道大巷3号煤层顶板长钻孔水力压裂抽采瓦斯技术研究。在北轨道大巷完成了1个定向长钻孔钻探(主孔长度504 m)及分段水力压裂施工(8段),泵注压力19.6~29.6 MPa,压裂液单段用量56~268 m^(3),总用量737.7 m^(3)。根据实测及现场观察得出顶板压裂孔压裂影响半径为30~40.5 m;稳定抽采期间,瓦斯抽采浓度10%~40%(平均浓度25.1%),平均抽采纯量0.6 m^(3)/min,抽采效果良好。

The main mining 3#coal seam in Hancheng mining area is soft,with high gas content and pressure,and the effect of conventional extraction method is poor.In order to realize the advanced treatment of mine outburst disaster area,the research on gas extraction technology of long borehole hydraulic fracturing in the roof of North track roadway 3#coal seam of Sangshuping No.2 well was carried out.One directional long borehole drilling(main hole length 504m)and segmented hydraulic fracturing construction(8 sections)were completed in the North track roadway.The pump injection pressure was 19.6~29.6mpa,the consumption of fracturing fluid in a single section was 56~268m^(3),and the total consumption was 737.7m^(3).According to the actual measurement and field observation,the fracturing influence radius of the top plate fracturing hole is 30~40.5m;During the stable extraction period,the gas extraction concentration is 10%~40%(average concentration is 25.1%),the average extraction purity is 0.6m^(3)/min,and the extraction effect is good.