突出煤层深孔水力致裂驱赶与浅孔抽采消突技术

Methane driving effect exists in hydraulic fracturing of methane-bearing coal seams. Based on the function of transforming structure, improving permeability, and driving methane of hydraulic fracturing, technology of removing outburst by hydraulic fracturing driving in deep hole and methane extraction in shallow hole of outburst coal seam is proposed and put into effect. Theory and field tests proved that the idea, "deep-hole hydraulic fracturing + methane driving + shallow-drilling-hole drainage", achieved by the construction of regional outburst preventing drilling-hole and the combination of hydraulic fracturing drilling-hole with methane extracting drilling-hole at the heading face is an effective way to eliminate the regional outburst of the heading face. By means of optimizing drilling-hole arrangement of hydraulic fracturing, alternating pressure relief hole and observation hole, reasonably determining deep hole sealing position and short hole sealing length, the safety of hydraulic fracturing driving in leading deep hole of heading face of outburst coal seam is guaranteed. Under the effect of pore water pressure caused by hydraulic fracturing and methane driving, immediately drilling a hole after hydraulic fracturing is very hard. After a period of time, it becomes very easy and the phenomena of drill sucking, drilling-hole spurting and coal booming seldom appear. As experience proves, the technology realizes the dynamic integration of permeability increasing, weakening, methane driving, extraction and water injection humidification, effectively improves methane extraction efficiency and eliminates outburst danger. Entry driving in outburst coal seam for Xuehu colliery saves work amount and time of 10 regional holes, and reduces time of methane extraction. This paper provides new ideas and technical approaches for removing outburst from outburst coal seam, especially from single, low permeability coal seams.