松软煤层水力压裂钻孔失稳分析及固化成孔方法  

Analysis on borehole instability and control method of poreforming of hydraulic fracturing in soft coal seam

作　　者：翟成[1,2] 李全贵[1,2] 孙臣[1,2] 倪冠华[1,2] 杨威[1,2] 

机构地区：[1]中国矿业大学安全工程学院,江苏徐州221116 [2]煤炭资源与安全开采国家重点实验室,江苏徐州221116

出　　处：《煤炭学报》2012年第9期1431-1436,共6页Journal of China Coal Society

基　　金：国家重点基础研究发展计划(973)资助项目(2011CB201205);国家自然科学基金资助项目(51274195);煤炭资源与安全开采国家重点实验室开放基金资助项目(09KF09)

摘　　要：分析了煤矿井下松软突出煤层钻孔失稳变形机理,指出巷道围岩应力和钻孔二次应力是煤层施工压裂钻孔后孔壁弱结构易产生破坏失稳、易塌孔和成孔难的主要根源。提出了一种有效的区域固化成孔方法,模拟分析了松软煤层和采用高强度材料固化后钻孔周围应力场和位移变化。结果表明:松软煤层中钻孔位移变形量和塑性区范围大,钻孔易发生失稳破坏;对封孔段采取固化成孔措施后,浆液渗透填充到煤岩体的裂隙中,起到加固、充填密实裂隙作用,增强孔壁围岩的强度,钻孔变形量和塑性区范围减小,有效防止了钻孔发生失稳破坏,提高了成孔率。Borehole instability deformation mechanism of soft coal seam in coal mine was analyzed, and stresses in roadway surrounding rock and the secondary stress of borehole as the main cause of borehole deformation instability of hydraulic fracturing in coal seam was pointed out. Proposed an effective regional curing pore-forming method, simula- ted and analyzed the borehole stress field,displacement field and change of plastic failure zone in soft coal seam and the coal seam which cured with high strength material. The results show that the area of displacement and plastic fail- ure zone is bigger while drilling in soft coal seam, and it is prone to instability and failure. Based on regional curing pore-forming method, the cracking in the soft rock surrounding borehole wall can be filled with grout, the strength of the surrounding rock can be steadily reinforced. Thus that area of displacement and plastic failure zone can be de- creased and the rate of pore-forming can be enhanced.

关 键 词：瓦斯抽采 水力压裂 钻孔失稳 固化成孔 松软煤层 

分 类 号：TD712.6[矿业工程—矿井通风与安全]