复合射孔技术对松软煤层的损伤效果研究  

Research on damage effect of compound perforating technology on soft coal seam

作　　者：杨兆中[1] 王乃璐 张平[2] 李成兵[1] 李小刚[1] YANG Zhaozhong;WANG Nailu;ZHANG Ping;LI Chengbing;LI Xiaogang(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;China United Coaled Methane Co.,Ltd.,Beijing 100011,China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点试验室,四川成都610500 [2]中联煤层气有限责任公司,北京100011

出　　处：《煤炭科学技术》2022年第3期144-151,共8页Coal Science and Technology

基　　金：国家科技重大专项资助项目(2016ZX05044-004-002)。

摘　　要：松软煤层具有弹性模量低、抗压强度低及泊松比高等特点,同时节理、割理发育,存在大量天然裂缝。大量研究数据表明,水力压裂技术对煤层气的增产效果并不理想,于是国内外学者逐渐将目光转移到复合射孔技术。针对复合射孔技术对松软煤层的损伤效果问题,采用试验与数值模拟相结合的方法,选取松软煤层中煤样进行三轴压缩试验及分离式霍普金森杆试验,并进行数值模拟计算。结果表明:煤岩在静态压缩下呈现偏塑性,在高应变率条件下呈现明显的脆性,表现出很强的气动力冲击可压性;复合射孔技术比普通射孔剪切和拉伸破坏范围明显更大,损伤裂缝数量更多,裂缝扩展更长;HMX-HTPB系推进剂,升压延迟时间长,峰值压力高,对射孔孔道及井筒周围煤岩压裂作用明显,因此较适用于复合射孔;推进剂外置对射孔孔道附近的煤岩压裂改造作用较为明显,形成多条延伸距离较远的损伤裂纹,对套管、水泥环的损伤破坏效应相对弱。The soft coal seam has the characteristics of low elastic modulus,low compressive strength and high Poisson’s ratio.At the same time,joints and cleats are developed,and there are a large number of natural fractures.A large number of research data show that the stimulation effect of hydraulic fracturing technology on coal seam is not ideal,so scholars at home and abroad gradually turn their attention to compound perforation technology.In view of the damage effect of compound perforating technology on soft coal seams,a combination of experiment and numerical simulation was adopted to conduct triaxial compression test and SHPB test by using coal samples in soft coal seams,and numerical simulation calculations were also carried out.The results show that:coal and rock exhibit partial plasticity under static compression,exhibit obvious brittleness under high strain rate conditions with strong aerodynamic impact compressibility;the composite perforation technology has a significantly larger shear and tensile failure range than ordinary perforation,with more damage cracks and longer crack propagation;HMX-HTPB propellant has a long delay time for pressure rise and high peak pressure.It has obvious fracturing effect on the perforation channel and coal rock around the wellbore,so it is more suitable for composite perforation;the external propellant has a more obvious effect on coal fracturing near the perforation tunnel,forming multiple damage cracks that extend far away,and the damage and destruction effect on casing and cement ring is relatively weak.

关 键 词：复合射孔 松软煤岩 损伤效果 分离式霍普金森杆 

分 类 号：TD823[矿业工程—煤矿开采] TD745[矿业工程—矿山开采]