煤矿井下水平钻孔压裂裂缝起裂特征研究  

Fracture initiation characteristics of horizontal drilling fracturing in underground coal mine

作　　者：赵凯凯 朱凯雄 冯彦军 孙晓冬 郑仰发 王鹏 王宇 ZHAO Kaikai;ZHU Kaixiong;FENG Yanjun;SUN Xiaodong;ZHENG Yangfa;WANG Peng;WANG Yu(National Key Laboratory of Intelligent Coal Mining and Rock Stratum Control,Beijing 100013,China;CCTEG Coal Mining Research Institute,Beijing 100013,China;Tiandi Science and Technology Co.,Ltd.,Beijing 100013,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;China University of Mining and Technology-Beijing,Beijing 100083,China)

机构地区：[1]煤炭智能开采与岩层控制全国重点实验室,北京100013 [2]中煤科工开采研究院有限公司,北京100013 [3]天地科技股份有限公司,北京100013 [4]中国科学院地质与地球物理研究所,北京100029 [5]中国矿业大学(北京),北京100083

出　　处：《煤炭工程》2025年第3期134-142,共9页Coal Engineering

基　　金：国家重点研发计划项目(2022YFC3004604);国家自然科学基金项目(52404129,52304141)。

摘　　要：为了厘清煤矿井下水平钻孔压裂裂缝的复杂起裂行为,以煤矿井下地应力回归公式、钻孔孔壁应力分布以及最大拉应力准则为基础,构建了煤矿井下水平孔压裂裂缝起裂的理论计算模型,进而对地层埋深和钻孔方位对裂缝起裂特征参数的影响规律进行了研究。同时采用三维离散格子数值模拟方法,对水平钻孔压裂裂缝的起裂动态演化过程进行了模拟。结果表明:水平孔压裂裂缝的起裂压力会受到地层埋深与钻孔方位角的共同作用。起裂压力与地层埋深呈正相关关系,当埋深从150 m增加到1100 m时,起裂压力峰值的增幅约为46.47 MPa。在埋深小于1100 m的情况下,起裂压力随钻孔方位角的增加呈现先增大后减小的趋势。起裂参数突变点所对应的钻孔方位角会随埋深的增加而单调递减,在突变点附近,起裂压力达到峰值,并且起裂位置从90°突变为0°。裂缝的方向角由约0°突增至某一正值,随后呈现出类似抛物线的变化特征,在埋深1100 m以内,裂缝方向角均小于27.08°。钻孔压裂裂缝起裂演化过程表现为微破裂点的萌生、孔壁破裂线的发育以及宏观裂缝椭圆形的自相似扩展等多个阶段的演化过程。研究结论能够为煤矿井下水力压裂水平钻孔的布置方案优化提供参考和借鉴。To clarify the characteristics of fracture initiation in horizontal drilling in coal mine,a theoretical calculation model was established based on the regression equation of in-situ stress,the stress distribution of borehole wall and the maximum tensile stress criterion,and the influence of the depth and orientation of borehole on fracture initiation parameters were studied.The 3D discrete lattice numerical method was used to simulate the evolution of fracture initiation in horizontal drilling fracturing.The results show that the fracture initiation pressure is influenced by the buried depth of formation and the azimuth of borehole.The fracture pressure is positively correlated with the buried depth.When buried depth increases from 150 m to 1100 m,and the peak fracture pressure increases by 46.47 MPa.When the buried depth is less than 1100 m,the fracture initiation pressure increases first and then decreases with the increase of the drilling azimuth.The borehole azimuth corresponding to the abrupt point of fracture initiation parameter decreases monotonically with the increase of burial depth.The crack initiation pressure reaches its peak near the mutation point,and the crack initiation positions all changes from 90° to 0°.The fracture direction angle suddenly increases from about 0° to a certain positive value,and then presents a parabolic change characteristic,and the fracture direction angle is less than 27.08° within 1100 m buried depth.The fracture initiation of borehole fracturing is a multi-stage evolution process,including the stages of micro-fracture initiation,hole wall fracture line development and macroscopic fracture elliptic self-similar expansion.The research conclusion can provide reference for the optimization design of borehole layout scheme in underground coal mine.

关 键 词：水力压裂 水平钻孔 地应力 裂缝起裂 地层埋深 

分 类 号：TD82[矿业工程—煤矿开采]