基于裂缝尖端应力强度因子的裂缝穿层行为分析  

Analysis of Crack Across-layer Extension Behavior Based on Stress Intensity Factor at Crack Tip

作　　者：李浩哲 姜在炳 范耀 LI Haozhe;JIANG Zaibing;FAN Yao(Research and Development Center for Resources Exploration and Development and Gas Prevention Technologies,Xi'an Research Institute of China Coal Technology & Engineering Group Co.,Xi'an 710077,Shaanxi,China;China Coal Research Institute,Beijing 100013,China)

机构地区：[1]中煤科工集团西安研究院资源勘探开发与瓦斯防治技术研发中心,陕西西安710077 [2]煤炭科学研究总院,北京100013

出　　处：《西安石油大学学报（自然科学版）》2019年第1期76-82,126,共8页Journal of Xi’an Shiyou University（Natural Science Edition）

基　　金："十三五"国家科技重大专项"煤矿区煤层气抽采利用关键技术与装备"(2016ZX05045002);中煤科工集团西安研究院有限公司科技创新基金项目(2017XAYMS18;2018XAYMS06)

摘　　要：基于裂缝尖端应力强度因子理论,采用理论分析结合数值模拟的方法,分析了裂缝尖端应力强度因子在裂缝穿层过程中的变化规律,研究了界面两侧岩石力学性质差异对地层界面处裂缝穿层扩展行为的影响。研究表明:当裂缝由硬岩层进入软岩层时,界面强度系数大于1,I型应力强度因子随着裂缝尖端与界面距离的减小迅速增大,裂缝可沿原路径穿层扩展;当裂缝由软岩层进入硬岩层时,界面强度系数小于1,I型应力强度因子随着裂缝尖端与界面距离的减小逐渐减小,裂缝的穿层扩展趋势受到限制,裂缝可能停止扩展或拐折穿层扩展。Based on the theory of stress intensity factor(SIF)at the crack tip,the variation law of SIF at the crack tip in the process of crack across-layer extension was analyzed by theoretical analysis and numerical simulation,and the influence of the mechanical property difference of rockson both sides of the interface on crack across-layer propagation behavior was studied.The results show that:when the fracture enters soft rock from hard rock,the interfacial strength factor is greater than 1,the type I stress intensity factor increases rapidly with the decrease of the distance between the crack tip and the interface,and the fracture can propagate through the interface along original path.When the fracture enters hard rock from soft rock,the interfacial strength factor is less than 1,and the type I stress intensity factor decreases gradually with the decrease of the distance between the crack tip and the interface.In this case,crack may stop propagation or change propagation direction at the interface.

关 键 词：穿层压裂 应力强度因子 裂缝穿层行为 界面强度系数 

分 类 号：TE35[石油与天然气工程—油气田开发工程]