深层页岩巴西劈裂破坏力学行为数值模拟研究  

A Numerical Simulation for Damage Mechanical Behavior of Brazilian Splitting Test of Deep Shales

作　　者：崔壮 侯冰[1,2,3] CUI Zhuang;HOU Bing(State Key Laboratory of Petroleum Resources and Engineering(China University of Petroleum(Beijing)),Beijing,102249,China;MOE Key Laboratory of Petroleum Engineering(China University of Petroleum(Beijing)),Beijing,102249,China;Department of Petroleum Engineering,China University of Petroleum-Beijing at Karamay,Karamay,Xinjiang,834000,China)

机构地区：[1]油气资源与工程全国重点实验室(中国石油大学(北京)),北京102249 [2]石油工程教育部重点实验室(中国石油大学(北京)),北京102249 [3]中国石油大学(北京)克拉玛依校区石油学院,新疆克拉玛依834000

出　　处：《石油钻探技术》2024年第2期218-228,共11页Petroleum Drilling Techniques

基　　金：国家重点研究发展计划项目“深部含煤岩系超临界CO_(2)穿层压裂-驱替-封存评价技术研究”(编号:2022YFE0129800)资助。

摘　　要：为揭示页岩纹理特征与破坏强度之间的作用机理,利用黏聚力单元法建立了巴西劈裂三维数值模型,研究了纹理角度和纹理强度对页岩破坏模式和抗拉强度的影响,并利用声发射分布特征精确分析了裂纹演化过程。研究结果表明:巴西劈裂数值模拟结果与试验结果基本一致,利用黏聚力单元法可以准则预测页岩破坏行为;纹理角度和纹理强度耦合作用下页岩试样破坏模式分为6种;中心破坏的页岩试样,声发射能量–位移曲线以单峰值分布型为主,拉伸剪切复合破坏的页岩试样,声发射能量–位移曲线以多峰值分布型为主;页岩试样抗拉强度各向异性显著,相同纹理角度下,纹理强度越高,主裂纹越接近加载直径方向,试样抗拉强度越大。研究结果进一步揭示了深层页岩破坏机制,为页岩储层压裂设计提供了理论依据。In order to investigate the mechanism between shale texture characteristics and tensile strength,a threedimensional Brazilian splitting test numerical model was established by the cohesive element method.The effects of texture angle and strength on damage modes and tensile strength were studied,and the crack growth behavior was accurately analyzed using acoustic emission distribution characteristics.The results indicate that the numerical simulation outcomes of the Brazilian splitting test were basically in accordance with the experimental results.The cohesive element method can be used to predict the shale’s damage behavior.The damage modes of shale specimens are classified into six categories under the coupling of texture angle and strength.For shale specimens with central damage,the acoustic emission(AE)energy-displacement curves are dominated by a single-peak distribution type.For shale specimens with tension-shear mixed damage,the AE energy-displacement curves are dominated by a multiple-peak distribution type.The tensile strength of shale specimens is significantly anisotropic.As the texture strength increases,and the primary crack approaches the loading diameter direction,the tensile strength of the specimens gets higher under the same texture angle.The results of the study also reveal the damage mechanisms in deep shales and provide theoretical basis for the fracturing design for shale reservoirs.

关 键 词：深层页岩 巴西劈裂 数值模拟 破坏模式 抗拉强度 

分 类 号：TE311.2[石油与天然气工程—油气田开发工程]