页岩规则齿形结构面水化损伤及剪切特性研究  

Hydration Damage and Shear Characteristics of Regular Toothed Structural Planes of Shale

作　　者：景宇翔 郭印同 冯代英[2,3] 万洋辉 郑贺斌 JING Yuxiang;GUO Yintong;FENG Daiying;WAN Yanghui;ZHENG Hebin(School of Civil Engineering and Geomatics,Southwest Petroleum University,Chengdu,Sichuan,610500,China;National Key Laboratory of Geomechanics and Geotechnical Engineering(Institute of Rock and Soil Mechanics,Chinese Academy of Sciences),Wuhan,Hubei,430071,China;University of Chinese Academy of Sciences,Beijing,100049,China;School of Resources and Environmental Engineering,Wuhan University of Technology,Wuhan,Hubei,430070,China)

机构地区：[1]西南石油大学土木工程与测绘学院,四川成都610500 [2]岩土力学与工程安全全国重点实验室(中国科学院武汉岩土力学研究所),湖北武汉430071 [3]中国科学院大学,北京100049 [4]武汉理工大学资源与环境工程学院,湖北武汉430070

出　　处：《石油钻探技术》2025年第2期76-87,共12页Petroleum Drilling Techniques

基　　金：国家自然科学基金项目“复杂环境下水泥环全生命周期密封理论与控制方法”(编号:U22B6003)资助。

摘　　要：页岩储层压裂改造后,地层滑移使套管变形频繁出现,严重影响施工与生产。为了解页岩储层结构面水化损伤及水化前后的剪切特性,采用川南龙马溪组页岩试样,预制了10°和40°的2种规则齿形结构面,模拟了不同粗糙度的断层特征,并在四级法向应力下进行了水化直剪试验。试验结果表明:1)40°高起伏角度结构面在水化后表现出塑性变形特征,剪切位移−剪应力曲线呈阶梯式上升,剪切刚度下降约16.3%;而10°低起伏角度结构面则以摩擦滑移为主,剪切刚度波动较小;高法向应力(≥5 MPa)会加剧水化对结构面的破坏作用,但长时间(≥24 h)水化会使破坏促进作用趋于上限。2)在水化初期(1~2 h),40°高起伏角度结构面抗剪强度平均降低了13.05%,最终整体降低了18.19%,黏聚力与内摩擦角分别降低了16.31%和16.57%;10°低起伏角度结构面的抗剪强度参数受水化影响较小,波动范围小于5%。3)10°低起伏角度结构面在水化360 h后出现微孔洞连通和矿物分层现象,而40°高起伏角度结构面则形成大尺寸张拉裂缝,表面粗糙度增大,这是因为高角度结构面的黏土矿物分布更集中,水化软化效应更显著,导致脆性降低和塑性增强。研究结果可为页岩储层压裂设计与套管防护提供理论依据。Formation slip makes casing failure occur frequently after the fracturing of shale reservoirs,which seriously affects construction and production.In order to understand the damage caused by the hydration of shale reservoirs’structural planes and shear characteristics before and after hydration,shale samples of Longmaxi Formation in southern Sichuan were adopted.Two kinds of regular toothed structural planes of 10°and 40°were prefabricated,and the fault characteristics at different roughness were simulated.Moreover,direct shear tests for hydration were carried out under four normal stresses.The results show that:1)The structural plane with a high undulating angle of 40°shows plastic deformation characteristics after hydration.The shear displacement-shear stress curve shows the characteristics of stepped rise,and shear stiffness decreases by about 16.3%.However,the structural plane with a low undulating angle of 10°mainly exhibits frictional slip,and the shear stiffness fluctuates slightly.High normal stress(≥5 MPa)will aggravate the damage effect of hydration on the structural plane,but the damage promotion effect tends to the upper limit after a long time of hydration(≥24 h).2)At the initial stage of hydration(1-2 h),the shear strength of the structural plane with a high undulating angle of 40°decreases by 13.05%on average,and the overall shear strength decreases by 18.19%;the cohesion and internal friction angle decrease by 16.31%and 16.57%,respectively.In contrast,the shear strength parameters of the structural plane with a low undulating angle of 10°are less affected by hydration,and the fluctuation range is less than 5%.3)After 360 h of hydration,microporous connectivity and mineral stratification appear on the structural plane with a low undulating angle of 10°,while the structural plane with a high undulating angle of 40°forms large-size tensile fractures,and surface roughness increases.This difference is due to the more concentrated distribution of clay minerals and the more significant hydra

关 键 词：页岩 齿形结构面 水化作用 岩石力学 微观结构 

分 类 号：TE21[石油与天然气工程—油气井工程]