页岩各向异性力学特性微观测试方法研究  

Research on the micro-scale method for testing the mechanical anisotropy of shale

作　　者：贾锁刚 万有余[1] 王倩 刘世铎 刘又铭 王志晟 叶禹 齐春艳 JIA Suogang;WAN Youyu;WANG Qian;LIU Shiduo;LIU Youming;WANG Zhicheng;YE Yu;QI Chunyan(Petrochina Qinghai Oilfield Company,Dunhuang 736202,Gansu,China;CNPC Engineering Technology R&D Company Limited,Beijing 102206,China;Beijing Huamei Inc.CNPC,Beijing 100028,China)

机构地区：[1]中国石油青海油田公司,甘肃敦煌736202 [2]中国石油集团工程技术研究院有限公司,北京102206 [3]北京华美世纪国际技术有限公司,北京100028

出　　处：《地质力学学报》2021年第1期10-18,共9页Journal of Geomechanics

基　　金：中国石油天然气股份有限公司重大科技专项(2016E-0105)。

摘　　要：页岩力学各向异性特征是地应力、井壁稳定、水力裂缝扩展相关研究的重要基础参数。针对页岩力学各向异性宏观测试中存在样品制取困难、制样成功率低的特点,采用来源丰富的钻井岩屑或破碎岩块,通过研究纳米压痕实验原理、实验方法和数据解释方法,采用连续刚度测试方法对平行层理和垂直层理的页岩试样进行纳米压痕测试;基于硬度的分类准则将纳米压痕数据分为三类主要矿物基质进行合理解释,采用接触刚度法计算硬度、杨氏模量,采用能量法计算断裂韧性,得出了页岩粘土基质的杨氏模量、硬度和断裂韧性。测试结果表明这种基于硬度的分类准则处理纳米压痕数据是方便合理的。页岩粘土基质力学特性在纳米尺度上具有各向异性,纳米尺度力学参数与层理方向相关。页岩不同力学参数的各向异性表现不同,杨氏模量各向异性较弱,断裂韧性各向异性较强。平行层理方向断裂韧性为垂直层理方向断裂韧性的80%。The mechanical anisotropy of shale is an important basic parameter for the study of in-situ stress,sidewall stability and hydraulic fracture propagation.In view of the limitations and low success rate for sample preparation in macro-scale tests,we chose clastic rocks and fragmentized blocks which were easily found as the subjects for micro-scale tests,and used continuous stiffness measurements to carry out the nano-indentation tests on the shale samples with horizontal bedding and vertical bedding.The test data were analyzed on three main mineral matrices which were identified by the classification rule of hardness.And the hardness and young’s modulus of the shale clay matrix were calculated by contact stiffness measurements and the fracture toughness by energy method.The test results proved the reasonability and convenience of the classification rule of hardness in processing nanoindentation data.Shale clay matrix is anisotropic at the nano-scale while the mechanical parameters at the nanoscale are related to the bedding direction.The anisotropy of each mechanical parameter varies in intensity.The anisotropy of young’s modulus is weak,while that of fracture toughness is strong.The fracture toughness with horizontal bedding is 80%of that with vertical bedding.

关 键 词：页岩 力学特性 各向异性 纳米压痕 硬度 杨氏模量 断裂韧性 

分 类 号：TE142[石油与天然气工程—油气勘探]