修武盆地下寒武统荷塘组海相页岩单轴应力作用下的各向异性研究  

Experimental Study on Anisotropy of the Lower Cambrian Hetang Formation Marine Shale Under Uniaxial Stress in Xiuwu Basin

作　　者：王一婷 杨爽[1,2,3,4] 石常亮 王安东 WANG Yi-ting;YANG Shuang;SHI Chang-liang;WANG An-dong(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;College of Earth Science,East China University of Technology,Nanchang 330013,China;Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;Key Laboratory of Petroleum Resources Research,Lanzhou 730000,China;No.6 Geological Brigade of Jiangxi Geological Bureau,Nanchang 330201,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]东华理工大学地球科学学院,江西南昌330013 [3]中国科学院西北生态环境资源研究院,甘肃兰州730000 [4]甘肃省油气资源研究重点实验室,甘肃兰州730000 [5]江西省地质局第六地质大队,江西南昌330201

出　　处：《东华理工大学学报（自然科学版）》2022年第5期443-451,共9页Journal of East China University of Technology(Natural Science)

基　　金：甘肃省油气资源研究重点实验室基金项目(SZDKFJJ20201201);江西省自然科学基金项目(2021BAB213008);江西省教育厅科技项目(GJJ180393);东华理工大学博士启动基金项目(DHBK2018030)。

摘　　要：为研究页岩的力学特征及各向异性,选取江西省修武盆地下寒武统荷塘组海相富有机质页岩为研究对象,通过单轴应力模拟、X射线衍射(XRD)、扫描电镜(SEM)及宏观裂缝观察等分析方法,对不同层理面夹角(β)的页岩微观结构、力学参数及破坏模式等各向异性进行分析。结果表明,页岩单轴抗压强度和弹性模量分别为83~200 MPa和13.40~51.35 GPa,均随层理倾角的增加而降低。最大轴向变形和泊松比分别为0.005~1.753 mm和0.01~0.38,两者均随层理倾角的增加而增加。不同层理面夹角(β)导致页岩单轴应力具有不同的破坏形式:当β为0°时,对应的破坏模式为沿层理面的拉张破坏;当β为60°时,对应的破坏模式为沿层理面的拉张破坏和剪切拉张破坏;当β为90°时,对应的破坏模式为沿层理面的拉张破裂及剪切拉张转换破裂。不同层理面页岩的脆性矿物指数为43%~66%,与泊松比和弹性模量的相关系数分别为0.5和0.6,表明脆性指数对页岩的力学参数具有一定影响作用。本研究可为修武盆地的页岩气的勘探开发提供根据和参考。In order to study the mechanical characteristics and anisotropy,the Lower Cambrian Hetang Formation marine organic-rich shale in the Xiuwu basin of Jiangxi province was selected as a research object.Through the uniaxial stress simulation experiment,X-ray diffraction(XRD),scanning electron microscope(SEM)observation and macroscopic fracture observation statistics,the microstructure,mechanical parameters and failure mode of shale with different bedding planes(β)were analyzed.The results show that the shale samples in the Hetang Formation are anisotropic in the Xiuwu basin.The uniaxial compressive strength and elastic modulus are 83~200 MPa and 13.40~51.35 GPa,respectively,which decrease with the increase ofβ.The maximum axial deformation and Poisson′s ratio are 0.005~1.753 mm and 0.01~0.38,respectively,which increase with the increase ofβ.Different bedding angles lead to different fracture modes of shale under uniaxial stress.The corresponding failure modes are tensile failure along the bedding plane withβof 0°,tensile and shear-tensile fracture withβof 60°and tensile,shear-tensile transition fracture withβof 90°.The correlation coefficients of brittle mineral index(43%~66%)with Poisson′s ratio and elastic modulus for shales with different bedding planes are 0.5 and 0.6,respectively,which indicates that the brittle index has a certain effect on mechanical parameters.This study can provide a basis and reference for shale gas exploration and development in the Xiuwu basin.

关 键 词：海相页岩 各向异性 破坏模式 荷塘组 修武盆地 

分 类 号：P554[天文地球—构造地质学]