岩土力学2024，Vol.45Issue(1)：59-67,9.DOI:10.16285/j.rsm.2023.0106
CO2-水作用对层状页岩拉伸破坏影响的微观损伤研究
Effect of microscopic damage on tensile failure of laminated shale after CO2-H2O treatment
摘要
Abstract
CO2-H2O can damage the rock microstructure and change the tensile failure characteristics and fracture propagation mode during CO2 fracturing in shale reservoirs.X-ray diffraction(XRD)tests,scanning electron microscope(SEM)observation,and Brazilian tests are conducted to investigate the microscopic damage and failure characteristics,and fracture propagation mode of Longmaxi and Chang-7 shale specimens after CO2-H2O treatment.The results show that the microscopic damage of bedding after CO2-H2O treatment is more significant than that of the matrix.The volume of bedding clay minerals is reduced due to dehydration,the organic matter is extracted and contracted,and the large-size microfractures(10-30 pm in length and 1-5 pm in width)are generated in the laminae distributed along the bedding.Carbonate and feldspar minerals in the matrix are dissolved and induce randomly distributed small-size microcracks(＜1 pm in length and＜0.5 pm in width).After CO2-H2O treatment,the tensile strength of shale decreases,and the anisotropy increases.The failure mode of shale changes from tensile failure to mixed tension-shear failure,and the shear action of specimens loaded vertically to the bedding is stronger.Fracture propagation is restricted by the bedding for specimens loaded vertically to the bedding,leading to fracture propagation along the bedding;for specimens loaded horizontally to the bedding,the bedding exerts stronger constraints on fracture propagation,resulting in fracture propagation merely within the bedding.关键词
CO2-水作用/页岩/拉伸破坏/层理/数字图像相关Key words
CO2-H2O treatment/shale/tensile failure/bedding/digital image correlation分类
建筑与水利引用本文复制引用
杜布戈,张广清,周大伟,屈乐,邱仁怡,范宗洋..CO2-水作用对层状页岩拉伸破坏影响的微观损伤研究[J].岩土力学,2024,45(1):59-67,9.基金项目
国家自然科学基金(No.51925405,No.52104050,No.52004223).This work was supported by the National Natural Science Foundation of China(51925405,52104050,52004223). （No.51925405,No.52104050,No.52004223）
