摘要
为了探究渗透压-应力耦合作用下页岩的渗透性,选用岩石伺服三轴试验系统,在不同渗透压差和围压条件下对页岩进行全应力、应变渗透性试验。分析页岩不同变形阶段与渗透率的关系,探讨页岩破坏过程中形成的局部压缩带与渗透性的关联性。试验结果表明:相同渗透压差、不同围压下,初始渗透率随着围压增大而呈不同程度的减小,峰值强度随着围压增加而增大;相同围压、不同渗透压差下,试样渗透率随着渗透压差增加而呈不同程度的增大,但是峰值强度有一定程度的降低;试验结果表明,页岩出现了局部压缩带的现象,压缩带的出现对渗透率增加有着抑制的作用,它的出现并不是页岩脆-延转换临界点出现的特征,而是孔裂隙萌生、扩展并开始软化的标志性特征;页岩试样在高围压条件下出现硬化现象,在低围压条件下的页岩试样内部孔裂隙渗流网络的形成早于高围压下硬化的页岩试样,破坏模式以高角度剪切破坏为主。研究页岩不同应力环境下的渗透性,对揭示页岩气开发过程中页岩的渗流机制具有实际意义。
To understand the permeability of shale under osmotic pressure and stress coupling, a servo-controlled triaxial rock testing system was employed to determine the complete strain-stress curves and permeability of shale under different confining pressures and osmotic pressures. The relationships between the deformation stage and permeability of shale samples were analyzed. The relationship between the compression zone and the permeability in the process of shale destruction was discussed. The results show that under different confining pressures, the initial permeability decreases with the increase of confining pressure, and the peak intensity increases with the increase of confining pressure. Under the same confining pressure, the permeability of the samples increases with the increase of the osmotic pressure, but the peak strength decreases to a certain extent. It is found that there is a localised compression zone in the shale, and the compression zone appears to inhibit the increase of permeability. The appearance of the compression zone is not the characteristic of the brittle to the ductile transition critical point, but the characteristics of the initiation, propagation and softening of pores. The shale samples appear hardening under high confining pressure. Under the low confining pressure, the formation of the fracture network in the shale is earlier than the samples under high confining pressure, and the failure mode is mainly dominated by the high-angle shear failure. This study on the permeability of shale under different stress conditions is significant to reveal the percolation mechanism of the process of shale gas development.
作者
左宇军
孙文吉斌
邬忠虎
许云飞
ZUOYu-jun;SUNWen-ji-bin;WUZhong-hu;XUYun-fei(Mining College,Guizhou University,Guiyang,Guizhou 550025,China;Guizhou Key Laboratory of Comprehensive Utilization of Nonmetallic Mineral Resources,Guizhou University,Guiyang,Guizhou 550025,China;Engineering Laboratory for Efficient Utilization of Superior Mineral Resources in Guizhou Province,Guizhou University,Guiyang,Guizhou 550025,China;Engineering Center for Safe Mining Technology under Complex Geologic Condition,Guizhou University Guiyang,Guizhou 550025,China;College of Civil Engineering,Guizhou University,Guiyang,Guizhou 550025,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2018年第9期3253-3260,共8页
Rock and Soil Mechanics
基金
国家自然科学基金重点项目(No.51574093
No.51774101)
贵州省重大应用基础研究项目(黔科合JZ字[2014]2005)
贵州省高层次创新型人才培养项目(黔科合人才(2016)4011号)
贵州大学人才引进项目(贵大人基合字[2017]63号)~~
关键词
岩石力学
页岩
渗透压-应力耦合
渗透性
压缩带
rock mechanics
shale
osmotic pressure and stress coupling
permeability
compression zone
