吉木萨尔凹陷芦草沟组页岩储集层裂缝成因及耦合关系

Genesis and Coupling Relationship of Fractures in Shale Reservoir of Lucaogou Formation in Jimsar Sag,Junggar Basin

通过观察准噶尔盆地吉木萨尔凹陷芦草沟组页岩储集层的野外露头、岩心和薄片,结合成像测井资料,采用油气运移物理模拟实验、三轴压裂实验等方法,以岩石应力—应变曲线为依据,研究了微观尺度到宏观尺度的页岩储集层裂缝成因及耦合关系。研究结果表明,构造缝与层理缝相互耦合,可显著改善页岩储集层的物性;层理缝与构造缝形成过程中相互影响,发育层理缝的岩石受到垂直层理面的挤压时,易发生多期破裂形成层理缝与构造缝交织的裂缝系统,受到平行层理面的挤压时,会形成以层理缝为主的期次少的裂缝系统;构造缝与层理缝平行耦合对页岩储集层的渗透率无显著影响,构造缝与层理缝垂直耦合可使页岩储集层的渗透率明显升高。

According to the data of outcrops,cores and thin sections of the shale reservoir of the Lucaogou formation in the Jimsar sag,Jung⁃gar basin,and considering the imaging logging data,physical simulation of oil and gas migration and triaxial rock fracturing experiment etc.,we studied the genesis and coupling relationship of fractures in the shale reservoir in micro and macro scales based on the stress⁃strain curve.The results show that:(1)The mutual coupling of bedding fractures and structural fractures can greatly improve the physical proper⁃ties of the shale reservoir;(2)Bedding fractures and structural fractures are influenced by each other during their devlopment.When the rock with bedding fractures is compressed in the direction vertical to the bedding plane,multi⁃stage fractures are likely to appear and form a fracture system with interlaced bedding fractures and structural fractures;when the rock is compressed in the direction parallel to the bed⁃ding plane,a fracture system with less stages may occur,which is mainly composed of bedding fractures;(3)The parallel coupling of struc⁃tural fractures and bedding fractures has no significant impact on the permeability of the shale reservoir,while their vertical coupling can significantly increase the permeability of the shale reservoir.