沙河子组致密砂砾岩成岩相及孔隙演化分析

通过岩芯、砂岩薄片、扫描电镜和物性、X衍射等综合分析,系统剖析徐家围子断陷沙河子组致密砂砾岩储层成岩相特征及成因.结果 表明,沙河子组发育泥质杂基充填相、长石岩屑溶蚀相、石英次生加大相、绿泥石环边胶结相和碳酸盐胶结相等5种成岩相;由沉积作用形成的碎屑矿物组分、结构差异决定了各成岩相初始孔隙度,各成岩相中成岩作用类型和强...

Diagenetic Facies and Porosity Evolution of Tight Sandstone in Shahezi Formation

In order to make clear the characteristic and genesis of tight sandstone diagenetic facies in Shahezi Formation, the core, thin-section, SEM, physical properties and X-ray analysis have been combined and systematically studied in Xujiaweizi Fault Depression. The result is that there are five kinds of diagenetic facies such as muddy-filling diagenetic facies, feldspar-debris dissolution diagenetic facies, quartz overgrowth diagenetic facies, chlorite cementation diagenetic facies and carbon cementation diagenetic facies. The difference of mineral constituent and texture between different diagenesis facies which is controlled by sedimentation is the origin of porosity evolution, the type of main diagenesis and its intensity determine the porosity evolution path in different diagenetic facies and result in spatial differentiation of properties in macroscopic and pore structure in microscopic. Even though diagenesis destroy a lot of primary pore in feldspar-debris dissolution diagenetic facies in braided delta front and chlorite cementation diagenetic facies in fan delta front, they still retain a high property before gas injection in stage B of middle diagenesis phase, which make them a favorable reservoir for gas accumulation. The reservoir in muddy-filling diagenetic facies, carbon cementation diagenetic facies and quartz overgrowth have loss most of primary pore and complete the densification process before organic matters get matured, which make it difficult for gas injection and accumulation.