靖边地区长6段致密砂岩储层孔隙结构及影响因素

文中综合恒速压汞与高压压汞技术,并结合常规物性分析、铸体薄片、扫描电镜等实验结果,对鄂尔多斯盆地靖边地区长6段储层孔隙结构进行了定量表征。依据压汞参数将孔隙结构分为3类,并分析了各类孔隙结构的影响因素。在恒速压汞基础上,引入分形理论探讨各类储层分形特征。结果表明:长6段储层岩石类型为长石砂岩和岩屑长石砂岩;孔隙类型以残余粒间孔为主;喉道类型主要为缩颈型喉道以及片状或弯片状喉道,孔喉半径分布在0.003~600.000μm,其中以半径小于2μm的孔喉为主;3类孔隙结构在孔隙类型、沉积环境及成岩作用方面各有差异,Ⅰ类孔隙结构储层质量最好;分流河道中砂岩具有较好的喉道分形特征,分流河道细砂岩次之,堤岸粉砂岩最差。

Pore structure and influencing factors of Chang 6 tight sandstone reservoir in Jingbian area

Quantitative characterization of the pore structure of Chang 6 reservoir in Jingbian area of Ordos Basin was performed through the constant velocity mercury intrusion,high pressure mercury intrusion technology,conventional physical property analysis,casting thin section,and scanning electron microscope.According to the mercury intrusion parameters,the pore structure was divided into three categories,and the influencing factors of various pore structures were analyzed.On the basis of constant velocity mercury intrusion,the fractal theory was introduced to explore the fractal characteristics of various reservoirs.The results show that the rock types of the Chang 6 reservoir are feldspar sandstone and lithic feldspar sandstone.The pore type is dominated by residual intergranular pores,and the throat type is mainly the neck-shaped throat,sheet or curved throat.The pore throat radius is distributed from 0.003 to 600.000μm,and it is mainly less than 2μm.The three types of pore structures differ in pore type,sedimentary environment,and diagenesis,and the type I pore structure reservoir quality is the best.The sandstone in the distributary channel has better fractal characteristics of throat,followed by the fine sandstone of the distributary channel,and the siltstone of the embankment is the worst.