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采用铸体薄片、共聚焦扫描电镜成像技术、常规压汞分析和恒速压汞分析等多种手段,对三肇凹陷扶余油层中—低渗透储层孔隙结构特征进行综合研究。结果表明,储层孔隙结构异常复杂,粒内溶孔、粒间溶孔等次生溶蚀孔隙构成了其主要储集空间,孔径大小在22.49~49.31 mm之间,孔喉连通性差异较大。在此基础上,以渗透率为主线,结合孔隙类型、孔喉半径、孔喉半径比以及孔喉连通性等参数,将研究区储层主要划分为中渗透储层和低渗透储层2种基本类型,前者以中渗透中孔细喉道型为主,后者又进一步细分为低渗透中孔细喉道型、低渗透小孔不均匀微细喉道型和低渗透小孔较均匀微细喉道型等3个亚类。明确储层微观孔隙结构特征及其分类,有利于进一步开展储层评价,对油田后期挖潜具有重要的指导意义。
The porous structure of medium and low permeability reservoirs in Fuyu oil layer of Sanzhao depression was comprehensively studied by means of casting sheet, confocal scanning electron microscopy, conventional mercury intrusion analysis and constant pressure mercury intrusion analysis. The results show that the pore structure of the reservoir is extremely complicated. Secondary dissolution pores such as intragranular dissolution pores and intergranular dissolution pores constitute the main reservoir space. The pore size ranges from 22.49 to 49.31 mm, and the pore-throat connectivity is quite different. On this basis, taking the permeability as the main line and combining the parameters of pore type, pore throat radius, pore throat radius ratio and pore-throat connectivity and other parameters, the reservoirs in the study area are mainly divided into two types: medium permeability reservoir and low permeability reservoir The former is dominated by medium-permeability thin-throated mesopores, the latter is further subdivided into low-permeability mesoporous thin throat-shaped, low-permeability microporous heterogeneous fine throat-shaped and low-permeable micropores are more uniform and fine Throat type 3 sub-categories. Clearly defining the microscopic pore structure of the reservoir and its classification will be conducive to further reservoir evaluation and have important guiding significance for tapping the potential of the oilfield in the late stage.