东—韩地区延长组长2油层组储层孔隙结构特征

Characteristics of pore structure of Chang 2 oil reservoir set of Yanchang Formation in Dong-Han area

采用物性分析、薄片观察、扫描电镜、常规压汞等方法,对低渗透储层特征及孔隙结构进行了研究,并探讨了孔隙结构对低渗透储层物性的影响。结果表明:储层孔隙类型有残余粒间孔隙、溶蚀孔隙、晶间孔隙、微裂缝,以溶蚀孔隙为主要类型;喉道类型以细喉道为主;孔隙结构以中孔-细喉道型为主,其次是小孔-细喉道型、大孔-中粗喉道型;孔喉半径越大,低渗透储层的渗透性越好;分选系数和歪度系数反映了低渗透储层喉道大小不均一、类型多样及储层微观非均质性强的特点。

The property analysis, thin sections, scanning electronic microscope and mercury injection tests were applied to study the characteristics of low permeability reservoir and pore structure and discuss the effect of pore structure on physical properties of low permeability reservoir. The result shows that the pore types include residual intergranular pores, dissolved pores, intercrystalline pore and micro-fracture,dominated by dissolved pores. Fine throat is the main throat type. Pore throat structure is mainly of middle pore-thin throat, followed by eyelet-thin throat and macropore-medium throat. The greater the pore throat radius is, the better the permeability of low permeability reservoirs is. Sorting coefficient and skewness show the characteristics of low permeability reservoirs such as various types of throat, different sizes and strong microscopic heterogeneity.