利用铸体薄片、扫描电镜、恒速压汞、核磁共振、真实砂岩微观驱替实验等测试手段,对安塞油田长6特低渗透储层微观孔隙结构、可动流体饱和度特征进行了研究.结果表明:粒间孔对可动流体饱和度具有较大的贡献,溶蚀孔不利于可动流体的赋存,喉道大小、孔喉比、分选系数对可动流体饱和度影响大,而储层物性、面孔率、孔隙半径的影响微乎其微.利用真实砂岩微观驱替型实验得到:不同物性样品的驱替类型及驱油效率存在明显差异 渗透率大于1.0×10-3 μm-2的样品,孔隙类型为溶孔-粒间孔型,驱替类型为网状-均匀驱替,最终驱油效率为69.3％;渗透率0.5× 10-3～1.0×10-3 μm2的样品,孔隙类型为粒间孔-溶孔型,驱替类型为指状-网状驱替,最终驱油效率为43.8％;渗透率小于0.5×10-3 μm2的样品,孔隙类型为微孔-溶孔型,驱替类型为指状驱替,最终驱油效率为32.9％.%In this paper,microscopic pore structure and movable fluid saturation characteristics of Chang 6 ultra-low permeability reservoir in Ansai Oilfield are studied by means of casting thin slices,scanning electron microscopy,constant pressure mercury intrusion,nuclear magnetic resonance,and real sandstone microscopic model.The results show that the content of intergranular pores has a good contribution to the saturation of the movable fluid,while the content of the dissolved pores is unfavorable to the occurrence of the movable fluid;throat size,pore throat ratio,sorting coefficient have a great influence on mobile fluid saturation,otherwise reservoir physical properties,porosity,pore radius do less.Real sandstone micro-displacement experiment shows that the displacement path and oil displacement efficiency of the samples with different physical properties are obviously different.The samples with permeability greater than 1.0× 10-3 μm2 are of pores-intergranular pore type and the type of displacement is net-uniform displacement with final flooding efficiency 69.3％.The samples with permeability from 0.5×10-3 to 1.0×10-3 μm2,the type of pores are dissolved pores-intergranular pore type,the displacement type is finger-net displacement with displacement efficiency 43.8％.The samples with permeability less than 0.5 ×10-3 μm-2 have micropore-dissolution pore type and displacement type are fingerdisplacement with final displacement efficiency 32.9％.
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