Microcosmic characteristics of fine-grained sedimentary reservoirs and its application——By taking S352 well in Anfutun area of Damintun sag as an example

The S352 well in Anfutun area of Damintun sag was comprehensively studied by using core observation, thin section identification, X-ray diffraction whole rock analysis, casting image, scanning electron microscopy, mercury injection and gas adsorption, unconventional physical property analysis and so on. The results show that the fine-grained sedimentary rocks in the fourth member of Shajiahe formation in S352 well are mainly composed of carbonate oil shale, sandwiched mudstone and argillaceous micritic cloud rocks. The reservoir space types are intercrystalline pores, dissolved pores, organic matter pores, structural fractures and rock-forming fractures, etc. The pore diameter is mostly less than 50 nm, the porosity is mainly 5.0% ～ 9.0%,and the permeability is mostly less than 1.000×10~(-3) μm ~2, which belongs to low porosity, ultra-low permeability reservoir. The dominant lithology series are successively from good to bad: carbonate-bearing oil shale, argillaceous micritic cloud rock, and cloudy mudstone. The research methods have positive reference significance for the research results of fine-grained sedimentary reservoirs and later exploration and development.