Research On Pore Structure And Seepage Characteristics Of Chang7Reservoir In Jiyuan Area

In recent years, the rapid development of economy leads more and more oil and natural gas demand, China’s energy supply and energy security outburst in the passing day. Some low permeability and extra low permeability reservoir are become favorable area for exploration and development. As to the research extent, the predecessor did a great deal work on research sedimentary facies, turbidite sedimentary evolution of chang7formation, but little on the pore structure and seepage characteristics. It is not enough of clarifies the basic geological conditions. This paper based on existing research results, analysis of the collected data, combined with experimental results, study the pore structure and flow characteristics of the chang7formation in the area, in order to provide theoretical support for the later development.The study used many modern detection technology such as SEM, Cathode luminescence, cast thin section, constant rate mercury, conventional mercury injection, X diffraction, oil-water relative permeability, combined with the microscopic sandstone model experiment of water displacing oil, made a more comprehensive study on pore structure and flow characteristics of Chang7reservoir in Jiyuan area.Chang7reservoir in Jiyuan area is mainly composed of compact reservoir and extra low porosity and extra low permeability reservoir. The lithology is mainly dark gray, grayish brown fine, fine grained lithic feldspar sandstone, containing a small amount of feldspar sandstone. To pores Types, more intergranular pores, feldspar dissolved pore and dissolved pore, few intercrystalline pore and micro cracks. There are pore narrowing throat, necking throat and flat or curved lamellar throat. In the experiment, Water displacing oil with three types of finger, mesh and uniform shape. Rresidual oil is wide distribution cluster and slabby because of circumferential motion. Experimental results show that the oil displacement efficiency model is determined by many factors together. Pore types, pore combination type, pressure, and water flooding, any one factor of them will influence residual oil forms.In summary, Chang7of low porosity and super low permeability with characteristic of more dissolution pore, poor pore connectivity, strong heterogeneous, poor filtration capacity, low final oil recovery efficiency.