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Study on reservoir classification and influencing factors of sandstone reservoirs

An oil field reservoir belongs to a large river-delta sedimentary system in the northern part of the Songliao Basin. The depositional environment of the reservoir has changed significantly in different periods, and the nature of the reservoir is segmented in the vertical direction, so that different types of oil layers are developed in different areas and sections. There are many sandstone layers, and the oil-bearing well section is more than 500 meters long, consisting of mutual layers of sandstone and mudstone, in which the thickness of single sand layer is only a few meters to less than 1 meter, with obvious multi-rotation nature. With the continuous development of the oil field, the oil field has entered the late stage of high water content development, and the comprehensive water content of the oil field has reached over 90%, making it more difficult to stabilize the production of the oil field. In order to further extend the stable production period of the field and achieve the goal of “oil stabilization and water control”, while doing a good job of efficient development of the main oil reservoir, the development of non-main oil reservoirs with poor pore permeability, fragmented distribution, complex reservoir properties and serious non-homogeneity is increased, and various development methods such as water drive, poly drive and ternary composite drive are used comprehensively. As the difference of reservoir properties determines the difference of oil recovery methods and oil recovery costs, for the convenience of oilfield decision making and management, oil reservoirs are divided into main and non-main reservoirs, usually the reservoir with good physical properties, high oil saturation, low oil recovery costs and high development benefits are called main reservoirs, also known as class I oil reservoirs, and other reservoirs are called non-main reservoirs.