Relationship between sandstone architecture and remaining oil distribution pattern: A case of the Kumkol South oilfield in South Turgay Basin, Kazakstan

Taking the Kumkol South oilfield in South Turgay Basin, Kazakstan as an example, this article summarizes the controlling pattern of different types of sandstone architecture on remaining oil distribution through examining architecture characteristics, development effect and remaining oil distribution characteristics of meandering river sandstone, braided river sandstone and delta sandstone. The braided river sandstone has simple architecture which is extensive connecting body with horizontal mud-interlayers. The water flooding sweeps evenly and the edge-bottom water drives quickly in braid river sandstone. And the remaining oil distribution pattern of braid river sandstone is the vertical blocking pattern controlled by the horizontal mud-interlayers at the high water cut stage. The meandering river sandstone is a half connecting body with abandoned channels and the lateral accretion mud-interlayers, so the injected water sweeps through the middle and lower parts of point bar sandstone, and its remaining oil distribution pattern is the horizontal blocking pattern controlled by abandoned channels and the lateral accretion mud-interlayers. The delta sandstone has a complex architecture of mosaic structure with abundant horizontal and vertical mud-interlayers and mud-interbeds, in which the injected water sweeps along preferential path, with low sweeping efficiency, and the remaining oil distribution pattern is the complex blocking pattern controlled by horizontal and vertical mud-interlayers and mud-interbeds. The results show that different techniques should be used to enhance the remaining oil recovery because of the different remaining oil distribution patterns in different kind of sand bodies.