Distribution of remaining oil based on a single sand body analysis: a case study of Xingbei Oilfield

Abstract The description of a single sand body for remaining oil predictions is critical to the enhancement of oil recovery of an old oilfield. Taking the fluvial facies of the Xingbei Oilfield as an example, a single sand body can be divided into four categories—“tabulated reservoir”, “untabulated reservoir”, “single channel sand body” and “abandoned channel”—using the reservoir architecture analysis method. The boundary surface of each type may be mud barriers or only an erosion surface, which was traced by careful anatomization of the single sand body. Then, a fine single sand body reservoir geological model was constructed using a combination of a determined modelling method and stochastic modelling method. The numerical simulation is executed using the constructed geological model to forecast the remaining oil distribution quantitatively. The results show that the remaining oil was distributed in the bottom parts of the abandoned channel, top part of the point bar, tabulated reservoir, and channel edges. The movements of the injection water were mainly controlled by the mud barrier and superimposed styles of single sand body, which determines the formation of the remaining oil. This research has important guidance for oilfield development in the late stage, whose reservoir is composed of single sand bodies.