Influence of mid-term base level cycle changes on the development characteristics of shallow water delta sand bodies: A case study of the Fuyu oil layer in the Mu 17 block in the southern Songliao Basin

The Fuyu oil layer in the southern Songliao Basin is a shallow-water delta sedimentary system. Frequent changes in the base level lead to obvious differences in the superimposed style, scale and geometry of the sand bodies, which seriously affects the distribution of remaining oil. Taking the Fuyu oil layer in the Mu 17 block in the southern Songliao Basin as an example, using a large number of cores and logging data in the dense well pattern development area, based on the relationship between the accommodated space (A) and the sediment supply (S), it is clear that The Fuyu oil layer develops the superimposed styles of cut-stack, superimposed and isolated sand bodies. In the depositional period of MSC1 and MSC2, the superimposed style of the cut-and-stacked sand body was the main one; in the depositional period of MSC3, the superimposed style of the superimposed sand body was dominant; in the depositional period of MSC4, the sand body was the least developed, and the superimposed style of the isolated sand body was the main one.This study has important guiding significance for clarifying the influence of medium-term base level cycle changes on the superposition law of shallow water delta sand bodies