Sedimentary characteristics and model of proximal shallow water delta in the Eocene upper Es3s5 unit of Bamianhe Oilfield

Shallow water delta has become a key object in the field of oil and gas geology. Further Understanding of its sedimentary model and sand body distribution is of great significance to accelerate the oil and gas exploration and development of this kind of reservoir. The sedimentary characteristics of shallow water delta in such a proximal shallow delta system were studied and the regional characteristic sedimentary model was established for the upper Es3s5 sand unit of the Eocene Shahejie Formation in Bamianhe Oilfield by integrating the geological data from borehole, logging and chemical analysis. Results show that, under the tectono-structural background, the ancient material source, paleoclimate and other factors, the upper Es3s5 sand unit was formed and composed of mainly fine sandstone, and the sand body size increased gradually from bottom to top, showing progradation characteristics as a whole. The sedimentary microfacies such as underwater distributary channel, underwater natural levee sheet sand and so on were mainly developed. The estuary bar was merely developed, and the underwater distributary channel was distributed in an intertwined and contiguous manner, and a large area of sand sheet was formed in the shallow water area.