Sedimentary systems in the third member of the Shahejie Formation, Yong-8 region, Dongying depression

The sequence stratigraphic division and sedimentary facies analysis of the third member of the Shahejie Formation in the Yong-8 region, Dongying depression are based on the core examination, well logs, seismic and palaeontological data. The third member of the Shahejie Formation is divided into three long-term cycles and two sedimentary facies types, including the delta and bathyal-abyssal facies. The main controlling factors of sedimentary facies comprise tectonic settings, palaeogeomorphical features and provenances. Vertically, the third member of the Shahejie Formation exhibits the evolutionary sequences of the prodelta, delta front, delta plain, river and shallow lake subfacies, representing the lake, river and lake sedimentary systems. Laterally, the river and delta facies are developed gradually from the east to the west of the study area. The results of research for the sedimentary systems may facilitate the reservoir assessment and hydrocarbon exploration in the study area.