Sedimentary facies in the second and third members of the Shahejie Formation in the Chezhen depression,Shengli Oil Field

The Chezhen depression as a fault basin is located in the northeastern part of the Bohaiwan Basin in Shandong.The upper submember of the third member and the lower submember of the second member of the Palaeogene Shahejie Formation are considered as the typical deeply faulted third-order sequences constrained by episodic faulting.These sequences may be divided into the lowstand,transgressive and highstand systems tracts.Sedimentary facies consist of fan delta,delta,nearshore submarine fan, sublacustrine fan,littoral-shallow lake beach and bar,as well as littoral-shallow lake,and semideep-deep lake facies and subfacies,of which the preferred sedimentary facies include delta,fan delta front,sublacustrine fan,midfan and outer fan of the nearshore submarine fan,and beach-bar facies developed in the littoral-shallow lake.