Sedimentary features of the Dongying Formation in Chengdao area and their geological significance

The exploration focus in the Dongying Formation of Chengdao area,the Bohai Bay Basin is stratigraphic-lithologic reservoirs,to which the key is a correct understanding of deposition characteristics of reservoir sandbody.A comprehensive analysis of core,drilling/logging,and seismic data of the area,confirms the existence of sedimentary systems such as deeper lake-turbidite fan,fan delta-slump turbidite fan,braided delta,low-sinuosity stream-flood plain,and etc,and provides insights into the composition and features of these sedimentary facies.The results indicate that palaeogeomorphic characteristics before the deposition of the Dongying Formation show a strong controlling effect upon the deposition of the lower Dongying Formation.Based on sedimentary facies analysis within the sequence stratigraphic framework,the paper discusses the spatial distribution of these sedimentary facies and the petroleum geologic significances of the study on sedimentary features in such aspects as the types and distribution of reservoir sandbody,favorable strata,characteristics of spatial distribution,and so on.