Depositional Systems of Nanpu Depression and its Petroleum Potential

The facies analysis is key to understand the evolution of a depositional system. Lacustrine depositional systems were considered in this study. In this study we used core samples and well log analysis to identify different lithofacies in variety of depositional systems. Tree chronostratigraphic units have been identified: The first is composed of Cretaceous, Jurassic, Carbo-Permian and Ordovician rocks, the second is composed by Paleogene System, which is consists of Shahejie Formation (Es3, Es2 and Es1) and the Dongying Formation (Ed3, Ed2 and Ed1) and the third is Neogene System, which comprised of Guantao (Ng) and Minghuazheng (Nm) Formations. The thickness of these tree stratigraphic units was estimated to being in the range of 7500 ~ 8000 m. Nanpu Depression as part of Bohaiwan Basin, underwent an extensional faulting in the early Cenozoic time. This dynamic process led to the development of faulted lacustrine basin, which controlled the sedimentary infilling. Depositional systems and facies types were influenced by paleogeography and the geology setting. The sedimentary facies and structural background of Nanpu Sag are favorable for finding more stratigraphic and structural oil traps.