Sedimentary Facies of Chang-6 Member of Yanchang Formation of Upper Triassic in Jing'an Oilfield

Based on 5 profiles and 17 wells' core data, integrated with reservoir lithology, depositional structure and grain size analyses, the polycyclic sequence stratigraphic classification of Chang-6 member is made, and the isochronal formation correlation framework of different time scales is established. By analysis of the sedimentary facies in-plane through-going feature, it is recognized that Chang-6 member of Yanchang formation of Triassic in Jing'an oilfield belongs to lacustrine delta system which is dominated by delta front sub-facies. The effect of sedimentary facies on reservoir physical property is discussed. It is concluded that well developed depositional microfacies as channel mouth bar and underwater distributary channel are premium petroliferous sandbodies and provided with the geologic conditions for forming large-scale reservoirs. They should be considered as targets for further petroleum exploration.