Abstract: 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 Y anchang 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 largescale reservoirs. They should be considered as targets for futher petroleum exploration.

Key words: Ordos basin, Jing'an oilfield, Upper Triassic, sedimentary facies, delta deposit