Formation and distribution of reservoir of Member 1 of Shahejie Formation, Wennan Oilfield

The Wennan Oilfield is located at the south central uplift belt, Dongpu Sag, where the reservoir of Member 1 of Shahejie Formation is the major super-seder and it is a lithologic and lithologic-fault block. The reservoir in Member 1 of Shahejie Formation developed between source rock and halite, forming inter-bed combination of self-generate, self-storage and self-cover. The oil is mainly immature because that the most source rock of Member 1 of Shahejie Formation entered the oil-window. The sedimentary facies of Member 1 of Shahejie Formation in the Wennan Oilfield is controlled by successive sub-aqueous palaeo-uplift and the source in the SW direction, and a delta-beach-bar system was developed. Sand pinched out to palaeo-heights and the transition from sand to carbonate and halite is gradual. The reservoir of Member 1 of Shahejie Formation in the Wennan Oilfield is obviously different from those of Member 2 and 3 of Shahejie Formation, which are the major reservoirs in the whole Zhongyuan Oilfield.