Sedimentary Facies of the 8th Member of Lower Shihezi Formation in Su6 Area, Sulige Gas Field

Su6 area is the main gas-producing district in Sulige gas field. There is a lot of debate among institutes and scholars on the type and characteristic of sedimentary facies in the 8th member of the Middle Permian Lower Shihezi Formation which is the main gas-producing strata. According to comprehensive studies of well logs, cores and previous study, the authors conclude that the kind of depositional system is river in the 8th member of Lower Shihezi Formation and it could be further classified into two kinds as the braided-river in the lower part and the meandering-river in the upper part. Based on the deliberate analysis of microfacies, the authors set up the gentle-gradient braided river sedimentary model and the multi-channel and low-sinuosity meandering river sedimentary model, and think that the most favorable reservoir is overriding sand bodies of channel bar and point bar and channel bed sand bodies is sub-favorable reservoir. The establishment of the sedimentary facies type and sedimentary model gives a good method to favorable facies belts prediction, reservoir evaluation and exploitation in Sulige gas field including the whole Su6 area.