Sedimentary characteristics and favourable area selection of tight sand-stone gas reservoirs in the Sanjianfang Formation of the Shengbei Depres-sion,Tuha Basin
Sedimentary characteristics and favourable area selection of tight sand-stone gas reservoirs in the Sanjianfang Formation of the Shengbei Depres-sion,Tuha Basin
[Objective]The Shengbei Depression is the largest petroliferous depression of the Tuha Basin.With the strong demand for the exploration and development of tight sandstone gas in the Middle Jurassic Sanjianfang For-mation,it is urgent to study the sedimentary characteristics and predict favourable exploration zones of the Sanjian-fang Formation.[Methods]Using core,well logging,and seismic data,the high-resolution sequences and sedi-mentary characteristics of the tight sandstone gas reservoir in the Sanjianfang Formation of the Shengbei Depression were studied.A lacustrine delta system was identified,and favourable exploration zones of tight gas reservoirs were predicted.[Results]Three long-term sequences(L1,L2,L3)and five medium-term sequences(M1,M2,M3,M4,M5)were developed in the Sanjianfang Formation in the Shengbei Depression;particularly,these medium-term sequences can be regionally identified.The deposition of the M1 to M3 sequences involved a braided river del-ta in the lake,but the deposition of the M4-M5 sequences involved a meandering river delta in the lake.The fa-vourable tight gas reservoirs of the Sanjianfang Formation in the Shengbei Depression were mainly developed in sub-facies of the delta front.On the plane,the Shengbei 5 and Shengshen 3 well areas of the M2 sequence,the Sheng-bei 5 and Shengbei 6 well areas of the M3 sequence,and the Shengbei 5,Shengbei 6,and Shengtan 1 well areas of the M5 sequence are favorable exploration areas.The favorable reservoir rarely appears in the M4 sequence.[Conclusion]This research can promote the exploration of tight gas reservoirs in the Sanjianfang Formation of the Shengbei Depression in the Tuha Basin.
维普
万方数据