The Conditions Of Oil And Gas Accumulation And The Exploration Potential Of E_s1 Member In Banqiao Sag,Huanghua Depression

The proven oil and gas reservoirs in Banqiao sag is mainly concentrated in the structural belts which are in the central and southern Banqiao.With the improvement of oil and gas exploitation,the search for more resource has become the focus of exploration in the later period.During the exploration,it is found that there are subtle reservoirs of self-generated and self-storage in the depression and slope areas with low exploration degree in Banqiao sag.The oil and gas reservoirs are so difficult to explore that the conventional methods for constructing anticline reservoirs are no longer applicable.The Dazhangtuo and Banqiao oil reservoirs discovered by Es₁ in Banqiao sag are taken as research objects in this study.With the methods of the basin simulation,sedimentary characterization and reservoir prediction and the comprehensive utilization of seismic data,well-logging,mudlogging,core and analytical tests based on the theory of hydrocarbon accumulation in faulted basins,the source rock,reservoir,cap rock and other elements of oil and gas reservoirs were dissected.Based on the study of reservoir forming conditions and main controlling factors of Dazhangtuo and Banqiao oil and gas reservoirs,the hydrocarbon accumulation model of the two regions was established.Through the superposition of the main controlling factors and the analogy of the conditions of oil and gas accumulation,the exploration potential direction of the lower exploration area of Es₁ in Banqiao sag is found,which provides scientific suggestions for the later oil and gas exploration.Two sets of high-quality source rocks,Es₃ and Es₁,are the main sources of oil and gas in Dazhangtuo and Banqiao reservoirs.The source rock in Es₃ has a high degree of evolution and the source rock in Es₁ has a low degree.The source of the Banqiao sag mainly comes from the Yanshan,the Xiaozhan and the Cangxian uplift.Due to the high terrain and steep slope of the Cangxian uplift,the Banqiao depression consists of gravity flow sedimentation and fan delta deposition.The reservoirs which have good physical properties and large thicknesses are mainly distributed in gravity channel sediments and fan deposits.The Es₁^z mudstone in Banqiao depression has a wide distribution and large thickness,which can be used as an effective cover for the Es₁reservoir in the study area.Es₁^x and Es₁^s have the characteristics of“storage and storage”and“self-storing”.The Dazhangtuo fault,the Banqiao fault and the Changlu fault are oil source faults,which have the ability to transport oil and gas,and are effectively arranged with sand bodies on both sides to control the accumulation of oil and gas on both sides of the fault.The hydrocarbon accumulation model of Dazhangtuo reservoir and Banqiao reservoir shows that the oil source-fracture-deposition controls the oil and gas enrichment in the Es₁.Based on this conclusion,it is found that the slopes and depressions on the northwest side of the Changlu fault in the Banqiao sag are favorable directions for oil and gas exploration in the Es₁ Member.