PETROLEUM MIGRATION SYSTEM AND NEOGENE PETROLEUM ACCUMULATION FEATURFS IN THE BAXIAN SAG, BOHAI BAY BASIN

Neogene reservoirs are mainly distributed in Guantao Formation of Wen'an slope,the Baxian Sag of the Bohai Bay Basin.Reservoir types are fault nose reservoirs and fault block reservoirs controlled by fault.The distribution of reservoir is clearly subjected to effective migration system.By studing oil and gas shows,effective pore space,fluid properties and nitrogen compounds,effective migration system and petroleum accumulation features in Wen'an slop area are analyzed.And accumulation models of Neocene reservoirs are established.Studies have shown,the passage system in the study area is made up of sand bodies,faults and unconformities.Oil and gas is mainly from source rocks in Es₁ subsection,then it migrates through sand bodies of upper Es₁ subsection,Dongying Formation and Guantao Formation,faults and unconformities.With the increasing migration distance,migration horizons are getting newer,in the end it gathered in Neogene strata of the Wen'an slope.