Recovery Of Paleopressure And Paleo-fluid Potential Of Funing Formation In Gaoyou Sag

Gaoyou Sag is the most abundant oil and gas reservoir in northern Jiangsu Basin,with the highest resource abundance and the most abundant reserves.But there is no systematic study and deeper understanding of paleopressure and paleo-fluid potential.Therefore,this article uses the analysis and testing method of fluid inclusions to regain the paleopressure in the reservoir of Funing Formation in Gaoyou Sag,and recover the paleo-fluid potential at the critical moment based on England theory,revealing the history of oil and gas migration.The results show that there are two oil and gas filling in the reservoir of Funing Formation.The main accumulation period is around 37 Ma,that is,the critical moment.From 37 Ma to 23 Ma,the formation pressure decreases rapidly,and it increases slowly after 23 Ma,but it does not reach the highest level in history.The distribution range of abnormal high pressure in the reservoir of the first member of Funing Formation is obviously larger than that of the third member.The change trend of ancient pressure in two layers is consistent,and the ancient pressure coefficient decreases from south east to north and west.The high value of abnormal pressure in the first member of Funing Formation is higher than that in the third member.The capillary radius of reservoir and the fluid potential of Funing Formation reservoir are restored.The fluid potential of the study area is the highest in the 37 Ma period,the fluid potential of the third member of Funing Formation reservoir is smaller than that of the first member.The development of abnormal high pressure inhibits the diagenesis of reservoirs to a certain extent,saving the reservoir space of oil and gas.There are three kinds of oil and gas migration dynamic types: the source is abnormal high pressure type,buoyancy-abnormal pressure mixed type and source external steep slope zone buoyancy type.Fluid potential energy distribution and oil and gas distribution has a good matching relationship,in the fluid potential gradient dense high potential to low potential transition zone is the relative activity area of oil and gas migration,which can be used as an advantage exploration area.