Study On Sedimentary Characteristics And Control Factors Of Low Permeability Reservoir In The First Member Of Funing Formation Of Gaoyou Sag

Based on the contrast and division of the first subsection of the first subsection of 1st member Funing formation,the sedimentary facies and distribution of sand body had been systematically studied.On the basis of diagenesis research,the related research work of diagenesis sequence and evolution and diagenesis type classification was carried out.The main control factors of the reservoir physical properties of the first subsection of 1st member Funing formation of the Gaoyou Sag were analyzed and summarized,and the reservoir evaluation and prediction were completed.Following achievements have been gained in this study.A short term base level cycle division and comparison scheme for the standard wells in the first subsection of 1st member Funing formation in Gaoyou Sag were established.Three sets of sand layer division standards for this set of strata were established.And more than 50 exploration wells were carried out.It was determined that the main source of the Gaoyou Sag in the first subperiod of the Funing formation sedimentary period came from the West and the northwest.In the southern part of the fault step zone,the fault activity was controlled,and the fan delta depositional system of the skirt like distribution was formed.The compaction and carbonate cementation were the main causes of low porosity and low permeability reservoirs in the reservoir.The change of ancient buried depth was the main reason for the obvious difference in the difference between the zones in the Gaoyou Sag.It was necessary to correctly evaluate the physical characteristics of the first subsection of the Fui section to the depth before the burial of the Yancheng formation.The secondary porosity formed by the dissolution was the main pore type of the oil bearing sandstone reservoir in the target layer.There was a correlation between the formation of secondary dissolution pores in oil bearing sandstone and the migration and accumulation of oil.According to the research results,the main types and distribution of the main diagenetic facies in the Gaoyou Sag were divided.The diagenesis and oil and gas filling are the main reasons for controlling the physical properties of the first subsection of 1st member Funing formation reservoir.The classification evaluation and prediction of the section were also carried out.During the project study,the exploration and production of Gaoyou sag was guided by the research results.Eleven pre exploration well positions were provided for the exploration of the Funing formation low permeability reservoir.Two wells of industrial oil flow were obtained.The newly increased probable reserves are 108.04×104t,the newly increased forecast reserves are 476.89×104t,and the newly increased oil is 2557 t.The breakthrough in the exploration of low permeability in the inner slope zone of the Gaoyou Sag has been realized.