Research On Characteristics And The Prediction For Favorable Reservoir Distribution In Tight Reservoir In Es₄-Ek₁ Of South-Central Jinxian Sag

The tight reservoir in Es₄-Ek₁ of South-central Jinxian Sag is rich in oil and gas resources.But now the characteristics and the main controlling factors of tight reservoir are not clear,which restricts the development in research area.To solve these problems,we carried out the research about characteristics and the prediction for favorable reservoir distribution in tight reservoir in Es₄-Ek₁ of South-central Jinxian Sag.On the basis of predecessors,combining with the information of core,mud logging,well log data and analytical experiment,this paper made a comprehensive analysis and evaluation to predict favorable reservoir distribution from sedimentary characteristics,diagenetic characteristics,pressure characteristics,source rock evaluation and reservoir microscopic characterization.The main sedimentary facies which are developed in the study area are braided river delta facies,fan delta facies,lacustrine facies.The main diagenetic processes that have affected the tight sandstones include compaction,cementation dissolution and recrystallization.The early compaction and carbonate cementation resulted in loss of great and dissolution improved reservoir quality.Glutenite reservoir space in Es₄-Ek₁ of South-central Jinxian Sag is mainly pore type and pore-fracture pore.Pore include primary pore,secondary pore and intergranular pore;fracture is divided into structural fracture and fracturing fracture.Reduced-neck,silm,fine tube and cluster pore throat occurring is the main throat type.The necking throat is locally developed and the laminated throat or the curved lamellar throat is mainly developed and the control shape throat is relatively developed.According to core observation,mud logging,well log data and all kinds of experimental methods of micro pore throat structure characterization,we determined the type of sedimentary facies,diagenesis,pressure characteristics,hydrocarbon source rock distribution,physical property distribution and pore throat types in the study area.And on this basis,we determined the main controlling factors for the development of favorable reservoir.Both sedimentary characteristic and diagenetic characteristic played very important roles in the development of reservoir.The distribution diagram of sedimentary facies,pressure characteristics,hydrocarbon source rock and physical property are drew to predict favorable areas in South-central of Jinxian Sag.