Reservoir Characteristics And Reservoir-forming Regularity In YanChang Formation Of Bai-Yanjing Region

Chang-8 and Chang-6 members in YanChang Formation of Bai-YanJing Region are taken as the major study object in this thesis.Under the guidance of theories of sequence stratigraphy?petroleum geology?well logging?geophysics and geochemistry,on the basis of abundant data from geology,drilling,logging,seismic,oil testing,adopting the combination of geology?geophysics?geochemistry and technique methods of geology research indoors and in the field,using many testing and analytical methods,Chang-8 and Chang-6 members are deeply studied in strata?structure?sediment?reservoir and characteristics of oil storage.Based on the methods,this paper discusses the regularity and controlling factors of the accumulation and distribution of oil-gas,forecasting favorable areas in this study area.The main understanding and conclusions are as followed:According to "marker layer?cyclic correlation control",YanChang formation is divided,and then the detailed stratigraphic framework is builded.According to the analysis of faces signs,such as rock types and features?sedimentary structure?fossils in this study area,and combined with the regional sedimentary background,the deposition of Chang-8 member is a delta front sedimentary system and Chang-6 is a fan delta front sedimentary system.The sandstone of Chang-8 reservoir in the study area is feldspar sandstone and Chang-6 is mainly lithic feldspar sandstone.Both the types of porosity are mainly intergranular pores,and the type of reservoir is low porosity extra special low permeability reservoir.Through the interpretation of profile and analysis of stratigraphic correlation,determining the distribution characteristics and sealing of fault.The paper also concludes the regularity of the accumulation of Chang-8 and Chang-6 reservoir,which shows the study area is controlled by delta front distributary channel under water where is considered as the most important area.The good regional cap rock of interdistributary bay also supplies good barrier conditions.According to the type and distribution of reservoir and based on previous studies,the research concludes the mainly reservoir-forming model:fault—migration though migration layer system—accumulation in anticline structure—Mesozoic reservoir-forming.