Study On Sedimentary Microfacies And Reservoir Characteristics Of Chang 4+5 In Well X Area,Anbian Area

The X well area in Anbian area is located in the middle of the northern Shaanxi slope and is rich in oil and gas resources.Its Yanchang Formation 4+5 is one of the important exploration and development intervals in the Ordos Basin in recent years.Combining the logging curves of Chang 4+5 section in the well area and laboratory data,comprehensive use of core observation,casting thin section,scanning electron microscope,mercury intrusion method,porosity and permeability measurement and other technical methods are used to analyze sedimentary microfacies and reservoirs.Characteristics were studied.The results show that the length 4+5 of Well X in Anbian area is a set of lacustrine delta deposits,with delta front subfacies developed,and can be subdivided into four types:underwater distributary channel,estuary dam,distributary bay,and underwater natural dike Microphase.The reservoir rock types are mainly feldspar sandstone and lithic feldspar sandstone,and the reservoir space is mainly composed of intergranular pores and feldspar dissolved pores composed of intergranular pores-dissolved pores.Diagenesis is both destructive and constructive to the reservoir.Compaction and the cementation of clay minerals,siliceous and calcareous are the main reasons for the compactness of the reservoir.The dissolution of feldspar particles and some cements is beneficial The preservation of primary pores improves the quality of the reservoir.It can identify three main types of throats,medium and fine throats,micro throats and micro throats.The porosity is mainly between 9.2%?16.5%,and the permeability is generally 0.15?0.56×10^-3?m².It belongs to low porosity and low permeability fine throat.Type reservoir.Based on the research results of sedimentary microfacies,sand body distribution and physical properties,the Chang 4+5 reservoirs in the X well area in Anbian area are classified into standardized categories,which are mainly divided into type I reservoirs,type II reservoirs and type III reservoirs.Among them,the underwater distributary channel microfacies is most conducive to the development of the reservoir,and the reservoir types are mainly type II and III.