| Panlong area of the study area is located in the eastern part of the slope of northern Shaanxi,and the target layer is Chang 2 and Chang 6 oil formation of Triassic Yanchang formation.by using the experimental reports of core,grain size,mercury injection and physical properties in the study area,as well as the microscopic data of cast thin section,cathodoluminescence and scanning electron microscope,the reservoir difference characteristics of the target layer are analyzed in detail.In this paper,the influence of sedimentation and diagenesis on reservoir characteristics is discussed from four aspects: reservoir petrological characteristics,physical properties,reservoir space types and pore structure characteristics.Through research,it can be concluded that the differences between Chang 2 and Chang 6 reservoirs are mainly reflected in: feldspar and quartz content,particle size,sorting and roundness,porosity and permeability,the development of intergranular pores and dissolved pores,and the correlation of pore throat characteristic.Chang 2 has the characteristics of relatively high quartz,low feldspar content,coarse particle size,poor roundness of sorting,excellent pore permeability performance,well-developed intergranular pores,coarse and insufficient pore throat particle size,and good pore throat connectivity;Chang 6 is characterized by low quartz,high feldspar content,fine particle size,good separation and roundness,poor pore permeability,relatively developed dissolved pores,fine and uniform pore throat particle size,and poor pore throat connectivity.The difference between Chang 2 and Chang 6 reservoirs is caused by sedimentation and diagenesis.Among them,the sedimentary microfacies affect the distribution of sand bodies and the development of high porosity and permeability,and the grain size,sorting and clastic components also affect the reservoir physical properties to a certain extent,resulting in the difference of reservoir physical properties.Diagenesis can transform the physical properties of the reservoir,in which compaction and cementation will reduce the porosity and permeability of the reservoir,while dissolution has a positive effect on the physical properties. |
