Research On The Characteristics Of Chang 7 Reservoir In The West Of Xin'anbian,Ordos Basin

In this paper,guided by the theories of sedimentary petrology and reservoir geology,through various analysis and testing methods such as core observation,casting thin section,scanning electron microscope and mercury intrusion experiment,the petrological characteristics of the study area,Carry out systematic research on sedimentary characteristics,pore structure,diagenesis and reservoir heterogeneity.The Chang 7 reservoir in the study area belongs to the delta deep-water sedimentary system of the lake basin.It mainly develops delta fronts and semi-deep lake-deep lake subfacies and includes sedimentary microfacies such as underwater distributary channels,interdistributary bays and estuary bars;rock particles in the reservoir Mainly gray-white fine-grained feldspar sandstone and lithic sandstone;the pore space type of the reservoir is mainly composed of intergranular pores and feldspar dissolved pores;the diagenesis experienced during the diagenesis of sediments includes:compaction and pressure solution,cementation,Metasomatism and dissolution,among which compaction and dissolution and cementation are the main reasons for the tightness of the reservoir in the study area.The large number of dissolved pores produced by dissolution improves the reservoir performance.According to the analysis of vitrinite reflectance,inter-particle contact relationship and pore type,it is concluded that the reservoir in the study area has reached the middle diagenetic stage A-B.Research on the reservoir heterogeneity through intralayer heterogeneity parameters,interlayer heterogeneity parameters,and planar heterogeneity,etc.,and finally judged that the Chang 7 reservoir belongs to the medium heterogeneity-homogeneous type.Floor.By analyzing evaluation parameters such as reservoir permeability,porosity and sand body thickness,it can be seen that in the Chang 7₁and Chang 7₂layers,type I and type II reservoirs are widely developed,with good physical properties and connectivity,and the Chang 7₃layer is not developed in type I,and type II.The species is widely developed,and the physical properties and connectivity are poor.