Yanchang Formation,north Of Huangjialing District,fuxian Oilfield,ordos Basin Reservoir Characteristics Of Chang 8 Oil Layer Group

In this paper,the sedimentary microfacies and sand body distribution characteristics of the Chang 8 oil layer group were studied by observing the core,analyzing logging data and scanning electron microscopy;Using physical property tests,observation of cast flakes and X-diffraction analysis,the petrology type,reservoir physical properties and heterogeneity of the Chang 8 oil layer group were analyzed;Use high-pressure and constant-speed mercury pressure experiments to study the reservoir space in the reservoir;through the reservoir sensitivity experiment data,analyze the reservoir sensitivity characteristics;Through the inclusion temperature measurement experiment,the accumulation period was analyzed.Based on the analysis of reservoir characteristics,the controlling factors of the reservoir are studied,and the quantitative characteristic parameters are combined to classify and comprehensively evaluate the reservoir.The northern part of the Huangjialing area is located in the southeast of the Ordos Basin and belongs to the northern Shaanxi slope tectonic unit.The Chang 8 oil layer group is one of the reservoirs with large development potential in the study area.The geological conditions of the Chang 8 oil layer group in the study area are complex,the reservoir physical property changes are large,the oil-bearing sand bodies are large,and the development is difficult,which seriously affects the development effect of the area.Provide reference for exploration and development work to ensure the efficiency of water injection development,improve oil recovery,and achieve stable and high production in the long term.The structural characteristics of the Chang 8 oil layer group in the study area are consistent with the regional tectonic background,which is a gentle west-dipping monoclinic,locally developed low-amplitude nose-like uplift.The Chang 8 oil layer group is mainly delta front subfacies deposits,with the development of underwater distributary channels and distributary bays.Its lithology is mainly light gray,gray fine-grained,medium-fine-grained feldspar sandstone.The debris component is mainly feldspar.The cementing type is mainly pore and pore-contact type,and the pore type is mainly intergranular pore.The sandstone porosity of Chang 8 oil layer group is 2.1%-13.7%;the permeability is 0.024×10^-3?m²-1.50×10^-3?m²,which belongs to low-ultra-low porosity and ultra-low ultra-low permeability reservoirs.The rock formation of Chang 8 oil layer mainly includes compaction,cementation,dissolution,metasomatism and rupture.The Chang 8oil layer group mainly develops Type?and Type?reservoirs,Type?is mainly distributed in the middle of the study area;Type?areas are distributed in the west and north of the study area;Type?areas are distributed in the east and northwest of the study area;Type?areas are distributed in the southeast and north of the study area.