The Study On The Characteristics And Main Control Factors Of Tight Reservoirs In Fuxian Exploration Area,Yanchang Oilfield

Based on the data of drilling,logging,analysis and testing,this study is based on the data of drilling,logging,analysis and testing.Through a large number of core observation,thin slice identification,electron probe,scanning electron microscopy,logging interpretation,high-pressure mercury pressure,and field quality investigation,the 8 oil formation group in this area The profile of the dense reservoir is analyzed,and the stratigraphic division and comparison of the target layer,the development and distribution of sedimentary facies,the petrological characteristics of the reservoir and the micro porosity and permeability of the reservoir are studied.Finally,based on the above research results,the reservoir is evaluated synthetically,and the reservoir is on the basis of this study.The main factors of control are studied.The lithology of the reservoir in the study area is dominated by feldspar sandstone and medium fine lithic feldspar sandstone.It belongs to the delta front subfacies deposit with an average porosity of 8.12%and an average permeability of 0.25×10^-3?m²,which belongs to low porosity,ultra low permeability and ultralow permeability reservoirs.The pore structure of Chang 8 reservoir is complex.Its main pore types are primary intergranular residual pore and feldspar dissolved pore,and Kong Hou type belongs to micropore and fine throat type.The Chang 8 reservoir in the study area has the characteristics of weak velocity sensitivity,moderate weak salt sensitivity and acid sensitivity,weak water sensitivity and weak alkali sensitivity.The main diagenesis of Chang 8 reservoir is tight compaction,cementation,metasomatism,dissolution and fracturing.The two diagenetic evolution stages are reservoir forming stage and early diagenetic stage.The non homogeneity of the dense reservoir in the Chang 8 reservoir is strong,and the heterogeneity in the layer is medium,but the interlayer heterogeneity,the long and 81 interlayer heterogeneity are strong,but the long 82 layers are weak.The main control factors of reservoir performance in this area are sedimentary microfacies,diagenesis,source rock development,sufficient supply of oil source and flat structure,which are most important for sedimentary microfacies and diagenesis.