Reservoir Characteristics Of Typical Field Profiles Of Shanxi Formation And The 8th Member Of Lower Shihezi Formation In Fugu-Baode Area

There are abundant tight gas resources in Shanxi Formation and the 8th member of Lower Shihezi Formation(He 8 Member)of Upper Paleozoic in the eastern Ordos Basin.The study of tight sandstone reservoir architecture,petrology,diagenesis and main controlling factors of reservoir physical properties is the key to realize efficient exploration and development.This dissertation is exemplified by the field section of Shanxi Formation and He 8 Member,Fugu-Baode,eastern Ordos Basin.With section measurement,thin section identification,grain size analysis and scanning electron microscopy etc,describing petrological characteristics and lithofacies characteristics,identifying architecture elements,summarizing spatial superposition of architecture elements,and then establishing of reservoir architecture model.The diagenetic characteristics,pore throat characteristics and physical characteristics of reservoirs are determined by using the techniques of carbon oxygen stable isotope analysis,physical property test and high pressure mercury pressure analysis.On this basis,multiple regression analysis is carried out to establish the regression equation of reservoir physical properties,and quantitatively characterize the control of sedimentation and diagenesis on reservoir physical properties.Furthermore,the reservoir architecture and physical properties in the profile are applied to the underground reservoir.And the core and logging data are used to analyze the architecture of the underground reservoir in Hangjinqi area.The rock types of tight sandstone reservoirs in the Shanxi Formation and He 8 Member of the Fugu-Baode area are mainly lithic sandstone and lithic quartz sandstone.The sortability of sandstone is good,and the compositional maturity is high.A total of 11 lithofacies types have been identified.The study area has identified six architectural units of channel filling(CH),longitudinal bar(LB),diagonal bar(DB),point bar(PB),abandoned channel(ACH),and floodplain(FF),transverse bar dams are generally not used as a separate architecture element.On this basis,the structural change characteristics and spatial superposition morphology of sandstone in the architecture element are clarified.And the braided river reservoir architecture model of Shanxi Formation and He 8 Member in the study area is established.Tight sandstone reservoirs have experienced strong compaction.The cementation is dominated by siliceous cementation and carbonate cementation.The objects of dissolution are mainly feldspar and rock cuttings.The pore type of reservoir is mainly intergranular pore.According to the characteristics of high pressure mercury injection curve,the reservoirs are divided into four types.The results of physical property regression show that the physical properties of Shanxi Formation reservoirs are mainly controlled by standard deviation,light mineral index,matrix content and dissolution strength.The regression equation of physical properties is established and the reservoir is evaluated.The results show that the beach has the best physical properties,followed by oblique sand dams and longitudinal sand dams,and channel filling properties are the worst.The physical properties of the He 8 Member reservoir are mainly controlled by the average particle size,standard deviation,matrix content and dissolution strength.The results show that the physical properties change from good to bad,in turn obliquely towards sand dams,channel filling,and longitudinal sand dams.Based on core data and logging data,three architectural units of floodplain,sand bar,and channel filling were identified in Hangjinqi area.The physical properties of the underground reservoir architectural unit are basically consistent with the analysis of outcrop samples.