The Study On Characteristics Of Chang 4+5?Chang 6 Reservoirs And Favorable?Area Prediction In Central And Southern Regions In Hengshan Oilfield

Combined with petroleum geology,sedimentology and reservoir geology,this article researches the Chang 4+5 and Chang 6 reservoir groups of Hengshan oilfield in central and southern regions.Based on well drilling and logging data,core observation,formation testing,and section analysis and also with the test methods,such as scanning electron microscopy,mercury penetration,X-ray diffraction and so on,The author do deep and systematic researches on the sedimentary facies and reservoir of the target reservoir group.According to this study,and with the petroleum accumulation regulation,we have a forecast to the favorable exploring area.According to the distribution of lithology,electrical,sedimentary rhythm and regional key bed,the Chang 4+5 and Chang 6 reservoir groups can be divided into several small oil-bearing series named Chang 4+5~1,Chang 4+5~2,Chang 6~1? Chang 6~4.Based on fine stratigraphic correlation,the top surface structure of each layer is the monoclinic,inclining to the west.The deposition of the Chang 4+5 and Chang 6 reservoir groups belongs to a set of lake delta faces deposition.The research region Chang 4+5 and Chang 6 are Delta plain subfacies and Delta front subfacies deposition.By the sedimentary microfacies of single well to be seen,rivers flow from north-east to south-west in the study area.For the main rock type is fine – medium fine-grained feldspar sandstone and feldspar lithic sandstone,and residual intergranular pores give the first place to the the pore type,the reservoir physical properties are poor,belonging to a special low porosity-low permeability reservoirs.The diagenesis study shows that Chang 4+5 and Chang 6 Reservoir diagenetic evolution has reached diagenetic A period,the mainly experienced diagenesis are compaction,pressure solution,cementation,metasomatism,dissolution and fracturing.The reservoir layer and interlayer heterogeneity are strong.The petroleum accumulation of Chang 4+5 and Chang 6 are mainly controlled by sedimentary facies,reservoir physical properties.The target group is lithologic reservoir,which is mainly distributed in the thick sandbodies with relatively good physical properties of the main channel.