| This paper takes Chang 4+5 ultra-low permeability reservoir in Zoumaliang District as the research object,guided by multidisciplinary geological theory and methods,combined with regional geological situation,and makes full use of a large number of well logging,drilling,mud logging and experimental analysis data and oil testing and production testing data,use the research method of large-scale and dense well pattern to carry out fine division and comparison of strata,establish stratigraphic framework of the whole area,summarize stratigraphic characteristics,reveal structural evolution,and analyze sedimentary microfacies types and planar sedimentary facies belt development.It summarizes the characteristics of reservoirs,explains the distribution characteristics of caprocks,and comprehensively discusses the distribution characteristics,enrichment laws andcontrolling factors of oil and gas in reservoirs.The research results show that the Chang 4+5 strata in the study area are well developed and the thickness is stable,and the structure is generally elevated from west to east.The top surface structure of each sub-layer shows good inheritance.The Chang 4+5 oil layer group belongs to the delta front subfacies deposition,including four microfacies of underwater distributary channel,mouth bar,far sand bar and inter-distributary bay,among which the underwater distributary channel and mouth bar are the most developed.The lithology of the reservoir is fine sandstone,the intergranular pores are the main storage space,and the physical properties are poor.It is a low-porosity,ultra-ultra-low permeability reservoir with strong heterogeneity.Sedimentary facies strictly control sand body distribution and reservoir physical properties.The high oil saturation and high porosity and permeability areas are generally in good agreement with the main sedimentary facies belts of underwater distributary channels and mouth bars.Has a strong control effect.The low-amplitude nose uplift structure has a good directing effect and a certain control effect on oil and gas enrichment;reservoir heterogeneity also has a strong control effect on the distribution of oil and gas,mainly including sedimentary rhythm,interlayer density distribution and The control effect of the thickness distribution of the interlayers on the distribution of oil and gas;the development and distributionconditions of the caprocks,to a certain extent,promote the accumulation of oil and gas.The distribution of oil and gas is controlled by the dominant configuration of factors such as structure,sedimentation,reservoir and caprock,and the type of oil and gas reservoir is structural-lithologic reservoir. |
