Effective Reservoir Distribution Prediction And Heterogeneity Study Of Upper Es4 Member In Yong 559 Area

Yong 559 oil field is located in the north of steep slope belt in Dongying depression.The sedimentary background of the upper sub-member of the fourth member of Shahejie Formation is the nearshore subaqueous fan which deposited during the active period of the faulted lacustrine basin.There are some problems in the study area,that is the unclear sand body distribution pattern,difficult sedimentary facies recovery and strong reservoir heterogeneity.Therefore,this paper is aimed to rebuild the sedimentary model and predict the distribution of sand body by the way of combining the well and seismic data.On the basis of this work,effective reservoir prediction and reservoir heterogeneity have been accomplished.Guided by the basic theories of sedimentology and reservoir geology,it has been comprehensively analyzed the core lithology,thin section identification,mercury injection and particle size analysis and other data,together with the integrated logging curve characteristics to conduct the division of sedimentary microfacies in single well.The nonlinear calculation model of seismic attributes and sand body thickness is established by machine learning algorithm,which contributes to constrain the plane distributive characteristics of sand and predict the interwell sand body distribution.Based on the single well facies and well section facies,the plane distribution of sedimentary microfacies has been studied.According to the relationship between the experimental pore and permeability data and logging curve,the porosity interpretation model and permeability calculation model are established to predict the plane distribution of pore and permeability under the control of sedimentary phrase.The effective petrophysical cutoff properties of the oil reservoir are determined by empirical statistical method and oil-bearing occurrence.The plane distribution characteristics of effective reservoirs can be predicted by comprehensively integrating sedimentary facies,pore-permeability plane distribution and cutoff properties of the oil reservoir.In this paper,it is concluded that there are central fan subfacies and marginal fan subfacies in the target interval.The direction of braided channels is from northwest to southeast.The development of sand body controls the reservoir distribution.It is indicated that 6% and 3 m D are the thresholds for porosity and permeability of prospective reservoirs,respectively.It belongs to low-porosity and low-permeability reservoir.According to the thresholds of petrophysical of reservoir and sedimentary facies characteristics,the effective reservoir distribution range is identified,which shows the banding-fan shape.The effective reservoir distribution is reduced from bottom to top stratum.The study of reservoir heterogeneity is carried out from three aspects: in-layer,interlayer and plane heterogeneity.It shows that the reservoir is highly heterogeneous,which is mainly controlled by sedimentary facies.There are many shale interlayers and mudstone barriers in the study area,which make great contribution to reservoir heterogeneity.