Study On Logging Evaluation Method Of Seepage Barrier Coupling With Vertical Well And Horizontal Well

The reservoir in the Paloch oilfield in South Sudan is highly heterogeneous,and the oilfield has entered a stage of high water cut,and the form of water control and oil stabilization is severe.At the same time,the sedimentary environment is the main oil-bearing strata of the braided and meandering rivers(Yabus group and In the Samma group,the origin and distribution model of the mature seepage barrier have not yet been established.Therefore,it is urgent to conduct an in-depth study of the seepage barrier in the Paloch oil field,to clarify the genetic type of the seepage barrier and to finely describe its interwell distribution to provide theoretical guidance for water injection and well network adjustment in the later stage of the reservoir.Based on the core observation description,vertical well and horizontal well data,the study area is divided into reservoir lithofacies and seepage barrier facies by quantitative identification of principal component analysis.On this basis,the seepage barrier facies is further divided into four genetic types by grey theory method,namely flooding and overbank sedimentary seepage barrier,abandoned channel sedimentary seepage barrier,retention gravel sedimentary seepage barrier,lateral deposit layer and silting layer sedimentary seepage barrier.Based on the single well quantitative identification of seepage barrier,the lithofacies,genetic type,thickness and distribution of the seepage barrier are extracted.On this basis,a method for predicting the distribution of seepage barrier between vertical and horizontal wells is proposed.That is to say,the stratum is divided into stratums,the horizontal well is regarded as the “bridge” between the vertical well and the vertical well,and the distribution of the seepage barrier between the wells is characterized.The rationality of the prediction of the seepage barrier distribution is verified by the production dynamic data analysis.Finally,the distribution law of seepage barrier in the study area is summarized,and its effect on fluid seepage and residual oil is analyzed.