Study On Optimization Of Injection-production Parameters Of Strata Reorganization In Eastern Xingsan Block

After entering the period of ultra-high water saturation in the eastern part of Xingsan Block,located in Xingbei Development Zone,Daqing Oilfield,three infills were carried out.Due to long-term water injection,the main streamline of oil and water wells became highly saturated with water,while the non-main streamlines remained less saturated.As a result,injected water crossed along the main streamline,causing a high water cut in oil wells and low water injection efficiency.To enhance the effectiveness of water flooding development,a layer system reorganization was implemented in the eastern part of Xingsan Block,a typical block,in 2013.The reorganization led to a change in the position of oil and water wells in the layer system,altering the streamline and effectively utilizing the remaining oil of the non-main streamlines.Initially,the results were promising.However,over time,the development effect weakened.Therefore,optimizing the injection-production parameters after layer reorganization,determining reasonable injection-production parameter limits,and further improving the development effect are necessary.In this study,the Petrel geological modeling software was utilized in conjunction with research findings on sedimentary microfacies to establish a detailed geological model of the eastern region of Xingsan Block.The Eclipse reservoir numerical simulation software was then employed to conduct fine history matching and compare the distribution characteristics of remaining oil in the plane and vertical directions before and after layer recombination.The streamline analysis method was employed to investigate and compare the evolution of streamlines before and after the reorganization of each oil layer,and the mechanism of remaining oil production in non-main streamlines was thoroughly studied and analyzed,providing a theoretical basis for optimizing reasonable injection and production parameters after the layer system’s reorganization.Then,the numerical simulation method was used to examine the impact of different formation pressures on remaining oil and changes in recovery factors,leading to the determination of the reasonable formation pressure level of different strata.The reasonable pressure coefficients for the three strata sets below Saertu A,Saertu B,and Pu I4 are 0.95～1.05 MPa,1.05～1.15 MPa,and 1.1～1.2 MPa,respectively.Based on the current formation pressure,a reasonable pressure recovery rate is proposed,and an optimal injection-production ratio is determined.The flow pressure of the oil well and water injection pressure of the water well are determined using a reservoir engineering method that considers pump efficiency and fracture pressure.By applying the Buckler-Leverett equation and considering the relatively uniform displacement of various reservoirs,the reasonable liquid production and water injection intensities are determined.The measures for exploiting the remaining oil potential in each layer and for treating low-efficiency wells are proposed based on the classification of low-efficiency wells.The numerical simulation results show that the implementation of the injection-production parameter optimization scheme increases the recovery rates of the three sets of strata below Saertu A,Saertu B,and Pu I4 by 0.80%,1.10%,and 1.20%,respectively.To simplify the calculation process and facilitate field application,a reservoir engineering method is used to establish the prediction model for the development index law of each layer after the layer reorganization.The 10-year development index of each layer is predicted,and the change in the development index after the layer reorganization is clarified,providing a reference for formulating oilfield development planning.