Study On Characterization And Reconstruction Method Of Flow Field In High Water Cut Period Reservoir

At present,most of the eastern oilfields in China have entered the late stage of high water cut development,with a comprehensive moisture content of over 90% and an oil recovery of less than 30%.In order to improve oil and gas recovery,the flow field must be qualitatively and quantitatively described,and the variation law of the underground flow field should be revealed from the perspective of dynamic evolution.First of all,according to the needs of flow field reconstruction measures,two types of indicators are proposed: one type of indicators are indicators for guiding measures,including remaining oil potential,hydrodynamic intensity and streamline attributes,and the other type of measure is the evaluation of measures.The indicators include residual oil dispersion,flow heterogeneity and traditional recovery degree indicators,and demonstrate the rationality of the calculation methods for each indicator.Secondly,the evaluation method of flow field in high water cut period is established,which is to study the regularity and adaptability of each flow field characterization index: for scalar flow field,the reservoir can be divided into low potential & high hydrodynamic,high potential & low hydrodynamic,high potential &low hydrodynamic,and low potential & low hydrodynamic four-scalar flow field types,different types of regional reconstruction measures are different;for vector flow field,under fixed well network conditions,the streamline bundle flow rate between injection-production wells is relatively stable,and the streamline bundle potential and the streamline bundle oil cut tend to become smaller with time.For the remaining oil dispersion,the typical curve generally includes four stages: a steady rise phase,a rapid rise phase,a fluctuation decline phase,and second steady rise phase,the effectiveness of the reconstitution measures can be judged by the trend of the residual oil dispersion after the reconstruction measures;for the flow heterogeneity,the variation curve generally includes the unstable phase and the stable phase,and the stability phase values can reflect the heterogeneity of the flow field.The larger the value,the stronger the flow field heterogeneity.Thirdly,the flow field reconstruction method in high water cut period is established,that is,the flow field reconstruction measures such as drilling new well,well net thinning and profile control and water shutoff according to scalar flow field are carried out,and liquid flow optimization is carried out according to vector flow field,and three liquid volume optimization strategies for streamline bundle flow,streamline bundle potential and streamline bundle oil cut were proposed,and the effectiveness of the measures was evaluated by using residual oil dispersion and flow heterogeneity.Finally,the flow field of E block was evaluated,and the flow field reconstruction measures such as drilling new well,well pattern thinning and liquid volume optimization were developed,and the effectiveness of the refactoring measures was evaluated by using the residual oil dispersion,flow heterogeneity and recovery degree index.It is found that after the flow field reconstruction,the Lorentz coefficient of the E block reservoir is reduced and tends to be gentle;the degree of recovery is significantly improved,which is 3.76 percentage points higher than the basic scheme.It provides a new technical means for the comprehensive adjustment of high-water-bearing oilfield development.