Study On Strata Classification And Exploitation Strategies Of Medium-High Permeability Multi-Layer Reservoirs In Extra High Water Cut

After multiple subdivision and recombination,multi-layer fault block reservoirs enter the late stage of ultra-high water cut development.The heterogeneity between layers of multi-layer reservoirs leads to interlayer interference phenomenon.How to improve the interlayer interference phenomenon and explore the residual potential of such reservoirs is a big problem we are faced with.On the basis of considering the difference of interlayer reservoir physical property and remaining oil distribution,this paper analyzes the influencing factors of interlayer interference,establishes the stratigraphic block classification model of multilayer reservoir in the super high water cut period,and puts forward the corresponding development countermeasures and policy limits,which can be applied to the oilfield development.Xin 50 fault block reservoir formation in 2008 restructuring,based on the Xin 50 fault block oil reservoir physical property parameter multilayer model is set up,by quantitative analysis of restructuring of recovery degree influence on residual oil distribution,and the interlayer stress analysis found that the interlayer water quantity differences cause interlayer interference,on the basis of interlayer water quantity differences interlayer interference quantitative characterization method is established.Based on the interlayer interference coefficient,the main controlling factors of interlayer interference were analyzed to determine their sensitivity,and the policy limits of influencing factors of interlayer interference were analyzed to study the mechanism and methods of mitigating interlayer interference.Based on the reservoir physical property and development index of Xin 50 fault block combined with the boundary of interlayer interference factors,the stratified blocks were classified into four types.According to the characteristics of each block,measures such as low permeability layer fracturing and radial drilling were taken,and the policy boundary of each measure was obtained.Combined with economic factors and oil phase fluidity,the screening process of strata recombination scheme is put forward,and permeability limits are obtained according to economic factors.According to the stratigraphic classification standard,the reservoir layers of Xin 50 fault block are divided,and the optimal plan of recombination of reservoir layers of Xin50 fault block is screened out considering economic factors and oil phase fluidity,so as to improve reservoir recovery.The results show that the difference of interlayer physical properties leads to the difference of water absorption,which leads to interlayer interference.The influencing factors of interlayer interference are oil saturation,permeability,crude oil viscosity and injection-production pressure difference.According to the single well technology cumulative oil production > single well benefit cumulative oil production,under the condition of oil price of 50$/b and well spacing of 300 m,the oil saturation level difference limit is 1.2,permeability level difference limit is 3,crude oil viscosity level difference limit is 2,and small layer thickness level difference limit is 1.5.