Study On Remaining Oil Distribution And Adjustment In Low Permeability Y Oilfield

Low permeability reservoirs account for more than half of the annual new reserves in China,so the effective development of low permeability reservoirs is of great significance.Because the pore size of low permeability reservoir reaches micron level,the seepage characteristics of low permeability reservoir are significantly different from those of medium high permeability reservoir due to the influence of micro scale and boundary layer effect.The seepage flow no longer meets the Darcy flow,but presents nonlinear seepage characteristics.The current commercial numerical simulation methods are based on Darcy’s law,which optimistically exaggerates the percolation capacity of low-permeability reservoir,leading to large prediction development index,seriously affecting the objective evaluation and planning production of remaining oil distribution in low-permeability reservoir.In view of the above problems,the research and software implementation of non-linear numerical simulation method for low permeability reservoir is an indispensable step for reasonable evaluation of such oilfield,and also the basis for formulating adjustment measures for low permeability reservoir.This paper analyzes the seepage characteristics of low permeability reservoir,summarizes the characteristics of each low permeability reservoir seepage model,and finally improves the nonlinear numerical simulator which can accurately simulate the characteristics of low permeability reservoir based on Jiang’s low permeability nonlinear seepage theoretical model with clear physical meaning and rich connotation.The nonlinear parameters affect the curvature of the low-permeability nonlinear flow curve and the pseudo threshold pressure gradient of the low-permeability reservoir,and then affect the numerical simulation evaluation of the whole low-permeability reservoir.By comparing the characteristics of oil saturation distribution and production index of different models,such as Darcy model,pseudo start-up pressure gradient model and nonlinear model,it is found that the nonlinear model can predict the development index of low permeability reservoir more reasonably;The influence of key parameters in ginger nonlinear model on development index and remaining oil distribution characteristics is analyzed.The target block Y belongs to low permeability reservoir.Based on Y block,the key well group is selected as the research object.Considering the non-linear seepage characteristics of low permeability reservoir,the well group index is fitted by the nonlinear numerical simulation of low permeability reservoir.On this basis,the distribution characteristics of remaining oil in the formation are analyzed,the contradiction of reservoir development is studied,and the corresponding adjustment measures are formulated according to the distribution types of remaining oil and the contradiction of reservoir development.Through the measures of water plugging optimization,stratified water injection and liquid volume adjustment,the potential of remaining oil can be effectively tapped.