Effect Of Displacement Pressure Gradient On Oil-water Relative Permeability In Ultra-high Water Cut Period

At present,China's onshore oil fields have entered the high and extra high water cut development period,and the microscopic occurrence of residual oil has changed significantly.The displacement conditions have a significant impact on the residual oil flow characteristics.Therefore,it is of great significance to carry out research on the influence of displacement pressure gradient on oil-water phase permeability curve.Firstly,the relative permeability of indoor oil and water under different core permeability,oil-water viscosity ratio and displacement pressure gradient conditions were used.The relative permeability was calculated by experimental data,and the core permeability,oil-water viscosity ratio and displacement pressure gradient were calculated.Relative permeability data.Secondly,the relative permeability data under different core permeability,oil-water viscosity ratio and displacement pressure gradient are analyzed and the changes of curve shape are compared to obtain the change law of oil-water relative permeability under different displacement conditions.Thirdly,using the quantitative study of the relative permeability change of oil and water,considering the core permeability,oil-water viscosity ratio and displacement pressure gradient factors,a new method for mathematical characterization of oil-water relative permeability in ultra-high water-cut oilfields is studied.Finally,using the new characterization method,the dynamic calculation and fitting of one-dimensional water-flooding oil considering the influence of displacement pressure gradient is carried out,and the suggestion of improving oil recovery is proposed.The study shows that when the core permeability and the oil-water viscosity ratio are constant,the residual oil saturation decreases with the displacement pressure gradient,the relative permeability of the water phase under the residual oil increases,the range of the twophase region increases,etc.When the displacement pressure gradient and the oil-water viscosity ratio are constant,as the core permeability increases,the irreducible water saturation and residual oil saturation decrease,and the relative permeability of the aqueous phase under residual oil increases.The range of the two-phase zone is increased,and the isotonic point is shifted to the left;when the displacement pressure gradient and the core permeability are constant,the greater the viscosity ratio of the oil-water,the smaller the irreducible water saturation,the greater the residual oil saturation,and the residual oil.The relative permeability of the lower aqueous phase increases,the range of the two-phase zone increases,and the isotonic point shifts to the left.