Research On Influence Factors And Solution Methods For Mathematical Model Of Oil Displacement By Water In Porous Media

The water-oil phase flow theory is one core part of the reservoir engineering theory and practice.Fractional flow equation and displacement front has always been the most concerned issues.Studying on the law of the water-oil phase flow is very significant for understanding the flooding dynamic,optimization of flooding program and increasing the displacement efficiency.This paper summarizes the classical methods of reservoir displacement theory,the characterization method and the dynamic analysis method of water cut and the displacement front in literature research.A mathematical model of displacement front that comprehensively considers gravity and capillary force is established,and an analytical solution is obtained.The thesis uses the seepage mechanics and numerical simulation methods to analyze and mathematical characterize the influence factors of the displacement fronts,pressure profile,and water cut by using actual Oilfield production data.The main achievements of this paper are as follows:(1)The applicability of classical displacement theory and B-L model is analyzed.The effect of different factors on oil-water phase flow is studied by analyzing the seepage laws and characteristic parameters of water-drive reservoirs.(2)The characteristics method,traveling wave method and Painleve method are used to explore the solution of the B-L equation.(3)Collect and arrange the phase permeability data of multiple actual reservoirs,used to verify the three forms of water cut curve,fit the water cut and water cut derivative curve,and get the exponential,logarithmic,flat,vertical,etc.of the fitted equation.(4)The fitted equation are used to obtain the analytical solution of the B-L equation.Through data analysis to study the influence of different factors on the displacement front,verify the correctness of the mathematical model and its analytical solution.(5)Through numerical simulation method and model of reservoir geological parameters,the reservoir evaluation of development effect under different influencing factors is simulated,which further shows that gravity is one of the main driving forces for the migration and reassemble of residual oil in high water cut reservoirs.(6)The increase in density contrast and dip angle results in a smaller the water cut of the reservoir,a slower movement of the displacement front,and the oil displacement efficiency is better.The capillary force makes the water cut increase and the shape of the displacement front change,but the oil displacement efficiency remains unchanged.