Abstract: More and more researchers have attached importance to the influence of interfacial characteristics (interfacial rheological behavior,interfacial tension behavior and wettability) on oil displacement process.In this paper,the porous medium of reservoir is simplified as a model of undulating pipe which has the behavior of cyclical contraction-expansion.Based on the energy equilibrium principle,a mathematical model between interfacial characteristic parameters and displacement velocity is set up,finite difference method is used to solve the mathematical model.The influence of interfacial viscosity,interfacial tension and wetting angle on interfacial velocity is analyzed.It is indicated that the change of wettability affects displacing velocity,when the directions of interfacial curvature and displacement are contrary,the dimensionless interfacial axial displacing velocity decreases with the increase in the dimensionless interfacial tension and viscosity,and the interfacial axial displacing velocity is asymmetric about the centre of pore unit

Key words: polymer solution, undulating tube, interfacial tension, interfacial viscosity, wetting angle