The Effect Of Capillary Number On Oil Displacement Efficiency Of Polymer-surfactant System

The rheology of different polymer solutions and different polymer-surfactant solutionswere measured by HAAKE RS150rheometer. The influence of mass concentration, molecularweight on the rheology of polymer solutions and polymer-surfactant solutions were studied.Through short core seepage experiment, the influences of capillary number on displacementefficiency and residual oil saturation is studied. The influences of mass concentration,molecular weight on the capillary number were also studied. Results showed that: with theincrease in the relative molecular and mass concentration of polymer, the viscosity andelasticity are enhanced, The system can significantly improve oil displacement effect. Forpolymer-surfactant binary system, with the capillary number increases, the oil displacementefficiency increases, the residual oil saturation increases. on the capillary number and oildisplacement efficiency curves, both the oil displacement efficiency and the residual oilsaturation have a turning point, the capillary value of this turning point is a critical value,when the capillary number is greater than this value, the oil displacement efficiency increasessignificantly. When the capillary number reaches the critical value, this change begins to slowdown. When the capillary number is invariant of different system, displacement efficiencyincreases apparently when the elasticity increases, which shows the impact of elasticity on oildisplacement efficiency is also very important. in the binary system we used in ourexperiment, the effect of interfacial tension, the apparent viscosity, viscoelasticity on oildisplacement efficiency is also discussed.