The Effect of Changing Mobility Ratio on Displacement Efficiency in Polymer Flooding

Abstract

ABSTRACT The effect of changing mobility ratio on displacement efficiency in polymer flooding was investigated. For this purpose, experiments on unsteady-state displacement were conducted with two Berea sand cores of different permeabilities. Each core was flooded by displacing fluids of three different viscosity ratios. Relative permeability ratio curves measured on the core by changing the viscosity of displacing fluid, showed similar pattern in the same saturation path regardless of changing the viscosity of displacing fluid. Fractional flow curves measured on the core showed that higher viscosity of displacing fluid resulted in more efficient displacement; that is, as the viscosity of displacing fluid was increased, mobility ratio was decreased and displacement efficiency was increased. The effect of changing viscosity ratio on mobility ratio was considerably higher on low permeability core than on high permeability core. The displacement efficiency measured on low permeability core was higher than that of high permeability core by 26 percent at the time of breakthrough. It was shown from the experiment that polymer flooding would be applied more effectively in low permeability reservoirs.