Characterization of comb polymer Kypam for enhanced oil recovery

The Chinese-produced comb polymer Kypam has been proposed for mobility control in oil reservoirs to improve volumetric sweep efficiency. Rheology experiments were conducted with the polymer to determine salt and polymer concentration effects. Viscosities of solutions prepared in SSW were sensitive to shear during mixing and with the addition of 1% KCl to the polymer solution a 74% reduction in viscosity was recorded. A concentration study determined that 3000 ppm Kypam in SSW met the target viscosity of 10 cp at 8 s -1.; Kypam solutions of known viscosity were injected into sand packs at a constant reservoir temperature of 60°C. The polymer mobilities varied with Darcy velocity from 260 md/cp at 2 ft/day to 340 md/cp at 15 ft/day. The polymer mobility constant, lambdap*, was determined to be 217 (md/cp)(ft/day)1-nc and the power flow constant, n c, 0.85. The polymer solutions exhibited a shear thinning behavior across this range of Darcy velocities. The polymer retention was calculated from a material balance and was determined to be 420 mug/g rock for unfiltered polymer solutions and 75 mug/g rock for filtered solutions.; In between polymer injections a viscosity reduction occurred in the polymer solutions that were shut-in the sand pack. Polymer concentrations for these shut-in effluent samples showed no decrease while the viscosities were greatly reduced. A partially hydrolyzed polyacrylamide polymer in the same SSW and experimental setup did not show this same behavior. The Kypam polymer exhibited this viscosity reduction when the silica concentration of the solution increased because of contact with the sand. Polymer solutions prepared with an already increased silica concentration exhibited 44% lower viscosities and did not undergo a further viscosity reduction when shut-in the sand pack at reservoir temperature.