Injection parameters optimization of cross-linked polymer microspheres and polymer composite flooding system

Based on the facts that there is no obvious improvement in injection conformance and no significant water cut reduction in production wells after polymer flooding in S oilfield in Bohai Bay, this study used cross-linked polymer microspheres-polymer composite flooding to research the effect of chemical system composition, displacement speed, injection volume on polymer flooding by physical simulation experiments, and to optimize injection parameters of composite system. The results showed that the higher the concentration of cross-linked polymer microspheres at a total concentration of 1750 mg/L, the more the oil recovery enhancement; the 1350− 1650 mg/L polymer composite system can achieve better oil recovery when the cross-linked polymer microsphere concentration reaches 400−100 mg/L; compared with single polymer flooding, the cross-linked polymer microspheres and polymer composite system flooding can enhance recovery factor by 8%−11%; in addition, it was found that the composite system could better improve polymer flooding at the displacement rate of 3.5 m/d and the injection volume of 530 mg/L?PV. Key words: cross-linked polymer microspheres, polymer, composite displacement system, injection parameter, deep displacement, offshore oilfiel