Low Salinity Polymer Flooding

Low salinity waterflooding has received increasing attention. However, the increased oil recovery by low salinity is in most cases very limited. Combining low salinity with other EOR methods has been our focus in recent years. The combined effect of brine chemistry and added surfactant on oil recovery was addressed by Alagic and Skauge in recent publications. Their results show incremental recoveries of 20-30% OOIP from low salinity surfactant (LS-S) injection. The low salinity surfactant solutions used showed type II- phase behaviour with the crude oil used in the tests. We have in this study made core flood experiments to study the combined effect of low salinity and polymer injection. The polymer used is HPAM and the concentration of polymer has been very low. The change in injection brine viscosity is therefore very small, but the impact on oil recovery is significant. The results also show the benefit of secondary low salinity flooding in combination with polymer injection compared to tertiary injection.