SmartWater synergy with chemical EOR: Effects on polymer injectivity, retention and acceleration

The synergy between various enhanced oil recovery (EOR) processes has always been raised as a potential optimization route for achieving a more economic and effective EOR application. In previous work, beside the established positive impact of SmartWater on polymer rheology, we have demonstrated polymer positive impact on SmartWater effects through measurements of surface potential and contact angles. The results were also supported by forced oil-displacement experiments. In this work, we further investigate this SmartWater/Polymer synergy focusing on the possible impact of SmartWater on polymer floods specifically polymer injectivity, retention and acceleration. For this purpose, a set of thoroughly designed single-phase displacement experiments were performed at reservoir conditions. Many of the observed effects of SmartWater on polymer injectivity and transport can be attributed to polymer coil expansion in the lower-salinity SmartWater. The results mainly demonstrate that SmartWater has: (1) a slight negative impact on both polymer and chase water injectivity, (2) a positive impact on polymer retention, and (3) a negligible impact on polymer, hence oil bank, acceleration. Given the minor negative impact on injectivity, we conclude that SmartWater/Polymer flooding exhibits an overall favorable synergy that reduces chemical consumption, improves sweep, and enhance recovery.