Preliminary Evaluation of Amphiphilic Block Polyelectrolytes as Potential Flooding Agents for Low Salinity Chemical Enhanced Oil Recovery

Amphiphilic block polyelectrolytes are known for their remarkable thickening properties in water solution, originating from their ability to self-assemble into large micellar aggregates. This makes them promising flooding agent for chemical enhanced oil recovery (cEOR). However, to the best of our knowledge, they have not yet been directly investigated for this purpose. In this work, a survey of relevant properties for EOR (rheology, filterability and emulsification), and laboratory scale oil recovery experiments, were performed on water solutions of polystyrene-block-poly(methacrylic acid) amphiphilic block polyelectrolytes, and compared with a commercial partially hydrolyzed polyacrylamide (HPAM), to evaluate the real potential in EOR applications for the first time. It was found that the recovery of amphiphilic block copolymers in low salinity brine (0.2% concentration of NaCl) is remarkably higher than that of HPAM at comparable weight concentration and shear viscosity, despite a much lower molecular weight. Effect of salinity and emulsification properties of the studied polymers have also been preliminarily investigated. Our results suggest that the recovery mechanism of these polymers differs from the traditional mechanism of polymer flooding, possibly due to emulsification of the oil. In conclusion, the studied amphiphilic block polyelectrolytes show promise as chemical agents in low salinity polymer flooding.