Star-like hydrophobically associative polyacrylamide for enhanced oil recovery: Comprehensive properties in harsh reservoir conditions

This work fabricated a novel star-like hydrophobically associative polyacrylamide called SHPAM used in enhanced oil recovery (EOR) processes in harsh reservoir conditions. SHPAM composed of a core of nano-silica and a layer of amphiphilic-polymeric chains was synthesized via a facile water free radical polymerization. It was systematically characterized using TEM, SEM, IR, 1 H NMR and DLS. Measurements from solubility, thickening efficiency, long-term stability and rheological performance indicated that the three-dimensional microstructure and intermolecular associations provided SHPAM solution with fantastically comprehensive properties, outperforming hydrophobically associative polyacrylamide. The evidence from rectangle cores in a serial model experiments implied that SHPAM was well compatible with permeable cores and it had desirable injectivity with sustainable mobility control in porous media. Moreover, core flooding tests revealed that after extensive water flooding, SHPAM with the concentration of 1500 mg/L increased the oil recovery factor by 20% in sandstone cores. This study showed the robust potential of SHPAM as a polymer flooding candidate in high temperature and high salinity reservoirs where harsh conditions associated with lack of fresh water constrain the applications of conventional polymers.