Thermo‐ and CO₂‐triggered swelling polymer microgels for reducing water‐cut during CO₂ flooding

Abstract

ABSTRACT CO 2 has been widely used in the process of enhanced oil recovery (EOR) over decades. However, the heterogeneity of oil reservoirs renders CO 2 to flow preferentially into highly permeable zones, leaving tight areas unswept with oil unrecovered in these areas. While conventional water‐swelling gels were used for blocking the “channeling” path, most of them experience the risks of shrinkage under high temperature and CO 2 ‐induced acidic environment. Here, we developed double swelling smart polymer microgels (SPMs) triggered by both heat and CO 2 . Such SPMs were prepared by copolymerization of acrylamide (AAm) in combination with N , N ‐2‐(dimethylamino)ethyl methacrylate (DMAEMA) and [2‐(methacryloyloxy) ethyl]dimethyl‐(3‐sulfopropyl) ammonium hydroxide (SBMA), and with N,N′ ‐methylene bisacrylamide (MBA) as the crosslinker. These SPMs swell when temperature is higher than 65 °C or in the presence of CO 2 , with an ameliorative salinity tolerance ability. Artificial sand pack flooding carried by SMPs at 65 °C showed an elevated plugging efficiency at around 97% under a simulated pressurization at 5 MPa, proposing a valid candidate for future EOR applications during CO 2 flooding. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 48305.