Hydrolysable preformed gels for conformance control in oilwells: Properties and degradation

Abstract

ABSTRACTConformance control using preformed gels (PGs) is an effective method to reduce water cut in production oilwells. However, PGs are unable to thicken formation of water, and the improvement of water‐oil mobility is limited. Compared with PGs, hydrolysable PGs (HPGs) with labile crosslinker incorporated could thicken the brine gradually. In this study, a series of HPGs were prepared based on labile crosslinker poly(ethylene glycol) diacrylate, self‐crosslinker N,N‐dimethylacrylamide (DMAM), and nanomaterial laponite. The long‐term thermal stability, swelling property, and thickening power of the HPGs were successively examined. It was demonstrated that DMAM remarkably improved the long‐term thermal stability of HPGs, and also imparted the swelling and thickening properties during aging period, while laponite effectively increased the viscosity of HPGs suspension but weakened the swelling ratio. Degradation monitored by nuclear magnetic resonance spectroscopy indicated that HPGs are decrosslinked gradually through the hydrolysis of labile crosslinker and then release a terpolymer of acrylamide, acrylate, and DMAM. The hybrid fluid containing the terpolymer and nanomaterial resulted in the increased viscosity of HPGs suspension. Artificial core flooding results showed that HPGs have good sealing capacity for conformance control, and incremental oil was recovered by using HPGs against traditional PGs with similar plugging efficiency owing to the increased viscosity of the HPGs dispersion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45413.