(252h) Hydroxybetaine Zwitterionic Surfactants for Enhanced Oil Recovery: Compatibility with Acrylamide-based Copolymers and Rheological Properties

Oil is extracted from a reservoir in a three-stage process. During the initial and secondary stages, oil is extracted through the reservoir's natural pressure or by water injection, but this method only recovers 10% to 25% of the total oil present. Therefore, tertiary or enhanced oil recovery (EOR) methods are used to retrieve the remaining oil. Chemical methods are used in EOR, where various chemicals such as surfactants, polymers, and alkalis are injected to increase hydrocarbon recovery. Polymers are utilized to increase water viscosity, improving the oil/water mobility ratio, whereas surfactants are utilized to alter the interfacial tension between water and oil. In most cases, surfactants and polymers are injected together to achieve better mobility and lower interfacial tension, which is a challenging task due to harsh reservoir conditions. The research work under discussion synthesized polymeric hydroxybetaine zwitterionic surfactants, which were used with acrylamide-based copolymers that are thermally stable and salt-tolerant. The rheological properties of the surfactant with copolymer were analyzed using an Anton Paar rheometer, indicating compatibility at high temperatures with no precipitation. The surfactant reduced the interfacial tension between oil and water and demonstrated stable rheological properties with a stable viscosity profile over several days. The elastic modulus was also stable. The viscosity of the polymer decreased with the addition of surfactant in deionized water due to charge screening, but the viscosity of the polymer remained unaffected in seawater. The oil recovery experiments using the developed surfactant polymer system showed more than 15% oil recovery.