(44i) Surfactant–Polymer Flooding in Carbonate Using Novel Synthesized Zwitterionic Surfactant and Oilfield Polyacrylamide

After waterflooding process, an enhanced oil recovery (EOR) process is applied to increase oilfield recovery performance by improving sweep efficiency and/or pore-scale displacement in the reservoir. Nonetheless, conventional surfactant precipitates in high salinity and high temperature conditions. Herein, a novel synthesized zwitterionic surfactant with sterling salinity and thermal tolerance is commingled with oilfield polyacrylamide for surfactant–polymer flooding process at high-temperature and high-pressure conditions in carbonate core.

Hydroxybetaine zwitterionic surfactant was synthesized for this study. The synthesized surfactant was investigated for its efficiency at lowering interfacial tension (IFT) at the oil-water interface using a spinning drop tensiometer. Besides, the wettability behavior of the surfactant at the rock-fluid interface was investigated via contact angle measurement using a Biolin Scientific drop shape analyzer. Furthermore, the rheology of the surfactant with oilfield polyacrylamide was studied using an Anton Paar rheometer. Finally, an oil displacement test was carried out using high-temperature high-pressure core flooding equipment.

The novel synthesized surfactant was stable in high temperature and high salinity conditions and showed no sign of precipitation. Moreover, the surfactant demonstrated moderate efficiency at lowering the IFT of oil-water to 1.5 mN/m in the presence of seawater salinity and high temperature condition. Furthermore, the surfactant changes the wettability of the rock-fluid interface from oil-wet ( 165 ) to aqueous-wetting condition ( 50 ). The blend of the zwitterionic surfactant and oilfield polyacrylamide showed good compatibility in seawater salinity and exhibited pseudoplastic behavior at a high shear rate. The slug-wise injection of the surfactant–polymer flood at elevated temperature and pressure conditions yielded higher oil recovery over conventional waterflooding and polymer flooding process. The mechanism of the additional oil recovery recorded is elucidated.

Conventional surfactants precipitate at high salinity and high temperature conditions, thus inhibiting their effectiveness for EOR application. The novelty of this study is the application of novel hydrooxybetaine zwitterionic surfactant with oilfield polyacrylamide for high-salinity and high-temperature carbonate reservoirs.