Perpustakaan Digital ITB

Residual oil trapped by capillary forces remains difficult to mobilize through conventional waterflooding, necessitating the application of an Enhanced Oil Recovery method to significantly reduce the interfacial tension (IFT) between the oil and aqueous phases. This study evaluates the performance of a zwitterionicanionic surfactant mixture, consisting of Macat-AO14 (MA-AO14) as the zwitterionic surfactant and Aristonate-M (AR-M) as the anionic surfactant, with isopropyl alcohol (IPA) at a concentration of 0.1% as a co-solvent, using crude oil from Field X. The experimental evaluation consisted of three sequential stages, namely aqueous stability tests, phase behavior observations, and IFT measurements using a spinning drop tensiometer. These tests were conducted across a NaCl salinity range of 0.5% to 2.5% and total surfactant concentrations of 0.15 wt% and 0.3 wt%. The results demonstrated that the MA-AO14/AR-M formulations at 70/30 and 80/20 ratios exhibited the best aqueous stability. Notably, the 70/30 ratio successfully formed a Winsor Type III middle-phase microemulsion and achieved an ultralow minimum IFT of 8.65 × 10?³ mN/m at an optimum salinity of 1.75% NaCl. Conversely, the 80/20 ratio failed to reach the ultralow IFT order. Furthermore, increasing the total surfactant concentration to 0.3 wt% yielded no significant improvement in IFT reduction. These findings indicate that the MA-AO14/AR-M at a ratio of 70/30, with a surfactant concentration of 0.15 wt%, a salinity of 1.75% NaCl and an IPA concentration of 0.1%, represents the best performing zwitterionic-anionic surfactant formulation under the evaluated conditions.