Perpustakaan Digital ITB

Waxy crude oils present significant recovery challenges due to long-chain paraffins that generate strong interfacial cohesion and elevated oil-brine interfacial tension (IFT), exacerbating capillary trapping severity and residual oil saturation. This study investigates salinity and alkalinity effects on IFT reduction using linear alkylbenzene sulfonate (LAS) and alpha-olefin sulfonate (AOS) surfactants with a high-wax-content crude oil. Interfacial tension measurements were conducted at 60 °C using a spinning drop tensiometer across three experimental stages: NaCl salinity scan (2,500-12,500 ppm), NaHCO3 alkaline scan (1,000- 5,000 ppm), and binary LAS:AOS blend evaluation. LAS achieved minimum IFT of 0.826 mN/m at 5,000 ppm NaCl due to superior structural compatibility with paraffinic oil, while AOS showed gradual decrease to 1.074 mN/m at 12,000 ppm without distinct optimum. NaHCO3 demonstrated significant efficacy at initial dosing, reducing LAS IFT by approximately 49% through ionic strength enhancement and pH modification, before saturation near 3,000 ppm. The optimal result of 0.436 mN/m was achieved with a LAS-dominant 3:1 blend containing 2,000 ppm NaHCO3 and 10,000 ppm NaCl, demonstrating synergistic effects. Although LAS consistently outperformed AOS, none of the formulations achieved ultra-low IFT (<0.01 mN/m) required for complete oil mobilization. These findings indicate that a LAS-dominant blend combined with stronger alkaline (Na2CO3 or NaOH) should be investigated to achieve the capillary number enhancement necessary for effective waxy oil recovery.