Perpustakaan Digital ITB

This study evaluates the effect of ionic composition on the performance of a 50:50 blend of Linear Alkylbenzene Sulfonate (LABS) and Sulfonated di-Alkyl Ester (SAE-2) anionic surfactants at a total concentration of 0.5 wt% for Chemical Enhanced Oil Recovery. Synthetic brines containing carbonate, bicarbonate, and sulfate salts with Na?, K?, Mg²?, and Ca²? were examined through interfacial tension measurements, phase-behavior analysis, aqueous-stability testing, and spontaneous imbibition using Berea sandstone cores at 65.5 °C. Field Y crude oil had an API gravity of 19.3°API, a viscosity of 8.49 cP, and a Total Acid Number of 0.284 mg KOH/g. The minimum IFT of 6.085 × 10?³ mN/m was achieved by the Na?SO? + MgSO? formulation. However, all samples remained within the Winsor Type I region, indicating that the tested salinity range was insufficient to form a Winsor Type III microemulsion. Selected formulations remained clear and homogeneous during seven days of static stability testing. The Na?SO? + MgSO? formulation also produced the highest recovery factor of 42.09%, compared with 4.58% for the base design. These results confirm that surfactant performance depends on ion type, concentration, electrostatic screening, hydration, and possible rock and fluid interactions. Further dynamic testing is required before practical reservoir-scale implementation and validation.