Critical micelle concentration, interfacial tension and wettability alteration study on the surface of paraffin oil-wet sandstone using saponin

Nowadays, the implementation of chemical enhanced oil recovery (CEOR) techniques improves the oil recovery by injecting synthetic surfactants in reservoir. However, the recent use of this synthetic surfactant is quite expensive and possesses toxicity problems when exposed to the environment. This issue has forced the search for alternative, cheaper and natural synthetic surfactant to enhance oil recovery. Hence, this study aims to provide some insights into the effect of saponin as natural plant-based non-ionic surfactant on the surface of paraffin oil-wet sandstone. The effectiveness of saponin depends on the critical micelle concentration (CMC), interfacial tension (IFT) and wettability alteration. The surfactant concentration containing saponin was varying from 0.005wt% to 0.07wt% to determine CMC value using surface tension measurement, meanwhile for IFT measurement was conducted at 0.5wt% to 8wt% concentration using Krus Tensiometer K6. The experiments were conducted at standard condition with 25°C and 14.7psia. The findings showed that surface tension for CMC value of saponin is 0.05wt%. Approximately 27% reduction from initial IFT was achieved with 8wt% of saponin concentration. The saponin successfully alter the wetting state of oil-wet sandstone to intermediate-wet through quantitatively measurement of contact angle. Saponin with low CMC value is favourable to become a reference concentration as natural surfactant, effective to alter of reservoir rock properties, facilitate oil mobilization, increase oil recovery and suggested as an additive for mitigating wax deposition.