<![CDATA[The increasing decline in oil production from mature reservoirs has encouraged the development of more effective and environmentally friendly Enhanced Oil Recovery (EOR) technologies. Surfactant flooding is a promising chemical EOR method because it can reduce interfacial tension, modify rock wettability, and mobilize trapped residual oil. This study aimed to evaluate the effectiveness of palm oil-based Methyl Ester Sulfonate (MES) surfactant in improving oil recovery through core flooding and spontaneous imbibition techniques. The experiment used Berea sandstone cores with approximately 21% porosity and 100 mD permeability, light crude oil with a gravity of 39°API, and two surfactant solution conditions: 5,000 ppm salinity with 0.5% MES concentration and 10,000 ppm salinity with 2% MES concentration. The results showed that the low-salinity MES solution provided better performance than the high-salinity condition. In the core flooding test, the 5,000 ppm salinity and 0.5% MES solution achieved the highest recovery factor of 84.74%, whereas the 10,000 ppm salinity and 2% MES solution achieved 62.63%. In the spontaneous imbibition test, the low-salinity condition resulted in 51.94% oil recovery, compared with 45.24% under high-salinity conditions. These findings indicate that lower salinity enhances surfactant stability, improves interfacial tension reduction, and promotes oil mobilization. Therefore, palm oil-based MES surfactant demonstrates strong potential as a sustainable chemical EOR agent for sandstone reservoirs.]]>
