The Comparison of Surfactant from Palm Oil and Stearic Acid to Improve Thermal Stability

Abstract

The most efficient enhanced oil recovery (EOR) method is chemical EOR (CEOR) using surfactants. Indonesia has successfully produced biodegradable surfactants from palm oil; however, these surfactants have the disadvantage of being less stable at high temperatures (above 60°C). The aim of this research is to improve the thermal stability of surfactants by selecting raw materials that have higher saturated fatty acid content, thus preventing the surfactants from easily degrading at high temperatures. The synthesized surfactants were characterized using various analytical methods, including FTIR, EDX, IFT, and TGA. The results of FTIR analysis indicated the presence of sulfonate groups in the 1160-1120 cm-¹ range, while EDX analysis confirmed the presence of elemental sulfur, indicating that the sulfonation process was successful. IFT analysis revealed that the palm oil-based surfactant (surfactant 1) had a lower IFT value than the stearic acid-based surfactant (surfactant 2). The IFT values obtained at concentrations of 0.1; 0.5 and 1% were 4.9 × 10-2; 4.3 × 10-2 and 2.8 × 10-2 dyne/cm for surfactant 1 and for surfactant 2 were 5.8 × 10-2; 5.4 × 10-2 and 4.5 × 10-2 dyne/cm, respectively. To assess their thermal stability, TGA analysis was performed, which showed that both surfactants have resistance to temperatures above the reservoir temperature. However, the stearic acid-based surfactants showed better thermal stability compared to the palm oil-based surfactants. The specific conditions of the reservoir and the needs of a particular application determine the selection between palm oil-based and stearic acid-based surfactants.