Selecting An Optimum Hydrophobic Groups From Vegetable Oil Derivative for Surfactants used in Enhanced Oil Recovery

The need for fossil fuels which tends to increase without an increase in oil production has become the main factor in applying the Enhanced Oil Recovery (EOR) methods in the mature oil field. Chemical injection using surfactants is one of the EOR technologies that has been proved to be able to increase oil recovery. In this study, surfactants were synthesized using a fatty acid derived from palm oil as hydrophobic group and polyethylene-glycol as hydrophilic group. The use of vegetable oil as raw material is possible because it is abundant and environmentally friendly. Esterification of nonionic surfactant was performed by utilizing the azeotrope technique (Toluena-H2O) between fatty acid (oleic, stearic, palmitic and lauric acids) and polyethylene glycol (PEG) (200, 300, 400, 600, 1000, and 1500). The reaction was optimized with various moles of fatty acid and PEG equivalents (1:1,1; 1:2,5; 1;3) and various time reaction. Product surfactant was characterized by thin-layer chromatography (TLC) to determine the optimum condition and reaction conversion. The molecular structure of the surfactant was confirmed by 1H NMR. Nonionic surfactant was then analyzed by measuring the interfacial tension (IFT) of oil and water. The results showed that the optimum conditions to obtain the lowest IFT were achieved by reacting hydrophobic groups of oleic acid and hydrophilic groups of PEG-400 at an equivalent mole ratio of 1: 3 and a reaction time of 5 hours. Oleic PEG-400 surfactant was able to decrease the IFT of oil and water as low as 10-4 dyne/cm in brine salinity condition of 18000 ppm and oil 34,39 OAPI. The results was then used to design the synthesis of vegetable surfactant oil with various carbon chain lengths and functional groups as an EOR surfactant hydrophobic group.