Evaluation of ionic effect of green surfactants on interfacial tension reduction under reservoir conditions for enhanced oil recovery
Ions play a vital role in surfactant chemistry of EOR. The ionic effects of green surfactants are not yet well characterised, but they are biodegradable and environmental friendly, and have great potential for EOR. This study characterises some green anionic and non-ionic surfactants through the determination of the interfacial tension (IFT) of each group and the combined effect of the green surfactants with alcohols on IFT and micro emulsions; and the oil recovery factor through laboratory experiments. Alky Polyglucosides (APG) was selected from the non-ionic group, which can produce ultra low IFT. APG surfactants are produced from coconut/palm oil, corn, potato or wheat residues. Bio-surfactants produced by a microbe called Bacillus mojavensis was taken from the anionic group. This study has found that the APG surfactants are completely and quickly biodegradable and environmentally friendly. APG surfactants show low long-term aquatic toxicity for bacteria, favourable for fish and acceptable effects are on Daphnia and Algae. Our laboratory tests have confirmed that APG PG 8166 can reduce IFT from 12–3.16 dyne/cm at 40 ppm under laboratory ambient condition and from 12–4.32 dyne/cm at a reservoir condition of 50oC and 1000psi. In contrast, the bio-surfactant at 40 ppm decreased IFT from 12–4.14 dyne/cm at the same reservoir condition. Temperature appears to have little effect on the IFT of APG surfactants. There is no significant reduction in the IFT values when APG at 10 ppm combined with the pentanol at concentrations of 15–120 ppm.