Microbial Enhance Oil Recovery (MEOR) is a relatively economical method to recover residual oil, but it is difficult to identify optimal conditions for microbe growth rate, activity, or quantity of favourable by-products in the varying conditions of different reservoirs. Many aerobic microorganisms can produce bio-surfactants which are capable of effectively reducing interfacial tensions (IFT) between oil, formation water and the rock matrix. Presently there are few publications on the production of bio-surfactants from anaerobic organisms. Moreover, most of the previous studies deal with single by-product of microbes and single process. The combined effect of bio-surfactant and bio-alcohol, and bio-surfactant, green surfactant and alcohol in the MEOR process, are not well understood yet and require further investigation. This study was conducted to examine the effectiveness of combination of two microbial by-products, bio-surfactant and bio-alcohol, in recovering residual oil within the pores of rock. It also considered whether biosurfactant capability could be improved by blending it with non-ionic green surfactant. The study consisted of laboratory experiments and simulations.
Three formulations of surfactant and co-surfactant mixtures were selected for coreflood experiments based on phase behaviour study and IFT reduction to examine their potential for enhanced oil recovery (EOR). In the first formulation, JF-2 biosurfactant was mixed with butanol; it was found that this formulation did not produce a significant quantity of incremental oil (about 1.7% of oil initially in place [OIIP]) after water flooding. This formulation did not perform as expected. In the next formulation, a blend of APG 264 and butanol showed good oil recovery results in a core-flood experiment, with 82% of OIIP recovered. Lastly, a bio-surfactant (anionic) was blended with non-ionic green surfactant alkyl polyglucoside (APG) and butanol; this produced about 25% tertiary oil and 64% OIIP.
A commercial Eclipse simulator was modified to add the option to simulate a MEOR process as this was not available. The modified simulator was used to simulate three core-flood experiments with three formulations. The JF-2 bio-surfactant and butanol solution core-flood test was simulated. The result was slightly higher than the experimental result but compared reasonably well. The simulated tertiary and total oil recoveries of the APG and Butanol solution were similar to the experimental values: the simulated TOR and total recovery were 41% and 81% respectively, while the core-flooding TOR and total recovery were 41% and 82%. The APG, biosurfactant and butanol combination core-flood experiment, when simulated, produced an oil recovery curve that was a good match with the experimental curve.
Based on the laboratory and simulation studies, a new method of Green Enhanced Oil Recovery (GEOR) was developed, and its potential for use in Australian oil fields was examined. It was found that this method is applicable to many oil fields, depending on salinity and reservoir temperature. It may also be used in place of MEOR if this is proving slow or inefficient.
|Qualification||Doctor of Philosophy|
|Publication status||Unpublished - 2012|