Abstract
The effectiveness of a bio-surfactant-based microbial enhanced oil recovery process was studied. A series of laboratory experiments showed that bio-surfactant produced by the bacterium Bacillus mojavensis JF-2 mobilized and recovered residual oil when mixed with a co-surfactant, 2,3-butanediol and partially hydrolyzed polyacrylamide (PHPA) and flooded through sand packs at waterflood residual oil saturation. Twenty to eighty percent of the residual oil was recovered depending on the bio-surfactant concentration. The recovery was linearly dependent on bio-surfactant concentration.
The injection of a viscous solution ahead of the surfactant solution and a viscous mobility buffer behind the surfactant solution increased oil recoveries compared to treatments when only the surfactant was injected. With very low bio-surfactant concentrations, 16 ppm (0.0016% by wt.), 22% of residual oil was recovered when combined with 2, 3-butanediol and PHPA. The bio-surfactant without co-surfactant and/or viscosifying polymer recovered very little residual oil (<5.0%) even at very high bio-surfactant concentrations, (12,300 ppm).
The results showed that microbially generated surface active agents were effective for enhanced oil recovery even at low concentrations (0.0016%) as long as a viscosifying agent and a low molecular weight alcohol were present.
