Development of Microorganisms with Improved Transport and Biosurfactant Activity for Enhanced Oil Recovery

We conducted a push-pull test to study in-situ biosurfactant production byexogenous biosurfactant producers to aid in oil recovery from depleted reservoirs. Fivewells from the same formation were used. Two wells received cells and nutrients, twowells were treated with nutrients only, and one well was used as the negative controlwhere only brine was injected. We hypothesized that the wells receiving nutrients andcells treatment would be able to produce biosurfactant in-situ compared to nutrient only–treated wells or the negative control. After incubation and a shut-in period to allow in situgrowth and metabolism, a series of chemical, microbiological, and molecular analyseswere conducted on the produced fluids to obtain evidence for growth, metabolism, andbiosurfactant production. Results showed that the wells treated with cells and nutrientsindeed produced biosurfactant compared to the other wells as evidenced by the increasein surface activity. Lipopeptide biosurfactants of concentration up to 350 ppm weredetected. This is an order of magnitude higher than the CMC. Evidences for substrateutilization and metabolism were detected in the wells treated with cells and nutrientswhere % carbon recovery was 124%, and 116%. Acids as acetate, formate, and lactate,and solvents as ethanol, and 2,3 butanediol were detected in the inoculated wells. MPNanalysis of influents and effluents of the treated wells showed a ratio of 2.2 and 1.2 forthe number of biosurfactant producers and a ratio of 654 and 1727 for the total number ofcells in the produced fluids compared to the injection fluids of inoculated wells. For thefirst time, we show that biosurfactants were produced in-situ using simple nutrients atconcentrations that are sufficient to mobilize significant amounts of residual oil. Second,inoculation of oil wells with exogenous biosurfactant-producers was possible. These twofindings support the efficacy of the use of biosurfactants to recover entrapped oil.