The potential of Bacillus licheniformis strains for in situ enhanced oil recovery

Ability of indigenous Bacillus licheniformis and Bacillus subtilis in microbial enhanced oil recovery

“…Higher NaCl concentration in the medium did not affect the ability of the isolated bacteria in the reduction of surface tension considerably. The isolated strains behaved like the studies of Yakimov and Amro (1997). They reported that isolation of strain of Bacillus licheniformis from a petroleum reservoir was able to produce surfactant oprimally at 6 % NaCl concentration (Banat, 1993).…”

Development of an In Situ Biosurfactant Production Technology for Enhanced Oil Recovery

“…However, there are several biosurfactants that generate the low interfacial tensions between the hydrocarbon and the aqueous phases required to mobilize entrapped hydrocarbon [21,[67][68][69]. In particular, the lipopeptide biosurfactant produced by Bacillus species [21,34,36,38,39,70,71] and the rhamnolipid produced by various Pseudomonas species [59] reduce the interfacial tension between the hydrocarbon and aqueous phases to very low levels (<0.01 mN/m) [22,67,69]. In addition, the critical micelle concentrations are low (20-50 mg/l), indicating that the biosurfactants are effective at very low concentrations [67].…”

“…However, the number of pore volumes required (40 to 70) was large. Residual oil is recovered when a biosurfactant-producing bacterium and the nutrients needed to support growth are introduced into sandstone cores [38,77,78], but residual hydrocarbon recoveries were often low (5 to 20%) and required multiple pore volumes of recovery fluid.…”

“…Approximately 82% of the residual hydrocarbon in sand-packed columns was recovered when less than one pore volume of culture fluid containing about 900 mg/l of the biosurfactant was injected into the column. [36,38,39] and, in one case, residual oil recoveries up to 39% were reported [34]. In addition to the biosurfactant, a small molecular weight alcohol (2,3-butanediol) and a polymer were required [43].…”

“…The most successful MEOR process by Brown With such a promising outlook for biosurfactant flooding, one must ask the question why the technology has not been implemented more extensively. The results of several laboratory studies show that residual oil recoveries by biosurfactant-producing microorganisms are low and inconsistent [34][35][36][37][38][39]. There are several potential reasons for this including the inconsistent production of the biosurfactant, loss of biosurfactant activity with extended incubation, and nutrient limitations that delay the growth of the requisite microorganisms.…”