The objectives of the project are 1) to develop microbial strains with improved biosurfactant properties that use cost-effective nutrients, 2) to obtain biosurfactant strains with improved transport properties through sandstones, and 3) to determine the empirical relationship between surfactant concentration and interfacial tension (IFT).

Program
One goal of the Development of Technologies and Capabilities for Developing Coal, Oil and Gas Energy Resources, Solicitation DE-PS26-01NT41048, was to develop cost-effective gas, chemical, or microbial flooding methods to slow the rate of decline in domestic crude oil production.

University of Oklahoma
Norman, OK

Arrow Oil and Gas, Inc.
Norman, OK

Surbec-Art Environmental
Norman, OK

While microbial processes hold great promise for EOR, hurdles preventing implementation of MEOR include inconsistent performance, low ultimate oil recovery factor, and uncertainty over whether microbial processes meet engineering design criteria. This is certainly the case for biosurfactant-effected oil recovery where oil recovery is lower than for chemical surfactants and it is uncertain whether sufficient amounts of biosurfactant can be made in situ. Researchers have shown that the lipopeptide biosurfactant produced by Bacillus mojavensis strain JF-2 can reduce the IFT between oleic and aqueous mixtures to very low levels. These large reductions in IFT should result in substantial recovery of residual oil. However, laboratory experiments using this strain or other microorganisms often give inconsistent results. Researchers improved transport and biosurfactant production properties of bacterial strains to solve these technical difficulties.

Project Results
Project researchers found that 1) diverse microorganisms produce biosurfactants, 2) nutrient manipulation may provide a mechanism to increase biosurfactant activity, 3) spore transport occurs at high efficiencies, 4) biosurfactant concentrations in excess of the critical micelle concentration recover substantial amounts of residual oil, and 5) equations that describe the effect of the biosurfactant on IFT adequately predict residual oil recovery in sandstone cores.

Benefits
The long-term economic potential for enhanced oil recovery (EOR) is large, with more than 300 billion barrels of oil remaining in domestic reservoirs after conventional technologies reach their economic limit. The U.S. DOE Reservoir Data Base contains listings for more than 600 reservoirs with over 12 billion barrels of currently unrecoverable oil that are potential targets for microbially enhanced oil recovery (MEOR). If MEOR could be successfully applied to reduce residual oil saturation by 10% in a fourth of these reservoirs, more than 300 million barrels of oil could be added to U.S. oil reserves. This would stimulate oil production from domestic reservoirs and reduce the Nation's dependence on foreign imports.

Project Summary
The project generated these findings:

• Diverse microorganisms produce biosurfactants. Researchers found that 70% of the 205 strains tested produced biosurfactants at elevated salt concentrations and that some strains maintained this activity over a 14-day period.
• The activity of lipopeptide biosurfactants depends on the ratio of branched-chain to straight-chain fatty acids in the molecule. A multiple regression model accurately predicted the specific biosurfactant activity of 4 new biosurfactants using this ratio.
• Nutrient manipulation may provide a mechanism to increase biosurfactant activity. Researchers identified a novel growth requirement, deoxyribonuclosides, which allows luxurious growth of biosurfactant-producing bacteria in the absence of air. The specific activity of the biosurfactants can be enhanced by nutrient manipulation.
• Spores of Bacillus mojavensis strains JF-2 and ROB-2 and a natural recombinant strain C-9 transport through sand at very high efficiencies (almost complete recovery of the injected spores within 1-2 pore volumes). Project data show that use of spores for inocula in MEOR is practical.
• Biosurfactant concentrations in excess of the critical micelle concentration recover substantial amounts of residual oil. IFT decreased in a stepwise manner as biosurfactant concentration increased with marked reductions in IFT occurring at biosurfactant concentrations of 10 and 40 mg/l.
• A mathematical model that relates oil recovery to biosurfactant concentration was modified to include the stepwise changes in IFT as biosurfactant concentrations changes. This model adequately predicted the experimentally observed changes in IFT as a function of biosurfactant concentration.

The project is in a no-cost extension to allow completion of sampling after the microbial field test. All other tasks were completed on schedule.

Publications
Maudgalya, S., Folmsbee, M.M., Knapp, R.M., Nagle, D.P., and McInerney, M.J., Significant mobilization of entrapped hydrocarbon using biosurfactants with viscosity control and low molecular weight alcohol. Second International Conference of Petroleum Biotechnology, November 5-7, Instituto Mexicano del Petróleo, Mexico City, Mexico, 7 2003.

Maudgalya, S., McInerney, M.J., Knapp, R.M., Nagle, D.P., and Folmsbee, M.J., Development of biosurfactant-based microbial enhanced oil recovery procedure, SPE 89473, SPE/DOE Fourteenth Symposium on Improved Oil Recovery, Tulsa, OK, April, 17-21, 2004.

Youssef, N.H., Duncan, K.E., Nagle, D.P., Savage, K.N., Knapp, R.M., and M. J. McInerney. 2004. Comparison of methods to detect biosurfactant production by diverse microorganisms. J. Microbiol. Meth. 56: 339-347.

Folmsbee, M., McInerney, M.J., and Nagle, D.P., Anaerobic growth of Bacillus mojavensis JF-2 and three other Bacillus strains requires deoxyribonucleotides or DNA. Appli. Environ. Microbiol. 70: 5252-5257, Nov. ASM issue, 2004.

McInerney, M.J., Nagle, D.P., and Knapp, R.M., Microbially enhanced oil recovery: past, present, and future, pp. 215-237. In: Magot, M., and Ollivier, B., Petroleum Microbiology, American Society for Microbiology Press, Washington, D.C., 2005.

Maudgalya, S., McInerney, M.J., Knapp, R.M., Nagle, D.P., and Folmsbee, M.J., Tertiary oil recovery with microbial biosurfactant treatment of low-permeability Berea sandstone cores. SPE 94213, 2005 SPE Production and Operations Symposium, Oklahoma City, OK, April 17-19, 2005.

$738,805

$274,197 (27% of total)

NETL - Virginia Weyland (virginia.weyland@netl.doe.gov or 918-699-2041)
U. of Oklahoma - Michael J. McInerney (mcinerney@ou.edu or 405-325-6050)