SPE Journal
Volume 16, Number 3, September 2011, pp. 672-682

SPE-129228-PA

Optimization and Partial Characterization of Biosurfactants Produced by Bacillus Species and Their Potential for Ex-Situ Enhanced Oil Recovery

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DOI  More information 10.2118/129228-PA http://dx.doi.org/10.2118/129228-PA

Citation

  • Al-Sulaimani, H., Al-Wahaibi, Y., Al-Bahry, S., Elshafie, A., Al-Bemani, A., Joshi, S., and Zargari, S. 2011. Optimization and Partial Characterization of Biosurfactants Produced by Bacillus Species and Their Potential for Ex-Situ Enhanced Oil Recovery. SPE J.  16 (3): 672-682. SPE-129228-PA. http://dx.doi.org/10.2118/129228-PA.

Discipline Categories

  • 6.4.8 Microbial Methods

Keywords

  • biosurfactant, MEOR, interfacial tension , Bacillus licheniformis

Summary

This study aims to test the potential of microbial enhanced oil recovery (MEOR) as an effective alternative in Omani oil fields. In this study, biosurfactants produced by Bacillus licheniformis and Bacillus subtilis strains isolated from oil-contaminated soils from different parts of the Sultanate of Oman were investigated. Eight different minimal production media using different sugars as carbon sources were tested on three of the strains to select the medium that maximized the production of biosurfactants which were indicated by the interfacial tension (IFT) reduction. All isolates were tested on their potential media to screen for the best biosurfactant producer among the available strains. It was found that Bacillus subtilis Strain W19 gave the maximum IFT reduction (46.6 mN/m to 3.28 mN/m) in 16 hours of incubation when grown in a minimal medium containing glucose. The yield of the biosurfactant produced by B. subtilis W19 was 2.5g/L. Critical micelle concentration (CMC) was measured to be 0.4 g/L. The biosurfactant was partially characterized by FT-IR analysis, in which the peaks obtained imply the presence of aliphatic hydrocarbons as well as a peptide-like moiety in the biosurfactant.

The cell-free biosurfactant broth produced from Strain W19 was found to be stable over a pH range from 6 to 10 and was most effective at 7. It also showed no loss in surface activity when subjected to various temperatures (60, 80, and 120°C). The biosurfactant also retained almost 60% of its activity even in a high-saline environment up to 20% NaCl (w/v).

Further studies were conducted to test the interaction of biosurfactant produced by B. subtilis W19 with porous media in coreflooding experiments as a tertiary-recovery stage. The results showed high potential of using this bacterium during ex-situ MEOR applications in which a total of 23% of residual oil was produced after biosurfactant and concentrated-biosurfactant injection.

© 2011. Society of Petroleum Engineers

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History

  • Original manuscript received: 1 March 2010
  • Meeting paper published: 12 April 2010
  • Revised manuscript received: 8 January 2011
  • Manuscript approved: 12 January 2011
  • Published online: 9 June 2011
  • Version of record: 15 September 2011