Abstract
The biosurfactant production by Bacillus licheniformis W16 and evaluation of biosurfactant based enhanced oil recovery (EOR) using core-flood under reservoir conditions were investigated. Previously reported nine different production media were screened for biosurfactant production, and two were further optimized with different carbon sources (glucose, sucrose, starch, cane molasses, or date molasses), as well as the strain was screened for biosurfactant production during the growth in different media. The biosurfactant reduced the surface tension and interfacial tension to 24.33 ± 0.57 mN m−1 and 2.47 ± 0.32 mN m−1 respectively within 72 h, at 40°C, and also altered the wettability of a hydrophobic surface by changing the contact angle from 55.67 ± 1.6 to 19.54°± 0.96°. The critical micelle dilution values of 4X were observed. The biosurfactants were characterized by different analytical techniques and identified as lipopeptide, similar to lichenysin-A. The biosurfactant was stable over wide range of extreme environmental conditions. The core flood experiments showed that the biosurfactant was able to enhance the oil recovery by 24–26% over residual oil saturation (Sor). The results highlight the potential application of lipopeptide biosurfactant in wettability alteration and microbial EOR processes.
Highlights
Recent updates in our understanding of the microbial metabolisms and their biochemical pathways lead to different applications in petroleum industries like enhancing oil recovery, biodegradation of oil-based waste, treatment of oil-field produced water, bioremediation of oil-spills, etc
Several of the bacterial products are reported for playing a role in microbial enhanced oil recovery (MEOR), where biopolymers and biosurfactants are reported as key players (Belyaev et al, 2004; Sen, 2008; Marchant and Banat, 2012a)
Amongst different kind of biosurfactants, low molecular compounds – lipopeptides produced by sporeforming bacteria are regarded as having potential role in MEOR
Summary
Recent updates in our understanding of the microbial metabolisms and their biochemical pathways lead to different applications in petroleum industries like enhancing oil recovery, biodegradation of oil-based waste, treatment of oil-field produced water, bioremediation of oil-spills, etc. Recently the trend has been shifted toward applications of green-compounds or bio-products, mainly because of the environmental concerns Biosurfactants are such biologically produced surfactants by microorganisms, plants, and animals. Several companies around the globe (UK, USA, Japan, Germany, China) are producing different types of biosurfactant (such as rhamnolipids, lipopeptides, sophorolipids, etc.), with focus on different applications (such as pharmaceuticals, cosmetics, antimicrobials and anticancer, bioremediation, EOR, etc.) (Sekon and Rahman, 2014). Even with all these new developments and increased interest by prominent business-houses, the economically availability and wide-spread applications of biosurfactants are still limited in petroleum industries. Surfactins and lichenysins produced by Bacillus subtilis and Bacillus licheniformis strains are reported for their high surface activities and other beneficial properties suitable for several applications like enhancing oil recovery (Jean-Marc et al, 2003)
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