Use of Biosurfactants in Oil Recovery

Abstract

Biosurfactant-mediated oil recovery has the potential to recover large amounts of crude oil that remain entrapped in oil reservoirs after current oil recovery technologies reach their economic limit. Lipopeptides (surfactins and lichenysins), rhamnolipids, and other glycolipids generate the low interfacial tensions and the appropriate rock wettabilities needed to mobilize entrapped oil. Biosurfactants are active over a wide range of temperatures, pH values, and salinities found in many oil reservoirs and are effective at low concentrations. A number of laboratory experiments show that biosurfactant-mediated oil recovery is effective in recovering large amounts of entrapped oil. Several field trials show that in situ

Effects of Air Injection on the Metabolic Activity of Emulsifier-Producing Bacteria from Oil Reservoirs

“…The results of surface tension measurements indicate that the emulsification of crude oil in cultures may be at least partially dependent on the production of emulsifiers because the surface tension of cultures will be lower than 40 mM/m if small-molecule biosurfactants contribute to the emulsification of crude oil [16]. Although the emulsification of crude oil in the aerobic culture and the intermittent aeration culture appeared to be similar, the droplet size and uniformity of emulsified oil in the aerobic culture were clearly superior to those in the intermittent aeration culture (Figure 3).…”

“…Existing biosurfactants mainly include glycolipids (rhamnolipids, sophorolipids, and trehalolipids), lipopeptides (surfactins, lichenysins), some proteins, and bioemulsifiers [14,15]. Small-molecule surfactants can not only reduce oil/water interfacial tension but also emulsify crude oil, while macromolecular emulsifiers have better emulsifying ability and emulsion stability [16]. Biosurfactant-producing microbes mainly include Acinetobacter, Alcaligenes, Bacillus, Enterobacter, Pseudomonas, and Rhodococcus, together with some strains in the genus Serratia, most of which are strictly aerobic bacteria [16,17].…”

“…Small-molecule surfactants can not only reduce oil/water interfacial tension but also emulsify crude oil, while macromolecular emulsifiers have better emulsifying ability and emulsion stability [16]. Biosurfactant-producing microbes mainly include Acinetobacter, Alcaligenes, Bacillus, Enterobacter, Pseudomonas, and Rhodococcus, together with some strains in the genus Serratia, most of which are strictly aerobic bacteria [16,17]. Therefore, the injection of air during the microbial flooding process is essential for activating surfactant-producing bacteria.…”