Biosurfactant, especially the microbially derived surfactant, is essential for the recovery and production of petroleum from oil reservoirs. The spiculisporic acid (S-acid) can be easily obtained from a fungus, Penicillium spiculisporum by aerobic cultivation. It was especially found that a great number of n-alkylamine salts can be formed with the S-acid. The chain of the alkylamine moiety can be adjusted for a desirable interfacial tension. The use of the hydrophilic-hydrophobic balance (HLB) is illustrated. It is possible to develop a suitable in-situ surfactant for a specific application in any porous medium by an above-the-ground fermentation with the appropriate reaction with an n-alkylamine. Because of the huge quantities of n-alkylamines available, the production of this type of surfactant should be cost-efficient. (C) 1998 Elsevier Science B.V. All rights reserved.
