Extraction of the indigenous crude oil dissolved biosurfactants and their potential in enhanced oil recovery

Abstract

The presence of indigenous microorganisms in the petroleum reservoirs with the capability of biosurfactants production implies the existence of significant amounts of biosurfactants dissolved in the reservoir crude oil. The extraction of these biosurfactants to the aqueous phase can be considered as a promising microbial enhanced oil recovery process in a lower cost without the common limitations and risks related to the microbial systems. Ethylenediamine (EDA) was used to extract the crude oil dissolved biosurfactants (as anionic surfactants) of a crude oil sample to the aqueous phase and form a cat-ionic surfactant complex. The biosurfactant was isolated from the crude oil and preliminarily characterized which was capable of reducing the surface tension to 48 mN/m. Various concentrations of EDA were utilized to extract the crude oil biosurfactants and their effectiveness on the oil recovery was studied in a glass micro-model. Results indicated that an incremental 22 % oil production was obtained by flooding the 10 mM EDA solution. The incremental oil production was related to the formation of the cat-ionic complex surfactant which believed to cause a significant IFT reduction and simultaneously, have a higher efficiency in the wettability alteration than the anionic biosurfactants. It can be concluded that the extraction of the indigenous biosurfactant content of the crude oil and their interaction by EDA can be considered as a low-cost low-risk potential to the enhanced oil recovery processes. © 2020 Elsevier B.V.