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A model study of enhanced oil recovery by flooding with aqueous surfactant solution and comparison with theory

Fletcher, Paul D. I.; Savory, Luke D.; Woods, Freya; Clarke, Andrew; Howe, Andrew M.

Authors

Paul D. I. Fletcher

Luke D. Savory

Freya Woods

Andrew Clarke

Andrew M. Howe

Abstract

With the aim of elucidating the details of enhanced oil recovery by surfactant solution flooding, we have determined the detailed behavior of model systems consisting of a packed column of calcium carbonate particles as the porous rock, n-decane as the trapped oil, and aqueous solutions of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The AOT concentration was varied from zero to above the critical aggregation concentration (cac). The salt content of the aqueous solutions was varied to give systems of widely different, post-cac oil–water interfacial tensions. The systems were characterized in detail by measuring the permeability behavior of the packed columns, the adsorption isotherms of AOT from the water to the oil–water interface and to the water–calcium carbonate interface, and oil–water–calcium carbonate contact angles. Measurements of the percent oil recovery by pumping surfactant solutions into calcium carbonate-packed columns initially filled with oil were analyzed in terms of the characterization results. We show that the measured contact angles as a function of AOT concentration are in reasonable agreement with those calculated from values of the surface energy of the calcium carbonate–air surface plus the measured adsorption isotherms. Surfactant adsorption onto the calcium carbonate–water interface causes depletion of its aqueous-phase concentration, and we derive equations which enable the concentration of nonadsorbed surfactant within the packed column to be estimated from measured parameters. The percent oil recovery as a function of the surfactant concentration is determined solely by the oil–water–calcium carbonate contact angle for nonadsorbed surfactant concentrations less than the cac. For surfactant concentrations greater than the cac, additional oil removal occurs by a combination of solubilization and emulsification plus oil mobilization due to the low oil–water interfacial tension and a pumping pressure increase.

Journal Article Type Article
Publication Date Mar 17, 2015
Journal Langmuir
Print ISSN 0743-7463
Electronic ISSN 1520-5827
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 31
Issue 10
Pages 3076-3085
Institution Citation Fletcher, P. D. I., Savory, L. D., Woods, F., Clarke, A., & Howe, A. M. (2015). A model study of enhanced oil recovery by flooding with aqueous surfactant solution and comparison with theory. Langmuir : the ACS journal of surfaces and colloids, 31(10), 3076-3085. doi:10.1021/la5049612
DOI https://doi.org/10.1021/la5049612
Keywords Spectroscopy; Electrochemistry; General Materials Science; Surfaces and Interfaces; Condensed Matter Physics
Publisher URL http://pubs.acs.org/doi/abs/10.1021/la5049612
Additional Information This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/la5049612

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