Mechanistic understanding of chemical flooding in swelling porous media using a bio-based nonionic surfactant

A large quantity of world's oil reserves is stored in sandstone reservoirs where clay swelling phenomenon, owing to its negative impact on reservoir quality, imposes a challenge on applicability of surfactant flooding, a subset of chemical enhanced oil recovery (EOR). Therefore, surfactant flooding in swelling porous media should be carried out with more sensitivity. In this study, a great attempt was made to mechanistically understand the performance of a bio-based nonionic surfactant named Zizyphus Spina Christi leaf extract (ZSCLE) in EOR process from swelling porous media. This purpose was achieved through determination of linear swelling, viscosity, pore plugging index, oil recovery, zeta potential, particle size as well as FT-IR analysis. Based on the results, the capability of montmorillonite (Mt, familiar swelling day) to plug the pores was lost upon getting exposed to ZSCLE aqueous solution, a finding which is promising for surfactant flooding in swelling porous media, especially in the cases where high brine salinity is limited. In contrast to water flooding, ZSCLE was able to do a uniform sweeping with an improvement of sweep efficiency at about 10.72%. It was concluded that in addition to interfacial tension reduction and lowering of the mobility ratio, the increasing of the pore connectivity is another key parameter which is strongly effective in oil recovery improvement using ZSCLE. The, adsorbed ZSCLE on Mt particles resulted in a significant decrease in the absolute magnitude of zeta potential and an increase in particle size. From FT-IR analysis, some new picks were detected in infrared spectra of ZSCLE-modified Mt These indications suggest the interaction between hydrophilic head of ZSCLE and oxygen atoms available on the surface of Mt. This study presents a new criterion for selecting appropriate surfactants so as to stimulate the reservoirs rich in active clays. (C) 2016 Elsevier B.V. All rights reserved.