Adsorption of Zwitterionic Surfactant on Limestone Measured with High-Performance Liquid Chromatography: Micelle−Vesicle Influence David Aaron Nieto-Alvarez,* ,†,‡ Luis S. Zamudio-Rivera,* ,†,§ Erick E. Luna-Rojero, ∥ Dinora I. Rodríguez-Otamendi, ‡ Adlaí Marín-Leó n, ‡ Raú l Herna ́ ndez-Altamirano, ⊥ Violeta Y. Mena-Cervantes, ⊥ and Toma ́ s Eduardo Cha ́ vez-Miyauchi # † Grupo de Química Aplicada a la Industria Petrolera, ‡ Direcció n Regional Marina, § Programa de Ingeniería Molecular, and ∥ Programa de Recuperació n de Hidrocarburos, Instituto Mexicano del Petró leo, Eje Central La ́ zaro Ca ́ rdenas 152, Colonia San Bartolo Atepehuacan, Mexico City 07730, Mexico ⊥ Centro Mexicano para la Producció n ma ́ s Limpia, Instituto Polite ́ cnico Nacional, Avenida Acueducto s/n, Colonia La Laguna Ticoma ́ n, Mexico City 07340, Mexico # Facultad de Ciencias Químicas, Universidad La Salle Me ́ xico, Benjamin Franklin 47, Colonia Hipó dromo Condesa, Mexico City 06140, Mexico * S Supporting Information ABSTRACT: Herein is presented a new methodology to determine the static adsorption of a zwitterionic surfactant on limestone in three different aqueous media [high-performance liquid chromatography (HPLC) water, seawater, and connate water] with the use of HPLC at room temperature and 70 °C. The results showed that, in both HPLC water and seawater, the surfactant adsorption followed a monolayer Langmuir tendency. In contrast, for connate water, the surfactant presented a new adsorption profile, characterized by two regions: (i) At surfactant concentrations below 1500 mg L −1 , an increase of adsorption is observed as the amount of divalent cations increases in the aqueous media. (ii) At surfactant concentrations above 1500 mg L −1 , the adsorption decreases because the equilibrium, monomer ⇆ micelle ⇆ vesicle, is shifted to the formation of vesicles, giving as a result a decrease in the concentration of monomers, thus reducing the interaction between the surfactant and the rock, and therefore, lower adsorption values were obtained. The behavior of the surfactant adsorption under different concentrations of divalent cations was well-described by the use of a new modified Langmuir model: (dΓ/dt) ads = k ads c(Γ ∞ − Γ) − k cmc (c − c cmc ) n ΓH(c − c cmc ). It was also observed that, as the temperature increases, the adsorption is reduced because of the exothermic nature of the adsorption processes. 1. INTRODUCTION Oil recovery is carried out in three phases. Primary recovery: Oil is pushed out to the surface because of the pressure gradient between the reservoir and the wellhead. Secondary recovery: When the wellbore pressure decreases, pressurized gas or water is injected into the reservoir to maintain the pressure gradient and drive the residual oil. After primary and secondary phases, the reservoir still contains 60−80% of the oil. When the reservoir pressure decreases during the secondary phase, it is necessary for the implementation of the tertiary extraction, also known as enhanced oil recovery (EOR), which is the generic name for processes and techniques applied to increase the hydrocarbon recovery factor by modifying the original physicochemical properties of the reservoir. EOR 1−3 has received particular attention in recent years because of its potential application in carbonate reservoirs, because global hydrocarbon recovery has been estimated much less than 30% and 50% of the known reservoirs are carbonate- type. Carbonate reservoirs are often characterized as highly fractured and with very low relative permeability, and it is also known that 90% of these reservoirs are considered neutral to preferably wet to oil. As mentioned, the EOR purpose is to modify the physicochemical properties of the reservoir to increase the oil recovery factor, specifically the interaction between the rock and the reservoir fluids. 4−6 In this sense, one of the most promising processes for achieving this purpose is the injection of chemical compounds that modify the wettability of the rock, promoting the spontaneous imbibition of the oil from the matrix. It is important to notice that, for the application of these Received: May 22, 2014 Revised: September 24, 2014 Published: September 25, 2014 Article pubs.acs.org/Langmuir © 2014 American Chemical Society 12243 dx.doi.org/10.1021/la501945t | Langmuir 2014, 30, 12243−12249