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.

Dynamic adsorption of a zwitterionic-type surfactant cocamidopropyl hydroxysultaine on limestone cores at oil reservoir conditions, i.e., under 2000 psi pressure, 130 °C temperature, and in the presence of seawater with 30 800 ppm NaCl, has been studied through core-flood displacement tests and in the absence of oil, at an injection rate of 120 cm3·h–1 up to 60 pore volumes (PV). The amount of adsorbed surfactant has been determined from mass balance by calculating its concentration through high performance liquid chromatography (HPLC). The normalized surfactant concentrations (NSC) have been used in terms of the PV, and then they are obtained the corresponding dynamic adsorption curves. Dynamic adsorption isotherm curves of the zwitterionic surfactant diluted in seawater showed a steep rise between 1 and 3 pore volumes (PV), and the saturation conditions were kept up to 60 PV. An average surfactant adsorption of 0.1138 ± 0.0126 mg·g–1 was determined. Quantum theoretical studies show that the electronic energy gap of (104) the limestone is electrically neutral, preferably acquiring a negative charge tendency, these results imply that the calcite surface will preferentially interact with positive ions, so that the cations present in the solution interacting in the limestone, resulting in a positive charge in the rock that implies that the surfactant cocamidopropyl hydroxysultaine interacts in the rock by the anionic group.

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The adsorption of a supramolecular surfactant formed by the non‐covalent interactions among sodium (E)‐dodec‐2‐ene‐1‐sulfonate, sodium 3‐hydroxydodecane‐1‐sulfonate and 3‐[(3‐dodecanoylamidopropyl)dimethylazaniumyl]‐2‐hydroxypropane‐1‐sulfonate onto limestone under static and dynamic conditions in the presence of seawater and connate water is presented. In the static test at 70°C and atmospheric pressure, the adsorption capacity of the saturated monolayer was 8.65 mg/g for seawater and 4.05 mg/g for connate water. This behavior was associated with the increase of the critical micellar concentration from 217 ppm in seawater to 672 ppm in connate water, which is related to the capacity of the supramolecular surfactant to form complexes at high salinity and hardness. The dynamic experiment was carried out at 130°C with a pressure of 16,500 kPa, a flow rate of 90 mL/h and a dose of 2000 ppm of the surfactant. An adsorption of 0.230 mg/g was found in seawater, while a value of 0.109 mg/g was obtained in connate water, consistent with the static experiment. In addition, spontaneous imbibition experiments for connate and connate water with 2000 ppm of surfactant showed an increase in the oil recovery factor from 3% to 17% in the presence of surfactant at 100°C. It was observed that the rock changed from oil‐wettable to water‐wettable, indicating that the supramolecular complex retains its capability to form the monolayer on the rock surface. In contrast to the ionic and cationic conventional surfactants, the experimental evidence indicates that the surfactant preserves its properties under the extreme conditions found in mature Mexican carbonate reservoirs.