Static Adsorption of Novel Synthesized Zwitterionic Surfactants on Carbonates

Surfactants are injected as additives into oil reservoirs to improve the efficiency of pore-scale displacement. Lately, zwitterionic surfactants have received enormous attention due to their unique properties. Nonetheless, the adsorption behavior of this class of surfactants onto the reservoir rocks was not properly elucidated. In this study, the static adsorption mechanism of betaine-type zwitterionic surfactants was explored on nonclay minerals (calcite, dolomite, and quartz), clay minerals (montmorillonite), and a carbonate outcrop. The adsorbents were well characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to understand their mineralogy and morphology, respectively. The surfactant was mixed with crushed reservoir rocks in a homogenizer for 24 h and then centrifuged. The supernatant solution of the effluent was studied using an high-performance liquid chromatography (HPLC) equipment to evaluate the adsorption of the surfactant onto the rock surface. Laboratory experiments indicate that the adsorption of surfactant was the lowest using calcite (1.068 mg/g of rock) and the highest on montmorillonite clay (22.091 mg/g-rock). Based on the surfactant headgroup, the magnitude of surfactant adsorption was in the order of sulfobetaine > hydroxysulfobetaine > carboxybetaine zwitterionic surfactant, respectively. The Redlich-Peterson model performed the best in modeling the surfactant adsorption behavior. Overall, the outcome of this study aids a better understanding of zwitterionic surfactant behavior and serves as an intuitive guide for the field application of this material for the enhanced oil recovery (EOR) process.