Stabilization of Carbon Dioxide Foam by Low Concentration of CTAB-grafted Nano-Faujasite Zeolite

Abstract

Nanoparticles received great attention as one of the most effective additives proposed to mitigate the destabilizing mechanisms of CO2 foams targeted for enhanced oil recovery (EOR) applications. The irreversible adsorption of nanoparticles at the gas/liquid interface assists the CO2 foam stability via three distinct but intimately connected mechanisms, namely: it enhances the foam liquid film dilatational viscoelasticity, which increases the ability of foam lamellas to withstand rupture against distortion; it retards film thinning and bubbles coalescence, and it minimizes the Ostwald ripening effect. While extensive studies investigated the synergistic effect between several types of surfactants and nanoparticles in enhancing CO2 foam stability, none of the previous studies proved to generate a stable CO2 foam at surfactant concentration below the critical micelle concentration (CMC). Furthermore, previous research relied on ultra-high nanoparticle concentrations which is non-economical. This thesis introduces an innovative technique of CO2 foam stabilization using environmentally friendly faujasite (FAU) zeolite nanoparticles grafted with effective cationic surfactant (CTAB) to enhance CO2 foam stability at surfactant concentrations below the CMC. The study involves arrays of characterization and stability evaluation techniques for the synthesized nanoparticles before and after surface grafting. Furthermore, the foamability and foam stabilization properties of the developed CTAB-FAU, both grafted and the physically mixed CTAB/FAU, dispersion in CO2 foam stabilization were assessed by studying the decay of foam volume, liquid holdup, and bubbles evolution in an in-house constructed foam evaluation setup developed using foam optical properties and machine learning. Moreover, the synergy between CTAB and FAU nanoparticles in enhancing the CO2 foam interfacial dilatational properties and surface shear viscosity was investigated under room conditions. The experimental findings were validated using the population balance model to evaluate the effectiveness of the nanoparticle dispersion in retarding foam bubbles' coalescence and liquid discharge destabilization mechanisms. The experimental and modeling results verified that CTAB-grafted nanoparticles were able to significantly optimize CO2 foam stability at a bulk concentration of ~150 ppm, whereas the physically mixed surfactant and nanoparticles dispersions require a bulk concentration of 1,000 ppm. Hence, the developed technique of surfactant grafted nanoparticles can provide an economical alternative to conventional gas EOR methods.