Enhanced Oil Recovery Performance Of Nanoparticle – Surfactant Stabilized CO2 Foams In Carbonate Reservoirs

Abstract

CO 2 flooding is one of the promising techniques for enhancing oil recovery. However, CO 2 flooding faces challenges due to gas channeling and viscous fingering, which are caused by reservoir heterogeneity and the mobility contrast between CO 2 and reservoir oil. The synergistic blend of interfacial tension reduction by surfactant and the strong adsorption of nanoparticles at the foam lamellae can produce foams that are significantly more stable and stronger in oil reservoirs than those stabilized by surfactant alone. However, the impact of nanoparticles on both the static and dynamic stability of traditional foams is not fully understood due to limited research. Therefore, this study aims to investigate the effect of silicon dioxide (SiO 2 ) nanoparticles on the bulk and dynamic stability of CO 2 foams stabilized by alpha-olefin sulfonate (AOS) surfactant. Bulk static stability tests were conducted to examine the effects of surfactant concentration, temperature, salinity, and nanoparticles on CO 2 foam stability. Additionally, the study compared the performance of surfactants, either alone or synergistically with nanoparticles, as CO 2 foaming agents for enhanced oil recovery at low and high temperatures. Core flooding experiments were performed on parallel core systems to assess the flow diversion capacity of CO 2 foam stabilized by surfactants or surfactants and nanoparticles. Dynamic core flooding experiments were conducted using Indiana cores, including CO 2 foam flooding in the absence and presence of oil. Bulk static tests demonstrated that above the critical micelle concentration (CMC), CO 2 foam stability remained unchanged as surfactant concentration increased. The addition of nanoparticles improved the stability of surfactant-stabilized CO 2 foam by preventing bubble coalescence and reducing liquid drainage. In the presence of oil, CO 2 foam rapidly loses stability upon contact, decaying quickly. Like the bulk static tests, foam generated in porous media demonstrated low stability at high temperatures. Dual-core studies showed that CO 2 foam was effective in diverting flow at various levels of heterogeneity, thereby improving sweep efficiency. The synergistic effect of surfactant and nanoparticles resulted in higher apparent viscosity than using surfactant alone. Furthermore, CO 2 foam stabilized by the combination of nanoparticles and surfactant recovered more oil than surfactant-stabilized foam under both low and high-temperature conditions. It is hoped that the outcomes of the laboratory work and numerical simulations in this research will contribute to the advancement of nanoparticle-surfactant foam applications for controlling CO 2 mobility.