Foam Flooding for EOR: Viability in Modern Oil Reservoirs

As conventional oil reserves are declining at an alarming rate, a new approach to enhanced oil recovery (EOR) is the need of the era. As the gas injection is associated with the problem of viscous fingering as well as channeling of gas, there is need for such an agent that may be fruitful in reducing the mobility of gas and thereby enhances the volumetric sweep efficiency within porous media. As a result, the foam plays a vital role in EOR. Therefore, this chapter delves into the application of foams for EOR and elucidates the processes involved in their creation. The interfacial tension reduction and mobility control facilitated by foam lead to improved sweep efficiency and capillary desaturation. Stability of foams is highly influenced by lamellae, that is, the thin layer that separates the gas bubbles within foam system. Thinner lamellae are not recommended for EOR as bubble ruptures quickly, as a result, the role of surfactants was explored. Foams, formed by injecting gas into surfactant solutions, exhibit unique properties that enhance oil displacement in reservoirs. Surfactant based foam has the ability to migrate across porous and permeable rock surfaces, which in turns increases the surface tension between immiscible phases. The creation of stable foams involves optimizing surfactant concentration, gas injection rates, and reservoir conditions. This chapter also focuses on the composition of crude oil and its impact on foam stability as well as the stability of foam in depleted reservoir. The study emphasizes the mechanism by which foams generate a favorable mobility contrast, enabling efficient displacement of oil. This was followed by the use of viscoelastic surfactants and polymer in the foam system. Application of nanoparticles (NPs) and viscosifiers in making highly stable foam has also been discussed. NPs stabilizes the foam even at higher salinity and higher temperature by providing a strong barrier which prevents bubble coalescence. Use of viscosifiers enhances the life of foam by enhancing lamellae viscosity and thereby reduced lamellae drainage at elevated temperatures.