A great challenge for the foam application for enhanced oil recovery (EOR) is maintaining its long-term stability in the reservoir, especially for the high-salinity and/or high-temperature reservoirs where the commonly used surfactants tend to either degrade or precipitate. CO2 flooding is sometimes implemented for EOR in reservoirs which contain natural fractures. Extensive literature on CO2 EOR processes is available and excellent monographs on CO2 EOR processes are available. One critical weakness of the CO2 EOR process is the low viscosity and low density of CO2. The chapter discusses the generation and characterization of CO2 foams both in bulk state and in porous media, and their rheological and transport behaviors in reservoir rocks. It explores the use of nanoparticle-stabilized emulsions for EOR and conformance control. As with the CO2 EOR case, where the use of surfactant as a stabilizer is difficult due to its degradation at high-temperature condition, use of nanoparticle is a good alternative.