A contrasting analysis of CO2 and N2 foam flood for enhanced oil recovery and geological storage of CO2

Foam flooding using CO₂ has emerged as a promising method for both enhanced oil recovery (EOR) and the storage of CO₂ in geological reservoirs. This study conducts a thorough analysis of the behavior of CO₂ and N₂ foams in bulk and porous media, utilizing bubble-scale analyses and foam flooding experiments. The study compares the foamability and longevity of CO₂ and N₂ foams, with findings indicating that N₂ foam bubbles tend to be smaller and less varied in size than CO₂ foam bubbles, leading to increased foam stability. Additionally, the study compares the half-lives of CO₂ and N₂ foams generated through sparging and winding methods, showing that N₂ foam has half-lives 22 and 10 times greater than CO₂ foam when produced using the sparging and winding methods, respectively. Furthermore, CO₂ foam generated through the sparging method had a lower foaming volume than N₂ foam due to CO₂'s solubility. In the foam flooding experiments, N₂ foam proved more effective in recovering oil from porous media than CO₂ foam, thus demonstrating the effectiveness of the foam injection procedure. These results offer valuable insights into the differing performance of N₂ and CO₂ foam floods for EOR and CO₂ geological storage.