Stability of carbon dioxide foam and effect of polymer on its foam properties

Considering the special nature of CO₂ and the behavior of CO₂ foam in the porous medium different from foams of other gases, CO₂ foam stability, decay property of CO₂ foam and effect of partially hydrolyzed polyacrylamide (HPAM) on CO₂ foam properties were studied. The gas-flow method was used for foaming and sodium dodecyl benzene sulfonate (SDBS) was used as the foaming agent. The stability of CO₂ foam was worse than that of N₂ foam under the same conditions and was nearly not influenced by surfactant concentration. Besides, the decay curve of CO₂ foam was approximately a straight line and the volume of CO₂ foam decreased rapidly after foaming. An important factor leading to the poor stability of CO₂ foam lay on the large film permeability coefficient because of higher solubility of CO₂ in water, which further led to the different propagation behavior of CO₂ foam from N₂ foam in the core. The adding of polymer HPAM enhanced the stability of CO₂ foam to a certain extent, but reduced the foaming property of surfactant solution. Therefore, both foam stability and foaming property of surfactant solution should be considered to determine the optimal concentration of polymer in the actual application.