Experimental investigation of CO2-foam stability improvement by alkaline in the presence of crude oil

The results show that while addition of NaOH drastically decreases the stability of CO2-foam, Na2CO3 and, in particular, Borate can significantly increase the stability of CO2-foam. For these alkalis, there is an optimum concentration which corresponds to maximum foam stability. The results also reveal that higher oil viscosity increases the stability of CO2-foam. Anionic surfactants with smaller carbon number produce better foam stability compared to non-anionic surfactants. As expected, foam stability increased with increasing surfactant concentration but there was an optimum surfactant concentration corresponding to maximum foam stability beyond which foam stability decreased. The results also revealed that N2-foam was more stable compared to CO2-foam.