Foam stability test for surfactants in enhanced oil recovery

Abstract

One challenge of foam application for enhanced oil recovery is the stability of foam when it is in contact with oil in the reservoir. This research studied the effect of surfactant structures, concentrations, brine, alkanes and the improvement on foam stability. Surfactants with different structure were evaluated using a shaking technique to firstly screen the appropriate structure that can create stable foam. Then, the rest of experiment was performed by purging a fixed gas flow gas through a certain amount of solution. Foam height was measured as a function of time. Six surfactants were used in this experiment. The results show that anionic surfactants gave better foam stability than nonionic surfactant. The anionic surfactant with shorter carbon chain length also generated better foam stability compared to anionic surfactants with longer carbon chain. Four surfactants that gave the best foam stability were chosen to study the effect of concentration. The higher concentration also increased foam stability but the foam tended to decrease when the concentration went beyond the optimum concentration. For the effect of different alkanes, the results showed that adding alkanes tended to destabilize the foam stability and alkanes with longer carbon chain gave foam more stable compared to shorter carbon chain. For the effect of brine, foam collapsed rapidly. To improve foam stability, adding co-surfactant also helped to improve foam stability in brine and co-solvent also enhanced the foam stability in the presence of alkane.