Development of a High Efficient Compound Surfactant for Foam Drainage in Gas Wells

Abstract

Abstract In this study, the foaming properties of a compound surfactant formula containing cetyltrimethylammonium chloride (CTAC), cocamidopropyl betaine (CDAB), fatty alcohol polyoxyethylene ether-7 (AEO7) and sodium alpha-olefin sulfonate (AOST) were evaluated to meet the application requirements for foam generation and foam drainage in gas wells. The results exhibited that the foaming volume and the half-life of the compound surfactant solution (0.05 wt % CTAC + 0.7 wt % CDAB + 0.6 wt % AEO7 + 0.05 wt % AOST) can reach the values of 550 mL and 23 min, respectively, which suggested that the foaming ability and stability were improved in comparison with each solution containing a single surfactant. It showed that the surface tension can be lowered to 22.4 mN/m with the presence of the compound surfactants. Simultaneously, the microstructure of the foam was observed using a polarizing microscope, and it was found that there were almost no polyhedron structures in the foam within a certain range of formula concentrations. The results of the experiments also clarify that the formula has well properties of temperature resistance and salt resistance (measured using a high-speed agitator).