Effect of Surfactant on Stability and Size Distribution of Gas Condensate Droplets in Water

Emulsions are mixtures of two immiscible liquids in which one liquid is dispersed in the other as fine droplets. In this work, different surfactants, including nonionic, anionic, and cationic surfactants, are used to form gas condensates in a water emulsion along with four kinds of surfactant: Span 80, Tween 80, CTAB, SDS, and the mixture of Span 80 and Tween 80. In order to evaluate the stability of these emulsions, the droplet size distribution is measured by an optical microscope. Having the lowest Sauter mean diameter of droplets, emulsions with Tween 80 and the combined Tween 80 and Span 80 surfactants had the most stability. The effect of gas condensate concentration in water was assessed, and the results revealed that solutions containing 0.022 mass fraction of gas condensate are more stable than those containing 0.044. The addition of nonionic surfactants had a better potential to improve emulsion stability, in comparison with cationic and anionic surfactants. Moreover, to investigate the stability of the emulsion, some stable emulsions were then demulsified with an EO/PO block copolymer of dodecan-1-ol. Results signified adding demulsifier caused gas condensate droplets to grow (about 200% growths), which resulted in a good coalescence.