Effects of Mixed Surfactants on Methane Hydrate Formation and Dissociation

Abstract

Natural gas hydrates are ice-like crystalline and non-stoichiometric compounds formed by hydrogen bonds from water molecules when methane is trapped inside. Gas hydrates have received much attention not only as a new natural energy resource but also as a new means of natural gas storage and transportation. However, slow formation rate and stability of natural gas hydrates have been considered problems hindering the industrial applications. In this work, hydrate promoters, mixed MES and SDS, were investigated for hydrate formation and dissociation kinetic. The concentration of mixed surfactants were prepared at 0.5 mM MES/2 mMSDS, 1 mM MES/2mM SDS and 2mM MES/2mM SDS. The formation experiments were conducted in a batch reactor at 4 °C and 8 MPa. The results showed that all concentrations of mixed surfactant enhanced methane formation rate and methane consumption compared to pure water. The mixture of 0.5 mM MES and 2 mM SDS showed the highest methane consumption, while all concentrations of mixture showed the same rate of formation. The dissociation experiment was conducted after the formation with the driving force of 25 °C. The results showed that all promoters did not significantly affect the rate and methane recovery.