Evaluation of Temperature on the Methane Hydrates Formation Process Using Sodium Surfactin and Rhamnolipids

The performance of chemical and biological additives in the methane hydrates formation and dissociation processes is of relevance for the development of gas-transport and gas-storage systems. The effect of sodium surfactin, rhamnolipids, and sodium dodecyl sulfate (SDS) on the methane hydrate formation process was assessed in this work at different temperatures and a fixed pressure of 50 bar. The studied parameters were induction time, methane uptake, period to reach 90 percent of the consumed gas, water-to-hydrate conversion, and formation rate. Concentrations for sodium surfactin were 3, 150, 750, 1500, 2000, and 2500 ppm, while rhamnolipids and SDS solutions were analyzed at 1500, 2000, and 2500 ppm. Performance testing of these additives was carried out by means of the isochoric-isothermal method. The experimental setup consisted of an isochoric three-cell array with 300 mL of capacity and magnetic stirring. According to the results, the sodium surfactin promoted the methane hydrate formation since the kinetics were higher and the water-to-hydrate conversion averaged 24.3%; meanwhile, the gas uptake increased as concentration was rising, and the induction time was reduced even at a temperature of 276.15 K.