Effect of mixed compounds on methane hydrate formation and dissociation rates and storage capacity

To use gas hydrates for storage and transport of gas, the hydrate should be reasonably stable. Surfactants were found to increase the hydrate formation rate and storage capacity. On the other hand, they accelerate its decomposition rate. This study is concerned with methods of decreasing the dissociation rate of methane hydrate formed in the presence of sodium dodecyl sulfate (SDS). Using SDS solution with concentration of 500 ppm, the hydrate formation rate increased by the factor grater than 35 and the storage capacity was doubled. Below the ice point however, the stability of hydrate decreased effectively. While after 10 h 2.3 mol% of methane hydrate in pure water was dissociated at 268.2 K, the dissociation percentage was 9.7 wt.% for the hydrate formed in the SDS solution. By addition of a minor amount of xanthan or starch (so as to reach a concentration of 100–300 ppm in the solution) the dissociation rate of the methane hydrate was decreased effectively.