Using Gas Hydrates for Natural Gas Storage and Transportation

The methane hydrate formation and dissociation rates and storage capacity in pure water, an anionic surfactant (sodium dodecyl sulfate, SDS) and a cationic surfactant (cetyl trimethyl ammonium bromide, CTAB) aqueous solutions were investigated. In this work using pure water the hydrate formation rate and storage capacity was low though it had enough stability. Each surfactant with concentrations of 300, 500 and 1000 ppm was tested and it was found that SDS, prepared with these three concentrations speeds up the hydrate formation rate effectively. CTAB increased the formation rate at 1000 ppm but decreased at 300 and 500 ppm. Hydrate stability tests was performed at three temperatures 268.2, 270.2 and 272.2 K with and without surfactant promoters. The results showed that the tested surfactants increase the dissociation rate of methane hydrate below the ice point. SDS increased the dissociation rate more than CTAB and the results showed that the storage capacity of up to 165V/V was obtained with 1000 ppm of CTAB in water.

Keywords:

Gas hydrates , Formation rate , Dissociation rate , Storage capacity , Surfactants