Improvement of Hydrate Production and Storage Condition to be Used for Natural Gas Storage and Transportation

To use gas hydrates for storage and transportation of natural gas, three factors of hydrate formation rate, stability and storage capacity should be considered. In recent years, some additives mainly surfactants have been used to increase hydrate formation rate and storage capacity but they usually increase hydrate dissociation rate too. The major objective of this study is to investigate the effect of water-soluble biological potato starch as a suitable promoter on the formation rate, storage capacity and stability of methane hydrate for production in optimum condition to be used for natural gas storage and transportation. Potato starch was tested with concentration of 200 ppm and compared with the hydrate formed in pure water and aqueous sodium dodecyl sulfate (SDS) solution. Hydrate stability tests were performed at two temperatures of 263.2 and 268.2 K with and without additives at two pressures of 1 and 10 bar. It has been found that potatoe starch effectively increases the hydrate formation rate and storage capacity. Also results revealed that the stability of hydrate formed in starch solution is similar to that of pure water at different conditions. The best operating condition for storage was the pressure of 10 bars and temperature of 268.2 K. Eventually, an economic study revealed that for transportation of 3.5 billion SCM/year of methane gas in hydrate form for a distance of 5500 km, the capital cost could be decreased by 14% using starch with concentration of 200 ppm.