The stability of a natural gas hydrate during storage at atmospheric pressure and below-freezing temperatures was studied in the laboratory. The gas hydrate was produced in a stirred vessel at 2-to 6-MPa pressure and temperatures from 0 to 20°C. The hydrate was refrigerated and stored in deep freezers at -5, -10, and -18°C for up to 10 days. The natural gas hydrate remained stable when kept frozen at atmospheric pressure.

Natural gas hydrates from different types and concentrations of surfactant solutions were produced in a high-pressure cell. An anionic, a cationic, and a nonionic surfactant were used to prepare different concentration of surfactant solutions from deionized water. Although the thermodynamics of hydrate formation from a gas mixture is not affected with the existence of surfactants in the environment, there is an appreciable effect of type and concentration of surfactant on hydrate formation rate. The hydrate formation rate is increased with the use of anionic surfactant for all concentrations tested. Hydrate formation rate is also increased at low concentrations of cationic surfactant. The effect of nonionic surfactant is less pronounced compared to anionic and cationic ones.

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Natural gas hydrate (NGH) technology is an attractive alternative to capture associated gas on FPSO's to solve the stranded and marginal gas problem in the oil industry. Based on estimates for land-based plants, the capital cost of hydrate technology is considerably lower than LNG, methanol and syncrude technologies. Offshore-based hydrate plants are also expected to be lower in costs. Crude/hydrate slurry processes are being developed for use on FPSO's. NGH technology is safe, environmentally friendly and easily scaleable. P. 247

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