Growth of Methane Clathrate Hydrates in Porous Media

The growth processes of methane hydrates in porous media were investigated using attenuated total reflection infrared (ATR-IR) spectroscopic and optical microscopic techniques. The ATR-IR spectra revealed that hydrates in porous media grew in two steps. Discrete hydrate growth in two steps was observed, despite several degrees of subcooling. In the first step, film-like hydrates were formed at the gas water interface. Visual observations showed that the hydrate films collapsed and then fresh liquid-phase H2O molecules, from the cracks in the film, entered the hydrate phase. In porous media, the cracks in the hydrate film were found to change the nature of the hydrate from a film to a cement-like hydrate. Two-step growth reflects the change in the nature of hydrates formed in porous media.