Abstract
Nucleation, growth, and ageing of methane hydrate crystals were visually observed in a porous medium filled with liquid water presaturated with methane. The pressure-temperature conditions, at which hydrate formation was initiated, correspond to the following system subcoolings ; 3.4K and 14.1K. Faceted hydrate crystals grew and bridged the pore spaces without intervention of a liquid water layer when the subcooling was equal 3.4K. At the subcooling of 14.1K, the dispersive formation of dendritic crystals and subsequent morphological change into particulate crystals were observed. Dissociation behaviors due to heat input or depressurization were observed in the porous medium. Formation and permeation of methane gas bubbles or slugs observed during dissociation varied depending on the dissociation method.
