Experimental simulation of hydrate accumulation and dispersion in pore fluids

Abstract

Dynamic accumulation and dispersion of gas hydrate in the stability zone are actually controlled by the transformations of methane between hydrate and pore fluid. In this study, hydrate formation and dissociation in sediment column was simulated, and the experiment shows that hydrate can nucleate either at the free gas-fluid interface or in the aqueous phase oversaturated with methane, in both fine and coarse sediments, but nucleates easier in the coarse sediments. The processes that methane dissolved from free gas and transported in aqueous solution to precipitate at the surface of hydrate crystal were monitored. Methane concentrations in saline water in equilibrium with hydrate in the absence of a vapor phase was studied by in situ Raman spectroscopy. Hydrate growth and dissolution induced by temperature changes was observed. The rate of growth and dissolution of methane hydrate is controlled by mass transportation in aqueous solution.