Experimental and numerical studies of natural gas hydrate dissociation by depressurization in different scale hydrate reservoirs
Gas production from hydrate reservoir by depressurization is considered the most feasible approach up to date.However, the study on the theory and law of production is fairly scarce.In this paper, experimental work of the decomposition of methane gas hydrate by depressurization in porous media was carried out with the 1D experimental apparatus.A one-dimensional mathematic model was built, which considered natural gas hydrate dissociation kinetics and flow inporous media.This model was used to fit the experimental data, and the derived intrinsic dissociation kinetics constant was in the order of 102 mol·m-2·Pa-1·s-1, which was three orders of magnitude lower than that derived from bulk hydrate dissociation.The model also suggested that the hydrate dissociation kinetics had a great effect on the gas production behavior for the laboratory scale hydrate reservoir.However for a field scale reservoir, the hydrate dissociation kinetics had little effect while the flowability dominated the gas production behavior.