Methane hydrate (MH) is expected as a new energy source. To predict gas productvity from a MH sediment, it is necessary to make numerical model for various phenomena in order to develop a numerical simulator and carry out some parametric study for various reservor conditons and production methods. In this study, we have carried out measurements of permeability by using artificial MH sediments. To reproduce the flow condition of gas and water in a real MH field, we attempted to measure the permeability of artificial MH sediment under the horizontal radial flow condition by using disc shape samples. From experimental results, the relationship between MH saturation and permeability was clarified, and we discussed permeability change in the process of MH dissociation by depressurization.


Methane hydrate is ice-like solid substance in which water molecule structure contains embedded methane molecules under low-temperature and high-pressure conditions (Sloan, 1998). When 1 m3 of MH is decomposed, about 150m3 of methane gas is produced. MH is one of the potential resources of natural gas in the near future, because the large amount of reservoir exists in marine sediments or in permafrost regions worldwide (Okuda, 1993; Sato et. al, 2001a, 2001b). Some extraction methods of MH from the reservoir in marine sediments has been proposed, such as depressurization, thermal stimulation and inhibitor injection. These are all based on the in-situ dissociation process of MH that is transformed into methane gas and water. Only methane gas can be produced from the reservoirs in marine sediments. To evaluate the productivity of methane gas from the reservoirs, it is necessary to develop the production simulator and carry out parameter study by using the simulator. Especially, it is very important to estimate the properties and the permeability of MH reservoir in such situations as dissociation and consolidation.

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