Recently, methane hydrate is being considered as a possible next generation energy resource replacing oil and natural gas. The amount of methane hydrate is estimated to be about 6 trillion m3 in the deep seabed around Japan which is equivalent to 100 years' supply, based on the present level of natural gas consumption in Japan. In order to progress exploitation methods, in 2001, the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) was established. In the present review, the basic properties of methane hydrate and potential areas where it exists are considered and the activities of the MH21 Research Consortium are described. Methane hydrate in the Nankai trough area, which is considered to be a potential reservoir, exists in the pore spaces among sand particles cementing them and is stable under given pressure and temperature condition. Several production methods have been proposed to extract the gas from hydrates, namely, heating, depressurization and inhibitor injection methods. There are many uncertainties in the production process, especially related to changes in the physical properties of hydrate bearing sediments caused by the dissociation of hydrate. To solve such uncertainties, experimental and analytical geotechnical studies have been carried out at Yamaguchi University in particular. The mechanical properties of methane hydrate-bearing sand are explained based on the experimental findings using the low temperature and high pressure triaxial testing equipments developed by the authors. Additionally, constitutive and numerical models for methane hydrate bearing sand to simulate the behavior of sediment during methane hydrate production are presented.
