HR: 1340h
AN: OS23A-1035    [Abstracts]
TI: Constitutive Equation of Variable Compliance Type for Artificial Sediment Containing Methane Hydrate
AU: * Miyazaki, K
EM: miyazaki-kuniyuki@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
AU: Masui, A
EM: akira.masui@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
AU: Haneda, H
EM: h.haneda@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
AU: Ogata, Y
EM: Yuji-ogata@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
AU: Temma, N
EM: tenma-n@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
AU: Aoki, K
EM: aoki-kazuo@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
AU: Yamaguchi, T
EM: t-yamaguchi@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, Ibaraki, 305-8569, Japan
AB: Methane hydrate (MH) is anticipated to be a promising energy resource of natural gas. In order to evaluate productivity of methane gas from MH reservoirs, it is necessary to develop a gas production numeric simulator. For precise assessment of long-term productivity, it is important to predict mechanical behaviors of MH reservoirs in consideration of their time-dependency. In this study, loading rate dependency, one of important time-dependent properties, of artificial sediment containing MH was experimentally examined. Results of triaxial compression tests of water-saturated sand (saturated-sand specimen) and sand containing synthetic MH (hydrate-sand specimen), at conditions of confining pressure 9 MPa, pore water pressure 8 MPa and temperature 278 K, were presented. Strain rate was changed alternately between two speeds at a constant strain interval. Experimental results indicate that saturated-sand specimen shows negligible small strain rate dependency. Strain rate dependency of hydrate-sand specimen was considerably stronger than that of saturated-sand specimen. Referring to earlier works, the time-dependency of hydrate-sand specimen seemed to be weaker than that of ice or MH and comparable with that of frozen sand. Based on the experimental results, constitutive equation of variable compliance type, which focuses on time- dependent behaviors, was applied to sand specimen containing MH as the first step towards formulation of mechanical properties of MH reservoirs. As a result, it was found that the previously reported results obtained in constant strain rate tests can be explained by the proposed equation. Moreover, by a numerical analysis using the equation, the prediction of long-term mechanical behavior can be made.
DE: 1822 Geomechanics
DE: 3004 Gas and hydrate systems
DE: 8020 Mechanics, theory, and modeling
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting