1. Methane Hydrate Production Technology Research Group, Energy Process Research Institute, Department of Energy and Environment, National Institute of Advanced Industrial Science and Technology (AIST), Tsukisamu-Higashi, Toyohira-Ku, Sapporo 062-8517, Japan
2. School of Earth, Energy and Environmental Engineering, Faculty of Engineering Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507, Japan