1. The Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, P. R. China
2. Laboratory for Marine Mineral Resources, Pilot National Laboratory for Marine Science and Technology, Qingdao 266071, P. R. China
3. Institute of Unconventional Oil and Gas Science and Technology Research, China University of Petroleum, Beijing 100249, P. R. China
4. Faculty of Engineering, China University of Geosciences, Wuhan 430074, P. R. China