Vol.5 No.2 2012

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シンセシオロジー 研究論文−89−Synthesiology Vol.5 No.2 pp.89-97(May 2012)1 IntroductionIn Japan, most of the fossil fuels used as primary energy sources are imported from overseas. As natural gas is a relatively environmentally clean energy resource compared with crude oil or coal, its demand is increasing worldwide. Methane hydrate is a crystalline material comprised of methane and water molecules under high-pressure and/or low-temperature conditions. The crystalline structure of methane hydrate is shown in Figure 1. Methane hydrate is naturally distributed in permafrost and subsea environments, which are believed to contain huge amounts of potentially extractable natural gas, of which methane is the main component (thus comes the term ‘methane hydrate’). The existence of methane hydrate has been confirmed in offshore areas of Japan (Figure 2), particularly in the Nankai Trough, by means of observations made by bottom simulating reflectors (BSR)[1]-[3]. Therefore, it is believed that methane hydrate will become a valuable domestic energy resource of Japan once its production technique is established. To this end, the Ministry of Economy, Trade and Industry (METI) launched the Methane Hydrate Research and Development Program, and the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) was established. In the eastern Nankai Trough area, sedimentary core samples were obtained by the MH21 Research Consortium aboard the research vessel JOIDES Resolution. Laboratory analysis of sedimentary core samples taken from the eastern Nankai Trough area revealed that the concentration of methane hydrates is very small and methane hydrates exist within the pore spaces of sandy sediments. Kida et al. summarized the chemical characteristics of these sediment samples[4].Several methods have been proposed for recovering natural gas from methane hydrate reservoirs, including Jiro NagaoDevelopment of methane hydrate production method- A large-scale laboratory reactor for methane hydrate production tests -Natural gas hydrates off the shores of Japan are valuable resources for the country. To utilize these resources, it is necessary to establish a gas production technology and investigate suitable conditions for extraction of methane from methane hydrate reservoirs. While core-scale dissociation experiments yield reproducible results on how methane hydrate dissociates under various conditions, a production test at a real gas field would provide information about the type of dissociation phenomena occurring in a geological reservoir field. The performance of natural gas production from methane hydrate reservoirs is dependent upon the size and characteristics of reservoirs, such as temperature and permeability. In other words, while a core-scale dissociation test in a laboratory can demonstrate the heat transport process, dissociation in an actual reservoir is dominated by the material flow process. Thus, I believe that it is important to couple data obtained from core-scale tests with the results of field-scale tests by using a large-scale laboratory reactor in which dissociation experiments can be conducted under similar conditions to the actual reservoir. In this paper, I report the goals of the Methane Hydrate Research and Development Program being conducted by the Ministry of Economy, Trade and Industry, Japan, and describe the research objective of a large-scale laboratory reactor for methane hydrate production tests at MHRC (Methane Hydrate Research Center) of AIST (National Institute of Advanced Industrial Science and Technology).Keywords:Methane hydrate, the Methane Hydrate Research and Development Program, MH21 Research Consortium, gas production method and modeling, large-scale laboratory reactorMethane Hydrate Research Center, AIST 2-17-2-1 Tsukisamu-Higashi, Toyohira, Sapporo 062-8517, Japan E-mail: Original manuscript received September 29, 2011, Revisions received November 16, 2011, Accepted November 16, 2011Fig. 1 Crystalline structure of methane hydrate Water molecules form “cage” structures, and methane gas molecules are captured in the water cages.

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