Production, Transportation and Storage of Natural Methane Hydrate

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A large amount of Methane Hydrate has been discovered below the seafloor of deepsea of Exclusive Economical Zone of Japan. Transportation technology of Natural Gas in terms of Natural Gas Hydrate (NGH) pellet is under development for economical production of Natural Gas from small scale Gas fields. This research investigated feasibility of Production-Transportation-Storage system of deepsea Methane Hydrate by making the system more efficient introducing the NGH pellet transportation. The feasibility of stockpile of Natural Gas in terms of NGH pellet was also investigated from energy security point of view.Firstly, development system was grouped into processes, 1)Drilling and production, 2)Floating production system, 3)Production of NGH, 4)Loading-Transportation-Unloading, 5)Storage and 6)Regasification. Cost estimation formulas were formulated for elements of each process and the composition of cost of total system was clarified. Secondly elementary technologies necessary to realize the system were investigated.It was clarified that cost of NGH production process occupies a large potion in the total cost. It was also clarified that economical feasibility of floating production system itself is not so high under the cost of Natural Gas price before the recent steep rise of price. New type of NGH which shows very low rate of decomposition was discovered. Packing fraction characteristics of non-sphere pellet and two-sphere-size pellets system were clarified and effect of vibration on filling ratio was clarified. It was also clarified that NGH pellet is not dissolved in methane gas atmosphere at temperature of -85℃. For stockpile, heat transfer in the stockpile tank was investigated and the tank was planned. It was shown that the stock pile is feasible from view point of heat balance.