Mitsui Engineering and Shipbuilding Co., Ltd. Ichihara, Chiba, JAPAN

iwasakir@mes.co.jp

　

The demand of natural gas has recently been increased in terms of environment and stable supply source of energy. It is particularly increasing in Asian and Oceanian areas. With the demand sharply rising, while the supply staying constant, there may be a state in the future where the procurement of the natural gas is endangered.

　

Meanwhile, there are many small gas fields in Asian and Oceanian areas, to which the transport and storage by LNG system cannot be applied for economic reason. The effective exploitation of such small gas fields could be one of the answers to such demand-supply problem in the future.

　

Since, LNG system is not applicable to the small gas fields, another system for natural gas transport as economical and effective, as the existing LNG system has to be developed.

　

Natural Gas hydrate can contain a lot of gas in it and its production, transport and storage can be made under milder thermal condition than that of LNG. Mitsui Engineering & Shipbuilding Co., Ltd., utilizing such characteristics of natural gas hydrate, is now developing a integrated system for its production, pelletizing, storing, oeean transporting, until gasification.

　

This report describes the results of our experiments using methane hydrate to verify each component technology such as production, pelletizing, storing and gasification technologies. Through various experiments on such component technologies, the feasibility of the transport system of natural gas hydrate has been confirmed.

　

　

¹National Maritime Research Institute Tokyo, JAPAN

　

²Mitsui Engineering and Shipbuilding Co., Ltd. Tokyo, JAPAN

　

³Mitsui Engineering and Shipbuilding Co., Ltd. Chiba. JAPAN

　

⁴Osaka University Osaka, JAPAN

shirota@nmri.go.jp

　

Almost all natural gas consumed in Japan is liquefied at a low temperature below (120K), and is transported by LNG (Liquefied Natural Gas) carriers. In such way of transportation, large energy is consumed for producing LNG. If we can utilize ' self-preservation' property of gas hydrate economically in addition to its high-density gas containing property, it is possible to store and transport stranded natural gas at higher temperature and lower pressure compared to the conventional LNG method.

　

The authors had a hopeful prospect that natural gas hydrate (NGH) could be a medium for natural gas transportation, examining the properties of hydrate, handling and quality control for some NGH cargo forms. The authors also found that marine transport of natural gas in the form of natural gas hydrate pellets (NGHPS) would be available, and started the three-year research project last year under the financial support by the Corporation for Advanced Transport & Technology.

　

The project consists of (1) the investigation on microscopic properties of a single NGHP by using laser Raman spectroscopy and plasma replica method, (2) the evaluation of thermal and mechanical properties of NGHPs, and (3) the conceptual design of an NGHP carrier, i.e., specially constructed bulk carrier fitted with insulated cargo holds.

　

In addition to the whole plan of the research project, some results are introduced in the meeting, regarding preliminary NGHPs' self-preservation experiments, etc.

　

　

P. P. Shirshov Institute of Oceanology Russian Academy of Sciences Moscow, RUSSIA

pavlovskii@mtu-net.ru

　

Experimental researches ensure modeling of some natural phenomenons taking place at gas migration and oil gas formation processes in sedimentary stratum. Special method and installation have been developed and provide generation of helium-dispersed flux due to high pressure. Several experiments with different layers of artificial filters, sandy, upper marine sediment and water imitate filtration of helium stream through sedimentary stratum . Gas flux velocity has been measured during long investigation. Visual and instrumental observation has give an opportunity to find out unknown phenomenon of dispersed gas flux concentrating, transform into free gas state and gas piling up inside the layer of less penetration. Experiment brings to imitation of secondary gas deposit production.

　

The modeling data and conclusion conform to natural gas biogeochemical research results. Gas crater, seepage, plume corroborate the view of quick fluid flow exposure from sediment into water including free gas accumulations. Under high deep pressure dispersed fluxes of endogenous gases (helium, hydrogen, carbon dioxide) move upstairs and penetrating into sediments provoke such processes as: gases transition alternately from dispersed from into free state, making first and secondary gas deposits, stimulation activity of microbial community with hemolitoauthotrophic type of metabolism and methane generation, formation active biological state of sediments and near bottom water.

　

　

P. P. Shirshov Institute of Oceanology Russian Academy of Sciences Moscow, RUSSIA

balanyuk@sio.rssi.ru

　

One among the most perspective direction in studying the ocean floor is the research of hydrothermal fields within the most active zones ― rift valleys, where the processes of spreading of the .ocean floor, uplifi of the deep matter to the surface of the ocean floor, and creation of the new oceanic crust occur. Volcanic activity in these zones is accompanied with the formation of the hydrothermal system executing separation, transfer, and precipitation of a series of chemical elements. It is known that ore deposits with high concentration of iron, manganese, copper, nickel, cobalt are formed as a result of hydrothermal activity. It is much less known that hydrothermal activity in these zones has important but not so evident result ― the formation of hydrocarbons in the form of methane hydrates.

　

We propose the hypothesis of formation of methane hydrate deposits over the shallow slopes of the mid-oceanic ridges as an outcome of the action of two factors: the thermal convection of water in fractured-porous rocks of the crust and the reaction of serpentinization of the crust. The intensive exhalation of hydrocarbons takes place in the process of serpentinization. The conditions of water convection in the porous media are favorable for the formation and accumulation of methane hydrates in the near-surface layers of the oceanic crust. The carbonic-acid gas dissolved in the seawater is involved into the process of methane hydrate fomration. It was established that the most favorable conditions for this mechanism are over the slopes ofthe Mid-Arctic Ridge.