Fundamental Study on the Development of Gas Hydrate
Geo-Engineering System Division
Geotechnology Department |
- Objectives
- An enormous amount of natural gas hydrate is estimated to exist in ocean sediment deeper than 300 m below sea level, and it is expected to produce natural gas from the methane hydrate in the early stage of coming century. The objective of this study is to find future research theme to realize gas extraction from gas hydrates in the ocean sediments.
- Results
- To achieve this object, we think it is fundamental that to promote understanding on gas hydrate itself and to elucidate the dynamic process of gas hydrate formation and dissociation to a molecular size revel. Then a research group was organized by members who belong to different research fields in NIRE such as mining, drilling, fluid mechanics, safety, crystal science and computer science.
- Firstly, Dr. G. Holder, Dr. J. Ripmeester and Dr. P. Crancy, famous scientists in the field of gas hydrate, were invited to NIRE and a workshop on gas hydrate was held to exchange R/D activities on gas hydrates with helps of other organizations in Japan.
- In 1995-1996, "A study on molecular controlled mining system of methane hydrate" was carried out. In 1997, "Preliminary study on the development of on-shore methane hydrate around Japan" commenced with financial support of the New Sunshine Program", MITI, as the three years joint research between three national research institutes including NIRE and private sectors.
- Our research group focused efforts on several subjects as follows:
- a) Characteristic of gas hydrate: In the process of gas production from gas hydrate, phase changes of gas hydrate cannot be avoided, therefore understanding of dynamic phase change should be made clear with various techniques such as a molecular dynamic analysis, investigation on water cluster characteristics, experimental investigations on the dynamic process of gas hydrate dissociation at interface between solid hydrates and fluid. To realize an actual phase control of natural gas hydrate, it is necessary to make clear the heat and mass transfer at different scale fields from 10-10m (molecular scale) to 103m (reservoir scale).
- b) Proposal of gas production concept from gas hydrate in ocean sediment: For the gas production from hydrates and the seabed stability after the production, we proposed a new concept. The figure illustrates the molecular mining method by means of CO2 injection in order to extract CH4 from gas hydrate reservoirs. The concept is composed of three steps as follows; 1) injection of hot sea water into the hydrate layer to dissociate the hydrates, 2) produce gas from the hydrate, 3) inject CO2 to form carbon dioxide hydrate with residual water to hold the sea bed stable.
| National Institute for Resources and Environment |
