As for the development of methane hydrate that exists under bottom of the sea, the safety measures are most important. The methane hydrate development system using artificial block and prop system was proposed to prevent the landslide and the sudden fall. Artificial block system is a method of improving strength of the sediment by injecting carbon dioxide into the sediment.
It was assumed to form carbon dioxide hydrate in the bottom of the sea stratum to achieve this purpose, and so we examined the properties of formation / dissociation, and the influence of the particle. The results obtained are as follows;
(1) The formation condition approaches the estimated equilibrium value by mixing the particle, and the level of the shift depends on the correlation of the heat conductivity of the particle and water. It can be suggested that carbon dioxide hydrate be formed easily at the case without the stratum particle when the carbon dioxide bubble rises as a result within the space of the particle in the sediment. It is considered that the dissociation condition of carbon dioxide hydrate almost agrees to the estimated equilibrium value in any case, and is not influenced by the presence of the stratum particle.
(2) It has been understood that the supercooling phenomenon be comes smaller with increasing the particle diameter, and that the particle diameter has close relation to the formation condition of carbon dioxide hydrate. This shows that the formation condition changes according to the particle diameter of the sediment.
(3) The initial formation rate varies from the range of 0.2 to 0.6 ml / (min · g), and the dissociation rate varies from 1 to 1.5 ml / (min · g) in case of carbon dioxide hydrate. The rates increase with the presence of the particle, and also increase with the particle diameter.
We will continue to achieve the methane hydrate development system by the experiment that uses similar particles to the strata of the sea sediment in the future.
