In order to confirm the hydrate characteristics the methane hydrate was formed under a few conditions (1) in pebbles which simulated a sediments of deep sea floor, (2) at the natural interface of methane gas and water and (3) with the forced stirring of gas and water. Formed hydrate was dissociated by means of depressurization and heating. The self-preservation effect was tested after maintaining at an atmospheric pressure and a lower temperature of freezing. The stability of the hydrate was confirmed by burning the dissociated methane gas. As the results some features were obtained. To expedite a quick forming of hydrate heat absorption as well as stirring of gas and water is essential. Either heating or depressurization is effective for dissociation but each presented different phenomena. Self-preservation effect could be improved by selecting a suitable freezing temperature.
A large volume of methane gas hydrate deposits is said to be distributed both on-shore and off-shore of the earth. This is considered as the potential resources of methane gas for a favorable energy to the earth environment. On the other hand the artificial coexistence of water and methane gas leads to the formation of gas hydrate. In this paper author carried out the experiments of a series of gas hydrate formation to dissociation including a confirmation of the self-preservation effect. Through these tests behaviors of gas hydrate was surveyed.
Test device consists of methane gas supply system, distilled water supply system, pressure cell, stirring system, cooling box and temperature and pressure control system as shown in Fig.1. Methane gas can be supplied either from the top region or from the bottom part for each test of water-gas interface or forced stirring of gas bubbles respectively.