Marine Gas Hydrate Simulation Study

Natural gas hydrate is a sort of new energy. As one of the most important areas in the gas hydrates research, simulation experiment is of great significance to promoting the exploration and exploitation of the natural gas hydrate, and to forcing the development of the hydrate technology. On the basis of the summarizing the latest research findings of the natural gas hydrate, it emphasized simulation experiment in the dynamics of formation and decomposition, saturation and gas storage of the gas hydrate in this paper.According to the CO₂ hydrates formation experiment, it clearly showed that the resistance detecting technology used to study of the formation of the hydrate was an effective means. The results of the experiment indicates that the induction time of the hydrate formation stepped down if one and the same water was used experiment and remained the pressure, temperature and other things unchanged in the formation. In other words, the memory effect of water in hydrates formation was confirmed. Otherwise, due to the change of the ion concentration of the pore water, the resistance of the reaction system was caused to change. According to the change of the resistance and temperature, the hydrate formation process can be divided into five stages. Finally, a theoretical model for CO₂ hydrate nucleation rate was built up by analyzing the influence factor of the resistance of the reaction system, and combined with the specific reaction conditions, the variation trend of nucleation rate was obtained.By means of the resistance detecting technology and the Archie's law in the hydrate saturation simulation experiment, a theoretical model was built up to calculate the CO₂ hydrate saturation by the resistance of the porous medium. In succession, the CO₂ hydrate saturation in the formation was obtained by the experimental data applied to the model.Using self-designed simulation experiment device, the methane hydrate decomposition process was monitored under two dissociation methods, which were isovolumetric dissociation and normal pressure dissociation in porous medium of different particle size. In the methane hydrate isovolumetric dissociation experiment, the temperature and the pressure in the reactor experienced three different stages and there was a good functional relation between them. In addition, it was found that the dissociation of methane hydrate began on the gas-solid phase interface. Compared with the pure aqueous solution, the porous medium increased the gas-solid phase interface and the gas hydrate dissociation became easy. Hydrate formation would change the pore space of the porous medium, so that hydrate unequally was distributed in the system. In similar particle size porous medium system, the hydrate dissociation rate showed random.The hydrate gas storage experiment is proposed to investigate the characteristic of gas storage in methane hydrate. Based on the small-vessel which is designed to be opened easily so that the synthesized hydrate samples can be taken out conveniently for direct gas storage determination, we have synthesized a series different methane hydrates under various conditions in different systems (i.e. SDS+CH₄, ice powder+CH₄ and ice powder+ sediments+CH₄), respectively. The gas storages of these methane hydrates were measured using volumetric method while the hydrate samples decomposed in a vacuum system. The effects of reaction time, pressure and environmental medium on gas storage capacity of clathrate were discussed.