Practical production test of natural gas hydrate in sea areas and its technological analysis

Natural gas hydrate is a kind of potential new clean energy resource that is concerned, and it is mostly existed in the submarine sedimentary layers with water depth over 300 m. Japan and China have applied successively deepwater drilling vessel and semi-submerged platform to the practical production test of natural gas hydrates in sea areas and have obtained some achievements.There are abundant natural gas hydrate reserves in the area of South China Sea. To deal with energy supply shortage and environmental problems, it is of great significance to explore effective methods and technologies and realize safe, stable and efficient commercial production. In this paper, domestic and foreign technologies were investigated, and natural gas hydrate exploitation methods were researched, such as pressure drop, heat injection and chemical injection. Then, based on the practical production test of natural gas hydrate in the area of Japan Sea, early preparation of production test, design criteria and difficulties, process program, key parts of production test system and the existing problems (e.g. gas-liquid separation efficiency, sand production and flow guarantee) were analyzed thoroughly.Finally, the optimization and improvement suggestions were proposed correspondingly. It provides the reference for the following design and construction of natural gas hydrate production test in the sea areas of China.