Development of Marine Natural Gas Hydrate Mining Technology and Equipment
Qiang Fu, Guorong Wang, Shouwei Zhou, Lin Zhong, Leizhen Wang
Abstract
Natural gas hydrate, especially marine natural gas hydrate, is a new clean unconventional energy which is expected to replace the traditional fossil energies. The global reserve for the natural gas hydrate is rich; but its exploitation is still in the research stage, and the commercial and large-scale exploitation faces many challenges regarding technology and equipment. Aimed at the existing hydrate exploitation methods, this study analyzes the key technologies and processes involved in two trial production modes (i.e., depressurization and solid-state fluidization) that were adopted in the pilot production projects of offshore natural gas in Japan and China, summarizes the development status of relevant technology and equipment in China and abroad, and proposes some development suggestions for marine gas hydrate exploitation suitable for the reservoir and equipment technology in China. We found that China lags behind other countries in the fields of general key technologies and equipment for hydrate, oil gas, and subsea metal mining, represented by deep-sea mining vehicles and dual-gradient drilling technology for the loose shallow layer. In the field of special key technologies and equipment, represented by sand control technology and equipment, pre-inclined directional drilling technology for shallow hydrate mining, and combined production of hydrate, free gas, and conventional natural gas, China’s comprehensive level is equivalent to the international advanced level, but it still cannot satisfy the requirements for commercial mining. The development of exploitation technologies and equipment for marine natural gas hydrates in China is expected to enter a leading stage in 2035, and an engineering equipment system for commercial development is expected to be established by then. To this end, we suggest that a research and development plan for marine natural gas hydrate exploitation technology and equipment should be formulated at the national level, so as to promote the commercial development of hydrates, and the research and application of special and general technologies and equipment for offshore non-diagenetic hydrate exploitation should be accelerated.