Research and application of the natural gas hydrate drilling technique in Qilian Mountain permafrost

Large quantities of research and drilling sampling work shows that gas hydrates(GH) exist not only in the deep ocean but also in the permafrost zone. Viewed from the development status of the geological exploration, the determination of the storage depth, content and other physical and chemical properties of the GH has to depend on the drilling technique. The global research status of the GH in the permafrost is expounded and the drilling tool design and manufacture process and research achievements of the GH at 4200m above the sea level are described in this paper.