Gas Hydrate Drilling Technology and Application Research in Wu-li Qinghai South Permafrost Region/LI Xiao-yang, ZHANG Yong-qin, SUN Jian-hua, LIANG Jian, WANG Han-bao, LI Xin-miao, WU Ji-xiu, LI Kuan, YIN Hao (The Institute of Exploration Techniques, CAGS, Langfang Hebei 065000, China) Abstract: Based on the introduction of the present situation of exploration and development of permafrost gas hydrates in the world and aiming at exploration requirements of gas hydrate in permafrost region of southern Qinghai, the hole structure of TK-2 is designed and large diameter wire-line coring and mud cooling technologies are used. Moreover, the problems of hole enlarging caused by permafrost melting and mud-cover in the inner wall of drill stem are emphatically discussed with effective solutions being adopted. The field experiment shows that key technologies of TK-2 are feasible. The meterage per rig-month is 702.07 m, the average core recovery rate reaches 93.5% and core bubbling and combustion-supporting are found at the depth of 229～234m.