OS3B-1:OVERVIEW ON PERMAFROST GAS HYDRATE EXPLORATION IN CHINA

Youhai ZHU¹, Yongqin ZHANG², Zhongjun SUN³

1. Oil and Gas Survey CGS; 2. Institute of Exploration Techniques CAGS; 3. Institute of Geophysical and Geochemical Exploration CAGS

China is the world’s third largest permafrost country where exist large continuous permafrost with an area of 2.15×10⁶ Km² in the Qinghai-Tibet Plateau and Da Hinggan Mountains. Preliminary survey results showed that Qinghai-Tibet plateau, Qilian Mountains and Mohe basin with better gas hydrate formation conditions are likely prospecting areas for gas hydrate.

Gas hydrates were found in the Qinlian Mountains permafrost in 2008, which occurred as the fracture-filling in the middle Jurassic coal-bearing formation, or as pore-filling in the porous of sandstone. In 2011, a test production of gas hydrate was successfully in the Qilian Mountain by depressurization and heating methods, and a total of 95m³ gas was producted from hydrate-bearing zones within 101 hours. On-site monitoring results showed that gas hydrate drilling and test producing processes didn’t impact on the surrounding environment, methane releases from surface soil and methane content of lower atmosphere didn’t change significantly. Currently, we are carrying out gas hydrate exploration in the Qinghai-Tibet Plateau and Mohe permafrost, striving to find more gas hydrates.