Abstract:

The gas hydrate-discovering area in Muli of Tianjun, Qinghai Province was chosen as the research area, and the gas hydrate-discovering well was chosen as the analog model in this test to study the applicability of the microbial geochemical exploration (MGCE) method in gas hydrate exploration. Two different sampling grids of 250 m×500 m and 100 m×100 m were used in this study. The results showed that the research area had significant microbial anomaly, indicating the presence of hydrocarbon enrichment. The sparse grid study showed a favorable area of hydrocarbon enrichment, and the tight grid investigation showed the detail distribution of gas hydrate. This result verified the previous research result. The source of gas hydrates in the research area were also studied using geochemical method, and the results showed a very complex source, mainly thermogenic coalbed gas and oil-formed gas. This microbial geochemical exploration result can describe the detailed characteristics of the gas hydrate distribution and gas sources. Using geomicrobial, geochemical, geology and geophysical analysis (‘4G’), it can provide a new research method for the identification of gas hydrates in permafrost, and reduce the exploration risk and improve the success rate of exploration.

Key words: gas hydrate, microbial geochemical exploration, permafrost zone, Muli of Tianjun