Abstract:

Coalbed methane (CBM) resources in the Junggar Basin, Xinjiang, China are abundant. The most favorable targets
for CBM resources occur in the southern Junggar Basin, with stable and thick coal seams, shallow buried depth and higher CBM
content. The lack of geological knowledge of CBM accumulation and generation is the reason why the exploration in the region
had not achieved for many years. Based on the analysis of CBM accumulating conditions, it was considered that the favorable
geological controls of CBM accumulation occur in southern Junggar with the higher coal rank, the better hydrological conditions
and the abundant gas supply including the secondary biogenic gas and pyrolzed deep gas. CBM content is low in eastern Junggar
because of the lower coal rank, higher groundwater mineralization and the poor CBM preservation. On the basis of the analysis
abovementioned, it was suggested that the key geological controls of CBM accumulation in the southern Junggar are the structure,
hydrology and cap-rock. Favorable structural positions could control the pyrolyed deep gas supply. The hydrogeological conditions
might be favorable of secondary biogenic gas generation. The favorable cap rocks could make CBM to be preserved.