Abstract:

Turning towards the geological complex conditions of coalbed methane (CBM) in Panxian, western Guizhou, the tectonic
control of the CBM reservoir was discussed taking the tectonic evolution as a basic approach and combining with the geological
field observation and the lab analysis. Results showed that four tectonic stages in the area have be experienced including the
intra-continental rift stage from Devonian to Permian, stable platform stage from Early to Middle Triassic, continental depression
stage from Late Triassic to Middle Jurassic and fault-folded uplift stage form Late Jurassic to Quaternary. Coal seams occur in
the synclines indicating an obvious syncline control of CBM resources. The Late Permian coal-bearing strata were characterized
by two periods of subside burials, two periods of uplift erosions and three periods of coalifications. Middle Yanshanian tectonic
movement was a key period to CBM reservoiring, in which the modern occurrence of the coal rank was built by the telemagmatic
metamorphism on the deep burial metamorphism setting. High CBM content in the area is caused importantly by the compressive
and compressive-shear structures. Modern tectonic stress field with the nearly east-west direction of horizontal compression might
make the coal seam permeability in the Tucheng and Zhaozihe synclines higher than that in the Panguan and Jiupuan synclines.