Palaeotectonic stress-fields and prediction of higher-permeability region for coalbed methane exploration in low-permeability coal reservoirs

Prediction of higher-permeability region for CBM(coalbed methane) exploration in the Huainan coalfield, where commonly occurs the low-permeability coal reservoirs, was finished by use of simulational results of the palaeotectonic stress-fields, combined with coalmine geological investigation, drilling-hole coal-core description during geological exploration and the permeability data from CBM test-holes.Comprehensive analysis shows that the area with high-stress value is well coincided with the distribution of tectonic coals.Tectonic coal caused by rheological strain is the important factor influencing permeability reducing in coal reservoirs.So that, the area with low-stress value is probably the target with higher-permeability coal beds in which the primary cleat (fracture) sets are continuously retained.