Research Article

Permeability Prediction in Deep Coal Seam: A Case Study on the No. 3 Coal Seam of the Southern Qinshui Basin in China

Table 1

Parameter magnitudes for matching the experimental data.

ParameterValue

Elastic modulus, (GPa)1.12
Poisson’s ratio, 0.26
Bulk modulus, (MPa)778
Matrix modulus, (MPa)10340
Constrained axial modulus, (MPa)1369
Biot’s coefficient, 0.925
Initial porosity (for N2), (%)0.585
Initial porosity (for CO2), (%)0.42
Maximum sorption volume (for N2), (m3/t)30.05
Langmuir parameter (for N2), (MPa−1)0.07
Sorption swelling coefficient (for N2), (t/m3)4.99 × 10−4
Langmuir volume (for CO2), (m3/t)55.78
Sorption parameter (for CO2), (MPa−1)0.48
Sorption swelling coefficient (for CO2), (t/m3)9.30 × 10−4
Effective coal matrix deformation factor, 0.1723
Empirical parameter for P-M model, 0.1
Matrix compressibility, (MPa−1)9.67 × 10−5
Fracture compressibility, (MPa−1)0.013
Initial fracture compressibility, (MPa−1)0.3422
Decline rate of fracture compressibility with increasing effective stress, (MPa−1)2.65 × 10−14