Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas-Bearing Coal

Table 1

Parameters used in numerical simulation [17].

Parameter	Value
Modulus of elasticity of coal	2713 MPa
Poisson’s ratio of coal	0.339
Initial porosity	0.072
Initial gas pressure	1.08 MPa
Initial coal permeability	0.02 mD
Coal initial diffusion coefficient	1 × 10^−12 m^2/s
Attenuation coefficient	2 × 10^−8 s^−1
Langmuir pressure constant	1.8672 MPa^−1
Langmuir volume constant	14.4348 m^3/t
Coal density	1250 kg/m^3
The molar mass of methane	0.016 kg/mol
Drainage time	360 d
Time step	1 d
Ambient temperature	293 K