Simulation of the Extraction Efficiency of Coalbed Methane under Water Injection: A Gas-Liquid-Solid Coupling Model

Table 2

Numerical model boundary conditions.

Coal seam deformation	Value	Fluid migration	Value
Upper boundary/MPa	14	Methane extraction pressure/kPa	20
Lower boundary	Fixed	Water injection pressure/MPa	2
Left boundary	Roller support	Initial water pressure/MPa	0
Right boundary		Initial methane pressure/MPa	2
Borehole boundary	Free	Water injection time/day	21
Initial displacement	0