A Fully Coupled Hydromechanical Model for CO₂ Sequestration in Coal Seam: the Roles of Multiphase Flow and Gas Dynamic Diffusion on Fluid Transfer and Coal Behavior

Table 1

Parameters implemented in the simulator.

Valuable (parameter)	Value	Units
(initial CO2 diffusion coefficient)		m^2/s
(attenuation coefficient)		-
(temperature)	293	K
(density of coal)	1650	kg/m^3
(Langmuir volume constant)	0.045	m^3/kg
(Langmuir pressure constant)	0.6	MPa
(average distance between coal fractures)	0.005	m
(water residual saturation)	0.2	-
(gas residual saturation)	0.1	-
(the coefficient in Eq. (11))	0.65	-
(initial Young’s modulus of coal)	4	GPa
(Poisson’s ratio of coal with no overpressure)	0.285	-
(Langmuir strain constant)	0.03	-
(initial fracture porosity)	0.03	-
(initial permeability)		m/s
(porosity of coal matrix)	0.01	-
(initial water saturation)	0.6	-
(CO2 injection rate)		m^2/s
(water injection rate)		m^2/s