An Improved Coupled Modeling Method for Coalbed Methane Extraction after Hydraulic Fracturing

Table 1

Parameters for numerical simulation.

Variable	Parameters	Value	Variable	Parameters	Value
	Young’s modulus/GPa	8.47		Increased coefficient of permeability	10
	Poisson’s ratio	0.23		Initial methane pressure in fracture/MPa	1.32
	Coal density/kg/m^3	1650		Initial methane pressure in matrix/MPa	1.32
	Ultimate tensile strength/MPa	0.10		Initial porosity for coal matrix	0.035
	Ultimate compressive strength/MPa	16.8		Initial porosity for fracture	0.018
	Internal friction angle/°	32		Coal matrix size/m	0.01
	Water injection pressure/MPa	10		Temperature of coal seam/K	300
	Initial fracture permeability in direction/m^2			Methane dynamic viscosity/pa·s
	Initial fracture permeability in direction/m^2			Adsorption time/s	153360
	Initial fracture permeability in direction/m^2			Langmuir pressure constant/MPa	0.93
	Initial matrix permeability/mD	0.002		Langmuir volume constant/m^3/kg	0.0371
	Extraction pressure/kPa	20		Langmuir strain constant	0.012
	Increased coefficient of porosity	10		Klinkenberg factor/MPa	0.76