Numerical Simulation Research on Hydraulic Fracturing Promoting Coalbed Methane Extraction

Table 1

Numerical simulation parameters.

Variable	Parameter	Value	Unit	Acquisition approach	Remark
E	Young’s modulus of coal	2710	MPa	Experiments
	Poisson’s ratio	0.3		Experiments
Es	Young’s modulus of coal skeleton	9520	MPa	Experiments
αs	Adsorption strain factor	0.06	kg/m^3	Experiments
ρs	Density of coal skeleton	1380	kg/m^3	Experiments
φ0	Initial coalbed porosity	0.037		Experiments
P0	Initial pressure of coalbed	3.53	MPa	Field data
k0	Initial coalbed permeability	5.14 × 10^−16	m^2	Field data
	Dynamic viscosity coefficient of methane	1.84 × 10^−5	Pa·s	References	[18]
	Dynamic viscosity coefficient of water	1.01	mPa·s	References	[18]
αT	Thermal expansion coefficient	2.4 × 10^−5	1/K	References	[28]
VL	Langmuir volume constant	0.02	m^3/kg	Experiments
PL	Langmuir pressure constant	0.96	MPa	Experiments
d1	Langmuir pressure correction factor	0.07	MPa^−1	References	[28]
d2	Langmuir temperature correction factor	0.02	K^−1	References	[28]
Tt	Laboratory reference temperature	300	K	References	[28]
Cs	Specific heat capacity of the coal skeleton	1300	J/(kg·K)	References	[28]
	Specific heat capacity of gas	2550	J/(kg·K)	References	[28]
	Specific heat capacity of water	4200	J/(kg·K)	References
λs	Heat conductivity of coal skeleton	0.193	W/(m·K)	References	[28]
	Heat conductivity of gas	0.031	W/(m·K)	References	[28]
	Heat conductivity of water	0.598	W/(m·K)	References	[18]
qst	Isosteric heat of adsorption	33.4	J/mol	References	[28]
	Irreducible water saturation	0.05		References	[18]
	Irreducible gas saturation	0.05		References	[18]