Study on the Mechanism of Liquid Carbon Dioxide Fracturing and Permeability Enhancement Technology in Low Permeability Thick Coal Seam

Table 1

Basic parameters of liquid carbon dioxide fracturing model for No. 2 coal seam.

Physical parameter	Units	Value
Adsorption constant	m^3/t	29.24
Adsorption constant	MPa^-1	0.95
Drainage negative pressure	kPa	20
Coal seam gas pressure	MPa	0.2
Coal seam gas pressure	MPa	0.2
Klinkenberg coefficient	MPa	0.35
Coal seam cohesion	MPa	1.5
Atmosphere	MPa	0.101325
Roof cohesion	MPa	3.5
Floor cohesion	MPa	4.8
Roof elastic modulus	GPa	5.0
Elastic modulus of base plate	GPa	6.5
Elastic modulus of coal seam	GPa	3.0
Water proportion	%	0.44
Dust proportion	%	8.07
Volatile proportion	%	17.38
Porosity	%	4.3
Maximum adsorption volume expansion	%	3
Coal density	kg/m^3	1400
Density of floor	kg/m^3	2600
Roof density	kg/m^3	2300
Internal friction angle of floor	/°	37
Roof internal friction angle	/°	32
Internal friction angle of coal	/°	25
Gas universality coefficient	J/(mol·K)	8.314
Initial permeability of coal seam	m^2
Poisson’s ratio of coal seam	—	0.35
Dynamic viscosity	Pa·s