Attribute Synthetic Evaluation Model for the CBM Recoverability and Its Application

Table 2

Recoverability evaluation indexes of CBM and its grades.

Evaluation indexes	Recoverability grades
	Bad	Comparatively bad	Moderate	Comparatively good	Good
Seam thickness (m)	<4	4~5	5~6	6~8	>8
Gas saturation (m^3/t)	<8	8~10	10~15	15~20	>20
Original seam permeability (10^−3 μm^2)	<0.3	0.3~0.5	0.5~1	1~5	>5
Reservoir pressure gradient (Mpa/100)	<0.4	0.4~0.6	0.6~0.8	0.8~1.0	>1.0
Hydrogeological conditions	1	2	3	4	5