Evaluation of Coal Seam Gas Drainability for Outburst-Prone and High-CO₂-Containing Coal Seam

Table 3

Classification of coalbeds based on their permeability (after Ref. [45]).

In situ permeability (K)	Drainability
K ≤ 1 mD	No drainage
1 mD < K ≤ 5 mD	Difficult drainage
5 mD < K ≤ 9 mD	Low drainage
9 mD < K ≤ 50 mD	Successful drainage