Dynamic Secondary Borehole-Sealing Method for Gas Drainage Boreholes along the Coal Seam

Figure 11

Tightness and gas drainage effect for boreholes under different borehole-sealing materials and borehole-sealing techniques. (a) Positive pressure. (b) Suction pressure. (c) Gas concentration. (d) Gas flow rate.

(a)

(b)

(c)

(d)