Water Infusion

Water infusion, the injection of water at high pressure (>7 Mpa), has been explored as a stress relief mechanism to prevent outbursts. The water pressure fractures the coal in advance of the face and provides for slow relaxation of stress through lateral movement enhanced by the presence of the water. However, the effectiveness of water infusion decreases as the depth of cover increases, owing to the reduction in coalbed permeability with depth. Other methods using the same principle include pulsed infusion shotfiring and hydrofraccing.