METHOD OF CONNECTION OF BOREHOLES FOR UNDERGROUND GASIFICATION OF COAL Russian patent published in 1994 - IPC

FIELD: underground gasification of coals. SUBSTANCE: method of connection of boreholes consists in consecutive hydraulic fracture of coal seam, flushing of formed channel of hydraulic fracture and in its successive fire penetration. Novelty of method lies in flushing of channel of hydraulic fracture up to complete withdrawal of coal particles with water, in shutting off of borehole-drain, in increase of pressure in channel up to value equal or exceeding pressure of hydrostatic column of underground waters and in keeping of pressure in channel after lighting up of coal seam by partial opening of borehole-drain. EFFECT: enhanced efficiency and reliability of connection of boreholes by prevention of clogging of channels after coal seam hydraulic fracture is accomplished. 2 cl, 1 dwg