METHOD form horizontal drainage systems for gas, a method of drilling a borehole DRAINAGE AND METHOD FOR PRODUCTION OF GAS from coal seams (optional)

摘要

A method for removing water and producing methane from a subterranean coal seam. The method includes drilling a first substantially vertical well bore to the depth of the target coal seam, enlarging the bore of the vertical well at the depth of a target coal seam to provide an enlarged cavity, drilling an offset well intersecting the cavity substantially horizontally and then drilling through the cavity in order to drill substantially horizontal drainage well bores in the coal seam. The method may be used as a pre-mining step in conjunction with subterranean mining of the coal seam in order to remove methane and other dangerous gases and excess water from the coal seam in advance of mining operations.