摘要 |
Methane is recovered from an underground coal seam via a borehole which extends from the earth's surface through the overburden to a cavity that is in, partly in or proximate to the coal seam. The cavity is constructed and arranged to be collapsible. Coal from the coal seam moves toward the coal seam under the influence of triaxial compression converting adsorbed methane to free form methane that is recovered. |