Method for recovering methane from coal seams
AssigneeAlgas Resources Ltd.
InventorDenes G. Masszi
Life of this patent
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Abstract
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.
Claims9
A process for recovering from an underground coal seam methane gas which occurs in adsorbed form in said coal seam, said process comprising providing a borehole which extends from the surface of the earth underground through overburden to a terminal point, providing at said terminal point an underground cavity at least partly in or immediately adjacent to said coal seam, said cavity being located such that the pressure of said overburden is greater than the crushing strength of said cavity, said cavity having a radius at least five times the radius of said borehole at said terminal point, said cavity being unsupported, non-self-protecting and, hence, collapsible and constructed and arranged such that under the influence of triaxial compression coal from said coal seam will move toward and into said cavity, thereby fracturing and converting methane gas adsorbed in the coal into methane gas in free form, and recovering said free form methane gas from said cavity via said borehole.
Dependencies are inferred from the claim text.