SITU COAL BED GASIFICATION

摘要

Deeply buried relatively thick coal bed formations are fractured explosively. Reactant input conduits communicating with upper portions of the fragmented coal zone and product withdrawal conduits communicating with lower portions thereof are provided. The uppermost layer of the fragmented zone is ignited as by injection of oxygen and fuel gas from a surface plant while the product conduits are closed off to raise the operating pressure in the fragmented zone to balance hydrostatic pressure so that the fragmented zone comprises effectively a pressurized reaction vessel. Water or steam together with regulated amounts of oxygen are then introduced while reaction products are withdrawn at a rate at which operating pressure is maintained so that a relatively higher temperature reaction zone layer is reacted in the upper layer to travel progressively downward. A graduated lower temperature region precedes the higher temperature zone. Various gasification reactions occur in the reaction zones with the net overall products being methane and CO2 with relatively little up to varying amounts of carbon monoxide and hydrogen appearing in the reaction product gas. Processing to remove CO2 and react the carbon monoxide and hydrogen if deemed necessary is done at the surface yielding a high caloric value fuel gas suitable for pipeline or for synthesis uses.