Method of underground gasification of a series of gently dipping and inclined coal seams

摘要

A method of underground gasification of a series of gently dipping and inclined coal seams comprises the steps of determining the depth of occurrence and the thickness of each coal seam in said series thereof, opening the seams by drilling operating wells, interconnecting them within the given seam, setting the coal afire, and gasifying the seams. A safe mining depth is determined for each coal seam in the series and said series of the seams is gasified upwards when a rock thickness therebetween exceeds a safe mining depth for the underlying seam and downwards when the rock thickness therebetween exceeds said safe depth, a firing boundary of the underlying seam being shifted towards a coal pillar by an amount equal to or greater than a first spacing of rock caving in the roof of a gasified layer.