Gulf Research & Development Company

Richard H Graham

Robin R Oder

Shirley C Tsai

In the underground gasification of a swelling coal the high gas-flow link between the injection and the production wells needed for the gasification process is produced by reverse combustion using air heated to a temperature below the softening point of the coal. The heated air pretreats and conditions the coal proximate to the link under formation by increasing its permeability and reducing its swelling properties. Improved combustion and suppression of plugging results in the subsequent gasification stage.

Subterranean gasification of bituminous coal

In the underground gasification of a swelling coal the high gas-flow link between the injection and the production wells is produced by introducing hot air into the injection well at a pressure sufficient to fracture the coal. The bulk permeability of the coal proximate to the link is increased and the plugging of the link during the subsequent in situ combustion and gasification procedure is suppressed by continuing the injection of the hot air, heated to a temperature below the softening point of the coal, into the injection well, through the link to the production well without combustion of the coal.

Underground gasification of bituminous coal

In the underground gasification of a swelling coal the bulk permeability of the coal proximate to the linkage between the injection and the production holes is increased and the plugging of the linkage during the in situ combustion and gasification procedure is suppressed by subjecting this coal proximate to the linkage between the injection and production holes to a stream of air heated to a temperature below the softening point of the coal prior to the in situ combustion and gasification procedure.

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O'Hara Township, PA, United States of America

Richard H Graham