Method of producing synthesis gas by underground gasification of coal using specific well configuration
First Claim
1. A method of producing synthesis gas by the underground gasification of coal in individual noninteracting cavities formed by the gasification of the coal in a thick coal seam which is generally horizontal under an overburden and wherein loose coal and char formed from the combustion of the coal in said seam have a known angle of repose, said seam being provided with an injection well positioned at an angle with respect to the horizontal of less than the angle of repose and with a production well positioned at an angle with respect to the horizontal of greater than the angle of repose but less than 90°
- , the distance between said wells decreasing toward the bottom of said seam, comprising linking said wells, initiating combustion near the bottom of said seam and thereby producing a cavity in said seam, introducing an oxygen-containing gas mixture into said seam through said injection well, and removing combustion products through said production well.
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Abstract
Underground coal gasification process containing a novel system of injection and production wells. Specifically, the injection well is positioned at an angle with respect to horizontal of less than the angle of repose of loose coal and char for the particular coal seam, and the production well is positioned at an angle with respect to horizontal of greater than the angle of repose but less than 90°. This system protects the injection well during the process and places the production well in a position for maximum production while relieving it of certain tensile and shear stresses.
16 Citations
11 Claims
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1. A method of producing synthesis gas by the underground gasification of coal in individual noninteracting cavities formed by the gasification of the coal in a thick coal seam which is generally horizontal under an overburden and wherein loose coal and char formed from the combustion of the coal in said seam have a known angle of repose, said seam being provided with an injection well positioned at an angle with respect to the horizontal of less than the angle of repose and with a production well positioned at an angle with respect to the horizontal of greater than the angle of repose but less than 90°
- , the distance between said wells decreasing toward the bottom of said seam, comprising linking said wells, initiating combustion near the bottom of said seam and thereby producing a cavity in said seam, introducing an oxygen-containing gas mixture into said seam through said injection well, and removing combustion products through said production well.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
Specification