Abstract: Disclosed is a process for controlling subsidence during underground gasification of coal. Prior to the complete coal gasification step, holes are provided extending from the bottom to the top of the coal seam and these holes filled with heat resistant support material. Thereafter, the complete gasification process is carried out.

Abstract: Use of an air-blown underground coal gasification plant to produce low-Btu gas thereby providing boiler fuel needed for an oxygen-blown underground coal gasification plant. The product from the oxygen-blown plant can be used for the production of synthetic natural gas or other uses. A preferred production gasification is also shown.

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.degree.. 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.

Abstract: Disclosed is a method for removing phenols from an underground gasification zone by injecting an alkaline material to convert at least a portion of the phenols to the corresponding salt and producing the solution of said salt. Thereafter, the salt can be converted to the free phenol or merely evaporated to dryness. In both of these cases, the phenol or salt can be incinerated.