Underground linkage of wells for production of coal in situ

A method of linking two spaced apart production wells drilled through an underground coal seam wherein the linkage is accomplished substantially at the bottom of the underground coal seam in preparation for producing the coal in situ, comprising the steps of

• establishing a hermetic seal in each of the spaced apart production wells, the hermetic seal being between the underground coal seam and the surface of the earth,
• establishing an oxidizer injection conduit from the surface of the earth through an emplaced whipstock located at the bottom of a first production well,
• aligning the oxidizer injection conduit emerging from the whipstock toward a second production well, the emerging oxidizer injection conduit being positioned substantially at the bottom of the underground coal seam, and the emerging oxidizer injection conduit being aligned substantially parallel to the interface between the underground coal and the underburden,
• establishing an oxidizer injection conduit from the surface of the earth through an emplaced whipstock located at the bottom of the second production well,
• aligning the oxidizer injection conduit emerging from the whipstock in the second wall toward the first production well, the emerging oxidizer injection conduit being positioned substantially at the bottom of the underground coal seam, and the emerging oxidizer injection conduit being aligned substantially parallel to the interface between the underground coal and the underburden,
• igniting the coal seam in the first production well,
• igniting the coal seam in the second production well,
• injecting an oxidizer through the oxidizer injection conduit in the first production well with the resultant burning of a first channel in the path of the oxidizer blast,
• injecting an oxidizer through the oxidizer injection conduit in the second production well with the resultant burning of a second channel in the path of the oxidizer blast,
• inserting additional length of oxidizer injection conduit into the first production well with the resultant movement of the oxidizer release point moving in consonance with the retreating burning face of the first channel through the underground coal,
• inserting additional length of oxidizer injection conduit into the second production well with the resultant movement of the oxidizer release point moving in consonance with the retreating burning face of the second channel through the underground coal,
• continuing injection of the oxidizer into the first well and into the second well until the channel in the first well merges with the channel in the second well.