Standard Oil Company (indiana)

Amoco Corporation

David R Parrish

Bruce W Gash

Luis E Arri

Elton B Hunt, Jr

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.

Method of producing synthesis gas by underground gasification of coal

Depleted zones or channels in in situ retorts that bypass unretorted zones can be plugged selectively by contacting the depleted zones in the in situ oil shale retort with an aqueous liquid, substantially free of a formation plugging amount of a solute, to increase the resistance of the depleted zone or channel to the passage of retorting gases.

Method for selective plugging of depleted channels or zones in in situ

Disclosed is a method and apparatus for the enhanced recovery of liquid hydrocarbons from underground formations, said method comprising recovering a mixture comprising carbon dioxide and contaminants comprising hydrocarbon, hydrogen sulfide, or mixtures thereof, from an underground formation; combusting said mixture with an oxygen enriched gas to form a concentrated carbon dioxide stream; and injecting at least a portion of said concentrated carbon dioxide stream into an underground formation to enhance recovery of liquid hydrocarbon.

Method for enhanced oil recovery

A method for tracing the flow of a plurality of fluid slugs injected into a subsurface formation using a number of tracers smaller than the number of fluid slugs. Single tracers are used in a number of fluid slugs equal to the number of tracers. In the remaining injected fluid slugs, combinations of at least two of the tracers in predetermined concentration ratios are used. Recovered fluid is analyzed for the presence of each of the tracers and the ratios of the tracers indicates breakthrough of each injected slug.

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Tulsa, OK, United States of America

David R Parrish