Patent ID: 6328104
Filing Date: 2001-12-11
Classification: E21B

Abstract:
A process for continuously converting, upgrading, and recovering heavy hydrocarbons from a subsurface formation, said process being free of in situ combustion operations (i.e., free from the injection of hot oxidizing fluids into said subsurface formation for the purpose of igniting a portion of said heavy hydrocarbons) and being free of injection of catalysts into the subsurface formation, and said process comprising the steps of:a. inserting a downhole combustion unit into at least one vertical injection borehole which communicates with at least one production borehole by means of multiple, uncased, horizontal boreholes extending from the injection and production boreholes, said downhole combustion unit being placed at a position within said injection borehole in proximity to said subsurface formation;b. flowing from the surface to said downhole combustion unit within said injection borehole a set of fluids--comprised of steam, reducing gases, and oxidizing gases--and burning at least a portion of said reducing gases with said oxidizing gases in said downhole combustion unit;c. injecting a gas mixture--comprised of combustion products from the burning of said reducing gases with said oxidizing gases, residual reducing gases, and steam--from said downhole combustion unit into said subsurface formation;d. recovering from said production borehole, production fluids comprised of said heavy hydrocarbons, which may be converted to lighter hydrocarbons, as well as residual reducing gases, and other components;e. continuing steps b, c, and d until the recovery rate of said heavy hydrocarbons within said subsurface formation in the region between said injection borehole and said production borehole is reduced below a level of practical operation.