RECOVERY OF HEAVY HYDROCARBONS BY IN-SITU HYDROVISBREAKING

A process is disclosed for the in-situ conversion and recovery of heavy crud e oils and natural bitumens from subsurface formations (27) using either a continuous operation with one or more injection and production boreholes (21 ), which may include horizontal boreholes (21), or a cyclic operation whereby both injection and production occurs in the same boreholes (21). A mixture o f reducing gases, oxidizing gases, and steam are fed to the downhole combustio n device (206) located in the injection boreholes (21). Combustion of the reducing gas-oxidizing gas mixture is carried out to produce superheated ste am and hot reducing gases for injection into the formation to convert and upgra de the heavy crude or bitumen into lighter hydrocarbons. Communication between boreholes (21) is induced by fracturing. Injection wells may be cyclically operated where wellhead pressure is reduced and hydrocarbons in the vicinity of the boreholes (21) are produced, or continuously injected to drive hydrocarbons to the production boreholes (21) for recovery. In both operations, the hydrocarbons produced are collected at the surface for furth er processing.