Method for producing high viscosity oil

Claim 1

A PROCESS FOR PRODUCING VISCOUS CRUDE OIL FROM A SUBTERRANEAN OIL-CONTAINING FORMATION BY ENHANCING THE NATURAL FORMATON FORCES SUFFICIENTLY TO PRODUCE THE OIL INTO A PRODUCING WELL COMPRISING THE STEPS OF: (A) PROVIDING AN INJECTON WELL AND A PRODUCTION WELL IN HORIZONTALLY SPACED RELATIONSHIP PENETRATING THE OIL-CONTAINING FORMATION; (B) TREATING THE FORMATION TO CREATE A COMMUNICATION ZONE OF HIGHER PERMEABILITY THAN THE REMAINDER OF THE FORMATION BETWEEN THE INJECTION AND PRODUCTION WELLS; (C) INJECTING A BATCH OF A LIQUID SOLVENT THROUGH THE INJECTION WELL INTO THE COMMUNICATION ZONE UNTIL THE SOLVENT BREAKS THROUGH AT THE PRODUCTION WELL; (D) PRODUCING OIL FROM THE FORMATION THROUGH THE COMMUNICATION ZONE AND INTO THE PRODUCTION WELL UNTIL THE OIL PRODUCTION RATE DECREASES BELOW A DESIRED RATE AS A RESULT OF VISCOUS OIL PLUGGING THE COMMUNICATION ZONE; (E) INJECTING A FRESH BATCH OF THE SOLVENT INTO THE COMMUNICATION ZONE UNTIL FRESH SOLVENT BREAKS THROUGH AT THE PRODUCTION WELL AND REPEATING STEPS (D) AND (E) UNTIL THE NATURAL FORMATION FORCES AT THEIR INITIAL LEVEL ARE INSUFFICIENT IN MAGNITUDE TO PRODUCE THE VISCOUS OIL INTO THE PRODUCTION WELL AT A DESIRED RATE OF RECOVERY; (F) IGNITING THE HYDROCARBONS IN THE COMMUNICATION ZONE ADJACENT TO THE INJECTION WELL; (G) PASSING AN IN SITU COMBUSTION WAVE THROUGH THE COMMUNICATION ZONE BY SUPPLYING A COMBUSTION SUPPORTING GAS TO THE IGNITED HYDROCARBONS TO HEAT THE SURROUNDING FORMATION WHEREBY THE LEVEL OF THE NATURAL FORMATION FORCES FOR PRODUCING OIL IS INCREASED; (H) PRODUCING THE VISCOUS OIL FROM THE FORMATION THROUGH THE HEATED COMMUNICATION ZONE INTO THE PRODUCTION WELL AT THE INCREASED LEVEL BY REPEATING THE PRECEDING STEPS (D) AND (E); AND (I) REPEATING THE STEPS (F) THROUGH (H) UNTIL AN INCREASED LEVEL OF NATUREAL FORMATION FORCES FOR PRODUCING OIL IS OBTAINED WHICH PRODUCES THE DESIRED RECOVERY OF THE VISCOUS OIL FROM THE FORMATION.