Method of forward in situ combustion utilizing air-water injection mixtures

Claim 1

IN A PROCESS FOR THE RECOVERY OF HYDROCARBON FROM AN UNDERGROUND RESERVOIR BY MEANS OF COMBUSTION, SAID RESERVOIR BEING PENETRATED AT SPACED POINTS BY AN INJECTION WELL AND A PRODUCING WELL, THE IMPROVEMENT WHICH COMPRISES, INITIATING A ZONE OF COMBUSTION IN SAID RESERVOIR AT A POINT ADJACENT THE FACE OF SAID INJECTION WELL, SUBJECTING SAID RESERVOIR TO A FLUID PRESSURE OF FROM ABOUT 250 P.S.I. TO A PRESSURE JUST BELOW THAT REQUIRED TO FRACTURE SAID RESERVOIR, NEXT PROPAGATING SAID COMBUSTION ZONE TOWARD SAID PRODUCING WELL BY INJECTING A MIXTURE OF OXYGENCONTAINING GAS AND WATER IN WHICH A COMBINATION OF THE RATIO OF OXYGEN TO WATER AT THE PREVAILING RESERVOIR PRESSURE DEFINES A POINT FALLING SUBSTANTIALLY WITHIN THE SHADED AREA BETWEEN CURVES B AND C OF FIGURE 2, SUSTAINING SAID COMBUSTION ZONE BY VARYING THE OXYGEN REQUIREMENTS THEREFOR INVERSELY WITH SAID PRESSURE, WHEREBY THE STEAM THUS GENERATED IN SAID RESERVOIR IS ABOVE THE IGNITION TEMPERATURE OF SAID HYDROCARBON, AND THEREAFTER RECOVERING HYDROCARBON FROM SAID PRODUCING WELL.