Huff and puff fire flood process

Claim 1

A PROCESS FOR PRODUCING OIL FROM A SUBTERRANEAN STRATUM BEARING A RELATIVELY VISCOUS CRUDE OIL AND PENETRATED BY A PRODUCING WELL AND A PLURALITY OF OFFSET WELLS WHICH COMPRISES THE STEPS OF: (A) INJECTING AIR THRU SAID PRODUCTION WELL INTO SAID STRSATUM AT SUBSTANTIALLY HIGHER PRESSURE THAN THE PRESSURE THEREIN ADJACENT SAID PRODUCTION WELL; (B) IGNITING SAID STRATUM WITHIN SAID PRODUCTION WELL TO ESTABLISH A COMBUSTION ZONE AROUND SAID PRODUCTION WELL; (C) THEREAFTER, CONTINUING AIR INJECTION AS IN STEP (A) SO AS TO MOVE THE COMBUSTION ZONE OF STEP (B) INTO SAID STRATUM UNTIL PLUGGING SAID STRATUM BY MOBILE VISCOUS OIL FROM THE HEATED AREA OF THE STRATUM IS EFFECTED AND SUBSTANTIAL PRESSURE IS BUILT UP THEREIN (D) THEREAFTER, DISCONTINUING THE AIR INJECTION OF STEP (C) AND OPENING SAID PRODUCTION WELL TO PRODUCTION SO THAT COMPRESSED GASES WITHIN THE STRATUM RADIALLY REMOTE FROM SAID PRODUCTION WELL AND BEYOND THE PLUGGED AREA EXPAND AND FLOW TOWARD SAID PRODUCTION WELL, THEREBY DRIVING FLUID OIL INTO THE HOT BURNED-OVER AREA BETWEEN THE PLUGGED AREA AND SAID PRODUCTION WELL WHEREIN SAID FLUID OIL IS SUBSTANTIALLY HEATED AND UPGRADED AND RESULTING UPGRADED OIL IS FORCED INTO SAID PRODUCTION WELL; (E) MAINTAINING SAID OFFSET WELLS SHUT IN DURING STEPS (A) THROUGH (D) TO ASSIST PRESSURE BUILD-UP AND OIL PRODUCTION IN SAID PRODUCTION WELL; AND (F) RECOVERING OIL OF STEP (D) FROM SAID WELL.