Procedure of in-situ combustion for recovery of hydrocarbon material

Claim 1

A PROCESS FOR THE RECOVERY OF HYDROCARBON MATERIAL FROM A SUBTERRANEAN FORMATION CONTAINING A SOURCE MATERIAL THEREOF COMPRISING: PASSING A FIRST COMBUSTION FRONT BY REVERSE COMBUSTION THROUGH AT LEAST A PORTION OF SAID FORMATIN BETWEEN AN OUTPUT WELL AND AN INPT WELL BY IGNITING SAID SOURCE MATERIAL AT SAID OUTPUT WELL AND PASSING OXIDIZING FLUID THROUGH SAID FORMATIN TO SAID OUTPUT WELL FROM SAID INPUT WELL WHEREBY SAID COMBUSTION FRONT MIGRATES THROUGH SAID FORMATION IN A DIRECTION FROM SAID OUTPUT WELL TO SAID INPUT WELL AND FORMS A CARBONACEOUS RESIDUE WITHIN SAID FORMATION OVER THE PORTION THEREOF THROUGH WHICH SAID COMBUSTION FRONT MIGRATES AND A HEAT FRONT PRECEDES SAID COMBUSTION FRONT IN THE DIRECTION OF SAID INPUT WELL AND PRMITS LOW TEMPERATURE OXIDATION OF SAID SOURCE MATERIAL TO OCCUR WITHIN THE PORTION OF SAID FORMATION BETWEEN SAID COMBUSTON FRON T AND SAID INPUT WELL; PRODUCING HYDOCARBON MATERIAL FROM SAID OUTPUT WELL; DISCONTINUING PASSAGE OF SAID OXIDIZING FLUID THROUGH SAID FORMATION WHEN SAID COMBUSTION FRONT HAS MIGRATED A PORTION ONLY OF THE DISTANCE BETWEEN SAID OUTPUT WELL AND SAID INPUT WELL AND THE LEADING EDGE OF SAID HEAT FRONT REACHES SAID INPUT WELL SO THAT SAID FORMATION BETWEEN SAID OUTPT WELL AND SAID INPUT WELL WILL CONSIST OF A PORTION OVER WHICH SAID COMBUSTION FRONT HAS MIGRATED CONTAINING CARBONA-