Method of initiating subterranean combustion

Claim 1

IN A METHOD OF RECOVERING PETROLEUM FROM A SUBTERRANEAN FORMATION HAVING AN INPUT WELL AND AN OUTPUT WELL LEADING FROM THE SURFACE THERETO WHEREIN SAID PETROLEUM IS IGNITED AT SAID INPUT WELL, A COMBUSTION SUPPORTING GAS IS FORCED THROUGH SAID INPUT WELL INTO SAID FORMATION TO MAINTAIN COMBUSTION OF PETROLEUM THEREIN, AND PETROLEUM AND COMBUSTION PRODUCTS MIGRATE TO SAID OUTPUT WELL, THE IMPROVEMENT IN INITIATING COMBUSTION OF PETROLEUM CONTAINED IN SAID FORMATION COMPRISING PLACING ADJACENT TO SAID FORMATION FOR THE ENTIRE DEPTH THEREOF AT SAID INPUT WELL A MIXTURE COMPRISING A GRANULAR, REFRACTORY SURFACE ACTIVE MATERIAL HAVING A SURFACE AREA BETWEEN 125 AND 325 SQUARE METERS PER GRAM AND A PARTICLE SIZE BETWEEN .004 AND 0.2 INCH IN EFFECTIVE DIAMETER AND HAVING DEPOSITED THEREIN PETROLEUM COKE IN AN AMOUNT BETWEEN ONE PERCENT AND FIFTEEN PERCENT BY WEIGHT OF SAID MIXTURE, AND FORCING SAID COMBUSTION SUPPORTING GAS THROUGH SAID INPUT WELL TO SAID MIXTURE AND INTO SAID FORMATION AND IGNITING SAID COMBUSTION MATERIAL IN SAID MIXTURE.