Method of treating a subterranean formation with a foam bank

Claim 1

IN THE METHOD OF TREATING A SUBTERRANEAN OIL-BEARING FORMATION WHEREIN A FOAM BANK IS DRIVEN THROUGH AT LEAST A PORTION OF SAID FORMATION, THE IMPROVEMENT WHICH COMPRISES GENERATING SAID FOAM BANK FROM A LIQUID DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF: (A) 25-40% OF A SULFATED AND NEUTRALIZED REACTION PRODUCT OBTAINED FROM (1) CONDENSING 1 TO 5 MOLES OF ETHYLENE OXIDE AND 1 MOLE OF MONOHYDRIC ALCOHOL OF FROM 10-16 CARBON ATOMS IN THE MOLECULE; (2) SULFATING THE CONDENSATION PRODUCT OF (1): (3) NEUTRALIZING THE SULFATED PRODUCT OF (2) WITH A NEUTRALIZING AGENT SELECTED FROM THE GROUP CONSISTING OF AMMONIA AND ALKYLOL-SUBSTITUTED AMMONIA HAVING FROM 2-3 CARBON ATOMS IN THE ALKYLOL GROUP; (B) AN ORGANIC BUILDER SUBSTANCE CONSISTING ESSENTIALLY OF ALKYLOL AMIDE OF SATURATED FATTY ACIDS HAVING 10, 12 AND 14 CARBON ATOMS AND AN ALKYLOL AMINE, SAID ALKYLOL AMIDE HAVING NOT MORE THAN 3 CARBON ATOMS IN EACH ALKYLOL RADICAL AND THE AMOUNT THEREOF BEING FROM 6 TO 12% OF THE COMPOSITION; (C) 15-25% OF ALCOHOL SELECTED FROM THE GROUP CONSISTING OF ETHANOL, NORMAL PROPANOL AND ISOPROPANOL;