Secondary recovery method with surfactant in fracturing fluid

Claim 1

IN THE COMBINATION PROCESS OF FRACTURING AND PRODUCING A SUBTERRANEAN OIL-BEARING FORMATION PENETRATED BY AT LEAST AN INJECTION WELL AND A PRODUCTION WELL WHEREIN THE FORMATION AT LEAST ADJACENT SAID INJECTION WELL IS FRACTURED BY THE INJECTION OF FRACTURING LIQUIDS INTO SAID FORMATION AT FRACTURING PRESSURES PRIOR TO THE INJECTION OF DRIVING FLUIDS INTO SAID INJECTION WELL AND SAID DRIVING FLUIDS ARE THEN DRIVEN THROUGH SAID FORMATION, THE IMPROVEMENT WHICH COMPRISES MIXING A SURFACTANT WITH SAID FRACTURING LIQUID PRIOR TO IT INJECTION, SAID SURFACTANT BEING IN A FORM WHICH WILL PERMIT DISPERSION THEREOF IN SAID FORMATION A DISTANCE AWAY FROM THE IMMEDIATE INJECTION WELL BORE VICINITY AND BEING CAPABLE UPON DISPERSION OF FORMING A TENACIOUS FOAM UNDR FORMATION CONDITIONS WHEN INTIMATELY CONTACTED WITH A LIQUID AND A GAS, FORMING A FOAM IN SAID FORMATION AND THEREAFTER INSTITUTING THE INJEXTION OF SAID DRIVING FLUIDS AND RECOVERING OIL-CONTAINING FLUIDS FROM SAID PRODUCTION WELL.