Tertiary oil recovery process involving multiple cycles of gas-water injection after surfactant flood

Claim 2

IN A METHOD FOR RECOVERING PETROLEUM FROM A SUBTERRANEAN, PETROLEUM CONTAINING PORUS FORMATION PENETRATED BY AT LEAST ONE INJECTION WELL AND AT LEAST ONE PRODUCTION WELL, BOTH WELLS BEING IN FLUID COMMUNICATION WITH THE FORMATION SAID RECOVERY METHOD BEING OF THE TYPE WHEREIN AN AQUEOUS SURFACTANT SOLUTION IS INJECTED INTO THE FORMATION AND AN AQUEOUS SOLUTION OF HYDROPHILICC, VISOCITY INCREASING POLYMER IS INJECTED INTO THE FORMATION FOLLOWING THE SURFACTAT SOLUTION AND OIL DISPLACED BY THE INJECTED FLUIDS IS RECOVERED FROM THE FORMATION VIA THE PRODUCTION WELL, WHEREIN THE IMPROVEMENT COMPRISES: A. INJECTING FROM ABOUT 2 TO ABOUT 8 SLUGS OF GAS THE VOLUME OF WHICH IS FROM ABOUT 0.2 TO ABOUT 20.0 PORE VOLUME PERCENT WITH A SLUG OF FROM ABOUT 5 TO ABOUT 50 PORE VOLUME PERCENT WATER INJECTED BETWEEN SUCCEEDING GAS SLUGS INTO THE FORMATION AFTER INJECTION OF THE SOLUTION OF THE HYDROPHILIC VISCOSITY INCREASING POLYMER; AND B. INJECTING WATER INTO THE FORMATION AFTER INJECTION OF ALL OF THE SLUGS OF GAS TO DISPLACE THE GAS, SURFACTANT SOLUTION AND SOLUTION OF HYDROPHILIC VISCOSITY INCREASING BUFFER AND FORMATION PETROLEUM TOWARD THE PRODUCTION WELL.

Claim 3

A method as recited in claim 1 wherein the gas injected into the formation is selected from the group consisting of air, nitrogen, carbon dioxide, flue gas, engine exhaust gas, methane, ethane, propane, butane, ethylene, propylene, butylene, natural gas, liquefied petroleum gas, and mixtures thereof.

Claim 4

A method as recited in claim 2 wherein the gas is air.

Claim 5

A method as recited in claim 2 wherein the gas is nitrogen.

Claim 6

A method as recited in claim 2 wherein the gas is carbon dioxide.

Claim 7

A method as recited in claim 2 wherein the gas is methane.

Claim 8

A method as recited in claim 2 wherein the gas is natural gas.

Claim 9

A method as recited in claim 2 wherein the gas is liquefied petroleum gas.

Claim 10

In a method of recovering petroleum from a subterranean, porous, petroleum containing formation penetrated by at least one injection well having at least two separate injection paths from the surface of the earth to the petroleum containing formation, one being in fluid communication with the upper portion of the formation and one being in fluid communication with the lower portion of the formation, and at least one production well, said recovery method being of the type wherein a surfactant containing recovery fluid is injected into the formation via the injection well and fluids including formation petroleum are recovered from the production well, the improvement which comprises: simultaneously injecting into the formation, gas via the injection path in fluid communication with the lower portion of the formation and water via the injection path in fluid communication with the upper portion of the formation, both the gas and water being injected after injection of the surfactant containing fluid is completed, the ratio of gas volume flow rate to water flow rate being from about 0.002 to about 1.5, said gas being selected from the group consisting of air, nitrogen, carbon dioxide, flue gas, exhaust gas, methane, ethane, propane, butane, ethylene, propylene, butylene, natural gas, liquefied petroleum gas, and mixtures thereof.

Claim 11

In a method of recovering petroleum from a subterranean, porous, petroleum containing formation penetrated by at least one injection well having at least two separate injection paths from the surface of the earth to the petroleum containing formation, one being in fluid communication with the upper portion of the formation and one being in fluid communication with the lower portion of the formation, and at least one production well, said recovery method being of the type wherein a surfactant containing recovery fluid is injected into the formation via the injection well and fluids including formation petroleum are recovered from the production well, the improvement which comprises: simultaneously injecting into the formation, gas via the injection path in fluid communication with the lower portion of the formation and water via the injection path in fluid communication with the upper portion of the formation, both the gas and water being injected after injection of the surfactant containing fluid is completed, the ratio of gas volume flow rate to water flow rate being from about 0.002 to about 1.5, said gas being selected from the group consisting of air, nitrogen, carbon dioxide, flue gas, exhaust gas, methane, ethane, propane, butane, ethylene, propylene, butylene, natural gas, liquefied petroleum gas, and mixtures thereof.