High conformance oil recovery process

Claim 1

A method of recovering petroleum from a subterranean, petroleum-containing formation, the temperature of said formation being not greater than 150° F., said formation containing water whose salinity is from 10,000 to 200,000 parts per million total dissolved solids, said formation containing at least two distinct petroleum-containing strata or layers, the permeability of at least one of said strata being at least 50 percent greater than the permeability of the other stratum, said formation being penetrated by at least one injection well and by at least one production well, both wells being in fluid communication with at least two of said formation strata, comprising (a) injecting a first aqueous oil-displacing fluid into the formation via the injection well, said fluid passing through at least one of the more permeable strata of said formation and displacing oil therein toward the production well, from which it is recovered to the surface of the earth; (b) after said first aqueous oil displacing fluid has passed substantially through at least one of said more permeable strata to the production well, discontinuing injecting said fluid and injecting into said stratum an aqueous emulsifying fluid containing an emulsifying surfactant combination comprising (1) from 0.01 to 10.0 percent by weight of an alkylpolyalkoxy sulfate or alkylarylpolyalkoxy sulfate having the following formula: RO(R'O).sub.n SO.sub.3 M wherein R is an alkyl group, linear or branched, having from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene and xylene having attached thereto at least one alkyl group, linear or branched, having from 9 to 15 carbon atoms; R' is ethylene or a mixture of ethylene and higher molecular weight alkylene with relatively more ethylene than higher alkylene; n is a number including fractional numbers, from 2 to 10; and M is a monovalent cation selected from the group consisting of sodium, potassium, lithium and ammonium, and (2) from about 0.1 to about 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R.sub.a (OR.sub.a ').sub.na OH wherein R a is a branched or linear alkyl group, containing from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene or xylene having attached thereto at least one alkyl group, linear or branched, containing from 9 to 15 carbon atoms, R a ' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and na is a number either whole or fractional, from 1 to 10, said emulsifying surfactants forming a macroemulsion in the more permeable strata of the formation, thereby reducing the permeability of the strata invaded by the emulsifying fluid; and (c) thereafter injecting a second aqueous oil displacing fluid into the formation; said fluid invading at least one stratum not invaded by the first oil displacing fluid of step (a) and displacing oil therein toward the production well where it is recovered to the surface of the earth.

Claim 2

A method of recovering petroleum from a subterranean, petroleum-containing formation, the temperature of said formation being not greater than 150° F., said formation containing water whose salinity is from 10,000 to 200,000 parts per million total dissolved solids, said formation containing at least two distinct petroleum-containing strata or layers, the permeability of at least one of said strata being at least 50 percent greater than the permeability of the other stratum, said formation being penetrated by at least one injection well and by at least one production well, both wells being in fluid communication with at least two of said formation strata, comprising (a) injecting a first aqueous oil-displacing fluid into the formation via the injection well, said fluid passing through at least one of the more permeable strata of said formation and displacing oil therein toward the production well, from which it is recovered to the surface of the earth; (b) after said first aqueous oil displacing fluid has passed substantially through at least one of said more permeable strata to the production well, discontinuing injecting said fluid and injecting into said stratum an aqueous emulsifying fluid containing an emulsifying surfactant combination comprising (1) from 0.01 to 10.0 percent by weight of an alkylpolyalkoxy sulfate or alkylarylpolyalkoxy sulfate having the following formula: RO(R'O).sub.n SO.sub.3 M wherein R is an alkyl group, linear or branched, having from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene and xylene having attached thereto at least one alkyl group, linear or branched, having from 9 to 15 carbon atoms; R' is ethylene or a mixture of ethylene and higher molecular weight alkylene with relatively more ethylene than higher alkylene; n is a number including fractional numbers, from 2 to 10; and M is a monovalent cation selected from the group consisting of sodium, potassium, lithium and ammonium, and (2) from about 0.1 to about 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R.sub.a (OR.sub.a ').sub.na OH wherein R a is a branched or linear alkyl group, containing from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene or xylene having attached thereto at least one alkyl group, linear or branched, containing from 9 to 15 carbon atoms, R a ' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and na is a number either whole or fractional, from 1 to 10, said emulsifying surfactants forming a macroemulsion in the more permeable strata of the formation, thereby reducing the permeability of the strata invaded by the emulsifying fluid; and (c) thereafter injecting a second aqueous oil displacing fluid into the formation; said fluid invading at least one stratum not invaded by the first oil displacing fluid of step (a) and displacing oil therein toward the production well where it is recovered to the surface of the earth.

Claim 17

A method of recovering petroleum from a subterranean, petroleum-containing formation, the temperature of said formation being not greater than 150° F., said formation containing water whose salinity is from 10,000 to 200,000 parts per million total dissolved solids, said formation containing at least two distinct petroleum-containing strata or layers, the permeability of at least one of said strata being at least 50 percent greater than the permeability of the other stratum, said formation being penetrated by at least one injection well and by at least one production well, both wells being in fluid communication with at least two of said formation strata, comprising (a) injecting a first fluid comprising an aqueous oil-displacing fluid into the formation via the injection well, said fluid passing through at least one of the more permeable strata of said formation and displacing oil therein toward the production well, from which it is recovered to the surface of the earth; (b) after said first aqueous oil displacing fluid has passed substantially through at least one of said more permeable strata to the production well, discontinuing injecting said first fluid and injecting into said stratum a second aqueous fluid containing from 0.01 to 10.0 percent by weight of an alkylpolyalkoxy sulfate or alkylarylpolyalkoxy sulfate having the following formula: RO(R'O).sub.n SO.sub.3 M wherein R is an alkyl group, linear or branched, having from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene and xylene having attached thereto at least one alkyl group, linear or branched, having from 9 to 15 carbon atoms; R' is ethylene or a mixture of ethylene and higher molecular weight alkylene with relatively more ethylene than higher alkylene; n is a number including fractional numbers, from 2 to 10; and M is a monovalent cation selected from the group consisting of sodium, potassium, lithium and ammonium; (c) injecting a third fluid containing from 0.1 to 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R.sub.a (OR.sub.a ').sub.na OH wherein R a is a branched or linear alkyl group, containing from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene or xylene having attached thereto at least one alkyl group, linear or branched, containing from 9 to 15 carbon atoms, R a ' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and na is a number either whole or fractional, from 1 to 10, said second fluid and third fluid mixing in the formation forming a macroemulsion in the more permeable strata of the formation, thereby reducing the permeability of the strata invaded by the emulsifying fluid; and (d) thereafter injecting a fourth fluid comprising an aqueous oil-displacing fluid into the formation; said fluid invading at least one stratum not invaded by the first oil displacing fluid of step (a) and displacing oil therein toward the production well when it is recovered to the surface of the earth.

Claim 18

A method of recovering petroleum from a subterranean, petroleum-containing formation, the temperature of said formation being not greater than 150° F., said formation containing water whose salinity is from 10,000 to 200,000 parts per million total dissolved solids, said formation containing at least two distinct petroleum-containing strata or layers, the permeability of at least one of said strata being at least 50 percent greater than the permeability of the other stratum, said formation being penetrated by at least one injection well and by at least one production well, both wells being in fluid communication with at least two of said formation strata, comprising (a) injecting a first fluid comprising an aqueous oil-displacing fluid into the formation via the injection well, said fluid passing through at least one of the more permeable strata of said formation and displacing oil therein toward the production well, from which it is recovered to the surface of the earth; (b) after said first aqueous oil displacing fluid has passed substantially through at least one of said more permeable strata to the production well, discontinuing injecting said first fluid and injecting into said stratum a second aqueous fluid containing from 0.01 to 10.0 percent by weight of an alkylpolyalkoxy sulfate or alkylarylpolyalkoxy sulfate having the following formula: RO(R'O).sub.n SO.sub.3 M wherein R is an alkyl group, linear or branched, having from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene and xylene having attached thereto at least one alkyl group, linear or branched, having from 9 to 15 carbon atoms; R' is ethylene or a mixture of ethylene and higher molecular weight alkylene with relatively more ethylene than higher alkylene; n is a number including fractional numbers, from 2 to 10; and M is a monovalent cation selected from the group consisting of sodium, potassium, lithium and ammonium; (c) injecting a third fluid containing from 0.1 to 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R.sub.a (OR.sub.a ').sub.na OH wherein R a is a branched or linear alkyl group, containing from 9 to 25 carbon atoms, or an alkylaryl group selected from the group consisting of benzene, toluene or xylene having attached thereto at least one alkyl group, linear or branched, containing from 9 to 15 carbon atoms, R a ' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and na is a number either whole or fractional, from 1 to 10, said second fluid and third fluid mixing in the formation forming a macroemulsion in the more permeable strata of the formation, thereby reducing the permeability of the strata invaded by the emulsifying fluid; and (d) thereafter injecting a fourth fluid comprising an aqueous oil-displacing fluid into the formation; said fluid invading at least one stratum not invaded by the first oil displacing fluid of step (a) and displacing oil therein toward the production well when it is recovered to the surface of the earth.