High conformance oil recovery process

Claim 1

A method of recovering petroleum from a subterranean, petroleum-containing formation, 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 substantially all of said formation, 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 through at least one of said more permeable strata to the production well, discontinuing injecting said fluid and injecting into said stratum an aqueous fluid containing an emulsifying surfactant mixture comprising (1) from 0.01 to 10.0 percent by weight of an alkylpolyalkoxyalkylene sulfonate or alkylarylpolyalkoxyalkylene sulfonate having the following formula: R--(OR').sub.n --R"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 molecular weight alkylene; n is a number including fractional numbers, from 2 to 10; R" is ethylene, propylene, hydroxy propylene, or butylene 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 water insoluble nonionic surfactant having the following formula: R'''(OR'''').sub.n OH wherein R''' is a branched or linear alkyl group having 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, containing from 9 to 15 carbon atoms, R'''' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and n is a number from 2 to 10, said emulsifying surfactants forming a macro-emulsion in the flow channels of the most 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 oil displacing fluid invading at least one stratum not invaded by the oil displacing fluid of step (a) above, displacing petroleum 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, 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 substantially all of said formation, 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 through at least one of said more permeable strata to the production well, discontinuing injecting said fluid and injecting into said stratum an aqueous fluid containing an emulsifying surfactant mixture comprising (1) from 0.01 to 10.0 percent by weight of an alkylpolyalkoxyalkylene sulfonate or alkylarylpolyalkoxyalkylene sulfonate having the following formula: R--(OR').sub.n --R"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 molecular weight alkylene; n is a number including fractional numbers, from 2 to 10; R" is ethylene, propylene, hydroxy propylene, or butylene 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 water insoluble nonionic surfactant having the following formula: R'''(OR'''').sub.n OH wherein R''' is a branched or linear alkyl group having 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, containing from 9 to 15 carbon atoms, R'''' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and n is a number from 2 to 10, said emulsifying surfactants forming a macro-emulsion in the flow channels of the most 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 oil displacing fluid invading at least one stratum not invaded by the oil displacing fluid of step (a) above, displacing petroleum therein toward the production well where it is recovered to the surface of the earth.