High conformance oil recovery process

Claim 1

A method of recovering petroleum from a subterranean, petroleum-containing formation, said formation containing water whose salinity is from 0 to 20,000 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 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 stratum to the production well, discontinuing injecting said fluid and injecting into said stratum an aqueous emulsifying fluid containing a mixture of at least two surfactants comprising (1) an organic sulfonate selected from the group consisting of linear or branched alkyl sulfonates containing from 8 to 20 carbon atoms, alkylarylsulfonates having at least one alkyl group containing from 9 to 18 carbon atoms, and petroleum sulfonates which are at least partially water soluble having a median equivalent weight from 350 to 450, and (2) from 0.1 to 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R(OR').sub.n OH wherein R is a branched or linear alkyl group, containing from 7 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 5 carbon atoms, R' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and n is a number either whole or fractional, from 1 to 10, said emulsifying surfactant mixture 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 water whose salinity is from 0 to 20,000 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 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 stratum to the production well, discontinuing injecting said fluid and injecting into said stratum an aqueous emulsifying fluid containing a mixture of at least two surfactants comprising (1) an organic sulfonate selected from the group consisting of linear or branched alkyl sulfonates containing from 8 to 20 carbon atoms, alkylarylsulfonates having at least one alkyl group containing from 9 to 18 carbon atoms, and petroleum sulfonates which are at least partially water soluble having a median equivalent weight from 350 to 450, and (2) from 0.1 to 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R(OR').sub.n OH wherein R is a branched or linear alkyl group, containing from 7 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 5 carbon atoms, R' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and n is a number either whole or fractional, from 1 to 10, said emulsifying surfactant mixture 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 16

A method of recovering petroleum from a subterranean, petroleum-containing formation, said formation containing water whose salinity is from 0 to 20,000 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 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 stratum to the production well, discontinuing injecting said fluid and injecting into said stratum a second aqueous fluid containing from 0.01 to 10.0 percent by weight of an organic sulfonate selected from the group consisting of linear or branched alkyl sulfonates containing from 8 to 20 carbon atoms, alkylarylsulfonates having at least one alkyl group containing from 9 to 18 carbon atoms, and petroleum sulfonates which are at least partially water soluble having a median equivalent weight from 350 to 450, (c) injecting a third aqueous fluid containing from 0.01 to 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R(OR').sub.n OH wherein R is a branched or linear alkyl group, containing from 7 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' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and n is a number either whole or fractional, from 1 to 10, said fluid of step (c) being injected sequentially with said fluid of step (b) so the fluids mix in the formation to form an emulsifying fluid which forms 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 (d) thereafter injecting a fourth aqueous fluid into the formation, said 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 17

A method of recovering petroleum from a subterranean, petroleum-containing formation, said formation containing water whose salinity is from 0 to 20,000 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 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 stratum to the production well, discontinuing injecting said fluid and injecting into said stratum a second aqueous fluid containing from 0.01 to 10.0 percent by weight of an organic sulfonate selected from the group consisting of linear or branched alkyl sulfonates containing from 8 to 20 carbon atoms, alkylarylsulfonates having at least one alkyl group containing from 9 to 18 carbon atoms, and petroleum sulfonates which are at least partially water soluble having a median equivalent weight from 350 to 450, (c) injecting a third aqueous fluid containing from 0.01 to 5.0 percent by weight of a low HLB, water insoluble nonionic surfactant having the following formula: R(OR').sub.n OH wherein R is a branched or linear alkyl group, containing from 7 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' is ethylene or a mixture of ethylene and propylene with relatively more ethylene than propylene; and n is a number either whole or fractional, from 1 to 10, said fluid of step (c) being injected sequentially with said fluid of step (b) so the fluids mix in the formation to form an emulsifying fluid which forms 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 (d) thereafter injecting a fourth aqueous fluid into the formation, said 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.