Concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature

Claim 2

A concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature, wherein said concentrate comprises: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR6## wherein the R and R 1 radicals are saturated or unsaturated hydrocarbon radicals having from 4 to 22 carbon atoms and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR7## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%.

Claim 3

A concentrate according to claim 1, wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group consisting of sodium, lithium, potassium and ammonium.

Claim 4

A concentrate according to claim 1, wherein said cosurfactant is selected from the group consisting of the mono- or polyhydroxylated alcohols.

Claim 5

A concentrate according to claim 1, wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.

Claim 6

A concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature, wherein said concentrate comprises a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR8## wherein R 2 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR9## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%.

Claim 7

A concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature, wherein said concentrate comprises a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR8## wherein R 2 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR9## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%.

Claim 8

A concentrate according to claim 5 wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group consisting of sodium, lithium, potassium and ammonium.

Claim 9

A concentrate according to claim 5 wherein said cosurfactant is selected from the group consisting of mono or polyhydroxylated alcohols.

Claim 10

A concentrate according to claim 5, wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.

Claim 11

A concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature, wherein said concentrate comprises: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR10## wherein the radical R 3 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms, n is a whole number between 0 and 20 and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR11## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, wherein the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%.

Claim 12

A concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature, wherein said concentrate comprises: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR10## wherein the radical R 3 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms, n is a whole number between 0 and 20 and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR11## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, wherein the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%.

Claim 13

A concentrate according to claim 9 wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group consisting of sodium, lithium, potassium and ammonium.

Claim 14

A concentrate according to claim 9 wherein said cosurfactant is selected from the group consisting of mono or polyhydroxylated alcohols.

Claim 15

A concentrate according to claim 9 wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.

Claim 16

A concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature, wherein said concentrate comprises: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and at least a salt of a derivative of a carboxylic acid selected from the group consisting of disodium nonylphenoxypolyethoxysulphosuccinate, disodium dodecanoxy polyethoxysulphosuccinate, each having between 0 and 20 ethoxy groups, tetrasodium N(1,2 dicarboxyethyl)-N-octadecylsulphosuccinamate, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%.

Claim 17

A concentrate for the preparation of oil and water microemulsions having high salinity which are stable at high temperature, wherein said concentrate comprises: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and at least a salt of a derivative of a carboxylic acid selected from the group consisting of disodium nonylphenoxypolyethoxysulphosuccinate, disodium dodecanoxy polyethoxysulphosuccinate, each having between 0 and 20 ethoxy groups, tetrasodium N(1,2 dicarboxyethyl)-N-octadecylsulphosuccinamate, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%.

Claim 18

A concentrate according to claim 13, wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group consisting of sodium, lithium, potassium and ammonium.

Claim 19

A concentrate according to claim 13, wherein said cosurfactant is selected from the group consisting of mono or polyhydroxylated alcohols.

Claim 20

A concentrate according to claim 13, wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.

Claim 21

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR12## wherein the R and R 1 radicals are saturated or unsaturated hydrocarbon radicals having from 4 to 22 carbon atoms and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR13## wherein the R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%, (b) X % of crude petroleum or of at least one petroleum cut; (c) Y % of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 22

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR12## wherein the R and R 1 radicals are saturated or unsaturated hydrocarbon radicals having from 4 to 22 carbon atoms and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR13## wherein the R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%, (b) X % of crude petroleum or of at least one petroleum cut; (c) Y % of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 23

A microemulsion according to claim 17, wherein said microemulsion contains 25% of said concentrate, 50% of oil and 25% of water.

Claim 24

A microemulsion according to claim 17, wherein said microemulsion contains crude petroleum and water having physical and chemical characteristics which are substantially identical with those of the deposit.

Claim 25

A microemulsion according to claim 17, wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group consisting of sodium, lithium, potassium and ammonium.

Claim 26

A microemulsion according to claim 17, wherein said cosurfactant is selected from the group consisting of the mono- or polyhydroxylated alcohols.

Claim 27

A microemulsion according to claim 17, wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.

Claim 28

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR14## wherein R 2 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR15## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or surfactants in said surfactants mixture being within the range of 5 to 50%, (b) X % of crude petroleum or of at least one petroleum cut; (c) Y % of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 29

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR14## wherein R 2 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR15## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or surfactants in said surfactants mixture being within the range of 5 to 50%, (b) X % of crude petroleum or of at least one petroleum cut; (c) Y % of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 30

A microemulsion according to claim 23, wherein said microemulsion contains 25% of said concentrate, 50% of oil and 25% of water.

Claim 31

A microemulsion according to claim 23, wherein said microemulsion contains crude petroleum and water having physical and chemical characteristics which are substantially identical with those of the deposit.

Claim 32

A microemulsion according to claim 23, wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group comprising sodium, lithium, potassium and ammonium.

Claim 33

A microemulsion according to claim 23, wherein said cosurfactant is selected from the group comprising the mono or polyhydroxylated alcohols.

Claim 34

A microemulsion according to claim 23, wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.

Claim 35

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR16## wherein the radical R 3 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms n is a whole number between 0 and 20 and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR17## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%, (b) X% of crude petroleum or of at least one petroleum cut; (c) Y% of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 36

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and a salt of a derivative of a carboxylic acid selected from the group consisting of a sulphosuccinic acid derivative corresponding to the general formula: ##STR16## wherein the radical R 3 is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms n is a whole number between 0 and 20 and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, and of a sulphosuccinamic acid derivative corresponding to the general formula: ##STR17## wherein R 4 and R 5 are each an H radical or a hydrocarbon radical which is saturated or unsaturated, and has from 4 to 22 carbon atoms, R 4 and R 5 being different when R 4 or R 5 is an H radical, and X + is selected from the group consisting of lithium, sodium, potassium and ammonium ions, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%, (b) X% of crude petroleum or of at least one petroleum cut; (c) Y% of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 37

A microemulsion according to claim 29 wherein said microemulsion contains 25% of said concentrate, 50% of oil and 25% of water.

Claim 38

A microemulsion according to claim 29, wherein said microemulsion contains crude petroleum and water having physical and chemical characteristics which are substantially identical with those of the deposit.

Claim 39

A microemulsion according to claim 29, wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group consisting of sodium, lithium, potassium and ammonium.

Claim 40

A microemulsion according to claim 29, wherein said cosurfactant is selected from the group consisting of mono or polyhydroxylated alcohols.

Claim 41

A microemulsion according to claim 29, wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.

Claim 42

A microemulsion according to claim 29, wherein said microemulsion comprises: (a) 25% of a concentrate containing: a salt of an alkylsulphuric acid in which the alkyl radical has from 6 to 22 carbon atoms, an alkylsulphosuccinate corresponding to the formula: ##STR18## where the R radical is a saturated or unsaturated hydrocarbon radical having from 4 to 22 carbon atoms, n is a whole number between 0 and 20 and X.sup.⊕ is selected from the group consisting of lithium, sodium, potassium and ammonium ions, alkylaryl sulphonates having a mean molecular weight within the range of 300 to 600 and a monohydroxylated alcohol; (b) 50% of crude petroleum or of a petroleum cut: (c) 25% of water having a monovalent ion salinity within the range of 50 to 60 g/l and a divalent ion salinity within the range of 5 to 10 g/l.

Claim 43

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and at least a salt of a derivative of a carboxylic acid selected from the group consisting of disodium nonylphenoxypolyethoxysulphosuccinate, disodium dodecanoxypolyethoxy sulphosuccinate, each having between 0 and 20 ethoxy groups, and tetrasodium N(1,2 dicarboxyethyl)-N-octadecylsulphosuccinamate, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%; (b) X% of crude petroleum or of at least one petroleum cut; (c) Y% of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 44

A microemulsion for assisted petroleum recovery from a deposit in which the water has high salinity, wherein said microemulsion contains by weight: (a) 10 to 30% of a concentrate comprising: a mixture of at least three surfactants constituted respectively by a salt of an alkylsulphuric acid wherein the alkyl radical has from 6 to 22 carbon atoms, a salt of an alkylaryl sulphonic acid having a mean molecular weight within the range of 300 to 600, and at least a salt of a derivative of a carboxylic acid selected from the group consisting of disodium nonylphenoxypolyethoxysulphosuccinate, disodium dodecanoxypolyethoxy sulphosuccinate, each having between 0 and 20 ethoxy groups, and tetrasodium N(1,2 dicarboxyethyl)-N-octadecylsulphosuccinamate, the weight percentage of each surfactant aforesaid in said mixture being within the range of 10 to 80%; and at least one cosurfactant constituted by a compound which is capable of forming hydrogen bonds with water, the weight percentage of the cosurfactant or cosurfactants in said surfactants mixture being within the range of 5 to 50%; (b) X% of crude petroleum or of at least one petroleum cut; (c) Y% of water having a monovalent ion salinity within the range of 30 to 80 g/l and a divalent ion salinity within the range of 0 to 15 g/l, X being approximately equal to 2Y.

Claim 45

A microemulsion according to claim 36, wherein said microemulsion comprises: 25% of a concentrate containing lauryl sodium sulphate, disodium nonylphenoxypolyethoxysulphosuccinate having between 0 and 20 ethoxy groups, alkylaryl sulphonates and isopropanol; 50% of crude petroleum or of a petroleum cut; 25% of water having a monovalent ion salinity of about 57 g/l and a divalent ion salinity of about 9.7 g/l.

Claim 46

A microemulsion according to claim 36, wherein said microemulsion contains 25% of said concentrate, 50% of oil and 25% of water.

Claim 47

A microemulsion according to claim 36, wherein said microemulsion contains crude petroleum and water having physical and chemical characteristics which are substantially identical with those of the deposit.

Claim 48

A microemulsion according to claim 36, wherein the salts of an alkylsulphuric acid and of an alkylaryl sulphonic acid are salts of a metal selected from the group consisting of sodium, lithium, potassium and ammonium.

Claim 49

A microemulsion according to claim 36 wherein said cosurfactant is selected from the group consisting of mono or polyhydroxylated alcohols.

Claim 50

A microemulsion according to claim 36, wherein the weight percentage of each surfactant aforesaid in said mixture is within the range of 10 to 60%.