Process for producing mineral oil using surfactants based on a mixture of C24 guerbet-, C26 guerbet-, C28-guerbet containing hydrocarbyl alkoxylates
The present invention relates to a surfactant mixture comprising at least three ionic surfactants which differ in terms of the hydrocarbyl moiety (R 1 )(R 2 )—CH—CH 2 — and are of the general formula (I) where R 1 , R 2 , A 0 , k, X, o, Y, a, b, M are each as defined in the description and the claims. The invention further relates to the use and preparation thereof, and to aqueous surfactant formulations comprising the mixtures, and to processes for producing mineral oil by means of Winsor type III microemulsion flooding, in which the aqueous surfactant formulation is injected into a mineral oil deposit through injection wells and crude oil is withdrawn from the deposit through production wells.
1. A process for producing mineral oil by means of Winsor type III microemulsion flooding, in which an aqueous surfactant formulation comprising a surfactant mixture comprising at least three ionic surfactants which differ in terms of the hydrocarbyl moiety (R 1 )(R 2 )—CH—CH 2 — and are of the general formula (I)
where
R 1 is a linear saturated or unsaturated aliphatic hydrocarbyl radical having 10 to 12 carbon atoms;
R 2 is a linear saturated or unsaturated aliphatic hydrocarbyl radical having 12 to 14 carbon atoms;
where the R 1 and R 2 radicals are selected such that the at least 3 ionic surfactants of the general formula (I) give rise to hydrocarbyl radicals (R 1 )(R 2 )CHCH 2 — with 24 carbon atoms, 26 carbon atoms, and 28 carbon atoms, wherein the C 24 surfactant of the general formula (I) is present within a range of from 40% to 60%, the C 26 surfactant of the general formula (I) within a range of from 30% to 50% and the C 28 surfactant of the general formula (I) within a range of from 7% to 20% based on the molar sum formed from the three surfactants;
each A 0 is independently ethylene, propylene or butylene;
k is an integer from 1 to 99,
X is a branched or unbranched hydrocarbylene group which has 1 to 10 carbon atoms and may be substituted by an OH group;
o is0 or 1;
M b+ is a cation;
Y a− is a sulfate group, sulfonate group, carboxylate group or phosphate group;
b is 1, 2 or 3 and
a is 1 or 2,
said surfactant formulation having a total surfactant content of 0.05 to 5% by weight based on the total amount of the aqueous surfactant formulation
is injected into a mineral oil deposit through at least one injection well for the purpose of lowering the interfacial tension between oil and water to <0.1 mN/m, and crude oil is withdrawn from the deposit through at least one production well.
2. The process according to claim 1 , wherein
R 1 is a linear saturated or unsaturated aliphatic hydrocarbyl radical having 10 or 12 carbon atoms; and
R 2 is a linear saturated or unsaturated aliphatic hydrocarbyl radical having 12 or 14 carbon atoms.
3. The process according to claim 1 , wherein k is an integer in the range from 4 to 50.
4. The process according to claim 1 , wherein the (—O—X—) o —Y a− radical in formula (I) is OS(O) 2 O − , OCH 2 CH 2 S(O) 2 O − , OCH 2 CH(OH)CH 2 S(O) 2 O − , O(CH 2 ) 3 S(O) 2 O − , S(O) 2 O − , CH 2 C(O)O − or CH 2 CH(R′)C(O)O − , where R′ is hydrogen or an alkyl radical having 1 to 4 carbon atoms.
5. The process according to claim 1 , wherein (—O-A 0 -) k in formula (I) represents n butyleneoxy, m propyleneoxy and 1 ethyleneoxy groups, where n+m+l=k.
6. The process according to claim 5 , wherein the n butyleneoxy, m propyleneoxy and l ethyleneoxy groups are arranged in blocks.
7. The process according to claim 6 , wherein the (R 1 )(R 2 )—CH—CH 2 — radical in formula (I) is followed, representing (—O-A 0 -) k , by a butyleneoxy block with n butyleneoxy groups, followed by a propyleneoxy block with m propyleneoxy groups, and finally an ethyleneoxy block with l ethyleneoxy groups.
8. The process according to claim 5 , wherein m is an integer from 4 to 15 and/or l is an integer of 0 to 25 and/or n is an integer from 2 to 15.
9. The process according to claim 1 , wherein the surfactant mixture further comprises surfactants of the formula
and of the formula
where R 1 , R 2 , A 0 , X, Y a− , M b+ , k, o, a and b are each as defined for formula (I).
10. The process according to claim 9 , wherein the proportion of surfactants of the formula (I) in relation to the sum of the amounts of surfactants of the formulae (I), (II) and (III) is in the range from 80% by weight to 99% by weight.
11. The process according to claim 1 , wherein said aqueous surfactant formulation has a total surfactant content of 0.05 to 5% by weight based on the total amount of the aqueous surfactant formulation.
12. A method comprising injecting a surfactant mixture comprising at least three ionic surfactants which differ in terms of the hydrocarbyl moiety (R 1 )(R 2 )—CH—CH 2 — and are of the general formula (I)
where
R 1 is a linear saturated or unsaturated aliphatic hydrocarbyl radical having 10 to 12 carbon atoms;
R 2 is a linear saturated or unsaturated aliphatic hydrocarbyl radical having 12 to 14 carbon atoms;
where the R 1 and R 2 radicals are selected such that the at least 3 ionic surfactants of the general formula (I) give rise to hydrocarbyl radicals (R 1 )(R 2 )CHCH 2 — with 24 carbon atoms, 26 carbon atoms, and 28 carbon atoms, wherein the C 24 surfactant of the general formula (I) is present within a range of from 40% to 60%, the C 26 surfactant of the general formula (I) within a range of from 30% to 50% and the C 28 surfactant of the general formula (I) within a range of from 7% to 20% based on the molar sum formed from the three surfactants;
each A 0 is independently ethylene, propylene or butylene;
k is an integer from 1 to 99,
X is a branched or unbranched hydrocarbylene group which has 1 to 10 carbon atoms and may be substituted by an OH group;
o is 0 or 1;
M b+ is a cation;
Y a− is a sulfate group, sulfonate group, carboxylate group or phosphate group;
b is 1, 2 or 3 and
a is 1 or 2,
in a mineral oil deposit in mineral oil production by means of Winsor type III microemulsion flooding.