WO2014064152A1

WO2014064152A1 - Process for mineral oil production using surfactants at least comprising a secondary alkanesulphonate and an alkyl ether sulphate/sulphonate/carboxylate/phosphate

Info

Publication number: WO2014064152A1
Application number: PCT/EP2013/072171
Authority: WO
Inventors: Christian Bittner; Günter OETTER; Jack Tinsley; Christian Spindler; Gabriela ALVAREZ JÜRGENSON; Sophie Maitro-Vogel
Original assignee: Basf Se
Priority date: 2012-10-26
Filing date: 2013-10-23
Publication date: 2014-05-01
Also published as: AR093166A1

Abstract

The present invention relates to a surfactant mixture comprising at least one secondary alkanesulphonate having 14 to 17 carbon atoms, of the general formula (I), and at least one anionic surfactant of the general formula (II), where R¹, R², R³, R⁴, A⁰, k, X, o, Y, a, b and M possess the definition specified in the description and the claims. The invention further relates to the use and preparation thereof, and also to aqueous surfactant formulations comprising the surfactant mixture, and to processes for producing mineral oil by means of Winsor type III microemulsion flooding, in which the aqueous surfactant formulation is injected through injection wells into a mineral oil deposit, and crude oil is withdrawn through production wells from the deposit.

Description

PROCESS FOR OXYGENIZATION USING TENSIDES

AT LEAST CONTAINING A SECONDARY ALKANSULFONATE AS WELL AS AN ALKYL ETHERSULFATE / SULFONATE / CARBOXYLATE / PHOSPHATE

description

The present invention relates to a surfactant mixture, its use and preparation, and to aqueous surfactant formulations containing the surfactant mixture and processes for producing oil by means of Winsor Type III microemulsion flooding, in which the aqueous surfactant formulation is injected through injection wells into a crude oil deposit and crude oil is removed from the deposit through production wells.

In natural oil deposits, petroleum is present in the cavities of porous reservoirs, which are closed to the earth's surface of impermeable cover layers. The cavities may be very fine cavities, capillaries, pores or the like. Fine pore necks, for example, have a diameter of only about 1 μηη. In addition to crude oil, including natural gas, a deposit contains more or less saline water.

Oil production generally distinguishes between primary, secondary and tertiary production. In primary production, after drilling the deposit, petroleum automatically streams through the borehole due to the inherent pressure of the deposit.

After the primary funding, therefore, the secondary funding is used. In secondary production, additional wells will be drilled into the oil-bearing formation in addition to the wells that serve to extract the oil, known as production wells. Through these so-called injection wells water is injected into the reservoir to maintain or increase the pressure. By injecting the water, the oil is slowly forced through the cavities into the formation, starting from the injection well, in the direction of the production well. But this works only as long as the cavities are completely filled with oil and the viscous oil is pushed through the water in front of him. As soon as the low-viscosity water breaks through cavities, it flows from this point on the path of least resistance, ie through the channel formed, and no longer pushes the oil in front of it.

By means of primary and secondary production, as a rule only about 30-35% of the quantity of crude oil in the deposit can be extracted. It is known to further increase the oil yield by measures of tertiary oil production. An overview of tertiary oil production can be found, for example, in "Journal of Petroleum Science of Engineering 19 (1998)", pages 265 to 280. Tertiary oil production includes heat processes in which hot water or superheated steam is injected into the deposit, which reduces the viscosity of the oil ₂ or use nitrogen.

Tertiary oil production further includes processes in which suitable chemicals are used as auxiliaries for oil extraction. With these, the situation can be influenced towards the end of the flood and thus also promote oil that was previously held in the rock formation.

Viscous and capillary forces act on the oil trapped in the pores of the reservoir rock towards the end of the secondary production, and the ratio of these two forces to one another determines the microscopic oil removal. By means of a dimensionless parameter, the so-called capillary number, the influence of these forces is described. It is the ratio of the viscosity forces (velocity x viscosity of the pressing phase) to the capillary forces (interfacial tension between oil and water x wetting of the rock):

σ cos0

Where μ is the viscosity of the oil mobilizing fluid, v the Darcy velocity (flow per unit area), σ the interfacial tension between petroleum mobilizing liquid and petroleum, and Θ the contact angle between petroleum and rock (C. Melrose, CF Brandner, J.Canadian Petr. Techn. 58, Oct.-Dec., 1974). The higher the capillary number, the greater the mobilization of the oil and thus also the degree of de-oiling.

It is known that the capillary number ^{"is 6,} and that it is necessary for the capillary to about ^10" near the end of secondary oil recovery in the range of about 10 to increase ^{from 3} to 10 ^"2 to mobilize additional mineral oil.

For this one can carry out a special form of the flood procedure - the so-called Winsor type III microemulsion flooding. In Winsor Type III microemulsion flooding, the injected surfactants are expected to form a microemulsion Windsor Type III with the water and oil phases present in the reservoir. A microemulsion Windsor Type II I is not an emulsion with particularly small droplets, but a thermodynamically stable, liquid mixture of water, oil and surfactants. Your three advantages are that thereby achieving a very low interfacial tension σ between petroleum and aqueous phase,

it usually has a very low viscosity and is therefore not trapped in a porous matrix,

- It arises even at very low energy inputs and can remain stable over an infinitely long period of time (classical emulsions, however, require higher shear forces, which are mostly not in the reservoir, and are only kinetically stabilized). The microemulsion Winsor Type III is in equilibrium with excess water and excess oil. Under these conditions, the microemulsion formation, the surfactants demonstrate the oil-water interface and lower the interfacial tension σ values of <10 ^"2 mN / m (ultralow interfacial surfactant-sion) are particularly preferred in. In order to achieve an optimum result, the proportion should the Microemulsion in the system water-microemulsion oil with a defined amount of surfactant naturally be as large as possible, since thereby the lower interfacial tensions can be achieved.

In this way, the shape of the oil droplets can be changed (interfacial tension between oil and water is lowered so far that the state of the smallest boundary surface is no longer sought and the spherical shape is no longer preferred) and by the flood water through the capillary openings squeeze through.

If all oil-water interfaces are coated with surfactant, the Winsor Type III microemulsion will be formed if there is an excess amount of surfactant. It thus represents a reservoir for surfactants, which accomplish a very low interfacial tension between oil and water phase. By virtue of the low viscosity of the Winsor Type III microemulsion, it migrates through the porous reservoir rock during the flooding process (emulsions, however, can become trapped in the porous matrix and clog reservoirs). If the Winsor Type III microemulsion encounters an oil-water interface not yet covered with surfactant, the surfactant from the microemulsion can significantly lower the interfacial tension of this new interface and result in mobilization of the oil (for example by deformation of the oil droplets).

The oil droplets can then combine to form a continuous oil bank. This has two advantages:

On the one hand, as the continuous oil bank progresses through new porous rock, the oil droplets located there can merge with the bank. Furthermore, the oil-water interface is significantly reduced by the union of the oil drops to an oil bank and thus released no longer needed surfactant. The released surfactant may thereafter mobilize residual oil remaining in the formation as described above.

Consequently, Winsor Type III microemulsion flooding is an extremely efficient process and, unlike an emulsion flooding process, requires significantly less surfactant. In microemulsion flooding, the surfactants are usually optionally injected together with cosolvents and / or basic salts (optionally in the presence of chelating agents). Subsequently, a solution of thickening polymer is injected for mobility control. Another variant is the injection of a mixture of thickening polymer and surfactants, cosolvents and / or basic salts (optionally with chelating agent) and subsequently a solution of thickening polymer for mobility control. These solutions should usually be clear to avoid blockage of the reservoir.

The requirements for surfactants for tertiary mineral oil production differ significantly from requirements for surfactants for other applications: Suitable surfactants for tertiary oil production are the interfacial tension between water and oil (usually approx. 20 mN / m) to particularly low values of less than 10 ^{". 2} mN / m to allow sufficient mobilization of the petroleum at the usual deposit temperatures of about 15 ° C to 130 ° C and in the presence of high salty water, especially in the presence of high levels of calcium and or magnesium ions, the surfactants must therefore also be soluble in strongly salty deposit water.

In order to meet these requirements, mixtures of surfactants have frequently been proposed, in particular mixtures of anionic and nonionic surfactants.

No. 3,811,1507 describes the combination of linear alkyl sulfonates or alkylaryl sulfonates with alkyl ether sulfates, where the alkyl ether sulfate is an alkyl polyethylene oxysulfate.

GB 2,168,094 describes the combination of internal olefin sulfonates with alkyl ether sulfonates.

No. 7,119,125 B1 describes a mixture of sulfated Guerbet alcohol alkoxylate and low molecular weight sulfated alkyl alkoxylate in oil production. The bimodal distribution is assigned particularly good emulsifying properties. These Emulsifying properties, however, do not play a major role in microemulsion flooding according to Winsor type III. One would need too much surfactant for the emulsification of oil and the required shear forces are hardly in the flood process before (apart from the area around the injector).

US-A 2009/270281 describes the use of a surfactant mixture for crude oil production, which contains at least one surfactant having an alkyl radical of 12 to 30 carbon atoms and a branched cosurfactant having an alkyl radical of 6 to 1 1 carbon atoms. The degree of branching of the alkyl radical in the cosurfactant ranges from 1 to 2.5 and may thus include Guerbet alcohols of the type 2-ethylhexyl or 2-propylheptyl. The cosurfactants may be alcohol ethoxylates or anionic modified alcohol ethoxylates (for example, alkyl ether sulfate).

No. 201 1 / 247,830 A1 describes surfactant mixtures containing surfactants based on a branched C 17 H 35 -alkyl radical.

WO 201 1/1 10502 A1 describes surfactant mixtures containing surfactants based on a linear C16H33 and C18H37-alkyl radical. WO 201 1/1 10503 A1 describes surfactant mixtures containing anionically modified alkyl alkoxylates which contain butyleneoxy units.

Further surfactant mixtures are described in WO 201 1/037975 A2, WO 201/1 10501 A1, WO 201 1 130310, WO 201 1/131549 A1 and WO 201 1/131719 A1.

The parameters of use, such as the type, concentration and mixing ratio of the surfactants used, are adapted by the person skilled in the art to the conditions prevailing in a given oil formation (for example temperature and salinity).

As described above, the oil production is proportional to the capillary number. This is the higher the lower the interfacial tension between oil and water. Low interfacial tensions are the more difficult to achieve the higher the average number of carbon atoms in the crude oil. For low interfacial tensions, surfactants are suitable which have a long hydrophobicity. This hydrophobic group may be an alkyl group or an alkyl group extended with hydrophobic alkyleneoxy units. The longer the hydrophobicity is, the better the interfacial tensions can be reduced, but the solubility of the compound usually decreases. Therefore, a second surfactant is usually needed to improve the solubility or the interfacial tension. An object of the present invention is therefore to provide a particularly efficient surfactant mixture for use in surfactant flooding, as well as an improved process for tertiary mineral oil production.

The object is achieved by a surfactant mixture, wherein the surfactant mixture contains at least one secondary alkanesulfonate of the general formula (I)

ROS Mb Mb ⁺ (I)

FT O and at least one anionic surfactant of the general formula (II)

contains, where

R ¹ and R ² independently represent a linear or branched, saturated aliphatic hydrocarbon radical, wherein the radical R ¹ CHR ^{2 has} 14 to 17 carbon atoms;

R ^{3 is} a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical and

R ^{4 is} H or a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical, the radical R ³ R ⁴ CHCH ₂ having from 8 to 44 carbon atoms;

each A ° independently for ethylene, propylene or butylene;

k is an integer from 1 to 99,

X is a branched or unbranched alkylene group having 1 to 10 carbon atoms which may be substituted with an OH group;

o for 0 or 1;

each M ^{b +} independently for a cation with the charge b;

Y ^{a "represents} a sulfate group, sulfonate group, carboxylate group or a phosphate group;

b for 1, 2 or 3 and

a stands for 1 or 2. Another aspect of the present invention relates to an aqueous surfactant formulation comprising a surfactant mixture according to the invention, wherein preferably the aqueous surfactant formulation has a total surfactant content of 0.05 to 5 wt.% Relative to the total amount of the aqueous surfactant formulation.

A further aspect of the present invention relates to the use of a surfactant mixture according to the invention or an aqueous surfactant formulation according to the invention in the field of mineral oil production by means of Winsor Type III microemulsion flooding. Another aspect of the present invention relates to methods for oil production, by Winsor type III microemulsion flooding, wherein an aqueous surfactant formulation according to the invention containing a surfactant mixture to lower the interfacial tension between oil and water to <0.1 mN / m, by at least one injection well into a Erdöllagerstätte pressed and crude oil is removed from the deposit through at least one production well.

Accordingly, a mixture of at least one surfactant of the general formula (I) and at least one surfactant of the general formula (II) and a process for tertiary mineral oil production by means of Winsor Type III microemulsion flooding are provided, wherein an aqueous surfactant formulation comprising at least one surfactant of general formula (I) and at least one surfactant of the general formula (II) is injected into at least one injection well in a Erdöllagerstätte, the interfacial tension between oil and water to values <0.1 mN / m, preferably to values <0.05 mN / m, more preferably to values <0.01 mN / m is lowered, and the deposit is withdrawn through at least one production well crude oil.

In a preferred embodiment, the weight-based ratio of surfactant of the general formula (I) to surfactant of the general formula (II) is between 1:19 and 19: 1. More preferably, the ratio of (I) to (II) is between 1: 9 and 9: 1. Even more preferably, the ratio of (I) to (II) is between 1: 9 and 1: 1 .01.

In a preferred embodiment, in general formula (I), R ^{1 is} a linear saturated aliphatic hydrocarbon radical and R ^{2 is} a linear saturated aliphatic hydrocarbon radical, wherein the alkyl radical R ¹ CHR ^{2 is} a hydrocarbon radical having 14 to 17 carbon atoms. In formula (I), M ^{b +} is preferably Na ⁺ .

In a further preferred embodiment, a mixture of 4 surfactants of the general formula (I) with different numbers of carbon atoms is present. In a particularly preferred embodiment, based on the aforementioned mixture of 4 surfactants of the general formula (I) with different carbon atom number, the proportion of surfactants of the formula (I), in each case based on the radical R ¹ R ² CH- with 14 carbon atoms at 20-30 mol%, the proportion of surfactants of the formula (I) with 15 carbon atoms at 25-30 mol. %, the proportion of surfactants of the formula (I) with 16 carbon atoms at 20-30 mol .-% and the proportion of surfactants of the formula (I) with 17 carbon atoms at mol .-% 10-20%, in each case based on all radicals R ¹ R ² CH- of these 4 surfactants.

In a further preferred embodiment, in general formula (II) R ^{3 is} a linear, saturated or unsaturated aliphatic hydrocarbon radical having 14 to 16 carbon atoms and R ^{4 is} a hydrogen atom.

In a very preferred embodiment, in general formula (II) R ^{3 is} a linear, saturated aliphatic hydrocarbon radical having 14 or 16 carbon atoms and R ^{4 is} a hydrogen atom. It is further preferred that the proportion by weight of these 2 ionic surfactants of the formula (II), based on the total weight of the surfactant mixture according to the invention, is greater than 50% by weight, more preferably greater than 60% by weight, more preferably greater than 70% by weight. , more preferably greater than 80 wt .-%, more preferably greater than 90 wt .-% is. In a further preferred embodiment, in general formula (II) R ^{3 is} a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 10 or 12 carbon atoms and R ^{4 is} a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 12 or 14 carbon atoms ,

In a particularly preferred embodiment, in general formula (II) R ^{3 is} a linear, saturated or unsaturated (preferably saturated) aliphatic hydrocarbon radical having 10 or 12 carbon atoms and R ^{4 is} a linear, saturated or unsaturated (preferably saturated) aliphatic hydrocarbon radical 12 or 14 carbon atoms, and in particular by at least 3 ionic surfactants of the formula (II) having a hydrocarbon radical having 24 carbon atoms, 26 carbon atoms and 28 carbon atoms. If the molar sum of these three surfactants is formed, the C ₂ 4 surfactant of the formula (II) is particularly preferably-in each case based on the radical R ³ R ⁴ CHCH ₂ -in a range from 40 mol% to 60 mol .-%, the C ₂₆ surfactant of formula (II) in a range of 30 mol% to 50 mol .-% and the C ₂ 8 surfactant of formula (II) in a range of 1 mol .-% to 20 mol .-% based on the sum of the proportions of these surfactants before. It is further preferred that the proportion by weight of these 3 ionic surfactants based on the total weight of the surfactant mixture according to the invention greater than 50 wt .-%, more preferably greater than 60 wt .-%, more preferably greater than 70 wt .-%, more preferably greater than 80 wt .-%, more preferably greater than 90 wt .-% is. In a further preferred embodiment, in general formula (II) R ^{3 is} a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 14 or 16 carbon atoms and R ^{4 is} a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 16 or 18 carbon atoms ,

In a particularly preferred embodiment, in general formula (II) R ^{3 is} a linear, saturated or unsaturated (preferably saturated) aliphatic hydrocarbon radical having 14 or 16 carbon atoms and R ^{4 is} a linear, saturated or unsaturated (preferably saturated) aliphatic hydrocarbon radicals having 16 or 18 carbon atoms, and in particular characterized in that at least 3 ionic surfactants of the formula (II) having a hydrocarbon radical based on the radical R ³ R ⁴ CHCH ₂ having 32 carbon atoms, 34 carbon atoms and 36 carbon atoms. If the molar sum of these three surfactants is formed, the C ₃₂ surfactant of the formula (II) is particularly preferably in a range from 20% to 40%, and the C ₃ 4 surfactant of the formula (II) in a range of 41 % to 60% and the C ₃ 6 surfactant of formula (II) in a range of 10% to 35% based on the total. It is further preferred that the proportion by weight of these 3 ionic surfactants based on the total weight of the surfactant mixture according to the invention greater than 50 wt .-%, more preferably greater than 60 wt .-%, more preferably greater than 70 wt .-%, more preferably greater than 80 wt .-%, more preferably greater than 90 wt .-% is.

The alkyleneoxy (AO) groups OA ° in general formula (II), which occur k-fold, may be the same or different. If these are different, they may be distributed statistically, alternately or in blocks, i. be arranged in two, three, four or more blocks.

Accordingly, in general formula (II) (OA) _{k can be} n butyleneoxy (BuO), m propyleneoxy (PO) and I ethyleneoxy (EO) groups, where n, m, I are natural numbers including 0 and it holds: n + m + I = k.

Preferably, the n-butylene, m-propylene and ethyleneoxy groups are at least partially (preferably in numbers of at least 50 mol%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90%, in particular completely) arranged in blocks.

Arranged in blocks means in the context of the present invention that at least one AO has a neighboring group AO, which is chemically identical, so that these form at least two AO a block. Preferably, then following the radical (R ³ ) (R ⁴ ) -CH-CH ₂ - in formula (II) for _k (OA) _k a Butylenoxyblock with n Butylenoxygruppen, followed by a Propylenoxyblock with m propyleneoxy groups and finally an ethyleneoxy with I ethyleneoxy groups on.

In the general formula (II) defined above, k or the variables I, m and n stand for natural numbers including 0, ie for 0, 1, 2, etc. However, it is clear to one skilled in the polyalkoxylate art that they are in this definition is the definition of a single surfactant. In the case of the presence of surfactant mixtures or aqueous surfactant formulations which comprise several surfactants of the general formula (II), the numbers I, m and n are average values over all molecules of the surfactants, since in the alkoxylation of alcohol with ethylene - Lenoxid or propylene oxide or butylene oxide in each case a certain distribution of chain lengths is obtained. This distribution can be described in a manner known in principle by the so-called polydispersity D. D = M _w / M _n is the quotient of the weight average molecular weight and the number average molar mass. The polydispersity can be determined by means of the methods known to the person skilled in the art, for example by means of gel permeation chromatography.

Preferably, in general formula (II), k is an integer in the range of 4 to 50, more preferably in the range of 8 to 39.

The variable I represents a number from 0 to 99, preferably from 1 to 40, more preferably from 1 to 20; m is a number from 0 to 99, preferably from 1 to 20, particularly preferably from 4 to 15; n stands for a number from 0 to 99, preferably for 0 to 20, particularly prefers for 1 to 15, whereby furthermore the sum of the variables I, m, n gives a number from (in each case inclusive) 1 to 99. According to the invention, the sum I + m + n (= k) is a number which is in the range from 1 to 99, preferably in the range from 4 to 50, particularly preferably in the range from 8 to 39.

Preferably m is an integer from 4 to 15 (more preferably 5 to 9) and / or I is an integer from 0 to 25 (more preferably 4 to 15) and / or n is 0.

More preferably, m is an integer of 4 to 15 (more preferably 5 to 9) and / or I is an integer of 0 to 25 (more preferably 4 to 15) and / or n is an integer of 1 to 15 (more preferably 5 to 9). In general formula (II), X represents a branched or unbranched alkylene group having 1 to 10, preferably 2 to 4, carbon atoms which may be substituted with an OH group. The alkylene group is preferably a methylene, ethylene or propylene group. In particular, X is preferably CH ₂ CH ₂ , CH ₂ CH (OH) CH ₂ , (CH ₂ ) ₃ , CH ₂ or CH ₂ CH (R '), where R' is hydrogen or an alkyl radical having 1 to 4 carbon atoms (for example methyl ). X can be present (o = 1) or missing (o = 0).

In the above general formulas (I) and (II), M ^{+ is} independently a cation, preferably the cation is selected from the group consisting of Na ⁺ ; K ⁺ , Li ⁺ , NH ₄ ⁺ , H ⁺ , Mg ²⁺ and Ca ²⁺ (preferably Na ⁺ , K ⁺ or NH ₄ ⁺ ). Altogether b can stand for the values 1, 2 or 3. B is preferably 1 or 2, in particular 1. Each M ⁺ may be the same or different for formula (I); but prefers the same. Each M ⁺ may be the same or different for formula (II); but prefers the same. The cations M ⁺ may be the same or different in comparison with formula (I) and formula (II); but prefers the same.

In the general formula (II) above, Y ^{a "represents} a sulfonate, sulfate, carboxylate or phosphate group (preferably sulfonate, sulfate or carboxylate group, particularly preferably sulfate or carboxylate) Thus, a can be 1 or 2 stand.

Preferably, in general formula (II), the radical (OX) ₀ Y ^{a "is} OS (0) ₂ 0 ^" , OCH ₂ CH ₂ S (O) ₂ O ^" , OCH ₂ CH (OH) CH ₂ S (0) ₂ 0 ^" , 0 (CH ₂ ) ₃ S (0) ₂ 0 ^" , 0 (CH ₂ ) ₄ S (0) ₂ 0 ^" , S (0) ₂ 0 ^" , CH ₂ C (0) 0 ^" or CH ₂ CH (R ') C (O) O ^" , where R' is hydrogen or an alkyl radical having 1 to 4 carbon atoms (for example methyl).

According to a further preferred embodiment, the invention relates to a mixture of at least one surfactant of the general formula (I) and at least one surfactant of the general formula (II) and their use in oil production by means of Winsor type III microemulsion flooding, where I is an integer from 0 to 99, m is a number from 4 to 15 and n is a number from 0 to 15, and Y ^{a "is} selected from the group consisting of sulfate group, sulfonate group and carboxylate group, the groups BuO, PO and EO to more than 80% are in block form in the order BuO, PO, EO starting from (R ³ ) (R ⁴ ) -CH-CH ₂ and the sum I + m + n is in the range from 5 to 49.

A particularly preferred embodiment is when I is an integer from 0 to 99, m is a number from 5 to 9 and n is a number from 1 to 15, and Y ^{a "is} selected from the group consisting of sulfate group, Sulfonate group and carboxylate group, wherein the groups BuO, PO and EO are more than 80% in block form in the order BuO, PO and EO starting from (R ³ ) (R ⁴ ) -CH-CH ₂ , the Sum I + m + n is in the range of 4 to 50 and the block BuO consists of more than 80% of 1, 2-butylene oxide.

A preferred surfactant mixture according to the invention additionally contains, in addition to at least one surfactant of the general formula (I) and at least one surfactant of the general formula (II), at least one surfactant of the general formula (III)

and at least one surfactant of the general formula (IV)

wherein R ³ , R ⁴ , A °, X, Y ^{a "} , M ^{b +} , k, o, a and b have the meaning given for the general formula (II) and preferred meanings.

Preferably, the proportion of surfactants of the general formula (II) in relation to the sum of the amounts of surfactants of the formulas (I), (II), (III) and (IV) in the range of 80 wt .-% to 99 wt. -%.

According to a further preferred embodiment of the invention in the general formula (III) R ^{3 is} a linear, saturated aliphatic hydrocarbon radical having 10 or 12 carbon atoms and in the general formula (IV) R ^{4 is} a linear, saturated aliphatic hydrocarbon radical having 12 or 14 carbon - atoms.

According to a further preferred embodiment of the invention in the general formula (III) R ^{3 is} a linear, saturated aliphatic hydrocarbon radical having 14 or 16 carbon atoms and in the general formula (IV) R ^{4 is} a linear, saturated aliphatic hydrocarbon radical having 16 or 18 carbon atoms ,

As a result of the preparation, more than one surfactant of the general formula (II) may also be present in the surfactant mixture. The relative to the hydrocarbon moiety (R ³ ) (R ⁴ ) -CH-CH ₂ - different surfactants can be subsumed under the general formula (II). The difference may be due to the number of carbon atoms, the number the unsaturated bonds, the branching frequency and / or the degree of branching. In particular, the surfactants differ in chain length given for R ³ and R ⁴ . The alkyl radical R ³ R ⁴ CHCH ₂ is a hydrocarbon radical having 8 to 44 carbon atoms. These may be linear or branched, saturated or unsaturated aliphatic hydrocarbon radicals of the type R ³ R ⁴ CHCH ₂ . Optionally, R ⁴ can also be a hydrogen atom. In the case of branched hydrocarbon radicals of the type R ³ R ⁴ CHCH ₂ , branching degrees of 0.1 to 5 are preferred. More preferred are degrees of branching from 0.1 to 3.5 (more preferably 0.1 to 2.5).

The term "degree of branching" is hereby defined in a manner known in principle as the number of methyl groups in a molecule of the alcohol minus 1. The mean degree of branching is the statistical average of the degrees of branching of all molecules in a sample.

In compounds which are obtainable by hydrogenation of fatty acid methyl esters by way of example, in a preferred embodiment R ^{3 is} a linear, saturated or unsaturated aliphatic hydrocarbon radical having 14 to 16 carbon atoms and R ^{4 is} a hydrogen atom. In a very preferred embodiment, R ^{3 is} a linear saturated aliphatic hydrocarbon radical having 14 or 16 carbon atoms and R ^{4 is} a hydrogen atom.

Exemplary accessible by dimerization of alcohols compounds lead to R ³ / R ⁴ hydrocarbon chains with 10/12, 10/13, 10/14, 1 1/12, 1 1/13, 1 1/14, 12/12, 12 / 13, 12/14, preferably 10/12, 10/14, 12/12, 12/14 carbon atoms. There may also be more than three different surfactants of the general formula (II) in the surfactant mixture, as a result of the preparation. Preferably, the three surfactants with respect to the hydrocarbon moiety (R ³ ) (R ⁴ ) -CH-CH ₂ - 24, 26 and 28 carbon atoms, the main components of the surfactant mixture according to the invention. Their proportion is preferably at least 25 wt .-% based on the total weight of the surfactant mixture, more preferably at least 30 wt .-%, more preferably at least 40 wt .-%, more preferably at least 50 wt .-% , The radical R ³ is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 10 to 12 carbon atoms. The radical R ⁴ is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 12 to 14 carbon atoms. R ³ is either identical to R ⁴ or preferably has at most two C atoms (more preferably exactly two C atoms) less than R ⁴ . In the case of branched radicals R ^3, R ⁴ , the degree of branching in R ³ or R ^{4 is} preferably in the range from 0.1 to 5 (preferably from 0.1 to 1.5). For the branched aliphatic hydrocarbon radical (R ³ ) (R ⁴ ) -CHCH _2, this results in a degree of branching of 1.2 to 11 (preferably 1.2 to 4). However, a further preferred embodiment is the use of linear saturated or unsaturated radicals R ³ having 10 or 12 carbon atoms or R ⁴ having 12 or 14 carbon atoms. Particularly preferred is the use of linear saturated radicals R ³ and R ⁴ . This results in a degree of branching of 1 for the aliphatic hydrocarbon radical (R ³ ) (R ⁴ ) -CHCH ₂ .

Exemplary compounds obtainable by dimerization of alcohols lead to R ³ / R ⁴ alkyl chains having 14/16, 14/17, 14/18, 15/16, 15/17, 15/18, 16/16, 16/17, 16 / 18 - especially 14/16, 14/18, 16/16, 16/18 carbon atoms. Depending on the preparation, more than three different surfactants of the general formula (II) may also be present in the surfactant mixture. Preferably, the three surfactants form the major components of the surfactant mixture. Their proportion is preferably at least 25 wt .-% based on the total weight of the surfactant mixture, more preferably at least 30 wt .-%, more preferably at least 40 wt .-%, more preferably at least 50 wt .-%. The radical R ³ is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 14 to 16 carbon atoms. The radical R ⁴ is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 16 to 18 carbon atoms. R ³ is either identical to R ⁴ or has at most two C atoms (more preferably exactly two C atoms) less than R ⁴ . In the case of branched radicals R ³ or R ⁴ , the degree of branching at R ³ or R ^{4 is} preferably in the range from 0.1-5 (preferably from 0.1-1.5). For the branched aliphatic hydrocarbon radical (R ³ ) (R ⁴ ) -CHCH _2, this results in a degree of branching of 1, 2 to 1 1 (preferably 1, 2 to 4). However, a further preferred embodiment is the use of linear saturated or unsaturated radicals R ³ having 14 or 16 carbon atoms or R ⁴ having 14 or 16 carbon atoms. Particularly preferred is the use of linear saturated radicals R ³ and R ⁴ . This results in a degree of branching of 1 for the aliphatic hydrocarbon radical (R ³ ) (R ⁴ ) -CHCH ₂ . The alcohols (R ³ ) (R ⁴ ) -CH-CH ₂ -OH, which can serve as starting compound for the preparation of the surfactants of the invention are, for example, by hydrogenation of fatty acid methyl esters (R ⁴ is a hydrogen atom), Oxoalkoholsynthese or dimerization of alcohols of the type R ³ CH ₂ CH ₂ OH and R ⁴ OH (R ⁴ is not a hydrogen atom) accessible with elimination of water. Accordingly, a further aspect of the present invention is a process for preparing a surfactant mixture according to the invention comprising the steps:

For surfactants of the general formula (I)

(a) Preparation of a secondary alkanesulfonate of the general formula (I) wherein R ¹ and R ^{2 have} the abovementioned meaning, by sulfoxidation of an alkane mixture and subsequent reaction with alkali. Alternatively, a sulfochlorination of alkanes with subsequent reaction with caustic can be carried out.

The preparation of the surfactant of the general formula (I) in process step (a) is known to the person skilled in the art. In the usually preferred process of sulfoxidation, an alkane mixture is mixed with water and irradiated at 20-40 ° C with UV light (eg 10 - 40 kW mercury vapor lamps), wherein a mixture of sulfur dioxide and oxygen (molar ratio preferably 2: 1) is passed. In order to avoid the formation of multiple sulfonated compounds, the conversion is preferably limited to <5% (preferably <1%) and the target compounds are discharged. Unreacted alkane is returned to the process. The process is preferably continuous. The separation of the alkanesulfonic acids obtained from the residual alkane is carried out by phase separation. After removal of gases (S0 ₂ , S0 ₃ ), the alkanesulfonic acid is reacted with lye - preferably sodium hydroxide solution - to the surfactant.

For surfactants of the general formula (II)

(a ') Preparation of a fatty alcohol of the general formula (R ³ ) (R ⁴ ) -CH-CH ₂ OH (V), wherein R ³ and R ^{4 have} the abovementioned meaning - with the proviso that R ^{3 is} a linear saturated or unsaturated hydrocarbon radical and R ^{4 is} a hydrogen atom - have, by hydrolysis of a natural fat (triglyceride) using methanol and subsequent hydrogenation of the methyl ester to fatty alcohol. Alternatively, hydrolysis of the triglyceride to the fatty acid and subsequent hydrogenation to the fatty alcohol can take place. Another alternative is the preparation of the alcohols by the Ziegler method by oligomerization of ethylene on an aluminum catalyst and subsequent hydrolysis with water.

(b ') alkoxylation of the alcohols obtained in process step (a'),

(c ') Reaction of the alcohol alkoxylates obtained in step (b') with a group Y ^{a "} , if appropriate forming a spacer group OX The preparation of the fatty alcohol of the general formula (V) (R ³ ) (R ⁴ ) -CH-CH ₂ OH in process step (a ') is known to the person skilled in the art. This may include a C16C18 fatty alcohol mixture (linear, saturated), a C16C18 fatty alcohol mixture (linear and partially unsaturated) or a C16C18 mixture of Ziegler alcohols having 16 or 18 carbon atoms. For surfactants of the general formula (II)

(a ") Preparation of an oxoalcohol of the general formula (R ³ ) (R ⁴ ) -CH-CH ₂ OH (V), where R ³ and R ^{4 have} the abovementioned meaning, by reacting an olefin with carbon monoxide and hydrogen.

(b ") alkoxylation of the alcohols obtained in process step (a"),

(c ") Reaction of the alcohol alkoxylates obtained in step (b") with a group Y ^{a "} , if appropriate with formation of a spacer group OX.

The preparation of the oxoalcohol of the general formula (V) (R ³ ) (R ⁴ ) -CH-CH ₂ OH in process step (a ") is known to the person skilled in the art.

For surfactants of the general formula (II)

(a '") Preparation of Guerbet alcohols of the general formula (V) (R ³ ) (R ⁴ ) -CH-CH ₂ OH (V), where R ³ and R ^{4 have} the abovementioned meaning - with the proviso that R ⁴ is not a hydrogen atom and R ³ CH ₂ CH ₂ OH and R ⁴ OH have the same number of carbon atoms or differ in maximum by 2 carbon atoms - have, by condensation of a mixture of at least two primary alcohols of the formula R-CH ₂ -CH ₂ -OH, (b "') alkoxylation of the alcohols obtained in process step (a'"),

(c '") Reaction of the obtained in step (b'") alcohol alkoxylates with a group Y ^{a "} , optionally to form a spacer group OX.

The preparation of Guerbetalkohols the general formula (V) (R ³ ) (R ⁴ ) -CH-CH ₂ OH in process step (a '") is known in the art.

In the course of the Guerbet reaction, primary alcohols are ultimately dimerized in the presence of suitable catalysts to form β-branched primary alcohols. Aldehydes are formed primarily from the alcohol, which then undergo aldol condensation, with the elimination of water and subsequent hydrogenation to give saturated alcohols. In addition to the main product, the Guerbet alcohol, various by-products can also be formed, for example unsaturated β-branched primary alcohols if the hydrogenation of the double bond is not complete, saturated a-branched aldehydes, if the hydrogenation to Guerbet alcohol was not complete, or in particular β- branched primary alcohols having additional branching in the side chain or main chain. In the dimerization of the alcohols according to the formula R-CH 2 CH 2 -OH, it may be a mixture of alcohols. This may include a C12C14 fatty alcohol mixture (linear, saturated), a C12C14 mixture of Ziegler alcohols having 12 or 14 carbon atoms, a C12C14 fatty alcohol mixture (linear and partially unsaturated) or a mixture of C12C14-oxoalcohol.

Dimerization of the alcohols according to the formula R-CH 2 CH 2 -OH, wherein R is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 10 or 12 carbon atoms, provides Guerbet alcohols having 24, 26 and 28 carbon atoms according to a preferred embodiment of the invention ,

In a particularly preferred embodiment, R is a linear saturated or unsaturated (preferably saturated) aliphatic hydrocarbon radical having 10 or 12 carbon atoms.

To produce the Guerbet alcohols in process step (a '"), mixtures of the alcohols of the formula R-CH ₂ CH ₂ -OH are condensed, The proportion of alcohols having R = 10 carbon atoms is preferably between 60-80 mol%, and the proportion of alcohols R = 12 carbon atoms between 20-40 mol%, more preferably about 70 mol% of alcohols having R = 10 carbon atoms and 30 mol% of alcohols having R = 12 carbon atoms are reacted.

It can u.a. also a C16C18 fatty alcohol mixture (linear, saturated), a C16C18 mixture of Ziegler alcohols having 16 or 18 carbon atoms, a C16C18 fatty alcohol mixture (linear and partially unsaturated) or a mixture of C16C18 oxo alcohol.

Dimerization of the alcohols according to the formula R-CH ₂ CH ₂ -OH, wherein R is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical having 14 or 16 carbon atoms, provides Guerbet alcohols with 32, 34 according to a preferred embodiment of the invention and 36 carbon atoms.

In a particularly preferred embodiment, R is a linear saturated or unsaturated (preferably saturated) aliphatic hydrocarbon radical having 14 or 16 carbon atoms.

To produce the Guerbet alcohols in process step (a '"), mixtures of the alcohols of the formula R-CH ₂ CH ₂ -OH are condensed, The proportion of alcohols having R = 14 carbon atoms is preferably from 25 to 50 mol%, and the proportion of alcohols R = 16 carbon atoms between 50 to 75 mol% about 30 mol% of alcohols having R = 14 carbon atoms and 70 mol% of alcohols having R = 16 carbon atoms reacted.

The condensation of alcohols of the formula R-CH 2 CH 2 -OH to Guerbet alcohols is preferably carried out in the presence of from 0.5 to 10% by weight, based on the alcohol, alkali or alkaline earth hydroxide, for example lithium hydroxide, sodium hydroxide, cesium hydroxide or potassium hydroxide, preferably potassium hydroxide. In view of a high reaction rate and a small proportion of secondary components, the alkali metal or alkaline earth metal hydroxides in a concentration of 3 to 6 wt .-% based on the alcohol used. The alkali or alkaline earth metal hydroxide can be used in solid form (flakes, powder) or in the form of a 30 to 70%, preferably 50%, aqueous solution.

According to a preferred embodiment, the alcohols of the formula R-CH ₂ CH ₂ -OH are condensed in the presence of NaOH and / or KOH.

Suitable catalysts are the catalysts known from the prior art, for example nickel, lead salts (US Pat. No. 3,119,880), copper, lead, zinc, chromium, molybdenum, tungsten and magane oxides (US Pat. US 3,558,716), palladium complexes (US 3,979,466) or silver complexes (US 3,864,407). ZnO is preferably used as the catalyst for the dimerization. The catalyst or catalysts are preferably ZnO catalysts generally added to the mixture from which the Guerbet alcohols are made.

The mixture of Guerbet alcohols can be prepared by the process known from DE 3901095 A1.

According to a preferred embodiment of the invention, the Guerbet alcohols are in process step (a '") at a temperature in the range of 150 to 320 ° C, preferably at a temperature in the range of 180 to 280 ° C optionally in the presence of a catalyst or a plurality of catalysts synthesized.

The alcohols (R ³ ) (R ⁴ ) -CH-CH ₂ -OH obtained in process step (a), (a '") can be prepared in a manner known in principle by alkoxylation in process step (b \ b", b'"). ) are converted to alcohol alkoxylates. The implementation of such alkoxylations is known in principle to a person skilled in the art. It is also known to the person skilled in the art that the reaction conditions, in particular the choice of catalyst, can influence the molecular weight distribution of the alkoxylates.

The alcohol alkoxylates can be prepared in process step (b \ b ", b '") preferably by base-catalyzed alkoxylation. In this case, the alcohol (R ³ ) (R ⁴ ) -CH-CH ₂ - OH in a pressure reactor with alkali metal hydroxides, preferably potassium hydroxide, or with alkali alcoholates, such as sodium methylate, are added. By reduced pressure (for example <100 mbar) and / or increasing the temperature (30 to 150 ° C), water still present in the mixture can be removed. The alcohol is then present as the corresponding alkoxide. The mixture is then inertized with inert gas (for example nitrogen) and the alkylene oxide (s) is added stepwise at temperatures of 60 to 180 ° C up to a maximum pressure of 10 bar. According to a preferred embodiment, the alkylene oxide is initially metered in at 130.degree. In the course of the reaction, the temperature rises up to 170 ° C due to the released heat of reaction. According to a further preferred embodiment of the invention, the butylene oxide is first added at a temperature in the range of 125 to 145 ° C, then the propylene oxide is added at a temperature in the range of 130 to 145 ° C and then the ethylene oxide at a temperature in the range of 125 to 155 ° C was added. At the end of the reaction, the catalyst can be neutralized, for example by addition of acid (for example acetic acid or phosphoric acid) and filtered off as required.

However, the alkoxylation of the alcohols (R ³ ) (R ⁴ ) -CH-CH ₂ -OH can also be carried out by other methods, for example by acid-catalyzed alkoxylation. Furthermore, it is possible to use, for example, double hydroxide clays as described in DE 4325237 A1 or it is possible to use double metal cyanide catalysts (DMC catalysts). Suitable DMC catalysts are disclosed, for example, in DE 10243361 A1, in particular in sections [0029] to [0041] and the literature cited therein. For example, Zn-Co type catalysts can be used. To carry out the reaction, the catalyst can be added to the alcohol (R ³ ) (R ⁴ ) -CH-CH ₂ -OH, the mixture is dehydrated as described above and reacted with the alkylene oxides as described. It is usually not more than 1000 ppm catalyst used with respect to the mixture and the catalyst may remain in the product due to this small amount. The amount of catalyst can typically be less than 1,000 ppm, for example 250 ppm or less.

The process step (c \ c ", c '") relates to the reaction of the in step (b \ b ", b'") obtained alcohol alkoxylates having a group Y ^{a "} , optionally forming a spacer group OX.

Thus, for example, sulfate and phosphate groups can be introduced by reacting them directly (optionally after activation) with the alcohol alkoxylate. Sulfonate groups can be introduced by vinyl addition, substitution reaction or aldol reaction, if appropriate with subsequent hydrogenation, with corresponding spacer OX being produced. Alternatively, the alcohol alkoxylate may also be previously converted to a chloride, which is then subjected to a direct sulfonation reaction. phonation is accessible. Carboxylates can be obtained, for example, by reaction with chloroacetate, acrylate or substituted acrylates H ₂ C = (R ') C (O) O ^" , where R' is H or an alkyl radical having 1 to 4 carbon atoms (OX) ₀ Y ^{a "} from the functional group Y ^a" , which is a sulfate, sulfonate, carboxylate or phosphate group, and the spacer OX together, which in the simplest case (o = 0) may be a single bond In the case of a sulphonate group, for example, the reaction with propanesultone and subsequent neutralization, with butane sultone and subsequent neutralization, with vinylsulphonic acid sodium salt can be resorted to for example in the case of a sulphate group or with 3-chloro-2-hydroxypropanesulfonic acid sodium salt.For the preparation of sulfonates, the termin ale OH group in a chloride, for example, with phosgene or thionyl chloride and then reacted, for example, with sulfite. In the case of a carboxylate group, it is possible, for example, to resort to the oxidation of the alcohol with oxygen and subsequent neutralization or the reaction with sodium chloroacetate. Carboxylates can also be obtained, for example, by Michael addition of (meth) acrylic acid or esters. Phosphates can be obtained, for example, by esterification reaction with phosphoric acid or phosphorus pentachloride.

In addition to the surfactants according to the general formulas (I), (II), (III) and (IV), the surfactant mixture may furthermore optionally comprise further surfactants. Thus, for example, secondary alkanesulfonates having 12, 13 or 18 carbon atoms or primary alkanesulfonates having 12 to 18 carbon atoms may be present. Other surfactants may also be alkanedisulfonates. These may, for example, have 12 to 18 carbon atoms. However, anionic surfactants of the type alkylarylsulfonate or olefinsulfonate (alpha-olefinsulfonate or internal olefinsulfonate), alkyl ether sulfonate, alkyl ether carboxylate, alkyl ether sulfate and / or nonionic surfactants of the alkyl ethoxylate or alkyl polyglucoside type can also be used, for example. Betainic surfactants may also be used. These other surfactants may in particular also be oligomeric or polymeric surfactants. Such polymeric co-surfactants can advantageously reduce the amount of surfactants necessary to form a microemulsion. Thus, such polymeric cosurfactants are also referred to as "microemulsion boosters." Examples of such polymeric surfactants include amphiphilic block copolymers comprising at least one hydrophilic and at least one hydrophobic block, examples of which include polypropylene oxide-polyethylene oxide block copolymers, polyisobutene polyethylene oxide Block copolymers and comb polymers with polyethylene oxide side chains and a hydrophobic main chain, wherein the main chain preferably substantially olefins or (Meth) acrylates as structural units. As used herein, the term "polyethylene oxide" is intended to include polyethylene oxide blocks comprising propylene oxide units as defined above Further details of such surfactants are disclosed in WO 2006/131541 A1.

In the method according to the invention for producing crude oil, a suitable aqueous surfactant formulation of the surfactant mixture according to the invention is injected into the crude oil deposit through at least one injection well and crude oil is taken from the deposit through at least one production well. Of course, the term "crude oil" in this context does not mean phase-pure oil, but rather the customary crude oil-water emulsions, as a rule, a deposit is provided with several injection wells and several production wells By means of Winsor Type III microemulsion flooding, the surface tension between oil and water is reduced to values of <0.1 mN / m, preferably to <0.05 mN / m, particularly preferably to <0.01 mN / m, by using the aqueous surfactant formulation according to the invention Thus, the interfacial tension between oil and water will be in the range of 0.1 mN / m to 0.0001 mN / m, preferably values in the range of 0.05 mN / m to 0.0001 mN / m , particularly preferably lowered to values in the range of 0.01 mN / m to 0.0001 mN / m.

The main effect of the surfactant mixture according to the invention lies in the reduction of the interfacial tension between water and oil - desirably to values clearly <0.1 mN / m. Following the pressing in of the aqueous surfactant formulation, the so-called "surfactant flooding" or preferably the Winsor type III "microemulsion flooding", water can be injected into the formation to maintain the pressure ("water flooding") or, preferably, a higher viscous aqueous solution of a strong thickening polymer ("polymer flooding"). However, there are also known techniques by which the surfactants are first allowed to act on the formation. Another known technique is the injection of a solution of surfactants and thickening polymers followed by a solution of thickening polymer. The person skilled in the art knows details of the technical implementation of "surfactant flooding", "flooding" and "polymer flooding" and applies a corresponding technique depending on the nature of the deposit.

For the process according to the invention, an aqueous surfactant formulation which contains at least surfactants of the general formula (I) and formula (II) is used. The aqueous surfactant formulation may comprise further components besides the surfactant mixture. In addition to water, the formulations may optionally also contain water-miscible or at least water-dispersible organic or other agents as co-solvent. Such additives are used in particular for stabilizing the surfactant solution during storage or transport to the oil field. However, the amount of such cosolvents should as a rule not exceed 50% by weight, preferably 20% by weight, based on the total weight of the aqueous surfactant formulation. Examples of such cosolvents include, in particular, alcohols such as methanol, ethanol and n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, isopentanol, butylmonoethylene glycol, butyldiethylene glycol or butyltriethylene glycol. In a particularly advantageous embodiment of the invention, only water is used for formulation.

In a preferred embodiment of the invention, the surfactants of general formula (II) in the aqueous formulation, which is ultimately injected into the deposit, are said to constitute the major component among all surfactants. These are preferably at least 25% by weight, more preferably at least 30% by weight, very preferably at least 40% by weight and very, very preferably at least 50% by weight, based on the total weight of all surfactants used. The aqueous surfactant formulation according to the invention can preferably be used for the surfactant flooding of deposits. It is particularly suitable for Winsor type III microemulsion flooding (flooding in the Winsor III area or in the area of existence of the bicontinuous microemulsion phase). The technique of microemulsion flooding has already been described in detail at the beginning.

In addition to the surfactant mixture, the aqueous surfactant formulation may also contain other components, such as, for example, C ₄ -C ₈ -alcohols and / or basic salts (so-called "alkaline surfactant flooding") .These additions may be used, for example, to reduce the retention in the formation. The quantitative ratio of the alcohols with respect to the total amount of surfactant used is generally at least 1: 1 - however, a significant excess of alcohol can also be used Suitable basic salts are sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide or silicates basic salts is typically from 0.1% to 5% by weight, based on the total amount of the aqueous surfactant formulation. At least one chelating agent can be added to the basic salts.

The deposits in which the process is used, as a rule, have a temperature of at least 10 ° C, for example 10 to 150 ° C, preferably a temperature of at least 15 ° C to 120 ° C. The total concentration of all surfactants together is 0.05 to 5 wt .-% relative to the total amount of the aqueous Surfactant formulation, preferably 0.1 to 2.5 wt .-%. The person skilled in the art will make a suitable choice depending on the desired properties, in particular depending on the conditions in the petroleum formation. It will be appreciated by those skilled in the art that the concentration of surfactants may change upon injection into the formation because the formulation may mix with formation water or absorb surfactants also on solid surfaces of the formation. It is the great advantage of the mixture used according to the invention that the surfactants lead to a particularly good lowering of the interfacial tension. It is of course possible and also advisable to first produce a concentrate which is diluted on site to the desired concentration for injection into the formation. As a rule, the total concentration of the surfactants in such a concentrate is 10 to 45% by weight. Examples

Part I: Synthesis of the surfactants of the general formula (II)

General Procedure 1: Preparation of Guerbet Alcohol

In a 1 L flask or the alcohols (1 eq.) Are introduced and optionally melted at 50 ° C. KOH powder (0.24 eq.) And zinc oxide (5% by weight with respect to the starter alcohol) are added with stirring. The reaction mixture is heated as quickly as possible to 180-230 ° C and the resulting water of reaction is distilled off via a distillation outlet. For the fastest possible removal of the water of reaction, the glass flask is optionally insulated with aluminum foil. The reaction mixture is stirred for 6 to 30 hours at the given temperature. The resulting alcohol mixture is analyzed by gas chromatography and used without further work-up for the subsequent alkoxylation.

General Method 2: Alkoxylation by means of KOH catalysis (applies to the use of EO, PO and / or 1,2-BuO) In an autoclave, the alcohol (1, 0 eq) to be alkoxylated is optionally mixed with an aqueous KOH solution Contains 50 wt .-% KOH, added. The amount of KOH is 0.2 wt .-% of the product to be produced. With stirring, the mixture is dehydrated at 100 ° C and 20 mbar for 2 h. The mixture is then flushed three times with N ₂ , a pre-pressure of about 1, 3 bar N _{2 is} set and the temperature is increased to 120 to 130 ° C. The alkylene oxide is metered in so that the temperature between 125 ° C to 155 ° C (for ethylene oxide) and 130 to 145 ° C (for propylene oxide) and 125 to 145 ° C. (at 1, 2-butylene oxide) remains. The mixture is then stirred for 5 h at 125 to 145 ° C, rinsed with N ₂ , cooled to 70 ° C and the reactor emptied. The basic crude product is neutralized with acetic acid. Alternatively, the neutralization can be carried out with commercially available Mg silicates, which are then filtered off. The bright product is characterized by means of a ¹ H-NMR spectrum in CDCl ₃ , a gel permeation chromatography and an OH number determination, and the yield is determined.

General Procedure 3: Alkoxylation by DMC catalysis

In a 21 autoclave the alcohol to be alkoxylated (1, 0 eq) with a double metal cyanide catalyst (eg DMC catalyst from BASF type Zn-Co) is mixed at 80 ° C. To activate the catalyst is applied at 80 ° C for 1 h about 20 mbar. The amount of DMC is 0.1% by weight and less of the product to be produced. The mixture is then flushed three times with N ₂ , a pre-pressure of about 1.3 bar N _{2 is} set and the temperature is increased to 120 to 130 ° C. The alkylene oxide is metered in such that the temperature remains between 125 ° C to 135 ° C (for ethylene oxide) and 130 to 140 ° C (for propylene oxide) and 135 to 145 ° C (for 1, 2-butylene oxide). The mixture is then stirred for 5 h at 125 to 145 ° C, rinsed with N ₂ , cooled to 70 ° C and the reactor emptied. The bright product is characterized by means of a ¹ H-NMR spectrum in CDCl ₃ , a gel permeation chromatography and an OH number determination, and the yield is determined.

General Procedure 4: Sulfation by means of chlorosulfonic acid

In a round-bottomed flask, the alkyl alkoxylate (1, 0 eq) to be sulfated is dissolved in 1.5 times the amount of dichloromethane (on a weight percent basis) and cooled to 5-10 ° C. Thereafter, chlorosulfonic acid (1, 1 eq) is added dropwise so that the temperature does not exceed 10 ° C. The mixture is allowed to warm to room temperature and stirred under N ₂ flow at this temperature for 4 h, before the above reaction mixture is poured into a half-volume aqueous NaOH solution at max. 15 ° C is dropped. The amount of NaOH is calculated so that there is a slight excess with respect to the chlorosulfonic acid used. The resulting pH is about pH 9 to 10. The dichloromethane is added under a slight vacuum on a rotary evaporator at max. 50 ° C removed.

The product is characterized by ¹ H-NMR and determines the water content of the solution (about 80%). For the synthesis, the following alcohols were used. Alcohol description

C16C18 Commercially available fatty alcohol mixture consisting of linear

Ci ₆ H ₃₃ -OH and Ci ₈ H ₃₇ -OH

Alcohol description

C12C14 Commercially available fatty alcohol mixture consisting of linear C12H25-OH and C14H29-OH

Application testing

With the obtained surfactants, the following tests were carried out to evaluate their suitability for tertiary mineral oil production. Description of the measuring methods

Determination of SP ^*

a) Principle of Measurement: The interfacial tension between water and oil can be determined in a known manner by measuring the solubilization parameter SP ^* . The determination of the interfacial tension via the determination of the solubilization parameter SP ^* is a method accepted in the art for the approximate determination of the interfacial tension. The solubilization parameter SP ^* indicates how much ml of oil per ml of surfactant used is dissolved in a microemulsion (Windsor type III). The interfacial tension σ (interfacial tension, IFT) can be calculated from the approximate formula IFT "0.3 / (SP ^* ) ² if equal volumes of water and oil are used (C. Huh, J. Coli., Interf. Sc, Vol. 71, No. 2 (1979)). b) Working instructions

To determine the SP ^* , fill a 100 ml graduated cylinder with magnetic stirrer with 20 ml of oil and 20 ml of water. For this purpose, the concentrations of the respective surfactants are given. Subsequently, the temperature is gradually increased from 20 to 90 ° C, and it is observed in which temperature window forms a microemulsion.

The formation of the microemulsion can be visually observed or by means of conductivity measurements. It forms a three-phase system (upper phase Oil, medium phase microemulsion, lower phase water). If the upper and lower phases are the same size and no longer change over a period of 24 h, then the optimum temperature (T _opt ) of the microemulsion has been found. The volume of the middle phase is determined. From this volume, the volume of added surfactant is subtracted. The value obtained is then divided by two. This volume is now divided by the volume of added surfactant. The result is noted as SP ^* .

The type of oil and water used to determine SP ^* is determined according to the system under investigation. On the one hand petroleum itself can be used, or even a model oil such as decane. Both pure water and saline water can be used as water to better model the conditions in the oil formation. The composition of the aqueous phase can be adjusted, for example, according to the composition of a particular reservoir water.

Alternatively, interfacial tensions of crude oil in the presence of the surfactant solution at the particular temperature can be determined by spinning-drop method on an SVT20 from DataPhysics. For this purpose, an oil drop is injected into a capillary filled with saline surfactant solution at the respective temperature and the expansion of the drop is observed at approximately 4500 revolutions per minute until a constant value is established. This is usually the case after 2 hours. The interfacial tension IFT (or s H) is calculated here - as described by Hans-Dieter Dörfler in "Interfacial and Colloidal Disperse Systems" Springer Verlag Berlin Heidelberg 2002 - using the following formula from the cylinder diameter d _z , the speed w, and the density difference (drd ₂ ):

s ii = 0.25 ^■ d _z ^{3 ■} w 2 ^■ (dd ₂ )

test results

A 1: 1 mixture of decane and a NaCl solution with butyl diethylene glycol (BDG) is added. Butyl diethylene glycol (BDG) acts as a cosolvent and is not included in the calculation of SP ^* . For this purpose, a surfactant mixture of alkylalkoxysulfate and anionic surfactant is added. The total surfactant concentration is given in weight percent of the aqueous phase.

The results are shown in Table 1. Table 1 Experiments with Dean

a) surfactants of the formula (II) with ³ = n-Ci ₄ H ₂₉ , n-Ci ₆ H ₃ 3, R ⁴ = H, k = m = 7, o = 0, Y = S0 ₄ ^" and M ⁺ = Na ⁺ b) Petrostep S2, surfactant mixture of olefin sulfonates prepared by sulfonation of alkenes with internal double bond (C15H30, C16H32, C17H34 and C18H36) and subsequent neutralization with NaOH, main product are unsaturated aliphatic sulfonates, with the sulfonate group distributed along the carbon chain.

c) Surfactant mixture of olefin sulfonates prepared by sulfonation of alkenes with terminal double bond (C16H32 and C18H36) and subsequent neutralization with NaOH, main product are unsaturated aliphatic sulfonates, wherein the sulfonate group is attached to the terminal carbon atom. d) Mixture of 4 surfactants of the general formula (I) with different numbers of carbon atoms, the proportion of surfactants of the formula (I), in each case based on the radical RR ² CH- with 14 carbon atoms at 20-30 mol%, the proportion of surfactants of the formula (I) having 15 carbon atoms at 25-30 mol%, the proportion of surfactants of the formula (I) having 16 carbon atoms at 20-30 mol% and the proportion of surfactants of the formula (I) 17 carbon atoms at mole .-% 10-20%, in each case based on all radicals RR ² CH- of these 4 surfactants.

As can be seen in Example 5 when using the claimed surfactant of the formula (I), it is possible to achieve an ultra-low interfacial tension with respect to decane. In the comparative examples, the interfacial tension is always higher.

Table 2 Experiments with Dean

e) surfactants of the formula (II) where R = nC-ioHbi, nC-Hbs, R = n-Ci2H25, Π-ΟΜΗΣΘ, n = 7, m = 7, I = 1 0, o = 0, Y ^" = S0 ₄ ^" and M ⁺ = Na ⁺

d) Mixture of 4 surfactants of the general formula (I) with different numbers of carbon atoms, the proportion of surfactants of the formula (I), in each case based on the radical RR ² CH- with 14 carbon atoms at 20-30 mol%, the proportion of surfactants of the formula (I) having 15 carbon atoms at 25-30 mol%, the proportion of surfactants of the formula (I) having 16 carbon atoms at 20-30 mol% and the proportion of surfactants of the formula (I) having 17 carbon atoms at mol .-% 10-20%, in each case based on all radicals RR ² CH- of these 4 surfactants.

Example 6 shows that also other surfactant combinations of surfactant of formula (I) and formula (II) give ultra low interfacial tensions.

The following investigations were also carried out using the example of a deposit with heavy oil:

the crude oil has about 16 ° API

the deposit temperature is around 20 ° C

- And the reservoir water has about 16100 ppm TDS (total dissolved salt) on.

Na ₂ CO ₃ , alkyl ether sulfate of the formula (II), butyldiethylene glycol and 0.07% Sokalan® PA 20 (polyacrylate sodium salt) were added to a solution containing 12,000 ppm NaCl and 4100 ppm NaHCO ₃ . These solutions have been combined with claimed surfactants of the formula (I) as well as non-inventive anionic surfactants such as, for example, alkylbenzenesulfonates, internal olefinsulfonates or alcohol sulfate. In addition to the solubility of the surfactants, the interfacial tension of the surfactant formulation was measured against the crude oil. The total surfactant concentration and the amount of Na ₂ CO ₃ are based on the active substance and are given in percent by weight of the aqueous phase.

The test results are shown in the following tables. Table 3 Experiments with crude oil

f) Surfactants of formula (II) with R = n-C ₄ H ₂ 9, n-C ₆ H ₃ 3, R = H, n = 7, m = 7, 1 = 10, o = 0, Y ^"= S0 ₄ ^" and Na ⁺

g) surfactants of the formula (II) where R ³ = n-Ci ₄ H ₂₉ , n-Ci ₆ H ₃ 3, R ⁴ = H, n = 7, m = 7, I = 8, o = 0, Y ^" = S0 ₄ ^" and M ⁺ = Na ⁺

b) Petrostep S2, surfactant mixture of olefin sulfonates prepared by sulfonation of alkenes with internal double bond (C15H30, C16H32, Ci7H3 ₄ and C18H36) followed by neutralization with NaOH. The main product is unsaturated aliphatic sulfonates with the sulfonate group distributed along the carbon chain.

d) Mixture of 4 surfactants of the general formula (I) with different numbers of carbon atoms, the proportion of surfactants of the formula (I), in each case based on the radical RR ² CH- with 14 carbon atoms at 20-30 mol%, the proportion of surfactants of the formula (I) having 15 carbon atoms at 25-30 mol%, the proportion of surfactants of the formula (I) having 16 carbon atoms at 20-30 mol% and the proportion of surfactants of the formula (I) 17 carbon atoms at mole .-% 10-20%, in each case based on all radicals RR ² CH- of these 4 surfactants.

h) polyacrylic acid sodium salt As can be seen from Examples 8 and 9, it is also possible to achieve a low interfacial tension on a difficult crude oil (API grade below 20 °) with the aid of the claimed surfactants, which is better by a factor of 2 to 3 than in Comparative Example V7 , The surfactant solution is clear and allows easy injection into a porous rock of suitable permeability.

Table 4 Experiments with crude oil

Y ^" = S0 ₄ ^" and M ⁺ = Na ⁺

h) Polyacrylic Acid Sodium Salt As can be seen in Example 11, it is also possible to achieve a low interfacial tension on a difficult crude oil (API grade below 20 °) with the aid of the claimed surfactants, which is better by a factor of 3 than in the comparative example V10. The surfactant solution is clear and allows easy injection into a porous rock of suitable permeability. TABLE 5 Tests with light crude oil under high salinities

As can be seen from Example 12 of Table 5, a low interfacial tension of 0.007 mN / m can be achieved even with high salinities of 150000 ppm TDS on a simple crude oil (API grade of 33 °) with the aid of the claimed surfactants. The surfactant solution is very slightly scattering and allows injection into a porous rock of suitable permeability.

Claims

claims

1 . A process for oil production, by Winsor type III microemulsion flooding, in which an aqueous surfactant formulation containing a surfactant mixture to reduce the interfacial tension between oil and water to <0.1 mN / m, injected through at least one injection well into a Erdöllagersta- and the deposit by at least a production well crude oil is taken, characterized in that the surfactant mixture at least one secondary alkanesulfonate of the general formula (I)

I

HC-SO / b ^{Mb +} (I)

R o and at least one anionic surfactant of the general formula (II)

contains, where

each A ° independently for ethylene, propylene or butylene;

k is an integer from 1 to 99,

o for 0 or 1;

each M ^{b +} independently for a cation with the charge b;

b for 1, 2 or 3 and a stands for 1 or 2.

Method according to claim 1, characterized in that

R ^{3 is} a linear, saturated or unsaturated aliphatic hydrocarbon radical having 14 to 16 carbon atoms, and

R ^{4 is} a hydrogen atom.

Method according to claim 1, characterized in that

R ^{3 is} a linear, saturated or unsaturated aliphatic hydrocarbon radical having 10 or 12 carbon atoms, and

R ^{4 is} a linear, saturated or unsaturated aliphatic hydrocarbon radical having 12 or 14 carbon atoms.

Method according to claim 1, characterized in that

R ^{3 is} a linear, saturated or unsaturated aliphatic hydrocarbon radical having 14 or 16 carbon atoms, and

R ^{4 is} a linear, saturated or unsaturated aliphatic hydrocarbon radical having 16 or 18 carbon atoms.

Method according to one of claims 1 to 4, characterized in that in general formula (II) k is an integer in the range of 4 to 50.

Method according to one of claims 1 to 5, characterized in that in general formula (II) (OA °) _{k stands} for n butylene, m propylene and I ethyleneoxy groups, where n + m + I = k.

A method according to claim 6, characterized in that the n butylene, m propylene and I ethyleneoxy groups are arranged at least partially in blocks.

A method according to claim 6, characterized in that subsequent to the radical (R ³ ) (R ⁴ ) -CH-CH ₂ - in general formula (II) for (OA °) _k a Butylenoxyblock with n Butylenoxygruppen, followed by a Propylenoxyblock with m propylene-oxy groups and finally an ethyleneoxy block with I ethyleneoxy groups occurs.

9. The method according to any one of claims 6 to 8, characterized in that m is an integer from 4 to 15 and I is an integer from 0 to 25 and n is 0.

Method according to one of claims 6 to 8, characterized in that m is an integer from 4 to 15 and I is an integer from 0 to 25 and n is an integer from 1 to 15.

Method according to one of claims 1 to 10, characterized in that in general formula (II) the radical (OX) ₀ Y ^{a "} for OS (0) ₂ 0 ^" , OCH ₂ CH ₂ S (0) ₂ 0 ^" , OCH ₂ CH (OH) CH ₂ S (O) ₂ O ^" , 0 (CH ₂ ) ₃ S (0) ₂ 0 ^" , S (0) ₂ 0 ^" , CH ₂ C (0) 0 ^" or for CH ₂ CH (R ') C (0) 0 ^" , wherein R' is hydrogen or an alkyl radical having 1 to 4 carbon atoms.

Method according to one of claims 1 to 1 1, characterized in that the aqueous surfactant formulation in addition to the surfactant still at least one co-solvent selected from the group consisting of Butylmonoethylengly- kol, Butyldiethylenglykol, Butyltriethylenglykol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, n-pentanol and iso-pentanol.

Method according to one of claims 1 to 12, characterized in that the aqueous surfactant formulation in addition to the surfactant still contains at least one basic salt selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide and silicates.

Method according to one of claims 1 to 13, characterized in that the aqueous surfactant formulation in addition to the surfactant mixture also contains at least one chelating agent. 15. Surfactant mixture as specified in any one of claims 1 to 1 1.

16. Aqueous surfactant formulation as specified in any one of claims 1 to 14.

17. Use of an aqueous surfactant formulation according to claim 16 in oil production by means of Winsor type III microemulsion flooding.