CN102791824A - Process for mining mineral oil using butylene oxide-containing alkylalkoxylate-based surfactants - Google Patents

Abstract

The invention relates to a method for producing mineral oil by Winsor type III microemulsion flooding, wherein the oil comprises at least one general formula R¹-O-(D)_n-(B)_m-(A)_l-XY^-M⁺Aqueous surfactant of (2)The formulation is injected into a mineral oil reservoir via an injection well and crude oil is withdrawn from the reservoir via a production well.

Description

Process for mining mineral oil using butylene oxide-containing alkylalkoxylate-based surfactants

The present invention relates to a method for the recovery of mineral oil by Winsor III microemulsion flooding, wherein an aqueous surfactant formulation comprising at least one ionic surfactant of the general formula is injected into a mineral oil reservoir via an injection well, and extract crude oil from said reservoir via production wells:

R ¹ -O-(D) _n -(B) _m -(A) _l -XY ^- M ⁺

The present invention further relates to ionic surfactants of said general formula and methods for their extraction.

In natural mineral oil reservoirs, the mineral oil is present in the pores of porous reservoir rocks, which are sealed on the surface-facing side by an impermeable roof. The pores may be micropores, capillaries, pores, and the like. The pore necks may, for example, only have a diameter of approximately 1 μm. In addition to mineral oils (including natural gas components), oil reservoirs also contain water with high or low salt content.

In mineral oil mining, it is usually divided into primary mining, secondary mining and tertiary mining. In primary production, due to the autogenous pressure of the reservoir, the mineral oil automatically flows to the surface through the borehole after the drilling of the reservoir begins.

So secondary mining is used after primary mining. In secondary recovery, in addition to the boreholes for the extraction of mineral oil (so-called production wells), further boreholes are drilled in the mineral oil-bearing formation. Water is injected into the reservoir via these so-called injection wells to maintain the pressure or to raise it again. Due to the injection of water, the mineral oil is slowly pressed into the formation from the injection well in the direction of the production well through the pores. However, this only works if the pores are completely filled with oil and the more viscous oil is pushed forward by water. Once the moving water penetrates the pores, it follows the now path of least resistance, ie flows through the channels formed, and no longer pushes the oil forward.

Primary and secondary recovery typically only recovers about 30-35% of the amount of mineral oil present in the reservoir.

Mineral oil production is known to be further enhanced through tertiary oil recovery measures. A review of the three uses can be found, for example, in "Journal of Petroleum Science of Engineering 19 (1998)", pp. 265-280. Tertiary oil recovery includes, for example, thermal methods in which hot water or steam is injected into the oil reservoir. This makes the oil less viscous. The flow medium used may likewise be a gas such as _CO2 or nitrogen.

Tertiary mineral oil recovery also includes methods in which suitable chemicals are used as oil recovery aids. These can be used to influence the conditions at the end of the water flow, and thus also to extract mineral oils that are firmly held in the rock formation.

Near the end of secondary recovery, viscous and capillary forces act on the mineral oil trapped in reservoir rock pores, where the ratio of these two forces relative to each other depends on the microscopic oil separation. These forces are described by means of a dimensionless parameter, the so-called capillary number. The ratio of viscous force (velocity x driving phase viscosity) to capillary force (interfacial tension between oil and water x rock wetting):

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&mu;v</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}$

In this formula, μ is the viscosity of the fluid driving the mineral oil, v is the Darcy velocity (flow rate per unit area), σ is the interfacial tension between the liquid driving the mineral oil and the mineral oil, and θ is the mineral oil Contact angle with rock (C. Melrose, C.F. Brandner, J. Canadian Petr. Techn. 58, October-December 1974). The higher the capillary number, the higher the oil mobility and therefore the greater the oil removal.

Knowing that the capillary number near the end of secondary mineral oil recovery is about 10 ^-6 , the capillary number must be raised to about 10 ^-3 -10 ^-2 to enable the movement of additional mineral oil.

For this purpose, a specific form of flooding is implemented - known as Winsor Type III microemulsion flooding. In Winsor III microemulsion flooding, the injected surfactant should form Winsor III microemulsion with the water phase and oil phase existing in the reservoir. Winsor type III microemulsions are not emulsions with small droplets, but are thermodynamically stable liquid mixtures of water, oil, and surfactants. Its three advantages are:

- resulting in an extremely low interfacial tension σ between the mineral oil and the aqueous phase;

- they generally have a very low viscosity and are therefore not trapped by porous matrices;

- It is formed even at the lowest energy input and can remain stable for an infinite time (in contrast to this, conventional emulsions require high shear forces not normally found in oil reservoirs and are only kinetically stabilized).

Winsor III microemulsion is a balanced system of excess water and excess oil. Under these conditions for the formation of microemulsions, the surfactant covers the oil-water interface, and the lower the interfacial tension σ, the more favorable is the value <10 ⁻² mN/m (ultra-low interfacial tension). For best results, the proportion of microemulsions in the water-microemulsion-oil system should naturally be maximized at a defined amount of surfactant, since this results in lower interfacial tensions.

In this way the oil droplet shape can be changed (interfacial tension between oil and water is reduced to such an extent that minimal interfacial state and spherical shape are no longer favorable) and they can be driven through capillary openings by displacing water.

In the presence of excess surfactant, a Winsor type III microemulsion is formed when the oil-water interface is covered with surfactant. It thus constitutes a surfactant reservoir leading to a very low interfacial tension between the oil and water phases. Due to the low viscosity of Winsor type III microemulsions, they also migrate through porous reservoir rocks during oil displacement (in contrast, emulsions can become trapped in the porous matrix and plug the reservoir). When a Winsor type III microemulsion encounters an oil-water interface that has not been covered by a surfactant, the surfactant of the microemulsion can significantly reduce the interfacial tension of this new interface and cause oil movement (e.g. due to deformation of oil droplets). ).

The oil droplets can then merge with the continuous oil reservoir. This has two advantages:

First, as the continuous oil reservoir advances through new porous rock, oil droplets present therein can merge with the reservoir.

Furthermore, coalescence of the oil droplets to form an oil reservoir significantly reduces the oil-water interface and thus releases the no longer needed surfactant again. Thereafter, the surfactant released as described above can drive residual oil droplets in the formation into motion.

Therefore, Winsor III microemulsion flooding is a particularly effective method and requires much less surfactant than emulsion flooding methods. In microemulsion flooding, surfactants are usually injected, optionally together with co-solvents and/or alkaline salts, optionally together with chelating agents. Subsequently, a thickened polymer solution is injected to control fluidity. Another option is to inject a mixture of thickening polymer, surfactant, co-solvent, and/or alkaline salt (optionally with a chelating agent), and then inject a solution of thickening polymer to control flow. These solutions should usually be clear to prevent clogging of reservoirs.

Surfactant requirements for tertiary mineral oil development differ significantly from those for other applications: a suitable surfactant for tertiary oil recovery should balance the interfacial tension between water and oil (usually 20 mN/m) down to particularly low values of less than 10 ⁻² mN/m, thereby enabling adequate flow of the mineral oil. This must be achieved at reservoir temperatures, typically around 15-130°C, in the presence of water with a high salt content, more particularly also in the presence of high proportions of calcium and/or magnesium ions; the surfactants are therefore also Must be soluble in reservoir water with high salt content.

In order to meet these requirements, mixtures of surfactants, especially mixtures of anionic and nonionic surfactants, are frequently proposed.

US 3,890,239 discloses organic sulfonates with C ₈ -C ₂₀ -AO-H type (AO=oxyalkylene with 2-6 carbon atoms) alkyl alkoxylates with C ₈ -C ₂₀ -AO-sulfuric acid Combinations of anionic surfactants of the salt or C ₈ -C ₂₀ -AO-sulfonate type. Alkylene oxides are only described very generally in the context of the disclosure of US 3,890,239. However, there are only instances containing EO.

US 4,448,697 claims the use of alkyl alkoxylates of the C ₁ -C ₆ -(AO) _1-40 -EO _{≥ 10} -H type in combination with anionic surfactants. AO may be 1,2-butylene oxide or 2,3-butylene oxide.

US 4,460,481 describes surfactants of the alkylarylalkoxy sulfate or sulfonate type. The alkylene oxide may be ethylene oxide, propylene oxide or butylene oxide. Provided that ethylene oxide constitutes the majority of the alkylene oxide. Butylene oxide is not described in more detail.

Thus, the person skilled in the art adjusts the application parameters, such as surfactant type, concentration and mixing ratio relative to each other, according to the conditions present in a given reservoir, such as temperature and salt content.

As mentioned above, mineral oil recovery is proportional to capillary number. The lower the interfacial tension between oil and water, the higher the capillary number. The higher the average value of carbon atoms in crude oil, the more difficult it is to achieve low interfacial tension. Suitable surfactants for lowering interfacial tension are those with long chain alkyl groups. The longer the alkyl chain, the better the interfacial tension reduction effect. However, the availability of such compounds is very limited.

It is therefore an object of the present invention to provide a particularly effective surfactant for surfactant flooding and an improved method for the tertiary recovery of mineral oil.

Accordingly, there is provided a method for tertiary recovery of mineral oil by Winsor III microemulsion flooding, wherein an aqueous surfactant formulation comprising at least one ionic surfactant is injected into a mineral oil reservoir via at least one injection well to the interfacial tension between oil and water is reduced to a value <0.1 mN/m, preferably <0.05 mN/m, more preferably <0.01 mN/m, and crude oil is extracted from said reservoir via at least one production well, Wherein said surfactant formulation comprises at least one surfactant of the following general formula:

R ¹ -O-(D) _n -(B) _m -(A) _l -XY ^- M ⁺

in

^R is a straight-chain or branched, saturated or unsaturated aliphatic and/or aromatic hydrocarbon group having 8-30 carbon atoms,

A is ethyleneoxy,

B is propylene oxide,

D is butyleneoxy,

l is 0-99,

m is 0-99,

n is 1-99,

X is a hydrocarbyl or hydrocarbylene group having 0-10 carbon atoms,

M ⁺ is a cation,

Y ^- selected from sulfate, sulfonate, carboxylate and phosphate,

Wherein the A, B and D groups can be randomly distributed, alternately distributed or in any order of two, three, four or more blocks, and the sum of l+m+n is 3-99, 1, The proportion of 2-butene oxide is at least 80%, based on the total amount of butylene oxide.

There is also provided a surfactant mixture for mineral oil recovery comprising at least one ionic surfactant of the general formula as defined above.

The present invention should be described in detail below:

In the above-described method of the invention for the recovery of mineral oil by microemulsion flooding of Winsor III type, an aqueous surfactant formulation comprising at least one surfactant of the general formula is used. Furthermore, it may contain other surfactants and/or other components.

In the method of the present invention for tertiary exploitation of mineral oil by Winsor III type microemulsion flooding, use the surfactant of the present invention to reduce the interfacial tension between oil and water to <0.1mN/m, preferably <0.05mN/m, more preferably < A value of 0.01 mN/m. Therefore, the interfacial tension between oil and water is reduced to a value of 0.1-0.0001 mN/m, preferably 0.05-0.0001 mN/m, more preferably 0.01-0.0001 mN/m.

The general formula R ¹ -O-(D) _n -(B) _m -(A) _l -XY ^- M ⁺ may encompass at least one surfactant. For manufacturing reasons, it is also possible for a plurality of different surfactants of the general formula to be present in the surfactant formulation.

The ^R group is a straight-chain or branched aliphatic and/or aromatic hydrocarbon group having 8-30 carbon atoms, preferably 9-30 carbon atoms, more preferably 10-28 carbon atoms.

In a particularly preferred embodiment of the invention, the ^R group is _isoC17H35 or _{a commercially} available fatty alcohol mixture consisting _of linear _C16H33 and _C18H37 or derived from a commercially available _C16 Guerbet alcohol2 - Hexyldec-1-ol or derived from the commercially available C ₂₄ Guerbet alcohol 2-decyltetradecanol or derived from the commercially available C ₂₈ Guerbet alcohol 2-dodecylhexadecanol.

More preferably, in straight chain alcohols n=3-10 and m=5-9, and in branched alcohols n=2-10 and m=5-9. Here in each case it is preferred that D is more than 80% 1,2-butylene oxide, and starting from the alcohols, the alkylene oxides have the sequence D—B—A. More than 90% of the alkylene oxides are arranged in blocks.

Especially preferred are straight-chain or branched aliphatic hydrocarbon groups, especially straight-chain or branched aliphatic hydrocarbon groups having 10 to 28 carbon atoms.

The degree of branching of the branched aliphatic hydrocarbon group is usually 0.1-5.5, preferably 1-3.5. Here, the term "degree of branching" is defined in a manner known in principle as the number of methyl groups in an alcohol molecule minus one. The average degree of branching is the statistical average of the degree of branching of all molecules in the sample.

In the above formula, A means ethyleneoxy. B means propyleneoxy and D means butyleneoxy.

In the general formula defined above, l, m and n are each an integer. However, it is clear to a person skilled in the art of polyalkoxylates that this definition is in each case that of a single surfactant. In the case where there is a mixture of surfactants or a formulation of surfactants comprising a plurality of surfactants of the general formula, the numbers l, m and n are each an average value of all molecules of said surfactant, since The alkoxylation of alcohols with ethylene oxide and/or propylene oxide and/or butylene oxide results in each case with a distribution of chain lengths. This distribution can be described by the polydispersity D in a manner known in principle. D=Mw/Mn is the quotient of the weight average molar mass and the number average molar mass. Polydispersity can be determined by methods known to those skilled in the art, for example by gel permeation chromatography.

In the above general formula, l is 0-99, preferably 1-40, more preferably 1-20.

In the above general formula, m is 0-99, preferably 1-20, more preferably 5-9.

In the above general formula, n is 1-99, preferably 2-30, more preferably 2-10.

According to the present invention, the sum of l+m+n is 3-99, preferably 5-50, more preferably 8-39.

According to the invention, the proportion of 1,2-butyleneoxy groups, based on the total amount of butyleneoxy groups (D), is at least 80%, preferably at least 85%, preferably at least 90%, more preferably at least 95% of 1,2-butyleneoxy groups .

Ethyleneoxy (A), propyleneoxy (B) and butyleneoxy (D) are randomly distributed, alternately distributed or in any order of two, three, four, five or more embedded segment form.

In a preferred embodiment of the invention, in the presence of a plurality of different alkyleneoxy blocks, the sequence of R1 is preferably butyleneoxy block, propyleneoxy block, ethyleneoxy block. The butyleneoxy groups used should contain >80% 1,2-butylene oxide, preferably >90% 1,2-butylene oxide.

In the above general formula, X is an alkylene or alkenylene group having 0-10, preferably 0-3 carbon atoms. Alkylene is preferably methylene, ethylene or propylene.

In the cited prior art, there is generally no specific descriptive information for C ₄ epoxides. This can generally mean 1,2-butylene oxide, 2,3-butylene oxide, butylene isooxide and mixtures of these compounds. The composition generally depends on the _C4 olefins used and to some extent on the oxidation method.

In the above general formula, Y is sulfonate, sulfate, carboxylate or phosphate.

In the above general formula, M ⁺ is a cation, preferably a cation selected from Na ⁺ , K ⁺ , Li ⁺ , NH ₄ ⁺ , H ⁺ , Mg ²⁺ and Ca ²⁺ .

The surfactants of the general formula can be prepared in a manner known in principle by alkoxylation of the corresponding alcohols R ¹ —OH. The implementation of this alkoxylation is known in principle to the person skilled in the art. It is likewise known to those skilled in the art that the molecular weight distribution of alkoxylates can be influenced by the reaction conditions, especially the choice of catalyst.

The surfactants of the general formula can preferably be prepared by base-catalyzed alkoxylation. In this case, the alcohol R ¹ -OH can be mixed with an alkali metal hydroxide (preferably potassium hydroxide) or an alkali metal alkoxide (eg sodium methoxide) in a pressurized reactor. Water still present in the mixture can be removed by means of reduced pressure (eg <100 mbar) and/or increased temperature (30-150° C.). Thereafter, the alcohol is present in the form of the corresponding alkoxide. Then, inert with an inert gas (for example nitrogen) and gradually add the alkylene oxide at a temperature of 60-180° C. and a pressure of up to 10 bar. In a preferred embodiment, the alkylene oxide is initially metered in at 130° C. During the course of the reaction, the temperature rose to 170 °C due to the release of heat from the reaction. In other preferred embodiments of the invention, butylene oxide is first added at a temperature of 135-145°C, then propylene oxide is added at a temperature of 130-145°C, and then propylene oxide is added at a temperature of 125-145°C Ethylene oxide. At the end of the reaction, the catalyst can be neutralized, for example, by adding an acid such as acetic acid or phosphoric acid and, if desired, filtered off.

However, the alkoxylation of the alcohols R ¹ —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 43 25 237 A1 or double metal cyanide catalysts (DMC catalysts). Suitable DMC catalysts are disclosed, for example, in DE 10243361 A1, especially paragraphs [0029] to [0041] and the literature cited therein. For example, a Zn-Co type catalyst can be used. To carry out the reaction, the alcohol R ¹ -OH can be mixed with the catalyst, the mixture can be dehydrated as described above and reacted with the alkylene oxide as described. Typically not more than 1000 ppm of catalyst, based on the mixture, is used, which may remain in the product due to this small amount. Catalyst amounts typically may be less than 1000 ppm, such as 250 ppm or less.

Anionic groups are introduced first. This is known in principle to the person skilled in the art. In the case of sulfate, it is possible, for example, to use reaction with sulfuric acid, chlorosulfonic acid or sulfur trioxide in a falling film reactor, followed by neutralization. In the case of sulfonates, for example reaction with propane sultone, followed by neutralization with butane sultone, followed by vinylsulfonic acid sodium salt or 3-chloro-2-hydroxypropanesulfonic acid sodium salt neutralize. In the case of carboxylates, for example, alcohols can be oxidized with oxygen and subsequently neutralized, or reacted with sodium chloroacetate.

other surfactants

In addition to the surfactants of the abovementioned general formulas, the formulations may optionally additionally comprise further surfactants. These are, for example, anionic surfactants of the alkylarylsulfonate or olefinsulfonate (α-olefinsulfonate or internal olefinsulfonate) type and/or of the alkylethoxylate or alkylpolyglucoside type Nonionic surfactant. These further surfactants may also be especially oligomeric or polymeric surfactants. Such polymeric cosurfactants are advantageously used to reduce the amount of surfactant required to form the microemulsion. Accordingly, such polymeric cosurfactants are also referred to as "microemulsion builders". Examples of such polymeric surfactants include amphiphilic block copolymers comprising at least one hydrophilic block and at least one hydrophobic block. Examples include polyoxypropylene-polyoxyethylene block copolymers, polyisobutylene-polyoxyethylene block copolymers, and comb-like copolymers having ethylene oxide side chains and a hydrophobic backbone, wherein the backbone preferably consists essentially of Olefins or (meth)acrylates as monomers. Here, the term "polyethylene oxide" shall in each case include polyethylene oxide blocks comprising propylene oxide units as defined above. Further details of such surfactants are disclosed in WO2006/131541A1.

Mineral Oil Extraction Methods

In the mineral oil recovery method of the present invention, a suitable aqueous formulation of the surfactant of the general formula is injected into a mineral oil reservoir via at least one injection well, and crude oil is extracted from said reservoir via at least one production well. In the context of the present invention, the term "crude oil" of course does not mean a single-phase oil, but a usual crude oil-water emulsion. In general, a reservoir usually has several injection wells and several production wells.

The main function of the surfactant is to reduce the interfacial tension between water and oil - preferably to a value significantly < 0.1 mN/m. After injection of said surfactant formulation (known as "surfactant flooding") or preferably Winsor type III "microemulsion flooding", it can be achieved by injecting water ("waterflooding") or preferably with a significant thickening effect A higher viscosity aqueous solution of polymer ("polymer flood") is injected into the formation to maintain pressure. However, techniques are also known in which the surfactant is first allowed to act on the formation. Another known technique is to inject a solution of surfactant and thickening polymer, followed by injecting the thickening polymer solution. Those skilled in the art know the details of the industrial implementation of "surfactant flooding", "water flooding" and "polymer flooding" and use the appropriate technique depending on the reservoir type.

For the process according to the invention, aqueous formulations of surfactants of the general formula are used. In addition to water, the formulations may optionally comprise water-miscible or at least water-dispersible organic or other substances. Such additives are used inter alia to stabilize surfactant solutions during storage or transport to the oil field. However, the amount of such other solvents should generally not exceed 50% by weight, preferably 20% by weight. In a particularly advantageous embodiment of the invention, only water is used for formulation. Examples of water-miscible solvents include alcohols such as methanol, ethanol, propanol, butanol, sec-butanol, pentanol, butyl glycol, butyl diethylene glycol or butyl triethylene glycol, among others.

According to the invention, the proportion of surfactants of the general formula to all surfactants present (ie surfactants of the general formula and optionally present surfactants) is at least 30% by weight. Preferably this proportion is at least 50% by weight.

The mixtures used according to the invention can preferably be used for surfactant flooding of oil reservoirs. Especially suitable for Winsor III microemulsion oil flooding (oil flooding in the range of Winsor III or oil flooding in the range of bicontinuous microemulsion phases). The technique of microemulsion flooding has been described in detail in the introduction.

Besides the surfactants, the formulations may also comprise other components, such as C ₄ -C ₈ alcohols and/or alkaline salts (so-called “alkaline surfactant flooding”). Such additives are useful, for example, to reduce retention in the formation. The ratio of alcohol, based on the total amount of surfactant used, is generally at least 1:1—however, it is also possible to use a significant excess of alcohol. The amount of basic salt may generally range from 0.1 to 5% by weight.

The reservoir in which the method is used typically has a temperature of at least 10°C, such as 10-150°C, preferably at least 15°C to 120°C. The total concentration of all surfactants together is from 0.05 to 5% by weight, preferably from 0.1 to 2.5% by weight, based on the total amount of the aqueous surfactant formulation. A person skilled in the art makes an appropriate choice according to the desired properties, especially according to the conditions in the mineral oil formation. At this point, it will be apparent to those skilled in the art that the concentration of the surfactant may vary after injection into the formation because the formulation may be mixed with the formation water, or the surfactant may also be absorbed on the solid surface of the formation. A great advantage of the mixtures used according to the invention is that the surfactants lead to a particularly good lowering of the interfacial tension.

It is of course possible and desirable to first prepare the concentrate only diluted in situ to the desired concentration for injection into the formation. The total concentration of surfactants in the concentrate is typically 10-45% by weight.

The following examples are intended to illustrate the invention in detail:

Part I: Synthesis of Surfactants

General method 1: Catalyzed alkoxylation by KOH (applicable when using EO, PO and/or 1,2-BuO)

In a 2 L autoclave, the alcohol to be alkoxylated (1.0 equiv) was mixed with an aqueous KOH solution containing 50% by weight KOH. The amount of KOH is 0.2% by weight of the product to be prepared. With stirring, the mixture was dehydrated at 100° C. and 20 mbar for 2 hours. Then, purge with _N2 3 times, establish a _N2 inlet pressure of about 1.3 bar, and raise the temperature to 120-130 °C. such that the temperature is maintained at 125-135°C (in the case of ethylene oxide) or 130-140°C (in the case of propylene oxide) or 135-145°C (in the case of 1,2-butylene oxide ) to meter in the alkylene oxide. It was then stirred at 125-145 °C for an additional 5 h, purged with _N2 , cooled to 70 °C, and the autoclave was emptied. The basic crude product is neutralized with the aid of acetic acid. Alternatively, it can be neutralized with commercially available magnesium silicate, and then filtered off. The light-colored product is characterized by means of ¹ H-NMR spectroscopy in CDCl ₃ , gel permeation chromatography and OH number determination, and the yield is determined.

General method 2: Catalyzed alkoxylation by DMC (in the case of 2,3-butylene oxide)

In a 2 L autoclave at 80°C, the alcohol to be alkoxylated (1.0 eq.) was mixed with a double metal cyanide catalyst (eg Zn-Co type DMC catalyst from BASF). To activate the catalyst, apply about 20 mbar for 1 hour at 80°C. The amount of DMC is 0.1% by weight or less of the product to be prepared. Then, purge with _N2 3 times, establish a _N2 inlet pressure of about 1.3 bar, and raise the temperature to 120-130 °C. such that the temperature is maintained at 125-135°C (in the case of ethylene oxide) or 130-140°C (in the case of propylene oxide) or 135-145°C (in the case of 2,3-butylene oxide ) to meter in the alkylene oxide. It was then stirred at 125-145 °C for an additional 5 h, purged with _N2 , cooled to 70 °C, and the autoclave was emptied. The light-colored product is characterized by means of ¹ H-NMR spectroscopy in CDCl ₃ , gel permeation chromatography and OH number determination, and the yield is determined.

General Method 3: Sulfation by Chlorosulfonic Acid

In a 1 L round bottom flask, the alkyl alkoxylate to be sulfated (1.0 equivalent) was dissolved in 1.5 times the amount of dichloromethane (based on weight %) and cooled to 5-10°C. Thereafter, chlorosulfonic acid (1.1 equivalents) was added dropwise in such a manner that the temperature did not exceed 10°C. The mixture was allowed to warm to room temperature and stirred at this temperature under a flow of _N2 for 4 h, then the above reaction mixture was added dropwise to half volume of aqueous NaOH at a maximum of 15 °C. The amount of NaOH was calculated to obtain a slight excess based on the chlorosulfonic acid used. The resulting pH was about pH 9-10. The dichloromethane was removed under gentle vacuum on a rotary evaporator up to 50°C.

The product was characterized by ¹ H-NMR, and the water content of the solution was determined (about 70%).

The following alcohols were used for the synthesis.

Performance Testing

The following tests were carried out using the obtained surfactants to assess their suitability for tertiary recovery of mineral oils.

Test method description

Measurement of SP ^*

a) Measuring principle:

The interfacial tension between water and oil is determined in a known manner by determining the solubilization parameter SP ^* . The method of measuring the interfacial tension by measuring the solubilization parameter SP ^* is an industry-accepted method for approximately measuring the interfacial tension. The solubilization parameter SP ^* characterizes the mL of oil dissolved in each mL of surfactant used in the microemulsion (Winsor type III). If equal volumes of water and oil are used, the interfacial tension σ(IFT) can thus be calculated by the approximate formula IFT≈0.3/(SP ^* ) ² (C.Huh, J.Coll.Interf.Sc., Vol. 71 No. 2 Issue (1979)).

b) procedure

To determine SP ^* , a 100 mL test cylinder with a magnetic stir bar was filled with 20 mL of oil and 20 mL of water. A certain concentration of a specific surfactant is added thereto. Then, the temperature was gradually increased from 20°C to 90°C, and the temperature window for microemulsion formation was observed.

The formation of microemulsions can be assessed visually or by means of conductivity measurements. A three-phase system (upper oil phase, middle microemulsion phase, lower water phase) is formed. The _optimum temperature for microemulsion formation (Topt) was determined when the upper and lower phases had the same size and did not change within 12 hours. Measure the mesophase volume. Subtract the added surfactant volume from this volume. Then divide the resulting value by 2. This volume is then divided by the volume of surfactant added. Results are counted as SP ^* .

The type of oil and water used to determine SP ^* depends on the system to be tested. Mineral oil itself or a simulated oil such as decane can be used. The water used can be pure water and brine to better simulate conditions in mineral oil formations. The composition of the aqueous phase can be adjusted, for example, according to the composition of a particular reservoir water.

Information on the aqueous and oil phases used can be found in the specific description of the test below.

Test Results

A 1:1 mixture of decane and NaCl solution was mixed with butyldiglycol (BDG). Butyl diglycol (BDG) was used as a co-solvent and was not included in the calculation of SP ^* . To this was added a surfactant mixture consisting of 3 parts of alkylalkoxysulfate and 1 part of dodecylbenzenesulfonate (Lutensit A-LBN 50 from BASF). The total concentration of the surfactants is in % by weight of the total volume.

Additionally, a 1:1 mixture of decane and NaCl solution was mixed with butyldiglycol (BDG). Butyldiglycol (BDG) was used as a co-solvent and was not included in SP ^* . A surfactant mixture consisting of 3 parts of alkylalkoxysulfate and 1 part of secondary alkylsulfonate (Hostapur SAS 60 from BASF) was added. The total surfactant concentration in % by weight is relative to the aqueous phase.

Additionally, a 1:1 mixture of southern German crude oil (API 33°) and NaCl solution was mixed with butyldiglycol (BDG). Butyl diglycol (BDG) was used as a co-solvent and was not included in the calculation of SP ^* . To this was added a surfactant mixture consisting of 3 parts of alkylalkoxysulfate and 1 part of dodecylbenzenesulfonate (Lutensit A-LBN 50 from BASF). The total concentration of the surfactants is in % by weight of the total volume.

In two other tests, a 1:1 mixture of crude oil (API 33°) and NaCl solution obtained from southern Germany or a 1:1 mixture of crude oil (API 14°) and NaCl solution from southern Germany were each mixed with butyl di glycol (BDG) mix. Butyldiglycol (BDG) was used as a co-solvent and was not included in SP ^* . A surfactant mixture consisting of 3 parts of alkylalkoxysulfate and 1 part of secondary alkylsulfonate (Hostapur SAS 60 from Clariant) was added each. The total concentration of said surfactants in each % by weight is relative to the aqueous phase.

The results for surfactants based on linear and branched alcohols are shown in Tables 1-7.

Table 1 Surfactants based on linear C ₁₆ C ₁₈ alcohols

As evident from examples C1 and C3 or C2 and C4 of Table 1, there is little difference in the SP ^* of C ₁₆ C ₁₈ -7PO-sulfate and C ₁₆ C ₁₈ -9PO-sulfate. In this regard, it should be noted that comparisons should be made at similar _Toptimum to rule out temperature effects. In the case of surfactants with nonionic components these can have a considerable effect.

Surprising results were obtained when using BuO-containing C ₁₆ C ₁₈ -alkoxysulfates. Examples 5 and 6 show that the introduction of two 1,2-butylene oxide units between the C ₁₆ C ₁₈ -fatty alcohol and the seven oxypropylene units leads to impressive results at both 47°C and 62°C. Surprise Stable SP ^* =16. A similar situation occurs when the total concentration of surfactant is reduced. In Example 11, the SP ^* was 15 at 72°C. The pure PO-containing compounds with the same degree of alkoxylation showed a larger change (C3 and C4), or a slightly larger decrease in SP ^* (C9 and C10) when the total surfactant concentration was reduced.

In contrast, the presence of a 1,2-butylene oxide alignment between the propylene oxide block and the sulfate group is less favorable, as in comparative examples C7 and C8. SP ^* is at a slightly lower level and its variation is more pronounced when temperature differences are taken into account.

Significantly worse with 2,3-butylene oxide. As can be seen in C12, the SP ^* is essentially half (SP ^* = 8) and therefore worse than the alkyl propoxysulfate (C9) with the same degree of alkoxylation. Surprisingly, not only the number of carbon atoms but also their spatial arrangement has a great influence on the ability of the surfactant to lower the interfacial tension. As in the case of 2,3-butylene oxide, the unfavorable alignment actually has a disruptive effect and worse values are obtained than in the case of the corresponding surfactant without the alkylene oxide having 4 carbon atoms. This is not described in US3890239 or US4448697.

Interestingly, in linear _C16C18 fatty alcohols, a sudden improvement occurs once the content _of 1,2-butylene oxide units is three or more. In Example 13, the introduction of three such units resulted in an increase in SP ^* to 23.5. This can be increased even further by reaching 5 units (Examples 14-16). At this point, SP ^* is even higher than 30.

Table 2 Surfactants based on branched iso-C ₁₇ alcohols

Similar situations exist in Table 2. At this point, branched isoC ₁₇ -alcohol based alkyl alkoxysulfates were used to verify that the presence of influences that could not be attributed solely to linear alcohols.

The comparison of Example C1 and Example 2 shows very clearly the clear advantage of using 1,2-butylene oxide instead of propylene oxide among surfactants with the same degree of alkoxylation. At similar temperatures, the SP ^* is three times higher. The direct arrangement of 1,2-BuO on the alkyl moiety (Examples 5 and 6) also resulted in lower interfacial tension than a different arrangement (eg Example 4).

Table 3 Comparison of branched C ₁₆ Guerbet alcohol-based surfactants and C ₁₆ C ₁₈ -alcohol-based surfactants

It can be seen from Table 3 that a similar situation occurs. If the linear alcohol-based surfactant contains more than 2 1,2-BuO units, the SP ^* rises significantly, thus reducing the interfacial tension. Compared with Examples 3 and 4, Example 2 shows the difference between surfactants based on linear C ₁₆ C ₁₈ -alcohols and branched C ₁₆ Guerbet alcohols. In Guerbet-based surfactants, the introduction of 2 1,2-butylene oxide units has resulted in significantly better SP ^* than surfactants based on linear alcohols with similar chain lengths. However, it can be seen from Example 5 that in the case of straight-chain alcohols, introducing a larger amount of 1,2-butylene oxide can obtain approximately the same SP ^* as in Example 4.

As can be seen from Example 6, the introduction of 10 EOs between the sulfate group and the PO block can substantially compensate for the additional hydrophobicity of the 7-BuO block; therefore, it can be used under similar conditions (similar salt content, similar temperature T _best ) compared with the control example C1.

From comparative examples C7 and C8, it can be seen that without the introduction of 1,2-butylene oxide, the surfactant is only an average surfactant. Example 11 shows that the introduction of 1 equivalent of 1,2-BuO improves SP ^* only to a certain extent. In the case of C ₁₆ Guerbet-based surfactants (Example 3), the SP ^* was significantly improved with the introduction of only 2 equivalents of 1,2-BuO.

Table 4 Tested using crude oil from southern Germany

As can be seen from Table 4, compared with the test using decane simulant oil, basically the same situation was obtained using crude oil. At comparable temperatures, Comparative Example C1 achieves significantly lower SP ^* and thus higher interfacial tension than the BuO-containing surfactant in Example 2. Comparative Example C3 and Example 4 show the advantages of 1,2-butylene oxide in a similar manner.

Table 5 Tests using decane at similar temperatures and salinities

It is clear that aqueous surfactant solutions mixed with BDG are soluble under optimal conditions (salinity, _Topt , which is obtained by adding oil to a 3-phase system (Winsor type III)). As shown in Table 5, the optimum conditions (salinity, _Topt ) are very close. As shown in Example 2, the correct fine-tuning of the degree of alkoxylation yields a surfactant with a similar hydrophilic-hydrophobic balance to the surfactant in Example VI. The SP ^* in Example 2 is higher. Therefore the interfacial tension is much lower.

Table 6 Tests at similar temperature and salinity using crude oil (API 33°) obtained from Germany

It is clear that the aqueous surfactant solution mixed with BDG is soluble under the optimum conditions (salinity, _Topt , which is obtained by adding oil to a 3-phase system (Winsor type III). As shown in Table 6, the optimum The conditions (salinity, _Topt ) were very close. As shown in Example 2, correct fine-tuning of the degree of alkoxylation yielded a surfactant with a similar hydrophilic-hydrophobic balance to the surfactant in Example V1. Implementation The SP ^* is also much higher in Example 2. So the interfacial tension is much lower.

Table 7 Tests of crude oil (API 14) obtained from Canada at similar temperature and salinity

It is clear that aqueous surfactant solutions mixed with BDG are soluble under optimal conditions (salinity, _Topt , which is obtained by adding oil to a 3-phase system (Winsor type III)). As shown in Table 7, the optimum conditions (salinity, _Topt ) are very close. As shown in Example 2, the correct fine-tuning of the degree of alkoxylation yields a surfactant with a similar hydrophilic-hydrophobic balance to the surfactant in Example VI. The SP ^* in Example 2 is also much higher. Therefore the interfacial tension is much lower.

Claims (16)

1. A method of producing mineral oil by Winsor III type microemulsion flooding, wherein the aqueous surface active agent comprising at least one ionic surfactant for reducing the interfacial tension between oil and water to <0.1mN/m A surfactant formulation is injected into a mineral oil reservoir via at least one injection well, and crude oil is withdrawn from said oil reservoir via at least one production well, wherein the surfactant formulation comprises at least one surfactant of the general formula: R ¹ -O-(D) _n -(B) _m -(A) _l -XY ^- M ⁺ in ^R is a straight-chain or branched, saturated or unsaturated aliphatic and/or aromatic hydrocarbon group having 8-30 carbon atoms, A is ethyleneoxy, B is propylene oxide, D is butyleneoxy, l is 0-99, m is 0-99, n is 1-99, X is a hydrocarbyl or hydrocarbylene group having 0-10 carbon atoms, M ⁺ is a cation, and Y ^- is selected from sulfate group, sulfonate group, carboxylate group and phosphate group, wherein A, B and D groups can be randomly distributed, alternately distributed or in any order in the form of two, three, four or more blocks, the sum of l+m+n is 3-99, and 1, The proportion of 2-butene oxide is at least 80%, based on the total amount of butylene oxide. 2. The method according to claim 1, wherein the sum of l+m+n is 5-50. 3. The process according to claim 1 or 2, wherein the proportion of 1,2-butene oxide is at least 90%, based on the total amount of butylene oxide. 4. The method according to any one of claims 1-3, wherein the surfactant of the general formula comprises 2-15 1,2-butylene oxide units. 5. The method according to any one of claims 1-4, wherein the concentration of all surfactants together is 0.05-5% by weight, based on the total amount of the aqueous surfactant formulation. 6. The method according to any one of claims 1-4, wherein: m is 5-9, n is 2-10, and Y ^- is selected from sulfate group, sulfonate group and carboxylate group, wherein More than 80% of the A, B and D groups exist in the form of blocks in the order of D, B and A starting from R ¹ , and the sum of l+m+n is 7-49, 1,2-butylene oxide The proportion of is at least 90% based on the total amount of butylene oxide in the molecule. 7. The method according to claim 6, wherein R ¹ is a straight chain fatty alcohol having 16 or 18 carbon atoms and n is 3-10. 8. A surfactant formulation comprising at least one ionic surfactant of the general formula: R ¹ -O-(D) _n -(B) _m -(A) _l -XY ^- M ⁺ in ^R is a straight-chain or branched, saturated or unsaturated aliphatic and/or aromatic hydrocarbon group having 8-30 carbon atoms, A is ethyleneoxy, B is propylene oxide, D is butyleneoxy, l is 0-99, m is 0-99, n is 1-99, X is a hydrocarbyl or hydrocarbylene group having 0-10 carbon atoms, M ⁺ is a cation, and Y ^- is selected from sulfate group, sulfonate group, carboxylate group and phosphate group, wherein A, B and D groups can be randomly distributed, alternately distributed or in any order in the form of two, three, four or more blocks, the sum of l+m+n is 3-99, and 1, The proportion of 2-butene oxide is at least 80%, based on the total amount of butylene oxide. 9. A surfactant formulation according to claim 8, wherein: m is 5-9, n is 2-10, and Y ^- is selected from sulfate group, sulfonate group and carboxylate group, wherein More than 80% of the A, B and D groups exist in the form of blocks in the order of D, B and A starting from R ¹ , the sum of l+m+n is 7-49, and 1,2-butylene oxide The proportion of alkenes is at least 90%, based on the total amount of butylene oxide in the molecule. 10. The surfactant formulation according to claim 9, wherein R ¹ is a linear fatty alcohol having 16 or 18 carbon atoms and n is 3-10. 11. The surfactant formulation according to any one of claims 8-10, wherein the concentration of all surfactants together is 0.05-5% by weight, based on the total amount of the aqueous surfactant formulation. 12. A surfactant of the general formula, R ¹ -O-(A) _l -(B) _m (D) _n -XY ^- M ⁺ in ^R is a straight-chain or branched, saturated or unsaturated aliphatic and/or aromatic hydrocarbon group having 8-30 carbon atoms, A is ethyleneoxy, B is propylene oxide, D is butyleneoxy, l is 0-99, m is 0-99, n is 1-99, X is a hydrocarbyl or hydrocarbylene group having 0-10 carbon atoms, M ⁺ is a cation, and Y ^- is selected from sulfate group, sulfonate group, carboxylate group and phosphate group, wherein A, B and D groups can be randomly distributed, alternately distributed or in any order in the form of two, three, four or more blocks, the sum of l+m+n is 3-99, and 1, The proportion of 2-butene oxide is at least 80%, based on the total amount of butylene oxide. 13. The surfactant according to claim 12, wherein the sum of l+m+n is 3-49. 14. The surfactant according to claim 12 or 13, wherein the proportion of 1,2-butene oxide is at least 90%, based on the total amount of butylene oxide. 15. The surfactant according to any one of claims 12-14, wherein ^R is a linear or branched, saturated or unsaturated aliphatic and/or aromatic hydrocarbon group having 10-30 carbon atoms. 16. A surfactant according to any one of claims 12-15, wherein: ^R is a straight-chain fatty alcohol with 16 or 18 carbon atoms, m is 5-9, n is 3-10, and Y ^- selected from sulfate, sulfonate and carboxylate, wherein more than 80% of the A, B and D groups exist in the form of blocks in the order of D, B and A starting from R ¹ , the sum of l+m+n is 7-49, and 1,2-oxidation The proportion of butene is at least 90%, based on the total amount of butylene oxide in the molecule.