Surfactants, processes for their preparation and use, inverse polyacrylamide-based fluids, methods for inverting polyacrylamide emulsions

Abstract

The present application relates to the field of inverse polymer emulsion for shale oil and gas reservoir fracturing reconstruction, and discloses a surfactant, a preparation method and application thereof, an inverse polyacrylamide base liquid, and a phase inversion method of the inverse polyacrylamide emulsion.The structural formula of the surfactant is shown as formula I: formula (I); wherein R1 is a linear alkyl group with 6-17 carbon atoms; R2 and R3 are each independently an alkyl group with 1-3 carbon atoms; and R4 is a linear alkyl group with 8-20 carbon atoms.The surfactant has good hydrophilic and lipophilic properties, and when it is added to the inverse polyacrylamide emulsion together with the existing phase inversion agent, the inverse polyacrylamide emulsion after phase inversion can be quickly dissolved in water, the configuration efficiency of the fracturing fluid base liquid is improved, and the technical requirements of the fracturing fluid on site are met.

Description

Technical Field

[0001] This invention relates to the field of reverse polymer emulsions for fracturing and stimulation of shale oil and gas reservoirs, specifically to a surfactant and its preparation method and application, a reverse polyacrylamide-based liquid, and a phase inversion method for reverse polyacrylamide emulsions. Background Technology

[0002] With the development of oilfield development technology in my country, polyacrylamide has been widely used in drilling, fracturing, acidizing, water shut-off, cementing, and tertiary oil recovery, and the demand is enormous. Among them, polyacrylamide fracturing fluid, due to its characteristics of low resistance, good sand-carrying capacity, and ability to improve shale formation permeability, can effectively increase conductivity and reduce formation damage, making it the most widely used fracturing fluid system in large-scale volumetric fracturing technology.

[0003] Using powdered polyacrylamide products to prepare fracturing fluids in the field presents many problems, such as slow dissolution and a tendency to form fisheyes, especially when hydrophobic groups or other special groups are introduced, further worsening the solubility. During on-site operations, additives such as crosslinking agents, anti-swelling agents, flowback agents, breaker agents, and bactericides are also required, prolonging the preparation and application time. Reverse polyacrylamide emulsions, on the other hand, possess properties such as easy solubility, shear resistance, and high molecular chain strength, and exhibit good compatibility with various additives such as crosslinking agents, leading to their increasing application in fracturing processes. With the promulgation and implementation of national environmental protection laws, flowback fluids from fracturing processes require recycling, placing significant pressure on fracturing costs. Reverse polyacrylamide emulsion fracturing fluids exhibit good flocculation and sedimentation effects, and can be replenished in the flowback fluid before re-fracturing operations. Therefore, reverse polyacrylamide emulsion fracturing fluids can simplify the post-treatment of fracturing fluids.

[0004] Reverse polyacrylamide emulsions use an aqueous solution (acrylamide monomers) as the aqueous phase and a non-polar solvent as the oil phase. A surfactant disperses the aqueous phase into the oil phase, forming a W / O type emulsion. Water-soluble polyacrylamide is dispersed in an oil-in-water solution. If the reverse polyacrylamide emulsion is directly dissolved in water to prepare fracturing fluid, the emulsion conversion rate is slow, and lumps are easily formed. Adding a phase-inverting agent to the reverse emulsion can reduce the tension value of the oil-water interfacial film and decrease the interfacial elasticity, allowing the reverse polyacrylamide emulsion to dissolve rapidly in water. Currently available phase-inverting agents are polyoxyethylene ether-based. However, adding polyoxyethylene ether-based phase-inverting agents to the reverse polyacrylamide emulsion results in a slow dissolution rate in water, leading to a long preparation time for fracturing fluid. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned problems in the prior art and to provide a surfactant, its preparation method and application, a reverse polyacrylamide base liquid, and a phase inversion method for reverse polyacrylamide emulsions. This surfactant has good hydrophilic and lipophilic properties. When it is added together with existing polyoxyethylene ether phase inversion agents to reverse polyacrylamide emulsions, the two work synergistically to make the reverse polyacrylamide emulsions dissolve rapidly in water, thereby improving the efficiency of on-site fracturing fluid preparation.

[0006] To achieve the above objectives, the first aspect of the present invention provides a surfactant, the surfactant having the structural formula shown in Formula I: Formula (I); Wherein, R1 is a C6-C17 straight-chain alkyl group; R2 and R3 are each independently a C1-C3 alkyl group; and R4 is a C8-C20 straight-chain alkyl group.

[0007] A second aspect of the present invention provides a method for preparing the surfactant described in the first aspect, the method comprising: (1) In the presence of a first solvent, the compound shown in Formula 1 and the amine compound shown in Formula 2 are first mixed, and after a first reaction, solid-liquid separation is performed to obtain a first solid phase; (2) The first solid phase, alkaline solution and extractant obtained in step (1) are mixed and extracted, and the organic phase obtained by extraction is dried to obtain intermediate A; (3) In the presence of acid, intermediate A and the long-chain fatty acid shown in Formula 3 are mixed for the second time, followed by a second reaction and solid-liquid separation to obtain intermediate B. (4) In the presence of the second solvent, the sulfonating agent shown in Formula 4 is mixed with intermediate B for the third time, and after the third reaction, the solid and liquid phases are separated and the solid phase is washed to obtain the surfactant. Formula 1; where R1 is a C6-C17 straight-chain alkyl group and X is a halogen; Formula 2; wherein R2 and R3 are each independently a C1-C3 alkyl group; Equation 3; where R4 is C 8-20 Straight-chain alkyl groups; Equation 4; where R5 is H or Na.

[0008] A third aspect of the present invention provides a surfactant prepared by the preparation method described in the second aspect above.

[0009] A fourth aspect of the present invention provides the use of the surfactants described in the first and third aspects above in the phase inversion of reverse polyacrylamide emulsions.

[0010] The fifth aspect of the present invention provides a reverse polyacrylamide emulsion, the reverse polyacrylamide emulsion comprising: a reverse polyacrylamide emulsion, a surfactant as described in the first or third aspect above, a polyethylene ether phase inversion agent, and water.

[0011] The sixth aspect of this invention provides a method for phase inversion of a reverse polyacrylamide emulsion, the method comprising: (a) The surfactant and polyoxyethylene ether phase inversion agent described in the first or third aspect above are added to the reverse polyacrylamide emulsion and mixed thoroughly to obtain a stable phase inversion emulsion; (b) Dissolve the phase inversion emulsion from step (a) in water and stir to obtain a reversed polyacrylamide base liquid.

[0012] Through the above technical solutions, the surfactant, its preparation method and application, reverse polyacrylamide-based liquid, and phase inversion method of reverse polyacrylamide emulsion provided by the present invention achieve the following beneficial effects: This invention provides a novel surfactant. The long-chain alkyl group increases the contact area with the oil phase and expands the swept volume of the oil phase, while the sulfonic acid group and hydroxyl group have strong hydrophilicity. Therefore, when it is added to the reverse polyacrylamide emulsion in combination with existing phase inversion agents, the long-chain alkyl part of the surfactant is rapidly dispersed into the reverse emulsion, carrying the polyoxyethylene ether phase inversion agent to quickly penetrate to the water-in-oil interface. The polyoxyethylene ether has excellent emulsification and penetration functions. The two work synergistically to greatly reduce the elasticity and tension value of the oil-water interface, so that the reverse polyacrylamide emulsion after phase inversion can be rapidly dissolved in water. This can significantly improve the rapid dissolution capacity of the reverse polyacrylamide emulsion in the field, improve the efficiency of fracturing fluid base fluid preparation, and meet the technical requirements of fracturing fluid in the field. Attached Figure Description

[0013] Figure 1 This is the infrared spectrum of the surfactant prepared in Example 2. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] The first aspect of this invention provides a surfactant, the surfactant having the structural formula shown in Formula I: Formula (I); Wherein, R1 is a C6-C17 straight-chain alkyl group; R2 and R3 are each independently a C1-C3 alkyl group; and R4 is a C8-C20 straight-chain alkyl group.

[0016] The surfactant described in this invention possesses strong hydrophilic and lipophilic properties. Due to the introduction of long-chain aliphatic hydrocarbons and long-chain alkyl groups provided by the compound shown in Formula 1 into its molecular structure, the long-chain alkyl groups can increase the contact area with the oil phase, expanding the swept volume with the oil phase. Furthermore, the sulfonic acid groups and hydroxyl groups have strong hydrophilicity, further enhancing the hydrophilic and lipophilic properties of the surfactant.

[0017] According to the present invention, preferably, R1 is a C11-C16 straight-chain alkyl group, R2 and R3 are each independently a C1-C2 alkyl group, and R4 is a C12-C18 straight-chain alkyl group.

[0018] According to the present invention, preferably, the hydrophilic-lipophilic balance (HLB) value of the surfactant is 10.5-12.9, indicating that the surfactant of the present invention has good hydrophilic-lipophilic properties.

[0019] In this invention, the hydrophilic-lipophilic balance (HLB) value of the surfactant is determined using the test tube method.

[0020] A second aspect of the present invention provides a method for preparing the surfactant described in the first aspect, the method comprising: (1) In the presence of a first solvent, the compound shown in Formula 1 and the amine compound shown in Formula 2 are first mixed, and after a first reaction, solid-liquid separation is performed to obtain a first solid phase; (2) The first solid phase, alkaline solution and extractant obtained in step (1) are mixed and extracted, and the extracted phase is dried to obtain intermediate A; (3) In the presence of acid, intermediate A and the long-chain fatty acid shown in Formula 3 are mixed for the second time, followed by a second reaction and solid-liquid separation to obtain intermediate B. (4) In the presence of the second solvent, the sulfonating agent shown in Formula 4 is mixed with intermediate B for the third time, and after the third reaction, the solid and liquid phases are separated and the solid phase is washed to obtain the surfactant. Formula 1; where R1 is a C6-C17 straight-chain alkyl group and X is a halogen; Formula 2, wherein R2 and R3 are each independently a C1-C3 alkyl group; Formula 3; where R4 is a C8-C20 straight-chain alkyl group.

[0021] Equation 4; where R5 is H or Na.

[0022] In this invention, the preparation method of the surfactant is simple and easy to operate. Using a compound containing the long-chain alkyl group shown in Formula 1 can increase the contact area with the oil phase and expand the sweep volume with the oil phase. Furthermore, the long-chain fatty acid shown in Formula 3 provides more long-chain alkyl groups, which further increases the lipophilic properties. Finally, the sulfonic acid group and hydroxyl group provided by the sulfonating agent have strong hydrophilicity, so that the final surfactant has good hydrophilic and lipophilic properties.

[0023] More preferably, in the compound shown in Formula 1, R1 is a C11-C16 straight-chain alkyl group; X is Cl and / or Br.

[0024] According to the present invention, preferably, the amine compound represented by Formula 2 is one or more of dimethylamine, diethylamine and dipropylamine, preferably dimethylamine; using the aforementioned preferred amine compound is beneficial for the reaction to proceed.

[0025] In this invention, the compounds shown in Formula 1 and the amine compounds shown in Formula 2 are both commercially available.

[0026] In this invention, there are no particular limitations on the first mixing method of the compound shown in Formula 1 and the amine compound shown in Formula 2. For example, the compound shown in Formula 1 can be mixed and dissolved in a first solvent first, and then the amine compound shown in Formula 2 can be added.

[0027] In this invention, there are no particular limitations on the temperature and time of the first mixing. Preferably, the first mixing is carried out at room temperature, and the mixing time is adjusted accordingly based on the actual situation.

[0028] According to the present invention, preferably, the mass ratio of the compound represented by Formula 1 and the amine compound represented by Formula 2 is 1:1.5-3, for example, it can be 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3 or any range formed by any two of the above values ​​and values ​​within that range.

[0029] In this invention, when the mass ratio of the compound shown in Formula 1 to the amine compound shown in Formula 2 meets the above-mentioned range, it is beneficial to the formation of the first solid phase.

[0030] More preferably, the mass ratio of the compound shown in Formula 1 to the amine compound shown in Formula 2 is 1:2-2.5.

[0031] In this invention, there is no particular limitation on the type of the first solvent in step (1), as long as the compound shown in Formula 1 and the amine compound shown in Formula 2 are fully mixed and dissolved. Preferably, the first solvent is anhydrous ethanol.

[0032] In this invention, there is no particular limitation on the amount of solvent used, as long as the compound shown in Formula 1 and the amine compound shown in Formula 2 are fully mixed and dissolved. Preferably, the mass concentration of the compound shown in Formula 1 and the amine compound shown in Formula 2 in the first mixed solution is 15-22 wt%, which can be any two values ​​within the range of 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, or more, and more preferably 16-20 wt%.

[0033] In this invention, the first reaction is preferably carried out by reflux.

[0034] In this invention, there are no particular limitations on the temperature and time of the first reaction. Preferably, the temperature of the first reaction is 60-90℃, which can be any two values ​​of 60℃, 65℃, 70℃, 75℃, 80℃, 83℃, 85℃, 90℃ or above, or values ​​within that range. Preferably, the time of the first reaction is 6-12h, which can be any two values ​​of 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, 12h or above, or values ​​within that range.

[0035] In this invention, the solid-liquid separation is a conventional operation in the art. Preferably, the solid-liquid separation operation temperature is 60-65℃. A vacuum rotary evaporator is used to remove the solvent to obtain the solid phase. Further details will not be elaborated below.

[0036] In this invention, there is no particular limitation on the type of alkali in step (2). Preferably, the alkali solution is one or more of sodium bicarbonate solution, sodium carbonate and potassium carbonate, and more preferably sodium bicarbonate solution.

[0037] In this invention, there is no particular limitation on the type of solvent for the alkaline solution, but water is preferred as the solvent.

[0038] In this invention, there are no particular limitations on the concentration and amount of the alkaline solution, as long as it can remove the unreacted raw materials in the first solid phase. Preferably, the mass ratio of the first solid phase to the alkaline solution is 1:15-25.

[0039] In this invention, there are no particular limitations on the extraction temperature and time; conventional choices in the field can be made, such as extraction at room temperature with the extraction time adjusted accordingly based on the actual situation.

[0040] In this invention, there is no particular limitation on the type of extractant, as long as the first solid phase can be fully extracted. Preferably, the extractant is one or more of chloroform, dichloromethane and acetone, and more preferably chloroform.

[0041] In this invention, there is no particular limitation on the amount of the extractant used, and it can be a conventional choice in the art.

[0042] In this invention, preferably, the drying is a conventional operation in the art, which can remove residual chloroform in the organic phase, and preferably vacuum drying.

[0043] In this invention, there are no particular limitations on the vacuum drying temperature and time, and conventional choices in the field can be made. Preferably, the vacuum drying temperature is 3-25°C and the time is 4-10 hours.

[0044] According to the present invention, preferably, the R4 of the long-chain fatty acid represented by formula 3 in step (3) is a straight-chain alkyl group of C12-C18, more preferably one or more of lauric acid, myristic acid and stearic acid.

[0045] In this invention, the long-chain fatty acid represented by Formula 3 can be purchased commercially.

[0046] According to the present invention, preferably, the mass ratio of intermediate A and the long-chain fatty acid represented by Formula 3 is 1:1.5-3.5, which can be 1:1.5, 1:1.7, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.5 or any two of the above values ​​within a range.

[0047] In this invention, when the mass ratio of intermediate A and the long-chain fatty acid shown in Formula 3 meets the above-mentioned range, it is beneficial to generate intermediate B.

[0048] More preferably, the mass ratio of intermediate A and the long-chain fatty acid shown in Formula 3 is 1:2-3.2; In this invention, there is no particular limitation on the type of acid, as long as intermediate A and the long-chain fatty acid shown in Formula 3 react fully. Preferably, the acid is one or more of concentrated sulfuric acid, concentrated hydrochloric acid, p-toluenesulfonic acid, phosphoric acid, boric acid, sulfonic acid and toluenesulfonic acid.

[0049] In this invention, the amount of acid used is preferably 1-3% of the mass of intermediate A.

[0050] In this invention, there is no particular limitation on the concentration of the acid; it can be a conventional choice in the art, as long as the second reaction proceeds sufficiently.

[0051] In this invention, there are no particular limitations on the temperature and time of the second mixing. It is preferred that the second mixing is carried out at room temperature, and the mixing time is adjusted according to the actual situation.

[0052] In this invention, the second reaction is carried out by stirring, preferably at a stirring speed of 200-500 rpm.

[0053] In this invention, the second reaction is preferably carried out by reflux.

[0054] According to the present invention, preferably, there are no particular limitations on the temperature and time of the second reaction, but preferably the temperature of the second reaction is 60-90°C and the time is 3-8h.

[0055] In this invention, the sulfonating agent shown in Formula 4 provides sulfonic acid groups, which is more conducive to improving the hydrophilicity of the surfactant. Preferably, the sulfonating agent shown in Formula 4 is sodium 3-chloro-2-hydroxypropanesulfonate and / or 3-chloro-2-hydroxypropanesulfonic acid, and more preferably sodium 3-chloro-2-hydroxypropanesulfonate.

[0056] According to the present invention, preferably, the mass ratio of the sulfonating agent and intermediate B shown in Formula 4 is 1-3:1, which can be 1:1, 1.5:1, 1.8:1, 2:1, 2.3:1, 2.5:1, 3:1 or any two of the above values ​​within a range or value within that range.

[0057] In this invention, when the mass ratio of the sulfonating agent and intermediate B shown in Formula 4 meets the above-mentioned range, it is beneficial to the formation of surfactant.

[0058] More preferably, the mass ratio of the sulfonating agent and intermediate B shown in Formula 4 is 1.2-2.2:1; According to the present invention, preferably, the mass concentration of the sulfonating agent and intermediate B shown in Formula 4 in the third mixed solution is 15-20 wt%, more preferably 16-18 wt%.

[0059] In this invention, there are no particular limitations on the temperature and time of the third mixing. It is preferred that the third mixing is carried out at room temperature, and the mixing time is adjusted according to the actual situation.

[0060] In this invention, the third reaction is carried out under stirring conditions, preferably at a stirring speed of 200-500 rpm.

[0061] In this invention, the third reaction is preferably carried out by reflux.

[0062] In this invention, there are no particular limitations on the temperature and time of the third reaction. Preferably, the temperature of the third reaction is 70-90°C and the time is 5-10 hours.

[0063] In this invention, step (4) further includes washing the product after solid-liquid separation. Preferably, ethyl acetate is used to wash the crude product, and the product is dried at room temperature to obtain the final surfactant.

[0064] A third aspect of the present invention provides a surfactant prepared by the preparation method described in the second aspect above.

[0065] A fourth aspect of the present invention provides the use of the surfactants described in the first and third aspects above in the phase inversion of reverse polyacrylamide emulsions.

[0066] The fifth aspect of the present invention provides a reverse polyacrylamide-based liquid, the reverse polyacrylamide-based liquid comprising: a reverse polyacrylamide emulsion, a surfactant as described in the first or third aspect above, a polyethylene ether phase inversion agent, and water.

[0067] The sixth aspect of this invention provides a method for phase inversion of a reverse polyacrylamide emulsion, the method comprising: (a) The surfactant and polyoxyethylene ether phase inversion agent described in the first or third aspect above are added to the reverse polyacrylamide emulsion and mixed thoroughly to obtain a stable phase inversion emulsion; (b) Dissolve the phase inversion emulsion from step (a) in water and stir to obtain a reversed polyacrylamide base liquid.

[0068] According to the present invention, preferably, the polyoxyethylene ether phase inversion agent in step (a) is one or more of alkylphenol polyoxyethylene ethers, fatty alcohol polyoxyethylene ethers and fatty acid polyoxyethylene esters, preferably alkylphenol polyoxyethylene ethers and fatty alcohol polyoxyethylene ethers.

[0069] In this invention, the reverse polyacrylamide emulsion can be a reverse polyacrylamide emulsion conventionally used in the art, such as BM reverse polyacrylamide emulsion or BH reverse polyacrylamide emulsion, which can be prepared by commercially available products or conventional techniques in the art.

[0070] According to the present invention, preferably, the mass concentration of the surfactant and the polyoxyethylene ether phase inversion agent in the stable phase inversion emulsion is 1-8 wt%, and can be any two values ​​within the range of 1 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, or more, preferably 2.5-6 wt%. According to the present invention, preferably, the mass ratio of the surfactant and the polyoxyethylene ether phase-transfer agent is 1:20-99, which can be 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:85, 1:90, 1:95, 1:99 or any two of the above values ​​within a range. Using the aforementioned preferred mass ratio is beneficial for the two substances to dissolve more uniformly in the reacting polyacrylamide emulsion, and more preferably 1:40-95.

[0071] In this invention, step (a) is carried out under stirring conditions, preferably at a stirring speed of 400-600 rpm.

[0072] In this invention, there are no particular limitations on the mixing temperature and time of step (a). Preferably, the mixing temperature of step (a) is 30-40°C and the time is 1.5-1h.

[0073] According to the present invention, preferably, the mass ratio of phase inversion emulsion to water in step (b) is 0.0008-0.008:1, more preferably 0.001-0.006:1.

[0074] The present invention will be described in detail below through embodiments.

[0075] Unless otherwise specified, all reagents used in the following examples are commercially available.

[0076] Vacuum rotary evaporator, model RE300, manufactured by Stuart, UK.

[0077] In this invention, the structural composition of the surfactant S is determined using infrared spectroscopy. Example 1 (1) Dissolve 10.6g of 16-bromo-hexadecyl alcohol in 200g of anhydrous ethanol, add 21.4g of dimethylamine solution, reflux at 60℃ for 12h, and then remove the anhydrous ethanol by vacuum rotary evaporation in a water bath at 60℃ to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:15 and the concentration of sodium bicarbonate solution was 8wt%). The extracted organic phase was placed in a vacuum drying oven and dried for 4 hours (the temperature of the vacuum drying oven was 25℃) to obtain intermediate A1 with a mass of 10.87g. (3) In the presence of sulfuric acid, 16g of lauric acid and 8g of intermediate A1 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 60°C and 500rpm for 3h. Afterward, solid-liquid separation was performed at 60°C using a vacuum rotary evaporator to obtain intermediate B1 with a mass of 11.61g. (4) In the presence of 100g isopropanol, 8.73g of sodium 3-chloro-2-hydroxypropanesulfonate and 7.27g of intermediate B1 were added and mixed. The mixture was reacted at 70℃ and 500rpm for 10h. Then, solid-liquid separation was performed at 60℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant S1 with a mass of 7.48g.

[0078] The hydrophilic-lipophilic balance (HLB) of S1 is 10.8.

[0079] Example 2 (1) Dissolve 11.24 g of 15-bromo-pentadecanol in 200 g of anhydrous ethanol, add 24.76 g of dimethylamine solution, reflux at 80 °C for 8 h, and then remove the anhydrous ethanol by vacuum rotary evaporation in a water bath at 60 °C to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:20, and the concentration of sodium bicarbonate solution was 8wt%). The extracted organic phase was placed in a vacuum drying oven and dried for 6 hours (the temperature of the vacuum drying oven was 18℃) to obtain intermediate A2 with a mass of 11.5g. (3) In the presence of sulfuric acid, 20g of myristic acid and 8g of intermediate A2 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 80°C and 400rpm for 5h. After that, solid-liquid separation was performed by vacuum rotary evaporator at 62°C to obtain intermediate B2 with a mass of 12.43g. (4) In the presence of 100g isopropanol, 11.34g of sodium 3-chloro-2-hydroxypropanesulfonate and 5.66g of intermediate B2 were added and mixed. The mixture was reacted at 80℃ and 400rpm for 8h. Then, solid-liquid separation was performed at 62℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant S2 with a mass of 5.82g.

[0080] The hydrophilic-lipophilic balance (HLB) of S2 is 12.2. The infrared spectrum of S2 is shown below. Figure 1 The above, Figure 1 Middle, 1740cm -1The peak represents the stretching vibration of the C=O ester group, proving that intermediate B was successfully synthesized from Equation 3 and intermediate A. (1468 cm⁻¹) -1 The absorption peaks are in-plane rocking vibrations of CH3- and CH2-, confirming the presence of long-chain alkyl groups in formulas 1 and 4. (1206 cm⁻¹) -1 It is CH2-SO3 - Asymmetric stretching vibration absorption peak, 1042 cm⁻¹ -1 It is the σ of amines C-N The in-plane bending vibration absorption peak confirms the presence of the quaternary ammonium group, and formulas 1, 2, and 4 have been successfully synthesized. (618 cm⁻¹) -1 and 528cm -1 It is -SO3 - The strong absorption peak indicates the presence of sulfonic acid groups.

[0081] Example 3 (1) Dissolve 11.42 g of 11-bromo-undecaneol in 200 g of anhydrous ethanol, add 28.58 g of dimethylamine solution, reflux at 90 °C for 6 h, and then remove the anhydrous ethanol by vacuum rotary evaporation in a water bath at 60 °C to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:25 and the concentration of sodium bicarbonate solution was 8wt%). The extracted organic phase was placed in a vacuum drying oven and dried for 10h (the temperature of the vacuum drying oven was 20℃) to obtain intermediate A3 with a mass of 11.96g. (3) In the presence of sulfuric acid, 24g of stearic acid and 8g of intermediate A3 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 90°C and 200rpm for 8 hours. Afterward, solid-liquid separation was performed by vacuum rotary evaporator at 65°C to obtain intermediate B3 with a mass of 14.97g. (4) In the presence of 100g isopropanol, 12.38g of sodium 3-chloro-2-hydroxypropanesulfonate and 5.62g of intermediate B3 were added and mixed. The mixture was reacted at 90℃ and 200rpm for 5h. Then, solid-liquid separation was performed at 65℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant S3 with a mass of 5.78g.

[0082] The hydrophilic-lipophilic balance (HLB) of S3 is 12.3.

[0083] Example 4 (1) Dissolve 12g of 16-bromo-hexadecyl alcohol in 200g of anhydrous ethanol, add 18g of dimethylamine solution, reflux at 60℃ for 12h, and then remove the anhydrous ethanol by vacuum rotary evaporation under a water bath at 60℃ to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:17 and the concentration of sodium bicarbonate solution was 8wt%). The extracted organic phase was placed in a vacuum drying oven and dried for 7 hours (the temperature of the vacuum drying oven was 15℃) to obtain intermediate A4 with a mass of 12.31g. (3) In the presence of sulfuric acid, 12g of myristic acid and 8g of intermediate A4 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 70°C and 300rpm for 5h. Afterward, solid-liquid separation was performed by vacuum rotary evaporator at 60°C to obtain intermediate B4 with a mass of 12.23g. (4) In the presence of 100g isopropanol, 7.5g of sodium 3-chloro-2-hydroxypropanesulfonate and 7.5g of intermediate B4 were added and mixed. The mixture was reacted at 70℃ and 500rpm for 10h. Then, solid-liquid separation was performed at 60℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant S4 with a mass of 7.72g.

[0084] The hydrophilic-lipophilic balance (HLB) of S4 is 12.9.

[0085] Example 5 (1) Dissolve 11.06 g of 16-bromo-hexadecyl alcohol in 200 g of anhydrous ethanol, add 19.94 g of dimethylamine solution, reflux at 60 °C for 12 h, and then remove the anhydrous ethanol by vacuum rotary evaporation under a water bath at 60 °C to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:19 and the concentration of sodium bicarbonate solution was 8wt%). The extracted organic phase was placed in a vacuum drying oven and dried for 7h (the temperature of the vacuum drying oven was 15℃) to obtain intermediate A5 with a mass of 11.35g. (3) In the presence of sulfuric acid, 14.4 g of lauric acid and 8 g of intermediate A5 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 70 °C and 300 rpm for 6 h. Afterward, solid-liquid separation was performed by vacuum rotary evaporator at 60 °C to obtain intermediate B5 with a mass of 11.61 g. (4) In the presence of 100g isopropanol, 8.51g of sodium 3-chloro-2-hydroxypropanesulfonate and 7.09g of intermediate B5 were added and mixed. The mixture was reacted at 70℃ and 500rpm for 10h. Then, solid-liquid separation was performed at 60℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant S5 with a mass of 7.30g.

[0086] The hydrophilic-lipophilic balance (HLB) of S5 is 10.9.

[0087] Example 6 (1) Dissolve 12g of 16-bromo-pentadecanol in 200g of anhydrous ethanol, add 30g of dimethylamine solution, reflux at 70℃ for 10h, and then remove the anhydrous ethanol by vacuum rotary evaporation under a water bath at 60℃ to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:23 and the concentration of sodium bicarbonate solution was 8wt%). The organic phase obtained by extraction was placed in a vacuum drying oven and dried for 7h (the temperature of the vacuum drying oven was 15℃) to obtain intermediate A6 with a mass of 12.34g. (3) In the presence of hydrochloric acid, 25.6 g of lauric acid and 8 g of intermediate A6 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 60 °C and 500 rpm for 6 h. Afterward, solid-liquid separation was performed at 62 °C using a vacuum rotary evaporator to obtain intermediate B6 with a mass of 11.78 g. (4) In the presence of 100g isopropanol, 13.58g of sodium 3-chloro-2-hydroxypropanesulfonate and 5.42g of intermediate B6 were added and mixed. The mixture was reacted at 80℃ and 400rpm for 8h. Then, solid-liquid separation was performed at 62℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant S6 with a mass of 5.58g.

[0088] The hydrophilic-lipophilic balance (HLB) of S6 is 10.5.

[0089] Example 7 (1) Dissolve 11g of 16-bromo-pentadecanol in 200g of anhydrous ethanol, add 33g of dimethylamine solution, reflux at 70℃ for 10h, and then remove the anhydrous ethanol by vacuum rotary evaporation under a water bath at 60℃ to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:23 and the concentration of sodium bicarbonate solution was 8wt%). The organic phase obtained by extraction was placed in a vacuum drying oven and dried for 6 hours (the temperature of the vacuum drying oven was 18℃) to obtain intermediate A7 with a mass of 11.30g. (3) In the presence of hydrochloric acid, 28g of myristic acid and 8g of intermediate A7 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 60°C and 500rpm for 8 hours. Then, solid-liquid separation was performed at 62°C using a vacuum rotary evaporator to obtain intermediate B7 with a mass of 12.43g. (4) In the presence of 100g isopropanol, 15g of sodium 3-chloro-2-hydroxypropanesulfonate and 5g of intermediate B7 were added and mixed. The mixture was reacted at 80℃ and 400rpm for 8h. Then, solid-liquid separation was performed at 62℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant S7 with a mass of 5.15g.

[0090] The hydrophilic-lipophilic balance (HLB) of S7 is 12.1.

[0091] Comparative Example 1 (1) Dissolve 11.24 g of 2-bromoethanol in 200 g of anhydrous ethanol, add 24.76 g of dimethylamine solution, reflux at 80 °C for 8 h, and then remove the anhydrous ethanol by vacuum rotary evaporation in a water bath at 60 °C to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:20 and the concentration of sodium bicarbonate solution was 8wt%). The organic phase obtained by extraction was placed in a vacuum drying oven and dried for 6 hours (the temperature of the vacuum drying oven was 18℃) to obtain intermediate AD1 with a mass of 12.76g. (3) In the presence of sulfuric acid, 20g of myristic acid and 8g of intermediate AD1 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 80°C and 400rpm for 5h. Afterward, solid-liquid separation was performed by vacuum rotary evaporator at 62°C to obtain intermediate BD1 with a mass of 18.38g. (4) In the presence of 100g isopropanol, 11.34g of sodium 3-chloro-2-hydroxypropanesulfonate and 5.66g of intermediate BD1 were added and mixed. The mixture was reacted at 80℃ and 400rpm for 8h. Then, solid-liquid separation was performed at 62℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant DS1 with a mass of 5.86g.

[0092] The hydrophilic-lipophilic balance (HLB) of DS1 is 12.4.

[0093] Comparative Example 2 (1) Dissolve 11.24 g of 15-bromo-pentadecanol in 200 g of anhydrous ethanol, add 24.76 g of dimethylamine solution, reflux at 80 °C for 8 h, and then remove the anhydrous ethanol by vacuum rotary evaporation in a water bath at 60 °C to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:20 and the concentration of sodium bicarbonate solution was 8wt%). The organic phase obtained by extraction was placed in a vacuum drying oven and dried for 6 hours (the temperature of the vacuum drying oven was 18℃) to obtain intermediate AD2 with a mass of 11.5g. (3) In the presence of sulfuric acid, 20g of acetic acid and 8g of intermediate AD2 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 80°C and 400rpm for 5h. Afterward, solid-liquid separation was performed by vacuum rotary evaporator at 62°C to obtain intermediate BD2 with a mass of 8.56g. (4) In the presence of 100g isopropanol, 11.34g of sodium 3-chloro-2-hydroxypropanesulfonate and 5.66g of intermediate BD2 were added and mixed. The mixture was reacted at 80℃ and 400rpm for 8h. Then, solid-liquid separation was performed at 62℃ using a vacuum rotary evaporator to remove isopropanol. The crude product was washed with ethyl acetate to finally obtain surfactant DS2 with a mass of 5.32g.

[0094] The hydrophilic-lipophilic balance (HLB) of DS1 is 12.6.

[0095] Comparative Example 3 (1) Dissolve 11.24 g of 15-bromo-pentadecanol in 200 g of anhydrous ethanol, add 24.76 g of dimethylamine solution, reflux at 80 °C for 8 h, and then remove the anhydrous ethanol by vacuum rotary evaporation in a water bath at 60 °C to obtain the first solid phase. (2) The first solid phase obtained in step (1), sodium bicarbonate solution, and chloroform were mixed and extracted (the amount of the first solid phase and the amount of sodium bicarbonate solution were such that the mass ratio of the two was 1:20 and the concentration of sodium bicarbonate solution was 8wt%). The organic phase obtained by extraction was placed in a vacuum drying oven and dried for 6 hours (the temperature of the vacuum drying oven was 18℃) to obtain intermediate AD3 with a mass of 11.5g. (3) In the presence of sulfuric acid, 20g of myristic acid and 8g of intermediate AD3 prepared in step (2) were added to a three-necked flask and mixed. The mixture was heated under reflux at 80°C and 400rpm for 5h. Afterward, solid-liquid separation was performed by vacuum rotary evaporator at 62°C to obtain intermediate BD3 with a mass of 12.43g. (4) In the presence of 100g isopropanol, 5.66g of intermediate BD3 was added and mixed, and the mixture was reacted at 80℃ and 400rpm for 8h. Then, solid-liquid separation was performed at 62℃ using a vacuum rotary evaporator to remove isopropanol, and the crude product was washed with ethyl acetate to finally obtain surfactant DS3 with a mass of 5.59g.

[0096] The hydrophilic-lipophilic balance (HLB) of DS3 is 10.6.

[0097] Test case Raw material: OP-10, purchased from Shandong Jubang Chemical Co., Ltd.; BM reversed polyacrylamide emulsion was purchased from Shandong Baomo Biochemical Co., Ltd. BH reverse polyacrylamide emulsion, prepared according to patent CN104974737B.

[0098] The surfactant, reverse polyacrylamide emulsion, polyethylene ether phase-inverting agent, and water prepared in the examples were respectively formulated into reverse polyacrylamide-based solutions according to the following methods: (a) 0.06 g of surfactant and 2.94 g of OP-10 phase inversion agent were added to 50 g of BM and BH reverse polyacrylamide emulsions, respectively. Stable phase inversion emulsions were obtained by stirring at 400 rpm for 0.5 h at 30 °C. (b) Weigh 0.5g of the phase inversion emulsion into 100g of water and stir at 400rpm to obtain reverse polyacrylamide base liquids C1-C7.

[0099] Comparative test cases 1-3 The method is the same as in the test example, except that in step (a), the surfactant prepared in the comparative example is added to obtain reverse polyacrylamide-based liquids CD1-CD3.

[0100] Comparative Test Example 4 The method is the same as in the test example, except that in step (a), no surfactant is added, but only 3g of OP-10 is added to obtain the reverse polyacrylamide base liquid CD4.

[0101] Comparative Test Example 5 The method in the test example is different except that in step (a), only 3g of surfactant is added and OP-10 is not added to obtain the reverse polyacrylamide base liquid CD5.

[0102] The 40s viscosity release rates of the BM and BH reverse polyacrylamide-based liquids prepared in the test examples and comparative test examples are shown in Table 1: Table 1

[0103] Note: The phase inversion emulsion is dissolved in water and stirred continuously to obtain a reverse polyacrylamide base liquid. The base liquid is taken out after stirring for 40s and 2h respectively and its viscosity is tested at room temperature. The ratio of the viscosity of the base liquid at 40s to the viscosity of the base liquid at 2h is the viscosity release rate at 40s.

[0104] As can be seen from the data in Table 1, when the surfactants prepared in Examples 1-7 were used to prepare reverse polyacrylamide-based liquids, the BM sample had the highest viscosity release rate of 96.1% in 40s, and the BH sample had the highest viscosity release rate of 86.1% in 40s.

[0105] In Comparative Test Example 1, since 15-bromo-pentadecanol was replaced with 2-bromoethanol, the long-chain alkyl part of the prepared surfactant only has the long-chain alkyl part of the long-chain fatty acid, which makes its diffusion rate in the reverse emulsion slow and unable to carry the polyoxyethylene ether phase inversion agent to quickly penetrate to the oil-water interface. As a result, the dissolution rate of the reverse emulsion in water is reduced, which leads to a significant reduction in the 40s viscosity release rate.

[0106] In Comparative Test Example 2, since the long-chain fatty acid was replaced with acetic acid, the long-chain alkyl part of the prepared surfactant only has the long-chain alkyl part of compound A shown in Formula 1. When the surfactant is added to the reverse polyacrylamide emulsion, it cannot carry the polyoxyethylene ether to the oil-water interface quickly, and cannot reduce the interfacial tension value. The dissolution rate of the reverse emulsion in water is slowed down, resulting in a significant decrease in the viscosity release rate at 40s.

[0107] In comparative test example 3, the lack of hydrophilic sulfonic acid groups in the surfactant synthesized in comparative example 3 resulted in a slower dissolution rate of the reverse emulsion in water and a significant decrease in the viscosity release rate at 40s.

[0108] In comparative test example 4, only OP-10 was added. The viscosity release rate of the prepared reverse polyacrylamide-based liquid was lower than that of examples 1-7. This is because OP-10 dissolves slowly in the reverse emulsion and cannot quickly reach the oil-water interface. As a result, the reverse emulsion dissolves slowly in water, and the viscosity release rate in 40s is also very low.

[0109] In comparative test example 5, only surfactant was added, and the viscosity release rate in 40 seconds was lower than that in examples 1-7. The surface activity could not quickly reduce the oil-water interfacial tension, resulting in a very low viscosity release rate.

[0110] Therefore, the synergistic effect of the surfactant and polyoxyethylene ether phase inversion agent described in this invention can reduce the oil-water interfacial tension in the reverse emulsion and ultimately increase the dissolution rate of the reverse emulsion in water.

[0111] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A surfactant, characterized in that, The structural formula of the surfactant is shown in Formula I: Equation (I); Wherein, R1 is a C6-C17 straight-chain alkyl group; R2 and R3 are each independently a C1-C3 alkyl group; and R4 is a C8-C20 straight-chain alkyl group.

2. The surfactant according to claim 1, wherein, R1 is a C11-C16 straight-chain alkyl group; R2 and R3 are each independently a C1-C2 alkyl group; R4 is a C12-C18 straight-chain alkyl group. Preferably, the hydrophilic-lipophilic balance (HLB) of the surfactant is 10.5-12.

9.

3. A method for preparing a surfactant, characterized in that, The method includes: (1) In the presence of a first solvent, the compound shown in Formula 1 and the amine compound shown in Formula 2 are first mixed, and after a first reaction, solid-liquid separation is performed to obtain a first solid phase; (2) The first solid phase, alkaline solution and extractant obtained in step (1) are mixed and extracted, and the organic phase obtained by extraction is dried to obtain intermediate A; (3) In the presence of acid, intermediate A and the long-chain fatty acid shown in Formula 3 are mixed for the second time, followed by a second reaction and solid-liquid separation to obtain intermediate B. (4) In the presence of the second solvent, the sulfonating agent shown in Formula 4 is mixed with intermediate B for the third time, and after the third reaction, the solid and liquid phases are separated and the solid phase is washed to obtain the surfactant. Formula 1; where R1 is a C6-C17 straight-chain alkyl group and X is a halogen; Formula 2, wherein R2 and R3 are each independently a C1-C3 alkyl group; Formula 3; wherein R4 is a C8-C20 straight-chain alkyl group; Equation 4; where R5 is H or Na.

4. The preparation method according to claim 3, wherein, R1 is a C11-C16 straight-chain alkyl group; X is Cl and / or Br; Preferably, the amine compound represented by Formula 2 is one or more of dimethylamine, diethylamine, and dipropylamine, and is preferably dimethylamine; Preferably, the mass ratio of the compound represented by Formula 1 to the amine compound represented by Formula 2 is 1:1.5-3, more preferably 1:2-2.5; Preferably, the mass concentration of the compound represented by Formula 1 and the amine compound represented by Formula 2 in the first mixed solution is 15-22 wt%, more preferably 16-20 wt%. Preferably, the conditions for the first reaction include: a temperature of 60-90°C and a time of 6-12 hours.

5. The preparation method according to claim 3, wherein, The alkaline solution in step (2) is one or more of sodium bicarbonate solution, sodium carbonate solution and potassium carbonate solution, preferably sodium bicarbonate solution; Preferably, the extractant is one or more of chloroform, dichloromethane, and acetone, with chloroform being the most preferred; Preferably, the mass ratio of the first solid phase to the alkaline solution is 1:15-25.

6. The preparation method according to claim 3, wherein, R4 is a C12-C18 straight-chain alkyl group, preferably one or more of lauric acid, myristic acid and stearic acid; Preferably, the mass ratio of intermediate A and the long-chain fatty acid shown in Formula 3 is 1:1.5-3.5, more preferably 1:2-3.2; Preferably, the acid is one or more selected from concentrated sulfuric acid, concentrated hydrochloric acid, p-toluenesulfonic acid, phosphoric acid, boric acid, sulfonic acid, and toluenesulfonic acid; Preferably, the conditions for the second reaction include: a temperature of 60-90°C and a time of 3-8 hours.

7. The preparation method according to claim 3, wherein, The sulfonating agent shown in Formula 4 is sodium 3-chloro-2-hydroxypropanesulfonate and / or 3-chloro-2-hydroxypropanesulfonic acid, preferably sodium 3-chloro-2-hydroxypropanesulfonate. Preferably, the mass ratio of the sulfonating agent and intermediate B shown in Formula 4 is 1-3:1, more preferably 1.2-2.2:1; Preferably, the mass concentration of the sulfonating agent and intermediate B shown in Formula 4 in the third mixed solution is 15-20 wt%, more preferably 16-18 wt%. Preferably, the third reaction conditions include: a temperature of 70-90°C and a time of 5-10 hours.

8. A surfactant prepared by any one of claims 3-7.

9. The use of the surfactant according to claims 1-2 or 8 in the phase inversion of reverse polyacrylamide emulsions.

10. A reverse polyacrylamide-based liquid, characterized in that, The reverse polyacrylamide base liquid comprises: reverse polyacrylamide emulsion, surfactant as described in claims 1-2 or 8, polyethylene ether phase inversion agent, and water.

11. A method for phase inversion of a reverse polyacrylamide emulsion, characterized in that, The phase-inversion method includes: (a) The surfactant and polyoxyethylene ether phase inversion agent described in claims 1-2 or 8 are added to the reverse polyacrylamide emulsion and mixed thoroughly to obtain a stable phase inversion emulsion; (b) Dissolve the phase inversion emulsion from step (a) in water and stir to obtain a reversed polyacrylamide base liquid.

12. The phase inversion method according to claim 11, wherein, In step (a), the polyoxyethylene ether phase inversion agent is one or more of alkylphenol polyoxyethylene ethers, fatty alcohol polyoxyethylene ethers, and fatty acid polyoxyethylene esters, preferably alkylphenol polyoxyethylene ethers or fatty alcohol polyoxyethylene ethers. Preferably, the mass concentration of surfactant and polyoxyethylene ether phase inversion agent in the stable phase inversion emulsion is 1-8 wt%, more preferably 2.5-6 wt%. Preferably, the mass ratio of the surfactant to the polyoxyethylene ether phase inversion agent is 1:20-99, more preferably 1:40-95; Preferably, the mixing conditions in step (a) include: a temperature of 30-40°C and a time of 1.5-1h.

13. The phase inversion method according to claim 11, wherein, In step (b), the mass ratio of the phase-inverting emulsion to water is 0.0008-0.008:1, preferably 0.001-0.006:1.

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