Gemini anionic-nonionic surfactant, preparation and application thereof

Abstract

This invention discloses a gemini-type anionic nonionic surfactant, its preparation, and its application. The general molecular formula of the gemini-type anionic nonionic surfactant is: where N is a nitrogen atom, R1 is a linking group, R2 is a hydrophobic group, and R3 is a hydrophilic group. The preparation method of the gemini-type anionic nonionic surfactant includes: adding a haloalkane to an aliphatic diamine to obtain intermediate (I); adding at least one of ethylene oxide or propylene oxide to intermediate (I) to obtain intermediate (II); and adding a haloalkyl sulfonate / carboxylate to intermediate (II) to obtain the gemini-type anionic nonionic surfactant. The gemini-type anionic nonionic surfactant provided by this invention has high interfacial activity and strong emulsification ability for crude oil. It can form mesophase microemulsions under low concentration conditions, significantly improving oil recovery. Furthermore, its preparation process is simple, and it has broad application prospects in the field of oil extraction.

Description

Technical Field

[0001] This invention relates to a gemini-type anionic nonionic surfactant, its preparation, and its application. Background Technology

[0002] Chemical flooding technology is one of the main technological directions for enhancing oil recovery in my country. Currently, the chemical flooding technologies used domestically mainly include weak-base ternary composite flooding, strong-base ternary composite flooding, and binary composite flooding. These composite flooding technologies have shown significant effects in improving oil recovery. Surfactants play a crucial role in composite flooding, such as reducing oil-water interfacial tension, altering reservoir wettability, and emulsifying and carrying crude oil. Currently used surfactants mainly include heavy alkylbenzenes and petroleum sulfonates. Heavy alkylbenzenes are the main surfactant in ternary composite flooding. Strong-base ternary composite flooding with heavy alkylbenzenes as the main surfactant has been widely promoted and applied in Daqing, achieving significant results in improving oil recovery. Petroleum sulfonates are mainly used in weak-base ternary composite flooding. Weak-base ternary composite flooding and binary composite flooding with petroleum sulfonates as the main surfactant have been field-tested in oilfields such as Daqing, Xinjiang, and Dagang, achieving an oil recovery increase of over 18%, with significant results. However, the limited production capacity of heavy alkylbenzene, an industrial byproduct, and the overly complex composition of aromatic distillate oils, the raw materials for petroleum sulfonates, restrict the scale of on-site applications of heavy alkylbenzene sulfonates and petroleum sulfonates. Therefore, the development of functional surfactants has become one of the key research areas.

[0003] Numerous studies in recent years have revealed the crucial role and significance of emulsification in enhancing oil recovery through chemical flooding. Besides ultra-low interfacial tension, micellar solubilization emulsification is also one of the main mechanisms by which oil recovery is enhanced. Surfactants with lower critical micelle concentrations typically possess strong assembly capabilities, enabling the emulsification and solubilization of crude oil at lower concentrations.

[0004] With the increasing demand for novel surfactants, numerous reports on gemini surfactants have emerged both domestically and internationally. Compared to traditional surfactants, gemini surfactants exhibit lower critical micelle concentrations and can form various complex assembly structures at lower concentrations. Due to their stronger interfacial interactions and assembly capabilities, gemini surfactants also possess significant potential in micelle solubilization and emulsification. Researchers have designed and developed a series of ultra-low tension gemini surfactants. Patent CN102703048A discloses a highly efficient, salt-resistant, high-temperature-resistant oil displacement agent for heavy oil reservoirs containing a diether diphenylsulfonate gemini surfactant. This system can effectively reduce the oil-water interfacial tension by up to 10. -3The concentration is on the order of mN / m, and the chromatographic separation of each component is not obvious, indicating broad application prospects. Patent CN103184042A discloses a gemini surfactant for tertiary oil recovery. This gemini surfactant is produced by reacting alkylbenzene with a dihalogenated hydrocarbon to generate a dialkylbenzene linked by an alkyl group. The dialkylbenzene further reacts with an acid anhydride to produce a gemini alkylbenzene carboxylate surfactant. This gemini alkylbenzene carboxylate surfactant, combined with sodium carbonate and water, is used as a tertiary oil recovery displacement agent. The minimum usage concentration can reach 0.002%–0.005%, and the interfacial tension can reach 10 when the surfactant concentration is above 20 mg / L. -3 mN / m. This demonstrates the significant potential of gemini surfactants in reducing interfacial tension and improving oil displacement. However, these traditional gemini surfactants are primarily used to reduce oil-water interfacial tension; therefore, designing a gemini surfactant with strong emulsifying and solubilizing properties is essential. Summary of the Invention

[0005] This invention provides the following technical solution for the emulsifying and solubilizing ability of gemini surfactants:

[0006] In a first aspect, the present invention provides a gemini-type anionic nonionic surfactant, wherein the gemini-type anionic nonionic surfactant has the following general molecular formula:

[0007]

[0008] Wherein, N is a nitrogen atom, R1 is a linking group, R2 is a hydrophobic group, and R3 is a hydrophilic group.

[0009] In one or more alternative embodiments, the linker group R1 is C m H 2m (m=0~6), C m H 2m-2 (m=0~6) or C m H 2m-6 (m=6~8), where m refers to the number of carbon atoms contained in the linking group R1.

[0010] In one or more optional embodiments, the hydrophobic group R2 is a long-chain alkane C. n H 2n+1 Long-chain olefins C n H 2n-1 or long-chain alkyl aromatics C n H 2n-5 n = 6 to 18, where n refers to the number of carbon atoms in the hydrocarbon chain.

[0011] In one or more optional embodiments, the general structural formula of the hydrophilic group R3 is as follows:

[0012] -AB

[0013] Wherein: A is polyoxyethylene ether (CH2CH2O) i (i=30~60), polyoxypropylene ether (CH2CHCH3O) j (j=30~60) or polyoxyethylene ether (CH2CH2O) i (i=30~60) and polyoxypropylene ether (CH2CHCH3O) j Any combination of (j = 30~60);

[0014] B is an alkyl sulfonate / carboxylate (CH2CO2). - Na + CH2CH2CO2 - Na + COCH=CHCO2 - Na + COCH2CH2CO2 - Na + CH2CH2SO3 - Na + CH2CH2CH2SO3 - Na + CH2CH(OH)CH2SO3 - Na + or CH2CH2CH2CH2SO3 - Na + Any one of them.

[0015] Secondly, the present invention also provides a method for preparing the above-mentioned gemini-type anionic nonionic surfactant, the method comprising:

[0016] (1) Adding a haloalkane to an aliphatic diamine yields intermediate (Ⅰ):

[0017]

[0018] Wherein, R2-X represents a halohydrocarbon, R2 is the hydrophobic group mentioned above, and X is a halogen element;

[0019] (2) Add at least one of ethylene oxide or propylene oxide to intermediate (Ⅰ) and react to obtain intermediate (Ⅱ):

[0020]

[0021] (3) Add haloalkyl sulfonate / carboxylate to intermediate (II) to react and obtain a gemini-type anionic nonionic surfactant:

[0022]

[0023] Where BY represents a haloalkyl sulfonate / carboxylate, B is the aforementioned alkyl sulfonate / carboxylate, and Y is a halogen element.

[0024] In one or more optional embodiments, step (1) is as follows: dissolve the aliphatic diamine in an organic solvent, heat under reflux, add the haloalkane dropwise to the aliphatic diamine to react, and after the reaction is complete, wash, filter and purify the product to obtain intermediate (Ⅰ).

[0025] In one or more optional embodiments, the method is as follows:

[0026] (1) Add aliphatic diamine and organic solvent to a three-necked flask, stir for 5 minutes at room temperature, then heat to reflux, slowly add haloalkanes, and continue the reaction after the addition is complete; after the reaction is complete, transfer the mixture to a beaker, add n-hexane, filter to obtain solid, wash the obtained solid with ethyl acetate and n-hexane several times, recrystallize three times with ethyl acetate and alcohol solution to obtain hydrobromide of the product, dissolve the hydrobromide of the product in 20% sodium hydroxide solution, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and further purify to obtain intermediate (Ⅰ);

[0027] (2) Add intermediate (Ⅰ) and an equimolar amount of potassium hydroxide to the high-pressure reactor, and stir while passing nitrogen gas to remove oxygen from the reactor; then raise the temperature and pass cooling water, and introduce at least one of ethylene oxide or propylene oxide into the reactor to keep the reactor pressure at 0.2-0.8 MPa and the temperature at 100-170°C. Continue to add ethylene oxide or propylene oxide and react until the pressure drops to near atmospheric pressure. Stop heating and finally add organic acid to neutralize potassium hydroxide to obtain intermediate (Ⅱ).

[0028] (3) Add intermediate (II) to the three-necked flask, heat and stir until melted, add haloalkyl sulfonate / carboxylate to disperse the haloalkyl sulfonate / carboxylate in intermediate (II), then add an equimolar amount of inorganic base to the three-necked flask, control the reaction temperature to 30-80℃, and continue the reaction to obtain a gemini-type anionic nonionic surfactant.

[0029] In one or more optional embodiments, the molar ratio of aliphatic diamine to haloalkanes in step (1) is 1:2.2 to 2.6.

[0030] In one or more optional embodiments, the aliphatic diamine is any one of ethylenediamine, propylenediamine, butylenediamine, N-ethylbutylenediamine, pentanediamine, hexanediamine, or N,N-diphenyldiamine.

[0031] In one or more alternative embodiments, the halogenated hydrocarbon refers to any one of chloroalkanes, bromoalkanes, or iodoalkanes.

[0032] In one or more optional embodiments, the reaction temperature of step (1) is 70–125°C.

[0033] In one or more alternative embodiments, the molar ratio of the intermediate (Ⅰ) to ethylene oxide or propylene oxide is 1:30 to 60.

[0034] In one or more alternative embodiments, the molar ratio of the intermediate (II) to the haloalkyl sulfonate / carboxylate is 1:2 to 3.

[0035] In one or more optional embodiments, the haloalkyl sulfonate / carboxylate is any one of sodium 2-chloroacetate, sodium 2-bromoacetate, sodium 3-chloropropionate, sodium chlorosulfonate, sodium 2-chloroethylsulfonate, sodium 2-bromoethylsulfonate, sodium 3-chloropropylsulfonate, or sodium 3-bromopropylsulfonate.

[0036] Thirdly, the present invention also proposes an application of the above-mentioned gemini-type anionic nonionic surfactant in oil extraction.

[0037] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0038] (1) The gem-type anionic nonionic surfactant provided by the present invention has high interfacial activity and strong emulsification ability of crude oil. It can form mesophase microemulsions under low concentration conditions, which can greatly improve the recovery rate.

[0039] (2) The gem-type anionic nonionic surfactant provided by the present invention has good solubility, does not undergo phase separation precipitation, and is easy to prepare and use;

[0040] (3) The gemini-type anionic surfactant provided by the present invention can change the overall polarity and molecular weight of the molecule by adjusting the length of the A chain in the hydrophilic group R3, and thus can be applied to oil reservoirs with different temperatures, salinity and crude oil types.

[0041] (4) The preparation process of this invention is simple, the raw materials are cheap and readily available, the cost is low, and it is easy to realize large-scale industrial production of the product. It has great application prospects and potential. Attached Figure Description

[0042] Figure 1 The interfacial properties of different concentrations of gemini-type anionic nonionic surfactants in Example 4;

[0043] Figure 2 The interfacial properties of the oil displacement system with different concentrations of gemini-type anionic nonionic surfactants in Example 5;

[0044] Figure 3 This refers to the emulsion state of the oil displacement system with different concentrations of gemini-type anionic nonionic surfactants in Example 5;

[0045] Figure 4 This is the emulsion state of the oil displacement system with different concentrations of anionic nonionic surfactants in Comparative Example 1. Detailed Implementation

[0046] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Process parameters not specified in the following embodiments are generally performed under conventional conditions.

[0047] The endpoints and any values ​​of the ranges disclosed in this invention 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 in this invention.

[0048] The following provides a detailed description of various specific embodiments of a gemini-type anionic nonionic surfactant and its preparation and application, as provided in the embodiments of the present invention.

[0049] Example 1

[0050] (1) Add 0.5 mol of propylenediamine and 300 mL of isopropanol to a 1,000 mL three-necked flask, stir for 5 minutes at room temperature, then heat to reflux, and slowly add 1.2 mol of hexadecane bromide dropwise using a constant pressure dropping funnel, controlling the addition to be completed in 2 hours. After the addition is completed, continue the reaction for 12 hours. After the reaction is completed, transfer the mixture to a beaker, add n-hexane, filter to obtain a solid, wash the obtained solid several times with ethyl acetate and n-hexane, recrystallize three times from ethyl acetate and ethanol to obtain a white solid, which is the hydrobromide of the product. Dissolve the hydrobromide in 20% sodium hydroxide solution, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and further purify to obtain intermediate (Ⅰ).

[0051] (2) Add 0.2 mol of intermediate (Ⅰ) and an equimolar amount of potassium hydroxide to a 500 mL high-pressure reactor while stirring and purging with nitrogen to remove oxygen from the reactor. Then raise the temperature to 168 °C and purge with cooling water. Introduce ethylene oxide into the reactor to maintain the pressure at 0.3-0.6 MPa and the temperature at 162 °C-178 °C. Continue adding ethylene oxide until the amount added reaches 12 mol. Continue the reaction until the pressure drops to near atmospheric pressure, then stop heating. Finally, add formic acid to neutralize the potassium hydroxide to obtain intermediate (Ⅱ).

[0052] (3) Add 0.1 mol of intermediate (II) to a three-necked flask, heat and stir until melted, add 0.22 mol of sodium 2-chloroethyl sulfonate to disperse it in intermediate (II), then add an equal amount of sodium hydroxide to the three-necked flask, control the reaction temperature to 70℃, and continue the reaction for 8 hours to obtain a gemini-type anionic nonionic surfactant.

[0053] Example 2

[0054] 0.5 mol of ethylenediamine and 350 mL of ethanol were added to a 1,000 mL three-necked flask. The mixture was stirred at room temperature for 5 minutes, then heated to reflux. 1.15 mol of bromododecane was slowly added dropwise using a constant-pressure dropping funnel over 2 hours. After the addition was complete, the reaction was continued for 12 hours. After the reaction was complete, the mixture was transferred to a beaker, and n-hexane was added. The mixture was filtered to obtain a solid. The solid was washed several times with ethyl acetate and n-hexane. The solid was recrystallized three times from ethyl acetate and isopropanol to obtain a white solid, which was the hydrobromide of the product. The hydrobromide of the product was dissolved in 20% sodium hydroxide solution, extracted with ethyl acetate, and the organic phase was dried over anhydrous sodium sulfate. The solvent was then removed by rotary evaporation, and the product was further purified to obtain intermediate (I).

[0055] 0.2 mol of intermediate (Ⅰ) and an equimolar amount of potassium hydroxide were added to a 500 mL high-pressure reactor while stirring and purging with nitrogen to remove oxygen from the reactor. The temperature was then raised to 165 °C and cooling water was introduced. Propylene oxide was introduced into the reactor to maintain the pressure at 0.3-0.5 MPa and the temperature at 160 °C-175 °C. Propylene oxide was added until the amount reached 12 mol. The reaction continued until the pressure dropped to near atmospheric pressure, at which point heating was terminated. Finally, acetic acid was added to neutralize the potassium hydroxide, yielding intermediate (Ⅱ).

[0056] Add 0.1 mol of intermediate (II) to a three-necked flask, heat and stir until melted, add 0.21 mol of sodium 2-chloroacetate to disperse it in intermediate (II), then add an equimolar amount of sodium hydroxide to the three-necked flask, control the reaction temperature at 70℃, and continue the reaction for 12 h to obtain a gemini-type anionic nonionic surfactant.

[0057] Example 3

[0058] 0.5 mol of propylenediamine and 350 mL of isopropanol were added to a 1,000 mL three-necked flask. The mixture was stirred at room temperature for 5 minutes, then heated to reflux. 1.15 mol of tetradecane bromide was slowly added dropwise using a constant-pressure dropping funnel over 2 hours. After the addition was complete, the reaction was continued for 12 hours. After the reaction was complete, the mixture was transferred to a beaker, hexane was added, and the mixture was filtered to obtain a solid. The solid was washed several times with ethyl acetate and hexane. The solid was recrystallized three times from ethyl acetate and isopropanol to obtain a white solid, which was the hydrobromide of the product. The hydrobromide of the product was dissolved in 20% sodium hydroxide solution, extracted with ethyl acetate, dried over anhydrous sodium sulfate, and then the solvent was removed by rotary evaporation. The product was further purified to obtain intermediate (I).

[0059] 0.2 mol of intermediate (Ⅰ) and an equimolar amount of potassium hydroxide were added to a 500 mL high-pressure reactor while stirring and purging with nitrogen to remove oxygen from the reactor. The temperature was then raised to 165 °C and cooling water was introduced. Propylene oxide was introduced into the reactor, and the pressure was maintained at 0.35–0.55 MPa, and the temperature was maintained at 165 °C–180 °C until 24 mol of propylene oxide was added. Then, 24 mol of ethylene oxide was introduced to continue the reaction until the pressure inside the reactor dropped to near atmospheric pressure. Heating was then stopped, and formic acid was added to neutralize the potassium hydroxide to obtain intermediate (Ⅱ).

[0060] Add 0.1 mol of intermediate (II) to a three-necked flask, heat and stir until melted, add 0.23 mol of sodium 3-chloropropylsulfonate to disperse it in intermediate (II), then add an equimolar amount of sodium hydroxide to the three-necked flask, control the reaction temperature at 65℃, and continue the reaction for 12 hours to obtain a gemini-type anionic nonionic surfactant.

[0061] Example 4

[0062] The product obtained in Example 1 was prepared into a solution, and its interface performance was tested:

[0063] The gemini-type anionic nonionic surfactant prepared in Example 1 was added to formation water and stirred until homogeneous to prepare solutions of different concentrations. The mass percentages of the gemini-type anionic nonionic surfactant were 0.05%, 0.1%, 0.3%, and 0.5%, respectively. The interfacial tension of the surfactant solutions was tested using a TX500C rotating drop interfacial tensiometer. The oil-water mixture used was from an oilfield, the test temperature was 42℃, and the test time was 2 hours. The test results are as follows: Figure 1 As shown.

[0064] from Figure 1As can be seen, the interfacial tension of the system of the gemini-type anionic nonionic surfactant reaches an ultra-low level in the concentration range of 0.05wt% to 0.3%, which indicates that the gemini-type anionic nonionic surfactant prepared in Example 1 has good interfacial properties.

[0065] Example 5

[0066] The product obtained in Example 2 was compounded with heavy alkylbenzene sulfonate and sodium chloride to form an oil displacement agent solution, and its interfacial properties and emulsifying properties were tested:

[0067] The gemini-type anionic nonionic surfactant and heavy alkylbenzene sulfonate prepared in Example 2 were sequentially added to formation water and stirred until homogeneous. The resulting mixed solution, by weight percentage, contained 0.24% of the gemini-type anionic nonionic surfactant and 0.06% of the heavy alkylbenzene sulfonate. Sodium chloride was added to the above mixed solution to prepare oil displacement agent solutions containing 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, and 1.2% sodium chloride, respectively.

[0068] The interfacial tension of the above-mentioned oil displacement agent solution was tested using a TX500C rotating drop interfacial tensiometer. The oil-water mixture used was from an oilfield. The test temperature was 42℃, and the test time was 2 hours. Its interfacial properties are as follows: Figure 2 As shown, this compound system can achieve ultra-low oil / water interfacial tension under salt concentration conditions of 0.6% to 1.1%.

[0069] Oil displacement agent solutions with different sodium chloride concentrations were mixed with crude oil at a 1:1 oil-to-water volume ratio and placed in beakers. The mixtures were stirred, poured into graduated tubes, and then placed in a 42°C incubator to observe the emulsion state. The emulsion state is as follows: Figure 3 As shown.

[0070] The interfacial and emulsifying properties of the gemini-type anionic nonionic surfactant complex system prepared in Example 2 are shown in Table 1.

[0071] Table 1. Interfacial and emulsifying properties of the gemini-type anionic nonionic surfactant compound system.

[0072]

[0073]

[0074] Example 6

[0075] The product obtained in Example 2 was compounded with heavy alkylbenzene sulfonate and sodium carbonate to form an oil displacement agent solution, and its interfacial properties and emulsifying properties were tested:

[0076] The gemini-type anionic nonionic surfactant and heavy alkylbenzene sulfonate obtained in Example 2 were sequentially added to formation water and stirred until homogeneous. The resulting mixed solution, by weight percentage, contained 0.24% gemini-nonionic surfactant and 0.06% heavy alkylbenzene sulfonate. Sodium carbonate was added to the above mixed solution to prepare oil displacement agent solutions containing 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5% sodium carbonate, respectively.

[0077] The interfacial tension of the above-mentioned oil displacement agent solution was tested using a TX500C rotating drop interfacial tensiometer. The oil and water used were from an oilfield. The test temperature was 42℃ and the test time was 2 hours.

[0078] Oil displacement agent solutions with different sodium carbonate concentrations were mixed with crude oil in a 1:1 oil-to-water volume ratio and placed in beakers. The mixtures were stirred and poured into graduated tubes. The mixtures were then placed in a 42°C constant temperature oven and allowed to stand. The emulsion state was then observed.

[0079] Table 2 shows the ability of the oil displacement agent solution to reduce interfacial tension and form a medium-phase microemulsion under different sodium carbonate concentrations.

[0080] Table 2. Interfacial and emulsifying properties of the Gemini anion-nonsurfactant compound system.

[0081] Salt concentration Interfacial tension (mN / m) Can a mesophase be formed? 0.5％ <![CDATA[9.24×10 -2 ]]> × 0.6％ <![CDATA[2.30×10 -2 ]]> × 0.7％ <![CDATA[6.71×10 -3 ]]> √ 0.8％ <![CDATA[1.55×10 -3 ]]> √ 0.9％ <![CDATA[6.78×10 -4 ]]> √ 1.0％ <![CDATA[2.32×10 -4 ]]> √ 1.1％ <![CDATA[1.59×10 -3 ]]> √ 1.2％ <![CDATA[5.32×10 -3 ]]> √ 1.3％ <![CDATA[8.48×10 -3 ]]> × 1.4％ <![CDATA[1.34×10 -2 ]]> × 1.5％ <![CDATA[3.46×10 -2 ]]> ×

[0082] This compound system can achieve ultra-low oil / water interfacial tension under sodium carbonate concentrations of 0.7% to 1.3%, and can form mesophase microemulsions under sodium carbonate concentrations of 0.7% to 1.2%.

[0083] Comparative Example 1

[0084] This comparative example is the comparative example of Example 6, which tests the interfacial and emulsifying properties of a widely used anionic nonionic surfactant for oil displacement, fatty alcohol polyoxyethylene ether carboxylate, under different sodium carbonate concentrations.

[0085] The above-mentioned surfactant was dissolved in formation water to prepare a surfactant solution with a mass concentration of 0.3%. Then, sodium carbonate was added to the above surfactant solution to prepare oil displacement agent solutions containing 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, and 1.3% sodium carbonate, respectively.

[0086] The interfacial tension of a surfactant solution was tested using a TX500C rotating drop interfacial tensiometer. The oil and water used were from an oil field, the test temperature was 42℃, and the test time was 2 hours.

[0087] Oil displacement agent solutions with different salt concentrations were mixed with crude oil in a 1:1 oil-to-water volume ratio and placed in beakers. The mixtures were stirred and poured into graduated tubes. The mixtures were then placed in a 42°C constant temperature oven and allowed to stand. The emulsion state was observed.

[0088] Table 3 shows the ability of the oil displacement agent solution to reduce interfacial tension and form a medium-phase microemulsion under different sodium carbonate concentrations. Figure 4 As shown.

[0089] Table 3. Interfacial and emulsifying properties of a commonly used anionic and nonionic surfactant.

[0090] Salt concentration Interfacial tension (mN / m) Can a mesophase be formed? 0.7％ <![CDATA[1.81×10 -2 ]]> × 0.8％ <![CDATA[3.03×10 -2 ]]> √ 0.9％ <![CDATA[8.12×10 -3 ]]> × 1.0％ <![CDATA[5.54×10 -2 ]]> × 1.1％ <![CDATA[1.27×10 -2 ]]> × 1.2％ <![CDATA[1.45×10 -2 ]]> × 1.3％ <![CDATA[2.18×10 -2 ]]> ×

[0091] This surfactant can only achieve ultra-low oil / water interfacial tension at a sodium carbonate concentration of 0.9%, and forms a medium-phase microemulsion only at a sodium carbonate concentration of 0.8%. The salt concentration range required for this surfactant to achieve ultra-low interfacial tension and form a medium-phase microemulsion is significantly smaller than that of the gemini-type anionic nonionic surfactant provided in this invention, indicating that the gemini-type anionic nonionic surfactant provided in this invention has better interfacial properties and emulsifying and solubilizing capabilities, making it suitable for widespread application in the oil extraction field.

[0092] Example 7

[0093] The oil displacement efficiency of the oil displacement agent systems prepared in Examples 5, 6, and Comparative Example 1 at different water permeability levels was evaluated through core flooding experiments. The specific steps are as follows: In a core saturated with oil, formation water was injected for water flooding to a water cut of 98%, then 0.5 PV of oil displacement agent slug was injected, and finally post-water flooding was performed to a water cut of 98%. The produced oil, water, and injection pressure were recorded, and the recovery rate was calculated.

[0094] The core samples used were 3.8*30cm Bailey cores. The experimental temperature was 42℃, and the displacement rate was 0.3mL / min. The oil displacement agents used were mixtures of the oil displacement agent systems prepared in Examples 5, 6, and Comparative Example 1 with polymers. The polymers used had a molecular weight of 25 million and a concentration of 0.12%. The experimental results show that the oil displacement system capable of forming a mid-phase microemulsion enhances the oil recovery rate by more than 33% after water flooding, indicating that the mid-phase microemulsion oil displacement agent provided by this invention has significant advantages in the field of enhanced oil recovery.

[0095] Table 4 shows the oil displacement efficiency of the oil displacement agent systems prepared in Examples 5 and 6 and Comparative Example 1.

[0096]

[0097] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All modifications or applications made in accordance with the above embodiments are within the scope of protection of this technical solution.

[0098] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. A gemini-type anionic nonionic surfactant, characterized in that, The gemini-type anionic nonionic surfactant has the following general molecular formula: Where N is a nitrogen atom; R1is C j H 2j , C k H 2k-2 or C l H 2l-6 ; wherein j, k, 1 indicate the number of carbon atoms contained in R1, j = 0-6 and j is not 0, k = 0-6 and k is not 0 and 1, 1 = 6-8; R2 is a long-chain alkane C. n H 2n+1 or long-chain olefin C n H 2n-1 n = 6 to 18, where n refers to the number of carbon atoms in the hydrocarbon chain; The general formula for R3 is as follows: -AB Wherein: A is polyoxyethylene ether, polyoxypropylene ether, or any combination of polyoxyethylene ether and polyoxypropylene ether; the structural formula of polyoxyethylene ether is (CH2CH2O). i In the formula, i = 30–60; the structural formula of polyoxypropylene ether is (CH2CHCH3O). j In the formula, j = 30~60; B is CH2 CO2 containing sulfonic acid or carboxylic acid groups. - Na + CH2 CH2 CO2 - Na + COCH=CHCO2 - Na + COCH2 CH2CO2 - Na + CH2 CH2 SO3 - Na + CH2 CH2 CH2 SO3 - Na + CH2 CH(OH)CH2 SO3 - Na + or CH2 CH2 CH2CH2 SO3 - Na + Any one of them.

2. A method for preparing the gemini-type anionic nonionic surfactant of claim 1, characterized in that, The method includes: (1) Adding a haloalkane to an aliphatic diamine yields intermediate (Ⅰ); the reaction equation is as follows: ； (2) Add at least one of ethylene oxide or propylene oxide to intermediate (Ⅰ) and react to obtain intermediate (Ⅱ); the reaction equation is as follows: ； (3) Add haloalkyl sulfonate / carboxylate to intermediate (II) to react and obtain a gemini-type anionic nonionic surfactant; the reaction equation is as follows: 。 3. The method as described in claim 2, characterized in that: The step (1) is as follows: dissolve the aliphatic diamine in an organic solvent, heat it under reflux, add the haloalkane dropwise to the aliphatic diamine to react, and after the reaction is complete, wash, filter and purify the product to obtain intermediate (Ⅰ).

4. The method as described in claim 3, characterized in that, The method is as follows: (1) Add aliphatic diamine and organic solvent to a three-necked flask, stir for 5 minutes at room temperature, then heat to reflux, slowly add haloalkanes, and continue the reaction after the addition is complete; after the reaction is complete, transfer the mixture to a beaker, add n-hexane, filter to obtain solid, wash the obtained solid with ethyl acetate and n-hexane several times, recrystallize three times with ethyl acetate and alcohol solution to obtain hydrobromide of the product, dissolve the hydrobromide of the product in 20% sodium hydroxide solution, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and further purify to obtain intermediate (Ⅰ); (2) Add intermediate (Ⅰ) and an equimolar amount of potassium hydroxide to the high-pressure reactor, and purge with nitrogen while stirring to remove oxygen from the reactor; then raise the temperature and purge with cooling water, and introduce at least one of ethylene oxide or propylene oxide into the reactor to keep the reactor pressure at 0.2-0.8 MPa and the temperature at 100-170°C. Continue to add ethylene oxide or propylene oxide and continue the reaction until the pressure drops to near atmospheric pressure. Terminate heating and finally add organic acid to neutralize potassium hydroxide to obtain intermediate (Ⅱ). (3) Add intermediate (II) to the three-necked flask, heat and stir until melted, add haloalkyl sulfonate / carboxylate to disperse the haloalkyl sulfonate / carboxylate in intermediate (II), then add an equimolar amount of inorganic base to the three-necked flask, control the reaction temperature to 30-80℃, and continue the reaction to obtain a gemini-type anionic nonionic surfactant.

5. The method as described in claim 4, characterized in that, In step (1), the molar ratio of aliphatic diamine to haloalkanes is 1:2.2 to 2.

6.

6. The method as described in claim 4, characterized in that, The aliphatic diamine is any one of ethylenediamine, propylenediamine, butanediamine, pentanediamine, or hexanediamine.

7. The method as described in claim 4, characterized in that, The halogenated hydrocarbons refer to any one of chloroalkanes, bromoalkanes, or iodoalkanes.

8. The method as described in claim 4, characterized in that, The reaction temperature in step (1) is 70–125 °C.

9. The method as described in claim 4, characterized in that, The molar ratio of the intermediate (Ⅰ) to ethylene oxide or propylene oxide is 1:30 to 60.

10. The method as described in claim 7, characterized in that, The molar ratio of intermediate (II) to haloalkyl sulfonate / carboxylate is 1:2 to 3.

11. The method as described in claim 4, characterized in that, The haloalkyl sulfonate / carboxylate is any one of sodium 2-chloroacetate, sodium 2-bromoacetate, sodium 3-chloropropionate, sodium chlorosulfonate, sodium 2-chloroethylsulfonate, sodium 2-bromoethylsulfonate, sodium 3-chloropropylsulfonate, or sodium 3-bromopropylsulfonate.

12. The application of the gemini-type anionic nonionic surfactant as described in claim 1 in oil extraction.

Images