A quaternary ammonium salt fluorocarbon hybrid cationic surfactant, a nano oil displacement agent for carbonate rock reservoirs and a method

Abstract

The application provides a quaternary ammonium salt fluorocarbon hybrid cation surfactant, a nano oil displacement agent for carbonate rock oil reservoirs and a method, wherein the quaternary ammonium salt fluorocarbon hybrid cation surfactant is compounded with an anionic surfactant, so that the temperature resistance and salt resistance of the quaternary ammonium salt fluorocarbon hybrid cation surfactant are further improved by virtue of the electrostatic effect of the anion and the cation, and meanwhile, the adsorption of the carbonate rock reservoir to the surfactant is reduced, and a stronger synergistic effect is obtained. Then, the water, the oil and the surfactant are used to form a nano emulsion, so that the oil washing efficiency and the swept volume are maximally improved, and the nano emulsion can be used in a high-temperature and high-salt carbonate rock oil reservoir environment with a temperature of 150 DEG C to 200 DEG C and a salinity of 25x10 4 mg / L, so that the yield is increased and the production is stabilized.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature and high-salinity carbonate reservoir extraction and production enhancement, specifically involving a quaternary ammonium salt fluorocarbon hybrid cationic surfactant, a nano-displacement agent for carbonate reservoirs, and a method thereof. Background Technology

[0002] Carbonate reservoirs, as a special type of oil and gas reservoir, are widely distributed globally. These reservoirs are mainly composed of fracture-pore and karst fracture-vuggy media, with complex and varied reservoir spaces consisting of pores, cavities, fractures, and other morphologies, exhibiting significant scale differences. This unique reservoir structure presents numerous challenges to oilfield development.

[0003] In the early stages of oilfield development, depletion-based extraction is a common method. However, as reserves decrease, water injection gradually becomes the primary development method in the early and mid-stages. However, for carbonate reservoirs, the effectiveness of water injection is not always ideal. Although water injection can displace some crude oil, the oil recovery effect gradually weakens with each injection cycle, and the degree of enhanced oil recovery decreases. This is mainly because water injection cannot reach all areas of the reservoir, especially those areas fragmented by complex structures such as fractures, pores, and caverns.

[0004] To improve the recovery rate of carbonate oil reservoirs, the industry has been exploring various technological approaches. Among them, gas drive technology has been widely recognized and applied. Gas drive technology mainly uses injected gases (such as nitrogen and carbon dioxide) to move crude oil towards production wells. However, gas drive technology also has certain limitations. It primarily utilizes attic oil, that is, crude oil located high in the reservoir that is difficult to displace by water drive. Gas drive technology often fails to reach the remaining oil in other areas.

[0005] Besides gas drive technology, surfactants have always been an important means of enhancing oil recovery. In sandstone reservoirs, surfactants are widely used due to their properties such as improving reservoir wettability, reducing oil-water interfacial tension, and promoting dispersion. However, the application of surfactants in carbonate reservoirs is relatively limited. This is mainly because carbonate reservoirs have some unique properties that make it difficult for conventional surfactants to function effectively.

[0006] First, carbonate reservoirs are mostly high-temperature and high-salinity environments. This environment places extremely high demands on the molecular structure and physicochemical properties of surfactants. Conventional surfactants are easily damaged in high-temperature and high-salinity environments, thus losing their original properties. Therefore, surfactants that can meet the requirements of these high-temperature and high-salinity reservoirs are very limited.

[0007] Secondly, carbonate reservoirs have positively charged rock surfaces, a property distinctly different from sandstone reservoirs, which have negatively charged rock surfaces. Therefore, anionic surfactants suitable for sandstone reservoirs are not applicable to carbonate reservoirs. Large quantities of anionic surfactants are easily adsorbed onto the rock surface in carbonate reservoirs, thus losing their dispersing and solubilizing effects.

[0008] In recent years, nanoemulsions have gradually attracted attention as a novel functional material. Nanoemulsions are systems of tiny droplets composed of water, oil, and surfactants, with droplet diameters typically less than 200 nanometers. Nanoemulsions possess excellent solubilizing properties, low interfacial tension, and good hydrophilic surface wettability. These characteristics make nanoemulsions promising for applications in oilfield development.

[0009] However, developing a highly efficient, temperature- and salt-resistant nano-displacement agent suitable for carbonate reservoirs is no easy task. This requires comprehensive consideration of multiple factors, including the selection of surfactants, the preparation process of nanoemulsions, and their stability under high-temperature and high-salt environments. Only by developing a nano-displacement agent that meets these requirements can the efficiency of oil displacement per ton of water be effectively improved, thereby solving the technical challenges of enhancing oil recovery in carbonate reservoirs. Summary of the Invention

[0010] To address the problems existing in the prior art, this invention provides a quaternary ammonium salt fluorocarbon hybrid cationic surfactant, a nano-displacement agent for carbonate rock oil reservoirs, and a method thereof. The nano-displacement agent prepared using the quaternary ammonium salt fluorocarbon hybrid cationic surfactant can withstand temperatures above 150℃ and salt tolerance of 25 × 10⁻⁶. 4 With concentrations above mg / L, it can significantly reduce oil-water interfacial tension, alter rock wettability, and reduce adsorption loss, thus significantly improving the recovery rate of high-temperature and high-salinity oil reservoirs.

[0011] To achieve the above objectives, the present invention provides the following technical solution: a quaternary ammonium salt fluorocarbon hybrid cationic surfactant, with the following structure: .

[0012] Furthermore, the specific steps are as follows: p-hydroxybenzaldehyde and potassium carbonate were dissolved in a solvent, heated under reflux for 25-35 min, and then perfluorobutylsulfonyl fluoride was added dropwise. After the reaction, the mixture was filtered, the filtrate was evaporated under reduced pressure, the residue was dissolved, extracted, and the resulting organic layer was dried and concentrated to obtain the crude product. The crude product was purified to obtain intermediate 1. Intermediate 1 was dissolved in a solvent and N,N-dimethyl-1,3-diaminopropane was added. Under a protective atmosphere, the mixture was stirred at 30℃~40℃ for 6h~10h. After cooling to room temperature, sodium borohydride was added, and the reaction continued at room temperature. After the reaction was completed, the solution was evaporated, and NaOH solution was added to form an emulsion. The emulsion was filtered to obtain the organic phase. The organic phase was dried, the solvent was removed, and the mixture was purified to obtain intermediate 2. Intermediate 2 and chlorobenzyl methane were added to an EtOH–DMF–CHCl3 solution and stirred at 80℃~100℃ for 5h~8h. After cooling the reaction mixture to room temperature, Et2O was added to obtain the precipitated crude product. The crude product was filtered, washed, and recrystallized to obtain a quaternary ammonium salt fluorocarbon hybrid cationic surfactant.

[0013] Furthermore, the molar ratio of p-hydroxybenzaldehyde, potassium carbonate, and perfluorobutylsulfonyl fluoride is 1:2:1.1~1.4.

[0014] Furthermore, the molar ratio of intermediate 1, N,N-dimethyl-1,3-diaminopropane, and sodium borohydride is 0.6~0.9:1:1.

[0015] Furthermore, the molar ratio of intermediate 2 to chloromethylbenzene is 1:1.01~1.05.

[0016] The present invention also provides the application of the above-mentioned quaternary ammonium salt fluorocarbon hybrid cationic surfactant in high-temperature and high-salinity carbonate reservoirs.

[0017] This invention also provides a nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, comprising a fluorinated surfactant, polyethylene glycol, an oil phase, and water; wherein the fluorinated surfactant is a combination of a quaternary ammonium salt fluorocarbon hybrid cationic surfactant and an anionic surfactant; the structure of the quaternary ammonium salt fluorocarbon hybrid cationic surfactant is as follows: .

[0018] Furthermore, by mass fraction, the composition includes 5%~20% fluorinated surfactant, 1%~8% polyethylene glycol, 5%~10% oil phase, and the balance being water.

[0019] Furthermore, the mass ratio of the quaternary ammonium salt fluorocarbon hybrid cationic surfactant to the anionic surfactant is one of 1:1, 1:2, 1:3, 2:1, or 3:1.

[0020] Furthermore, the anionic surfactant is an α-alkenyl sulfonate, sodium dodecylbenzene sulfonate, or sodium dodecyl sulfate.

[0021] Furthermore, the oil phase is at least one of oleic acid, walnut oil, coconut oil, nano-modified limonene, decane, dodecane, and tetradecane.

[0022] This invention also provides a method for preparing the above-mentioned nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, the specific steps of which are as follows: Fluorinated surfactant, polyethylene glycol, and oil phase are mixed evenly. Water is added dropwise at a speed of 10000 r / min to 2000 r / min to form a crude emulsion. The mixture is stirred continuously for 20 min to 30 min to obtain a mixture. The mixture is ultrasonically treated for 30-40 minutes to obtain a nano-displacement agent for high-temperature, high-salinity carbonate reservoirs.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a quaternary ammonium salt fluorocarbon hybrid cationic surfactant. Through molecular structure design, a benzene ring and short fluorocarbon chains are introduced into the surfactant molecule to prepare a temperature- and salt-resistant surfactant capable of forming ultra-low interfacial tension. In the design of fluorinated surfactants, the carbon-carbon bond structure of the benzene ring is relatively rigid, allowing the entire molecule to maintain a relatively stable structure at high temperatures, making it less prone to decomposition or conformational changes, thus endowing the system with extremely strong heat resistance and adapting to the high-temperature environment of carbonate reservoirs. The π electron cloud in the benzene ring gives it a certain degree of polarity, while also possessing nonpolar carbon-hydrogen bonds. This dual property makes the surfactant with the introduced benzene ring have good affinity with water, alkanes, and crude oil, which is beneficial for the adsorption of surfactant molecules at the oil-water interface. The fluorine atom has extremely high electronegativity, causing the molecules to form a dense arrangement at the oil-water interface, reducing intermolecular repulsion and lowering interfacial tension. The use of short fluorocarbon chains can endow the system with high surface activity while reducing environmental pollution.

[0024] This invention provides a nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs. To achieve better performance and reduce costs, a quaternary ammonium salt fluorocarbon hybrid cationic surfactant is compounded with anionic surfactants. This enhances the temperature and salt resistance through the electrostatic interaction of the cations and anions, while simultaneously reducing the adsorption of surfactants by the carbonate reservoir, resulting in a stronger synergistic effect. A nano-emulsion is then formed using water, oil, and surfactants to maximize oil washing efficiency and swept volume. It can be used at 150℃~200℃ and 25×10⁻⁶ ℃. 4 Increased and stable production can be achieved in high-temperature and high-salinity carbonate reservoir environments with mg / L.

[0025] In summary, the oil displacement agent of this invention remains stable and exhibits excellent oil displacement performance under high-temperature and high-salinity environments. The application of this agent can effectively improve the oil displacement efficiency per ton of water, thereby significantly enhancing the recovery rate of carbonate reservoirs. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0028] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0029] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0030] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0031] In this invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been listed in this document, and "6~22" is simply an abbreviation of these numerical combinations.

[0032] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0033] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0034] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0035] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0036] This invention provides a quaternary ammonium salt fluorocarbon hybrid cationic surfactant, obtained through the following steps: Step 1: Dissolve p-hydroxybenzaldehyde and potassium carbonate in acetonitrile (approximately 2 / 5 volume of a round-bottom flask) and place in a round-bottom flask. Heat under reflux for 25-35 min, then add perfluorobutylsulfonyl fluoride dropwise. Monitor the reaction progress by TLC. After completion, filter to remove excess potassium carbonate. Evaporate the filtrate under reduced pressure. Dissolve the residue in ethyl acetate (1:1 volume ratio to acetonitrile) and extract with brine. Dry the organic layer on anhydrous sodium sulfate, filter and concentrate under vacuum to obtain the crude product. Purify the crude product by column chromatography on silica gel using petroleum ether / ethyl acetate (9:1) as eluent to obtain intermediate 1.

[0037] Step 2: In a round-bottom flask, intermediate 1 was dissolved in methanol (approximately half the volume of the flask), and then N,N-dimethyl-1,3-diaminopropane was added. Under argon atmosphere, the mixture was magnetically stirred at 30-40°C for 6-10 h, cooled to room temperature, and a small amount of sodium borohydride was added. The reaction continued at room temperature. After the reaction was complete (monitored by TLC), the solution was evaporated, and NaOH solution (1:1 volume ratio with methanol) (1.0 M) was added to form an emulsion. This emulsion was transferred to a separating funnel and extracted with ethyl acetate. The organic phase was washed with double-distilled water and brine solution, and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure to obtain the residue, which was purified by silica gel column chromatography using DCM / MeOH (15:1) as the eluent to obtain intermediate 2.

[0038] Step 3: Intermediate 2 and chlorobenzyl methane were added to an EtOH–DMF–CHCl3 (2.5:3:1, 18 ml) solution, and then stirred at 80–100 °C for 5–8 h. After cooling the reaction mixture to room temperature, Et2O was added to obtain the precipitated crude product, which was then filtered and washed with Et2O. The crude product was recrystallized from EtOH and petroleum ether to obtain a quaternary ammonium salt fluorocarbon hybrid cationic surfactant. The structural formula of the quaternary ammonium salt fluorocarbon hybrid cationic surfactant is shown below:

[0039] In step one, the molar ratio of p-hydroxybenzaldehyde, potassium carbonate, and perfluorobutylsulfonyl fluoride is 1:2:1.1~1.4.

[0040] In step two, the molar ratio of intermediate 1, N,N-dimethyl-1,3-diaminopropane, and sodium borohydride is 0.6~0.9:1:1.

[0041] In step three, the molar ratio of intermediate 2 to chloromethylbenzene is 1:1.01~1.05.

[0042] This invention also provides a nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs. Based on the mass of the nano-displacement agent raw material (100%), the components and their mass fractions are as follows: Fluorinated surfactants 5%~20%, Polyethylene glycol 400 1%~8%, Oil phase 5%~10%, The rest is water.

[0043] The surfactant is a combination of the above-mentioned quaternary ammonium salt fluorocarbon hybrid cationic surfactant and anionic surfactant, with a mass ratio of 1:1, 1:2, 1:3, 2:1, or 3:1.

[0044] Preferably, the anionic surfactant is α-alkenyl sulfonate, sodium dodecylbenzene sulfonate, or sodium dodecyl sulfate.

[0045] Preferably, the oil phase is at least one of oleic acid, walnut oil, coconut oil, nano-modified limonene, decane, dodecane, and tetradecane.

[0046] The specific preparation method of the above-mentioned nano-displacement agent for high-temperature and high-salinity carbonate reservoirs is as follows: Step 1: Mix the fluorinated surfactant, polyethylene glycol, and oil phase evenly. Add water dropwise at a speed of 10000r / min to 2000r / min to form a crude emulsion. Stir continuously for 20 min to 30 min to obtain a mixture. Step 2: The mixture is subjected to ultrasonic treatment for 30-40 minutes to obtain a nano-displacement agent for high-temperature, high-salinity carbonate reservoirs.

[0047] Example 1 The synthesis of quaternary ammonium salt fluorocarbon hybrid cationic surfactants is as follows: Step 1: Dissolve 6.11 g of p-hydroxybenzaldehyde and 13.82 g of potassium carbonate in 500 mL of acetonitrile and place in a round-bottom flask. Heat under reflux for 25–35 min, then add 18.13 g of perfluorobutylsulfonyl fluoride dropwise. Monitor the reaction completion by TLC. After completion, filter to remove excess potassium carbonate. Evaporate the filtrate under reduced pressure, dissolve the residue in 500 mL of ethyl acetate, and extract with brine. Dry the organic layer on anhydrous sodium sulfate, filter and concentrate under vacuum to obtain the crude product. Purify the crude product by column chromatography on silica gel using petroleum ether / ethyl acetate (9:1 v / v) to obtain intermediate 1.

[0048] Step 2: In a round-bottom flask, 18.19 g of intermediate 1 was dissolved in 250 mL of methanol, and then 5.11 g of N,N-dimethyl-1,3-diaminopropane was added. The mixture was magnetically stirred at 40 °C for 6 h under an argon atmosphere. After cooling to room temperature, 1.9 g of sodium borohydride was added, and the reaction continued at room temperature. After the reaction was complete, the solution was evaporated, and 250 mL of 1 M NaOH solution was added to form an emulsion. This emulsion was transferred to a separating funnel and extracted with ethyl acetate. The organic phase was washed with double-distilled water and brine, and then dried over anhydrous sodium sulfate to remove residual water. The solvent was removed under reduced pressure, and intermediate 2 was purified by silica gel column chromatography using DCM / MeOH (15:1 v / v) as the eluent.

[0049] Step 3: 14.71 g of intermediate 2 and 3.92 g of chlorobenzyl methane were added to an EtOH–DMF–CHCl3 solution (volume ratio 2.5:3:1, 90 ml), and then stirred at 100 °C for 7 h. After cooling the reaction mixture to room temperature, Et2O was added to obtain the precipitated crude product, which was then filtered and washed with Et2O. The crude product was recrystallized from EtOH and petroleum ether to obtain a quaternary ammonium salt fluorocarbon hybrid cationic surfactant with a yield of 88%. Example 2 A nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, with its components and mass fractions as follows (based on 100% of the raw material): 2% Quaternary ammonium salt fluorocarbon hybrid cationic surfactant Sodium dodecyl sulfate 4%, Polyethylene glycol 4002%, Dodecane 5%, The rest is water.

[0050] The oil displacement agent obtained in this embodiment was used at 25×10 4 A 0.2% aqueous solution of simulated formation water (mg / L) was prepared and aged at 150℃. Surface / interfacial tension, adsorption loss, and oil washing efficiency were then tested. Rock wettability alteration test: Carbonate rock cores were aged in crude oil for 48 hours, then immersed in solutions containing simulated formation water and nano-displacement agent in sealed containers for 36 hours. After drying, the contact angle of the core surface was measured using distilled water to evaluate the ability of the surfactant solution to alter rock wettability. Experimental results are shown in Table 1. Table 1 Performance test of the nano-oil displacement agent obtained in Example 2

[0051] Example 3 A nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, with its components and mass fractions as follows (based on 100% of the raw material): Quaternary ammonium salt fluorocarbon hybrid cationic surfactant 6%, α-Alkenylsulfonate 3%, 5% polyethylene glycol Dodecane 5%, Nano-modified limonene 2% The rest is water.

[0052] The oil displacement agent obtained in this embodiment was used at 25×10 4 A 0.2% aqueous solution of simulated formation water (mg / L) was prepared and aged at 170℃. Surface / interfacial tension, adsorption loss, enhanced oil recovery, and alteration of rock wettability were then tested. The experimental procedure was the same as in Example 2. The results are shown in Table 2. Table 2 Performance test of the nano-oil displacement agent obtained in Example 3

[0053] Example 4 A nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, with its components and mass fractions as follows (based on 100% of the raw material): 9% quaternary ammonium salt fluorocarbon hybrid cationic surfactant Sodium dodecylbenzenesulfonate 3%, 8% polyethylene glycol 10% nano-modified limonene The rest is water.

[0054] The oil displacement agent obtained in this embodiment was used at 25×10 4 A 0.2% aqueous solution of simulated formation water (mg / L) was prepared and aged at 200℃. Surface / interfacial tension, adsorption loss, oil washing efficiency, and alteration of rock wettability were then tested. The experimental results are shown in Table 3. Table 3 Performance test of the nano-oil displacement agent obtained in Example 4

[0055] Example 5 A nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, with its components and mass fractions as follows (based on 100% of the raw material): Quaternary ammonium salt fluorocarbon hybrid cationic surfactant 2.5%, Sodium dodecyl sulfate 2.5%, Polyethylene glycol 4001%, Tetradecane 5%, The rest is water.

[0056] The oil displacement agent obtained in this embodiment was used at 25×10 4A 0.2% aqueous solution of simulated formation water (mg / L) was prepared and aged at 150℃. Surface / interfacial tension, adsorption loss, and oil washing efficiency were then tested. Rock wettability alteration test: Carbonate rock cores were aged in crude oil for 48 hours, then immersed in solutions of simulated formation water and nano-displacement agent in sealed containers for 36 hours. After drying, the contact angle of the core surface was measured using distilled water to evaluate the ability of the surfactant solution to alter rock wettability.

[0057] Example 6 A nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, with its components and mass fractions as follows (based on 100% of the raw material): 5% quaternary ammonium salt fluorocarbon hybrid cationic surfactant Sodium dodecyl sulfate 15%, Polyethylene glycol 4008%, 5% oleic acid The rest is water.

[0058] The oil displacement agent obtained in this embodiment was used at 25×10 4 A 0.2% aqueous solution of simulated formation water (mg / L) was prepared and aged at 150℃. Surface / interfacial tension, adsorption loss, and oil washing efficiency were then tested. Rock wettability alteration test: Carbonate rock cores were aged in crude oil for 48 hours, then immersed in solutions of simulated formation water and nano-displacement agent in sealed containers for 36 hours. After drying, the contact angle of the core surface was measured using distilled water to evaluate the ability of the surfactant solution to alter rock wettability.

[0059] Example 7 A nano-displacement agent for high-temperature, high-salinity carbonate rock oil reservoirs differs from Example 2 in that the oil phase is walnut oil.

[0060] Example 8 A nano-displacement agent for high-temperature, high-salinity carbonate rock oil reservoirs differs from Example 2 in that the oil phase is coconut oil.

[0061] Example 9 A nano-displacement agent for high-temperature, high-salinity carbonate reservoirs differs from Example 2 in that the oil phase is decane.

[0062] Comparative Example 1 Nanoemulsions were prepared according to the method of Example 2, except that a quaternary ammonium salt fluorocarbon hybrid cationic surfactant was used instead of a surfactant compounding system in the formulation. Surface tension, interfacial tension, adsorption loss, and enhanced oil recovery performance were evaluated according to the conditions of Example 2, and the results are shown in Table 4.

[0063] Comparative Example 2 Nanoemulsions were prepared according to the method of Example 2, except that sodium dodecyl sulfate was used instead of surfactant in the formulation. Surface tension, interfacial tension, adsorption loss, and performance enhancement of oil recovery were evaluated according to the conditions of Example 2, and the results are shown in Table 4.

[0064] Comparative Example 3 Nanoemulsions were prepared according to the method of Example 2, except that α-olefin sulfonate was used instead of surfactant in the formulation. Surface tension, interfacial tension, adsorption loss, and performance enhancement were evaluated according to the conditions of Example 2, and the results are shown in Table 4.

[0065] Table 4 Performance evaluation results of Example 2 and Comparative Example

[0066] Comparing the experimental results of Example 2 and Comparative Example 1 in Table 4, it can be seen that the single quaternary ammonium salt fluorocarbon hybrid cationic surfactant has strong interfacial activity, basically consistent with the performance of Example 2, indicating that the combination of anionic and cationic surfactants has a strong synergistic effect and can reduce costs. Comparative Examples 1-3 show that the quaternary ammonium salt fluorocarbon hybrid cationic surfactant has good temperature and salt resistance, and is more suitable for high-temperature and high-salinity carbonate reservoirs.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quaternary ammonium salt fluorocarbon hybrid cationic surfactant, characterized in that, The structure is as follows: 。 2. The method for preparing the quaternary ammonium salt fluorocarbon hybrid cationic surfactant according to claim 1, characterized in that, The specific steps are as follows: p-hydroxybenzaldehyde and potassium carbonate were dissolved in a solvent, heated under reflux for 25-35 min, and then perfluorobutylsulfonyl fluoride was added dropwise. After the reaction, the mixture was filtered, the filtrate was evaporated under reduced pressure, the residue was dissolved, extracted, and the resulting organic layer was dried and concentrated to obtain the crude product. The crude product was purified to obtain intermediate 1. Intermediate 1 was dissolved in a solvent and N,N-dimethyl-1,3-diaminopropane was added. Under a protective atmosphere, the mixture was stirred at 30℃~40℃ for 6h~10h. After cooling to room temperature, sodium borohydride was added, and the reaction continued at room temperature. After the reaction was completed, the solution was evaporated, and NaOH solution was added to form an emulsion. The emulsion was filtered to obtain the organic phase. The organic phase was dried, the solvent was removed, and the mixture was purified to obtain intermediate 2. Intermediate 2 and chlorobenzyl methane were added to an EtOH–DMF–CHCl3 solution and stirred at 80℃~100℃ for 5h~8h. After cooling the reaction mixture to room temperature, Et2O was added to obtain the precipitated crude product. The crude product was filtered, washed, and recrystallized to obtain a quaternary ammonium salt fluorocarbon hybrid cationic surfactant.

3. The method for preparing the quaternary ammonium salt fluorocarbon hybrid cationic surfactant according to claim 2, characterized in that, The molar ratio of p-hydroxybenzaldehyde, potassium carbonate, and perfluorobutyl sulfonyl fluoride is 1:2:1.1~1.

4.

4. The method for preparing the quaternary ammonium salt fluorocarbon hybrid cationic surfactant according to claim 2, characterized in that, The molar ratio of intermediate 1, N,N-dimethyl-1,3-diaminopropane, and sodium borohydride is 0.6~0.9:1:

1.

5. The method for preparing the quaternary ammonium salt fluorocarbon hybrid cationic surfactant according to claim 2, characterized in that, The molar ratio of intermediate 2 to chloromethylbenzene is 1:1.01~1.

05.

6. The application of the quaternary ammonium salt fluorocarbon hybrid cationic surfactant of claim 1 in high-temperature, high-salinity carbonate reservoirs.

7. A nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs, characterized in that, The components include fluorinated surfactants, polyethylene glycol, an oil phase, and water; the fluorinated surfactants are a combination of quaternary ammonium salt fluorocarbon hybrid cationic surfactants and anionic surfactants; the structure of the quaternary ammonium salt fluorocarbon hybrid cationic surfactant is as follows: 。 8. The nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs according to claim 7, characterized in that, By mass fraction, the composition includes 5%~20% fluorinated surfactant, 1%~8% polyethylene glycol, 5%~10% oil phase, and the balance being water.

9. The nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs according to claim 7, characterized in that, The mass ratio of the quaternary ammonium salt fluorocarbon hybrid cationic surfactant to the anionic surfactant is one of 1:1, 1:2, 1:3, 2:1, or 3:

1.

10. The nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs according to claim 7, characterized in that, The anionic surfactant is α-alkenyl sulfonate, sodium dodecylbenzene sulfonate, or sodium dodecyl sulfate.

11. The nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs according to claim 7, characterized in that, The oil phase is at least one of oleic acid, walnut oil, coconut oil, nano-modified limonene, decane, dodecane, and tetradecane.

12. A method for preparing a nano-displacement agent for high-temperature, high-salinity carbonate oil reservoirs according to any one of claims 7 to 11, characterized in that, The specific steps are as follows: Fluorinated surfactant, polyethylene glycol, and oil phase are mixed evenly. Water is added dropwise at a speed of 10000 r / min to 2000 r / min to form a crude emulsion. The mixture is stirred continuously for 20 min to 30 min to obtain a mixture. The mixture is ultrasonically treated for 30-40 minutes to obtain a nano-displacement agent for high-temperature, high-salinity carbonate reservoirs.

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