Stable-dispersion amphiphilic silicon-organic hybrid nano oil displacement agent and preparation method thereof

Abstract

The invention discloses a dispersion-stable amphiphilic silicon-organic hybrid nano oil displacement agent and a preparation method thereof, and belongs to the technical field of nano oil displacement agents. According to the invention, tetraethyl orthosilicate is used as a silicon source to synthesize a nano silicon dioxide material which is small in particle size and easy to disperse under an oil bath heating condition, amino modification is realized through a'one-pot method 'and a polydopamine coating strategy, and then combination of a silicon-organic hybrid nano material and an amphiphilic group is successfully realized through a condensation reaction. The nano oil-displacing agent is prepared. The nano oil-displacing agent prepared by the invention is not easy to agglomerate and has excellent dispersion stability; as a surfactant, the nano oil-displacing agent shows excellent emulsifying property and interfacial activity on various alkanes such as toluene, normal octane, cyclohexane and the like. The silicon-organic hybrid nano oil displacement agent provided by the invention can be used for preparing a water-oil two-phase emulsion system with a high emulsification rate (100%), and the emulsion system is dense in emulsified bubbles, small in emulsion droplet particle size and excellent in stability.

Description

Technical Field

[0001] This invention belongs to the field of nano-oil displacement agent technology, specifically relating to a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent and its preparation method. Background Technology

[0002] In oil extraction, primary and secondary recovery methods (such as waterflooding) can only recover 30% to 50% of the crude oil. The remaining oil is often difficult to recover due to capillary forces, low permeability, or reservoir heterogeneity. To improve oil recovery, current technologies mainly rely on chemical flooding (such as polymer flooding and surfactant flooding), but various problems still exist. For example, in actual oilfield flooding applications, polymer flooding agents are prone to degradation due to the high salinity or high temperature reservoir environment, resulting in a decrease in flooding efficiency; while surfactant flooding agents suffer significant adsorption losses during use and some contain toxic components, posing a high environmental risk.

[0003] In recent years, nanomaterials (such as SiO2, Al2O3, and carbon nanotubes) have received increasing attention in the oil extraction field due to their small size effect, high specific surface area, and excellent interfacial activity. Among them, silica nanoparticles have attracted much attention due to their high chemical stability, low cost, and ease of surface modification. However, existing silicon-based nano-displacement agents still have many shortcomings. The problem of stable dispersion is an obstacle limiting the application of materials in the field of nano-displacement. Small-sized nanoparticles have high surface energy and are prone to aggregation, affecting their movement in pores. Long-term retention of nanoparticles in pores may cause reservoir blockage and reduce permeability. In addition, partially modified silica nanomaterials often suffer from insufficient wettability control and are usually only suitable for specific environments, with low versatility.

[0004] Addressing the shortcomings of existing chemical flooding agents, nano-flooding agents offer a potential solution for enhancing oil recovery in current oilfield operations. Silica nanoparticles, as a widely available, green, and pollution-free low-cost material, possess significant advantages in the large-scale application of nano-flooding agents. In the harsh environments of high-salt and high-temperature oilfields, silica nanomaterials exhibit superior stability compared to traditional chemical flooding agents, making them more versatile. For tight oil / shale reservoirs, utilizing the small size effect of silica nanoparticles to displace crude oil through nanoscale pores and optimizing the surface activity of silicon-based nano-flooding agents can alter their wettability to the rock formation, which is highly beneficial for improving oil recovery. Exploring the modification of silica nanomaterials using silicon-organic hybridization is a worthwhile approach to improve their performance. Summary of the Invention

[0005] This invention provides a strategy for synthesizing small-particle-size, easily dispersible silicon-organic hybrid nanomaterials, and further provides a dispersion-stable amphiphilic silicon-organic hybrid nano-oil displacement agent and its preparation method.

[0006] The preparation method of the dispersion-stable amphiphilic silicon-organic hybrid nano-oil displacement agent of the present invention comprises the following steps: (1) Add 25%~28% concentrated ammonia water to anhydrous ethanol, stir and disperse until well mixed; then add tetraethyl orthosilicate, heat in an oil bath to react; after the reaction is completed and cooled to room temperature, add n-heptane to promote the flocculation and precipitation of small-diameter silica nanoparticles; then centrifuge to collect the precipitate, and wash with n-heptane to remove impurities, to obtain a semi-transparent jelly-like small-diameter silica nanoparticle gel. (2) Direct synthesis of “surface-aminated silica nanoparticle gel” using the “one-pot method”: 25%~28% concentrated ammonia water by mass fraction was added to anhydrous ethanol and stirred to disperse and mix well; then tetraethyl orthosilicate and 3-aminopropyltriethoxysilane were added step by step and the reaction was heated in an oil bath; after the reaction was completed and cooled to room temperature, n-heptane was added to promote the flocculation and precipitation of small-diameter silica nanoparticles; then the precipitate was collected by centrifugation and washed with anhydrous ethanol and pure water in sequence to remove impurities, and a semi-transparent jelly-like surface-aminated silica nanoparticle gel was obtained. (3) Prepare an aqueous solution of sodium p-aminobenzenesulfonate, and then slowly add an aqueous solution of glutaraldehyde to it. Stir the reaction at room temperature to obtain a solution of the amphiphilic modified group precursor. (4) The small-particle silica nanoparticle gel obtained in step (1) is dispersed in Tris-HCl buffer solution to obtain a small-particle silica nanoparticle gel dispersion; then, dopamine hydrochloride powder is added and oxidized and polymerized at room temperature to obtain an organic-inorganic hybrid aqueous dispersion system of silica / polydopamine. (5) Disperse the surface-aminated silica nanoparticle gel obtained in step (2) into pure water to obtain a surface-aminated silica nanoparticle gel dispersion; then add the amphiphilic modified group precursor solution obtained in step (3), stir the reaction at room temperature, and obtain a stable amphiphilic silicon-organic hybrid nano-oil displacement agent. (6) The amphiphilic modified group precursor solution obtained in step (3) and the silica / polydopamine organic-inorganic hybrid aqueous dispersion system obtained in step (4) are mixed and stirred at room temperature to obtain a stable amphiphilic silicon-organic hybrid nano oil displacement agent. Preferably, in step (1), the volume of concentrated ammonia is 4.0-6.0% of the volume of anhydrous ethanol; the volume of tetraethyl orthosilicate is 2.5-3.5% of the volume of anhydrous ethanol; the oil bath heating temperature is 65-75℃, and the oil bath heating time is 18-24h; the volume of n-heptane that promotes the flocculation and precipitation of small-diameter silica nanoparticles is 1.5-2 times the total volume of the reaction system after the oil bath reaction; Preferably, in step (2), the volume of concentrated ammonia is 4.0-6.0% of the volume of anhydrous ethanol; the volume of tetraethyl orthosilicate is 2.5-3.0% of the volume of anhydrous ethanol; the volume of 3-aminopropyltriethoxysilane (APTES) is 0.3-0.5% of the volume of anhydrous ethanol; the oil bath heating temperature is 65-75℃, and the oil bath heating time is 5-8h; the volume of n-heptane that promotes the flocculation and precipitation of small-diameter silica nanoparticles is 1.5-2 times the total volume of the reaction system after the oil bath reaction; Preferably, in step (3), the concentration of sodium p-aminobenzenesulfonate in the aqueous solution is 80~120 mg / mL, and the mass concentration of glutaraldehyde in the aqueous solution is 25~50%; the reaction time at room temperature (20~25℃) is 6~10 h; and the volume ratio of the aqueous solution of glutaraldehyde to the aqueous solution of sodium p-aminobenzenesulfonate is 1:4~8. Preferably, in step (4) the concentration of small-diameter silica nanoparticle gel in the small-diameter silica nanoparticle gel dispersion is 8~12 mg / mL; the concentration of Tris-HCl buffer solution is 0.05 mol / L and the pH is 8.5; the oxidative polymerization time at room temperature (20~25℃) is 10~15 h. Preferably, in step (5), the concentration of the surface-aminated silica nanoparticle gel is 8-12 mg / mL, the volume of the amphiphilic modified group precursor solution is 10-15% of the volume of pure water, and the stirring reaction time at room temperature (20-25°C) is 4-8 h. Preferably, in step (6), the volume of the amphiphilic modified group precursor solution is 10-15% of the volume of the silica / polydopamine organic-inorganic hybrid aqueous dispersion system; the stirring reaction time at room temperature (20-25°C) is 4-8 hours. The two amphiphilic silicon-organic hybrid nano-oil displacement agents prepared in steps (5) and (6) were mixed with toluene, n-octane, and cyclohexane in a sample bottle at a volume ratio of 1:1. After ultrasonic emulsification, the mixture was allowed to stand for 1 day, and the emulsification rate was measured to detect its amphiphilic properties. The surface tension of the two silicon-organic hybrid nano-oil displacement agents was measured using a surface tension meter, and the interfacial tension of the two phases was measured by mixing them with n-octane, thereby characterizing the interfacial activity of the silicon-organic hybrid nano-oil displacement agents.

[0007] This invention synthesizes easily dispersible nano-silica materials with small particle size using tetraethyl orthosilicate as the silicon source under oil bath heating conditions. A one-pot method and polydopamine coating strategy are employed to achieve surface amination modification of the silica materials. Then, a condensation reaction is used to successfully combine the silicon-organic hybrid nanomaterial with amphiphilic groups, thereby preparing a stable amphiphilic silicon-organic hybrid nano-oil displacement agent. This oil displacement agent is not prone to aggregation and exhibits excellent dispersion stability. Furthermore, as a surfactant, this amphiphilic silicon-organic hybrid nano-oil displacement agent demonstrates excellent emulsifying properties and interfacial activity against various alkanes such as toluene, n-octane, and cyclohexane. The silicon-organic hybrid nano-oil displacement agent obtained by this invention exhibits excellent dispersion stability, certain interfacial activity, and outstanding emulsifying performance. Using this oil displacement agent, a high emulsification rate (100%) water-oil two-phase emulsion system can be prepared. The emulsion system has dense emulsion bubbles, small emulsion droplet size, and excellent stability. Attached Figure Description

[0008] Figure 1 Transmission electron microscope (TEM) image of small-diameter silica nanoparticles prepared in step (1) of Example 1; Figure 2 The infrared absorption spectrum of the surface-aminated silica nanoparticles prepared in step (2) of Example 1; Figure 3 These are photographs of the emulsion systems prepared by mixing nano-oil displacement agent A with toluene, cyclohexane, and n-octane in equal volumes in Example 2. Figure 4 The images show the droplet state and particle size distribution of the emulsion system prepared by mixing nano-oil displacement agent A with toluene, cyclohexane and n-octane in equal volumes in Example 2, as observed under a Leica microscope. Figure 5 Photographs of the emulsion systems prepared by mixing nano-oil displacement agent B with toluene, cyclohexane, and n-octane in equal volumes in Example 3; Figure 6 The images show the droplet state and particle size distribution of the emulsion system prepared by mixing nano-oil displacement agent B with toluene, cyclohexane and n-octane in equal volumes in Example 3, as observed under a Leica microscope. Figure 7 Photographs of emulsion systems prepared by mixing different concentrations of nano-oil displacement agent A and nano-oil displacement agent B with n-octane in equal volumes in Example 4; Figure 8 The surface tension curves are for aqueous dispersion systems of nano-oil displacement agent A and nano-oil displacement agent B at different concentrations in Example 5. Detailed Implementation

[0009] To more clearly describe this invention, a detailed description will be provided below with reference to specific embodiments, which will more clearly demonstrate the features and advantages of this invention. All raw materials and equipment used in this invention can be obtained through normal commercial channels. Any embodiments of this invention obtained directly by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0010] This invention provides a method for preparing a small-sized, highly stable silicon-based nano-oil displacement agent. The invention will be further described below with reference to the accompanying drawings and embodiments: Example 1: (1) Synthesis of "small-diameter silica nanoparticle gel" using tetraethyl orthosilicate as the silicon source: First, 7.5 mL of ammonia water (mass fraction 25%) was added to 150 mL of anhydrous ethanol and stirred until evenly dispersed. Then, 4.8 mL of tetraethyl orthosilicate was slowly added dropwise to the ethanol-ammonia water mixture. The mixture was heated and stirred in an oil bath at 70 °C for 24 h. Heating was stopped and the mixture was cooled to room temperature. At this point, the system was clear, transparent, and slightly blue. Heptane was added to the system at a volume ratio of 1.5 to cause the small-diameter silica nanoparticles to flocculate and precipitate. The silica nanoparticle precipitate was collected by centrifugation at 12000 rpm for 5 minutes. A small amount of heptane was added to the collected bottom precipitate for ultrasonic dispersion, followed by centrifugation and washing to remove impurities. Finally, a semi-transparent, jelly-like small-diameter silica nanoparticle gel was obtained with a solid content of 45.3%. Figure 1 As shown, small-diameter silica nanoparticles were observed using a transmission electron microscope, and their average particle size was found to be 14.01 nm.

[0011] (2) Direct synthesis of "surface-aminated silica nanoparticle gel" using a one-pot method: First, 7.5 mL of ammonia water (mass fraction 25%) was added to 150 mL of anhydrous ethanol and stirred until evenly dispersed. Then, 4.3 mL of tetraethyl orthosilicate and 0.5 mL of 3-aminopropyltriethoxysilane (APTES) were slowly added dropwise to the ethanol-ammonia water mixture. The reaction was heated and stirred in an oil bath at 70 °C for 6 h. Heating was then stopped and the mixture was cooled to room temperature. At this point, the system was clear, transparent, and slightly blue. Heptane was added to the system at a volume ratio of 1.5 to cause the small-diameter silica nanoparticles to flocculate and precipitate. The silica nanoparticle precipitate was collected by centrifugation at 12000 rpm for 5 minutes. A small amount of anhydrous ethanol was added to the collected bottom precipitate, and the mixture was centrifuged and washed to remove impurities. Then, a small amount of pure water was added, and the mixture was centrifuged and washed. Finally, a semi-transparent, jelly-like surface-aminated silica nanoparticle gel was obtained, with a solid content of 30.1%. Figure 2 As shown, the amino modification on the surface of silica nanoparticles was detected using infrared absorption spectroscopy at a wavelength of 3413 cm⁻¹.-1 The peak at 2852 cm⁻¹ is due to the stretching vibration of the amino group (NH₄⁺). -1 and 2925cm -1 The absorption peak at that point originates from the stretching vibration of the saturated CH bond in the methylene group.

[0012] (3) Preparation of amphiphilic modified group precursor: First, 1.213 g of sodium p-aminobenzenesulfonate was added to 12 mL of aqueous solution and stirred at room temperature to dissolve, thus obtaining an aqueous solution of sodium p-aminobenzenesulfonate; then, 2 mL of commercially available glutaraldehyde aqueous solution with a mass concentration of 50% was slowly added to the system and stirred at room temperature. As the reaction proceeded, the color of the system changed from light yellow to dark red and finally maintained a constant color. The amphiphilic modified group precursor solution was prepared after 8 h of reaction. During the reaction, the amino group of sodium p-aminobenzenesulfonate and the aldehyde group of glutaraldehyde underwent a condensation reaction to form a double bond. The double bond interacted with the benzene ring to extend the conjugated system, causing a red shift in the absorption wavelength, which is the main reason for the color change of the system.

[0013] (4) Weigh 100 mg of the small-particle silica nanoparticle gel prepared in step (1) and add it to 10 mL of Tris-HCl buffer solution (0.05 mol / L, pH=8.5). Disperse the gel by ultrasonication to obtain a small-particle silica nanoparticle gel dispersion. Add 2 mg of dopamine hydrochloride powder to the dispersion and disperse it. Stir and oxidize at room temperature for 12 h. The system turns black and polydopamine is successfully coated on the silica surface to obtain an organic-inorganic hybrid aqueous dispersion system of silica / polydopamine.

[0014] (5) 45 mg of the surface-aminated silica nanoparticle gel obtained in step (2) was ultrasonically dispersed in 4.5 mL of pure water system to obtain a surface-aminated silica nanoparticle gel dispersion; 0.5 mL of the amphiphilic modified group precursor solution prepared in step (3) was added to the dispersion system and stirred at room temperature for 5 h to finally obtain a light yellow, dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent, named "nano-oil displacement agent A"; during the reaction, the amino groups on the surface of silica nanoparticles and the excess unreacted aldehyde groups in the amphiphilic modified group precursor further underwent a condensation reaction to achieve the modification of the amphiphilic groups on the silica surface; nano-oil displacement agent A can still maintain a good dispersion state after standing at room temperature for 1 month, and no precipitation was observed.

[0015] (6) Add 0.5 mL of the amphiphilic modified group precursor solution prepared in step (3) to 4.5 mL of the silica / polydopamine organic-inorganic hybrid aqueous dispersion system prepared in step (4), stir at room temperature for 5 h, and finally obtain a black, dispersed, stable amphiphilic silicon-organic hybrid nano oil displacement agent, named "nano oil displacement agent B"; during the reaction, the amino group in polydopamine and the excess unreacted aldehyde group in the amphiphilic modified group precursor further undergo a condensation reaction to achieve the modification of the amphiphilic group on the surface of the nanoparticles; the nano oil displacement agent B can still maintain a good dispersion state after standing at room temperature for 1 month, and no precipitation is observed.

[0016] Example 2: Emulsification performance test of nano-oil displacement agent A in different water-oil mixture systems.

[0017] Take 3 mL of nano-oil displacement agent A and mix it with an equal volume of toluene. Sonicate the mixture for 1 minute in a 270 W ultrasonic instrument to obtain a completely emulsified, pale yellow water-oil two-phase emulsion system. Let the emulsion system stand at room temperature for 6 hours, observe and calculate the emulsification rate. Observe and statistically analyze the distribution of emulsion bubbles using a Leica fluorescence microscope.

[0018] In the above emulsification performance test, toluene was replaced with n-octane, while all other conditions remained completely consistent, to study the emulsification performance of nano-oil displacement agent A on n-octane.

[0019] The toluene in the emulsification performance test above was replaced with cyclohexane, while all other conditions remained completely consistent, to study the emulsification performance of nano-oil displacement agent A for n-octane.

[0020] An emulsion system prepared by nano-oil displacement agent A with toluene, cyclohexane, and n-octane is shown below. Figure 3 As shown, it can still maintain 100% complete emulsification after standing for 6 hours, and the emulsion is stable and uniform. Figure 4 The droplet state of the emulsions under a microscope was shown. The average particle sizes of the three emulsions were 6.73 μm, 5.88 μm and 1.75 μm, respectively, and the particle sizes were uniform.

[0021] Example 3: Emulsification performance test of nano-oil displacement agent B in different water-oil mixture systems.

[0022] Take 3 mL of nano-oil displacement agent B and mix it with an equal volume of toluene. Sonicate the mixture for 1 minute in a 270 W ultrasonic instrument to obtain a completely emulsified, pale yellow water-oil two-phase emulsion system. Let the emulsion system stand at room temperature for 6 hours, observe and calculate the emulsification rate. Observe and count the distribution of emulsion bubbles using a Leica fluorescence microscope.

[0023] In the above emulsification performance test, toluene was replaced with n-octane, while all other conditions remained completely consistent, to study the emulsification performance of nano-oil displacement agent B on n-octane.

[0024] The toluene in the emulsification performance test above was replaced with cyclohexane, while all other conditions remained completely consistent, to study the emulsification performance of nano-oil displacement agent B for n-octane.

[0025] The emulsion system prepared by nano-oil displacement agent B with toluene, cyclohexane, and n-octane is as follows: Figure 5 As shown, it can still maintain 100% complete emulsification after standing for 6 hours, and the emulsion is stable and uniform. Figure 6 The droplet state of the emulsion was shown under a microscope. The average particle sizes of the three emulsions were 5.44 μm, 4.81 μm and 1.55 μm, respectively, and the particle size was uniform.

[0026] Example 4: Emulsification performance tests were conducted on nano-oil displacement agents of different concentrations mixed with n-octane in equal volumes.

[0027] Different concentrations of nano-oil displacement agent A were prepared in 3 mL volumes with water ratios of 1 / 5, 2 / 4, 3 / 3, 4 / 2, 5 / 1, and 6 / 0. These solutions were then mixed with an equal volume of n-octane and sonicated for 1 minute in a 270W ultrasonic instrument to obtain a completely emulsified, pale yellow water-oil two-phase emulsion. The emulsion system was allowed to stand at room temperature for 1 day, and its emulsification state was observed.

[0028] Different concentrations of nano-oil displacement agent B were prepared by mixing 3 mL of water at volume ratios of 1 / 5, 2 / 4, 3 / 3, 4 / 2, 5 / 1, and 6 / 0. Each mixture was then combined with an equal volume of n-octane and sonicated for 1 minute in a 270W ultrasonic instrument to obtain a completely emulsified yellow water-oil two-phase emulsion. The emulsion system was allowed to stand at room temperature for 1 day, and its emulsification state was observed.

[0029] Figure 7 The results show the state of emulsions prepared from nano-displacing agents A and B at different concentrations and with an equal volume of n-octane after standing for 1 day. Clearly, higher concentrations of the displacing agent are beneficial to the stability of the emulsion system. Excessively diluted emulsions are unstable and may experience partial demulsification. For example, when the volume ratio of nano-displacing agent to water is 1 / 5, the emulsification rate of nano-displacing agent A is 85.96%. When the volume ratio of nano-displacing agent A to water is greater than 4 / 2, it still maintains 100% emulsification rate after standing for 1 day. Similarly, when the volume ratio of nano-displacing agent to water is 1 / 5, the emulsification rate of nano-displacing agent B is 79.57%. When the volume ratio of nano-displacing agent B to water is greater than 3 / 3, it can maintain 100% emulsification rate.

[0030] Example 5: The effect of the concentrations of silicon-based nano-oil displacement agents A and B on the surface tension of an aqueous system was investigated using a surface tension meter. The results are as follows: Figure 8 As shown, both nano-displacement agents can reduce the surface tension of water to some extent. The higher the concentration of the displacement agent, the more significant the reduction in surface tension. Nano-displacement agent A exhibits better interfacial activity than nano-displacement agent B. Nano-displacement agent A can reduce the surface tension of water from 71.8 mN / m to 62.8 mN / m, while nano-displacement agent B only reduces the surface tension of water from 71.8 mN / m to 65.3 mN / m. Furthermore, in the nano-displacement agent / n-octane two-phase system, the reduction in interfacial tension between the water and oil phases by the nano-displacement agents is significant. Nano-displacement agents A and B can reduce the interfacial tension from 33.7 mN / m to 19.3 mN / m and 25.6 mN / m, respectively.

Claims

1. A method for preparing a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent, characterized in that: The steps are as follows: (1) Add 25%~28% concentrated ammonia water to anhydrous ethanol, stir and disperse until well mixed; then add tetraethyl orthosilicate, heat in an oil bath to react; after the reaction is completed and cooled to room temperature, add n-heptane to promote the flocculation and precipitation of small-diameter silica nanoparticles; then centrifuge to collect the precipitate, and wash with n-heptane to remove impurities, to obtain a semi-transparent jelly-like small-diameter silica nanoparticle gel. (2) Add 25%~28% concentrated ammonia water to anhydrous ethanol and stir to disperse and mix well; then gradually add tetraethyl orthosilicate and 3-aminopropyltriethoxysilane and heat the reaction in an oil bath; after the reaction is completed and cooled to room temperature, add n-heptane to promote the flocculation and precipitation of small-diameter silica nanoparticles; then centrifuge to collect the precipitate, and wash it with anhydrous ethanol and pure water in sequence to remove impurities, and obtain a semi-transparent jelly-like surface-aminated silica nanoparticle gel. (3) Prepare an aqueous solution of sodium p-aminobenzenesulfonate, and then slowly add an aqueous solution of glutaraldehyde to it. Stir the reaction at room temperature to obtain a solution of the amphiphilic modified group precursor. (4) The small-particle silica nanoparticle gel obtained in step (1) is dispersed in Tris-HCl buffer solution to obtain a small-particle silica nanoparticle gel dispersion; then, dopamine hydrochloride powder is added and oxidized and polymerized at room temperature to obtain an organic-inorganic hybrid aqueous dispersion system of silica / polydopamine. (5) Disperse the surface-aminated silica nanoparticle gel obtained in step (2) into pure water to obtain a surface-aminated silica nanoparticle gel dispersion; then add the amphiphilic modified group precursor solution obtained in step (3), stir the reaction at room temperature, and obtain a stable amphiphilic silicon-organic hybrid nano-oil displacement agent. (6) The amphiphilic modified group precursor solution obtained in step (3) and the silica / polydopamine organic-inorganic hybrid aqueous dispersion system obtained in step (4) are mixed and stirred at room temperature to obtain a stable amphiphilic silicon-organic hybrid nano-oil displacement agent.

2. The method for preparing a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent as described in claim 1, characterized in that: In step (1), the volume of concentrated ammonia is 4.0-6.0% of the volume of anhydrous ethanol; the volume of tetraethyl orthosilicate is 2.5-3.5% of the volume of anhydrous ethanol; the oil bath heating temperature is 65-75℃, and the oil bath heating time is 18-24h; the volume of n-heptane that promotes the flocculation and precipitation of small-diameter silica nanoparticles is 1.5-2 times the total volume of the reaction system after the oil bath reaction.

3. The method for preparing a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent as described in claim 1, characterized in that: In step (2), the volume of concentrated ammonia is 4.0-6.0% of the volume of anhydrous ethanol; the volume of tetraethyl orthosilicate is 2.5-3.0% of the volume of anhydrous ethanol; the volume of 3-aminopropyltriethoxysilane is 0.3-0.5% of the volume of anhydrous ethanol; the oil bath heating temperature is 65-75℃, and the oil bath heating time is 5-8h; the volume of n-heptane that promotes the flocculation and precipitation of small-diameter silica nanoparticles is 1.5-2 times the total volume of the reaction system after the oil bath reaction.

4. The method for preparing a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent as described in claim 1, characterized in that: Step (3) The concentration of sodium p-aminobenzenesulfonate in the sodium p-aminobenzenesulfonate aqueous solution is 80~120mg / mL, and the mass concentration of glutaraldehyde in the glutaraldehyde aqueous solution is 25~50%; the reaction time at room temperature is 6~10h; the volume ratio of glutaraldehyde aqueous solution to sodium p-aminobenzenesulfonate aqueous solution is 1:4~8.

5. The method for preparing a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent as described in claim 1, characterized in that: Step (4): The concentration of small-diameter silica nanoparticle gel in the small-diameter silica nanoparticle gel dispersion is 8~12 mg / mL; the concentration of Tris-HCl buffer solution is 0.05 mol / L and the pH is 8.5; the oxidative polymerization time at room temperature is 10~15 h.

6. The method for preparing a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent as described in claim 1, characterized in that: In step (5), the concentration of the surface-aminated silica nanoparticle gel dispersion is 8-12 mg / mL, the volume of the amphiphilic modified group precursor solution is 10-15% of the volume of pure water, and the stirring reaction time at room temperature is 4-8 h.

7. The method for preparing a dispersed and stable amphiphilic silicon-organic hybrid nano-oil displacement agent as described in claim 1, characterized in that: Step (6) The volume of the amphiphilic modified group precursor solution is 10-15% of the volume of the silica / polydopamine organic-inorganic hybrid aqueous dispersion system; the stirring time at room temperature is 4-8 h.

8. A dispersion-stable amphiphilic silicon-organic hybrid nano-oil displacement agent, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 7.

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