Small-size high-viscosity microemulsion pressure drive integrated system and application

Abstract

The application discloses a small-size high-viscosity microemulsion pressure drive integrated system and application. The small-size high-viscosity microemulsion pressure drive integrated system comprises the following components: 1.75-5.85% of amphiphilic high-molecular surfactant, 2.25-10.15% of auxiliary surfactant, 42.00-48.00% of water and 42.00-48.00% of oil. The preparation method of the amphiphilic high-molecular surfactant comprises the following steps: S1, preparing an organic acid aqueous solution of a polysaccharide compound and adding a short-chain alcohol; S2, adding an alcohol solution of a fatty aldehyde into the system; S3, adding a short-chain alcohol-water solution in which a reducing agent is dissolved into the system in multiple times; and S4, adding an alkali solution into the system until the pH value reaches 8-12. The microemulsion pressure drive integrated system has a wide source of raw materials, is green and environment-friendly, is small in size and can smoothly enter low-permeability and ultra-low-permeability reservoir pores, has high-viscosity characteristics, and has excellent fracturing characteristics, shear resistance and sand carrying performance, so that the purpose of efficient displacement is achieved, and the oil recovery rate of low-permeability and ultra-low-permeability reservoirs is improved.

Description

TECHNICAL FIELD

[0001] The application relates to a small-size high-viscosity microemulsion pressure drive integrated system and application, and belongs to the technical field of efficient oilfield exploitation. BACKGROUND

[0002] China is rich in unconventional oil and gas resources, and the potential is huge. Efficient development of unconventional oil and gas resources has important strategic significance for guaranteeing China's oil and gas safety and optimizing energy structure. However, the geological conditions of unconventional oil and gas are complex, and the reservoir properties are generally poor, which determines that fracturing reconstruction is a necessary measure for industrialized exploitation of oil and gas. The "after-life injury" feature also puts forward strict reservoir protection requirements for reconstruction operations. Conventional water-based fracturing fluid has the characteristics of stratum adsorption, incomplete gel breaking, high residue content, difficult flowback, and the like, and is easy to cause blockage and pollution of porous media, cracks and support agent filling layer, and reduce the permeability, resulting in poor exploitation effect of oil and gas production layer after fracturing, and even cannot produce normally. Therefore, it is urgent to study a reasonable development method for supplementing stratum energy and improving recovery after fracturing development.

[0003] At present, the fracturing-energy-increasing-displacement integrated technology is considered as an important technical means for efficient development of unconventional oil reservoirs, and needs to meet the requirements of "small amount, strong drag reduction, high oil displacement, and low damage" of the pressure drive process. Displacement is a continuous energy supplementing method, especially the chemical displacement system with a size of nanometer, which can combine displacement with imbibition mechanism, can effectively expand the microcosmic swept volume of unconventional oil reservoirs, improve the oil displacement efficiency, and effectively reduce and resolve the water-out and injection failure risks, and is a good follow-up development method for unconventional reservoirs such as tight oil and shale oil. However, for the complex geological conditions of low-permeability and ultra-low-permeability tight oil reservoirs, the chemical oil displacement system which has been applied on a large scale in conventional oil reservoirs has encountered serious challenges, such as serious loss of adsorption, retention and precipitation of surfactants in the migration process, greatly reduced migration distance and oil displacement effect, and the like, which makes the original technical advantages of the chemical oil displacement system unable to effectively play. Therefore, a new pressure drive integrated system which can break through these limitations must be developed to meet the actual application of unconventional oil reservoirs.

[0004] The emergence of microemulsion brings new progress to the integration technology of water flooding and chemical flooding in unconventional reservoirs. Microemulsion is a kind of isotropic, thermodynamically stable, transparent or translucent highly dispersed system formed spontaneously by two immiscible liquids of oil phase and water phase under the action of surfactant and co-surfactant. The particle size of microemulsion is generally 1-100 nm, which has high surface activity, good solubilization and wetting capacity. The formation and arrangement of internal micelles can significantly reduce the adsorption loss of surfactant. In addition, microemulsion also has good viscosity and imbibition function, which can break through the application limit of traditional chemical flooding in unconventional reservoirs, and is expected to become a replacement chemical flooding technology to realize the integration of water flooding and chemical flooding. The results of indoor core imbibition experiment and field huff and puff test have confirmed that microemulsion can effectively improve the imbibition recovery of ultra-low permeability-dense reservoirs, which shows its great development potential in the field of unconventional EOR.

[0005] Currently, anionic surfactants and nonionic surfactants are mainly used to prepare microemulsion for oil displacement. The mixture of equimolar cationic and anionic surfactants can be used to prepare alcohol-free microemulsion, which reduces environmental problems. However, for sandstone reservoirs, due to the negative charge on the rock surface, cationic surfactants are less used for oil displacement, and there are few related literatures in the oil and gas industry. Table 1 lists the viscosity and particle size of microemulsion for oil displacement reported in the literature. It can be found that the existing systems cannot simultaneously meet the small particle size (≤10 nm) and high viscosity characteristics (≥50 mPa·s), which cannot meet the requirements of the integration of water flooding and chemical flooding in low permeability, ultra-low permeability-dense reservoirs. How to improve the viscosity characteristics (≥50 mPa·s) while maintaining the small droplet (≤10 nm) characteristics of microemulsion, increase the scanning volume in micro-nano pore throat, and improve the permeability and displacement efficiency in micro-nano pore matrix, is a major technical problem that needs to be broken through to realize the integration of water flooding and chemical flooding in unconventional reservoirs.

[0006] Table 1 Particle size and viscosity of microemulsion system for oil displacement reported in the literature

[0007]

[0008] The formation and phase transition process of microemulsion depends on the curvature energy (bending energy) of the surfactant oil-water interface film, and its phase behavior is influenced by a variety of factors, important influencing factors are the molecular properties of the surfactant, pressure, temperature, salinity, the application of co-surfactant or cosolvent, water-oil ratio, pH and the properties of the oil. The viscosity of microemulsion can be controlled by the type of hydrocarbon, the type of surfactant, the concentration of electrolyte, the amount of water and the co-surfactant. Due to the rapid development of the surfactant industry, the traditional surfactant has been unable to meet the needs of people's research and application, and the new type of amphiphilic molecules, especially the high molecular surfactant, has become a research hotspot because of its unique properties. Its unique solution aggregation behavior and rheological behavior make it have a wide application prospect in oil and gas fracturing, profile control and water plugging, medical carriers, daily necessities and water treatment industries. The self-assembly of amphiphilic high molecular surfactant is one of the important means to obtain highly ordered structure on the nanometer scale by "bottom-up" method. As a self-assembly building unit, it can be used to grow one-dimensional or two-dimensional nano-micro self-assembly morphology by using crystallization driving, electrostatic interaction and cross-linking interaction as driving force. Therefore, the base material for synthesizing microemulsion for oil displacement is upgraded from conventional surfactant to amphiphilic high molecular surfactant, and the synthesis of amphiphilic high molecular surfactant with controllable hydrophilic and lipophilic groups is introduced into the preparation of microemulsion, which is a key way to realize the small size characteristics of microemulsion and improve its viscosity characteristics, and to obtain a conventional oil reservoir displacement and integration system. SUMMARY

[0009] The purpose of the present application is to provide a small size high viscosity microemulsion displacement and integration system, which has small size characteristics (<10nm) to ensure that it can smoothly enter the low permeability and ultra-low permeability reservoir pores, and high viscosity characteristics (>50mPa·s) to ensure that it has good sand carrying performance and fracturing characteristics. At the same time, the system has excellent oil-water and solid-liquid interface regulation effect, strong wetting reversal ability, and can effectively utilize various residual oils in porous media to achieve the purpose of efficient displacement, and finally realizes the improvement of the recovery rate of low permeability and ultra-low permeability reservoirs.

[0010] The small size high viscosity microemulsion displacement and integration system provided by the present application has the following mass percentage composition:

[0011] The amphiphilic high molecular surfactant is 1.75%-5.85%, the co-surfactant is 2.25%-10.15%, the water is 42.00%-48.00%, and the oil is 42.00%-48.00%.

[0012] The preparation method of the amphiphilic high molecular surfactant includes the following steps:

[0013] S1, preparing an organic acid aqueous solution of a polysaccharide compound, adding a short-chain alcohol, and stirring to obtain a clear and transparent mixed system;

[0014] S2, adding alcohol solution of fatty aldehyde to the mixed system, stirring;

[0015] S3, adding short-chain alcohol-water solution of reducing agent to the mixed system obtained in step S2 in several times (usually 3-5 times), stirring;

[0016] S4, adding alkali solution to the mixed system obtained in step S3 until pH value reaches 8-12.

[0017] In step S1, the mass ratio of the polysaccharide compound to the short-chain alcohol is 1:35-50.

[0018] In step S1, the polysaccharide compound is one of cyclodextrin, poly-D-glucosamine, N-acetylglucosamine, chitin and cellulose;

[0019] The organic acid is one of tartaric acid, citric acid, acetic acid, salicylic acid, oxalic acid and succinic acid;

[0020] The short-chain alcohol is one of ethanol, propanol, 1-propanol, 2-propanol, ethylene glycol and glycerol;

[0021] In step S2, the fatty aldehyde is one of octanal, nonanal, decanal, undecanal, lauryl aldehyde, tridecanal and myristyl aldehyde;

[0022] In step S2, the molar ratio of the polysaccharide compound to the fatty aldehyde is 1:0.005-0.25.

[0023] In step S3, the molar ratio of the polysaccharide compound to the reducing agent is 1:0.005-0.25.

[0024] In step S3, the reducing agent is one of LiAlH4, LiBH4, NaBH4, KBH4 and BH3;

[0025] In step S3, in the short-chain alcohol-water solution of the reducing agent, the volume ratio of the short-chain alcohol to water is 1:2-2:1.

[0026] In step S4, the alkali solution is one of sodium hydroxide solution, potassium hydroxide solution, ammonia solution, sodium carbonate solution and sodium bicarbonate solution.

[0027] In step S3, the time interval for adding the reducing agent is 2-4 hours, and continuous stirring is performed for 24-48 hours after the last addition;

[0028] After step S4, the following post-treatment steps are included: after filtration, washing with ethanol and filtering, repeated for 3-5 times; then washing with deionized water and filtering, repeated for 3-5 times; finally washing once with ethanol and filtering out the product for drying.

[0029] The co-surfactant is one or a combination of two of isopropyl alcohol, triethylene glycol, isopropyl alcohol, n-butyl alcohol, n-pentyl alcohol, iso-pentyl alcohol and n-hexyl alcohol;

[0030] The water is tap water;

[0031] The oil is one of pine oil, octyl dodecanol and white oil.

[0032] The particle size of the integrated system of the present application is 7-9nm, which can ensure its smooth entry into low-permeability and ultra-low-permeability tight oil reservoirs; at 60℃, the shear rate is 170s -1 Under the condition of shearing for 3600s, the viscosity remains basically unchanged in the shear time range, and the viscosity size is maintained at 50-60mPa·s, meeting the requirement of the viscosity of the clean fracturing fluid in the construction process.

[0033] The present application also provides a preparation method of the integrated system, comprising the following steps: uniformly mixing the amphiphilic high-molecular surfactant, the oil and the water, and then adding the co-surfactant dropwise to obtain the integrated system.

[0034] On the basis of the integrated system, the present application also provides a method for improving the recovery of crude oil, comprising the step of using the integrated system for the recovery of crude oil.

[0035] The present application aims at the development bottleneck that the microemulsion for oil displacement cannot simultaneously consider the characteristics of small size and high viscosity, and a kind of amphiphilic high-molecular surfactant is synthesized by original use to prepare a microemulsion system which simultaneously has the characteristics of small size (particle size <10nm) and high viscosity (>50mPa·s).

[0036] The present application has the following beneficial effects:

[0037] (1) The small-size high-viscosity microemulsion pressure drive integrated system of the present application has the small-size characteristic which ensures its smooth entry into low-permeability and ultra-low-permeability reservoir pores, has excellent oil-water and solid-liquid interface regulation effect, has strong wetting reversal ability, can effectively mobilize various residual oils in the porous medium, achieves the purpose of high-efficiency displacement, and finally realizes the improvement of the recovery of crude oil in low-permeability and ultra-low-permeability reservoirs.

[0038] (2) The high-viscosity characteristic of the small-size high-viscosity microemulsion pressure drive integrated system of the present application can ensure that the system has excellent fracturing characteristics, including good shear resistance, at 60℃, the shear rate is 170s -1 Under the condition of shearing for 3600s, the viscosity remains basically unchanged in the shear time range, and the viscosity size is maintained at 50-60mPa·s, meeting the viscosity requirement of the fracturing fluid for oil fields.

[0039] (3) The small-size high-viscosity microemulsion pressure driving integrated system has excellent sand carrying performance, and the settling speed of different proppants in the fracturing fluid is 0.17mm·s -1 -0.71mm·s -1 , which meets the requirements of fracturing operation.

[0040] (4) The small-size high-viscosity microemulsion pressure driving integrated system has wide sources of raw materials, which are obtained from shrimp shells, crab shells, wood and the like, has the characteristics of green environmental protection, thereby reducing the pollution and damage to the formation, and after the oil production operation, it is not necessary to flow back, so that the cost can be greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 It is the appearance photo of the microemulsion in the embodiments 2, 4 and 6 of the application.

[0042] Figure 2 It is the viscosity of the microemulsion under the condition of the shear speed of 170s -1 of the embodiments 2, 4 and 6 of the application. DETAILED DESCRIPTION

[0043] In the following examples, the experimental methods used are conventional methods unless otherwise specified.

[0044] In the following examples, the materials, reagents and the like used are commercially available unless otherwise specified.

[0045] Example 1, preparation of amphiphilic high molecular surfactant

[0046] (1) 2500mL of deionized water was measured by a measuring cylinder and placed in a beaker, 50.0g of chitin was weighed and poured into the beaker, and the magnetic stirrer was stirred until the polysaccharide compound was completely dissolved, and then 2.86mL of 0.10mol / L acetic acid solution was added to the above beaker and stirred for 3 days;

[0047] (2) 2500mL of ethanol was added to the beaker and mixed uniformly, and stirred for 40 minutes until the mixed system was clear and transparent;

[0048] (3) 1.42g of dodecanal was dissolved in 50mL of ethanol solution, and was added dropwise to the above reaction beaker, and stirred for 45 minutes;

[0049] (4) 5.85g of KBH4 was dissolved in a mixed solution of 30mL of water and 30mL of ethanol, and was added to the above reaction beaker in three times with an interval of 2 hours, and after the last addition, continuous stirring was carried out for 48 hours;

[0050] (5) 0.01mol / L NaOH solution was prepared, and was added dropwise to the reaction beaker, and the pH of the solution in the beaker was detected during the dropping, and the pH was required to reach 8.

[0051] (6) Filter out the reaction product, wash and filter with 1000 mL of ethanol, repeat 5 times; then wash and filter with 1000 mL of deionized water, repeat 4 times; finally wash once with 1000 mL of ethanol and filter out the product. Place the product in a container and dry it with a hair dryer for about 24 hours before transferring it to a freeze dryer to dry and obtain an amphiphilic polymeric surfactant.

[0052] Example 2: Preparation of a small-sized, high-viscosity microemulsion hydraulically driven integrated system

[0053] The raw material composition of the small-size, high-viscosity microemulsion hydraulic drive integrated system, by weight percentage:

[0054] Example 1 synthesized an amphiphilic polymeric surfactant of 2.25 wt%, a co-surfactant n-butanol of 5.75 wt%, tap water of 46.00 wt%, and white oil of 46.00 wt%.

[0055] The small-sized, high-viscosity microemulsion hydraulic drive integrated system of this embodiment was prepared through the following steps:

[0056] The amphiphilic polymeric surfactant synthesized in Example 1 was mixed evenly with the oil and aqueous phases, and then a co-surfactant was added dropwise until a clear, transparent, and pale blue mid-phase microemulsion was obtained. Figure 1 (Figure a) shows particles with a diameter of 7–9 nm. At 60°C, the shear rate is 170 s⁻¹. -1 Under a shearing condition of 3600 s, the viscosity remained essentially constant within the shearing time range, maintaining a viscosity of approximately 50 mPa·s. Figure 2 (middle curve a).

[0057] The fracturing fluid undergoes a series of processes upon entering the formation: filtration loss, well-sealing and adsorption, and displacement. In the early stages of the experiment, the core sample needs to be saturated with simulated oil: (1) Simulated filtration loss stage: The fracturing fluid filtration rate is set to 0.1 mL / min, and the temperature to 60℃. The filtration pressure changes are recorded in real time during the filtration process. (2) Simulated well-sealing and adsorption stage: After filtration is complete, the valves on both sides of the clamp are closed, allowing the filtrate to remain in the core sample for a period of time to simulate well-sealing. (3) Simulated displacement stage: At the same temperature and flow rate, the fracturing fluid is used for reverse displacement, and the hydrogen signal intensity and pressure changes inside the core are recorded in real time. The oil recovery rate is calculated based on the changes in hydrogen signal intensity inside the core.

[0058] Further analysis of the final recovery rate of each working fluid system showed that the final recovery rate of the small-size high-viscosity microemulsion hydraulic drive integrated system was 38.6%. The system of this invention has the characteristic of "recovering more" in improving the recovery rate of crude oil in the hydraulic drive development of ultra-low permeability reservoirs.

[0059] Example 3: Synthesis of Amphiphilic Polymer Surfactants

[0060] (1) Measure 3500 mL of deionized water into a beaker using a graduated cylinder, weigh 75.0 g of poly-D-glucosamine and pour it into the beaker, stir with a magnetic stirrer until it is completely wetted, then add 3.25 mL of 0.10 mol / L oxalic acid solution to the above beaker and stir for 3 days until the chitosan is completely dissolved.

[0061] (2) Add 3500 mL of ethanol to the beaker, mix well, and stir for 40 minutes until the mixture is clear and transparent;

[0062] (3) Dissolve 2.90 lauraldehyde in 50 mL of ethylene glycol solution, add it dropwise to the above reaction beaker, and stir for 45 minutes;

[0063] (4) Dissolve 3.56g NaBH4 in a mixed solution of 50mL water and 25mL ethanol, add it to the above reaction beaker in three portions, with an interval of 2 hours between portions, and stir continuously for 48 hours after the last addition.

[0064] (5) Prepare a 0.01 mol / L Na2CO3 solution and add it dropwise into a reaction beaker while checking the pH of the solution in the beaker. The pH should reach 8.

[0065] (6) Filter out the reaction product, wash and filter with 1000 mL of ethanol, repeat 4 times; then wash and filter with 1000 mL of deionized water, repeat 3 times; finally wash once with 1000 mL of ethanol and filter out the product. Place the product in a container and dry it with a hair dryer for about 24 hours before transferring it to a freeze dryer to dry and obtain the amphiphilic polymeric surfactant.

[0066] Example 4: Preparation of a small-sized, high-viscosity microemulsion hydraulically driven integrated system

[0067] The raw material composition of the small-size, high-viscosity microemulsion hydraulic drive integrated system, by weight percentage:

[0068] Example 3 synthesized an amphiphilic polymeric surfactant of 1.75 wt%, a co-surfactant n-butanol of 3.75 wt%, tap water of 47.25 wt%, and white oil of 47.25 wt%.

[0069] The small-sized, high-viscosity microemulsion hydraulic drive integrated system of this embodiment was prepared through the following steps:

[0070] The amphiphilic polymeric surfactant synthesized in Example 3 was mixed evenly with the oil and aqueous phases, and then a co-surfactant was added dropwise until a clear, transparent, and pale blue mid-phase microemulsion was obtained. Figure 1 (Figure b) shows that the particle size is 7-9 nm, and the shear rate is 170 s at 60 °C. -1The viscosity remained basically unchanged in the shear time range, and the viscosity was about 55 mPa s under the shear condition of 3600 s. Figure 2 The middle curve b).

[0071] The final recovery degree of each working fluid system was analyzed according to the method in Example 2, and the final displacement recovery degree of the small-size high-viscosity microemulsion pressure drive integrated system was 40.5%.

[0072] Example 5, synthesis of amphiphilic high molecular surfactant

[0073] (1) 2000 mL of deionized water was measured by a measuring cylinder and placed in a beaker, 40.0 g of poly-D-glucosamine was weighed and poured into the beaker, and the beaker was stirred with a magnet until the poly-D-glucosamine was completely dissolved, and then 4.15 mL of 0.10 mol / L succinic acid was added to the beaker and stirred for 4 days until the poly-D-glucosamine was completely dissolved;

[0074] (2) 2000 mL of ethylene glycol was added to the beaker and mixed evenly, and stirred for 60 minutes until the mixed system was clear and transparent;

[0075] (3) 5.79 g of myristyl aldehyde was dissolved in 60 mL of ethylene glycol solution, and was added dropwise to the above reaction beaker, and stirred for 60 minutes;

[0076] (4) 6.20 g of NaBH4 was dissolved in a mixed solution of 60 mL of water and 60 mL of ethylene glycol, and was added to the above reaction beaker in three times with an interval of 2 hours, and after the last addition, continuous stirring was carried out for 48 hours;

[0077] (5) 0.01 mol / L KOH solution was prepared, and was added dropwise to the reaction beaker, and the pH of the solution in the beaker was detected during the dropwise addition, and the pH was required to reach 10.

[0078] (6) The reaction product was filtered out, washed with 1000 mL of ethanol and filtered, repeated 5 times; then washed with 1000 mL of deionized water and filtered, repeated 4 times; finally, the product was washed once with 1000 mL of ethanol and filtered out and placed in a container, dried for about 24 hours with a hair dryer, and then transferred to a freeze dryer for drying to obtain the amphiphilic high molecular surfactant.

[0079] Example 6, preparation of a small-size high-viscosity microemulsion pressure drive integrated system

[0080] The raw material composition of the small-size high-viscosity microemulsion pressure drive integrated system is as follows in terms of weight percentage:

[0081] The amphiphilic high molecular surfactant synthesized in Example 5 is 1.80 wt%, the co-surfactant n-butanol is 2.40 wt%, tap water is 47.90 wt%, and white oil is 47.90 wt%.

[0082] The small-sized, high-viscosity microemulsion hydraulic drive integrated system of this embodiment was prepared through the following steps:

[0083] The amphiphilic polymeric surfactant synthesized in Example 5 was mixed evenly with the oil and aqueous phases, and then a co-surfactant was added dropwise until a clear, transparent, and pale blue mid-phase microemulsion was obtained. Figure 1 (Figure c) The particle size is 8-9 nm, and the shear rate is 170 s at 60 °C. -1 Under a shearing condition of 3600 s, the viscosity remained essentially constant within the shearing time range, maintaining a viscosity of approximately 58 mPa·s. Figure 2 (Curve c)

[0084] The final recovery rate of each working fluid system was analyzed according to the method in Example 2. The final recovery rate of the small-size high-viscosity microemulsion hydraulic drive integrated system was 41.5%.

Claims

1. A small-sized, high-viscosity microemulsion hydraulic drive integrated system, comprising the following mass percentage components: Amphiphilic polymeric surfactants: 1.75%-5.85%; co-surfactants: 2.25%-10.15%; water: 42.00%-48.00%; oil: 42.00%-48.00%. The preparation method of the amphiphilic polymeric surfactant includes the following steps: S1. Prepare an aqueous solution of polysaccharide compound in organic acid, add short-chain alcohol, and stir to obtain a clear and transparent mixed system; The polysaccharide compound is poly-D-glucosamine or chitosan; S2. Add an alcoholic solution of aliphatic aldehyde to the mixture and stir. S3. Add the short-chain alcohol-water solution containing the reducing agent to the mixed system obtained in step S2 in multiple portions, and stir. S4. Add an alkaline solution to the mixed system obtained in step S3 until the pH value reaches 8-12.

2. The integrated system according to claim 1, characterized in that: In step S1, the organic acid is one of tartaric acid, citric acid, acetic acid, salicylic acid, oxalic acid, and succinic acid; The short-chain alcohol is one of ethanol, propanol, ethylene glycol, and glycerol.

3. The integrated system according to claim 1 or 2, characterized in that: In step S2, the fatty aldehyde is one of octanal, nonanal, decanal, undecanoal, lauraldehyde, tridecanal, and myristal. In step S3, the reducing agent is one of LiAlH4, LiBH4, NaBH4, and KBH4; In step S3, the reducing agent is a short-chain alcohol-water solution, and the volume ratio of the short-chain alcohol to water is 1:2-2:

1. In step S4, the alkaline solution is one of sodium hydroxide solution, potassium hydroxide solution, ammonia solution, sodium carbonate solution, and sodium bicarbonate solution.

4. The integrated system according to claim 1 or 2, characterized in that: In step S3, the time interval for adding the reducing agent is 2 to 4 hours, and after the last addition, the mixture is stirred continuously for 24 to 48 hours. After step S4, the following post-processing steps are included: after filtration, wash with ethanol and filter again, repeating 3-5 times; then wash with deionized water and filter again, repeating 3-5 times; finally wash once with ethanol and filter out the product and dry it.

5. The integrated system according to claim 1 or 2, characterized in that: The co-surfactant is one or a combination of two of isopropanol, triethylene glycol, isopropanol, n-butanol, n-pentanol, isopentanol, and n-hexanol; The water in question is tap water; The oil is one of turpentine, octyldodecyl alcohol, and white oil.

6. The integrated system according to claim 1 or 2, characterized in that: The integrated system has a particle size of 7–9 nm and a shear rate of 170 s. -1 The viscosity is 50-60 mPa·s under shear conditions of 3600 s.

7. A method for preparing the integrated system according to any one of claims 1-6, comprising the following steps: mixing the amphiphilic polymeric surfactant, the oil and the water evenly, and then adding the co-surfactant dropwise.

8. The application of the integrated system according to any one of claims 1-6 in enhancing oil recovery.

9. The application according to claim 8, characterized in that: The integrated system is injected into the formation.

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