Preparation method and field application of macromolecular self-coupling profile control and displacement viscosity reducer for thickened oil recovery

Abstract

The invention belongs to the field of oilfield chemical agents, and discloses a preparation method and on-site application of a macromolecular self-coupling profile control and displacement viscosity reducer for thickened oil recovery, the viscosity reducer is synthesized into an acrylate monomer containing a tertiary amine group and an acrylate monomer containing a carboxylic acid group through esterification reaction, a redox initiator is used as an initiation system, and the viscosity reducer is synthesized into a viscosity reducer. A polymer A and a polymer B are prepared through an aqueous solution polymerization method, and then the polymer A and the polymer B are compounded according to the mass ratio of 1: (2-100). Through molecular structure design, a hydrophobic viscosity-reducing group and a hydrophilic profile control group are integrated into a single macromolecular chain, the adsorption resistance is high, the effect is lasting, and the preparation process is mild and easy to industrialize.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical agents, specifically relating to a method for preparing a macromolecular self-coupling viscosity modulator and reducer for heavy oil extraction and its field application. Background Technology

[0002] Heavy oil refers to crude oil with high viscosity and relative density. Its characteristics include high viscosity, high density, poor fluidity, low recovery rate, temperature sensitivity, low content of light components, and high content of gums and asphaltenes. Due to the differences in properties between heavy oil and conventional crude oil, its extraction process differs significantly and cannot be extracted using conventional methods. Heavy oil viscosity can be classified into ordinary heavy oil, extra-heavy oil, and super-heavy oil. After degassing and dehydration at 50℃, ordinary heavy oil has a viscosity of 100–1000 mPa·s, extra-heavy oil has a viscosity of 1000–50000 mPa·s, and super-heavy oil has a viscosity >50000 mPa·s. Studies have shown that crude oil viscosity below 400 mPa·s is suitable for extraction and transportation. Therefore, the core issue in heavy oil extraction is how to effectively reduce the viscosity of crude oil and improve its fluidity.

[0003] Existing heavy oil extraction methods include thermal and cold extraction. While thermal extraction (such as steam flooding and SAGD) effectively reduces oil viscosity, it suffers from high energy consumption, high cost, and high carbon emissions, and its effectiveness is limited in thin or deep heavy oil reservoirs. In contrast, cold extraction methods do not require heating and are often achieved through chemical viscosity reducers, polymer flooding, CO2 injection, microbial action, or physical field assistance. Surfactant-based viscosity reducers, however, suffer from poor temperature and salt resistance, are easily adsorbed and lost, and have limited function, resulting in unstable viscosity reduction effects. Polymer flooding agents, while increasing the viscosity of the displaced phase, have limited viscosity reduction effects on crude oil and pose a risk of pore blockage. Other methods, such as CO2 injection or microbial methods, are complex to operate and have poor adaptability. Currently available chemical viscosity reducers generally have limited function and short-term effects, making it difficult to simultaneously meet the dual functional requirements of "adjustment and displacement" and "viscosity reduction" under reservoir conditions. Summary of the Invention

[0004] To address the shortcomings mentioned in the background section, the present invention aims to provide a method for preparing and applying a macromolecular self-coupling viscosity reducer for heavy oil extraction, solving the problems of limited functionality and poor temperature and salinity resistance of traditional viscosity reducers. The viscosity reducer is composed of polymers A and B in a specific ratio, integrating hydrophobic viscosity-reducing and hydrophilic displacement groups through molecular structure design to achieve synergistic effects. It is suitable for various heavy oil reservoirs, can improve oil recovery, and its preparation process is mild and easily industrialized.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A macromolecular self-coupling viscosity modifier for heavy oil extraction is composed of polymer A and polymer B in a mass ratio of 1:(2-100), wherein:

[0007] The polymer A is obtained by polymerization of acrylate monomers containing tertiary amine groups, which are prepared by esterification reaction of acryloyl chloride with 1,3-bis(N,N-dialkyl)-2-propane-4-hydroxymethylbenzoate.

[0008] The structural formula of the acrylate monomer containing the tertiary amine group is shown in formula (Ⅰ):

[0009] (I)

[0010] In formula (Ⅰ), R1 and R2 are hydrogen atoms or alkyl groups having 6 to 12 carbon atoms;

[0011] The polymer B is obtained by polymerization of acrylate monomers containing carboxylic acid groups, which are prepared by esterification reaction of acryloyl chloride with 2-(3-(hydroxyalkyl)-5-alkoxyphenoxy)acetic acid.

[0012] The structural formula of the acrylate monomer containing the carboxylic acid group is shown in Formula (II):

[0013] (II)

[0014] In equation (II), x ranges from 3 to 11;

[0015] The structural formula of polymer A is shown in formula (III):

[0016] (III)

[0017] The structural formula of polymer B is shown in formula (Ⅳ).

[0018] (IV)

[0019] More preferably, the method for preparing the acrylate monomer containing a tertiary amine group includes the following steps:

[0020] S101. Reaction of epichlorohydrin with an aqueous solution of dialkylamine yields 1,3-bis(N,N-dialkyl)-2-propanol;

[0021] S102. The 1,3-bis(N,N-dialkyl)-2-propanol is subjected to an esterification reaction with p-hydroxymethylbenzoic acid to obtain 1,3-bis(N,N-dialkyl)-2-propane-4-hydroxymethylbenzoate;

[0022] S103. The 1,3-bis(N,N-dialkyl)-2-propane-4-hydroxymethylbenzoate is reacted with acryloyl chloride to prepare the acrylate monomer containing the tertiary amine group.

[0023] More preferably, the method for preparing the acrylate monomer containing a carboxylic acid group includes the following steps:

[0024] S201. React ethyl m-dihydroxybenzoate with a bromoalkane to undergo a substitution reaction, yielding an alkoxy-substituted intermediate.

[0025] S202. After reducing the alkoxy-substituted intermediate, it undergoes a condensation reaction with 2-bromoacetic acid to obtain 2-(3-(hydroxyalkyl)-5-alkoxyphenoxy)acetic acid;

[0026] S203. The 2-(3-(hydroxyalkyl)-5-alkoxyphenoxy)acetic acid is subjected to an esterification reaction with acryloyl chloride to obtain the acrylate monomer containing the carboxylic acid group.

[0027] A method for preparing a macromolecular self-coupling viscosity modifier for heavy oil extraction includes the following steps:

[0028] S1. Synthesize acrylate monomers containing tertiary amine groups and acrylate monomers containing carboxylic acid groups, respectively;

[0029] S2. The acrylate monomer containing tertiary amine groups is polymerized in an aqueous solution to obtain polymer A, and the acrylate monomer containing carboxylic acid groups is polymerized in an aqueous solution to obtain polymer B;

[0030] S3. After gel drying and pulverizing polymer A and polymer B respectively, powdered products A and B are obtained and mixed according to a preset mass ratio to obtain the macromolecular self-coupling viscosity reducer.

[0031] More preferably, the aqueous solution polymerization reaction in step S2 uses a redox initiator system, wherein the oxidant in the redox initiator system is selected from one or more of hydrogen peroxide, ammonium persulfate, potassium persulfate, and tert-butyl hydroperoxide, and the reducing agent is selected from one or more of ferrous ammonium sulfate, sodium sulfite, and sodium bisulfite.

[0032] More preferably, the solid content of the aqueous polymerization reaction solution in step S2 is 10% to 40%; and the amount of the initiator is 0.1% to 2.0% of the total mass of the monomer.

[0033] More preferably, the solid content of the aqueous polymerization reaction solution is 20% to 30%, and the amount of initiator is 0.5% to 1% of the total mass of the monomer.

[0034] More preferably, the polymerization initiation temperature in step S2 is 0℃~30℃, and the polymerization reaction time is 2~8 hours.

[0035] More preferably, the polymerization initiation temperature is 5°C to 10°C, and the polymerization reaction time is 2 to 4 hours.

[0036] The application of a macromolecular self-coupling viscosity modifier in heavy oil reservoir development includes the following steps: preparing the macromolecular self-coupling viscosity modifier into an aqueous solution with a concentration of 800–1600 mg / L, and injecting it into the reservoir via annular reverse injection, wherein the reservoir has a burial depth of 500–2000 m and a formation water salinity of no more than 20000 mg / L.

[0037] The beneficial effects of this invention are:

[0038] This invention provides a macromolecular self-coupling viscosity modifier for heavy oil extraction. Addressing the problems of separation between "regulation" and "viscosity reduction" functions, poor temperature and salt resistance, and short-term effects in current heavy oil development, this invention constructs a novel compound system based on the synergistic copolymerization of bifunctional responsive monomers, achieving adaptive release of both functions under reservoir conditions. The viscosity modifier is composed of two types of functional polymers: Polymer A, derived from acrylate monomers containing tertiary amine groups, possesses significant surface activity and emulsifying viscosity-reducing effects; Polymer B, derived from acrylate monomers containing carboxylic acid groups, can stably exert viscosity-increasing and regulation functions in high-salinity environments. In the heavy oil system, the two polymers form a reversible network structure through various weak interactions such as electrostatic interactions, hydrogen bonding, and hydrophobic association. This not only effectively reduces the apparent viscosity of heavy oil and improves its fluidity but also improves the water-oil mobility ratio, inhibits water channeling, and enhances oil recovery. This invention achieves synergistic self-coupling at the structural level through precise design of the combination of functional groups and molecular segments, overcoming the technical bottleneck of previous viscosity modifiers that could not simultaneously achieve emulsification, depolymerization, and regulation steady-state effects. In practical applications, this viscosity reducer can be implemented through annular reverse injection at low doses of 800–1600 mg / L. It is suitable for medium-deep heavy oil reservoirs with a burial depth of 500–2000 m and a salinity of ≤20000 mg / L, and has good injectability and formation adaptability. Attached Figure Description

[0039] The invention will now be further described with reference to the accompanying drawings.

[0040] Figure 1 The curve shows the relationship between the viscosity of the mixture and the concentration of P3 at 160℃.

[0041] Figure 2 The production curves of the viscosity reducer in this invention before and after cold production of deep ordinary heavy oil horizontal wells are as follows:

[0042] Figure 3This is a comparison chart of oil production in different cycles before and after cold production of deep ordinary heavy oil horizontal wells using the viscosity reducer of this invention;

[0043] Figure 4 This is a production curve and the cumulative oil production of each round of measures when the viscosity reducer of this invention is applied to the combined cold production of medium-deep heavy oil wells. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0045] Example 1

[0046] I. Preparation of acrylate monomers containing tertiary amine groups

[0047] The preparation steps of the acrylate monomer containing the tertiary amine group are as follows: 300 g of dimethylamine aqueous solution (20%) is added to a reactor, stirred, and 46.8 g of epichlorohydrin is slowly added dropwise. After the addition is complete, the temperature is raised to 65℃ and reacted for 16 h. The temperature is then lowered to room temperature, and solid sodium hydroxide is added in slight excess while stirring. The mixture is allowed to stand and separate into layers. The upper pale yellow liquid is separated using a separatory funnel and dried with anhydrous magnesium sulfate to obtain 51 g of pale yellow liquid 1,3-bis(N,N-dimethyl)-2-propanol. 36.5 g of the pale yellow liquid 1,3-bis(N,N-dimethyl)-2-propanol and 38 g of an acetone solution of p-hydroxymethylbenzoic acid are added to the reactor, and concentrated sulfuric acid is added as a catalyst. The mixture is refluxed for 6 h, extracted with dichloromethane and water, and the organic layer is evaporated to dryness to obtain 60 g of white crystalline 1,3-bis(N,N-dialkyl)-2-propane-4-hydroxymethylbenzoate. Dissolve 60 g of the above-prepared sample in chloroform, add potassium carbonate and hydroquinone, and slowly add 27 g of acryloyl chloride dropwise while stirring in an ice-water bath. After the addition is complete, react at 45°C for 24 h, filter, extract the filtrate with dichloromethane and water, evaporate the organic layer to dryness, and recrystallize to obtain 65 g of white crystals, which is the acrylate monomer containing the tertiary amine group.

[0048] II. Preparation of acrylate monomers containing carboxylic acid groups

[0049] The preparation steps of the acrylate monomer containing the carboxylic acid group are as follows: An acetone solution containing 30.8 g of ethyl m-dihydroxybenzoate, 12 g of potassium carbonate, and 2.5 g of 18-crown ether-6 are added to a reactor and stirred for 5 min. Then, 30 g of bromooctane is added, and the mixture is refluxed under stirring for 24 h. After cooling to room temperature, the solvent is removed by vacuum distillation. The residual solid is repeatedly extracted with water and diethyl ether. The organic phase is washed with saturated brine, the solvent is evaporated, and the mixture is purified by silica gel chromatography to obtain 16 g of sample. 3 g of LiAlH4 is added to anhydrous tetrahydrofuran and cooled to 0 °C. 14.3 g of the sample obtained from the above reaction is dissolved in anhydrous tetrahydrofuran and added dropwise to the LiAlH4 tetrahydrofuran solution. The mixture is reacted at room temperature for 12 h. After dissolving in ethyl acetate and water, the precipitate is filtered off, the organic phase is separated, the solvent is evaporated, and the mixture is purified by silica gel chromatography to obtain 10.8 g of sample. 10.8 g of sample was added to acetonitrile, followed by 8 g of K₂CO₃, 7.2 g of NaI, and 12 ml of bromoacetic acid. The mixture was refluxed for 36 h, cooled to room temperature, and the solvent was evaporated under reduced pressure. The sample was extracted with water and dichloromethane, and the organic phase was evaporated to dryness to obtain 21 g of sample. 21 g of sample was dissolved in chloroform, and 10 g of K₂CO₃ and 0.1 g of hydroquinone were added. 18 g of acryloyl chloride was added dropwise below 10 °C, and the mixture was reacted at 45 °C for 24 h. The mixture was filtered, the filtrate was evaporated to dryness, and recrystallized to obtain 22 g of white crystals, which is the acrylate monomer containing the carboxylic acid group.

[0050] III. Macromolecular self-coupling viscosity reducer formed by compounding polymer A and polymer B

[0051] Acrylate monomers containing tertiary amine groups and acrylate monomers containing carboxylic acid groups were synthesized according to the above method. Polymerization was then carried out via aqueous solution using a redox initiation system composed of (NH4)2S2O8-NH4FeSO4 (ferrous ammonium sulfate: ammonium persulfate mass ratio 1:1) to obtain polymer A containing tertiary amine groups and polymer B containing carboxylic acid groups, respectively. The reaction liquid-solid content was 10%, the amount of initiator was 0.1%–2.0% of the total monomer mass, and the reaction temperature was 5°C. The obtained polymer gels were dried and pulverized to obtain powdered products A and B.

[0052] Example 2

[0053] The preparation methods for the acrylate monomers containing tertiary amine groups and the acrylate monomers containing carboxylic acid groups are the same as in Example 1.

[0054] Acrylate monomers containing tertiary amine groups and acrylate monomers containing carboxylic acid groups were synthesized according to the above method. Polymerization was then carried out via aqueous solution using a redox initiation system composed of (NH4)2S2O8-NH4FeSO4 (ferrous ammonium sulfate: ammonium persulfate mass ratio 1:1) to obtain polymer A containing tertiary amine groups and polymer B containing carboxylic acid groups, respectively. The reaction liquid-solid content was 20%, and the amount of initiator was 0.1%–2.0% of the total monomer mass. The reaction temperature was 5°C. The obtained polymer gels were dried and pulverized to obtain powdered products A and B.

[0055] Example 3

[0056] The preparation methods for the acrylate monomers containing tertiary amine groups and the acrylate monomers containing carboxylic acid groups are the same as in Example 1.

[0057] Acrylate monomers containing tertiary amine groups and acrylate monomers containing carboxylic acid groups were synthesized according to the above method. Polymerization was then carried out via aqueous solution using a redox initiation system composed of (NH4)2S2O8-NH4FeSO4 (ferrous ammonium sulfate: ammonium persulfate mass ratio 1:1) to obtain polymer A containing tertiary amine groups and polymer B containing carboxylic acid groups, respectively. The reaction liquid-solid content was 30%, the amount of initiator was 0.1%–2.0% of the total monomer mass, and the reaction temperature was 5°C. The obtained polymer gels were dried and pulverized to obtain powdered products A and B.

[0058] Example 4

[0059] The preparation methods for the acrylate monomers containing tertiary amine groups and the acrylate monomers containing carboxylic acid groups are the same as in Example 1.

[0060] Acrylate monomers containing tertiary amine groups and acrylate monomers containing carboxylic acid groups were synthesized according to the above method. Polymerization was then carried out via aqueous solution using a redox initiation system composed of (NH4)2S2O8-NH4FeSO4 (ferrous ammonium sulfate: ammonium persulfate mass ratio 1:1) to obtain polymer A containing tertiary amine groups and polymer B containing carboxylic acid groups, respectively. The reaction liquid-solid content was 40%, the amount of initiator was 0.1%–2.0% of the total monomer mass, and the reaction temperature was 5°C. The obtained polymer gels were dried and pulverized to obtain powdered products A and B.

[0061] Performance testing

[0062] 1. Viscosity Reduction Performance Test

[0063] To evaluate the actual viscosity-reducing performance of the macromolecular self-coupling viscosity-regulating agent of this invention, heavy oil from the Bohai Oilfield was selected as the test crude oil. Formation wastewater was used to prepare aqueous solutions of polymers A and B obtained in Examples 1-4, each with a concentration of 1600 mg / L. These solutions were then mixed at a mass ratio of 1:2 to obtain a polymer compound solution with a total concentration of 1600 mg / L. The resulting mixed solutions were labeled P1, P2, P3, and P4, corresponding to different types or ratios of polymer components. The test conditions were an oil-water volume ratio of 1:1, a reaction temperature of 60℃ (simulating reservoir conditions), and a stirring reaction time of 1 hour. The viscosity of the treated oil sample was measured using a Brookfield rotational viscometer and compared with a blank sample. The results are shown in Table 1 below.

[0064] Table 1. Viscosity-reducing properties of heavy oil solutions with different polymer solutions

[0065] sample Viscosity (mPa·s) Viscosity retention rate (%) Viscosity reduction rate (%) blank oil sample 5200 100 0.0 <![CDATA[P1]]> 1350 26.0 74.0 <![CDATA[P2]]> 670 12.9 87.1 <![CDATA[P3]]> 540 10.4 89.6 <![CDATA[P4]]> 1245 23.9 76.1

[0066] As shown in Table 1, the viscosity reducers composed of polymers A and B prepared in Examples 1-4 of this invention can significantly reduce the viscosity of heavy oil, with a viscosity reduction rate exceeding 70%, demonstrating excellent viscosity reduction effects. Among them, sample P3 showed the best viscosity reduction effect, with the viscosity reduced to 540 mPa·s and a viscosity reduction rate of 89.6%. This indicates that the composition ratio and structural design of this group are more conducive to the stability of the oil-water interface and the synergistic effect of emulsification and depolymerization, effectively improving the fluidity of crude oil and demonstrating the good application prospects of this invention in heavy oil extraction.

[0067] 2. Viscosity-reducing performance test of macromolecular self-coupling viscosity reducer under high temperature conditions

[0068] The P3 compound system, exhibiting the best viscosity-reducing performance, was selected as a representative sample for high-temperature viscosity-reducing performance evaluation. The tested crude oil was heavy oil from the Bohai Oilfield. P3 polymer solutions of different concentrations were prepared using formation wastewater and mixed with the heavy oil at a 1:1 oil-to-water volume ratio. The resulting mixture was subjected to isothermal treatment at 160℃ with thorough stirring. Subsequently, a Brookfield rotational viscometer was used to measure the apparent viscosity changes of the mixture under different P3 concentrations. A curve showing the relationship between the viscosity of the mixture and the P3 concentration was plotted. The results are shown below. Figure 1 As shown.

[0069] Performance analysis: From Figure 1It can be seen that P3 maintains good viscosity-reducing ability even at a high temperature of 160℃. With increasing P3 concentration, the viscosity of the mixed system shows a significant decreasing trend. When the P3 concentration reaches approximately 800 mg / L, the viscosity reduction rate of heavy oil can be stably maintained above 90%; when the P3 concentration is further increased to approximately 1000 mg / L, the viscosity reduction rate of heavy oil approaches 95%. These results indicate that the viscosity reducer of this invention still possesses strong structural stability and interfacial interaction ability under high-temperature conditions, and by appropriately increasing the injection concentration, the influence of the high-temperature environment on the viscosity-reducing effect can be effectively compensated.

[0070] 3. Macromolecular self-coupling viscosity reducer for cold production of deep ordinary heavy oil horizontal wells

[0071] A deep, conventional heavy oil horizontal well was selected as the field test well. This well was buried at a depth of 1500 meters, with a horizontal section length of 180.5 meters. The sand body showed virtually no water encounter. The porosity of this block is 35%, and the permeability is 2029 × 10⁻⁶. -3 μm 2 This is a high-porosity, high-permeability reservoir. The formation water type in this block is CaCl2, with a chloride ion content of 10200 mg / L and a total salinity of 13530 mg / L. The crude oil viscosity of the well where the treatment was implemented was 13960 mPa·s. The test used cold production technology, without introducing steam or external heating sources. The results of continuous monitoring of the daily fluid volume, daily oil volume, overall water cut, and dynamic fluid level changes before and after the treatment are as follows: Figure 2 As shown, Figure 3 This is a comparison chart of oil production in each cycle before and after cold production using macromolecular autocoupled viscosity modulators.

[0072] Performance analysis: by Figure 2 It can be seen that before the application of the viscosity reducer, the daily oil level fluctuated between 0.9 and 4.3 t / d, which was generally low. After application, the daily oil level began to increase and was significantly higher than the previous level, indicating a significant viscosity reduction and reservoir regulation effect. Furthermore, the overall water cut fluctuated little after application, with no water channeling or increase in water cut observed, indicating that the reservoir regulation agent has good displacement selectivity and oil-water phase separation ability, and will not cause serious water drive channels or disrupt the reservoir equilibrium. Figure 3 It can be seen that the cumulative oil production in each cycle before implementation remained at around 500-1000 tons. In the "post-cold recovery 1" cycle after using macromolecular autocoupling viscosity reducers for cold recovery, the oil production increased significantly, exceeding 2000 tons. Compared with the highest oil production in cycle 6 before implementation, the post-cold recovery oil production increased by nearly 80%.

[0073] 4. Application of composite cold production technology using macromolecular self-coupling viscosity reducers in heavy oil wells

[0074] This field test validated the application of a composite cold production process—combining a macromolecular self-coupling viscosity reducer, a pre-positioned mid-section plug, and post-drive gas—in heavy oil wells. The well was 1280 meters deep with an oil layer thickness of 12.6 meters. The total formation water salinity was 1052 mg / L, and the water type was NaHCO3. The crude oil viscosity at the implemented well was 3518 mPa·s, and the density of the degassed crude oil at the surface was 0.9816 g / cm³. 3 The daily liquid and oil production curves before and after the implementation of the viscosity reducer, as well as the cumulative oil production of each round of measures, are shown in the figure below. Figure 4 As shown.

[0075] Performance analysis: by Figure 4 It can be seen that after adopting the composite cold recovery measures using macromolecular self-coupling viscosity reducer, both daily fluid and daily oil production showed a significant increase; moreover, the cumulative oil recovery from cold recovery far exceeded that of the previous 12 rounds, exceeding 2,500 tons, which is more than twice that of other rounds. This indicates that the viscosity reducer of this invention has a significant viscosity-reducing and production-increasing effect, can effectively activate the utilization of deep heavy oil, and improve reservoir recovery.

Claims

1. A macromolecular self-coupling viscosity reducer for heavy oil extraction, characterized in that, It is composed of polymer A and polymer B in a mass ratio of 1:(2-100), wherein: The polymer A is obtained by polymerization of acrylate monomers containing tertiary amine groups, which are prepared by esterification reaction of acryloyl chloride with 1,3-bis(N,N-dialkyl)-2-propane-4-hydroxymethylbenzoate. The structural formula of the acrylate monomer containing the tertiary amine group is shown in formula (Ⅰ): （Ⅰ）； In formula (Ⅰ), R1 and R2 are hydrogen atoms or alkyl groups having 6 to 12 carbon atoms; The polymer B is obtained by polymerization of acrylate monomers containing carboxylic acid groups, which are prepared by esterification reaction of acryloyl chloride with 2-(3-(hydroxyalkyl)-5-alkoxyphenoxy)acetic acid. The structural formula of the acrylate monomer containing the carboxylic acid group is shown in Formula (II): （Ⅱ）； In equation (II), x ranges from 3 to 11; The structural formula of polymer A is shown in formula (III): (III); The structural formula of polymer B is shown in formula (Ⅳ): （Ⅳ）。 2. The macromolecular self-coupling viscosity reducer according to claim 1, characterized in that, The method for preparing the acrylate monomer containing the tertiary amine group includes the following steps: S101. Reaction of epichlorohydrin with an aqueous solution of dialkylamine yields 1,3-bis(N,N-dialkyl)-2-propanol; S102. The 1,3-bis(N,N-dialkyl)-2-propanol is subjected to an esterification reaction with p-hydroxymethylbenzoic acid to obtain 1,3-bis(N,N-dialkyl)-2-propane-4-hydroxymethylbenzoate; S103. The 1,3-bis(N,N-dialkyl)-2-propane-4-hydroxymethylbenzoate is reacted with acryloyl chloride to prepare the acrylate monomer containing the tertiary amine group.

3. The macromolecular self-coupling viscosity reducer according to claim 1, characterized in that, The method for preparing the acrylate monomer containing a carboxylic acid group includes the following steps: S201. React ethyl m-dihydroxybenzoate with a bromoalkane to undergo a substitution reaction, yielding an alkoxy-substituted intermediate. S202. After reducing the alkoxy-substituted intermediate, it undergoes a condensation reaction with 2-bromoacetic acid to obtain 2-(3-(hydroxyalkyl)-5-alkoxyphenoxy)acetic acid; S203. The 2-(3-(hydroxyalkyl)-5-alkoxyphenoxy)acetic acid is subjected to an esterification reaction with acryloyl chloride to obtain the acrylate monomer containing the carboxylic acid group.

4. A method for preparing a macromolecular self-coupling viscosity modulator for heavy oil extraction, wherein the macromolecular self-coupling viscosity modulator is as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Synthesize acrylate monomers containing tertiary amine groups and acrylate monomers containing carboxylic acid groups, respectively; S2. The acrylate monomer containing tertiary amine groups is polymerized in an aqueous solution to obtain polymer A, and the acrylate monomer containing carboxylic acid groups is polymerized in an aqueous solution to obtain polymer B; S3. After gel drying and pulverizing polymer A and polymer B respectively, powdered products A and B are obtained and mixed according to a preset mass ratio to obtain the macromolecular self-coupling viscosity reducer.

5. The preparation method according to claim 4, characterized in that, The aqueous polymerization reaction in step S2 uses a redox initiator system. The oxidant in the redox initiator system is selected from one or more of hydrogen peroxide, ammonium persulfate, potassium persulfate, and tert-butyl hydroperoxide, and the reducing agent is selected from one or more of ferrous ammonium sulfate, sodium sulfite, and sodium bisulfite.

6. The preparation method according to claim 4, characterized in that, The solid content of the aqueous polymerization reaction solution in step S2 is 10% to 40%; the amount of initiator is 0.1% to 2.0% of the total mass of the monomer.

7. The preparation method according to claim 6, characterized in that, The solid content of the aqueous polymerization reaction solution is 20% to 30%, and the amount of initiator is 0.5% to 1% of the total mass of the monomer.

8. The preparation method according to claim 4, characterized in that, The polymerization initiation temperature in step S2 is 0℃~30℃, and the polymerization reaction time is 2~8 hours.

9. The preparation method according to claim 8, characterized in that, The polymerization initiation temperature is 5℃~10℃, and the polymerization reaction time is 2~4 hours.

10. The application of a macromolecular self-coupling viscosity modifier as described in claim 1 in heavy oil reservoir development, characterized in that, Includes the following steps: The macromolecular self-coupling viscosity reducer was prepared into an aqueous solution with a concentration of 800–1600 mg / L and injected into the reservoir via annular reverse injection. The reservoir had a burial depth of 500–2000 m and a formation water salinity of no more than 20,000 mg / L.

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