A salt-resistant viscosity reducer for thick oil and a preparation method thereof

Abstract

The application discloses a salt-resistant viscosity reducer for thick oil and a preparation method thereof, and relates to the technical field of oil exploitation. In the preparation of the salt-resistant viscosity reducer for thick oil, a modified silane coupling agent is prepared by reacting 3-(methacryloyloxy)propyl trimethoxysilane with trimethylchlorosilane; 0.5-generation polyamide-amine, 1-generation polyamide-amine, 2-generation polyamide-amine and 3-generation polyamide-amine are prepared by sequentially reacting methyl acrylate and ethylenediamine with ethylenediamine as the center; and the salt-resistant viscosity reducer for thick oil is prepared by partially grafting 2-generation polyamide-amine or 3-generation polyamide-amine with the modified silane coupling agent. The salt-resistant viscosity reducer for thick oil prepared by the application has the advantages of salt resistance and good viscosity reduction effect.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, specifically to a heavy oil anti-salt viscosity reducer and its preparation method. Background Technology

[0002] Heavy oil is an important oil and gas resource, playing an increasingly vital role in the world's oil supply. However, in many cases, the low fluidity of heavy oil and the deposition of waxes or asphaltenes causing pipeline blockages make it difficult to transport. Currently, many methods have been proposed to reduce the viscosity of heavy oil to facilitate transportation. Among all viscosity reduction methods, chemical viscosity reduction is considered the most promising due to its economic and technical feasibility and reasonable cost.

[0003] In heavy oil extraction, a significant portion of oilfields have extremely high formation water salinity. Some marine crude oil formation waters contain over 15% salt, more than three times the salinity of seawater. Traditional polyether surfactants and some conventional surfactants lose their activity in such high-concentration brine. Therefore, traditional polyether surfactants and some conventional surfactants cannot be used for viscosity reduction in high-salinity heavy oil. To address this problem, it is necessary to develop salt-resistant viscosity reducers with good viscosity-reducing properties for use in heavy oil extraction. Summary of the Invention

[0004] The purpose of this invention is to provide a heavy oil anti-salt viscosity reducer and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A heavy oil anti-salt viscosity reducer, wherein the heavy oil anti-salt viscosity reducer is prepared by reacting a modified silane coupling agent with a dendritic polyamide-amine.

[0006] As an optimization, the modified silane coupling agent has the following structural formula: ; The grafting rate of the modified silane coupling agent is 40%~50%.

[0007] As an optimization, the dendritic polyamide-amine is obtained by alternating reactions of ethylenediamine and methyl acrylate with ethylenediamine as the core.

[0008] As an optimization, the dendritic polyamide-amine is a second-generation polyamide-amine or a third-generation polyamide-amine.

[0009] As an optimization, the modified silane coupling agent is prepared by reacting 3-(methacryloyloxy)propyltrimethoxysilane with trimethylchlorosilane.

[0010] A method for preparing a heavy oil anti-salt viscosity reducer includes the following preparation steps: Dendritic polyamide-amine was dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, in the dark, at room temperature, at 400-600 rpm, a modified silane coupling agent was uniformly added dropwise over 30-40 minutes. After the addition was complete, the temperature was raised to 30-35°C, and the reaction was carried out at 400-600 rpm for 36-40 hours. The solvent and unreacted modified silane coupling agent were removed by vacuum distillation, and the mixture was vacuum dried at 60-70°C for 10-12 hours to obtain a heavy oil anti-salt viscosity reducer.

[0011] As an optimization, the molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:(1.8~2.2).

[0012] As an optimization, the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:(8~10).

[0013] As an optimization, the preparation method of the modified silane coupling agent includes the following preparation steps: First, 3-(methacryloyloxy)propyltrimethoxysilane and trimethylchlorosilane were mixed evenly. At room temperature, a mixture of water and methanol was added dropwise over 30-60 minutes at 300-400 rpm, controlling the dropping rate to ensure the system temperature was below 50°C. After the addition was complete, the mixture was stirred and refluxed at 300-400 rpm for 16-20 hours at room temperature. The organic layer was separated by standing, washed with water until neutral, dehydrated with anhydrous sodium sulfate, and methanol was removed by vacuum distillation. The fraction at 120-124°C under 3 mmHg was collected by fractional distillation to obtain the modified silane coupling agent.

[0014] As an optimization, the molar ratio of 3-(methacryloyloxy)propyltrimethoxysilane, trimethylchlorosilane, methanol, and water is 1:(6~9):(6~9):(9~13.5).

[0015] As an optimization, the reaction process of the modified silane coupling agent is as follows: .

[0016] As an optimization, the preparation method of the dendritic polyamide-amine includes the following preparation steps: (A) Preparation of 0.5 generation polyamide-amine: The molar ratio of ethylenediamine to methyl acrylate is 1:(7~9), and the mass ratio of ethylenediamine to methanol is 1:(10~12). In an ice-water bath under nitrogen atmosphere, at 200~300 r / min, ethylenediamine is dissolved in methanol. The methanol solution of methyl acrylate is added dropwise uniformly over 30~40 min. The temperature is raised to 20~25℃, and the reaction is stirred at 200~300 r / min for 22~26 h. The methanol and unreacted raw materials are removed by vacuum distillation. After purification, 0.5 generation polyamide-amine is obtained. (B) Preparation of first-generation polyamide-amine: The molar ratio of 0.5-generation polyamide-amine to ethylenediamine is 1:(12~15), and the mass ratio of ethylenediamine to methanol is 1:(4~6). In an ice-water bath under a nitrogen atmosphere, at 200~300 r / min, ethylenediamine is dissolved in methanol. The methanol solution of 0.5-generation polyamide-amine is added dropwise uniformly over 30~40 min. The temperature is raised to 25~30℃, and the reaction is stirred at 200~300 r / min for 22~26 h. Methanol and ethylenediamine are removed by vacuum distillation. After purification, first-generation polyamide-amine is obtained. (C) Preparation of second-generation polyamidoamine: 1.5-generation polyamidoamine was prepared by repeating step (A) with first-generation polyamidoamine instead of ethylenediamine, and second-generation polyamidoamine was prepared by repeating step (B) with 1.5-generation polyamidoamine instead of 0.5-generation polyamidoamine. (D) Preparation of third-generation polyamidoamine: 2.5-generation polyamidoamine is prepared by repeating step (A) with second-generation polyamidoamine instead of ethylenediamine, and third-generation polyamidoamine is prepared by repeating step (B) with 2.5-generation polyamidoamine instead of 0.5-generation polyamidoamine.

[0017] As an optimization, the molar ratio of the first-generation polyamide-amine, methyl acrylate, and ethylenediamine in step (C) is 1:(15~16):(28~32), and the reaction time and reaction temperature of both steps remain unchanged.

[0018] As an optimization, the molar ratio of the second-generation polyamide-amine, methyl acrylate, and ethylenediamine in step (D) is 1:(30~35):(55~60), the reaction time of both steps is extended to 36~40h, and the reaction temperature remains unchanged.

[0019] As an optimization, the reaction process of the 0.5 generation polyamide-amine is as follows: .

[0020] As an optimization, the reaction process of the first-generation polyamide-amine is as follows: .

[0021] As an optimization, the reaction process of the second-generation polyamide-amine is as follows: .

[0022] As an optimization, the reaction process of the third-generation polyamide-amine is as follows: .

[0023] As an optimization, the dendritic polyamide-amine was prepared according to the content recorded in the literature "Application Research of Modified Polyamide-amine in the Treatment of Oily Organic Wastewater".

[0024] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing a heavy oil anti-salt viscosity reducer, the present invention first reacts 3-(methacryloyloxy)propyltrimethoxysilane with trimethylchlorosilane to prepare a modified silane coupling agent; using ethylenediamine as the core, it reacts sequentially with methyl acrylate and ethylenediamine to prepare 0.5-generation polyamide-amine, 1-generation polyamide-amine, 2-generation polyamide-amine, and 3-generation polyamide-amine; the 2-generation polyamide-amine or 3-generation polyamide-amine is partially grafted with the modified silane coupling agent to obtain the heavy oil anti-salt viscosity reducer.

[0025] First, a modified silane coupling agent is prepared by reacting 3-(methacryloyloxy)propyltrimethoxysilane with trimethylchlorosilane. Compared to long-chain alkanes, organosilicon groups have higher bond energies and lower surface energies, exhibiting excellent surface activity and better stability. They can accumulate and arrange themselves into dense molecular films at the interface between two phases, resulting in better spreading and wetting properties. However, the commonly used double-bonded silane coupling agent, 3-(methacryloyloxy)propyltrimethoxysilane, has easily hydrolyzed -OCH3 groups. During use, these groups readily hydrolyze to release active silanols, leading to excessive polymerization and crosslinking, and the generation of a large amount of agglomerates, resulting in flocculation and precipitation, ultimately causing failure. To avoid this, trimethylchlorosilane is used to modify it, transforming the easily hydrolyzed -OCH3 groups into hydrolysis-resistant -OSi(CH3)3 groups. Furthermore, the modified molecule has more terminal methyl groups, which spread like small umbrellas across the two-phase interface, exhibiting excellent surface activity.

[0026] Secondly, using ethylenediamine as the core, it is reacted sequentially with methyl acrylate and ethylenediamine to prepare 0.5-generation polyamide-amine, 1-generation polyamide-amine, 2-generation polyamide-amine, and 3-generation polyamide-amine. 0.5-generation polyamide-amine is prepared by Michael addition reaction of ethylenediamine and methyl acrylate. 1-generation polyamide-amine is then prepared by amidation reaction of 0.5-generation polyamide-amine with ethylenediamine. The Michael addition and amidation reactions are then repeated to obtain 2-generation and 3-generation polyamide-amine. Polyamide-amines contain a large number of amide groups, which have excellent hydrophilic properties. These amide groups, acting as hydrophilic ends, impart good hydrophilicity to the products. Furthermore, they contain a large number of terminal amino groups, which can be used for grafting a variety of functional groups.

[0027] Finally, a partial grafting reaction was carried out between second-generation or third-generation polyamide-amines and modified silane coupling agents to prepare a heavy oil anti-salt viscosity reducer. The double bonds on the modified silane coupling agent react with the terminal amino groups of the polyamide-amine via Michael addition, thereby grafting organosilicon groups onto its surface. Simultaneously, to obtain a product with better surface activity and reduce raw material waste, the grafting rate was controlled by adjusting the amount of modified silane coupling agent added, maintaining a grafting rate of 40%–50%, thus retaining some primary amino groups unreacted. In the grafting reaction of the modified silane coupling agent, due to the steric hindrance of the long grafted segments, pursuing 100% or even grafting two modified silane coupling agent segments onto a single primary amino group would result in excessively long reaction times and low yields. Furthermore, the hydrophilic amide and tertiary amine groups are completely encapsulated within the organosilicon groups, making it difficult for them to contact the aqueous phase. Although the organosilicon groups can still exert their surface activity, the effect is poor. Therefore, by controlling the grafting rate at 40%~50%, some hydrophilic amino groups can be retained, while the density of organosilicon groups is kept within a suitable range. This creates a Janus structure on the polyamide-amine surface that is partly hydrophobic and partly hydrophilic. This structure can better exert surface activity. This excellent surface activity can better emulsify heavy oil and reduce its viscosity. Furthermore, since no ionic groups are used, it also has good salt resistance and can effectively resist the effect of electrolyte compression of the electric double layer in high-salt environments, effectively exerting its viscosity-reducing effect in high-salt environments. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] The raw material information used in all the following examples and comparative examples is as follows: Dendritic polyamide-amine: Third-generation polyamide-amine, prepared as follows: (A) Preparation of 0.5 generation polyamide-amine: The molar ratio of ethylenediamine to methyl acrylate was 1:9, and the mass ratio of ethylenediamine to methanol was 1:11. In an ice-water bath under a nitrogen atmosphere, ethylenediamine was dissolved in methanol at 250 r / min. Methyl acrylate methanol solution was added dropwise uniformly over 35 min. The temperature was raised to 25℃, and the reaction was stirred at 300 r / min for 24 h. Methanol and unreacted raw materials were removed by vacuum distillation. After purification, 0.5 generation polyamide-amine was obtained. (B) Preparation of first-generation polyamide-amine: The molar ratio of 0.5-generation polyamide-amine to ethylenediamine was 1:14, and the mass ratio of ethylenediamine to methanol was 1:6. In an ice-water bath under a nitrogen atmosphere, at 250 r / min, ethylenediamine was dissolved in methanol. The methanol solution of 0.5-generation polyamide-amine was added dropwise uniformly over 35 min. The temperature was raised to 30℃, and the reaction was stirred at 300 r / min for 24 h. Methanol and ethylenediamine were removed by vacuum distillation. After purification, first-generation polyamide-amine was obtained. (C) Preparation of second-generation polyamide-amine: 1.5-generation polyamide-amine was prepared by repeating step (A) with first-generation polyamide-amine instead of ethylenediamine, and second-generation polyamide-amine was prepared by repeating step (B) with 1.5-generation polyamide-amine instead of 0.5-generation polyamide-amine. The molar ratio of first-generation polyamide-amine, methyl acrylate and ethylenediamine was 1:16:30. The reaction time and reaction temperature of both steps remained unchanged. (D) Preparation of third-generation polyamide-amine: 2.5-generation polyamide-amine was prepared by repeating step (A) with second-generation polyamide-amine instead of ethylenediamine, and third-generation polyamide-amine was prepared by repeating step (B) with 2.5-generation polyamide-amine instead of 0.5-generation polyamide-amine. The molar ratio of second-generation polyamide-amine, methyl acrylate and ethylenediamine was 1:32:60. The reaction time of both steps was extended to 36 h, and the reaction temperature remained unchanged.

[0030] Example 1:

[0031] A method for preparing a heavy oil anti-salt viscosity reducer, the method comprising the following preparation steps: (1) The molar ratio of 3-(methacryloyloxy)propyltrimethoxysilane, trimethylchlorosilane, methanol and water is 1:6:6:9. First, 3-(methacryloyloxy)propyltrimethoxysilane and trimethylchlorosilane are mixed evenly. At room temperature, the mixture of water and methanol is added dropwise over 60 min at 300 r / min. The dropping rate is controlled to ensure that the system temperature is less than 50 °C. After the addition is completed, the mixture is stirred and refluxed at 300 r / min for 20 h at room temperature. The organic layer is separated by standing, washed with water until neutral, and dehydrated with anhydrous sodium sulfate. Methanol is removed by vacuum distillation, and the fraction at 120 °C under 3 mmHg is collected by distillation to obtain the modified silane coupling agent. (2) The molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:2.2, and the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:10. The dendritic polyamide-amine is first dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, protected from light, at room temperature, at 400 r / min, the modified silane coupling agent is added dropwise uniformly over 40 min. After the addition is completed, the temperature is raised to 30℃ and the reaction is carried out at 400 r / min for 40 h. The solvent and unreacted modified silane coupling agent are removed by vacuum distillation. The mixture is then vacuum dried at 60℃ for 12 h to obtain a heavy oil anti-salt viscosity reducer.

[0032] The grafting rate of the modified silane coupling agent was 41.37%.

[0033] Example 2:

[0034] A method for preparing a heavy oil anti-salt viscosity reducer, the method comprising the following preparation steps: (1) The molar ratio of 3-(methacryloyloxy)propyltrimethoxysilane, trimethylchlorosilane, methanol and water is 1:7.5:7.5:11.25. First, 3-(methacryloyloxy)propyltrimethoxysilane and trimethylchlorosilane are mixed evenly. At room temperature, a mixture of water and methanol is added dropwise over 45 minutes at 350 r / min. The dropping rate is controlled to ensure that the system temperature is less than 50 °C. After the addition is completed, the mixture is stirred and refluxed at 350 r / min for 18 hours at room temperature. The organic layer is separated by standing, washed with water until neutral, and dehydrated with anhydrous sodium sulfate. Methanol is removed by vacuum distillation, and the fraction at 122 °C under 3 mmHg is collected by distillation to obtain the modified silane coupling agent. (2) The molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:2, and the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:9. The dendritic polyamide-amine is first dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, protected from light, at room temperature, at 500 r / min, the modified silane coupling agent is added dropwise over 35 min. After the addition is completed, the temperature is raised to 35℃ and the reaction is carried out at 500 r / min for 38 h. The solvent and unreacted modified silane coupling agent are removed by vacuum distillation. The mixture is then dried under vacuum at 65℃ for 11 h to obtain a heavy oil anti-salt viscosity reducer.

[0035] The grafting rate of the modified silane coupling agent was 44.89%.

[0036] Example 3:

[0037] A method for preparing a heavy oil anti-salt viscosity reducer, the method comprising the following preparation steps: (1) According to the molar ratio of 3-(methacryloyloxy)propyltrimethoxysilane, trimethylchlorosilane, methanol and water of 1:9:9:13.5, 3-(methacryloyloxy)propyltrimethoxysilane and trimethylchlorosilane are mixed evenly. At room temperature, the mixture of water and methanol is added dropwise over 30 min at 400 r / min. The dropping rate is controlled to ensure that the system temperature is less than 50℃. After the addition is completed, the mixture is stirred and refluxed at 400 r / min for 16 h at room temperature. The organic layer is separated by standing, washed with water until neutral, dehydrated with anhydrous sodium sulfate, methanol is removed by vacuum distillation, and the fraction at 124℃ under 3 mmHg is collected by distillation to obtain the modified silane coupling agent. (2) The molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:1.8, and the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:8. The dendritic polyamide-amine is first dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, protected from light, at room temperature, at 600 r / min, the modified silane coupling agent is uniformly added dropwise over 30 min. After the addition is completed, the temperature is raised to 35℃ and the reaction is carried out at 600 r / min for 36 h. The solvent and unreacted modified silane coupling agent are removed by vacuum distillation. The mixture is then vacuum dried at 70℃ for 10 h to obtain a heavy oil anti-salt viscosity reducer.

[0038] The grafting rate of the modified silane coupling agent was 48.52%.

[0039] Example 4: The preparation method of the heavy oil anti-salt viscosity reducer in Example 4 differs from that in Example 2 in that it uses a different dendritic polyamide-amine, using a second-generation polyamide-amine instead of a third-generation polyamide-amine. The remaining steps are the same as in Example 2.

[0040] The grafting rate of the modified silane coupling agent was 46.58%.

[0041] Comparative Example 1: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 1 differs from that in Example 2 in that step (1) is omitted, and step (2) is modified as follows: the molar ratio of 3-(methacryloyloxy)propyltrimethoxysilane to the primary amino group in dendritic polyamide-amine is 1:2, and the mass ratio of 3-(methacryloyloxy)propyltrimethoxysilane to N,N-dimethylformamide is 1:9. First, the dendritic polyamide-amine is dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, protected from light, at room temperature, and at 500 r / min, 3-(methacryloyloxy)propyltrimethoxysilane is added dropwise uniformly over 35 min. After the addition is completed, the temperature is raised to 35°C, and the reaction is carried out at 500 r / min for 38 h. The solvent and unreacted 3-(methacryloyloxy)propyltrimethoxysilane are removed by vacuum distillation. The mixture is then dried under vacuum at 65°C for 11 h to obtain the heavy oil anti-salt viscosity reducer. The remaining steps are the same as in Example 2. The grafting rate of 3-(methacryloyloxy)propyltrimethoxysilane is 47.68%.

[0042] Comparative Example 2: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 2 differs from that in Example 2 in that steps (1) and (2) are omitted, and third-generation polyamide-amine is used directly as the heavy oil anti-salt viscosity reducer. The remaining steps are the same as in Example 2.

[0043] Comparative Example 3: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 3 differs from that in Example 2 in that it uses a different dendritic polyamide-amine; a first-generation polyamide-amine is used instead of a third-generation polyamide-amine. The remaining steps are the same as in Example 2. The grafting rate of the modified silane coupling agent is 48.51%.

[0044] Comparative Example 4: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 4 differs from that in Example 2 in that it uses a different dendritic polyamide-amine; a fifth-generation polyamide-amine is used instead of a third-generation polyamide-amine. The remaining steps are the same as in Example 2. The grafting rate of the modified silane coupling agent is 42.43%.

[0045] Comparative Example 5: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 5 differs from that in Example 2 in step (2). Step (2) is modified as follows: the molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:8, and the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:36. The dendritic polyamide-amine is first dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, protected from light, at room temperature, and at 500 r / min, the modified silane coupling agent is uniformly added dropwise over 35 min. After the addition is complete, the temperature is raised to 35°C, and the reaction is carried out at 500 r / min for 38 h. The solvent and unreacted modified silane coupling agent are removed by vacuum distillation, and the mixture is vacuum dried at 65°C for 11 h to obtain the heavy oil anti-salt viscosity reducer. The remaining steps are the same as in Example 2. The grafting rate of the modified silane coupling agent is 11.57%.

[0046] Comparative Example 6: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 6 differs from that in Example 2 in step (2). Step (2) is modified as follows: the molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:4, and the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:18. The dendritic polyamide-amine is first dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, protected from light, at room temperature, and at 500 r / min, the modified silane coupling agent is uniformly added dropwise over 35 min. After the addition is complete, the temperature is raised to 35°C, and the reaction is carried out at 500 r / min for 38 h. The solvent and unreacted modified silane coupling agent are removed by vacuum distillation, and the mixture is vacuum dried at 65°C for 11 h to obtain the heavy oil anti-salt viscosity reducer. The remaining steps are the same as in Example 2. The grafting rate of the modified silane coupling agent is 22.84%.

[0047] Comparative Example 7: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 7 differs from that in Example 2 in step (2). Step (2) is modified as follows: the molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:1.4, and the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:9. The dendritic polyamide-amine is first dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, protected from light, at room temperature, and at 500 r / min, the modified silane coupling agent is uniformly added dropwise over 35 min. After the addition is complete, the temperature is raised to 35°C, and the reaction is carried out at 500 r / min for 38 h. The solvent and unreacted modified silane coupling agent are removed by vacuum distillation, and the mixture is vacuum dried at 65°C for 11 h to obtain the heavy oil anti-salt viscosity reducer. The remaining steps are the same as in Example 2. The grafting rate of the modified silane coupling agent is 63.82%.

[0048] Comparative Example 8: The preparation method of the heavy oil anti-salt viscosity reducer in Comparative Example 8 differs from that in Example 2 in step (2). Step (2) is modified as follows: the molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:1, and the mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:9. The dendritic polyamide-amine is first dissolved in N,N-dimethylformamide. Under a nitrogen atmosphere, in the dark, at room temperature, at 500 r / min, the modified silane coupling agent is uniformly added dropwise over 35 min. After the addition is complete, the temperature is raised to 35°C, and the reaction is carried out at 500 r / min for 38 h. The solvent and unreacted modified silane coupling agent are removed by vacuum distillation, and the mixture is vacuum dried at 65°C for 11 h to obtain the heavy oil anti-salt viscosity reducer. The remaining steps are the same as in Example 2. The grafting rate of the modified silane coupling agent is 85.26%.

[0049] Test Example 1: Salt resistance and viscosity reduction performance test: The viscosity reduction rate of the prepared heavy oil salt-resistant viscosity reducer on heavy oil and its viscosity reduction rate in a high salinity environment are tested to evaluate its viscosity reduction performance and salt resistance performance. The specific test methods are as follows: Heavy oil: The heavy oil used comes from the Tarim Oilfield, and its viscosity at 50℃ is 5.6 × 10⁻⁶. 4 The content of asphaltene was 38.9 wt%, and the acid value was 0.79 mg (KOH) / g; Sample aqueous solution: The heavy oil anti-salt viscosity reducer prepared in each example and comparative example was first prepared into an aqueous solution at a concentration of 10 mg / ml. The water used was deionized water. Then it was diluted to a viscosity reducer solution of 1000 mg / L. The viscosity reducer solution was mixed with heavy oil at an oil-water ratio of 6:4 at 50°C and stirred at 250 r / min for 2 min to prepare the sample aqueous solution. Viscosity reduction performance test: The viscosity of the sample aqueous solution was measured using a DV-II+PRO rotational viscometer, with a shear rate of 7.48 s. -1The test temperature was 50℃, and the viscosity reduction rate was calculated using the following formula: VRR(%)=(μ0-μ e )÷μ0×100%; In the formula, μ0 represents the initial viscosity of heavy oil, μ e The viscosity of the sample aqueous solution is represented by VRR (%), which is the viscosity reduction rate. Each group of samples was tested in parallel 5 times, and the average value was recorded. Salt tolerance test: Mineralized water with a mineralization of 85000 mg / L was prepared by mixing 5.5% sodium chloride, 2.0% potassium chloride, 0.45% magnesium chloride, and 0.55% calcium chloride. The sample aqueous solution was prepared by replacing deionized water with mineralized water. The viscosity reduction rate in the mineralized water environment was tested according to the viscosity reduction performance test procedure. Each group of samples was tested in parallel 5 times, and the average value was recorded.

[0050] The results are shown in Table 1: Table 1 Example 1 98.2% 96.4% Example 2 98.5% 96.9% Example 3 98.3% 96.2% Example 4 97.1% 95.4% Comparative Example 1 71.5% 43.1% Comparative Example 2 10.8% 8.4% Comparative Example 3 73.3% 62.1% Comparative Example 4 92.4% 89.6% Comparative Example 5 28.3% 22.5% Comparative Example 6 63.7% 49.5% Comparative Example 7 86.4% 84.3% Comparative Example 8 71.2% 67.5% A comparison of the experimental data from Examples 1-4 and Comparative Examples 1-8 in Table 1 reveals that the heavy oil anti-salt viscosity reducer prepared in this invention has good salt resistance and viscosity reduction properties.

[0051] By comparing the data in the table, the data in Comparative Example 1 shows that the -OCH3 group in the unmodified 3-(methacryloyloxy)propyltrimethoxysilane is easily hydrolyzed, and is prone to cross-linking and polymerization during use, leading to flocculation failure and decreased viscosity reduction performance. At the same time, the presence of a high-salt environment promotes the occurrence of hydrolysis and condensation, which further reduces the viscosity reduction effect.

[0052] By comparing the data in the table, the data in Comparative Example 2 shows that ungrafted, simple dendritic polyamide-amine has almost no viscosity-reducing effect, and the viscosity-reducing effect is very poor.

[0053] The data comparison in the table shows that when the first-generation polyamide-amine is used as a substitute, the resulting heavy oil anti-salt viscosity reducer molecules are smaller, the interfacial coverage density is lower, and the viscosity reduction performance is poor. However, when the fifth-generation polyamide-amine is used as a substitute, although the viscosity reduction effect is only slightly lower, the synthesis is more difficult, the marginal benefit is lower, and the viscosity reduction performance actually decreases.

[0054] By comparing the data in the table, the data from Comparative Examples 5 to 8 show that the grafting rate of the modified silane coupling agent needs to be controlled within a suitable range to achieve good viscosity reduction and salt resistance. When the grafting rate is too low, there is insufficient lipophilic end, weak interfacial activity, and poor viscosity reduction performance. When the grafting rate is too high, firstly, there is an increase in unreacted modified silane coupling agent, resulting in serious waste of raw materials. Moreover, the excessively high grafting rate leads to a decrease in hydrophilicity, weakened surface activity, poor viscosity reduction effect, and poor emulsification viscosity reduction performance.

[0055] Test Example 2: Grafting rate test: The content of primary amines in dendritic polyamide-amine and heavy oil anti-salt viscosity reducer was tested by acid-base titration. The grafting rate was calculated by the ratio of the contents of the two. Each group was tested in parallel for 5 times and the average value was recorded.

[0056] The results are as described above.

[0057] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The application of a heavy oil anti-salt viscosity reducer in petroleum extraction, characterized in that, The heavy oil anti-salt viscosity reducer is prepared by grafting a modified silane coupling agent with a dendritic polyamide-amine. The structural formula of the modified silane coupling agent is as follows: ； The grafting rate of the modified silane coupling agent is 40%~50%; The dendritic polyamide-amine is obtained by alternating reactions of ethylenediamine and methyl acrylate with ethylenediamine as the core. The dendritic polyamide-amine is a second-generation polyamide-amine or a third-generation polyamide-amine.

2. The application of a heavy oil anti-salt viscosity reducer according to claim 1 in petroleum extraction, characterized in that, The modified silane coupling agent is prepared by reacting 3-(methacryloyloxy)propyltrimethoxysilane with trimethylchlorosilane.

3. The application of a heavy oil anti-salt viscosity reducer according to any one of claims 1 to 2 in petroleum extraction, characterized in that, The preparation of the heavy oil anti-salt viscosity reducer includes the following steps: Dendritic polyamide-amine was dissolved in N,N-dimethylformamide. Modified silane coupling agent was added dropwise under a nitrogen atmosphere, protected from light, and at room temperature. After the addition was complete, the temperature was raised to 30-35℃ and reacted for 36-40 hours. The solvent and unreacted modified silane coupling agent were removed by vacuum distillation, and the mixture was dried to obtain a heavy oil anti-salt viscosity reducer.

4. The application of a heavy oil anti-salt viscosity reducer according to claim 3 in petroleum extraction, characterized in that, The molar ratio of the modified silane coupling agent to the primary amino group in the dendritic polyamide-amine is 1:(1.8~2.2).

5. The application of a heavy oil anti-salt viscosity reducer according to claim 3 in petroleum extraction, characterized in that, The mass ratio of the modified silane coupling agent to N,N-dimethylformamide is 1:(8~10).

6. The application of a heavy oil anti-salt viscosity reducer according to claim 3 in petroleum extraction, characterized in that, The preparation method of the modified silane coupling agent includes the following preparation steps: First, 3-(methacryloyloxy)propyltrimethoxysilane and trimethylchlorosilane were mixed evenly. At room temperature, a mixture of water and methanol was added dropwise, controlling the dropping rate to ensure that the system temperature was below 50°C. After the addition was complete, the mixture was stirred and refluxed at room temperature for 16-20 hours. The organic layer was separated by standing, washed with water until neutral, and water and methanol were removed. The fraction at 120-124°C under 3 mmHg was collected by distillation to obtain the modified silane coupling agent.

7. The application of a heavy oil anti-salt viscosity reducer according to claim 6 in oil extraction, characterized in that, The molar ratio of 3-(methacryloyloxy)propyltrimethoxysilane, trimethylchlorosilane, methanol, and water is 1:(6~9):(6~9):(9~13.5).

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