Preparation method and application of polymer-based heavy oil low-temperature demulsifier

Abstract

The present invention relates to a preparation method and application of a polymer-based heavy oil low-temperature demulsifier, and belongs to the technical field of petroleum processing. The preparation method of the polymer-based heavy oil low-temperature demulsifier disclosed in the present invention comprises the following steps: (1) preheating resorcinol, mixing it with a sulfuric acid solution and keeping it warm, then adding formaldehyde and stirring to form a mixture; (2) cooling the mixture to room temperature, adding distilled water, and then adding sodium hydroxide to adjust the pH value to form a mixed solution; (3) adding an acyl chloride compound to the mixed solution and heating it, then passing ammonia gas to keep it warm, cooling it to room temperature and letting it stand for stratification, taking the lower layer and vacuum distilling to obtain a modified phenolic resin; (4) reacting the modified phenolic resin with an epoxy compound to obtain a demulsifier. The present invention obtains a modified phenolic resin by introducing a highly polar sulfonic acid group and an amide group, so that it is fully dispersed in an emulsion, replacing the natural active substance so that the interfacial film strength of the emulsion is reduced, thereby showing good demulsification performance.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum processing and relates to a preparation method and application of a polymer-based heavy oil low-temperature demulsifier. Background Art

[0002] The water content in crude oil emulsion will increase the load on pipelines and storage tanks, and will also cause corrosion and scaling of metals. There are many methods for dehydrating crude oil, among which the addition of chemical demulsifiers is a fast and common method to achieve oil-water two-phase separation. At present, the most widely used demulsifiers in oil fields are multi-branched polyether demulsifiers or their compound modified products. Under severe weather conditions, the oil-water interface of the primary separator of the offshore platform will be unstable, the oil-water interface will drop rapidly, and the oil-water separation effect will deteriorate. In order to improve the oil-water separation effect on site, it is necessary to study the demulsifier formula suitable for low temperatures. In addition, the most direct and effective measure to reduce the energy consumption of dehydration is to reduce the dehydration temperature.

[0003] The lowering of dehydration temperature will increase the viscosity of crude oil emulsion, and the crude oil demulsifier will be difficult to disperse in crude oil, and the migration speed of crude oil demulsifier from oil phase to oil-water interface film will be slowed down. At the same time, when the dehydration temperature becomes lower, the paraffin originally dissolved in the paraffin-based crude oil will gradually crystallize out from the crude oil when it is lower than the wax precipitation temperature of crude oil, which will affect the diffusion of crude oil demulsifier in crude oil and the displacement and replacement on the oil-water interface film, thereby affecting the rupture of the interface film of crude oil emulsion. Therefore, the preparation method of a polymer-based heavy oil low-temperature demulsifier provided by the present invention can effectively solve the above problems. Summary of the invention

[0004] The present invention relates to a preparation method and application of a polymer-based heavy oil low-temperature demulsifier, and belongs to the technical field of petroleum processing. The preparation method of the polymer-based heavy oil low-temperature demulsifier disclosed in the present invention comprises the following steps: (1) preheating resorcinol, mixing it with a sulfuric acid solution and keeping it warm, then adding formaldehyde and stirring to form a mixture; (2) cooling the mixture to room temperature, adding distilled water, and then adding sodium hydroxide to adjust the pH value to form a mixed solution; (3) adding an acyl chloride compound to the mixed solution and heating it, then passing ammonia gas to keep it warm, cooling it to room temperature and standing it for stratification, taking the lower layer and vacuum distilling it to obtain a modified phenolic resin; (4) reacting the modified phenolic resin with an epoxy compound to obtain a demulsifier. The present invention obtains a modified phenolic resin by introducing a highly polar sulfonic acid group and an amide group, so that it is fully dispersed in an emulsion, replacing the natural active substance so that the interfacial film strength of the emulsion is reduced, thereby showing good demulsification performance.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a polymer-based heavy oil low-temperature demulsifier, the method comprising the following steps:

[0007] (1) preheating resorcinol and mixing it with a sulfuric acid solution and keeping the temperature, and then adding formaldehyde and stirring to form a mixture;

[0008] (2) the mixture is cooled to room temperature, distilled water is added, and then sodium hydroxide is added to adjust the pH value to form a mixed solution;

[0009] (3) adding an acyl chloride compound to the mixed solution and heating it, then introducing ammonia gas to keep the mixture warm, cooling it to room temperature and allowing it to stand for stratification, and removing the lower layer and distilling it under reduced pressure to obtain a modified phenolic resin;

[0010] (4) the modified phenolic resin is mixed with a potassium hydroxide solution, nitrogen is introduced, the temperature is increased, and propylene oxide is subsequently added to form an intermediate;

[0011] (5) The intermediate is placed in a reactor and heated, ethylene oxide is introduced, glacial acetic acid is added and mixed, and then cooled to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier.

[0012] Furthermore, the preheating temperature in step (1) is 40-46° C., and the mass ratio of resorcinol, sulfuric acid solution and formaldehyde is 1:1-1.4:0.7.

[0013] Furthermore, in the step (1), the mass fraction of the sulfuric acid solution is 80-85%, and the insulation time is 2-3 hours.

[0014] Furthermore, in the step (2), the mass ratio of the mixture to distilled water is 1:10-20, and the pH value is 10-12.

[0015] Furthermore, in step (3), the volume ratio of the mixed solution to the acyl chloride compound is 10:2-3, wherein the acyl chloride compound is composed of benzoyl chloride and n-butyryl chloride in a mass ratio of 1:1, and the mass ratio of ammonia to the acyl chloride compound is 1:1.

[0016] Furthermore, the heating temperature in step (3) is 90-100° C., the ammonia gas is kept warm for 10-20 min, and the pressure and temperature of the reduced pressure distillation are 0.03 MPa and 75-95° C., respectively.

[0017] Furthermore, in step (4), the mass ratio of the modified phenolic resin to the potassium hydroxide solution is 100:0.5-1, wherein the mass fraction of the potassium hydroxide solution is 30-40%.

[0018] Furthermore, the heating temperature in step (4) is 100-110° C., and the mass ratio of the modified phenolic resin to propylene oxide is 1:2.

[0019] Furthermore, the heating in step (5) refers to heating to 120-130° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

[0020] Furthermore, the polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

[0021] Beneficial effects of the present invention:

[0022] The invention obtains the modified phenolic resin by introducing high-polarity sulfonic acid groups and amide groups, and benzoyl chloride and n-butyryl chloride are respectively connected to two phenolic hydroxyl positions, and ammonia gas is introduced to replace chlorine atoms to make them acylated; the demulsifier composed of the high-polarity sulfonic acid groups and amide groups and the hydrophobic benzene rings reaches a hydrophilic-lipophilic balance in the W / O or O / W emulsion, so that the demulsifier is fully dispersed in the emulsion and has a strong adsorption capacity on the oil-water interface of the emulsion, and replaces the natural active substances so that the interfacial film strength of the emulsion is reduced, thereby showing good demulsification performance. DETAILED DESCRIPTION

[0023] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with embodiments.

[0024] Example 1

[0025] A method for preparing a polymer-based heavy oil low-temperature demulsifier, the method comprising the following steps:

[0026] (1) preheating resorcinol and mixing it with a sulfuric acid solution and keeping the temperature, and then adding formaldehyde and stirring to form a mixture;

[0027] (2) cooling the mixture to room temperature, adding distilled water, and then adding sodium hydroxide to adjust the pH value to form a mixed solution;

[0028] (3) adding an acyl chloride compound to the mixed solution and heating it, then introducing ammonia gas to keep the mixture warm, cooling it to room temperature and allowing it to stand for stratification, and removing the lower layer and distilling it under reduced pressure to obtain a modified phenolic resin;

[0029] (4) the modified phenolic resin is mixed with a potassium hydroxide solution, nitrogen is introduced at the same time, the temperature is increased, and propylene oxide is subsequently added to form an intermediate;

[0030] (5) The intermediate is placed in a reactor and heated, ethylene oxide is introduced, glacial acetic acid is added and mixed, and then cooled to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier.

[0031] The preheating temperature in step (1) is 40° C., and the mass ratio of resorcinol, sulfuric acid solution and formaldehyde is 1:1:0.7.

[0032] The mass fraction of the sulfuric acid solution in step (1) is 80%, and the insulation time is 2 hours.

[0033] The mass ratio of the mixture to distilled water in the step (2) is 1:10, and the pH value is 10.

[0034] In the step (3), the volume ratio of the mixed solution to the acyl chloride compound is 10:2, wherein the acyl chloride compound is composed of benzoyl chloride and n-butyryl chloride in a mass ratio of 1:1, and the mass ratio of ammonia to the acyl chloride compound is 1:1.

[0035] The heating temperature in step (3) is 90° C., the ammonia gas is kept warm for 10 min, and the pressure and temperature of the reduced pressure distillation are 0.03 MPa and 85° C., respectively.

[0036] In the step (4), the mass ratio of the modified phenolic resin to the potassium hydroxide solution is 100:0.5, wherein the mass fraction of the potassium hydroxide solution is 30%.

[0037] The heating temperature in the step (4) is 100° C., and the mass ratio of the modified phenolic resin to propylene oxide is 1:2.

[0038] The heating in step (5) refers to heating to 120° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

[0039] The polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

[0040] Example 2

[0041] A method for preparing a polymer-based heavy oil low-temperature demulsifier, the method comprising the following steps:

[0042] (1) preheating resorcinol and mixing it with a sulfuric acid solution and keeping the temperature, and then adding formaldehyde and stirring to form a mixture;

[0043] (2) the mixture is cooled to room temperature, distilled water is added, and then sodium hydroxide is added to adjust the pH value to form a mixed solution;

[0044] (3) adding an acyl chloride compound to the mixed solution and heating it, then introducing ammonia gas to keep the mixture warm, cooling it to room temperature and allowing it to stand for stratification, and removing the lower layer and distilling it under reduced pressure to obtain a modified phenolic resin;

[0045] (4) the modified phenolic resin is mixed with a potassium hydroxide solution, nitrogen is introduced, the temperature is increased, and propylene oxide is subsequently added to form an intermediate;

[0046] (5) The intermediate is placed in a reactor and heated, ethylene oxide is introduced, glacial acetic acid is added and mixed, and then cooled to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier.

[0047] The preheating temperature in step (1) is 43° C., and the mass ratio of resorcinol, sulfuric acid solution and formaldehyde is 1:1.2:0.7.

[0048] The mass fraction of the sulfuric acid solution in step (1) is 82%, and the insulation time is 2.5 hours.

[0049] The mass ratio of the mixture to distilled water in the step (2) is 1:15, and the pH value is 11.

[0050] In the step (3), the volume ratio of the mixed solution to the acyl chloride compound is 10:2.5, wherein the acyl chloride compound is composed of benzoyl chloride and n-butyryl chloride in a mass ratio of 1:1, and the mass ratio of ammonia to the acyl chloride compound is 1:1.

[0051] The heating temperature in step (3) is 95° C., the ammonia gas is kept warm for 15 min, and the pressure and temperature of the reduced pressure distillation are 0.03 MPa and 85° C., respectively.

[0052] In the step (4), the mass ratio of the modified phenolic resin to the potassium hydroxide solution is 100:0.8, wherein the mass fraction of the potassium hydroxide solution is 35%.

[0053] The heating temperature in step (4) is 105° C., and the mass ratio of the modified phenolic resin to propylene oxide is 1:2.

[0054] The heating in step (5) refers to heating to 125° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

[0055] The polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

[0056] Example 3

[0057] A method for preparing a polymer-based heavy oil low-temperature demulsifier, the method comprising the following steps:

[0058] (1) preheating resorcinol and mixing it with a sulfuric acid solution and keeping the temperature, and then adding formaldehyde and stirring to form a mixture;

[0059] (2) cooling the mixture to room temperature, adding distilled water, and then adding sodium hydroxide to adjust the pH value to form a mixed solution;

[0060] (3) adding an acyl chloride compound to the mixed solution and heating it, then introducing ammonia gas to keep the mixture warm, cooling it to room temperature and allowing it to stand for stratification, and removing the lower layer and distilling it under reduced pressure to obtain a modified phenolic resin;

[0061] (4) the modified phenolic resin is mixed with a potassium hydroxide solution, nitrogen is introduced at the same time, the temperature is increased, and propylene oxide is subsequently added to form an intermediate;

[0062] (5) The intermediate is placed in a reactor and heated, ethylene oxide is introduced, glacial acetic acid is added and mixed, and then cooled to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier.

[0063] The preheating temperature in step (1) is 46° C., and the mass ratio of resorcinol, sulfuric acid solution and formaldehyde is 1:1.4:0.7.

[0064] The mass fraction of the sulfuric acid solution in step (1) is 85%, and the insulation time is 3 hours.

[0065] The mass ratio of the mixture to distilled water in the step (2) is 1:20, and the pH value is 12.

[0066] In the step (3), the volume ratio of the mixed solution to the acyl chloride compound is 10:3, wherein the acyl chloride compound is composed of benzoyl chloride and n-butyryl chloride in a mass ratio of 1:1, and the mass ratio of ammonia to the acyl chloride compound is 1:1.

[0067] The heating temperature in step (3) is 100° C., the ammonia gas is kept warm for 20 min, and the pressure and temperature of the reduced pressure distillation are 0.03 MPa and 85° C., respectively.

[0068] In the step (4), the mass ratio of the modified phenolic resin to the potassium hydroxide solution is 100:1, wherein the mass fraction of the potassium hydroxide solution is 40%.

[0069] The heating temperature in step (4) is 110° C., and the mass ratio of the modified phenolic resin to propylene oxide is 1:2.

[0070] The heating in step (5) refers to heating to 130° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

[0071] The polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

[0072] Comparative Example 1

[0073] On the basis of Example 3, a method for preparing a polymer-based heavy oil low-temperature demulsifier is provided, wherein the method for preparing the polymer-based heavy oil low-temperature demulsifier comprises the following steps:

[0074] (1) Phenolic resin is mixed with potassium hydroxide solution, nitrogen is introduced, and then the temperature is increased, and then propylene oxide is added to form an intermediate;

[0075] (2) The intermediate is placed in a reactor and heated, ethylene oxide is introduced, glacial acetic acid is added and mixed, and then cooled to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier.

[0076] In the step (4), the mass ratio of the phenolic resin to the potassium hydroxide solution is 100:1, wherein the mass fraction of the potassium hydroxide solution is 40%.

[0077] The heating temperature in step (4) is 110° C., and the mass ratio of the phenolic resin to propylene oxide is 1:2.

[0078] The heating in step (5) refers to heating to 130° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

[0079] The polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

[0080] The phenolic resin is purchased from: phenolic resin / Dahui-9003-35-4.

[0081] Comparative Example 2

[0082] On the basis of Example 3, a method for preparing a polymer-based heavy oil low-temperature demulsifier is provided, wherein the method for preparing the polymer-based heavy oil low-temperature demulsifier comprises the following steps:

[0083] (1) preheating resorcinol and mixing it with a sulfuric acid solution and keeping the temperature, and then adding formaldehyde and stirring to form a mixture;

[0084] (2) the mixture is cooled to room temperature, distilled water is added, and then sodium hydroxide is added to adjust the pH value to form a mixed solution;

[0085] (3) adding an acyl chloride compound to the mixed solution and heating it, then introducing ammonia gas to keep the mixture warm, cooling it to room temperature and allowing it to stand for stratification, and removing the lower layer and distilling it under reduced pressure to obtain a modified phenolic resin;

[0086] (4) the modified phenolic resin is mixed with a potassium hydroxide solution, nitrogen is introduced, the temperature is increased, and propylene oxide is subsequently added to form an intermediate;

[0087] (5) The intermediate is placed in a reactor and heated, ethylene oxide is introduced, glacial acetic acid is added and mixed, and then cooled to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier.

[0088] The preheating temperature in step (1) is 46° C., and the mass ratio of resorcinol, sulfuric acid solution and formaldehyde is 1:1.4:0.7.

[0089] The mass fraction of the sulfuric acid solution in step (1) is 85%, and the insulation time is 3 hours.

[0090] The mass ratio of the mixture to distilled water in the step (2) is 1:20, and the pH value is 12.

[0091] In the step (3), the volume ratio of the mixed liquid to the acyl chloride compound is 10:3, wherein the acyl chloride compound is benzoyl chloride, and the mass ratio of the ammonia gas to the acyl chloride compound is 1:1.

[0092] The heating temperature in step (3) is 100° C., the ammonia gas is kept warm for 20 min, and the pressure and temperature of the reduced pressure distillation are 0.03 MPa and 85° C., respectively.

[0093] In the step (4), the mass ratio of the modified phenolic resin to the potassium hydroxide solution is 100:1, wherein the mass fraction of the potassium hydroxide solution is 40%.

[0094] The heating temperature in step (4) is 110° C., and the mass ratio of the modified phenolic resin to propylene oxide is 1:2.

[0095] The heating in step (5) refers to heating to 130° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

[0096] The polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

[0097] Comparative Example 3

[0098] On the basis of Example 3, a method for preparing a polymer-based heavy oil low-temperature demulsifier is provided, wherein the method for preparing the polymer-based heavy oil low-temperature demulsifier comprises the following steps:

[0099] (1) preheating resorcinol and mixing it with a sulfuric acid solution and keeping the temperature, and then adding formaldehyde and stirring to form a mixture;

[0100] (2) cooling the mixture to room temperature, adding distilled water, and then adding sodium hydroxide to adjust the pH value to form a mixed solution;

[0101] (3) adding an acyl chloride compound to the mixed solution and heating it, then introducing ammonia gas to keep the mixture warm, cooling it to room temperature and allowing it to stand for stratification, and removing the lower layer and distilling it under reduced pressure to obtain a modified phenolic resin;

[0102] (4) the modified phenolic resin is mixed with a potassium hydroxide solution, nitrogen is introduced, the temperature is increased, and propylene oxide is subsequently added to form an intermediate;

[0103] (5) The intermediate is placed in a reactor and heated, ethylene oxide is introduced, glacial acetic acid is added and mixed, and then cooled to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier.

[0104] The preheating temperature in step (1) is 46° C., and the mass ratio of resorcinol, sulfuric acid solution and formaldehyde is 1:1.4:0.7.

[0105] The mass fraction of the sulfuric acid solution in step (1) is 85%, and the insulation time is 3 hours.

[0106] The mass ratio of the mixture to distilled water in the step (2) is 1:20, and the pH value is 12.

[0107] In the step (3), the volume ratio of the mixed solution to the acyl chloride compound is 10:3, wherein the acyl chloride compound is n-butyryl chloride, and the mass ratio of the ammonia gas to the acyl chloride compound is 1:1.

[0108] The heating temperature in step (3) is 100° C., the ammonia gas is kept warm for 20 min, and the pressure and temperature of the reduced pressure distillation are 0.03 MPa and 85° C., respectively.

[0109] In the step (4), the mass ratio of the modified phenolic resin to the potassium hydroxide solution is 100:1, wherein the mass fraction of the potassium hydroxide solution is 40%.

[0110] The heating temperature in step (4) is 110° C., and the mass ratio of the modified phenolic resin to propylene oxide is 1:2.

[0111] The heating in step (5) refers to heating to 130° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

[0112] The polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

[0113] 1. Performance Testing

[0114] According to SY-T 5281-2000 "Method for evaluating the performance of crude oil demulsifiers (bottle test method), Examples 1-3 and Comparative Examples 1-3 were used as samples to test the demulsifier performance. Specifically, open the constant temperature water bath and place the crude oil in a 40°C water bath until the crude oil emulsion is in a fluid state, and then introduce the emulsion into a 100mL colorimetric tube. Wipe the residual crude oil on the colorimetric tube with oil-absorbing paper, immerse the entire colorimetric tube in a 40°C constant temperature water bath and preheat for 20 minutes. After preheating, add 120 mg / L of demulsifier with an injection needle, plug the lid, and shake manually for 3 minutes, at least 100 times (open the lid during shaking to release the gas in the tube to prevent the bottle cap from rushing out), and mix the demulsifier with the crude oil emulsion. Place the mixed emulsion vertically in a water bath to start the demulsification experiment. Set the time to 25min, 35min, and 45min, record the dehydration amount, and calculate the demulsification rate. The calculation formula for the demulsification rate is as follows:

[0115] , the above test results are shown in Table 1.

[0116] Table 1 Test results

[0117]

[0118] As can be seen from Table 1, the demulsification rates of Examples 1-3 at 25min, 35min and 45min are all greater than those of Comparative Examples 1-3, and the demulsification rates at 45min are all above 95%. In Comparative Example 1, the phenolic resin does not introduce high polar groups, and its dispersibility in the emulsion is poor, so the demulsification rate is significantly reduced; Comparative Examples 2-3 use benzoyl chloride or n-butyryl chloride for acylation, and when only benzoyl chloride is added, the molecular steric hindrance increases, which is not conducive to the dispersion of the demulsifier in the emulsion, and when only n-butyryl chloride is added, the hydrophilic-lipophilic balance of the demulsifier in the emulsion is broken, which is not conducive to replacing the natural active substance, so that the interfacial film strength of the emulsion is reduced, and therefore the demulsification rate is worse than that of the embodiment.

[0119] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a polymer-based heavy oil low-temperature demulsifier, characterized in that: The preparation method comprises the following steps: (1) preheating resorcinol and mixing it with a sulfuric acid solution and keeping the mixture warm, then adding formaldehyde and stirring to form a mixture; the mass ratio of the resorcinol, the sulfuric acid solution and the formaldehyde is 1:1-1.4:0.7; and the mass fraction of the sulfuric acid solution is 80-85%; (2) cooling the mixture to room temperature, adding distilled water, and then adding sodium hydroxide to adjust the pH value to form a mixed solution; (3) adding an acyl chloride compound to the mixed solution and heating it, then introducing ammonia gas to keep the mixture warm, cooling it to room temperature and allowing it to stand for stratification, and removing the lower layer and distilling it under reduced pressure to obtain a modified phenolic resin; (4) the modified phenolic resin is mixed with a potassium hydroxide solution, nitrogen is introduced at the same time, the temperature is increased, and propylene oxide is subsequently added to form an intermediate; (5) taking the intermediate and placing it in a reaction kettle to raise the temperature, introducing ethylene oxide, adding glacial acetic acid and mixing, and then cooling to room temperature to obtain a polymer-based heavy oil low-temperature demulsifier; In the step (3), the volume ratio of the mixed solution to the acyl chloride compound is 10:2-3, wherein the acyl chloride compound is composed of benzoyl chloride and n-butyryl chloride in a mass ratio of 1:1, and the mass ratio of ammonia to the acyl chloride compound is 1:1; In step (2), the mass ratio of the mixture to distilled water is 1:10-20, and the pH value is 10-12; The heating temperature in step (3) is 90-100° C., and the ammonia gas is kept warm for 10-20 minutes; In the step (4), the mass ratio of the modified phenolic resin to the potassium hydroxide solution is 100:0.5-1, wherein the mass fraction of the potassium hydroxide solution is 30-40%; The heating temperature in step (4) is 100-110° C., and the mass ratio of the modified phenolic resin to propylene oxide is 1:2; The heating in step (5) refers to heating to 120-130° C., the amount of ethylene oxide introduced is equal to the mass of propylene oxide in step (4), and the amount of glacial acetic acid added accounts for 0.02% of the mass of the intermediate.

2. The method for preparing a polymer-based heavy oil low-temperature demulsifier according to claim 1, characterized in that: The preheating temperature in step (1) is 40-46°C.

3. The method for preparing a polymer-based heavy oil low-temperature demulsifier according to claim 1, characterized in that: In the step (1), the insulation time is 2-3 hours.

4. The method for preparing a polymer-based heavy oil low-temperature demulsifier according to claim 1, characterized in that: In the step (3), the pressure and temperature of the reduced pressure distillation are 0.03 MPa and 75-95° C., respectively.

5. The method for preparing a polymer-based heavy oil low-temperature demulsifier according to claim 1, characterized in that: The polymer-based heavy oil low-temperature demulsifier is used in the field of petroleum processing.

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