Comb copolymer demulsifier and its preparation method and application

Abstract

The present invention discloses a comb copolymer demulsifier and its preparation method and application. The comb copolymer demulsifier is a polymer comprising repeating units as shown in formula I, #imgabs0# wherein x is an integer of 1 to 5, R is C3 to C 18 The comb copolymer demulsifier has the advantages of low demulsification temperature, short demulsification time, high demulsification efficiency, etc. It is suitable for a wide pH range and has high salt tolerance. The preparation process is simple and the method is easy to implement.

Description

Technical Field

[0001] The present invention relates to the technical field of crude oil processing, in particular to a comb copolymer demulsifier and a preparation method and application thereof. Background Art

[0002] With the development of tertiary oil recovery (TER) technologies in the oil and gas industry, a series of enhanced oil recovery methods, such as thermal flooding, miscible flooding, chemical flooding, and microbial flooding, have been widely applied in practical production. However, the use of these technologies inevitably produces large amounts of oil-water emulsions. Factors influencing the formation and stability of emulsions include low interfacial tension, the formation of an oil-water interfacial film, the formation of a diffuse double layer, the adsorption of solid particles, temperature, emulsion pH, and salinity. The presence of oil-water emulsions not only reduces pipeline service life and increases storage and transportation risks, but can also cause severe corrosion of production equipment during crude oil production. Therefore, demulsification of oil-water emulsions is of paramount importance.

[0003] Chemical demulsification has attracted widespread attention in the petroleum industry due to its high efficiency and low production volume. Traditional demulsifiers primarily use ethylene oxide and propylene oxide as raw materials. For example, Chinese patent application CN 115558096A discloses a comb-shaped cardanol polyether demulsifier, which is produced by block polymerization of cardanol with ethylene oxide and propylene oxide under the action of an alkaline catalyst.

[0004] Although the demulsifier obtained by the above scheme has a high dehydration rate, it has problems such as high demulsification temperature and complex synthesis process. The demulsifier is not universal and cannot achieve demulsification under acidic, alkaline and high salinity conditions, and will cause secondary pollution and harm the environment. Summary of the Invention

[0005] In view of this, the present application provides a comb copolymer demulsifier and a preparation method and application thereof, which has high demulsification efficiency and strong adaptability.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions:

[0007] In the first aspect, a comb copolymer demulsifier is a polymer comprising repeating units as shown in formula I,

[0008]

[0009] Wherein, x is selected from an integer of 1-5, and R is selected from C3-C 18 alkyl.

[0010] In a second aspect, the present application provides a method for preparing a comb-like copolymer demulsifier, comprising the following steps: using primary amine and diglycidyl ether compounds as raw materials, conducting a ring-opening polymerization reaction to obtain a comb-like copolymer demulsifier, wherein the molar ratio of the primary amine to the diglycidyl ether compound is 1:1.

[0011] Preferably, the diglycidyl ether compound includes one or more of ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, and pentaethylene glycol diglycidyl ether.

[0012] Preferably, the primary amine is R-NH2, wherein R is selected from C3-C 18 alkyl.

[0013] Preferably, the temperature of the ring-opening polymerization reaction is 60-150° C., and the reaction time is 6-12 h.

[0014] Preferably, the primary amine is dodecylamine.

[0015] Preferably, the diglycidyl ether compound is diethylene glycol diglycidyl ether.

[0016] Preferably, the ring-opening polymerization reaction is carried out under the protection of an inert gas.

[0017] In a third aspect, the present application provides an application of a comb copolymer demulsifier in demulsifying crude oil emulsions.

[0018] Preferably, the demulsification temperature is 40-70°C.

[0019] The beneficial effects of the present application are as follows: The present application adopts primary amine and polyethylene glycol diglycidyl ether as reaction raw materials, which not only ensures the safety of the synthesis, but also reduces the cost of raw materials. The obtained comb-like alternating copolymer demulsifier has the ability to greatly reduce interfacial tension and destroy the original interfacial film, and can effectively promote the demulsification process. The prepared comb-like alternating copolymer demulsifier can bridge adjacent droplets in the emulsion, destroy the interfacial film formed by the original natural surfactant on the surface of the droplets, and form an unstable and easily destructible composite interfacial film. The comb-like alternating copolymer demulsifier of the present invention has the characteristics of simple preparation method, low demulsification temperature, short demulsification time, and excellent demulsification performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the synthesis principle of the comb-shaped alternating copolymer demulsifier prepared in Example 1.

[0021] Figure 2 This is the infrared spectrum of the comb-shaped alternating copolymer demulsifier prepared in Example 1. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0023] The present application provides a comb copolymer demulsifier, which is a polymer comprising repeating units as shown in formula I,

[0024]

[0025] Wherein, x is selected from an integer of 1-5, and R is selected from C3-C 18 Alkyl, a structure formed by ring-opening of diglycidyl ether compounds and alternating combination with primary amines.

[0026] It is understood that the general chemical structure of the polymer is as shown in Formula II,

[0027]

[0028] Wherein, x is selected from an integer of 1-5, and R is selected from C3-C 18 Alkyl, y is selected from an integer greater than or equal to 1, and the wavy line represents the end group; the end group includes one or two of the following structures:

[0029] -H; -NH-R; that is, the wavy line represents one or two of Formula III, Formula IV; -H; -NH-R.

[0030] Correspondingly, the structure of the comb copolymer demulsifier of the present application includes but is not limited to the following structure:

[0031]

[0032] In other comb copolymer demulsifier structures, the end can be the same as the above three structural formulas, the difference is that it contains The structure has a number of repeating units greater than or equal to 2, and a suitable but non-limiting number of repeating units y=2-50.

[0033] The comb-like copolymer demulsifier described in this application is an alternating copolymer. Compared to conventional hydrophobic-hydrophilic-hydrophobic demulsifiers, this application has longer molecular chains, and the long hydrophobic chains on the polymer side chains have stronger interfacial activity. In the emulsion, it can not only bridge adjacent water droplets, promoting droplet flocculation and coalescence, but also more easily replace the emulsifier on the original interfacial film to form a new composite interfacial film. The composite interfacial film is less stable, giving it stronger demulsification ability. In addition, the structure of this application can improve its dispersibility in crude oil and promote its demulsification ability at low temperatures.

[0034] The present application provides a method for preparing a comb-like copolymer demulsifier, comprising the following steps: using primary amine and diglycidyl ether compounds as raw materials, performing a ring-opening reaction to obtain the comb-like copolymer demulsifier; the molar ratio of the primary amine to the diglycidyl ether compound is 1:1.

[0035] The chain length of the diglycidyl ether compound of the present application is strictly limited. It has 1-5 ethoxy groups and can provide moderate hydrophilicity. The diglycidyl ether compound is selected from ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, and pentaethylene glycol diglycidyl ether; the primary amine is R-NH2, wherein R is selected from C3-C 18 The alkyl group, the primary amine includes but is not limited to n-octylamine, dodecylamine, octadecylamine, preferably, the primary amine is dodecylamine. By strictly controlling the molar ratio of the primary amine and the diglycidyl ether, a ring-opening polymerization reaction is carried out to obtain a comb copolymer demulsifier.

[0036] The mechanism of obtaining the comb-like copolymer demulsifier in this scheme is as follows: primary amine and diglycidyl ether react in an equimolar ratio. The primary amine first reacts with an epoxy group of the diglycidyl ether compound to obtain a structure containing a secondary amine group. The secondary amine group in this structure also has strong activity and can react again with an epoxy group of another diglycidyl ether compound to obtain a tertiary amine structure, that is, the primary amine can react with two epoxy groups in a ring-opening reaction, that is, one primary amine can react with two diglycidyl ethers, and the epoxy groups at both ends can react with the primary amine. Therefore, when the ring-opening polymerization reaction is carried out in a 1:1 ratio, a copolymer with alternating hydrophilic segments and hydrophobic segments will be obtained, in which the hydroxyl groups at both ends and the ethoxy group in the middle are hydrophilic segments, and the primary amine is connected to the hydrophilic segment. The hydrophobic long chain in the primary amine is the hydrophobic end, and the hydrophobic long chain on the copolymer long chain is like the teeth of a comb, thereby obtaining the comb-like copolymer demulsifier in this scheme.

[0037] The structural formula of the diglycidyl ether compound is shown in Formula V. Here, x is an integer from 1 to 5.

[0038] Correspondingly, the mechanism of this scheme can be described by the following reaction process:

[0039]

[0040] Wherein, x is selected from an integer of 1 to 5, and R is selected from C3-C 18 Alkyl, y is selected from an integer greater than or equal to 1, the wavy line represents the omitted repeating unit, and y also represents the number of repetitions of the omitted repeating unit. The repeating unit is

[0041] The temperature of the ring-opening polymerization reaction is 60-150° C., and the reaction time is 6-12 hours.

[0042] The ring-opening polymerization reaction was carried out under the protection of inert gas.

[0043] The present application provides an application of a comb-like copolymer demulsifier in demulsifying crude oil emulsions. The application comprises the following steps: dissolving the comb-like alternating copolymer demulsifier in a solvent to obtain a solution, then mixing the solution with the crude oil emulsion at 40-70°C and standing for 0.5-3 hours. After demulsification, the oil-water interface is clear, the water phase is clear, and the water content in the oil phase is low. The solvent is at least one of water, ethanol, toluene, and xylene, and the amount of the demulsifier added to the crude oil emulsion is 100-500 mg / L.

[0044] The present application is further described below through specific implementation methods.

[0045] Example 1

[0046] A comb copolymer demulsifier, which is a polymer comprising repeating units as shown in formula I,

[0047]

[0048] Correspondingly, its molecular structure is shown in Formula II:

[0049] In each embodiment of this solution, the wavy line represents -H; -NH-C 12 One or both of .

[0050] A method for preparing a comb copolymer demulsifier is as follows: using nitrogen as a protective gas, 1 mol of dodecylamine and 1 mol of diethylene glycol diglycidyl ether (CAS 4206-61-5) are mixed evenly, and reacted at 100°C for 8 hours to obtain a comb copolymer demulsifier. The reaction process is as follows: Figure 1 shown.

[0051] The comb copolymer demulsifier obtained in this embodiment was identified, and the results are as follows: Figure 2 The infrared spectrum of the comb-shaped alternating copolymer demulsifier prepared in Example 1 is shown in FIG. Figure 2 It can be seen that at 3400cm -1 The peak at 2923.6cm is the absorption peak of hydroxyl. -1 and 2854.1cm -1 The peak at 1670.1cm is caused by the stretching vibration of -CH2. -1 and 867.8cm -1The peaks at 1467.6 cm are attributed to the in-plane and out-of-plane bending vibrations of NH. -1 The peak at 1257.4 cm is caused by the stretching vibration of CN. -1 The peak at is caused by CO stretching vibration. These results indicate that the target product was successfully synthesized.

[0052] Example 2

[0053] A comb copolymer demulsifier comprising a repeating unit as shown in formula I,

[0054] x=2,R is C 18 alkyl.

[0055] The general chemical structure is shown in Formula II.

[0056]

[0057] Where x = 2, R is C 18 Alkyl, y is selected from an integer greater than or equal to 1, and the wavy line represents the end group; the end group includes one or two of the following structures:

[0058] -H; -NH-R; that is, the wavy line represents one or two of Formula III, Formula IV; -H; -NH-R.

[0059] A method for preparing a comb-like copolymer demulsifier is as follows: 1 mol of octadecylamine and 1 mol of diethylene glycol diglycidyl ether are uniformly mixed, and the mixture is reacted at 120° C. for 8 hours to obtain the comb-like copolymer demulsifier.

[0060] Example 3

[0061] A comb copolymer demulsifier comprises a repeating unit as shown in formula I:

[0062]

[0063] Its chemical structure is shown in Formula II:

[0064] y is an integer greater than or equal to 1.

[0065] A method for preparing a comb-like copolymer demulsifier is as follows: using nitrogen as a protective gas, 1 mol of n-octylamine and 1 mol of diethylene glycol diglycidyl ether (CAS 4206-61-5) are uniformly mixed, and the mixture is reacted at 100° C. for 6 hours to obtain the comb-like copolymer demulsifier.

[0066] Example 4

[0067] A comb copolymer demulsifier comprises a repeating unit as shown in formula I:

[0068]

[0069] Its chemical structure is shown in Formula II:

[0070] y is an integer greater than or equal to 1.

[0071] A method for preparing a comb-like copolymer demulsifier is as follows: using nitrogen as a protective gas, 1 mol of dodecylamine and 1 mol of ethylene glycol diglycidyl ether (CAS 2224-15-9) are uniformly mixed, and the mixture is reacted at 120° C. for 12 hours to obtain the comb-like copolymer demulsifier.

[0072] Example 5

[0073] A comb copolymer demulsifier comprises a repeating unit as shown in formula I:

[0074]

[0075] Its chemical structure is shown in Formula II:

[0076] y is an integer greater than or equal to 1.

[0077] A method for preparing a comb-like copolymer demulsifier is as follows: using nitrogen as a protective gas, 1 mol of octadecylamine and 1 mol of ethylene glycol diglycidyl ether are uniformly mixed, and the mixture is reacted at 150° C. for 12 hours to obtain the comb-like copolymer demulsifier.

[0078] Comparative Example 1

[0079] A copolymer demulsifier, the preparation method of which is as follows:

[0080] 1 mol of diglycidyl ether compound was completely dissolved in 3 L of xylene, and then transferred to a reactor, and 2 mol of dodecylamine was added, and the reaction was carried out at 100 ° C for 8 hours under nitrogen protection to obtain a reaction product, wherein the diglycidyl ether compound was polyethylene glycol diglycidyl ether, and the structural formula of polyethylene glycol diglycidyl ether was n is an integer of 2; the reaction product is naturally cooled to 100° C., and xylene is removed by distillation under vacuum conditions. In the present application, the molar ratio of the diglycidyl ether compound to the primary amine is 1:2, and the final product has the following structural formula:

[0081]

[0082] Evaluation Test

[0083] The comb-shaped alternating copolymer demulsifiers prepared in Examples 1 to 5 and the low-temperature demulsifier prepared in Comparative Example 1 were used to characterize the demulsification performance of the alternating copolymer demulsifier in crude oil emulsion.

[0084] 150 parts by mass of crude oil (source: Changqing Oilfield, Xi'an, China, density at 25°C: 0.862 g / cm 3 , viscosity at 25°C: 7.6 mPa·s, asphaltene: 14wt%, resin: 6.03wt%, wax: 15.46%, water: 1.6wt%) were added into 350 parts by mass of deionized water and stirred, heated to 70°C, and then stirred at a speed of 11000 r / min for 20 minutes. This process was repeated three times until a stable oil-in-water emulsion was obtained.

[0085] The comb-shaped alternating copolymer demulsifiers prepared in Examples 1 to 5 and the low-temperature demulsifier prepared in Comparative Example 1 were added to ethanol to prepare demulsifier solutions with a mass fraction of 0.4%, namely experimental groups 1-6.

[0086] 1 part by volume of the above-mentioned comb-shaped alternating copolymer demulsifier solution and the solution of Comparative Example 1 were added to 20 parts by volume of crude oil emulsion and then shaken at 2500 rpm for 2 minutes to mix uniformly. The mixture was then transferred to a 40°C water bath and allowed to stand for 3 hours. The demulsification efficiency was characterized by measuring the dehydration rate (referring to the Petroleum and Natural Gas Industry Standard SY / T5281-2000 of the People's Republic of China). The results are shown in Table 1.

[0087] Table 1 Demulsification results of experimental groups 1-5

[0088] Group Demulsifier (mg / L) Demulsification efficiency (%) Experimental Group 1 200 100 Experimental Group 2 200 96.7 Experimental Group 3 200 95.1 Experimental Group 4 200 92.4 Experimental Group 5 200 92.2 Experimental Group 6 200 88.1

[0089] Note: "Demulsifier (mg / L)" in the table refers to the concentration of the comb-like alternating copolymer demulsifier and the demulsifier prepared in Comparative Example 1 in the crude oil emulsion.

[0090] Table 1 shows that the comb-like alternating copolymer demulsifiers prepared in Examples 1-4 all have excellent demulsification performance. Example 1 has the highest demulsification efficiency. In comparison, the comb-like alternating copolymer demulsifier prepared in Example 5 has a relatively poor demulsification effect, primarily due to its poor hydrophilicity and low interfacial activity. Furthermore, the demulsification efficiency in Comparative Example 1 is also lower than that in this work.

[0091] Based on the comb-like alternating copolymer demulsifier prepared in Example 1, comb-like alternating copolymer demulsifier solutions with different concentrations were prepared to characterize the demulsification performance of the comb-like alternating copolymer demulsifiers with different concentrations in crude oil emulsion.

[0092] 150 parts by mass of crude oil were added to 350 parts by mass of deionized water, stirred and mixed, heated to 70° C., and then stirred at a speed of 11,000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0093] Different weight portions of the comb-shaped alternating copolymer demulsifier prepared in Example 1 were added to ethanol to prepare demulsifier solutions with mass fractions of 1%, 0.8%, 0.6%, 0.4%, and 0.2%, respectively. The obtained samples were recorded as experimental groups 6-10; the blank group was 0%, and the sample was recorded as experimental group 11.

[0094] 1 part by volume of the experimental groups 6-11 was added to 20 parts by volume of the crude oil emulsion and then shaken at 2500 rpm for 2 minutes to mix evenly. The mixture was then transferred to a 40°C water bath and allowed to stand for 3 hours. The dehydration rate was measured. The results are shown in Table 2.

[0095] Table 2 Demulsification results of experimental groups 6-11

[0096] Group Comb-like alternating copolymer demulsifier (mg / L) Demulsification efficiency (%) Experimental Group 6 500 100 Experimental Group 7 400 100 Experimental Group 8 300 100 Experimental Group 9 200 100 Experimental group 10 100 69.7 Experimental Group 11 0 0

[0097] Note: "Comb-like alternating copolymer demulsifier (mg / L)" in the table refers to the concentration of comb-like alternating copolymer demulsifier in crude oil emulsion.

[0098] As shown in Table 2, the comb-shaped alternating copolymer demulsifier provided by the present invention has good demulsification performance. When the concentration of the comb-shaped alternating copolymer demulsifier is 100 mg / L, the demulsification efficiency is 69.7%; when the demulsification concentration is 200 mg / L, the demulsification efficiency can reach 100%.

[0099] Based on the comb-like alternating copolymer demulsifier prepared in Example 1, experimental groups 12-15 were sequentially established to characterize the demulsification performance of the comb-like alternating copolymer demulsifier at different temperatures and times.

[0100] 150 parts by mass of crude oil were added to 350 parts by mass of deionized water, stirred and mixed, heated to 70° C., and then stirred at a speed of 11,000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0101] The comb-shaped alternating copolymer demulsifier prepared in Example 1 was added to ethanol to prepare a solution with a mass fraction of 0.4%, that is, the concentration of the demulsifier was 200 mg / mL.

[0102] 1 part by volume of the above-mentioned comb-shaped alternating copolymer demulsifier solution was added to 20 parts by volume of crude oil emulsion and then shaken at 2500 rpm for 2 minutes to mix evenly. The mixture was then transferred to water baths set at different temperatures and allowed to stand. The dehydration rates were measured. The results are shown in Table 3.

[0103] Table 3 Demulsification results of experimental groups 12-15

[0104]

[0105] As shown in Table 3, the comb-shaped alternating copolymer demulsifier provided by the present invention can achieve 100% demulsification efficiency in 180 minutes at 40°C, and 100% demulsification efficiency in 30 minutes at 70°C.

[0106] Based on the comb-like alternating copolymer demulsifier prepared in Example 1, experimental groups 16-21 were sequentially established to characterize the demulsification performance of the comb-like alternating copolymer demulsifier under different pH conditions.

[0107] 150 parts by mass of crude oil was added to 350 parts by mass of deionized water and stirred. The pH value was adjusted by adding hydrochloric acid or sodium hydroxide, and the mixture was heated to 70°C and stirred at 11,000 rpm for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0108] The comb-shaped alternating copolymer demulsifier prepared in Example 1 was added to ethanol to prepare a solution with a mass fraction of 0.4%.

[0109] 1 part by volume of the above-mentioned comb-shaped alternating copolymer demulsifier solution was added to 20 parts by volume of crude oil emulsions of different pH values ​​and then shaken at 2500 rpm for 2 minutes to mix them evenly. The mixtures were then transferred to a 40°C water bath and allowed to stand for 3 hours. The dehydration rates were measured. The results are shown in Table 4.

[0110] Table 4 Demulsification results of experimental groups 16-21

[0111]

[0112]

[0113] As shown in Table 4, the comb-shaped alternating copolymer demulsifier provided by the present invention has a high demulsification efficiency within the pH range of strong acid and strong base.

[0114] Based on the comb-shaped alternating copolymer demulsifier prepared in Example 1, experimental groups 22-27 were sequentially established to characterize the demulsification performance of the alternating copolymer demulsifier under different salinity conditions.

[0115] 150 parts by mass of crude oil were added to 350 parts by mass of deionized water and stirred. The salinity was adjusted by adding sodium chloride, heated to 70°C, and then stirred at a speed of 11,000 r / min for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0116] The comb-shaped alternating copolymer demulsifier prepared in Example 1 was added to ethanol to prepare a solution with a mass fraction of 0.4%, that is, the concentration of the demulsifier was 200 mg / mL.

[0117] 1 part by volume of the above-mentioned comb-shaped alternating copolymer demulsifier solution was added to 20 parts by volume of crude oil emulsions of different pH values ​​and then shaken at 2500 rpm for 2 minutes to mix them evenly. The mixtures were then transferred to a 40°C water bath and allowed to stand for 3 hours. The dehydration rates were measured. The results are shown in Table 5.

[0118] Table 5 Demulsification results of experimental groups 22-27

[0119] Group Salinity (mg / L) Demulsification efficiency (%) Experimental group 22 0 100 Experimental Group 23 10000 100 Experimental group 24 20000 100 Experimental group 25 30000 100 Experimental group 26 40000 100 Experimental group 27 50000 100

[0120] It can be seen from Table 5 that the comb-shaped alternating copolymer demulsifier provided by the present invention can have a stable demulsification efficiency under high salinity conditions, indicating that the demulsifier has high salt resistance.

[0121] The invention provides a comb-shaped alternating copolymer demulsifier suitable for demulsifying crude oil emulsions, and has the characteristics of simple preparation method, short demulsification time, low demulsification temperature, excellent demulsification performance, etc.

[0122] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A comb copolymer demulsifier, characterized in that: It is a polymer comprising repeating units as shown in formula I, Wherein, x is selected from an integer of 1-5, and R is selected from C3-C 18 alkyl.

2. A method for preparing the comb copolymer demulsifier according to claim 1, characterized in that: The method comprises the following steps: using diglycidyl ether compounds and primary amines as raw materials to carry out ring-opening polymerization reaction to obtain the comb-shaped copolymer demulsifier, wherein the molar ratio of the primary amine to the diglycidyl ether compounds is 1:

1.

3. The method for preparing the comb copolymer demulsifier according to claim 2, wherein The diglycidyl ether compound includes one or more of ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, and pentaethylene glycol diglycidyl ether.

4. The method for preparing the comb copolymer demulsifier according to claim 2, wherein The primary amine is R-NH2, wherein R is selected from C3-C 18 alkyl.

5. The method for preparing the comb copolymer demulsifier according to claim 2, wherein The temperature of the ring-opening polymerization reaction is 60-150° C., and the reaction time is 6-12 hours.

6. The method for preparing the comb copolymer demulsifier according to claim 2, wherein: The primary amine is dodecylamine.

7. The method for preparing the comb copolymer demulsifier according to claim 2, characterized in that: The diglycidyl ether compound is diethylene glycol diglycidyl ether.

8. The method for preparing the comb copolymer demulsifier according to claim 2, wherein: The ring-opening polymerization reaction is carried out under the protection of inert gas.

9. Use of the comb copolymer demulsifier according to claim 1 in demulsification of crude oil emulsion.

10. The use according to claim 9, characterized in that The demulsification temperature is 40-70°C.

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