Crude oil demulsifier and preparation method thereof

Abstract

The invention relates to the technical field of demulsifiers, and discloses a crude oil demulsifier and a preparation method thereof.The preparation method comprises the steps that polyethylene glycol monomethyl ether and ethylenediamine-N, N '-diacetic acid react to obtain an intermediate; and then reacting with 4-chloromethyl benzoic acid (methoxypolyethylene glycol) ester to obtain the crude oil demulsifier. The surfactant contains a plurality of benzene ring structures and hydrophilic quaternary ammonium salt groups, has strong oil-water amphipathy, and shows lower surface tension and oil-water interfacial tension. The demulsifier has quaternary ammonium salt active groups and a plurality of polyether chain segments, forms a unique star-shaped structure, shows very high demulsification performance and dehydration rate, and contains a plurality of high-temperature-resistant benzene ring structures, so that the heat resistance and structural stability of the demulsifier are improved.

Description

Technical Field

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

[0002] In the process of oil extraction, the oil recovery rate can be improved through polymer flooding, water flooding and other technologies. However, with the continuous exploitation of oil fields, the water content in oil well produced fluid and crude oil is increasing. The produced crude oil emulsion contains many chemical additives, complex components, and the emulsion stability is too good, which makes it difficult to demulsify the emulsion. Therefore, the development of high-performance demulsifiers is the focus of research.

[0003] The current demulsifiers mainly include polyether demulsifiers, cationic demulsifiers, polysaccharide demulsifiers, etc. According to the molecular structure, they can be divided into linear, hyperbranched, comb-shaped, star-shaped demulsifiers, etc. The Chinese invention patent with publication number CN118562525A discloses a high temperature resistant crude oil demulsifier and a preparation method thereof, in which a triazine structure, a hyperbranched structure and silicone oil are introduced into a silicone oil modified polyether, and polydopamine PDA is coated on a MXene nanosheet substrate, and a metal organic framework material U iO-66 is generated in situ, and the obtained crude oil demulsifier has good high temperature resistance and demulsification ability, but the preparation raw materials of the demulsifier of the patent are more, and the preparation method is complicated, which is not conducive to practical application. Summary of the invention

[0004] The technical problem solved by the present invention is as follows: The present invention provides a star-shaped cationic polyether crude oil demulsifier with good heat resistance and excellent demulsification performance.

[0005] The technical solution of the present invention is a method for preparing a crude oil demulsifier, comprising the following steps:

[0006] (1) Add polyethylene glycol monomethyl ether, ethylenediamine-N,N'-diacetic acid and p-toluenesulfonic acid to toluene, heat to reaction temperature, perform vacuum distillation after reaction, wash with petroleum ether and dry to obtain an intermediate. The molecular weight of polyethylene glycol monomethyl ether is 400-750.

[0007] (2) Add the intermediate, catalyst, and 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to N,N-dimethylformamide to carry out a substitution reaction, then add 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to carry out a quaternization reaction, perform vacuum distillation, wash with ethanol, and dry to obtain a crude oil demulsifier. The reaction formula is:

[0008]

[0009] Preferably, the reaction temperature in (1) is 80-90°C and the reaction time is 8-12h.

[0010] Preferably, the molar ratio of polyethylene glycol monomethyl ether, ethylenediamine-N,N'-diacetic acid and p-toluenesulfonic acid in (1) is (2-2.4):1:(0.075-0.09).

[0011] Preferably, the temperature during the substitution reaction in (2) is 35-50° C., and the reaction time is 6-8 h; the temperature during the quaternization reaction is 80-100° C., and the reaction time is 24-36 h.

[0012] Preferably, in (2), the molar ratio of the intermediate, the catalyst, and 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester is 1:(2-2.2):(4-4.8).

[0013] Preferably, the catalyst is sodium hydroxide or potassium hydroxide.

[0014] Preferably, the preparation method of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester is as follows: polyethylene glycol monomethyl ether, 4-chloromethylbenzoic acid, and p-toluenesulfonic acid in a molar ratio of 1: (1.4-1.8): (0.05-0.06) are added to toluene, heated to 80-95°C, the reaction time is 5-7h, and after the reaction, the reaction is distilled under reduced pressure, washed with petroleum ether, and dried to obtain 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester. The molecular weight of polyethylene glycol monomethyl ether is 400-750. The reaction formula is:

[0015]

[0016] Technical effect: The crude oil demulsifier prepared by the present invention contains multiple benzene ring structures and hydrophilic quaternary ammonium salt groups, has strong oil-water amphiphilicity, exhibits lower surface tension and oil-water interfacial tension, and has excellent surface activity.

[0017] The demulsifier of the invention has a quaternary ammonium salt active group and a plurality of polyether chain segments to form a unique star-shaped structure, so that the demulsifier molecules can be adsorbed on the oil-water interface to replace the original emulsifier molecules to form a new oil-in-oil type structure, so that the oil-water interface film becomes thinner and the oil-water interface film strength is reduced, the interface film is broken and a sedimentation effect is formed, so that the emulsion is demulsified. The demulsifier of the invention shows a very high dehydration rate and a strong demulsification performance. The demulsifier contains a plurality of high-temperature resistant benzene ring structures, which is beneficial to improving the heat resistance and structural stability of the demulsifier. After high-temperature heat treatment, the demulsifier is not easy to be thermally decomposed and still maintains a relatively high dehydration rate and demulsification performance. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is described in detail with reference to the following specific embodiments.

[0019] Embodiment 1:

[0020] (1) Add 20 mmol of polyethylene glycol monomethyl ether 600, 36 mmol of 4-chloromethyl benzoic acid, and 1.2 mmol of p-toluenesulfonic acid to 60 mL of toluene, heat to 80°C, and react for 7 h. After the reaction, distill under reduced pressure, wash with petroleum ether, and dry to obtain 4-chloromethyl benzoic acid (polyethylene glycol monomethyl ether) ester.

[0021] (2) Add 24 mmol polyethylene glycol monomethyl ether 600, 10 mmol ethylenediamine-N,N'-diacetic acid, and 0.75 mmol p-toluenesulfonic acid to 60 mL toluene, heat to 80°C, stir to react for 12 h, distill under reduced pressure, wash with petroleum ether, and dry to obtain an intermediate.

[0022] (3) Add 10 mmol of the intermediate, 20 mmol of potassium hydroxide, and 20 mmol of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to 500 mL of N,N-dimethylformamide, heat to 40°C, stir and react for 6 hours, then heat to 100°C, add 26 mmol of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester, stir and react for 24 hours, distill under reduced pressure, wash with ethanol, and dry to obtain a crude oil demulsifier.

[0023] Embodiment 2:

[0024] (1) Add 20 mmol of polyethylene glycol monomethyl ether 750, 28 mmol of 4-chloromethyl benzoic acid, and 1.1 mmol of p-toluenesulfonic acid to 70 mL of toluene, heat to 95° C., and react for 5 h. After the reaction, distill under reduced pressure, wash with petroleum ether, and dry to obtain 4-chloromethyl benzoic acid (polyethylene glycol monomethyl ether) ester.

[0025] (2) Add 20 mmol polyethylene glycol monomethyl ether 750, 10 mmol ethylenediamine-N,N'-diacetic acid, and 0.9 mmol p-toluenesulfonic acid to 60 mL toluene, heat to 80°C, stir to react for 10 hours, evaporate under reduced pressure, wash with petroleum ether, and dry to obtain an intermediate.

[0026] (3) Add 10 mmol of the intermediate, 20 mmol of potassium hydroxide, and 20 mmol of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to 500 mL of N,N-dimethylformamide, heat to 35°C, stir and react for 8 hours, then heat to 80°C, add 20 mmol of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester, stir and react for 36 hours, distill under reduced pressure, wash with ethanol, and dry to obtain a crude oil demulsifier.

[0027] Embodiment 3:

[0028] (1) Add 20 mmol of polyethylene glycol monomethyl ether 400, 30 mmol of 4-chloromethyl benzoic acid and 1 mmol of p-toluenesulfonic acid to 50 mL of toluene, heat to 85°C, react for 7 h, distill under reduced pressure after the reaction, wash with petroleum ether, and dry to obtain 4-chloromethyl benzoic acid (polyethylene glycol monomethyl ether) ester.

[0029] (2) Add 22 mmol polyethylene glycol monomethyl ether 400, 10 mmol ethylenediamine-N,N'-diacetic acid, and 0.9 mmol p-toluenesulfonic acid to 60 mL toluene, heat to 90°C, stir to react for 8 hours, evaporate under reduced pressure, wash with petroleum ether, and dry to obtain an intermediate.

[0030] (3) Add 10 mmol of the intermediate, 22 mmol of sodium hydroxide, and 20 mmol of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to 300 mL of N,N-dimethylformamide, heat to 50°C, stir and react for 6 hours, then heat to 100°C, add 28 mmol of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester, stir and react for 24 hours, distill under reduced pressure, wash with ethanol, and dry to obtain a crude oil demulsifier.

[0031] Comparative Example 1: The intermediate prepared in Example 1 was used as a demulsifier.

[0032] Comparative Example 2:

[0033] (1) Add 10 mmol of the intermediate (prepared in the same manner as in Example 1), 20 mmol of potassium hydroxide, and 20 mmol of 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to 500 mL of N,N-dimethylformamide, heat to 40° C., stir and react for 6 h, distill under reduced pressure, wash with ethanol, and dry to obtain a crude oil demulsifier that does not contain a quaternary ammonium salt group. The structural formula is:

[0034] Comparative Example 3:

[0035] (1) Add polyethylene glycol monomethyl ether, triethylamine and chloroacetyl chloride to dichloromethane in an ice bath, and then carry out esterification reaction at 25°C for 24 hours. After the reaction, add saturated sodium chloride solution, stir and stand for stratification, collect the dichloromethane organic layer, distill under reduced pressure, and dry to obtain chloroacetate polyethylene glycol monomethyl ether. The structural formula is:

[0036] (2) Add 10 mmol of the intermediate (prepared in the same manner as in Example 1), 20 mmol of potassium hydroxide, and 26 mmol of chloroacetate polyethylene glycol monomethyl ether to 500 mL of N,N-dimethylformamide, heat to 40°C, stir and react for 6 hours, then heat to 100°C, add 20 mmol of chloroacetate polyethylene glycol monomethyl ether, stir and react for 24 hours, distill under reduced pressure, wash with ethanol, and dry to obtain a crude oil demulsifier that does not contain a benzene ring. The structural formula is:

[0037] The demulsifier was added into distilled water to prepare a solution with a mass concentration of 50-200 mg / L. The surface tension of the solution was tested using a surface tension meter at room temperature.

[0038] At room temperature, the oil-water interfacial tension of kerosene and water was tested using a surface tension meter, and the demulsifier dosage was 50-200 mg / L.

[0039] The test results are shown in Table 1-2.

[0040] Table 1 Surface tension test

[0041]

[0042] Table 2 Interfacial tension test

[0043]

[0044]

[0045] After testing, the crude oil demulsifiers prepared in Examples 1-3 contain multiple benzene ring structures and hydrophilic quaternary ammonium salt groups, have strong oil-water affinity, exhibit lower surface tension and oil-water interfacial tension, and have excellent surface activity.

[0046] Add 200 mg / L crude oil demulsifier to crude oil emulsion (from Huabei Oilfield, oil-in-water emulsion, water content about 87.42%), shear disperse. Test the dehydration rate according to SY / T 5281-2000 standard (bottle test method), temperature 30°C, time 2h.

[0047] The crude oil demulsifier was heat treated at 70-100°C for 120h, cooled to room temperature, and then the dehydration rate was tested.

[0048] The test results are shown in Table 3.

[0049] Table 3 Dehydration rate test

[0050]

[0051] After testing, compared with comparative examples 1-3, the dehydration rate of the crude oil demulsifier of Examples 1-3 reaches 69.5-78.3%, and the demulsifier contains multiple polyether segments to form a unique star-shaped molecular chain structure, and also contains multiple high-temperature resistant benzene ring structures, which is beneficial to improving the heat resistance and structural stability of the demulsifier. After high-temperature heat treatment, the demulsifier is not easy to be thermally decomposed, and still maintains a high dehydration rate and demulsification performance.

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a crude oil demulsifier, characterized in that: The preparation method comprises the following steps: (1) Adding polyethylene glycol monomethyl ether, ethylenediamine-N,N'-diacetic acid and p-toluenesulfonic acid to toluene, heating to the reaction temperature, performing reduced pressure distillation after the reaction, washing and drying to obtain an intermediate; (2) adding an intermediate, a catalyst, and 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to N,N-dimethylformamide to carry out a substitution reaction, then adding 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester to carry out a quaternization reaction, performing reduced pressure distillation, washing, and drying to obtain a crude oil demulsifier.

2. The method for preparing a crude oil demulsifier according to claim 1, characterized in that: The reaction temperature in (1) is 80-90°C and the reaction time is 8-12h.

3. The method for preparing a crude oil demulsifier according to claim 1, characterized in that: The molar ratio of polyethylene glycol monomethyl ether, ethylenediamine-N,N'-diacetic acid and p-toluenesulfonic acid in (1) is (2-2.4):1:(0.075-0.09).

4. The method for preparing a crude oil demulsifier according to claim 1, characterized in that: The temperature of the substitution reaction in (2) is 35-50°C, and the reaction time is 6-8h; the temperature of the quaternization reaction is 80-100°C, and the reaction time is 24-36h.

5. The method for preparing a crude oil demulsifier according to claim 1, characterized in that: In the above (2), the molar ratio of the intermediate, the catalyst, and 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester is 1:(2-2.2):(4-4.8).

6. The method for preparing a crude oil demulsifier according to claim 1, characterized in that: The catalyst is sodium hydroxide or potassium hydroxide.

7. The method for preparing a crude oil demulsifier according to claim 5, characterized in that: The preparation method of the 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester is as follows: polyethylene glycol monomethyl ether, 4-chloromethylbenzoic acid and p-toluenesulfonic acid in a molar ratio of 1: (1.4-1.8): (0.05-0.06) are added to toluene, heated to 80-95° C., reacted for 5-7 hours, and after the reaction, distilled under reduced pressure, washed and dried to obtain 4-chloromethylbenzoic acid (polyethylene glycol monomethyl ether) ester.

8. The method for preparing a crude oil demulsifier according to claim 7, characterized in that: The molecular weight of the polyethylene glycol monomethyl ether is 400-750.

9. A crude oil demulsifier obtained by the preparation method according to any one of claims 1 to 8.

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