Multi-branch ionic liquid demulsifier as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oilfield chemical auxiliaries, and discloses a multi-branch ionic liquid demulsifier as well as a preparation method and application thereof. The synthesis process and conditions of the multi-branch ionic liquid demulsifier are relatively simple, trimethylolpropane is modified by chloroacetyl chloride, and then long-chain alkyl diethanol amine is grafted on the modified trimethylolpropane to obtain the multi-branch ionic liquid demulsifier. The center of the multi-branch ionic liquid demulsifier is hydrophilic, and the multi-branch ionic liquid demulsifier has a multi-branch hydrophobic long chain, can be quickly dispersed in a continuous oil phase, is adsorbed on an oil-water interface, and reacts with an interface active substance for demulsification; in addition, due to a plurality of cation centers and positive charges, demulsification can be enhanced through electrostatic interaction; therefore, the multi-branch ionic liquid demulsifier disclosed by the invention has good low-temperature demulsification capability, low demulsifier dosage, short demulsification time and high demulsification efficiency, and has a wide application prospect in demulsification treatment of crude oil emulsion.

Description

Technical Field

[0001] The present invention belongs to the technical field of oilfield chemical additives, and particularly relates to a multi-branched ionic liquid demulsifier, a preparation method thereof and an application thereof. Background Art

[0002] When producing crude oil from an oil reservoir, stable emulsions are usually formed. These emulsions are stabilized by active compounds naturally present in the crude oil, such as asphaltenes, resins, and fine solid particles. Before transportation and refining, the emulsified water should be removed from the crude oil. The presence of water in the oil can cause some problems, such as pipeline corrosion, an increase in the viscosity of the crude oil (resulting in difficult oil transportation), and catalyst poisoning during the refining process. Using chemicals as demulsifiers is one of the best methods to promote emulsion dehydration.

[0003] Commercial demulsifiers are usually mixtures of surfactants with different hydrophilic-lipophilic balances, and the specific ratio depends on the composition of the emulsion and the type of crude oil. However, the production process of commercial demulsifiers is relatively dangerous and complex, with poor demulsification effect on high-viscosity crude oil, high demulsification temperature, and large dosage of demulsifier. Chinese Patent CN101255354A developed a non-polyether heavy oil demulsifier and a preparation method thereof, which are made by copolymerizing butyl acrylate and acrylic acid; Chinese Patent CN102399576A disclosed a new type of crude oil demulsifier and a preparation method thereof, which are esterified from a butyl acrylate-acrylic acid copolymer and a polyether demulsifier; the above patent technologies require more raw materials, the synthesis process is relatively complex, the polymerization process is difficult to control, and the prepared demulsifier has a long demulsification time and low demulsification efficiency, failing to meet the requirements of on-site applications. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-branched ionic liquid demulsifier, a preparation method thereof and an application thereof in view of the deficiencies in the prior art. The multi-branched ionic liquid demulsifier has good low-temperature demulsification ability, low dosage of demulsifier, short demulsification time, and high demulsification efficiency.

[0005] To solve the technical problems proposed by the present invention, the present invention provides a multi-branched ionic liquid demulsifier, and its molecular structural formula is:

[0006]

[0007] In the formula, R is an alkyl chain having 8-18 carbon atoms.

[0008] The present invention also provides a preparation method of a multi-branched ionic liquid demulsifier, including the following steps:

[0009] 1) Add trimethylolpropane to solvent I, mix evenly, then add chloroacetyl chloride. After the reaction, distill off the solvent and unreacted chloroacetyl chloride under reduced pressure to obtain modified trimethylolpropane;

[0010] 2) Add the modified trimethylolpropane into Solvent I. After mixing evenly, add the long-chain alkyldiethanolamine, heat for reaction, and remove the solvent by vacuum distillation to obtain the multi-branched ionic liquid demulsifier.

[0011] In the above solution, Solvent I is one or more of tetrahydrofuran, dioxane, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0012] In the above solution, the molar ratio of trimethylolpropane to chloroacetyl chloride is 1:(2 - 6).

[0013] In the above solution, the reaction temperature in step 1) is 20 - 50 °C, and the reaction time is 10 - 24 h.

[0014] In the above solution, the long-chain alkyldiethanolamine is one or more of octyldiethanolamine, dodecyldiethanolamine, hexadecyldiethanolamine, and octadecyldiethanolamine.

[0015] In the above solution, the molar ratio of trimethylolpropane to long-chain alkyldiethanolamine is 1:(2 - 6).

[0016] In the above solution, the reaction temperature in step 2) is 100 - 150 °C, and the reaction time is 10 - 24 h.

[0017] The present invention also provides an application of the multi-branched ionic liquid demulsifier in demulsifying crude oil emulsions. The application method is as follows: dissolve the multi-branched ionic liquid demulsifier in Solvent II to obtain a demulsifier solution, and then mix the demulsifier solution with the crude oil emulsion at the demulsification temperature and let it stand.

[0018] In the above solution, Solvent II is one or more of water, ethanol, and xylene.

[0019] In the above solution, the mass fraction of the multi-branched ionic liquid demulsifier in the demulsifier solution is 0.1 - 0.5%.

[0020] In the above solution, the volume ratio of the demulsifier solution to the crude oil emulsion is 1:(10 - 20).

[0021] In the above solution, the concentration of the multi-branched ionic liquid demulsifier in the crude oil emulsion is 100 - 250 mg / L.

[0022] In the above solution, the demulsification temperature is 50 - 70 °C, and the standing time is 1 - 2 h.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] The multi-branched ionic liquid demulsifier provided by the present invention has a hydrophilic center and multi-branched hydrophobic long chains, endowing it with good wettability, dispersibility in the continuous oil phase, and surface and interfacial activity. It can quickly disperse in the continuous oil phase, adsorb on the oil-water interface, interact with interfacial active substances, etc., reduce the oil-water interfacial tension, weaken the stability of the interfacial film or directly destroy the interfacial film, thereby inducing demulsification. In addition, the multi-branched ionic liquid demulsifier of the present invention has multiple cationic centers, and the demulsifier molecules carry positive charges, which can strengthen the interaction between the demulsifier molecules and the interfacial film through electrostatic neutralization, and reduce the stability of the interfacial film. Therefore, the multi-branched ionic liquid demulsifier of the present invention has good low-temperature demulsification ability, low demulsifier dosage, short demulsification time, high demulsification efficiency, and relatively simple synthesis process and conditions. Detailed implementation mode

[0025] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments.

[0026] Example 1

[0027] A multi-branched ionic liquid demulsifier, whose molecular structural formula is:

[0028] R is C 12 H 25 。

[0029] The preparation method of the above multi-branched ionic liquid demulsifier includes the following steps:

[0030] 1) Add 0.1 mol of trimethylolpropane to 50 mL of dioxane, mix evenly, then add 0.4 mol of chloroacetyl chloride, react at 30 °C for 24 h, and remove the solvent and unreacted chloroacetyl chloride by vacuum distillation to obtain modified trimethylolpropane;

[0031] 2) Add the modified trimethylolpropane to 100 mL of N,N-dimethylformamide, mix evenly, then add 0.4 mol of dodecyldiethanolamine, heat to 100 °C and react for 24 h, and remove the solvent by vacuum distillation to obtain the multi-branched ionic liquid demulsifier.

[0032] Example 2

[0033] A multi-branched ionic liquid demulsifier, whose molecular structural formula is:

[0034] R is C 18 H 37 。

[0035] The preparation method of the above multi-branched ionic liquid demulsifier includes the following steps:

[0036] 1) Add 0.1 mol of trimethylolpropane to 50 mL of N,N-dimethylformamide. After mixing evenly, add 0.5 mol of chloroacetyl chloride and react at 40 °C for 15 h. Remove the solvent and unreacted chloroacetyl chloride by vacuum distillation to obtain modified trimethylolpropane;

[0037] 2) Add the modified trimethylolpropane to 100 mL of dimethyl sulfoxide. After mixing evenly, add 0.5 mol of octadecyl diethanolamine and heat to 120 °C to react for 18 h. Remove the solvent by vacuum distillation to obtain a multi-branched ionic liquid demulsifier.

[0038] Example 3

[0039] A multi-branched ionic liquid demulsifier, whose molecular structural formula is:

[0040] R is C 8 H 17 .

[0041] The preparation method of the above multi-branched ionic liquid demulsifier includes the following steps:

[0042] 1) Add 0.1 mol of trimethylolpropane to 50 mL of dimethyl sulfoxide. After mixing evenly, add 0.6 mol of chloroacetyl chloride and react at 50 °C for 12 h. Remove the solvent and unreacted chloroacetyl chloride by vacuum distillation to obtain modified trimethylolpropane;

[0043] 2) Add the modified trimethylolpropane to 100 mL of N,N-dimethylformamide. After mixing evenly, add 0.6 mol of octyl diethanolamine and heat to 140 °C to react for 12 h. Remove the solvent by vacuum distillation to obtain a multi-branched ionic liquid demulsifier.

[0044] Application Example 1

[0045] Add 150 parts by weight of crude oil to 350 parts by weight of water, heat to 60 °C and stir at a speed of 11000 r / min for 20 minutes to obtain a stable crude oil emulsion (water-in-oil emulsion).

[0046] Dissolve the multi-branched ionic liquid demulsifier in Examples 1-3 in a mixed solution of xylene and ethanol with a volume ratio of 75:25 to obtain a demulsifier solution with a mass fraction of 0.4%; then add 1 volume part of the demulsifier solution to 20 volume parts of the crude oil emulsion, shake well and mix evenly, and let it stand in a 50 °C water bath for 2 h. Measure the dehydration rate to characterize the demulsification efficiency, and the results are shown in Table 1.

[0047] Table 1

[0048] Group Demulsification efficiency (%) Example 1 96.3 Example 2 93.1 Example 3 88.5

[0049] As can be seen from Table 1, the multi-branched ionic liquid demulsifiers in Examples 1-3 exhibit excellent demulsification performance at relatively low dosages, as well as relatively low demulsification temperatures and demulsification times.

[0050] Application Example 2

[0051] Add 150 parts by weight of crude oil to 350 parts by weight of water, heat to 60 °C, and stir at a speed of 11000 r / min for 20 minutes to obtain a stable crude oil emulsion (water-in-oil emulsion).

[0052] Take 4 parts of the multi-branched ionic liquid demulsifier in Example 1 and dissolve them separately in a mixed solution of xylene and ethanol with a volume ratio of 75:25 to prepare demulsifier solutions with mass fractions of 0.5%, 0.4%, 0.3%, and 0.2% respectively; then take 1 volume part of the above demulsifier solutions with different mass fractions and add them to 20 volume parts of the crude oil emulsion, shake well and mix evenly, and let it stand in a 50 °C water bath for 2 h. Measure the dehydration rate to characterize the demulsification efficiency, and the results are shown in Table 2.

[0053] Table 2

[0054]

[0055] As can be seen from Table 2, when the concentration of the multi-branched ionic liquid demulsifier of the present invention in the crude oil emulsion is 100-250 mg / L, a relatively high demulsification efficiency can be achieved.

[0056] Application Example 3

[0057] Add 150 parts by weight of crude oil to 350 parts by weight of water, heat to 60 °C, and stir at a speed of 11000 r / min for 20 minutes to obtain a stable crude oil emulsion (water-in-oil emulsion).

[0058] Dissolve the multi-branched ionic liquid demulsifier in Example 1 in a mixed solution of xylene and ethanol with a volume ratio of 75:25 to obtain a demulsifier solution with a mass fraction of 0.4%; divide this demulsifier solution into 4 parts, and mix them separately and evenly with 20 times the volume of the crude oil emulsion by shaking well. Then let them stand in a water bath at 40 °C, 50 °C, 60 °C, and 70 °C respectively, and measure the dehydration rate to characterize the demulsification efficiency. The results are shown in Table 3.

[0059] Table 3

[0060]

[0061] As can be seen from Table 3, the multi-branched ionic liquid demulsifier of the present invention can achieve a relatively high demulsification efficiency and a relatively short demulsification time under low temperature conditions of 50-70 °C.

[0062] In summary, the invented multi-branched ionic liquid demulsifier has the characteristics of good low-temperature demulsification ability, low demulsifier dosage, short demulsification time, high demulsification efficiency, etc.

[0063] The above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here, and the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A multi-branched ionic liquid demulsifier, characterized in that the molecular structural formula is: In the formula, R is an alkyl chain having 8-18 carbon atoms.

2. A preparation method of the multi-branched ionic liquid demulsifier according to claim 1, characterized in that it includes the following steps: 1) Add trimethylolpropane to solvent I, mix evenly and then add chloroacetyl chloride. After the reaction, remove the solvent and unreacted chloroacetyl chloride by vacuum distillation to obtain modified trimethylolpropane; 2) Add the modified trimethylolpropane to solvent I, mix evenly and then add long-chain alkyldiethanolamine, heat and react, and remove the solvent by vacuum distillation to obtain the multi-branched ionic liquid demulsifier.

3. According to the preparation method of the multi-branched ionic liquid demulsifier described in claim 2, characterized in that the molar ratio of the trimethylolpropane to the chloroacetyl chloride is 1:(2-6).

4. According to the preparation method of the multi-branched ionic liquid demulsifier described in claim 2, characterized in that the reaction temperature in step 1) is 20-50°C, and the reaction time is 10-24h.

5. According to the preparation method of the multi-branched ionic liquid demulsifier described in claim 2, characterized in that the long-chain alkyldiethanolamine is one or more of octyldiethanolamine, dodecyldiethanolamine, cetyl diethanolamine, and stearyldiethanolamine.

6. According to the preparation method of the multi-branched ionic liquid demulsifier described in claim 2, characterized in that the molar ratio of the trimethylolpropane to the long-chain alkyldiethanolamine is 1:(2-6).

7. According to the preparation method of the multi-branched ionic liquid demulsifier described in claim 2, characterized in that the reaction temperature in step 2) is 100-150°C, and the reaction time is 10-24h.

8. According to the preparation method of the multi-branched ionic liquid demulsifier described in claim 2, characterized in that the solvent I is one or more of tetrahydrofuran, dioxane, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

9. Application of the multi-branched ionic liquid demulsifier according to claim 1 or the multi-branched ionic liquid demulsifier prepared by the preparation method described in any one of claims 2-8 in demulsifying crude oil emulsion.

10. According to the application of the multi-branched ionic liquid demulsifier in demulsifying crude oil emulsion described in claim 9, characterized in that the concentration of the multi-branched ionic liquid demulsifier in the crude oil emulsion is 100-250mg / L, the demulsification temperature is 50-70°C, and the demulsification time is 1-2h.

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