Oil-soluble demulsifier for heavy oil fields and preparation method thereof

Abstract

The present invention belongs to the technical field of oilfield additives, and specifically relates to an oil-soluble demulsifier for heavy oil fields and a preparation method thereof. The oil-soluble demulsifier for heavy oil fields provided by the present invention is prepared from a block polymer emulsion, nonylphenol polyoxyethylene ether, modified nanoparticles, and a crosslinking agent. In the present invention, methoxystyrene, dodecyl vinyl ether, N,N-dimethylaminopropyl acrylamide, and 2-acrylamide-2-methylpropane sulfonic acid are used to prepare a quaternary block comb polymer, which is crosslinked with the nonylphenol polyoxyethylene ether at the molecular level by a crosslinking agent, and nano-modified particles are added to enable the prepared demulsifier to be rapidly adsorbed on the oil-water interface, and to separately adsorb the oil phase and the water phase, thereby reducing the oil-water interfacial tension, achieving rapid separation of the oil phase and the water phase, and improving the demulsification performance.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield additives, and particularly relates to an oil-soluble demulsifier for heavy oil fields and a preparation method thereof. Background Art

[0002] 80% of the heavy oil mined exists in the form of emulsion. Due to the high density and viscosity of heavy crude oil, as well as the high content of surfactants such as asphaltenes and colloids, the interfacial film formed is strong. Therefore, reducing the viscosity of heavy oil and breaking the oil-water emulsion have become one of the important issues in the petrochemical industry.

[0003] Due to the complex composition of heavy oil, current methods for reducing viscosity and breaking emulsions are mostly chemical. Common viscosity reducers include ethylene-vinyl acetate copolymer, styrene-maleic anhydride-acrylic acid higher alcohol ester copolymer, and alkylphenol polyoxyethylene ether. Common demulsifiers include polyethers, polyquaternary ammonium salts, and copolymers. However, most of these demulsifiers suffer from high toxicity, high dosage, poor stability, and poor applicability. Common demulsifiers are polyether-based block polymers composed of ethylene oxide and propylene oxide. However, the storage of epoxy compounds such as ethylene oxide and propylene oxide requires pressure reaction equipment, which increases the cost of demulsifier synthesis. Therefore, the development of new environmentally friendly and high-performance demulsifiers and viscosity reducers is highly necessary.

[0004] A Chinese patent application document with application publication number CN118165272A discloses a method for preparing a broad-spectrum crude oil demulsifier. Specifically, the method comprises: preparing a first-generation branched polymer using ethylenediamine and methyl acrylate, reacting the first-generation branched polymer with a monomer or a branching unit, and purifying the second-generation branched polymer. The second-generation branched polymer is further reacted with a monomer or a branching unit, and purified to obtain a third-generation branched polymer. The third-generation branched polymer is further reacted with a monomer or a branching unit, and purified to obtain a fourth-generation branched polymer. The fourth-generation branched polymer is dispersed, emulsified, moistened, defoamed, and adhered using a solvent to obtain a viscous liquid demulsifier. Finally, the demulsifier is mixed with an acrylic ester copolymer emulsion, and an initiator is added to prepare the demulsifier. The demulsifier obtained by this method is grafted with ethylene oxide propylene oxide block polyether to prepare a multi-branched crude oil demulsifier, which can effectively improve the demulsifier's dehydration effect. However, the demulsifier molecules prepared by this method are difficult to quickly diffuse to the oil-water interface at low temperatures, resulting in a poor demulsification effect and a reduced dehydration rate. At the same time, the synthesis process of this demulsifier is cumbersome and the yield is low, so the synthesis cost is high. Summary of the Invention

[0005] In order to solve the technical problems pointed out in the above-mentioned prior art that oil-soluble demulsifiers require large dosage, poor demulsification effect and high cost, the present invention provides an oil-based demulsifier for heavy oil fields and a preparation method thereof.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] An oil-soluble demulsifier for heavy oil fields comprises the following components in parts by weight:

[0008] 35-40 parts of block polymer emulsion, 10-15 parts of nonylphenol polyoxyethylene ether, 18-23 parts of modified nanoparticles, and 8-12 parts of crosslinking agent;

[0009] The block polymer emulsion is prepared by adding deionized water, an emulsifier, p-methoxystyrene and dodecyl vinyl ether into a reaction kettle, heating the mixture to 85-90° C., adding an initiator, a catalyst, N,N-dimethylaminopropyl acrylamide and 2-acrylamide-2-methylpropanesulfonic acid under stirring, carrying out the reaction at the temperature for 4-5 hours, and performing reduced pressure distillation to obtain the block polymer emulsion.

[0010] In the present invention, a tetrablock polymer prepared by emulsion polymerization of methoxystyrene, dodecyl vinyl ether, N,N-dimethylaminopropyl acrylamide, and 2-acrylamide-2-methylpropane sulfonic acid under the action of an initiator and a catalyst, and nonylphenol polyoxyethylene ether are used as main components of the oil-soluble demulsifier. The methoxyphenyl group in the side chain of the tetrablock polymer molecular structure can increase the aromaticity of the polymer, and the dodecyl ether group has good flexibility and low cohesive energy, thereby improving the hydrophobicity of the polymer. The secondary amino group, tertiary amino group, sulfonic acid group and other groups in the side chain structure have strong polarity and extremely strong interaction with the water phase in the heavy oil. They can quickly penetrate the oil phase, enter the water phase, be adsorbed on the surface of water droplets, and attract surrounding water droplets to collide and gather together. Finally, they settle and separate under the action of the oil-water density difference, thereby realizing a demulsification and dehydration process of rapid viscosity reduction and oil-water separation, thereby improving the demulsification efficiency. The block polymer prepared by the present invention has a side chain structure of varying lengths. When the demulsifier molecules with a comb-like structure diffuse into the emulsion droplets and penetrate the water droplet protective layer, they are easily adsorbed on the surface of solid particles and water droplets, reducing their surface energy, changing the surface wettability, destroying the contact between particles on the protective layer, reducing the strength of the interfacial film and causing it to be destroyed. At the same time, the block polymer molecules can be preferentially and quickly adsorbed on the oil-water interface, reducing the oil-water interfacial tension and achieving rapid demulsification.

[0011] Furthermore, the present invention adds modified nanoparticles to the demulsifier formula, boasting small size, large specific surface area, good dispersibility, and ease of modification. These nanoparticles can penetrate the stacked structure of heavy oil and fully contact the oil, further enhancing the demulsification efficiency of the demulsifier. The addition of a crosslinking agent allows molecular crosslinking of the block polymer and nonylphenol polyoxyethylene ether, extending the demulsifier's molecular chain and increasing its molecular weight. This, in turn, reduces the strength of the oil-water interface film and improves demulsification performance.

[0012] Preferably, the weight parts of the components in the preparation method of the block polymer are: 60-70 parts of deionized water, 5-10 parts of emulsifier, 13-18 parts of p-methoxystyrene, 6-10 parts of dodecyl vinyl ether, 5-10 parts of initiator, 3-5 parts of catalyst, 9-12 parts of N,N-dimethylaminopropyl acrylamide, and 6-10 parts of 2-acrylamide-2-methylpropanesulfonic acid.

[0013] Preferably, the emulsifier in the preparation method of the block polymer is sodium lauryl sulfate or alkylphenol polyoxyethylene ether.

[0014] In the preparation process of the block polymer, sodium lauryl sulfate or alkylphenol polyoxyethylene ether is added as an emulsifier to reduce the surface tension of the oil-water interface, forming a stable emulsion. A protective film is formed in the emulsion to prevent particle aggregation or sedimentation, effectively ensuring the stable polymerization of the block polymer.

[0015] Preferably, in the method for preparing the block polymer, the initiator consists of ammonium persulfate and sodium bisulfite in a mass ratio of 3.1-3.5:1.

[0016] Preferably, in the method for preparing the block polymer, the catalyst is p-toluenesulfonic acid.

[0017] Preferably, the preparation method of the modified nanoparticles is: add myristic acid to water, heat to 80-90°C, stir until the myristic acid is dissolved, add sodium hydroxide, stir evenly, add nano-aluminum hydroxide, stir for 2-3 hours, filter, dry, and grind to obtain modified nanoparticles.

[0018] In the present invention, myristic acid is used to modify nano-aluminum hydroxide. Myristic acid can form a bond with the aluminum in the nano-aluminum hydroxide through electrostatic attraction, coating the nano-aluminum hydroxide with the myristic acid, imparting good hydrophobicity, interfacial compatibility, and dispersibility to the modified nano-aluminum hydroxide. The modified nano-aluminum hydroxide has a large specific surface area and stronger adsorption capacity, allowing it to disperse more quickly to the oil-water interface of heavy oil, achieving rapid demulsification. Furthermore, the modified nano-aluminum hydroxide contains abundant active hydroxyl groups on its surface, which can interact with polar groups in the colloid and asphalt in the heavy oil, disrupting intermolecular hydrogen bonds, inhibiting the aggregation and entanglement of the colloid and asphalt, and reducing the size of the aggregates, thereby reducing the viscosity of the heavy oil.

[0019] More preferably, in the preparation method of the modified nanoparticles, the mass ratio of myristic acid to sodium hydroxide is 5.2-5.7:1.

[0020] More preferably, in the preparation method of the modified nanoparticles, the mass of myristic acid is 2.7%-3.1% of the mass of the nano-aluminum hydroxide.

[0021] In the preparation process of modified nanoparticles, although myristic acid can improve the hydrophobicity of nano-aluminum hydroxide and improve its dispersibility, the dosage of myristic acid also has an important influence on the modification effect. When the dosage is too small, the nano-aluminum hydroxide cannot be coated and the hydrophobic property cannot be improved. As the dosage of myristic acid increases, it forms a single-layer coating on the surface of the nano-aluminum hydroxide, exposing the hydrophobic carbon chain to the outside. Continuing to increase the dosage of myristic acid will form a double-layer coating on the surface of the nano-aluminum hydroxide, so that the nano-aluminum hydroxide can restore its hydrophilic properties.

[0022] Preferably, the cross-linking agent is benzoyl peroxide or di-tert-butyl peroxide.

[0023] In the present invention, benzoyl peroxide or di-tert-butyl peroxide is used to establish chemical crosslinking between the block polymer and nonylphenol polyoxyethylene ether, thereby increasing the molecular weight and interfacial activity of the demulsifier, allowing it to be better adsorbed on the oil-water interface, destroying the oil-water interface film, and achieving rapid demulsification.

[0024] The present invention also provides a method for preparing the oil-soluble demulsifier for heavy oil fields, comprising the following steps:

[0025] S1: Dissolve nonylphenol polyoxyethylene ether in tetrahydrofuran and heat to 60-65°C to obtain solution I;

[0026] S2: Add a crosslinking agent to the solution I obtained in step S1, stir evenly, and add the block polymer emulsion while stirring. Heat to 85-90°C, react for 5.5-6 hours, and cool to obtain solution II;

[0027] S3: adding the modified nanoparticles to the solution II obtained in step S2, stirring evenly, and removing tetrahydrofuran by distillation under reduced pressure to obtain an oil-soluble demulsifier for heavy oil fields.

[0028] By adopting the above technical solution, nonylphenol polyoxyethylene ether and block polymer are cross-linked at the molecular level, the molecular chain of the demulsifier is extended, and it is uniformly mixed with the modified nanoparticles, so that the prepared oil-soluble demulsifier for heavy oil fields has a good demulsification effect.

[0029] Compared with the prior art, the oil-soluble demulsifier for heavy oil fields and the preparation method thereof provided by the present invention have the following technical advantages:

[0030] (1) The present invention uses methoxystyrene, dodecyl vinyl ether, N,N-dimethylaminopropyl acrylamide, and 2-acrylamide-2-methylpropanesulfonic acid to prepare a quaternary block comb polymer, which can be preferentially and rapidly adsorbed on the oil-water interface, reducing the oil-water interfacial tension and achieving rapid demulsification;

[0031] (2) In the present invention, myristic acid is used to modify nano-aluminum hydroxide, which gives the modified nano-aluminum hydroxide good hydrophobicity, interfacial compatibility and dispersibility, reduces the viscosity of heavy oil, and improves demulsification performance;

[0032] (3) In the present invention, a cross-linking agent is added to cross-link the block polymer and nonylphenol polyoxyethylene ether at the molecular level, so that the demulsifier molecular chain is extended and the molecular weight is increased, thereby reducing the strength of the oil-water interface film and improving the demulsification performance. DETAILED DESCRIPTION

[0033] The following will be further described in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Those skilled in the art can make various modifications based on the basic concept of the present invention, but as long as they do not deviate from the basic concept of the present invention, they are all within the scope of the present invention.

[0034] Example 1

[0035] An oil-soluble demulsifier for heavy oil fields comprises the following components in parts by weight:

[0036] 35g block polymer emulsion, 15g nonylphenol polyoxyethylene ether, 18g modified nanoparticles, 8g benzoyl peroxide;

[0037] The block polymer emulsion was prepared by adding 70g of deionized water, 5g of sodium lauryl sulfate, 13g of p-methoxystyrene, and 6g of dodecyl vinyl ether to a reactor, heating to 85°C. Then, while stirring, 5g of initiator, 3g of p-toluenesulfonic acid, 9g of N,N-dimethylaminopropylacrylamide, and 6g of 2-acrylamide-2-methylpropanesulfonic acid were added. The reaction was maintained at this temperature for 4 hours, and then vacuum distillation was performed to obtain the block polymer emulsion. The initiator consisted of ammonium persulfate and sodium bisulfite in a mass ratio of 3.1:1.

[0038] The preparation method of the modified nanoparticles is as follows: 5.2g of myristic acid is added to 100g of water, heated to 80°C, stirred until the myristic acid is dissolved, 1g of sodium hydroxide is added, stirred evenly, 192.6g of nano-aluminum hydroxide is added, stirred for 2h, filtered, dried, and ground to obtain modified nanoparticles.

[0039] The preparation method of an oil-soluble demulsifier for heavy oil fields comprises the following steps:

[0040] S1: Dissolve nonylphenol polyoxyethylene ether in 50 g of tetrahydrofuran and heat to 60° C. to obtain solution I;

[0041] S2: Add a crosslinking agent to the solution I obtained in step S1, stir evenly, and add the block polymer emulsion while stirring. Heat to 85°C, react for 5.5 hours, and cool to obtain solution II.

[0042] S3: adding the modified nanoparticles to the solution II obtained in step S2, stirring evenly, and removing tetrahydrofuran by distillation under reduced pressure to obtain an oil-soluble demulsifier for heavy oil fields.

[0043] Example 2

[0044] An oil-soluble demulsifier for heavy oil fields comprises the following components in parts by weight:

[0045] 40g block polymer emulsion, 10g nonylphenol polyoxyethylene ether, 23g modified nanoparticles, 12g di-tert-butyl peroxide;

[0046] The block polymer emulsion was prepared by adding 60g of deionized water, 10g of alkylphenol polyoxyethylene ether, 18g of p-methoxystyrene, and 10g of dodecyl vinyl ether to a reactor, heating to 90°C. While stirring, 10g of initiator, 5g of p-toluenesulfonic acid, 12g of N,N-dimethylaminopropyl acrylamide, and 10g of 2-acrylamide-2-methylpropanesulfonic acid were added. The reaction was maintained at this temperature for 5 hours, and then vacuum distillation was performed to obtain the block polymer emulsion. The initiator was composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3.5:1.

[0047] The preparation method of the modified nanoparticles is as follows: 5.7 g of myristic acid is added to water, heated to 90°C, stirred until the myristic acid is dissolved, 1 g of sodium hydroxide is added, stirred evenly, 183.8 g of nano-aluminum hydroxide is added, stirred for 2.5 hours, filtered, dried, and ground to obtain modified nanoparticles.

[0048] The preparation method of an oil-soluble demulsifier for heavy oil fields comprises the following steps:

[0049] S1: Dissolve nonylphenol polyoxyethylene ether in 50 g of tetrahydrofuran and heat to 65°C to obtain solution I;

[0050] S2: Add a crosslinking agent to the solution I obtained in step S1, stir evenly, and add the block polymer emulsion while stirring. Heat to 90°C, react for 6 hours, and cool to obtain solution II;

[0051] S3: adding the modified nanoparticles to the solution II obtained in step S2, stirring evenly, and removing tetrahydrofuran by distillation under reduced pressure to obtain an oil-soluble demulsifier for heavy oil fields.

[0052] Example 3

[0053] An oil-soluble demulsifier for heavy oil fields comprises the following components in parts by weight:

[0054] 38g block polymer emulsion, 13g nonylphenol polyoxyethylene ether, 20g modified nanoparticles, 10g di-tert-butyl peroxide;

[0055] The block polymer emulsion was prepared by adding 67g of deionized water, 8g of sodium lauryl sulfate, 15g of p-methoxystyrene, and 8g of dodecyl vinyl ether to a reactor, heating to 88°C. Then, while stirring, 9g of initiator, 4g of p-toluenesulfonic acid, 10g of N,N-dimethylaminopropylacrylamide, and 8g of 2-acrylamide-2-methylpropanesulfonic acid were added. The mixture was kept warm for 4.2 hours, and then distilled under reduced pressure to obtain the block polymer emulsion. The initiator consisted of ammonium persulfate and sodium bisulfite in a mass ratio of 3.3:1.

[0056] The preparation method of the modified nanoparticles is as follows: 5.5g of myristic acid is added to water, heated to 86°C, stirred until the myristic acid is dissolved, 1g of sodium hydroxide is added, stirred evenly, 189.7g of nano-aluminum hydroxide is added, stirred for 2.5h, filtered, dried, and ground to obtain modified nanoparticles.

[0057] The preparation method of an oil-soluble demulsifier for heavy oil fields comprises the following steps:

[0058] S1: Dissolve nonylphenol polyoxyethylene ether in 50 g of tetrahydrofuran and heat to 63°C to obtain solution I;

[0059] S2: Add a crosslinking agent to the solution I obtained in step S1, stir evenly, and add the block polymer emulsion while stirring. Heat to 88°C, react for 5.8 hours, and cool to obtain solution II.

[0060] S3: adding the modified nanoparticles to the solution II obtained in step S2, stirring evenly, and removing tetrahydrofuran by distillation under reduced pressure to obtain an oil-soluble demulsifier for heavy oil fields.

[0061] Comparative Example 1

[0062] The formula, preparation method and preparation method of the oil-soluble demulsifier in this comparative example are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: 82g of deionized water, 8g of sodium lauryl sulfate and 8g of dodecyl vinyl ether are added to a reactor, heated to 88°C, 9g of initiator, 4g of p-toluenesulfonic acid, 10g of N,N-dimethylaminopropyl acrylamide and 8g of 2-acrylamide-2-methylpropanesulfonic acid are added under stirring, the reaction is kept warm for 4.2h, and the block polymer emulsion is obtained by vacuum distillation. The initiator consists of ammonium persulfate and sodium bisulfite in a mass ratio of 3.3:1. That is, the difference between this comparative example and Example 3 is that an equal amount of deionized water is used instead of p-methoxystyrene in the preparation method of the block polymer emulsion in this comparative example.

[0063] Comparative Example 2

[0064] The formula, preparation method and preparation method of the oil-soluble demulsifier and the modified nanoparticles in this comparative example are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: 75g of deionized water, 8g of sodium lauryl sulfate and 15g of p-methoxystyrene are added to a reactor, heated to 88°C, 9g of initiator, 4g of p-toluenesulfonic acid, 10g of N,N-dimethylaminopropyl acrylamide and 8g of 2-acrylamide-2-methylpropanesulfonic acid are added under stirring, the reaction is kept warm for 4.2h, and the block polymer emulsion is obtained by vacuum distillation. The initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3.3:1. That is, the difference between this comparative example and Example 3 is that an equal amount of deionized water is used instead of dodecyl vinyl ether in this comparative example.

[0065] Comparative Example 3

[0066] The formula, preparation method, and preparation method of the oil-soluble demulsifier and modified nanoparticles in this comparative example are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: 77g of deionized water, 8g of sodium lauryl sulfate, 15g of p-methoxystyrene, and 8g of dodecyl vinyl ether are added to a reactor, heated to 88°C, 9g of initiator, 4g of p-toluenesulfonic acid, and 8g of 2-acrylamide-2-methylpropanesulfonic acid are added under stirring, the reaction is kept warm for 4.2h, and the block polymer emulsion is obtained by vacuum distillation. The initiator consists of ammonium persulfate and sodium bisulfite in a mass ratio of 3.3:1. That is, the difference between this comparative example and Example 3 is that an equal amount of deionized water is used instead of N,N-dimethylaminopropyl acrylamide in this comparative example.

[0067] Comparative Example 4

[0068] The formula, preparation method and preparation method of the oil-soluble demulsifier in this comparative example are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: 75g of deionized water, 8g of sodium lauryl sulfate, 15g of p-methoxystyrene and 8g of dodecyl vinyl ether are added to a reactor, heated to 88°C, 9g of initiator, 4g of p-toluenesulfonic acid and 10g of N,N-dimethylaminopropyl acrylamide are added under stirring, the reaction is kept warm for 4.2h, and vacuum distillation is performed to obtain a block polymer emulsion. The initiator consists of ammonium persulfate and sodium bisulfite in a mass ratio of 3.3:1. That is, the difference between this comparative example and Example 3 is that an equal amount of deionized water is used instead of 2-acrylamide-2-methylpropanesulfonic acid in this comparative example.

[0069] Comparative Example 5

[0070] The preparation methods of the block polymer emulsion and the oil-soluble demulsifier in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that an equal amount of nano-aluminum hydroxide is used instead of modified nanoparticles in this comparative example.

[0071] Comparative Example 6

[0072] The preparation methods of the block polymer emulsion and the oil-soluble demulsifier in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that an equal amount of nano-calcium carbonate is used instead of nano-aluminum hydroxide in the preparation method of the modified nanoparticles in this comparative example.

[0073] Comparative Example 7

[0074] The preparation method of the block polymer emulsion in the oil-soluble demulsifier and the preparation method of the oil-soluble demulsifier in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that in the preparation method of the modified nanoparticles in this comparative example, the mass of myristic acid is 15 g, and the mass of nano-aluminum hydroxide is 189.7 g, that is, the mass of myristic acid is 7.9% of the mass of nano-aluminum hydroxide.

[0075] Test example

[0076] The crude oil in this test example was selected from Karamay Oilfield, and the dosage of the demulsifier was 120 mg / L.

[0077] Dehydration Rate Testing: Dehydration rates were tested for the demulsifiers prepared in Examples 1-3 and Comparative Examples 1-7 according to SY / T 5281-2000, "Test Methods for Performance of Crude Oil Demulsifiers - Bottle Test Method," and the water separation was recorded. After water separation, the water content of the heavy oil was tested according to GB / T 8929-2006, "Determination of Water Content in Crude Oil - Distillation Method." The test results are shown in Table 1.

[0078] Table 1 Performance test results

[0079]

[0080] As shown in Table 1, the dehydration rate of the oil-soluble demulsifier for heavy oil fields provided by the present invention reached 95%-98% within 90 minutes, and the oil-water interface was neat, the water phase was clear, and the water content of the upper oil phase was reduced to 0.3%-0.6%. This shows that the oil-soluble demulsifier for heavy oil fields provided by the present invention has a good dehydration effect. Among them, the oil-soluble demulsifier for heavy oil fields prepared in Example 3 had the highest dehydration rate and the lowest water content of the upper oil phase, which is the best embodiment of the present invention.

[0081] Compared with Example 3, in the preparation method of the block polymer emulsion of Comparative Example 1, an equal amount of deionized water is used instead of p-methoxystyrene, in the preparation method of the block polymer emulsion of Comparative Example 2, an equal amount of deionized water is used instead of dodecyl vinyl ether, in the preparation method of the block polymer emulsion of Comparative Example 3, an equal amount of deionized water is used instead of N,N-dimethylaminopropyl acrylamide, and in the preparation method of the block polymer emulsion of Comparative Example 4, an equal amount of deionized water is used instead of 2-acrylamide-2-methylpropanesulfonic acid. However, the dehydration rate of the obtained oil-soluble demulsifier is reduced to varying degrees, and the water content of the upper oil phase is increased to varying degrees. This shows that the use of methoxystyrene, dodecyl vinyl ether, N,N-dimethylaminopropyl acrylamide, and 2-acrylamide-2-methylpropanesulfonic acid in the present invention all plays an important role in the block polymer, and the four together improve the dehydration rate of the oil-soluble demulsifier; in Comparative Example 5, the nanoparticles are not modified, but the dehydration rate of the obtained oil-soluble demulsifier is reduced, and The oil-water interface is turbid and the water content of the upper oil phase increases. This is because the nanoparticles are not modified and are unevenly dispersed in the system, and because only a small part of the unmodified nanoparticles are dispersed to the oil-water interface, the demulsification effect deteriorates; Comparative Example 6 uses an equal amount of nano-calcium carbonate instead of nano-aluminum hydroxide, but the dehydration rate of the obtained oil-soluble demulsifier is reduced, and the water content of the upper oil phase increases, which shows that not all nanoparticles can play the role of nano-aluminum hydroxide. It is speculated that the modification of nano-calcium carbonate by myristic acid affects the Zeta of nano-calcium carbonate, causing the coating of nano-calcium carbonate by myristic acid to change, affecting the dehydration rate of the oil-soluble demulsifier; Comparative Example 7 increases the mass ratio of myristic acid and nano-aluminum hydroxide, but the dehydration rate of the obtained oil-soluble demulsifier is reduced, and the water content of the upper oil phase increases. This is because too much myristic acid forms a double-layer coating on the surface of nano-aluminum hydroxide, and nano-aluminum hydroxide restores hydrophilicity, resulting in a decrease in the dehydration rate of the oil-soluble demulsifier.

[0082] The above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Persons skilled in the art should not modify the above embodiments without departing from the spirit and scope of the present invention. Any equivalent modifications or alterations made by persons skilled in the art without departing from the technical spirit of the present invention are intended to fall within the scope of protection of the present invention.

Claims

1. An oil-soluble demulsifier for heavy oil fields, characterized in that: The invention comprises the following components in parts by weight: 35-40 parts of block polymer emulsion, 10-15 parts of nonylphenol polyoxyethylene ether, 18-23 parts of modified nanoparticles, and 8-12 parts of crosslinking agent; The block polymer emulsion is prepared by adding deionized water, an emulsifier, p-methoxystyrene and dodecyl vinyl ether into a reaction kettle, heating to 85-90° C., adding an initiator, a catalyst, N,N-dimethylaminopropyl acrylamide and 2-acrylamide-2-methylpropanesulfonic acid under stirring, keeping the temperature for reaction for 4-5 hours, and performing reduced pressure distillation to obtain the block polymer emulsion; The modified nanoparticles are prepared by adding myristic acid to water, heating to 80-90° C., stirring until the myristic acid dissolves, adding sodium hydroxide, stirring evenly, adding nano-aluminum hydroxide, stirring for 2-3 hours, filtering, drying, and grinding to obtain the modified nanoparticles; wherein the mass of the myristic acid is 2.7%-3.1% of the mass of the nano-aluminum hydroxide.

2. The oil-soluble demulsifier for heavy oil fields according to claim 1, characterized in that: The weight proportions of the components in the block polymer preparation method are: 60-70 parts of deionized water, 5-10 parts of emulsifier, 13-18 parts of p-methoxystyrene, 6-10 parts of dodecyl vinyl ether, 5-10 parts of initiator, 3-5 parts of catalyst, 9-12 parts of N,N-dimethylaminopropyl acrylamide, and 6-10 parts of 2-acrylamide-2-methylpropanesulfonic acid.

3. The oil-soluble demulsifier for heavy oil fields according to claim 1, characterized in that: The emulsifier in the preparation method of the block polymer is sodium lauryl sulfate or alkylphenol polyoxyethylene ether.

4. The oil-soluble demulsifier for heavy oil fields according to claim 1, characterized in that: In the preparation method of the block polymer, the initiator is composed of ammonium persulfate and sodium bisulfite in a mass ratio of 3.1-3.5:

1.

5. The oil-soluble demulsifier for heavy oil fields according to claim 1, characterized in that: The catalyst in the preparation method of the block polymer is p-toluenesulfonic acid.

6. The oil-soluble demulsifier for heavy oil fields according to claim 1, characterized in that: In the preparation method of the modified nanoparticles, the mass ratio of myristic acid to sodium hydroxide is 5.2-5.7:

1.

7. The oil-soluble demulsifier for heavy oil fields according to claim 1, characterized in that: The cross-linking agent is benzoyl peroxide or di-tert-butyl peroxide.

8. The method for preparing an oil-soluble demulsifier for heavy oil fields according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Dissolve nonylphenol polyoxyethylene ether in tetrahydrofuran and heat to 60-65°C to obtain solution I; S2: adding a crosslinking agent to the solution I obtained in step S1, stirring evenly, and adding the block polymer emulsion under stirring, heating to 85-90°C, reacting for 5.5-6 hours, and cooling to obtain a solution II; S3: adding the modified nanoparticles to the solution II obtained in step S2, stirring evenly, and removing tetrahydrofuran by distillation under reduced pressure to obtain an oil-soluble demulsifier for heavy oil fields.

Images