Oil-soluble demulsifier for heavy oil field and preparation method of oil-soluble demulsifier

Abstract

The invention belongs to the technical field of oilfield auxiliaries, and particularly relates to an oil-soluble demulsifier for a heavy oil field and a preparation method of the oil-soluble demulsifier. The oil-soluble demulsifier for the heavy oil field, provided by the invention, is prepared from a block polymer emulsion, nonylphenol polyoxyethylene ether, modified nanoparticles and a cross-linking agent. According to the invention, methoxystyrene, dodecyl vinyl ether, N, N-dimethylaminopropyl acrylamide and 2-acrylamide-2-methylpropanesulfonic acid are adopted to prepare a quaternary block comb-shaped polymer, the quaternary block comb-shaped polymer and nonylphenol polyoxyethylene ether are subjected to molecular-level cross-linking through a cross-linking agent, nano modified particles are added, and the quaternary block comb-shaped polymer is prepared. The prepared demulsifier can be rapidly adsorbed on an oil-water interface and respectively adsorb an oil phase and a water phase, so that the tension of the oil-water interface is reduced, rapid separation of the oil phase and the water phase is realized, and the demulsification performance is improved.

Description

Technical Field

[0001] The present 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 extracted heavy oil exists in the form of emulsion. Due to the high density and viscosity of heavy crude oil, and the high content of interfacial active substances such as asphaltene and resin, the formed interfacial film is firm. Therefore, the viscosity reduction of heavy oil and the demulsification of oil-water emulsion have become one of the important topics in the petrochemical industry.

[0003] Due to the complex composition of heavy oil, at present, chemical methods are mostly used for viscosity reduction and demulsification of heavy oil. Common viscosity reducers include ethylene-vinyl acetate copolymer, styrene-maleic anhydride-high carbon alcohol acrylate multi-component copolymer, alkylphenol polyoxyethylene ether, etc. Common demulsifiers include polyethers, polyquaternary ammonium salts, copolymers, etc. However, most of them have problems such as high toxicity, large dosage, poor stability and applicability. The commonly used demulsifier is a polyether-type demulsifier mainly composed of a block polymer with ethylene oxide and propylene oxide as monomers. However, due to the storage of epoxides such as ethylene oxide and propylene oxide requiring pressure reaction equipment, the synthesis cost of the demulsifier increases. Therefore, it is very necessary to develop new environmentally friendly and high-performance demulsifiers and viscosity reducers.

[0004] The Chinese patent application document with the application publication number CN118165272A discloses a preparation method of a broad-spectrum crude oil demulsifier, specifically: preparing a first-generation branched polymer from ethylenediamine and methyl acrylate, reacting with a monomer or a branching unit, purifying to obtain a second-generation branched polymer, continuing to react with a monomer or a branching unit, purifying to obtain a third-generation branched polymer, and then continuing to react with a monomer or a branching unit, purifying to obtain a fourth-generation branched polymer. Dispersing, emulsifying, wetting, defoaming and adhering the fourth-generation branched polymer with a solvent to obtain a viscous liquid demulsifying dry agent, and finally mixing it with an acrylate copolymer emulsion and adding an initiator to prepare the demulsifier. The demulsifier obtained by this method is grafted with ethylene oxide-propylene oxide block polyether, and a multi-branched crude oil demulsifier is prepared, which can effectively improve the dehydration effect of the demulsifier. However, the demulsifier molecules prepared by this method are difficult to quickly diffuse to the oil-water interface at low temperature, resulting in poor demulsification effect and 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 of large dosage, poor demulsification effect and high cost of the oil-soluble demulsifier pointed out in the above-mentioned prior art, the present invention provides an oil-soluble demulsifier for heavy oil fields and a preparation method thereof.

[0006] To achieve the above object, the technical solution of the present invention is as follows: An oil-soluble demulsifier for heavy oil fields, comprising 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 preparation method of the block polymer emulsion is as follows: Deionized water, emulsifier, p-methoxystyrene and dodecyl vinyl ether are added to a reaction kettle, heated to 85-90 °C, and an initiator, catalyst, N,N-dimethylaminopropyl acrylamide and 2-acrylamide-2-methylpropanesulfonic acid are added under stirring, and the reaction is carried out under insulation for 4-5 h, and then vacuum distilled to obtain a block polymer emulsion.

[0007] In the present invention, a quaternary block polymer prepared by emulsion polymerization of p-methoxystyrene, dodecyl vinyl ether, N,N-dimethylaminopropyl acrylamide, and 2-acrylamide-2-methylpropanesulfonic acid under the action of an initiator and a catalyst and nonylphenol polyoxyethylene ether are used as the main components of the oil-soluble demulsifier. Among them, the methoxyphenyl group in the side chain of the quaternary block polymer molecular structure can increase the aromaticity of the polymer, and the dodecyl ether group has good flexibility and low cohesive energy, which can improve the hydrophobicity of the polymer; groups such as secondary amino group, tertiary amino group, and sulfonic acid group in the side chain structure have strong polarity and extremely strong interaction with the water phase in heavy oil. It can quickly penetrate the oil phase into the water phase and adsorb on the surface of water droplets, and attract the surrounding water droplets to collide and gather together. Finally, under the action of the oil-water density difference, it settles and separates, realizing the demulsification dehydration process of rapid viscosity reduction and oil-water separation, and improving the demulsification efficiency. The block polymer prepared by the present invention has a side chain structure with different lengths. When the demulsifier molecules with a comb-like structure diffuse and penetrate through the water droplet protection layer to the emulsion droplets, they are easily adsorbed on the surface of solid particles and water droplets, reducing their surface energy, changing the surface wetting performance, destroying the contact between particles on the protection layer, reducing the strength of the interfacial film and destroying it. At the same time, the block polymer molecules can preferentially and quickly adsorb on the oil-water interface, reducing the oil-water interface tension and realizing rapid demulsification.

[0008] In addition, the present invention adds modified nanoparticles with the characteristics of small size, large specific surface area, good dispersion performance, and easy modification to the demulsifier formula. It can enter the interior of the heavy oil stacking structure, make full contact with the heavy oil, and further improve the demulsification efficiency of the demulsifier. Adding a crosslinking agent to crosslink the block polymer and nonylphenol polyoxyethylene ether at the molecular level can extend the molecular chain of the demulsifier and increase the molecular weight, thereby reducing the strength of the oil-water interfacial film and improving the demulsification performance.

[0009] Preferably, the weight parts of each component in the preparation method of the block polymer are as follows: deionized water 60 - 70 parts, emulsifier 5 - 10 parts, p-methoxystyrene 13 - 18 parts, dodecyl vinyl ether 6 - 10 parts, initiator 5 - 10 parts, catalyst 3 - 5 parts, N,N-dimethylaminopropyl acrylamide 9 - 12 parts, 2-acrylamide-2-methylpropanesulfonic acid 6 - 10 parts.

[0010] Preferably, in the preparation method of the block polymer, the emulsifier is sodium dodecyl sulfate or alkylphenol polyoxyethylene ether.

[0011] In the preparation process of the block polymer of the present invention, adding sodium dodecyl sulfate or alkylphenol polyoxyethylene ether as an emulsifier can reduce the surface tension at the oil-water interface, form a stable emulsion state, form a protective film in the emulsion, prevent particle aggregation or sedimentation, and effectively ensure the stable polymerization of the block polymer.

[0012] Preferably, in the preparation method of the block polymer, the initiator is composed of ammonium persulfate and sodium bisulfite according to a mass ratio of 3.1 - 3.5:1.

[0013] Preferably, in the preparation method of the block polymer, the catalyst is p-toluenesulfonic acid.

[0014] Preferably, the preparation method of the modified nanoparticles is as follows: Add myristic acid to water, heat to 80 - 90 °C, stir until the myristic acid dissolves, add sodium hydroxide, stir evenly, add nano-aluminum hydroxide, stir for 2 - 3 h, then filter by suction, dry, and grind to obtain the modified nanoparticles.

[0015] In the present invention, myristic acid is selected to modify nano-aluminum hydroxide. Myristic acid can bond with aluminum in nano-aluminum hydroxide through electrostatic attraction, so that myristic acid is coated on nano-aluminum hydroxide, endowing the modified nano-aluminum hydroxide with good hydrophobicity, interfacial compatibility and dispersibility. The modified nano-aluminum hydroxide has a large specific surface area and stronger adsorption ability, can be more quickly dispersed to the oil-water interface of heavy oil to achieve the effect of rapid demulsification, and its surface contains abundant active hydroxyl groups, which can interact with polar groups in resins and asphaltenes in heavy oil, break intermolecular hydrogen bonds, inhibit the aggregation and entanglement of resins and asphaltenes, and reduce the size of aggregates, thereby reducing the viscosity of heavy oil.

[0016] 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.

[0017] More preferably, in the preparation method of the modified nanoparticles, the mass of myristic acid is 2.7% - 3.1% of the mass of nano-aluminum hydroxide.

[0018] In the preparation process of the modified nanoparticles, although myristic acid can improve the hydrophobicity of nano-aluminum hydroxide and enhance its dispersibility, the dosage of myristic acid also has an important impact 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, a monolayer coating is formed on the surface of the nano-aluminum hydroxide, exposing the hydrophobic carbon chains outside. Continuing to increase the dosage of myristic acid will form a bilayer coating on the surface of the nano-aluminum hydroxide, restoring the hydrophilic property of the nano-aluminum hydroxide.

[0019] Preferably, the cross-linking agent is benzoyl peroxide or di-tert-butyl peroxide.

[0020] In the present invention, the selection of benzoyl peroxide or di-tert-butyl peroxide can establish chemical cross-linking between the block polymer and nonylphenol polyoxyethylene ether, increase the molecular weight of the demulsifier and the interfacial activity of the demulsifier, enable it to better adsorb on the oil-water interface, destroy the oil-water interfacial film, and achieve rapid demulsification.

[0021] The present invention also provides a preparation method of the oil-soluble demulsifier for viscous oil fields, comprising the following steps: S1: Dissolve nonylphenol polyoxyethylene ether in tetrahydrofuran and heat to 60 - 65 °C to obtain Solution I; S2: Add a cross-linking agent to Solution I obtained in step S1, stir evenly, and add a block polymer emulsion under stirring, raise the temperature to 85 - 90 °C, react for 5.5 - 6 h, and cool to obtain Solution II; S3: Add modified nanoparticles to Solution II obtained in step S2, stir evenly, and remove tetrahydrofuran by vacuum distillation to obtain an oil-soluble demulsifier for viscous oil fields.

[0022] By adopting the above technical solution, molecular-level cross-linking of nonylphenol polyoxyethylene ether and block polymer is achieved, the molecular chain of the demulsifier is extended, and uniform mixing with the modified nanoparticles is realized, so that the prepared oil-soluble demulsifier for viscous oil fields has good demulsification effect.

[0023] Compared with the prior art, the oil-soluble demulsifier for viscous oil fields provided by the present invention and its preparation method have the following technical advantages: (1) In the present invention, a quaternary block comb-shaped polymer is prepared by using methoxystyrene, dodecyl vinyl ether, N,N-dimethylaminopropyl acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid, which can preferentially and rapidly adsorb on the oil-water interface, reduce the oil-water interfacial tension, and achieve rapid demulsification; (2) In the present invention, myristic acid is selected to modify nano-aluminum hydroxide, endowing the modified nano-aluminum hydroxide with good hydrophobicity, interfacial compatibility, and dispersibility, reducing the viscosity of viscous oil, and improving the demulsification performance; (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 molecular chain of the demulsifier is extended and the molecular weight is increased, thereby reducing the strength of the oil-water interfacial film and improving the demulsification performance. Detailed implementation manners

[0024] The following will further illustrate with specific examples, but the present invention is not limited to the following examples. Those skilled in the art can make various modifications according to the basic idea of the present invention, but as long as they do not depart from the basic idea of the present invention, they are within the scope of the present invention.

[0025] Example 1 An oil-soluble demulsifier for heavy oil fields comprises the following components in parts by weight: 35 g of block polymer emulsion, 15 g of nonylphenol polyoxyethylene ether, 18 g of modified nanoparticles, 8 g of benzoyl peroxide; The preparation method of the block polymer emulsion is as follows: Add 70 g of deionized water, 5 g of sodium dodecyl sulfate, 13 g of p-methoxystyrene and 6 g of dodecyl vinyl ether into a reaction kettle, heat to 85 °C, add 5 g of initiator, 3 g of p-toluenesulfonic acid, 9 g of N,N-dimethylaminopropyl acrylamide and 6 g of 2-acrylamide-2-methylpropanesulfonic acid under stirring, keep the temperature for reaction for 4 h, and carry out vacuum distillation to obtain the block polymer emulsion. The initiator is composed of ammonium persulfate and sodium bisulfite according to a mass ratio of 3.1:1.

[0026] The preparation method of the modified nanoparticles is as follows: Add 5.2 g of myristic acid into 100 g of water, heat to 80 °C, stir until the myristic acid is dissolved, add 1 g of sodium hydroxide, stir evenly, add 192.6 g of nanoaluminum hydroxide, stir for 2 h, then filter, dry and grind to obtain the modified nanoparticles.

[0027] The preparation method of the oil-soluble demulsifier for heavy oil fields comprises the following steps: S1: Dissolve nonylphenol polyoxyethylene ether in 50 g of tetrahydrofuran, heat to 60 °C to obtain solution I; S2: Add a cross-linking agent to the solution I obtained in step S1, stir evenly, and add the block polymer emulsion under stirring, heat up to 85 °C, react for 5.5 h, and cool to obtain solution II; S3: Add the modified nanoparticles to the solution II obtained in step S2, stir evenly, and carry out vacuum distillation to remove tetrahydrofuran to obtain the oil-soluble demulsifier for heavy oil fields.

[0028] Example 2 An oil-soluble demulsifier for heavy oil fields comprises the following components in parts by weight: 40 g of block polymer emulsion, 10 g of nonylphenol polyoxyethylene ether, 23 g of modified nanoparticles, 12 g of di-tert-butyl peroxide; The preparation method of the block polymer emulsion is as follows: Add 60 g of deionized water, 10 g of alkylphenol polyoxyethylene ether, 18 g of p-methoxystyrene and 10 g of dodecyl vinyl ether into a reaction kettle, heat to 90 °C, add 10 g of initiator, 5 g of p-toluenesulfonic acid, 12 g of N,N-dimethylaminopropyl acrylamide and 10 g of 2-acrylamido-2-methylpropanesulfonic acid under stirring, keep the temperature for reaction for 5 h, and carry out vacuum distillation to obtain the block polymer emulsion. The initiator is composed of ammonium persulfate and sodium bisulfite according to a mass ratio of 3.5:1.

[0029] The preparation method of the modified nanoparticles is as follows: Add 5.7 g of myristic acid into water, heat to 90 °C, stir until the myristic acid is dissolved, add 1 g of sodium hydroxide, stir evenly, add 183.8 g of nanoaluminum hydroxide, stir for 2.5 h, then carry out suction filtration, drying and grinding to obtain the modified nanoparticles.

[0030] The preparation method of the oil-soluble demulsifier for heavy oil fields includes the following steps: S1: Dissolve nonylphenol polyoxyethylene ether in 50 g of tetrahydrofuran, heat to 65 °C to obtain Solution I; S2: Add a crosslinking agent to Solution I obtained in Step S1, stir evenly, and add the block polymer emulsion under stirring, heat up to 90 °C, react for 6 h, and cool to obtain Solution II; S3: Add the modified nanoparticles to Solution II obtained in Step S2, stir evenly, and carry out vacuum distillation to remove tetrahydrofuran to obtain the oil-soluble demulsifier for heavy oil fields.

[0031] Example 3 An oil-soluble demulsifier for heavy oil fields, comprising the following components in parts by weight: 38 g of block polymer emulsion, 13 g of nonylphenol polyoxyethylene ether, 20 g of modified nanoparticles, 10 g of di-tert-butyl peroxide; The preparation method of the block polymer emulsion is as follows: Add 67 g of deionized water, 8 g of sodium dodecyl sulfate, 15 g of p-methoxystyrene and 8 g of dodecyl vinyl ether into a reaction kettle, heat to 88 °C, add 9 g of initiator, 4 g of p-toluenesulfonic acid, 10 g of N,N-dimethylaminopropyl acrylamide and 8 g of 2-acrylamido-2-methylpropanesulfonic acid under stirring, keep the temperature for reaction for 4.2 h, and carry out vacuum distillation to obtain the block polymer emulsion. The initiator is composed of ammonium persulfate and sodium bisulfite according to a mass ratio of 3.3:1.

[0032] The preparation method of the modified nanoparticles is as follows: Add 5.5 g of myristic acid into water, heat to 86 °C, stir until the myristic acid is dissolved, add 1 g of sodium hydroxide, stir evenly, add 189.7 g of nano-aluminum hydroxide, filter by suction after stirring for 2.5 h, dry, and grind to obtain the modified nanoparticles.

[0033] The preparation method of the oil-soluble demulsifier for heavy oil fields includes the following steps: S1: Dissolve nonylphenol polyoxyethylene ether in 50 g of tetrahydrofuran, heat to 63 °C to obtain Solution I; S2: Add a crosslinking agent to Solution I obtained in Step S1, stir evenly, and add a block polymer emulsion under stirring, heat up to 88 °C, react for 5.8 h, and cool to obtain Solution II; S3: Add the modified nanoparticles to Solution II obtained in Step S2, stir evenly, and remove tetrahydrofuran by vacuum distillation to obtain the oil-soluble demulsifier for heavy oil fields.

[0034] Comparative Example 1 In this comparative example, the formulation, preparation method of the oil-soluble demulsifier, and the preparation method of the modified nanoparticles are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: Add 82 g of deionized water, 8 g of sodium dodecyl sulfate, and 8 g of dodecyl vinyl ether to a reaction kettle, heat to 88 °C, add 9 g of initiator, 4 g of p-toluenesulfonic acid, 10 g of N,N-dimethylaminopropyl acrylamide, and 8 g of 2-acrylamide-2-methylpropanesulfonic acid under stirring, keep the temperature for reaction for 4.2 h, and perform vacuum distillation to obtain the block polymer emulsion. 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 in the preparation method of the block polymer emulsion in this comparative example, an equal amount of deionized water is used to replace p-methoxystyrene.

[0035] Comparative Example 2 In this comparative example, the formulation, preparation method of the oil-soluble demulsifier, and the preparation method of the modified nanoparticles are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: Add 75 g of deionized water, 8 g of sodium dodecyl sulfate, and 15 g of p-methoxystyrene to a reaction kettle, heat to 88 °C, add 9 g of initiator, 4 g of p-toluenesulfonic acid, 10 g of N,N-dimethylaminopropyl acrylamide, and 8 g of 2-acrylamide-2-methylpropanesulfonic acid under stirring, keep the temperature for reaction for 4.2 h, and perform vacuum distillation to obtain the block polymer emulsion. 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 in this comparative example, an equal amount of deionized water is used to replace dodecyl vinyl ether.

[0036] Comparative Example 3 In this comparative example, the formulation of the oil-soluble demulsifier, the preparation method thereof, and the preparation method of the modified nanoparticles are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: 77 g of deionized water, 8 g of sodium dodecyl sulfate, 15 g of p-methoxystyrene, and 8 g of dodecyl vinyl ether are added to a reaction kettle, heated to 88 °C, and 9 g of initiator, 4 g of p-toluenesulfonic acid, and 8 g of 2-acrylamido-2-methylpropanesulfonic acid are added under stirring. The reaction is carried out under insulation for 4.2 h, and then vacuum distillation is carried out to obtain the block polymer emulsion. 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 in this comparative example, an equal amount of deionized water is used to replace N,N-dimethylaminopropyl acrylamide.

[0037] Comparative Example 4 In this comparative example, the formulation of the oil-soluble demulsifier, the preparation method thereof, and the preparation method of the modified nanoparticles are the same as those in Example 3. The preparation method of the block polymer emulsion in this comparative example is as follows: 75 g of deionized water, 8 g of sodium dodecyl sulfate, 15 g of p-methoxystyrene, and 8 g of dodecyl vinyl ether are added to a reaction kettle, heated to 88 °C, and 9 g of initiator, 4 g of p-toluenesulfonic acid, and 10 g of N,N-dimethylaminopropyl acrylamide are added under stirring. The reaction is carried out under insulation for 4.2 h, and then vacuum distillation is carried out to obtain the block polymer emulsion. 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 in this comparative example, an equal amount of deionized water is used to replace 2-acrylamido-2-methylpropanesulfonic acid.

[0038] Comparative Example 5 In this comparative example, the preparation method of the block polymer emulsion in the oil-soluble demulsifier and the preparation method of the oil-soluble demulsifier are similar to those in Example 3. The difference between this comparative example and Example 3 is that in this comparative example, an equal amount of nano-aluminum hydroxide is used to replace the modified nanoparticles.

[0039] Comparative Example 6 In this comparative example, the preparation method of the block polymer emulsion in the oil-soluble demulsifier and the preparation method of the oil-soluble demulsifier 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, an equal amount of nano-calcium carbonate is used to replace nano-aluminum hydroxide.

[0040] Comparative Example 7 In this comparative example, the preparation method of the block polymer emulsion in the oil-soluble demulsifier and the preparation method of the oil-soluble demulsifier 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.

[0041] Test Example In this test example, the crude oil described is selected from the Karamay Oilfield, and the dosage of the demulsifier is 120 mg / L.

[0042] Dehydration rate test: According to SY / T 5281-2000 "Bottle Test Method for Detecting the Performance of Crude Oil Demulsifiers", the demulsifiers prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to dehydration rate tests, and the water separation situation 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.

[0043] Table 1 Performance Test Results

[0044] As can be seen from Table 1, the oil-soluble demulsifier for heavy oil fields provided by the present invention has a dehydration rate of 95%-98% within 90 minutes, and the oil-water interface is neat, the water phase is clear, and the water content of the upper oil phase is reduced to 0.3%-0.6%. This shows that the oil-soluble demulsifier for heavy oil fields provided by the present invention has good dehydration effects. Among them, the demulsifier for heavy oil fields prepared in Example 3 has the highest dehydration rate and the lowest water content in the upper oil phase, which is the best example of the present invention.

[0045] Compared with Example 3, in the preparation method of the block polymer emulsion of Comparative Example 1, an equal amount of deionized water was used to replace p-methoxystyrene; in the preparation method of the block polymer emulsion of Comparative Example 2, an equal amount of deionized water was used to replace dodecyl vinyl ether; in the preparation method of the block polymer emulsion of Comparative Example 3, an equal amount of deionized water was used to replace N,N-dimethylaminopropyl acrylamide; in the preparation method of the block polymer emulsion of Comparative Example 4, an equal amount of deionized water was used to replace 2-acrylamido-2-methylpropanesulfonic acid. However, the dehydration rate of the oil-soluble demulsifier prepared decreased to varying degrees, and the water content in the upper oil phase increased to varying degrees. This indicates that p-methoxystyrene, dodecyl vinyl ether, N,N-dimethylaminopropyl acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid all play important roles in the block polymer in the present invention, and the four of them together improve the dehydration rate of the oil-soluble demulsifier; in Comparative Example 5, the nanoparticles were not modified, but the dehydration rate of the oil-soluble demulsifier prepared decreased, the oil-water interface was turbid, and the water content in the upper oil phase increased. This is because the nanoparticles were not modified and were unevenly dispersed in the system. Moreover, since only a small part of the unmodified nanoparticles were dispersed at the oil-water interface, the demulsification effect became worse; in Comparative Example 6, an equal amount of nano-calcium carbonate was used to replace nano-aluminum hydroxide, but the dehydration rate of the oil-soluble demulsifier prepared decreased, and the water content in the upper oil phase increased. This shows that not all nanoparticles can achieve the same effect as nano-aluminum hydroxide. It is speculated that the modification of nano-calcium carbonate by myristic acid affected the Zeta of nano-calcium carbonate, resulting in a change in the coating of myristic acid on nano-calcium carbonate and affecting the dehydration rate of the oil-soluble demulsifier; in Comparative Example 7, the mass ratio of myristic acid to nano-aluminum hydroxide was increased, but the dehydration rate of the oil-soluble demulsifier prepared decreased, and the water content in the upper oil phase increased. This is because too much myristic acid formed a double-layer coating on the surface of nano-aluminum hydroxide, and nano-aluminum hydroxide restored its hydrophilicity, resulting in a decrease in the dehydration rate of the oil-soluble demulsifier.

[0046] The above embodiments are merely illustrative of the present invention and do not limit the present invention. Those skilled in the art should not modify the above embodiments without departing from the spirit and scope of the present invention. All equivalent modifications or changes made by those with ordinary knowledge in the relevant technical field without departing from the technical idea of the present invention still fall within the protection scope of the present invention.

Claims

1. An oil-soluble demulsifier for heavy oil fields, characterized in that, Comprising 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, 8 - 12 parts of crosslinking agent; The preparation method of the block polymer emulsion is as follows: Add deionized water, emulsifier, p-methoxystyrene and dodecyl vinyl ether into a reaction kettle, heat to 85 - 90 °C, add initiator, catalyst, N,N-dimethylaminopropyl acrylamide and 2-acrylamido-2-methylpropanesulfonic acid under stirring, keep the temperature for reaction for 4 - 5 h, and perform vacuum distillation to obtain the block polymer emulsion.

2. The oil-soluble demulsifier for viscous oil fields according to claim 1, characterized in that, The parts by weight of each component in the preparation method of the block polymer are as follows: 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, 6 - 10 parts of 2-acrylamido-2-methylpropanesulfonic acid.

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

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

1.

5. The oil-soluble demulsifier for viscous 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, The preparation method of the modified nanoparticles is as follows: Add myristic acid into water, heat to 80 - 90 °C, stir until myristic acid is dissolved, add sodium hydroxide, stir evenly, add nano-aluminum hydroxide, stir for 2 - 3 h, then perform suction filtration, drying, and grinding to obtain the modified nanoparticles.

7. The oil-soluble demulsifier for heavy oil fields according to claim 6, 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.

8. The oil-soluble demulsifier for viscous oil fields according to claim 6, characterized in that, In the preparation method of the modified nanoparticles, the mass of myristic acid is 2.7% - 3.1% of the mass of nano-aluminum hydroxide.

9. The oil-soluble demulsifier for heavy oil fields according to claim 1, wherein The crosslinking agent is benzoyl peroxide or di-tert-butyl peroxide.

10. The preparation method of the oil-soluble demulsifier for viscous oil fields according to any one of claims 1-9, characterized in that, Including the following steps: S1: Dissolve nonylphenol polyoxyethylene ether in tetrahydrofuran, heat to 60 - 65 °C to obtain Solution I; S2: Add the crosslinking agent to Solution I obtained in step S1, stir evenly, and add the block polymer emulsion under stirring, raise the temperature to 85 - 90 °C, react for 5.5 - 6 h, and cool to obtain Solution II; S3: Add the modified nanoparticles to Solution II obtained in step S2, stir evenly, perform vacuum distillation to remove tetrahydrofuran to obtain an oil-soluble demulsifier for viscous oil fields.

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