Polymeric Anti-wax pour-point depressant and preparation method therefor

Abstract

The present invention relates to the field of oil and gas field chemistry, and in particular to a polymeric anti-wax pour-point depressant and a preparation method therefor. The present invention discloses a polymeric anti-wax pour-point depressant. A polymer in the polymeric anti-wax pour-point depressant comprises a structural unit A and a structural unit B, wherein in the structural unit A, R1 is C16-C22 alkyl; and in the structural unit B, R2 is C12-C22 alkyl. The polymeric anti-wax pour-point depressant provided by the present invention requires a small addition amount and shows a good anti-wax effect, and compared with conventional anti-wax agents, the polymeric anti-wax pour-point depressant can effectively inhibit precipitation of high-carbon-number paraffins in crude oil, greatly mitigates blockage of crude oil wellbores and transportation pipelines caused by paraffin deposition in crude oil, and has low construction costs and a simple field construction process.

Description

Polymer anti-wax pour point depressant and its preparation method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese Patent Application No. 202410493116.7, filed on April 23, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of oil and gas field chemistry, specifically to a polymer anti-wax pour point depressant and its preparation method. Background Technology

[0004] Most oilfields in my country produce crude oil with high wax content and high pour points. High-wax crude oil, due to its high pour point, high wax content, and high viscosity, is not only detrimental to oil and gas development but also puts significant pressure on crude oil transportation, refining, and storage. Crystallization, cross-linking, and precipitation of wax are very common in petroleum. Throughout the processing, temperature, pressure, and flow conditions are constantly changing. When these conditions change, the wax precipitation process of crude oil also changes. As the temperature gradually decreases to a certain value, large amounts of paraffin wax begin to crystallize, grow, and connect. Then, the wax crystals slowly aggregate, and when the quantity reaches a certain level, a spatial network structure appears, eventually clogging crude oil transportation pipelines, leading to factory shutdowns and increased extraction and transportation costs.

[0005] Among existing oilfield wax removal and prevention technologies, chemical wax removal and prevention technology is simple to operate and inexpensive. Chemical wax removers and preventives include four categories: oil-based wax removers and preventives, water-based wax removers and preventives, emulsion-type wax removers and preventives, and solid wax preventives.

[0006] Oil-based wax removers are highly efficient but toxic, while water-based wax removers are less toxic but have poor wax removal effects. Emulsion-type wax removers combine the advantages of oil-based and water-based wax removers, but they require strict preparation and storage conditions, have poor stability, and are prone to stratification during practical applications, making large-scale on-site promotion impossible. Solid-type wax removers mainly serve as anti-wax agents. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of poor wax prevention and pour point depressant effects, poor pour point depressant effects, and high toxicity of common oil-based wax inhibitors and pour point depressants. For oil wells with different salinity and different temperatures, this invention provides a polymer wax inhibitor and pour point depressant that is stable in storage, easy to use, neutral in nature, does not corrode oil pipes, has good wax prevention and pour point depressant effects, low toxicity, and is simple to prepare.

[0008] This invention provides a polymer anti-waxing and pour point depressant, wherein the polymer in the polymer anti-waxing and pour point depressant contains structural unit A and structural unit B:

[0009] In structural unit A, R1 is an alkyl group of C16 to C22;

[0010] In structural unit B, R2 is an alkyl group of C12 to C22.

[0011] The polymer anti-wax pour point depressant provided by this invention can effectively reduce the pour point of crude oil, enhance the fluidity of crude oil, and has an adjustable carbon chain length, making it particularly suitable for high carbon number paraffin wax.

[0012] The polymer anti-wax and pour point depressant provided by this invention has dual functions of anti-wax and pour point depressant. The product is neutral, does not corrode oil pipes, is stable in storage, and is easy to use.

[0013] A second aspect of the present invention provides a method for preparing the aforementioned polymer anti-waxing and depressant, comprising the following steps:

[0014] A nitrogen-containing compound is added to polymer P containing structural units A and C. After a contact reaction, structural unit C is partially or completely modified to obtain structural unit B, thus obtaining the polymer anti-wax and de-condensing agent. The nitrogen-containing compound has the structural formula: R2-HN2.

[0015] In the formula, R2 is an alkyl group of C12 to C22.

[0016] In structural unit A, R1 is an alkyl group of C16 to C22;

[0017] In structural unit B, R2 is an alkyl group of C12 to C22.

[0018] This invention utilizes nitrogen-containing compounds with C12 to C22 alkyl side chains. The main chain or side chain of the nitrogen-containing compound molecule has a structure and polar groups similar to those of paraffin molecules. The paraffin-like structure in the molecule can form a eutectic with the paraffin molecules. The polar groups in the molecule cause the formed crystal nuclei to be distorted and deformed, which is not conducive to the growth of wax crystals. Therefore, it can more effectively solve the problem of crude oil waxing.

[0019] A third aspect of the present invention provides a polymer anti-wax depressant prepared by the preparation method described herein.

[0020] The polymer anti-wax pour point depressant provided by this invention can effectively inhibit the crystallization of wax in crude oil on the pipe wall or oil rod, destroy the crystal structure of wax crystals, reduce the inter-crystal spacing between wax crystals, reduce the wax crystal content per unit volume of crude oil, reduce the contact between crystal surfaces and crude oil, and prevent wax crystals from forming a three-dimensional network structure. At the same time, it can adhere to the surface of wax crystal particles, prevent wax crystals from agglomerating and growing, and allow wax crystal particles to be dispersed in crude oil and carried out of the oil well in a timely manner.

[0021] The polymer anti-wax pour point depressant provided by this invention requires a small dosage and has a good anti-wax effect. Compared with conventional anti-wax agents, it can effectively inhibit the precipitation of high-carbon paraffin in crude oil, greatly reduce the blockage of crude oil wellbore and transportation pipeline by crude oil wax deposition, and has low construction cost and simple on-site construction process. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] This invention provides a polymer anti-waxing and pour point depressant, wherein the polymer in the polymer anti-waxing and pour point depressant contains structural unit A and structural unit B:

[0024] In structural unit A, R1 is an alkyl group of C16 to C22;

[0025] In structural unit B, R2 is an alkyl group of C12 to C22.

[0026] According to a preferred embodiment of the present invention, in structural unit A, R1 is a straight-chain alkyl group of C16 to C22.

[0027] According to a preferred embodiment of the present invention, in structural unit B, R2 is a straight-chain alkyl group of C12 to C22.

[0028] According to a preferred embodiment of the present invention, in structural unit A, R1 is a C16 straight-chain alkyl, a C18 straight-chain alkyl, or a C22 straight-chain alkyl.

[0029] According to a preferred embodiment of the present invention, in structural unit B, R2 is a C12 straight-chain alkyl, a C16 straight-chain alkyl, a C18 straight-chain alkyl, or a C22 straight-chain alkyl.

[0030] In this invention, there are no special requirements for the molar ratio of structural unit A and structural unit B. According to a preferred embodiment of this invention, the molar ratio of structural unit A and structural unit B is (1-5):1.

[0031] In this invention, there are no special requirements for the molecular weight of the polymer. According to a preferred embodiment of this invention, the number average molecular weight of the polymer is 5000-50000 g / mol.

[0032] The polymer in the polymer anti-wax and pour point depressant of this invention is a random copolymer. One structural formula is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the polymer in the polymer anti-wax and pour point depressant has the following structural formula:

[0033] In structural unit A, R1 is an alkyl group of C16 to C22;

[0034] In structural unit B, R2 is an alkyl group of C12 to C22.

[0035] The molar ratio of structural unit A to structural unit B is m:n = (1-5):1.

[0036] In this invention, there are no special requirements for the molecular weight of the polymer. According to a preferred embodiment of this invention, the number average molecular weight of the polymer is 5000-50000 g / mol.

[0037] According to a preferred embodiment of the present invention, the polymer anti-wax and depressant contains the structural unit A and the structural unit B, and optionally contains one or more of the structural units C, D, and E:

[0038] The polymer in the polymer anti-wax depressant of the present invention is a random copolymer. There are no special requirements for the combination of structural units A, B, C, D and E. Structural units A, B, C, D and E can be arranged arbitrarily.

[0039] In this invention, according to a preferred embodiment, the molar ratio of structural unit A, structural unit B and structural unit C, and structural unit D and structural unit E is (1-5):1:(1-3):1.

[0040] In this invention, according to a preferred embodiment, the molar content of structural unit B is 50-100% and the molar content of structural unit C is 0-50%, based on the total molar content of structural unit B and structural unit C.

[0041] According to a preferred embodiment of the present invention, the number-average molecular weight of the polymer is 5000-50000 g / mol.

[0042] According to a preferred embodiment of the present invention, the polymer anti-wax depressant contains the structural unit A, the structural unit B, the structural unit C, the structural unit D, and the structural unit E.

[0043] The molar ratio of structural unit A, structural unit B and structural unit C, structural unit D and structural unit E is (1~5):1:(1~3):1.

[0044] In this invention, according to a preferred embodiment, the molar content of structural unit B is 50-90% and the molar content of structural unit C is 10-50%, based on the total molar content of structural unit B and structural unit C.

[0045] In this invention, according to a preferred embodiment, the number-average molecular weight of the polymer is 5000-50000 g / mol.

[0046] The polymer in the polymer anti-wax and pour point depressant of this invention is a random copolymer. One structural formula is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the polymer in the polymer anti-wax and pour point depressant has the following structural formula:

[0047] In structural unit A, R1 is an alkyl group of C16 to C22;

[0048] In structural unit B, R2 is an alkyl group from C12 to C22;

[0049] The molar ratio of structural unit A, structural unit B and structural unit C, structural unit D and structural unit E is a:(b+c):d:e=(1~5):1:(1~3):1.

[0050] In this invention, according to a preferred embodiment, the molar content of structural unit B is 50-90% and the molar content of structural unit C is 10-50%, based on the total molar content of structural unit B and structural unit C.

[0051] In this invention, according to a preferred embodiment, the number-average molecular weight of the polymer is 5000-50000 g / mol.

[0052] This invention provides a method for preparing the polymer anti-waxing and decondensing agent of this invention, comprising the following steps:

[0053] A nitrogen-containing compound is added to polymer P containing structural unit A and structural unit C. After a contact reaction, structural unit C is partially or completely modified to obtain structural unit B, thus obtaining the polymer anti-wax and depressant. When the nitrogen-containing compound is in sufficient quantity, structural unit C is completely modified to obtain structural unit B; when the nitrogen-containing compound is insufficient, structural unit C is partially modified to obtain structural unit B.

[0054] The structural formula of the nitrogen-containing compound is: R2-HN2

[0055] In the formula, R2 is an alkyl group of C12 to C22.

[0056] In structural unit A, R1 is an alkyl group of C16 to C22;

[0057] In structural unit B, R2 is an alkyl group of C12 to C22.

[0058] According to a preferred embodiment of the present invention, in the nitrogen-containing compound, R2 is a straight-chain alkyl group of C12 to C22.

[0059] According to a preferred embodiment of the present invention, in structural unit A, R1 is a straight-chain alkyl group of C16 to C22.

[0060] According to a preferred embodiment of the present invention, in structural unit B, R2 is a straight-chain alkyl group of C12 to C22.

[0061] According to a preferred embodiment of the present invention, in structural unit A, R1 is a C16 straight-chain alkyl, a C18 straight-chain alkyl, or a C22 straight-chain alkyl.

[0062] According to a preferred embodiment of the present invention, in structural unit B, R2 is a C12 straight-chain alkyl, a C16 straight-chain alkyl, a C18 straight-chain alkyl, or a C22 straight-chain alkyl.

[0063] According to a preferred embodiment of the present invention, the nitrogen-containing compound is one or more selected from dodecylamine, hexadecylamine, octadecylamine, and docosamine. The objective of the present invention can be achieved using any of the aforementioned nitrogen-containing compounds.

[0064] The molar ratio of the nitrogen-containing compound to the structural unit C in polymer P is not particularly required as long as the purpose of the present invention can be achieved. An exemplary embodiment is described, but this does not limit the scope of the present invention. For example, the molar ratio of the nitrogen-containing compound to the structural unit C in polymer P is (0.5-1.5):1.

[0065] In this invention, the contact conditions are not particularly limited, and conventional conditions in the art are acceptable. This is an illustrative example, but it does not limit the scope of the invention. According to one embodiment of the invention, the contact conditions include: being carried out in a nitrogen atmosphere, and / or at room temperature, for example, a contact temperature of 5-35°C, and / or at atmospheric pressure. The contact time can be determined according to actual needs, for example, until the reaction produces a pale yellow and transparent solution.

[0066] In this invention, polymer P is typically prepared using appropriate monomers. The preparation of polymer P and the contact reaction between polymer P and nitrogen-containing compounds can be carried out in situ in a single batch, which is simple to operate and has obvious advantages.

[0067] In this invention, there are no special requirements for the preparation method of polymer P containing structural unit A and structural unit C. Commonly used polymer preparation methods can be used in this invention. One embodiment is illustrated by way of example, but it does not limit the scope of the invention. In the presence of an initiator, monomer raw materials containing alkyl acrylate, maleic anhydride, and optionally butyl methacrylate and N-vinylcaprolactam are polymerized in a solvent.

[0068] Specifically, in a nitrogen atmosphere, monomeric raw materials containing alkyl acrylate, maleic anhydride, and optionally butyl methacrylate and N-vinylcaprolactam are added to a solvent and mixed to obtain a mixed solution. Then, an initiator is added, the temperature is raised to 70-90°C, and the reaction is carried out for 4-8 hours at atmospheric pressure.

[0069] In this invention, the range of types of alkyl acrylates is relatively wide. According to a preferred embodiment of this invention, the alkyl acrylate is one or more of hexadecyl acrylate, octadecyl acrylate, and dodecyl acrylate. By adopting the aforementioned technical solution, long carbon chains and ester groups are introduced, which can form a eutectic with paraffin wax, change the crystal structure of paraffin wax, and thus achieve the effect of preventing wax from solidifying and reducing solidification.

[0070] In this invention, the amounts of alkyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam can be determined according to actual needs, as long as the objective of this invention is achieved.

[0071] According to a preferred embodiment of the present invention, the molar ratio of alkyl acrylate to maleic anhydride is (1-5):1. By adopting the aforementioned technical solution, the long carbon chain has a structure and polar groups similar to those in paraffin molecules, which can form a eutectic and prevent large amounts of paraffin from precipitating out.

[0072] According to a preferred embodiment of the present invention, the molar ratio of alkyl acrylate, maleic anhydride, butyl methacrylate and N-vinylcaprolactam is (1-5):1:(1-3):1. The wax-depressing agent prepared by the aforementioned technical solution has the dual functions of wax prevention and depressing.

[0073] In this invention, any conventional solvent can be used, and there are no special requirements for the type of solvent. According to a preferred embodiment of this invention, the solvent is selected from one or more of toluene, xylene, and acetone.

[0074] In this invention, there are no special requirements for the amount of solvent used. According to a preferred embodiment of this invention, the content of the solvent in the mixed solution of monomer raw material and solvent is 50-80 wt%.

[0075] In this invention, the range of types of initiators is relatively wide. According to one embodiment of this invention, the initiator is benzoyl peroxide.

[0076] In this invention, there are no special requirements for the amount of initiator. According to a preferred embodiment of the invention, the amount of initiator added is 0.1 to 1 wt% of the total mass of the mixed solution.

[0077] This invention provides a polymer anti-wax depressant prepared by the preparation method described herein.

[0078] The polymer anti-wax pour point depressant of this invention can effectively inhibit the crystallization of wax in crude oil on the pipe wall or oil rod, destroy the crystal structure of wax crystals, reduce the inter-crystal spacing between wax crystals, reduce the wax crystal content per unit volume of crude oil, reduce the contact between crystal surfaces and crude oil, and prevent wax crystals from forming a three-dimensional network structure. At the same time, it can adhere to the surface of wax crystal particles, prevent wax crystals from agglomerating and growing, and allow wax crystal particles to be dispersed in crude oil and carried out of the oil well in a timely manner.

[0079] The polymer anti-wax pour point depressant of this invention requires a small dosage and has a good anti-wax effect. Compared with conventional anti-wax agents, it can effectively inhibit the precipitation of high-carbon paraffin in crude oil, greatly reduce the blockage of crude oil wellbore and transportation pipeline by crude oil wax deposition, and has low construction cost and simple on-site construction process.

[0080] The polymer anti-wax pour point depressant of this invention can effectively reduce the pour point of crude oil, enhance the fluidity of crude oil, and has an adjustable carbon chain length, making it particularly suitable for high carbon number paraffin wax.

[0081] The present invention will be described in detail below through examples.

[0082] This invention is not limited to the following embodiments; specific implementation methods can be determined based on the technical solution of this invention and actual circumstances. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are publicly available chemical reagents and chemical products in the prior art.

[0083] Experimental methods not specified in the examples are generally performed under standard conditions and as described in the manual, or as recommended by the manufacturer; the general equipment, materials, reagents, etc. used are commercially available unless otherwise specified.

[0084] Unless otherwise specified, the pressure in the following examples and comparative examples is atmospheric pressure, the percentage content is weight percentage, and the modification of nitrogen-containing compounds is carried out at room temperature (25°C).

[0085] Example 1

[0086] A mixed solution was obtained by dissolving hexadecyl acrylate and maleic anhydride in xylene, with the xylene content being 50 wt% and the molar ratio of hexadecyl acrylate to maleic anhydride being 1:1. Benzoyl peroxide (BPO) was added as an initiator in a nitrogen atmosphere, at a dosage of 0.1% of the total mass of the mixed solution. After reacting at 70°C for 4 hours, dodecylamine was added for modification, with the molar ratio of dodecylamine to maleic anhydride being 1:1. The reaction continued until a pale yellow, transparent solution was obtained, thus yielding the polymer anti-wax and pour point depressant. The polymer in the anti-wax and pour point depressant contains the following structural units:

[0087] In structural unit A, R1 is hexadecyl; in structural unit B, R2 is dodecyl.

[0088] The molar ratio of structural unit A to structural unit B is 1:1, and the number-average molecular weight of the polymer is 5000 g / mol.

[0089] Example 2

[0090] Octadecyl acrylate and maleic anhydride were dissolved in xylene to obtain a mixed solution. The xylene content in the mixed solution was 60 wt%, and the molar ratio of octadecyl acrylate to maleic anhydride was 2:1. Benzoyl peroxide (BPO) was added as an initiator in a nitrogen atmosphere at a concentration of 0.5% of the total mass of the mixed solution. After reacting at 80°C for 6 hours, hexadecylamine was added for modification. The molar ratio of hexadecylamine to maleic anhydride was 1:1. The reaction continued until a pale yellow transparent solution was obtained, thus yielding the polymer anti-wax and pour point depressant. The polymer in the anti-wax and pour point depressant contains the following structural units:

[0091] In structural unit A, R1 is octadecyl; in structural unit B, R2 is hexadecyl.

[0092] The molar ratio of structural unit A to structural unit B is 2:1, and the number-average molecular weight of the polymer is 10000 g / mol.

[0093] Example 3

[0094] A mixed solution was obtained by dissolving docosyl acrylate and maleic anhydride in xylene, with the xylene content being 70 wt% and the molar ratio of docosyl acrylate to maleic anhydride being 3:1. Benzoyl peroxide (BPO), an initiator, was added at 1% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 90°C for 8 hours, octadecylamine was added for modification, with the molar ratio of octadecylamine to maleic anhydride being 1.5:1, until a pale yellow transparent solution was obtained. This yielded the anti-wax and pour point depressant, a polymer containing the following structural units:

[0095] In structural unit A, R2 is a docosyl group; in structural unit B, R2 is an octadecyl group.

[0096] The molar ratio of structural unit A to structural unit B is 3:1, and the number-average molecular weight of the polymer is 15000 g / mol.

[0097] Example 4

[0098] A mixed solution was obtained by dissolving docosyl acrylate and maleic anhydride in xylene, with xylene comprising 80 wt% and a molar ratio of docosyl acrylate to maleic anhydride of 4:1. Benzoyl peroxide (BPO), an initiator, was added at 1% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 90°C for 8 hours, docosylamine was added for modification, with a molar ratio of docosylamine to maleic anhydride of 1.5:1, until a pale yellow transparent solution was obtained. This yielded the anti-wax and pour point depressant, a polymer containing the following structural units:

[0099] In structural unit A, R1 is a docosyl group; in structural unit B, R2 is a docosyl group.

[0100] The molar ratio of structural unit A to structural unit B is 4:1, and the number-average molecular weight of the polymer is 20,000 g / mol.

[0101] Example 5

[0102] A mixed solution was obtained by dissolving docosyl acrylate and maleic anhydride in xylene, with the xylene content being 80 wt% and the molar ratio of docosyl acrylate to maleic anhydride being 5:1. Benzoyl peroxide (BPO), an initiator, was added at 1% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 90°C for 8 hours, docosylamine was added for modification, with the molar ratio of docosylamine to maleic anhydride being 1.5:1. The reaction continued until a pale yellow, transparent solution was obtained, thus yielding the polymer anti-wax and pour point depressant. The polymer in the anti-wax and pour point depressant contains the following structural units:

[0103] In structural unit A, R1 is a docosyl group; in structural unit B, R2 is a docosyl group.

[0104] The molar ratio of structural unit A to structural unit B is 5:1, and the number-average molecular weight of the polymer is 20,000 g / mol.

[0105] Example 6

[0106] A mixed solution was prepared by dissolving hexadecyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam in xylene. The xylene content in the mixed solution was 50 wt%, and the molar ratio of hexadecyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam was 1:1:1:1. Benzoyl peroxide (BPO), an initiator, was added at 0.1% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 70°C for 4 hours, dodecylamine was added for modification. The molar ratio of dodecylamine to maleic anhydride was 0.5:1. The reaction continued until a pale yellow, transparent solution was obtained, thus yielding the polymer anti-wax and pour point depressant. The polymer in the anti-wax and pour point depressant contains the following structural units:

[0107] In structural unit A, R1 is hexadecyl; in structural unit B, R2 is dodecyl.

[0108] The molar ratio of structural unit A, structural unit B, structural unit C, structural unit D, and structural unit E is 1:0.5:0.5:1:1, and the number-average molecular weight of the polymer is 30000 g / mol.

[0109] Example 7

[0110] Octadecyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam were dissolved in xylene to obtain a mixed solution. The xylene content in the mixed solution was 60 wt%, and the molar ratio of octadecyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam was 2:1:2:1. Benzoyl peroxide (BPO), an initiator, was added at 0.5% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 80°C for 6 hours, hexadecylamine was added for modification. The molar ratio of hexadecylamine to maleic anhydride was 1:1. The reaction continued until a pale yellow, transparent solution was obtained, thus yielding the polymeric anti-wax and pour point depressant. The polymeric anti-wax and pour point depressant contains the following structural units:

[0111] In structural unit A, R1 is octadecyl; in structural unit B, R2 is hexadecyl.

[0112] The molar ratio of structural unit A, structural unit B, structural unit D, and structural unit E is 2:1:2:1, and the number-average molecular weight of the polymer is 40,000 g / mol.

[0113] Example 8

[0114] A mixed solution was prepared by dissolving docosyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam in xylene, with the xylene content being 70 wt%. The molar ratio of docosyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam was 3:1:3:1. Benzoyl peroxide (BPO), an initiator, was added at 1% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 90°C for 8 hours, octadecylamine was added for modification, with the molar ratio of octadecylamine to maleic anhydride being 1.5:1. The reaction continued until a pale yellow transparent solution was obtained, thus yielding the polymer anti-wax and pour point depressant. The polymer in the anti-wax and pour point depressant contains the following structural units:

[0115] In structural unit A, R1 is docosyl; in structural unit B, R2 is octadecyl.

[0116] The molar ratio of structural unit A, structural unit B, structural unit D, and structural unit E is 3:1:3:1, and the number-average molecular weight of the polymer is 50,000 g / mol.

[0117] Example 9

[0118] A mixed solution was prepared by dissolving docosyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam in xylene. The xylene content in the mixed solution was 80 wt%, and the molar ratio of docosyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam was 4:1:3:1. Benzoyl peroxide (BPO), an initiator, was added at 1% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 90°C for 8 hours, docosylamine was added for modification. The molar ratio of docosylamine to maleic anhydride was 1.5:1. The reaction continued until a pale yellow, transparent solution was obtained, thus yielding the polymer anti-wax and pour point depressant. The polymer in the anti-wax and pour point depressant contains the following structural units:

[0119] In structural unit A, R1 is a docosyl group; in structural unit B, R2 is a docosyl group.

[0120] The molar ratio of structural unit A, structural unit B, structural unit D, and structural unit E is 4:1:3:1, and the number-average molecular weight of the polymer is 50,000 g / mol.

[0121] Example 10

[0122] A mixed solution was prepared by dissolving docosyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam in xylene, with the xylene content being 80 wt%. The molar ratio of docosyl acrylate, maleic anhydride, butyl methacrylate, and N-vinylcaprolactam was 5:1:3:1. Benzoyl peroxide (BPO), an initiator, was added at 1% of the total mass of the mixed solution under nitrogen atmosphere. After reacting at 90°C for 8 hours, docosylamine was added for modification, with the molar ratio of docosylamine to maleic anhydride being 1.5:1. The reaction continued until a pale yellow transparent solution was obtained, thus yielding the polymer anti-wax and pour point depressant. The polymer in the anti-wax and pour point depressant contains the following structural units:

[0123] In structural unit A, R1 is a docosyl group; in structural unit B, R2 is a docosyl group.

[0124] The molar ratio of structural unit A, structural unit B, structural unit D, and structural unit E is 5:1:3:1, and the number-average molecular weight of the polymer is 50,000 g / mol.

[0125] Comparative Example 1

[0126] Following the method of Example 3, except that vinyl acetate was used instead of docosyl acrylate, comparative sample 1 was obtained.

[0127] Comparative Example 2

[0128] Following the method of Example 3, except that styrene was used instead of maleic anhydride to obtain Comparative Sample 2.

[0129] Test case

[0130] The wax inhibition rate and pour point reduction of the polymers in Examples 1-10 and Comparative Examples 1-2 were determined. The wax inhibition rate of the wax inhibitors and pour point depressants was evaluated according to the standard SYT 6300-2009 "Technical Conditions for Wax Inhibitors for Oil Production". The effect of the wax inhibitors and pour point depressants on reducing the pour point of crude oil was evaluated according to the Chinese petroleum and natural gas industry standard SY / T 0541-94 "Determination of Pour Point of Crude Oil". British crude oil was used for evaluation. The carbon number distribution of the paraffin wax was C10-C40. The carbon number distribution of the paraffin wax in this crude oil was mostly concentrated below C35, and high carbon number paraffin wax accounted for about 15%. The test results are as follows:

[0131] Table 1. Wax prevention rate of polymer wax inhibitors and pour point depressants

[0132] Table 2. Pour Point Depression Values ​​of Wax Inhibitors and Pour Point Depressants

[0133] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A polymer anti-waxing and depressant, characterized in that, The polymer in this anti-wax and depressant contains structural unit A and structural unit B: In structural unit A, R1 is an alkyl group of C16 to C22; In structural unit B, R2 is an alkyl group of C12 to C22.

2. The polymer anti-waxing and depressant according to claim 1, characterized in that, In structural unit A, R1 is a C16–C22 straight-chain alkyl group; and / or In structural unit B, R2 is a straight-chain alkyl group of C12 to C22.

3. The polymer anti-waxing and depressant according to claim 1, characterized in that, In structural unit A, R1 is a C16 straight-chain alkyl group, a C18 straight-chain alkyl group, or a C22 straight-chain alkyl group; and / or In structural unit B, R2 is a C12 straight-chain alkyl, a C16 straight-chain alkyl, a C18 straight-chain alkyl, or a C22 straight-chain alkyl.

4. The polymer anti-waxing and depressant according to any one of claims 1-3, characterized in that, The molar ratio of structural unit A to structural unit B is (1-5):1; and / or The number-average molecular weight of the polymer is 5000-50000 g / mol.

5. The polymer anti-waxing and depressant according to any one of claims 1-4, characterized in that, The polymer anti-wax and pour point depressant contains structural unit A and structural unit B, and optionally contains one or more of structural units C, D, and E: Among them, structural unit A, structural unit B, structural unit C, structural unit D, and structural unit E can be arranged arbitrarily.

6. The polymer anti-waxing and depressant according to claim 5, characterized in that, In this polymer anti-wax and pour point depressant, the molar ratio of structural unit A, the sum of structural unit B and structural unit C, and structural unit D and structural unit E is (1-5):1:(1-3):1; and / or Based on the total molar content of structural unit B and structural unit C, the molar content of structural unit B is 50-100%, and the molar content of structural unit C is 0-50%; and / or The number-average molecular weight of the polymer is 5000-50000 g / mol.

7. The polymer anti-waxing and depressant according to any one of claims 1-6, characterized in that, The polymer anti-wax and depressant contains the aforementioned structural unit A, structural unit B, structural unit C, structural unit D, and structural unit E.

8. The polymer anti-waxing and depressant according to claim 7, characterized in that, In this polymer anti-wax and pour point depressant, the molar ratio of structural unit A, the sum of structural unit B and structural unit C, and structural unit D and structural unit E is (1-5):1:(1-3):1; and / or Based on the total molar content of structural unit B and structural unit C, the molar content of structural unit B is 50-90%, and the molar content of structural unit C is 10-50%; and / or The number-average molecular weight of the polymer is 5000-50000 g / mol.

9. A method for preparing a polymer anti-waxing and depressant, characterized in that, It includes the following steps: A nitrogen-containing compound is added to polymer P containing structural units A and C. After a contact reaction, structural unit C is partially or completely modified to obtain structural unit B, thus obtaining the polymer anti-wax and depressant. The structural formula of the nitrogen-containing compound is: R2-HN2 In the formula, R2 is a C12 to C22 alkyl group; In structural unit A, R1 is an alkyl group of C16 to C22; In structural unit B, R2 is an alkyl group of C12 to C22.

10. The method for preparing the polymer anti-waxing and depressant according to claim 9, characterized in that, In nitrogen-containing compounds, R2 is a C12–C22 straight-chain alkyl group; and / or In structural unit A, R1 is a C16–C22 straight-chain alkyl group; and / or In structural unit B, R2 is a straight-chain alkyl group of C12 to C22.

11. The method for preparing the polymer anti-waxing and depressant according to claim 9 or 10, characterized in that, In structural unit A, R1 is a C16 straight-chain alkyl, a C18 straight-chain alkyl, or a C22 straight-chain alkyl; In structural unit B, R2 is a C12 straight-chain alkyl, a C16 straight-chain alkyl, a C18 straight-chain alkyl, or a C22 straight-chain alkyl.

12. The preparation method according to any one of claims 9-11, characterized in that, The nitrogen-containing compound is one or more of dodecylamine, hexadecylamine, octadecylamine, and diethylamine.

13. The preparation method according to any one of claims 9-12, characterized in that, The molar ratio of the nitrogen-containing compound to the structural unit C in polymer P is (0.5-1.5):1; and / or The conditions for a contact reaction include: The experiment shall be conducted in a nitrogen atmosphere and / or at a temperature of 5-35°C and / or at atmospheric pressure.

14. The preparation method according to any one of claims 9-13, characterized in that, The preparation steps of polymer P containing structural unit A and structural unit C include: In the presence of an initiator, a monomeric raw material containing alkyl acrylate, maleic anhydride, and optionally butyl methacrylate and N-vinylcaprolactam is polymerized in a solvent. Preferably, the polymerization conditions include: being carried out in a nitrogen atmosphere, and / or at a temperature of 70–90°C, and / or for 4–8 hours, and / or at atmospheric pressure.

15. The preparation method according to claim 14, characterized in that, The alkyl acrylate is one or more of hexadecyl acrylate, octadecyl acrylate, and docosyl acrylate.

16. The preparation method according to claim 14, characterized in that, The solvent is selected from one or more of toluene, xylene, and acetone; and / or The amount of solvent used is 50-80 wt% of the total mass of the mixed solution of monomer raw material and solvent.

17. The preparation method according to claim 14, characterized in that, The initiator is benzoyl peroxide; and / or The amount of initiator added is 0.1-1 wt% of the total mass of the mixed solution.

18. The polymer anti-wax depressant prepared by the preparation method according to any one of claims 9-17.

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