A polyamide-imide paraffin inhibitor, its preparation method and application

Abstract

The application discloses a polyamide-imide paraffin inhibitor and a preparation method and application thereof. The polyamide-imide paraffin inhibitor is prepared from monounsaturated fatty acid and maleic anhydride as raw materials through copolymerization and graft modification. The polyamide-imide paraffin inhibitor is a long-chain fishbone structure, contains certain polar groups on the main chain, and has long alkyl chains with different lengths on both sides. The long alkyl chains on both sides are similar to the structure of paraffin, can be co-crystallized with paraffin, and can inhibit or weaken the crystallization and precipitation of paraffin. The polyamide-imide paraffin inhibitor prepared by the application can form a space net structure in crude oil, can further hinder the contact of paraffin molecules, inhibit the further crystallization and increase of paraffin, and make the paraffin molecules unable to precipitate. The polyamide-imide paraffin inhibitor can be adsorbed on the surface of paraffin crystals, changes the wettability of the paraffin crystals, and makes the paraffin crystals dispersed in the crude oil.

Description

Technical Field

[0001] This invention relates to the field of wax inhibitor preparation technology, specifically to a polyamide-imide wax inhibitor, its preparation method, and its application. Background Technology

[0002] Statistics show that crude oil with a wax content exceeding 10% accounts for approximately 90% of my country's total crude oil production, with most crude oils containing over 20% wax by mass, and some even reaching 45% to 50%. During crude oil extraction, as crude oil flows from the formation into the well and rises to the wellhead, the gradual decrease in formation pressure and temperature, along with the continuous release of lighter components from the crude oil, reduces the solubility of wax. As a result, wax precipitates and deposits in crystal form, adsorbing onto the well casing and other production equipment, leading to a continuous decrease in well production. Wax adsorbed in the oil layer can also damage the reservoir. Furthermore, wax crystallization in pipelines increases crude oil flow resistance, directly affecting production and energy consumption, and in severe cases, causing production shutdowns. Therefore, wax prevention and removal are crucial and frequent tasks in daily oil well management. Reasonable and timely prevention of wax crystallization and extending the wax removal cycle are essential guarantees for normal oil well production.

[0003] Currently, commonly used wax removal and prevention technologies in oilfields mainly include mechanical wax removal, thermal wax removal, surface energy wax prevention, magnetic wax prevention, microbial wax removal, and chemical wax removal. Among these, chemical wax removal is the most widely used, and oil-based, emulsion, and water-based wax removers are the most prevalent. Common wax inhibitors fall into three main categories: polycyclic aromatic hydrocarbons (PAHs), surfactants, and polymers. Polymer wax inhibitors are more widely used in oilfields. Most polymer wax inhibitors are oil-soluble and are branched polymers containing paraffin segments. When used, they are injected into the well and mixed with crude oil. Even at very low concentrations, they form a network structure throughout the crude oil structure. If the crude oil temperature decreases, paraffin precipitates out onto the network, forming a loose, open, dendritic or aggregated dendritic crystalline aggregate that prevents wax deposition, thus preventing wax deposition.

[0004] Polymer-based wax inhibitors, also known as wax crystal modifiers, are oil-soluble comb-like polymers with side chains of a certain length. Their main chain or side chains possess structures and polar groups similar to paraffin molecules. At lower temperatures, their paraffin-like structures form eutectic crystals with paraffin molecules. Due to the presence of polar groups in their molecules, the resulting crystal nuclei are distorted, inhibiting further wax crystal growth. However, currently commonly used wax inhibitors in China have poor wax-preventing effects, especially at low temperatures. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a polyamide-imide wax inhibitor, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A polyamide-imide wax inhibitor, said polyamide-imide wax inhibitor is composed of a polyamide-imide copolymer and an organic solvent;

[0008] The preparation method of the polyamide-imide copolymer includes the following steps: adding monounsaturated fatty acids and maleic anhydride to solvent I, mixing evenly, adding an initiator, heating to 100-150℃ and reacting for 2-10 hours, then adding aliphatic primary amine, condensing agent and activator, reacting at 100-150℃ for 5-12 hours, and after the reaction is completed, removing solvent I to obtain the polyamide-imide copolymer.

[0009] Specifically, the molar ratio of the monounsaturated fatty acid, maleic anhydride, initiator, aliphatic primary amine, condensing agent and activator is 1:1-2:0.0001-0.0005:2-3:1.5-2.5:0.1-0.3.

[0010] Specifically, the monounsaturated fatty acid is selected from one or more of myristoleic acid, palmitoleic acid, oleic acid, ricinoleic acid, and cetearyl acid; the solvent I is selected from one or more of toluene, xylene, and trimethylbenzene; and the aliphatic primary amine is selected from one or more of octylamine, dodecylamine, hexadecylamine, eicosamine, and tetradecylamine.

[0011] Specifically, the initiator is selected from one or more of tert-butyl peroxide, azobisisobutyl cyanide, benzoyl peroxide, cumene hydroperoxide, and diisopropyl peroxide.

[0012] Specifically, the condensing agent is selected from at least one of carbodiimide condensing agents, onium salt condensing agents, and organophosphorus condensing agents.

[0013] More specifically, the carbodiimide condensing agent is dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC), or 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDCI).

[0014] The onium salt condensing agents are O-(7-azabenzotriazol-1-yl)-di(dimethylamino)carbomony hexafluorophosphate (HATU), O-(benzotriazol-1-yl)-di(dimethylamino)carbomony hexafluorophosphate (HBTU), O-(5-chlorobenzotriazol-1-yl)-di(dimethylamino)carbomony hexafluorophosphate (HCTU), O-(benzotriazol-1-yl)-di(dimethylamino)carbomony tetrafluoroborate (TBTU), and O-(N-succinimide)-di(dimethylamino)carbomony tetrafluorophosphate (TBTU). O-(N-endo-5-norcamphene-2,3-dicarbodiimide)-di(dimethylamino)carbodifluoroborate (TNTU), O-(7-azabenzotriazol-1-yl)-di(tetrahydropyrrolidinyl)carbodifluorophosphate (HAPyU), O-(benzotriazol-1-yl)-di(tetrahydropyrrolidinyl)carbodifluorophosphate (HBPyU), and benzotriazol-1-yloxy-tri(dimethylamino)phosphonium hexafluorophosphate (BOP).

[0015] The organophosphorus condensing agents are diphenylphosphine chloride (DPP-Cl), diethyl cyanophosphate (DECP), diphenyl azidophosphate (DPPA), thiodimethylphosphoazide (MPTA), and bis(2-oxo-3-azoloalkyl)phosphine chloride (BOP-Cl).

[0016] Specifically, the activator is selected from at least one of 4-N,N-dimethylpyridine, 4-pyrrolidinylpyridine, 1-hydroxybenzotriazole, 1-hydroxy-7-azabenzotriazole, and N-hydroxyphthalimide.

[0017] Specifically, the mass ratio of polyamide-imide copolymer to organic solvent is 10-20:100.

[0018] Specifically, the organic solvent is one or more of toluene, xylene, trimethylbenzene, and naphtha.

[0019] The present invention provides a method for preparing the above-mentioned polyamide-imide anti-wax agent, comprising the following steps: mixing the polyamide-imide copolymer and an organic solvent evenly to obtain the polyamide-imide anti-wax agent.

[0020] This invention provides the application of the above-mentioned polyamide-imide wax inhibitor in the removal and prevention of wax in petroleum and natural gas.

[0021] The present invention also provides a composite wax inhibitor, wherein modified flake graphite is added to the above-mentioned polyamide-imide wax inhibitor.

[0022] Specifically, the preparation method of the modified flake graphite is as follows: flake graphite powder is added to concentrated H2SO4 solution and stirred and impregnated at 40-60℃ for 1-2 hours. After impregnation, the powder is filtered, washed, and dried. Then, it is calcined at 800-1000℃ for 30-60 minutes to obtain a solid product. Subsequently, the solid product is immersed in hexadecyltrimethylammonium chloride solution and ultrasonically treated for 4-8 hours. After drying, the modified flake graphite is obtained.

[0023] Specifically, the mass fraction of the hexadecyltrimethylammonium chloride solution is 1-5%.

[0024] Specifically, the mass ratio of polyamide-imide wax inhibitor to modified flake graphite is 100-120:5-10.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) This invention uses monounsaturated fatty acids and maleic anhydride as raw materials to obtain a polyamide-imide wax inhibitor through copolymerization and graft modification. The polyamide-imide wax inhibitor has a long-chain fishbone structure with certain polar groups on the main chain and long alkyl chains of different lengths on both sides. The long alkyl chains on both sides are similar to the structure of paraffin wax and can co-crystallize with paraffin wax, inhibiting or weakening the precipitation of paraffin wax crystals. The polyamide-imide wax inhibitor prepared by this invention can form a spatial network structure in crude oil, which can further hinder the contact of paraffin wax molecules, inhibit the further crystallization and growth of paraffin wax, and prevent paraffin wax molecules from precipitating. The polyamide-imide wax inhibitor can be adsorbed on the surface of paraffin wax crystals, changing their wettability and dispersing the paraffin wax crystals in the crude oil.

[0027] (2) The composite anti-wax agent provided by the present invention also contains modified flake graphite. First, the flake graphite powder is treated with concentrated H2SO4 to introduce oxygen-containing functional groups into the graphite flakes. Then, the graphite is expanded by calcination, which increases the specific surface area and diffusivity of the flake graphite. Subsequently, it is immersed in a hexadecyltrimethylammonium chloride solution to load hexadecyltrimethylammonium chloride on the surface and between the flake graphite layers, thus obtaining modified flake graphite. Due to the introduction of modified flake graphite, the lubricity of crude oil is improved, the fluidity of crude oil is increased, and the pour point of crude oil is reduced, thereby reducing the deposition of wax on the pipe wall. The treatment of flake graphite with hexadecyltrimethylammonium chloride enhances the dispersibility and permeability of flake graphite in crude oil, increases the interfacial tension between paraffin and oil phase, and makes it difficult for wax to crystallize and precipitate by raising the nucleation barrier of wax, thus reducing the deposition of wax on the pipe wall.

[0028] (3) In the composite anti-wax agent provided by the present invention, the polyamide-imide copolymer improves the flow properties of crude oil by eutectic and / or adsorption with wax in crude oil; the modified flake graphite can improve the lubricity of crude oil, thereby improving the flowability of crude oil. The two work together to reduce the pour point of crude oil and reduce the deposition of wax on the pipe wall. Detailed Implementation

[0029] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0030] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0031] The flake graphite powder used in this invention was purchased from Wuhan Jiyesheng Chemical Co., Ltd., CAS No.: 7782-42-5.

[0032] Example 1

[0033] A method for preparing a polyamide-imide wax inhibitor includes the following steps:

[0034] 1 mol of cetearic acid and 1.1 mol of maleic anhydride were added to xylene and mixed thoroughly. Then, 0.0002 mol of tert-butyl peroxide was added, and the mixture was heated to 130 °C and reacted for 8 h. Then, 2 mol of tetratetramine, 2.1 mol of dicyclohexylcarbodiimide and 0.2 mol of 4-N,N-dimethylpyridine were added, and the mixture was reacted at 130 °C for 10 h. The solvent was removed to obtain a polyamide-imide copolymer.

[0035] Mix 15g of polyamide-imide copolymer and 100g of xylene evenly to obtain polyamide-imide wax inhibitor.

[0036] Example 2

[0037] A method for preparing a polyamide-imide wax inhibitor includes the following steps:

[0038] 1 mol of oleic acid and 1.5 mol of maleic anhydride were added to xylene and mixed thoroughly. Then, 0.0002 mol of diisopropyl peroxide dicarbonate was added, and the mixture was heated to 130 °C and reacted for 8 h. Then, 2.5 mol of octadecylamine, 2.1 mol of dicyclohexylcarbodiimide and 0.2 mol of 4-N,N-dimethylpyridine were added, and the mixture was reacted at 130 °C for 10 h. The solvent was removed to obtain a polyamide-imide copolymer.

[0039] Mix 10g of polyamide-imide copolymer and 100g of naphtha evenly to obtain polyamide-imide wax inhibitor.

[0040] Example 3

[0041] A method for preparing a polyamide-imide wax inhibitor includes the following steps:

[0042] 1 mol of myristoleic acid and 1.5 mol of maleic anhydride were added to xylene and mixed thoroughly. Then, 0.0002 mol of tert-butyl peroxide was added, and the mixture was heated to 120 °C and reacted for 10 h. Then, 2.5 mol of octadecylamine, 2.1 mol of dicyclohexylcarbodiimide and 0.2 mol of 4-N,N-dimethylpyridine were added, and the mixture was reacted at 120 °C for 10 h. The solvent was removed to obtain a polyamide-imide copolymer.

[0043] Mix 20g of polyamide-imide copolymer and 100g of toluene evenly to obtain polyamide-imide wax inhibitor.

[0044] Example 4

[0045] A method for preparing a composite anti-wax agent includes the following steps:

[0046] 1 mol of cetearic acid and 1.1 mol of maleic anhydride were added to xylene and mixed thoroughly. Then, 0.0002 mol of tert-butyl peroxide was added, and the mixture was heated to 130 °C and reacted for 8 h. Then, 2 mol of tetratetramine, 2.1 mol of dicyclohexylcarbodiimide and 0.2 mol of 4-N,N-dimethylpyridine were added, and the mixture was reacted at 130 °C for 10 h. The solvent was removed to obtain a polyamide-imide copolymer.

[0047] The modified flake graphite is prepared as follows: 10g of flake graphite powder is added to a concentrated H2SO4 solution and stirred and impregnated at 50℃ for 2h. After impregnation, the powder is filtered, washed, and dried. Then, it is calcined at 900℃ for 40min to obtain a solid product. Subsequently, the solid product is immersed in a 3wt% hexadecyltrimethylammonium chloride solution and ultrasonically treated for 5h. After drying, the modified flake graphite is obtained.

[0048] The composite wax inhibitor is obtained by mixing 15g of polyamide-imide copolymer, 8g of modified flake graphite and 100g of xylene evenly.

[0049] Example 5

[0050] A method for preparing a composite anti-wax agent includes the following steps:

[0051] 1 mol of oleic acid and 1.5 mol of maleic anhydride were added to xylene and mixed thoroughly. Then, 0.0002 mol of diisopropyl peroxide dicarbonate was added, and the mixture was heated to 130 °C and reacted for 8 h. Then, 2.5 mol of octadecylamine, 2.1 mol of dicyclohexylcarbodiimide and 0.2 mol of 4-N,N-dimethylpyridine were added, and the mixture was reacted at 130 °C for 10 h. The solvent was removed to obtain a polyamide-imide copolymer.

[0052] The modified flake graphite is prepared as follows: 10g of flake graphite powder is added to a concentrated H2SO4 solution and stirred and impregnated at 60℃ for 1h. After impregnation, the powder is filtered, washed, and dried. Then, it is calcined at 900℃ for 45min to obtain a solid product. Subsequently, the solid product is immersed in a 4wt% hexadecyltrimethylammonium chloride solution and ultrasonically treated for 6h. After drying, the modified flake graphite is obtained.

[0053] The composite wax inhibitor is obtained by mixing 10g of polyamide-imide copolymer, 5g of modified flake graphite and 100g of naphtha evenly.

[0054] The anti-wax properties of the anti-wax agents prepared in Examples 1-5 on crude oil were evaluated:

[0055] The evaluation of wax inhibitors shall be carried out in accordance with the provisions of standard SYT6300-2009 "Technical Conditions for Wax Inhibitors for Oil Production", and the specific steps are as follows:

[0056] Anhydrous crude oil samples were stirred and cooled in a stainless steel cup. During the cooling process, a temperature gradient existed between the oil sample and the inner wall of the stainless steel cup, resulting in paraffin deposition. The effectiveness of the paraffin inhibitor was evaluated by measuring the difference in the amount of paraffin deposited on the inner wall of the stainless steel cup under conditions of adding and not adding the inhibitor. The dosages of the paraffin inhibitor were 1000 ppm, 1500 ppm, and 2000 ppm, respectively. The test results are shown in Table 1.

[0057] Table 1

[0058]

[0059] The anti-wax properties of the anti-wax agents prepared in Examples 1-5 in natural gas condensate were evaluated:

[0060] Natural gas condensate samples were cooled to -18°C in a stainless steel cup and maintained for 2 hours. The flow state of the condensate was observed. The dosage of anti-wax agent added was 0 ppm, 1000 ppm, 1500 ppm and 2000 ppm, respectively. The test results are shown in Table 2.

[0061] Table 2

[0062] 0ppm 1000ppm 1500ppm 2000ppm Example 1 solidification Good liquidity Good liquidity Good liquidity Example 2 solidification Good liquidity Good liquidity Good liquidity Example 3 solidification Good liquidity Good liquidity Good liquidity Example 4 solidification Good liquidity Good liquidity Good liquidity Example 5 solidification Good liquidity Good liquidity Good liquidity Imported wax inhibitor solidification Good liquidity Good liquidity Good liquidity

[0063] Natural gas condensate samples were cooled to -40°C in a stainless steel cup and maintained for 2 hours. The flow state of the condensate was observed. The dosage of anti-wax agent added was 0 ppm, 1000 ppm, 2000 ppm and 3000 ppm, respectively. The test results are shown in Table 3.

[0064] Table 3

[0065] 0ppm 1000ppm 2000ppm 3000ppm Example 1 solidification solidification Good liquidity Good liquidity Example 2 solidification solidification solidification Good liquidity Example 3 solidification solidification Good liquidity Good liquidity Example 4 solidification Good liquidity Good liquidity Good liquidity Example 5 solidification Good liquidity Good liquidity Good liquidity Imported wax inhibitor solidification solidification solidification solidification

[0066] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A polyamide-imide paraffin inhibitor characterized in that, The polyamide-imide paraffin inhibitor is composed of a polyamide-imide copolymer and an organic solvent; The preparation method of the polyamide-imide copolymer comprises the following steps: adding a monounsaturated fatty acid and maleic anhydride into a solvent I, uniformly mixing, then adding an initiator, heating to 100-150 DEG C and reacting for 2-10 h, then adding an aliphatic primary amine, a condensing agent and an activator, reacting at 100-150 DEG C for 5-12 h, and removing the solvent I after the reaction to obtain the polyamide-imide copolymer. The molar ratio of the monounsaturated fatty acid, the maleic anhydride, the initiator, the aliphatic primary amine, the condensing agent and the activator is 1:1-2:0.0001-0.0005:2-3:1.5-2.5:0.1-0.

3.

2. The polyamide-imide paraffin inhibitor of claim 1, wherein, The monounsaturated fatty acid is selected from one or more of myristoleic acid, palmitoleic acid, oleic acid, ricinoleic acid and cetoleic acid; the solvent I is selected from one or more of toluene, xylene and trimethylbenzene; and the aliphatic primary amine is selected from one or more of octylamine, dodecylamine, hexadecylamine, eicosylamine and tetracosylamine.

3. The polyamide-imide paraffin inhibitor of claim 1, wherein, The initiator is selected from one or more of tert-butyl peroxybenzoate, azobis isobutyronitrile, benzoyl peroxide, cumene hydroperoxide and diisopropyl peroxydicarbonate; the condensing agent is selected from at least one of a carbodiimide condensing agent, an onium salt condensing agent and an organic phosphorus condensing agent; and the activator is selected from at least one of 4-N,N-dimethylpyridine, 4-pyrrolidinyl pyridine, 1-hydroxybenzotriazole, 1-hydroxy-7-azabenzotriazole and N-hydroxyphthalimide.

4. The polyamide-imide paraffin inhibitor of claim 1, wherein, The mass ratio of the polyamide-imide copolymer and the organic solvent is 10-20:100, and the organic solvent is one or more of toluene, xylene, trimethylbenzene and naphtha.

5. The process for the preparation of a polyamide-imide paraffin inhibitor according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: uniformly mixing the polyamide-imide copolymer and the organic solvent to obtain the polyamide-imide paraffin inhibitor.

6. The polyamide-imide paraffin inhibitor according to any one of claims 1-4 is used in oil and gas paraffin removal.

7. A composite wax inhibitor characterized in that, Modified flake graphite is added to the polyamide-imide paraffin inhibitor according to any one of claims 1-4.

8. The compound paraffin inhibitor of claim 7, wherein, The preparation method of the modified flake graphite is as follows: flake graphite powder is added into concentrated H2SO4 solution, stirred and immersed at 40-60 DEG C for 1-2 h, filtered, washed and dried after the immersion, then calcined at 800-1000 DEG C for 30-60 min to obtain a solid product, then the solid product is immersed in a cetyltrimethylammonium chloride solution, ultrasonically treated for 4-8 h, and dried to obtain the modified flake graphite.

9. The compound paraffin inhibitor of claim 7, wherein The mass ratio of the polyamide-imide paraffin inhibitor and the modified flake graphite is 100-120:5-10.

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