Wax crystal dispersion inhibitor as well as preparation method and application thereof

Abstract

The invention discloses a wax crystal dispersion inhibitor and a preparation method and application thereof.A copolymer is obtained through copolymerization and side group modification, a side chain of the prepared copolymer has a long alkyl chain similar to a paraffin molecule, and the long alkyl chain can form eutectic with the paraffin molecule or adsorb a paraffin crystal; the microcrystalline wax is dispersed in crude oil, crystal aggregation and growth are inhibited, hydrophilic groups connected to a main chain can be exposed on the surfaces of paraffin crystals, crystallization of the paraffin crystals is further inhibited, and a good paraffin inhibition effect is achieved. In the wax crystal dispersion inhibitor provided by the invention, the copolymer is subjected to eutectic and / or adsorption with wax in crude oil, so that the flowing property of the crude oil is improved; the modified crystalline flake graphite can improve the lubricity of crude oil, so that the fluidity of the crude oil is improved, the copolymer and the modified crystalline flake graphite act together, the condensation point of the crude oil is reduced, and deposition of wax on a pipe wall is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of wax inhibitor preparation, and in particular to a wax crystal dispersion inhibitor and a preparation method and application thereof. Background Art

[0002] Most of the crude oil produced in my country is paraffin-based crude oil, with high wax content and relatively high wax precipitation point as its main characteristics. For example, the wax content of crude oil from Daqing, Changqing, North China, Zhongyuan and other oil fields is greater than 10%, among which the wax content of individual blocks of Daqing and Changqing crude oil is as high as over 30%, and the wax precipitation point is as high as 29°C. As a result, during the crude oil production and gathering and transportation process, when the wellbore and pipeline temperature is lower than the wax precipitation point, the wax in the crude oil begins to crystallize and precipitate and deposit on the oil casing and gathering and transportation pipelines, bringing serious negative impact on the production and operation of the oil field.

[0003] At present, the wax removal and prevention technologies commonly used in oil fields mainly include mechanical wax removal technology, thermal wax removal technology, surface energy wax prevention technology, magnetic wax prevention technology, microbial wax removal and prevention technology, chemical wax removal and prevention technology, etc. Chemical wax prevention technology has many advantages such as quick effect, simple operation, and low cost, so it is widely used in many oil fields. Most polymer wax inhibitors are oil-soluble comb polymers with side chains. After being injected into the well and mixed with crude oil, the structure similar to paraffin in its molecules forms a eutectic with the wax molecules. The polar groups in its molecules cause the formed crystal nuclei to distort and deform, preventing the wax crystals from growing further. In addition, the long molecular chains of the polymer can form a network structure throughout the crude oil, disperse small crystal nuclei, prevent them from aggregating and depositing, and easily flow away with the oil flow. However, the current polymer wax inhibitors have the disadvantages of poor wax prevention effect, especially poor low-temperature effect. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a wax crystal dispersion inhibitor and a preparation method and application thereof. The prepared wax crystal dispersion inhibitor has good anti-wax performance, especially low-temperature anti-wax performance.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for preparing a wax crystal dispersion inhibitor comprises the following steps:

[0007] S1. Preparation of copolymer: Add glycidyl ether and maleic anhydride containing double bonds to solvent I, add initiator after mixing evenly, heat to 100-150° C. and react for 2-10 hours, then add aliphatic primary amine or fatty alcohol, mix evenly and react at 100-150° C. for 4-12 hours, remove solvent I after the reaction is completed, and obtain copolymer;

[0008] S2. Preparation of modified flake graphite: adding flake graphite powder to a concentrated H2SO4 solution, stirring and impregnating at 40-60°C for 1-2h, filtering, washing, and drying after impregnation, and then calcining at 800-1000°C for 30-60min to obtain a solid product, then immersing the solid product in a hexadecyltrimethylammonium chloride solution, ultrasonically treating for 4-8h, and drying to obtain modified flake graphite;

[0009] S3, uniformly mixing the copolymer, modified flake graphite and organic solvent to obtain a wax crystal dispersion inhibitor.

[0010] Specifically, in step S1, the molar ratio of the glycidyl ether containing a double bond, maleic anhydride, initiator, aliphatic primary amine or aliphatic alcohol is 1:1-1.5:0.0001-0.0005:1-3.

[0011] Specifically, in step S1, the glycidyl ether containing a double bond is selected from one or more of allyl alcohol glycidyl ether, methacrylate glycidyl ether, acrylate glycidyl ether, and 4-hydroxybutyl acrylate glycidyl ether.

[0012] Specifically, in step S1, the initiator is selected from one or more of azobisisobutyl cyanide, benzoyl peroxide, isopropylbenzene hydroperoxide, tert-butyl perbenzoate, and diisopropyl peroxydicarbonate.

[0013] Specifically, in step S1, the aliphatic primary amine is selected from one or more of octylamine, dodecylamine, octadecylamine and tetracosylamine.

[0014] Specifically, in step S1, the fatty alcohol is selected from one or more of n-octanol, dodecanol, hexadecanol, and hexacosanol.

[0015] Specifically, in step S1, the solvent I is selected from one or more of toluene, xylene, trimethylbenzene, and naphtha.

[0016] Specifically, in step S3, the mass ratio of the copolymer, the modified flake graphite and the organic solvent is 10-25:5-10:100.

[0017] Specifically, in step S3, the organic solvent is selected from one or more of toluene, xylene, trimethylbenzene, and naphtha.

[0018] The present invention provides a wax crystal dispersion inhibitor prepared by the above preparation method.

[0019] The present invention also provides application of the wax crystal dispersion inhibitor in the removal and prevention of wax in petroleum and natural gas.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention obtains a copolymer through copolymerization and side group modification. The side chain of the prepared copolymer has a long alkyl chain similar to that of a paraffin molecule. The long alkyl chain can form a eutectic with the paraffin molecule or adsorb paraffin crystals, so that microcrystalline paraffin is dispersed in crude oil, inhibiting crystal aggregation and growth. The hydrophilic groups connected to the main chain can be exposed on the surface of the paraffin crystals, further inhibiting the crystallization of the paraffin crystals, thereby achieving a good anti-wax effect.

[0022] (2) The present invention first uses concentrated H2SO4 to treat flake graphite powder to introduce oxygen-containing functional groups into the graphite flakes, then expands the graphite by roasting, thereby increasing the specific surface area and diffusivity of the flake graphite, and then immerses the flake graphite in a hexadecyltrimethylammonium chloride solution to load hexadecyltrimethylammonium chloride on the surface and interlayers of the flake graphite to obtain modified flake graphite. Due to the introduction of the modified flake graphite, the lubricity of crude oil is improved, the fluidity of crude oil is increased, and the freezing point of crude oil is lowered, thereby reducing the deposition of wax on the wall of the oil pipe; the flake graphite is treated with hexadecyltrimethylammonium chloride to enhance the dispersibility and permeability of the flake graphite in crude oil, increase the interfacial tension between paraffin wax and the oil phase, and make it difficult for the wax to crystallize and precipitate by increasing the nucleation barrier of the wax, thereby reducing the deposition of wax on the pipe wall.

[0023] (3) In the wax crystal dispersion inhibitor provided by the present invention, the copolymer improves the flowability of the crude oil by forming a eutectic and / or adsorbing with the wax in the crude oil; the modified flake graphite can improve the lubricity of the crude oil, thereby increasing the flowability of the crude oil. The composite wax inhibitor provided by the present invention has the characteristics of both a wax crystal modifier and a surfactant-type wax inhibitor. The copolymer and the modified flake graphite work together to lower the freezing point of the crude oil and reduce the deposition of wax on the pipe wall. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0025] It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention were purchased through commercial channels.

[0026] The flake graphite powder used in the present invention was purchased from Wuhan Jiyesheng Chemical Co., Ltd., CAS No.: 7782-42-5.

[0027] Example 1

[0028] A method for preparing a wax crystal dispersion inhibitor comprises the following steps:

[0029] S1. Preparation of copolymer: 1 mol of allyl alcohol glycidyl ether and 1.1 mol of maleic anhydride are added to xylene, mixed evenly, and then 0.0001 mol of tert-butyl peroxybenzoate is added, and the temperature is raised to 135° C. to react for 4 hours, and then 2 mol of tetracosylamine is added thereto, mixed evenly, and the reaction is continued at 135° C. for 8 hours. After the reaction is completed, the solvent is removed to obtain a copolymer;

[0030] S2. Preparation of modified flake graphite: 10 g of flake graphite powder was added to a concentrated H2SO4 solution, stirred and impregnated at 60°C for 1 h, filtered, washed and dried after impregnation, and then calcined at 900°C for 45 min to obtain a solid product, which was then immersed in a 4 wt% hexadecyltrimethylammonium chloride solution, ultrasonically treated for 6 h, and dried to obtain modified flake graphite;

[0031] S3. Evenly mix 15 g of the copolymer, 8 g of the modified flake graphite and 100 g of an organic solvent, wherein the organic solvent consists of 20% xylene, 40% trimethylbenzene and 40% naphtha, to obtain a wax crystal dispersion inhibitor.

[0032] Example 2

[0033] A method for preparing a wax crystal dispersion inhibitor comprises the following steps:

[0034] S1. Preparation of copolymer: 1 mol of glycidyl methacrylate and 1.2 mol of maleic anhydride are added to xylene, mixed evenly, and then 0.0002 mol of azobisisobutyl cyanide is added, and the temperature is raised to 135° C. to react for 4 hours, and then 3 mol of hexacosanol is added thereto, mixed evenly, and the reaction is continued at 135° C. for 8 hours. After the reaction is completed, the solvent is removed to obtain a copolymer;

[0035] S2. Preparation of modified flake graphite: 10 g of flake graphite powder was added to a concentrated H2SO4 solution, stirred and impregnated at 60°C for 1 h, filtered, washed and dried after impregnation, and then calcined at 900°C for 30 min to obtain a solid product, which was then immersed in a 3 wt% hexadecyltrimethylammonium chloride solution, ultrasonically treated for 4 h, and dried to obtain modified flake graphite;

[0036] S3. Evenly mix 12 g of the copolymer, 6 g of the modified flake graphite and 100 g of an organic solvent, wherein the organic solvent consists of 20% xylene, 40% trimethylbenzene and 40% naphtha, to obtain a wax crystal dispersion inhibitor.

[0037] Example 3

[0038] A method for preparing a wax crystal dispersion inhibitor comprises the following steps:

[0039] S1. Preparation of copolymer: 1 mol of glycidyl acrylate and 1.3 mol of maleic anhydride are added to xylene, mixed evenly, and then 0.0002 mol of azobisisobutyl cyanide is added, and the temperature is raised to 135° C. to react for 4 hours, and then 2 mol of hexadecanol is added thereto, mixed evenly, and the reaction is continued at 135° C. for 8 hours. After the reaction is completed, the solvent is removed to obtain a copolymer;

[0040] S2. Preparation of modified flake graphite: 10 g of flake graphite powder was added to a concentrated H2SO4 solution, stirred and impregnated at 60°C for 1 h, filtered, washed and dried after impregnation, and then calcined at 900°C for 45 min to obtain a solid product, which was then immersed in a 4 wt% hexadecyltrimethylammonium chloride solution, ultrasonically treated for 6 h, and dried to obtain modified flake graphite;

[0041] S3. Evenly mix 10 g of the copolymer, 10 g of the modified flake graphite and 100 g of an organic solvent, wherein the organic solvent consists of 20% toluene, 20% xylene, 30% trimethylolbenzene and 30% naphtha, to obtain a wax crystal dispersion inhibitor.

[0042] Example 4

[0043] A method for preparing a wax crystal dispersion inhibitor comprises the following steps:

[0044] S1. Preparation of copolymer: 1 mol of 4-hydroxybutyl acrylate glycidyl ether and 1.1 mol of maleic anhydride were added to xylene, mixed evenly, and then 0.0003 mol of benzoyl peroxide was added, and the temperature was raised to 120° C. for reaction for 6 h, and then 2 mol of octadecylamine was added thereto, mixed evenly, and the reaction was continued at 120° C. for 10 h. After the reaction was completed, the solvent was removed to obtain a copolymer;

[0045] S2. Preparation of modified flake graphite: 10 g of flake graphite powder was added to a concentrated H2SO4 solution, stirred and impregnated at 60°C for 1 h, filtered, washed and dried after impregnation, and then calcined at 1000°C for 30 min to obtain a solid product, which was then immersed in a 3 wt% hexadecyltrimethylammonium chloride solution, ultrasonically treated for 8 h, and dried to obtain modified flake graphite;

[0046] S3. Evenly mix 20 g of the copolymer, 5 g of the modified flake graphite and 100 g of an organic solvent, wherein the organic solvent consists of 20% xylene, 40% trimethylbenzene and 40% naphtha, to obtain a wax crystal dispersion inhibitor.

[0047] Comparative Example 1

[0048] A method for preparing a wax crystal dispersion inhibitor comprises the following steps:

[0049] S1. Preparation of copolymer: 1 mol of allyl alcohol glycidyl ether and 1.1 mol of maleic anhydride are added to xylene, mixed evenly, and then 0.0001 mol of tert-butyl peroxybenzoate is added, and the temperature is raised to 135° C. to react for 4 hours, and then 2 mol of tetracosylamine is added thereto, mixed evenly, and the reaction is continued at 135° C. for 8 hours. After the reaction is completed, the solvent is removed to obtain a copolymer;

[0050] S2. Evenly mix 15 g of the copolymer and 100 g of an organic solvent, wherein the organic solvent consists of 20% xylene, 40% trimethylbenzene and 40% naphtha, to obtain a wax crystal dispersion inhibitor.

[0051] Comparative Example 2

[0052] A method for preparing a wax crystal dispersion inhibitor comprises the following steps:

[0053] S1. Preparation of copolymer: 1 mol of allyl alcohol glycidyl ether and 1.1 mol of maleic anhydride are added to xylene, mixed evenly, and then 0.0001 mol of tert-butyl peroxybenzoate is added, and the temperature is raised to 135° C. to react for 4 hours, and then 2 mol of tetracosylamine is added thereto, mixed evenly, and the reaction is continued at 135° C. for 8 hours. After the reaction is completed, the solvent is removed to obtain a copolymer;

[0054] S2. Evenly mix 15 g of copolymer, 8 g of flake graphite and 100 g of an organic solvent, wherein the organic solvent consists of 20% of xylene, 40% of trimethylol and 40% of naphtha, to obtain a wax crystal dispersion inhibitor.

[0055] The wax crystal dispersion inhibitors prepared in Examples 1-4 and Comparative Examples 1-2 were evaluated for their anti-wax performance in crude oil:

[0056] The evaluation is carried out in accordance with the provisions of the standard SYT6300-2009 "Technical Conditions for Oil Production Cleaners and Wax Inhibitors", and the specific steps are as follows:

[0057] The water-free crude oil sample was stirred and cooled in a stainless steel cup. During the cooling process of the oil sample, a temperature gradient existed between the oil sample and the inner wall of the stainless steel cup, which resulted in paraffin deposition. The effect of the paraffin inhibitor was evaluated by measuring the difference in the amount of paraffin deposited on the inner wall of the stainless steel with and without the addition of the agent. The addition amount of the wax crystal dispersion inhibitor was 1000ppm, 1500ppm and 2000ppm respectively. The test results are shown in Table 1:

[0058] Table 1

[0059]

[0060] The anti-wax performance of the wax crystal dispersion inhibitors prepared in Examples 1-4 and Comparative Examples 1-2 in natural gas condensate was evaluated:

[0061] The natural gas condensate sample was cooled to -40°C in a stainless steel cup and kept for 2 hours to observe the flow state of the condensate. The addition amount of wax crystal dispersion inhibitor was 0ppm, 1000ppm, 2000ppm and 3000ppm respectively. The test results are shown in Table 2:

[0062] Table 2

[0063] 0ppm 1000ppm 2000ppm 3000ppm 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 Comparative Example 1 solidification solidification Good liquidity Good liquidity Comparative Example 2 solidification Good liquidity Good liquidity Good liquidity

[0064] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to the scope of protection claimed in the present invention.

Claims

1. A method for preparing a wax crystal dispersion inhibitor, characterized in that: The steps include: S1. Preparation of copolymer: Add glycidyl ether and maleic anhydride containing double bonds to solvent I, add initiator after mixing evenly, heat to 100-150° C. and react for 2-10 hours, then add aliphatic primary amine or fatty alcohol, mix evenly and react at 100-150° C. for 4-12 hours, remove solvent I after the reaction is completed, and obtain copolymer; S2. Preparation of modified flake graphite: adding flake graphite powder to a concentrated H2SO4 solution, stirring and impregnating at 40-60°C for 1-2h, filtering, washing, and drying after impregnation, and then calcining at 800-1000°C for 30-60min to obtain a solid product, then immersing the solid product in a hexadecyltrimethylammonium chloride solution, ultrasonically treating for 4-8h, and drying to obtain modified flake graphite; S3, uniformly mixing the copolymer, modified flake graphite and organic solvent to obtain a wax crystal dispersion inhibitor.

2. The method for preparing the wax crystal dispersion inhibitor according to claim 1, characterized in that: In step S1, the molar ratio of the glycidyl ether containing a double bond, maleic anhydride, initiator, aliphatic primary amine or aliphatic alcohol is 1:1-1.5:0.0001-0.0005:1-3.

3. The method for preparing the wax crystal dispersion inhibitor according to claim 1, characterized in that: In step S1, the glycidyl ether containing a double bond is selected from one or more of allyl alcohol glycidyl ether, methacrylate glycidyl ether, acrylate glycidyl ether, and 4-hydroxybutyl acrylate glycidyl ether.

4. The method for preparing the wax crystal dispersion inhibitor according to claim 1, characterized in that: In step S1, the initiator is selected from one or more of azobisisobutyl cyanide, benzoyl peroxide, isopropylbenzene hydroperoxide, tert-butyl perbenzoate, and diisopropyl peroxydicarbonate.

5. The method for preparing the wax crystal dispersion inhibitor according to claim 1, characterized in that: In step S1, the aliphatic primary amine is selected from one or more of octylamine, dodecylamine, octadecylamine, and tetracosylamine; and the fatty alcohol is selected from one or more of n-octanol, dodecyl alcohol, hexadecanol, and hexacosyl alcohol.

6. The method for preparing the wax crystal dispersion inhibitor according to claim 1, characterized in that: In step S1, the solvent I is selected from one or more of toluene, xylene, trimethylbenzene, and naphtha.

7. The method for preparing the wax crystal dispersion inhibitor according to claim 1, characterized in that: In step S3, the mass ratio of the copolymer, the modified flake graphite and the organic solvent is 10-25:5-10:

100.

8. The method for preparing the wax crystal dispersion inhibitor according to claim 1, characterized in that: In step S3, the organic solvent is selected from one or more of toluene, xylene, trimethylbenzene, and naphtha.

9. The wax crystal dispersion inhibitor prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the wax crystal dispersion inhibitor as claimed in claim 9 in the removal and prevention of wax in petroleum and natural gas.

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