Preparation method and application of a pour point and viscosity reducer for waxy crude oil

Abstract

The present invention provides a preparation method and application of a pour point and viscosity reducing agent for waxy crude oil, and relates to the technical field of petrochemical industry. The crude oil pour point and viscosity reducing agent in the present invention is a ternary polymer synthesized from acrylic acid, olefinic acid and amide. The preparation method of the polymer is to mix acrylic acid, olefinic acid, amide and solvent in a certain proportion, and when the temperature rises to the reaction temperature under the protection of nitrogen, drip an initiator, and stop the reaction after a certain reaction time to obtain the polymer. The present invention is characterized in that the preparation process of the polymer is simple, easy to mass produce, and can obtain a higher pour point and viscosity reducing effect in crude oil with a wax content of 3 to 25%, and significantly improve the low-temperature fluidity of waxy crude oil.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical engineering, and in particular to a preparation method and application of a waxy crude oil pour point and viscosity reducer. Background Art

[0002] About 80% of the world's energy needs come from oil, natural gas and coal. Oil accounts for about 35% to 50% of the energy supply and is one of the most important energy sources in contemporary times. Crude oil is characterized by high wax content, high freezing point and high viscosity, and the wax content can be as high as 15% to 37%.

[0003] The paraffin deposition problem in the oil production process is a key issue that makes production efficiency and production operation costs difficult to control. When crude oil is extracted from underground reservoirs under high temperature and pressure, it is usually transported over long distances through pipelines. However, the physical and chemical properties of crude oil will change fundamentally during transportation, causing many problems. Because in a low temperature environment, wax crystals in crude oil will nucleate and precipitate, and then gradually adhere to the pipe wall to cause wax deposition. Once a large amount of wax is deposited on the pipe wall, the pressure drop of the pipeline will increase, and higher pressure is required to transport crude oil. Paraffin deposition can also cause equipment failure, blockage of upstream and downstream transportation pipelines, reduced flow, and loss of production, transportation, and storage capacity. Over time, paraffin deposition will continue to increase, so that a large number of oil wells are shut down, countless pipelines are blocked, transport ships are out of service, and refineries are shut down at specific times. All of these consequences caused by paraffin deposition will cause huge economic losses.

[0004] As time goes by, the study of wax deposition has received considerable attention from researchers. The problem of wax deposition was raised in 1923, and from the 1970s to the present, people's understanding of the physical properties of wax and the entire wax deposition process has gradually deepened, and the wax prevention and control measures proposed and implemented, that is, prevention and repair technologies, have also gradually increased. At present, researchers have explored some methods to solve the transportation problem of waxy crude oil, such as mechanical removal, heating, insulation pipelines, dilution and emulsification. However, these methods require high energy and cost, and it is difficult to restart after stopping transportation. Adding a low dose of copolymer pour point depressant (PPD) is considered to be the most effective solution.

[0005] In the process of decreasing the temperature of pipeline transportation, polymer pour point depressants can improve the morphology, size and aggregation state of wax crystals precipitated from waxy crude oil at low temperature, inhibit the tendency of wax crystals to form a spatial network structure, and weaken the strength of wax crystals to form a spatial network structure, that is, change the microscopic rheological structure of waxy crude oil at low temperature through certain specific physical and chemical interactions with the components related to waxy crude oil. From a macroscopic point of view, polymer pour point depressants can reduce the pour point, viscosity and yield stress of waxy crude oil to below WAT, weaken its complex rheological responses such as viscoelasticity and thixotropy, that is, improve the macroscopic rheological properties of crude oil. Therefore, after adding a low dose of PPD to waxy crude oil, the rheological properties will be significantly improved, and the pour point depressant has the advantages of adapting to harsh environments, simple operation, and low equipment investment, and has been widely used. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation method and application of a waxy crude oil pour point and viscosity reducer. The pour point and viscosity reducer provided by the present invention can give full play to the effect of the pour point and viscosity reducer in inhibiting wax deposition, significantly reduce the pour point and viscosity of the waxy crude oil, and improve the fluidity of the waxy crude oil in a pipeline, so as to solve the problem of transporting the waxy crude oil under low temperature conditions.

[0007] To achieve the above purpose, the solution adopted by the present invention is:

[0008] The terpolymer is synthesized from three different monomer units of acrylic acid ester, olefinic acid and amide, and the terpolymer is used as a waxy crude oil pour point and viscosity reducer. The preparation method of the polymer is to mix acrylic acid ester, olefinic acid, amide and solvent in a certain proportion, and when the temperature rises to the reaction temperature under the protection of nitrogen, an initiator is added dropwise, and the reaction is stopped after a certain reaction time.

[0009] The acrylic acid ester structure is as follows (1):

[0010]

[0011] n=any one of 0 to 21, where n is an odd number.

[0012] The structural formula of olefinic acid is as follows (2):

[0013]

[0014] n1=any one of 4,5,6,8,10;

[0015] n2=any one of 7, 8, 9, 11, 12, 13.

[0016] The amide structural formula is as follows (3):

[0017]

[0018] Formula (3)

[0019] R=H, -CH3, -CH2CH3, any one of.

[0020] The monomer ratio of the polymerization reaction is 2-6:1-3:1-4.

[0021] The solvent for the polymerization reaction is an alcohol ether solvent, including diethylene glycol monomethyl ether, propylene glycol methyl ether, dipropylene glycol dimethyl ether, diethylene glycol monobutyl ether and cyclohexanediol monomethyl ether.

[0022] The initiator is an azo compound initiator, including azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate or azoisobutylcyanamide.

[0023] The reaction temperature of the polymerization reaction is 60-80° C., and the reaction time is 1-8 hours.

[0024] The terpolymer can achieve higher pour point and viscosity reduction effects in crude oil with a wax content of 3-25%.

[0025] The advantages and beneficial effects of the present invention over the prior art are as follows:

[0026] The present invention provides a ternary polymer as a pour point and viscosity reducer for waxy crude oil. Experimental results show that the provided crude oil pour point and viscosity reducer can achieve the best pour point and viscosity reduction effect when the concentration is 200-2000ppm and the temperature is 50-90℃, the pour point reduction range is 10-45℃, and the viscosity reduction rate is 30-90%. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention is described below in conjunction with the preparation method of the terpolymer and its application. Some embodiments of the present invention are given herein, but the present invention is not limited to the embodiments described herein.

[0028] Example 1

[0029] Methyl methacrylate, 13-docosahexaenoic acid and N-methyl-2-acrylamide were mixed in a molar ratio of 2:1:1, diethylene glycol monobutyl ether was used as solvent, and under the protection of nitrogen, the reaction temperature was raised to 60°C, and azobisisobutyronitrile initiator was added, and the reaction was carried out at a constant temperature for 1 hour to obtain a ternary polymer.

[0030] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 5% at a dosage of 200 ppm and a temperature of 50° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was 0° C., the pour point reduction amplitude was 11.5° C., and the viscosity reduction rate was 35%.

[0031] Example 2

[0032] Behenyl acrylate, 10-heptadecenoic acid and acrylamide were mixed in a molar ratio of 3:2:3, and cyclohexanediol monomethyl ether was used as solvent. Under the protection of nitrogen, the reaction temperature was raised to 70°C, and azobisisobutyronitrile initiator was added. The reaction was carried out at a constant temperature for 4 hours to obtain a ternary polymer.

[0033] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 5% at a dosage of 800 ppm and a temperature of 70° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil". The pour point of the oil added with the pour point and viscosity reducer was -2° C., the pour point reduction amplitude was 13.5° C., and the viscosity reduction rate was 38%.

[0034] Example 3

[0035] Dodecyl methacrylate, 9-octadecenoic acid and crotonamide were mixed in a molar ratio of 6:3:1, and diethylene glycol monomethyl ether was used as solvent. Under the protection of nitrogen, the reaction temperature was raised to 80°C, and azobisisoheptanenitrile initiator was added. The reaction was kept at a constant temperature for 8 hours to obtain a ternary polymer.

[0036] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 12% at a dosage of 1200ppm and a temperature of 90°C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was -3.5°C, the pour point reduction amplitude was 20.5°C, and the viscosity reduction rate was 48%.

[0037] Example 4

[0038] Methyl methacrylate, 9-octadecenoic acid and N-methyl-2-acrylamide were mixed in a molar ratio of 3:2:1, and dipropylene glycol dimethyl ether was used as solvent. Under the protection of nitrogen, the reaction temperature was raised to 60°C, and azobisisoheptanenitrile initiator was added. The reaction was kept at a constant temperature for 4 hours to obtain a ternary polymer.

[0039] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 12% at a dosage of 1600 ppm and an addition temperature of 60° C. The pour point of the oil product was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil product with the pour point and viscosity reducer added was 0° C., the pour point reduction amplitude was 17° C., and the viscosity reduction rate was 43%.

[0040] Example 5

[0041] Dodecyl methacrylate, 13-docosahexaenoic acid and acrylamide were mixed in a molar ratio of 2:1:4, and propylene glycol methyl ether was used as solvent. When the reaction temperature was raised to 70°C under the protection of nitrogen, dimethyl azobisisobutyrate initiator was added, and the reaction was carried out at a constant temperature for 8 hours to obtain a ternary polymer.

[0042] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 21% at a dosage of 1000 ppm and an addition temperature of 80°C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was -2.5°C, the pour point reduction amplitude was 26°C, and the viscosity reduction rate was 61%.

[0043] Example 6

[0044] Behenyl acrylate, 10-heptadecenoic acid and crotonamide were mixed in a molar ratio of 6:1:4, and diethylene glycol monomethyl ether was used as solvent. When the reaction temperature was raised to 60°C under the protection of nitrogen, dimethyl azobisisobutyrate initiator was added, and the reaction was carried out at a constant temperature for 4 hours to obtain a ternary polymer.

[0045] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 12% at a dosage of 1200 ppm and a temperature of 70° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was -10.5° C., the pour point reduction amplitude was 27.5° C., and the viscosity reduction rate was 63%.

[0046] Example 7

[0047] Methyl methacrylate, 9-octadecenoic acid and crotonamide were mixed in a molar ratio of 3:2:3, diethylene glycol monobutyl ether was used as solvent, and when the reaction temperature reached 70°C under the protection of nitrogen, azoisobutylcyanamide initiator was added, and the reaction was carried out at a constant temperature for 8 hours to obtain a ternary polymer.

[0048] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 21% at a dosage of 2000 ppm and a temperature of 90° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was -17° C., the pour point reduction amplitude was 40.5° C., and the viscosity reduction rate was 83%.

[0049] Example 8

[0050] Dodecyl methacrylate, 10-heptadecenic acid and N-methyl-2-acrylamide were mixed in a molar ratio of 2:1:1, diethylene glycol monobutyl ether was used as solvent, and when the reaction temperature reached 70°C under the protection of nitrogen, azoisobutylcyanamide initiator was added, and the reaction was carried out at a constant temperature for 2 hours to obtain a ternary polymer.

[0051] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 5% at a dosage of 400 ppm and an addition temperature of 60° C. The pour point of the oil product was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil product with the pour point and viscosity reducer added was 1.5° C., the pour point reduction amplitude was 10° C., and the viscosity reduction rate was 30%.

[0052] Example 9

[0053] Behenyl acrylate, 13-eicosenoic acid and N-methyl-2-acrylamide were mixed in a molar ratio of 6:1:2, and diethylene glycol monobutyl ether was used as solvent. When the reaction temperature reached 60°C under the protection of nitrogen, azobisisobutyronitrile initiator was added and the reaction was carried out at a constant temperature for 8 hours to obtain a ternary polymer.

[0054] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 12% at a dosage of 600 ppm and a temperature of 70° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was -2° C., the pour point reduction amplitude was 19° C., and the viscosity reduction rate was 47%.

[0055] Example 10

[0056] Methyl methacrylate, 10-heptadecenic acid and acrylamide were mixed in a molar ratio of 3:2:1, diethylene glycol monobutyl ether was used as solvent, and when the reaction temperature reached 80°C under the protection of nitrogen, azobisisoheptanenitrile initiator was added, and the reaction was carried out at a constant temperature for 5 hours to obtain a ternary polymer.

[0057] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 21% at a dosage of 800 ppm and a temperature of 80° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was -9.5° C., the pour point reduction amplitude was 33° C., and the viscosity reduction rate was 75%.

[0058] Comparative Example 1

[0059] Methyl methacrylate, 9-octadecenoic acid and N-methyl-2-acrylamide were mixed in a molar ratio of 1:1:1, diethylene glycol monomethyl ether was used as solvent, and under the protection of nitrogen, the reaction temperature was raised to 65°C, and azobisisobutyronitrile initiator was added, and the reaction was carried out at a constant temperature for 4 hours to obtain a ternary polymer.

[0060] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 5% at a dosage of 500 ppm and a temperature of 50° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil added with the pour point and viscosity reducer was 10° C., the pour point reduction amplitude was 1.5° C., and the viscosity reduction rate was 10%.

[0061] Comparative Example 2

[0062] Behenyl methacrylate, 13-eicosenoic acid and N-hydroxymethyl acrylamide were mixed in a molar ratio of 6:1:4, diethylene glycol monomethyl ether was used as solvent, and under the protection of nitrogen, the reaction temperature was raised to 80°C, and azobisisoheptonitrile initiator was added, and the reaction was carried out at a constant temperature for 2 hours to obtain a ternary polymer.

[0063] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 5% at a dosage of 400 ppm and an addition temperature of 80° C. The pour point of the oil product was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil product with the pour point and viscosity reducer added was 8.5° C., the pour point reduction amplitude was 3° C., and the viscosity reduction rate was 12%.

[0064] Comparative Example 3

[0065] Behenyl acrylate, 10-heptadecenoic acid and methacrylamide were mixed in a molar ratio of 2:1:3, and propylene glycol methyl ether was used as solvent. When the reaction temperature was raised to 60°C under the protection of nitrogen, dimethyl azobisisobutyrate initiator was added, and the reaction was carried out at a constant temperature for 8 hours to obtain a ternary polymer.

[0066] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 12% at a dosage of 700 ppm and an addition temperature of 60° C. The pour point of the oil product was measured according to "SY / T 0541-2009 Determination of pour point of crude oil", and the pour point of the oil product with the pour point and viscosity reducer added was 10° C., the pour point reduction amplitude was 7° C., and the viscosity reduction rate was 19%.

[0067] Comparative Example 4

[0068] Methyl methacrylate, 13-docosahexaenoic acid and N-isopropylacrylamide were mixed in a molar ratio of 3:1:2, and dipropylene glycol dimethyl ether was used as solvent. Under the protection of nitrogen, the reaction temperature was raised to 70°C, and azoisobutylcyanamide initiator was added. The reaction was carried out at a constant temperature for 10 hours to obtain a ternary polymer.

[0069] The crude oil pour point and viscosity reducer prepared above was added to crude oil with a wax content of 21% at a dosage of 800 ppm and a temperature of 80° C. The pour point of the oil was measured according to "SY / T 0541-2009 Determination of pour point of crude oil". The pour point of the oil with the pour point and viscosity reducer added was 14.5° C., the pour point reduction amplitude was 9° C., and the viscosity reduction rate was 23%.

[0070] Compared with the embodiments, the changes in the monomer types and monomer ratios in the comparative examples will change the number of effective functional groups in the polymerization product, resulting in poor freezing and viscosity reduction effects of the polymerization product, while the differences in other reaction conditions will affect the molecular weight and dispersion of the polymerization product, and will also affect the performance of the polymerization product.

Claims

1. A method for preparing a pour point and viscosity reducer for waxy crude oil, characterized in that: The waxy crude oil pour point and viscosity reducer is a ternary polymer composed of acrylic acid, olefinic acid and amide. The preparation method of the polymer is to mix acrylic acid, olefinic acid, amide and solvent, and when the temperature rises to the reaction temperature under the protection of nitrogen, add an initiator dropwise, and stop the reaction after a certain reaction time. When the concentration of crude oil pour point and viscosity reducer is 200-2000ppm and the temperature is 50-90℃, the pour point reduction range is 10-45℃ and the viscosity reduction rate is 30-90%; The molar ratio of the acrylic acid ester, the olefinic acid and the amide is 2-6:1-3:1-4; The acrylic acid ester is methyl methacrylate, behenyl acrylate or dodecyl methacrylate; The olefinic acid structural formula is as follows (2): n1=any one of 4,5,6,8,10; n2=any one of 7,8,9,11,12,13; The amide structural formula is as follows (3): R1 or R2=H, -CH3, -CH2CH3.

2. The method for preparing the pour point and viscosity reducer for waxy crude oil according to claim 1, characterized in that: The solvent for the polymerization reaction is an alcohol ether solvent, including diethylene glycol monomethyl ether, propylene glycol methyl ether, dipropylene glycol dimethyl ether, diethylene glycol monobutyl ether or cyclohexanediol monomethyl ether.

3. The method for preparing the pour point and viscosity reducer for waxy crude oil according to claim 1, characterized in that: The initiator is an azo compound initiator, including azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate or azoisobutylcyanamide.

4. The method for preparing the pour point and viscosity reducer for waxy crude oil according to claim 1, characterized in that: The reaction temperature of the polymerization reaction is 60-80° C., and the reaction time is 1-8 hours.

5. The pour point and viscosity reducing agent prepared by the preparation method according to any one of claims 1 to 4 is used to reduce the pour point and viscosity of waxy crude oil.

6. The use according to claim 5, characterized in that: The terpolymer has a relatively high pour point and viscosity reduction effect in crude oil with a wax content of 3 to 25%.

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