Phosphorus-free corrosion and scale inhibitor for oil field and preparation method of phosphorus-free corrosion and scale inhibitor

Abstract

The invention relates to the technical field of corrosion and scale inhibitors, and discloses a phosphorus-free corrosion and scale inhibitor for an oil field and a preparation method thereof.According to the phosphorus-free corrosion and scale inhibitor for the oil field, alkyl acyl chloride compounds such as tetraethylenepentamine, 1, 3, 5-benzene tricarboxylic acid diethyl ester and myristoyl chloride serve as reactants, and the phosphorus-free corrosion and scale inhibitor for the oil field is prepared. The scale inhibitor contains four carboxyl groups and more complexing sites, can generate strong chelation with calcium ions, inhibits the calcium ions from generating precipitates such as calcium sulfate and calcium carbonate, and shows very high scale inhibition rate and scale inhibition performance. And carboxyl and bis-imidazoline groups contained in the corrosion and scale inhibitor can form a coordination effect with the surface of a metal substrate such as a steel sheet, the corrosion and scale inhibitor is adsorbed on the surface of the metal substrate, and meanwhile, a hydrophobic protective film is formed on the surface of an alkyl long-chain substrate, so that the corrosion of the substrate is effectively inhibited, and the corrosion and scale inhibitor shows very high corrosion inhibition rate and corrosion resistance. The method has good practical application in the aspects of oilfield produced water treatment and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion and scale inhibitors, and specifically to a phosphorus-free corrosion and scale inhibitor for oil fields and a preparation method thereof. Background Art

[0002] At present, the main method of oil field development in China is water injection development, and the main source of the injected water is the associated water separated from the oil field produced fluid. However, the quality of the injected water is complex, with a high salinity, containing a large amount of inorganic salts, dissolved gases, bacteria and microorganisms, etc., which will cause corrosion of equipment such as wellbores and pipelines. At the same time, scaling phenomena such as calcium carbonate and calcium sulfate will occur in the oil well wellbores and injection formations. With the continuous exploitation of the oil field, the quality of the injected water is also deteriorating continuously, resulting in more and more serious corrosion and scaling, affecting the normal exploitation and production of the oil field. Usually, additives such as corrosion inhibitors and scale inhibitors need to be added to the oil field injection water.

[0003] Common corrosion inhibitors and scale inhibitors include alkyl imidazolines, Schiff bases, carboxylic acids, and phosphoric acids. Among them, phosphorus-based corrosion and scale inhibitors are inexpensive and easy to obtain, with a simple preparation method and good corrosion and scale inhibition effects, and have extensive practical applications in the oil field field. However, when phosphorus elements are discharged into the natural water environment, it will cause eutrophication of the water body, with greater harm. Therefore, it is necessary to develop phosphorus-free corrosion and scale inhibitors. The patent with the publication number CN114085188B discloses an imidazoline-type corrosion inhibitor and its preparation method and application. By reacting organic amines such as acrylonitrile, triethylenetetramine, and tetraethylenepentamine with organic acids such as lauric acid and myristic acid, an imidazoline-type corrosion inhibitor can be obtained, which can be applied to fields such as oil field oil production. However, this corrosion inhibitor does not show scale inhibition and anti-scaling performance. Summary of the Invention

[0004] The technical problem solved by the present invention: The present invention provides a phosphorus-free corrosion and scale inhibitor for oil fields with good corrosion inhibition performance and excellent scale inhibition performance.

[0005] The technical solution of the present invention: A preparation method of a phosphorus-free corrosion and scale inhibitor for oil fields:

[0006] (1) Add tetraethylenepentamine, diethyl 1,3,5-benzenetricarboxylate (CAS registration number: 4105-93-5), and xylene into a reaction vessel equipped with a condensing reflux tube and a water separator, reflux and remove water at 135 - 145 °C for 3 - 5 h, then raise the temperature to 200 - 210 °C, stir and react for 4 - 6 h, concentrate under reduced pressure, and separate by silica gel column chromatography, using petroleum ether and ethyl acetate as gradient elution solvents to obtain intermediate A. The reaction formula is:

[0007]

[0008] (2) In an ice bath, add dichloromethane, intermediate A, alkyl acyl chloride compound, and triethylamine to the reaction vessel, stir and react at 15 - 25 °C for 12 - 18 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain intermediate B. The reaction formula is:

[0009]

[0010] (3) Add ethanol, intermediate B, and aqueous potassium hydroxide solution to the reaction vessel equipped with a condenser reflux tube, stir and react at 80 - 90 °C for 8 - 10 h, add concentrated hydrochloric acid dropwise to adjust the pH to 4 - 5, a large amount of precipitate will form, filter by suction, and dry to obtain a phosphorus-free corrosion and scale inhibitor for oil fields. The reaction formula is:

[0011]

[0012] Preferably, in (1), the molar ratio of tetraethylenepentamine to diethyl 1,3,5-benzenetricarboxylate is 1:(1.75 - 1.85).

[0013] Preferably, in (2), the molar ratio of intermediate A, alkyl acyl chloride compound, and triethylamine is 1:(1 - 1.2):(1 - 1.3). The molecular formula of the alkyl acyl chloride compound is C n H 2n+1 COCl, where n is any integer from 13 to 17.

[0014] Preferably, in (3), the mass concentration of the aqueous potassium hydroxide solution is (130 - 160) g / L.

[0015] The beneficial technical effects of the present invention: The present invention uses tetraethylenepentamine, diethyl 1,3,5-benzenetricarboxylate, and alkyl acyl chloride compounds such as myristoyl chloride as reactants to prepare a phosphorus-free corrosion and scale inhibitor for oil fields. It contains four carboxyl hydrophilic groups and imidazoline groups, making the corrosion and scale inhibitor have good water solubility.

[0016] The corrosion and scale inhibitor prepared by the present invention contains four carboxyl groups, has more complexing sites, can strongly chelate with calcium ions, inhibit the formation of precipitates such as calcium sulfate and calcium carbonate by calcium ions, and thus exhibits a high scale inhibition rate and scale inhibition performance. And the carboxyl groups and bis-imidazoline groups contained can form a coordination effect with the surface of metal substrates such as steel sheets, adsorb the corrosion and scale inhibitor on the surface of the metal substrate, and at the same time form a hydrophobic protective film on the surface of the alkyl long-chain substrate, inhibiting the contact of corrosive media such as acids with the surface of the metal substrate, effectively inhibiting the corrosion of the substrate, and showing a high corrosion inhibition rate and anti-corrosion performance. It has good practical applications in aspects such as oil field produced water treatment. Specific embodiments

[0017] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0018] Example 1:

[0019] (1) Add 40 mmol of tetraethylenepentamine, 72 mmol of diethyl 1,3,5-benzenetricarboxylate, and 12 mL of xylene to a reaction vessel equipped with a condenser reflux tube and a water separator. Reflux and remove water at 140 °C for 3 h, then raise the temperature to 210 °C, stir and react for 4 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain intermediate A. The structural formula is The actual yield is 14.72 g.

[0020] (2) In an ice bath, add 300 mL of dichloromethane, 50 mmol of intermediate A, 54 mmol of myristoyl chloride, and 65 mmol of triethylamine to the reaction vessel. Stir and react at 15 °C for 18 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain intermediate B. The structural formula is The actual yield is 35.84 g.

[0021] (3) Add 200 mL of ethanol, 20 g of intermediate B, and 200 mL of a potassium hydroxide aqueous solution with a concentration of 160 g / L to a reaction vessel equipped with a condenser reflux tube. Stir and react at 80 °C for 8 h, add concentrated hydrochloric acid dropwise to adjust the pH to 4, a large amount of precipitate will precipitate, filter by suction, and dry to obtain a phosphorus-free corrosion and scale inhibitor for oil fields. The structural formula is The actual yield is 14.80 g.

[0022] Example 2:

[0023] (1) Add 40 mmol of tetraethylenepentamine, 70 mmol of diethyl 1,3,5-benzenetricarboxylate, and 12 mL of xylene to a reaction vessel equipped with a condenser reflux tube and a water separator. Reflux and remove water at 145 °C for 3 h, then raise the temperature to 200 °C, stir and react for 6 h, concentrate under reduced pressure, and separate by silica gel column chromatography to obtain intermediate A. The actual yield is 13.89 g.

[0024] (2) In an ice bath, add 400 mL of dichloromethane, 50 mmol of intermediate A, 50 mmol of palmitoyl chloride, and 50 mmol of triethylamine to the reaction vessel. Stir and react at 25 °C for 12 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain intermediate B. The structural formula is The actual yield is 36.89 g.

[0025] (3) Add 250 mL of ethanol, 20 g of intermediate B, and 250 mL of an aqueous potassium hydroxide solution with a concentration of 130 g / L to the reaction vessel equipped with a condenser reflux tube. Stir and react at 90 °C for 8 h, add concentrated hydrochloric acid dropwise to adjust the pH to 5, a large amount of precipitate will form, filter by suction, and dry to obtain a phosphorus-free corrosion and scale inhibitor for oil fields. The structural formula is The actual yield is 14.21 g.

[0026] Example 3:

[0027] (1) Add 40 mmol of tetraethylenepentamine, 74 mmol of diethyl 1,3,5-benzenetricarboxylate, and 15 mL of xylene to the reaction vessel equipped with a condenser reflux tube and a water separator. Reflux and remove water at 135 °C for 5 h, then raise the temperature to 210 °C, stir and react for 4 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain intermediate A. The actual yield is 16.25 g.

[0028] (2) In an ice bath, add 400 mL of dichloromethane, 50 mmol of intermediate A, 60 mmol of stearoyl chloride, and 65 mmol of triethylamine to the reaction vessel. Stir and react at 20 °C for 18 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain intermediate B. The structural formula is The actual yield is 37.22 g.

[0029] (3) Add 250 mL of ethanol, 20 g of intermediate B, and 250 mL of an aqueous potassium hydroxide solution with a concentration of 150 g / L to the reaction vessel equipped with a condenser reflux tube. Stir and react at 85 °C for 10 h, add concentrated hydrochloric acid dropwise to adjust the pH to 4, a large amount of precipitate will form, filter by suction, and dry to obtain a phosphorus-free corrosion and scale inhibitor for oil fields. The structural formula is The actual yield is 13.95 g.

[0030] In Comparative Example 1, intermediate A (prepared in the same way as in Example 1) was used as the corrosion and scale inhibitor.

[0031] In Comparative Example 2, intermediate B (prepared in the same way as in Example 1) was used as the corrosion and scale inhibitor.

[0032] Comparative Example 3:

[0033] (1) Add 40 mmol of tetraethylenepentamine, 72 mmol of ethyl 4-carboxybenzoate (structural formula is CAS Registry Number 713-57-5), and 12 mL of xylene into a reaction vessel equipped with a condenser reflux tube and a water separator. Reflux with water removal at 140 °C for 3 h, then raise the temperature to 210 °C, stir and react for 4 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain Intermediate 1.

[0034] (2) In an ice bath, add 300 mL of dichloromethane, 50 mmol of Intermediate 1, 54 mmol of myristoyl chloride, and 65 mmol of triethylamine into the reaction vessel. Stir and react at 15 °C for 18 h, concentrate under reduced pressure, and separate by silica gel column chromatography using petroleum ether and ethyl acetate as gradient elution solvents to obtain Intermediate 2.

[0035] (3) Add 200 mL of ethanol, 20 g of Intermediate 2, and 200 mL of a potassium hydroxide aqueous solution with a concentration of 160 g / L into a reaction vessel equipped with a condenser reflux tube. Stir and react at 80 °C for 8 h, add concentrated hydrochloric acid dropwise to adjust the pH to 4, a large amount of precipitate will form, filter by suction, and dry to obtain a phosphorus-free corrosion and scale inhibitor for oil fields, with the structural formula

[0036] Weigh 50 mg of the corrosion and scale inhibitor and add 500 mL of distilled water into a graduated cylinder, stir for 30 min, and observe the solubility.

[0037] The test results are shown in Table 1.

[0038] Table 1 Water Solubility Test of Corrosion and Scale Inhibitor

[0039]

[0040] After testing, the corrosion and scale inhibitors prepared in Examples 1-3 contain four carboxyl hydrophilic groups and imidazoline groups, making the corrosion and scale inhibitors have good water solubility and enabling better practical applications of the corrosion and scale inhibitors in aspects such as oil field produced water treatment.

[0041] The corrosion and scale inhibitors of Comparative Example 1 and Comparative Example 2 do not contain carboxyl groups and have very poor water solubility. The corrosion and scale inhibitor of Comparative Example 3 contains two hydrophilic carboxyl groups and imidazoline groups and also has good water solubility.

[0042] Test the scale inhibition performance of the corrosion and scale inhibitor on oil field produced water (from Huabei Oilfield) according to the method of SY / T 5673-2020. The test temperature is 60 °C, and the dosage of the corrosion and scale inhibitor is 20 mg / L.

[0043] Test the corrosion inhibition performance of the corrosion and scale inhibitor on steel sheets according to the method of SY / T 5273-2014. The dosage of the corrosion and scale inhibitor is 40 mg / L.

[0044] The test results are shown in Table 2.

[0045] Table 2 Performance Test of Corrosion and Scale Inhibitor

[0046] Scale inhibition rate (%) Corrosion inhibition rate (%) Example 1 68.6 71.4 Example 2 68.1 73.8 Example 3 67.5 73.0 Comparative Example 1 19.7 40.4 Comparative Example 2 13.0 55.9 Comparative Example 3 47.2 64.3

[0047] After testing, the corrosion and scale inhibitors prepared in Examples 1-3 have higher scale inhibition rates and corrosion inhibition rates. The main reason is that the corrosion and scale inhibitor contains four carboxyl groups, has more complexing sites, can have a strong chelating effect with calcium ions, inhibits the formation of precipitates such as calcium sulfate and calcium carbonate by calcium ions, and shows a very high scale inhibition rate and scale inhibition performance. And the carboxyl groups and bis-imidazoline groups contained can form a coordination effect with the surface of metal substrates such as steel sheets, adsorb the corrosion and scale inhibitor on the surface of the metal substrate, and form a hydrophobic protective film on the surface of the alkyl long-chain substrate, inhibiting the contact of corrosive media such as acids with the surface of the metal substrate and inhibiting the corrosion of the substrate, showing a very high corrosion inhibition rate and anti-corrosion performance.

[0048] In Comparative Example 1, intermediate A was used as the corrosion and scale inhibitor. It does not contain carboxyl groups, has a very weak chelating effect with calcium ions, resulting in a very low scale inhibition rate and poor scale inhibition performance. And it does not contain a hydrophobic alkyl long chain, resulting in a lower corrosion inhibition rate and poor anti-corrosion performance. Intermediate B in Comparative Example 2 does not contain carboxyl groups, resulting in lower scale inhibition and corrosion inhibition rates.

[0049] The corrosion and scale inhibitor prepared in Comparative Example 3 only contains two carboxyl groups, has a weak chelating effect with calcium ions, and the coordination effect with the surface of the metal substrate is lower than that of the corrosion and scale inhibitor in Example 1, resulting in the scale inhibition rate and corrosion inhibition rate being lower than those in Example 1.

[0050] Taking the corrosion and scale inhibitor prepared in Example 2 as an example, the dosage was controlled at 20-60 mg / L. The scale inhibition performance on oilfield produced water was tested. The test results are shown in Table 3.

[0051] Table 3 Scale Inhibition Performance Test of Corrosion and Scale Inhibitors with Different Dosages

[0052] Dosage (mg / L) Scale inhibition rate (%) 20 68.1 30 80.4 40 89.6 50 96.3 60 95.9

[0053] Taking the corrosion and scale inhibitor prepared in Example 2 as an example, the dosage was controlled at 40-70 mg / L. The corrosion inhibition performance on steel sheets was tested. The test results are shown in Table 4.

[0054] Table 4 Corrosion Inhibition Performance Test of Corrosion and Scale Inhibitors with Different Dosages

[0055] Dosage (mg / L) Corrosion inhibition rate (%) 40 73.8 50 88.9 60 95.0 70 99.2

[0056] It can be seen from Tables 3-4 that the corrosion and scale inhibitors with different dosages all show good scale inhibition rates and corrosion inhibition rates. The highest rates reach 96.3% and 99.2% respectively.

[0057] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A phosphorus-free corrosion and scale inhibitor for oil fields, characterized in that: The structural formula of the phosphorus-free corrosion and scale inhibitor for oil fields is: n is any integer between 13 and 17.

2. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 1, characterized in that: The preparation method is: (1) adding tetraethylenepentamine, diethyl 1,3,5-benzenetricarboxylate, and xylene to a reaction vessel equipped with a condenser reflux tube and a water separator, reacting, concentrating under reduced pressure, and separating by silica gel column chromatography to obtain intermediate A; (2) In an ice bath, add dichloromethane, intermediate A, alkyl acyl chloride compound, and triethylamine to a reaction vessel, stir to react, concentrate under reduced pressure, and separate by silica gel column chromatography to obtain intermediate B; (3) Add ethanol, intermediate B, and potassium hydroxide aqueous solution into a reaction vessel equipped with a condensation reflux tube to react, add concentrated hydrochloric acid dropwise to adjust the pH, precipitate, filter, and dry to obtain a phosphorus-free corrosion and scale inhibitor for oil fields.

3. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 2, characterized in that: In the above (1), the molar ratio of tetraethylenepentamine to diethyl 1,3,5-benzenetricarboxylate is 1:(1.75-1.85).

4. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 2, characterized in that: In the above (1), the reaction is first refluxed with water at 135-145°C for 3-5 hours, then the temperature is raised to 200-210°C and the reaction is carried out for 4-6 hours.

5. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 2, characterized in that: In the above (2), the molar ratio of intermediate A, alkyl acyl chloride compound and triethylamine is 1:(1-1.2):(1-1.3).

6. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 5, characterized in that: The molecular formula of the alkyl acyl chloride compound is C n H 2n+1 COCl, n is any integer from 13 to 17.

7. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 2, characterized in that: In the step (2), the reaction temperature is 15-25°C and the reaction time is 12-18h.

8. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 2, characterized in that: In (3), the mass concentration of the potassium hydroxide aqueous solution is (130-160) g / L.

9. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 2, characterized in that: In the step (3), the reaction temperature is 80-90°C and the reaction time is 8-10h.

10. The method for preparing the phosphorus-free corrosion and scale inhibitor for oil fields according to claim 2, characterized in that: In the above (3), the pH is adjusted to 4-5.

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