Corrosion inhibitor capable of resisting H2S and CO2 corrosion at high temperature and preparation method of corrosion inhibitor

Abstract

The invention discloses a corrosion inhibitor capable of resisting H2S and CO2 corrosion at high temperature and a preparation method thereof, and belongs to the technical field of synthesis of corrosion inhibitors, and the corrosion inhibitor is finally obtained by dissolving a triazine derivative in an organic solvent, adding a halide for reaction, firstly performing vacuum concentration after the reaction is finished, then adding an anti-solvent for precipitation, performing suction filtration and washing. According to the corrosion inhibitor capable of resisting H2S and CO2 corrosion at the high temperature and the preparation method of the corrosion inhibitor, a triazine ring, a benzene ring, a naphthalene ring, hydroxyl, sulfydryl, cyano, amino and the like are introduced into corrosion inhibitor molecules, the binding energy of the molecules and metal Fe atoms is increased, binding is firmer, the corrosion inhibitor is of a quaternary ammonium salt structure, and the corrosion inhibitor can be used for resisting H2S and CO2 corrosion at the high temperature. Due to the excellent water solubility, the corrosion inhibitor can form a homogeneous mixture with water to be in full contact with the surface of steel, so that the corrosion inhibition rate is higher than 90% under the working conditions that the temperature is higher than 90 DEG C, the degree of mineralization is higher than 18000 mg / L and CO2 and H2S are rich, and the corrosion inhibitor has a good anti-corrosion effect on carbon steel and is small in dosage and free of pollution to the environment.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion inhibitor synthesis, and in particular to a corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature and a preparation method thereof.

[0002] The prior application to which this invention claims priority is application number 202410235115.2, with filing date March 1, 2024. Background Art

[0003] In the exploration and development of oil and gas, the water content and temperature inside oil and gas wells are getting higher and higher in the middle and late stages of exploitation. The corrosion problem of carbon steel pipelines is becoming increasingly prominent. Existing steel materials cannot meet the requirements of corrosion protection under high temperature and high pressure. In addition, the corrosion of steel can cause production accidents in oil and gas fields, resulting in economic losses. Therefore, corrosion and protection work in oil and gas fields is extremely important.

[0004] At present, corrosion inhibitors mainly adsorb on the metal surface through the electron-rich groups on their molecules to form a continuous or discontinuous adsorption layer and a protective film layer, blocking the cathode, anode or both the cathode and cathode reactions of the corrosion process, thereby producing a corrosion inhibition effect.

[0005] There are many studies on room temperature CO2 corrosion inhibitors, including imidazoline, Schiff base, organic amine, quaternary ammonium salt, natural extract and other corrosion inhibitors. The above corrosion inhibitors can effectively prevent corrosion at room temperature. When the temperature is higher than 80℃, the corrosion inhibition rate drops sharply and cannot meet industrial applications.

[0006] CN114685372A discloses an oil-soluble high-efficiency imidazoline corrosion inhibitor with multiple adsorption sites and a preparation method thereof. The molecular structure of the oxazoline corrosion inhibitor involved has three imidazoline rings, which effectively improves the adsorption capacity of the corrosion inhibitor to the metal matrix. The introduction of three 17-carbon straight-chain olefins further improves the corrosion inhibition capacity of the corrosion inhibitor by improving the hydrophobicity of the corrosion inhibitor, and can meet the corrosion inhibition requirements of high-temperature wells (120°C) and high-mineralization CO2 gas drive wells. However, it still does not meet the temperature of deep working conditions in oil and gas fields (above 180°C), and is not suitable for working conditions containing hydrogen sulfide gas. Summary of the invention

[0007] The purpose of the present invention is to provide a corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature and a preparation method thereof. Triazine rings, benzene rings, naphthalene rings, hydroxyl groups, mercapto groups, cyano groups and amino groups are introduced into the corrosion inhibitor molecules, which increases the binding energy between the molecules and metal Fe atoms, making the binding stronger. The corrosion inhibitor can be firmly adsorbed on the metal surface, so that the corrosion inhibition rate is higher than 90% under working conditions with a temperature higher than 90°C, a mineralization higher than 18000 mg / L, and rich in CO2 and H2S.

[0008] To achieve the above object, the present invention provides a corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature, and the structural formula of the corrosion inhibitor is as follows:

[0009]

[0010] Wherein X is Cl, Br or I;

[0011] R is thiol, alcohol, amine or cyano.

[0012] Preferably, the thiols are

[0013] Preferably, the alcohol is

[0014] Preferably, the cyano group is

[0015] The present invention also provides a method for preparing a corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature, comprising the following steps: dissolving a triazine derivative in an organic solvent, adding a halide to react, first reducing pressure and concentrating after the reaction is completed, then adding an anti-solvent to precipitate, filtering and washing to obtain a corrosion inhibitor. The specific reaction equation is as follows:

[0016]

[0017] Preferably, the triazine derivative is obtained by reacting trichlorotriazine and dimethylamine, and the synthesis method is as follows: add trichlorotriazine to a three-necked beaker, add dioxane as a solvent, stir at room temperature until dissolved, then add dimethylamine, stir at room temperature for 0.5-2h, then add KOH, stir at 40°C for 1-3h, then heat to 84°C and stir for 6-12h, cool the reaction system to room temperature, add the reaction solution to a large amount of ice water to precipitate solids, filter and dry to obtain the triazine derivative.

[0018] Preferably, the organic solvent is one or two of toluene, chloroform, ethanol, isopropanol, acetone, acetonitrile, tetrahydrofuran, N,N-dimethylformamide, the anti-solvent is one or two of diethyl ether and ethyl acetate, and the reaction temperature when the halide is added is 40-100°C.

[0019] The invention discloses an application of a corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature in carbon steel corrosion protection.

[0020] Therefore, the present invention adopts the above-mentioned corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature and its preparation method, uses the corresponding halide to introduce electronegative functional groups such as triazine ring, benzene ring, naphthalene ring, hydroxyl, thiol, cyano and amino groups into the corrosion inhibitor molecule through a one-step quaternization reaction, which not only increases the binding energy between the molecule and the metal Fe atom, making the binding more firm, so that the corrosion inhibitor can be firmly adsorbed on the metal surface, but also the quaternary ammonium salt structure greatly increases the water solubility of the corrosion inhibitor, so that the corrosion inhibitor is uniformly adsorbed on the steel surface, thereby achieving a corrosion inhibition rate of more than 90% under working conditions of a temperature of 90-160°C, a mineralization of 18000-200000 mg / L, and rich in CO2 and H2S.

[0021] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0022] The present invention provides a corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature, and the structural formula of the corrosion inhibitor is as follows:

[0023]

[0024] Wherein X is Cl, Br or I;

[0025] R is thiol, alcohol, amine or cyano, wherein:

[0026] Thiols are

[0027] Alcohols are

[0028] Cyano groups are

[0029] The preparation method of the above-mentioned corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature is as follows:

[0030]

[0031] (1) Preparation of triazine derivatives:

[0032] The triazine derivative is obtained by the reaction of trichlorotriazine and dimethylamine. The synthesis method is as follows: add trichlorotriazine to a three-necked beaker, add dioxane as a solvent, and stir at room temperature until dissolved. Then add dimethylamine and stir at room temperature for 1 hour. Then add KOH and stir at 40°C for 2 hours. Then heat to 84°C and stir for 10 hours. Cool the reaction system to room temperature, add the reaction solution to a large amount of ice water to precipitate solids, filter and dry to obtain the triazine derivative.

[0033] (2) The triazine derivative is dissolved in an organic solvent;

[0034] In the present invention, the preferred organic solvent is one or two of toluene, chloroform, ethanol, isopropanol, acetone, acetonitrile, tetrahydrofuran, and N,N-dimethylformamide. In this reaction, the organic solvent dissolves the triazine derivative to ensure the stability of the subsequent reaction.

[0035] (3) Adding a halide to the triazine derivative solution for reaction. Different halides require different reaction temperatures. The reaction temperature when adding the halide is 40-100°C.

[0036] In the present invention, the reaction temperature is limited to ensure the yield of the main reaction and reduce the generation of by-products. Low reaction temperature leads to the inability to proceed with the reaction or low yield of the product, and high reaction temperature leads to the occurrence of side reactions.

[0037] (4) After the reaction is completed, the mixture is concentrated under reduced pressure, and then an anti-solvent is added for precipitation. The anti-solvent is preferably one or both of ether and ethyl acetate. The final product is precipitated in the anti-solvent. The anti-solvent is miscible with the original solvent but cannot dissolve the target product, i.e., the quaternary ammonium salt corrosion inhibitor. As the anti-solvent diffuses into the original solvent, the quaternary ammonium salt corrosion inhibitor is gradually precipitated from the original solvent. The precipitate is filtered and washed to obtain the corrosion inhibitor.

[0038] The present invention also provides the application of the above-mentioned corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature in oil and gas field pipelines for corrosion prevention. Specifically, the application environment temperature is 90-160°C and the mineralization degree is 18000-200000 mg / L.

[0039] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1

[0041] A mercaptan corrosion inhibitor that resists H2S and CO2 corrosion at high temperatures. When R is 3-chloro-1-propanethiol, the reaction formula is as follows:

[0042]

[0043] The specific preparation method is: take 10mmol of triazine derivative, dissolve it in a mixed solvent of 50mL acetone and 50mL chloroform, then add 60mmol of 3-chloro-1-propanethiol, react at 40℃ for 8h, after the reaction is completed, first concentrate under reduced pressure, then add it to a mixed solvent of 75mL ether and 75mL ethyl acetate for precipitation, filter and wash to obtain a high temperature resistant thiol corrosion inhibitor.

[0044] Embodiment 2

[0045] An alcohol corrosion inhibitor that resists H2S and CO2 corrosion at high temperature. When R is p-hydroxybenzyl chloride, the reaction formula is as follows:

[0046]

[0047] The specific preparation method is as follows: take 10 mmol of a triazine derivative and dissolve it in a mixed solvent of 60 mL of isopropanol and 40 mL of acetone, then add 70 mmol of p-hydroxybenzyl chloride, reflux for 8 hours, and after the reaction is completed, first concentrate under reduced pressure, then add it to 150 mL of ether for precipitation, filter and wash to obtain a high-temperature resistant alcohol corrosion inhibitor.

[0048] Embodiment 3

[0049] An amine corrosion inhibitor that resists H2S and CO2 corrosion at high temperatures. When R is p-aminobenzyl chloride, the reaction formula is as follows:

[0050]

[0051] The specific preparation method is as follows: take 10 mmol of a triazine derivative and dissolve it in a mixed solvent of 30 mL of ethanol and 70 mL of tetrahydrofuran, then add 70 mmol of p-aminobenzyl chloride, react at 40°C for 10 hours, and after the reaction is completed, first concentrate under reduced pressure, then add it to 120 mL of ethyl acetate for precipitation, filter and wash to obtain a high temperature resistant amine corrosion inhibitor.

[0052] Embodiment 4

[0053] A cyano corrosion inhibitor that resists H2S and CO2 corrosion at high temperatures. When R is p-cyanobenzyl chloride, the reaction formula is as follows:

[0054]

[0055] The specific preparation method is: take 10mmol of triazine derivative and dissolve it in 100mL of toluene, then add 90mmol of p-cyanobenzyl chloride, react at 100℃ for 6h, after the reaction is completed, first reduce the pressure and concentrate, then add it to 150mL of ether to precipitate, filter and wash to obtain the high temperature resistant cyanide corrosion inhibitor.

[0056] Comparative Example 1

[0057] A mercaptan corrosion inhibitor that resists H2S and CO2 corrosion at high temperatures. When R is 3-chloro-1-propanethiol, the reaction formula is as follows:

[0058]

[0059] The specific preparation method is: take 10mmol of triazine derivative, dissolve it in a mixed solvent of 50mL acetone and 50mL chloroform, then add 60mmol of 3-chloro-1-propanethiol, react at 25℃ for 8h, after the reaction is completed, first concentrate under reduced pressure, then add it to a mixed solvent of 75mL ether and 75mL ethyl acetate for precipitation, filter and wash to obtain a high temperature resistant thiol corrosion inhibitor.

[0060] Comparative Example 2

[0061] A cyano corrosion inhibitor that resists H2S and CO2 corrosion at high temperatures. When R is p-cyanobenzyl chloride, the reaction formula is as follows:

[0062]

[0063] The specific preparation method is: take 10mmol of triazine derivative and dissolve it in 100mL of toluene, then add 90mmol of p-cyanobenzyl chloride, react at 25℃ for 6h, after the reaction is completed, first reduce the pressure and concentrate, then add it to 150mL of ether for precipitation, filter and wash, and obtain a high temperature resistant cyanide corrosion inhibitor.

[0064] Experimental Testing

[0065] Take 6 groups of oil and gas field pipelines of the same batch and the same model, and respectively coat them with the corrosion inhibitors obtained in Example 1, Example 2, Example 3, Example 4, Comparative Example 1, and Comparative Example 2. The coating process and dosage are consistent and comply with the SYT7408-2018 Technical Specifications for Corrosion Inhibitor Coating and Continuous Filling of Oil and Gas Gathering and Transportation Pipelines, and then operate under the same working conditions.

[0066] The specific working conditions are as follows: When the total mineralization of the corrosive medium is 25764.8 mg / L, K + and Na + 8245.4mg / L, Ca 2+ 1873.3mg / L, Mg 2+ 347.8mg / L, Cl - 16329.8mg / L, SO4 2- 63.5mg / L, HCO3 - It is 482.4 mg / L, the rotation speed of Q235 steel sheet is 10 rpm, the corrosion cycle is 3 days, the total pressure is 8MPa, of which the partial pressures of CO2, H2S and N2 are 2MPa, 2MPa and 4MPa respectively.

[0067] When the dosage of each corrosion inhibitor was 400 mg / L, the corrosion rate at different temperatures was evaluated and the corrosion inhibition rate was calculated. The results are shown in Table 1.

[0068] Table 1 Corrosion inhibition performance of high temperature resistant corrosion inhibitors at different temperatures

[0069]

[0070] It can be seen from the above table that, compared with Example 1, although the only difference between Example 1 and Comparative Example 1 is the temperature, the final effect achieved is also different. The reason is that the reaction temperature greatly affects the conversion rate of the reaction. Compared with 25°C, the reaction temperature of 40°C can accelerate the reaction rate, improve the conversion rate, and help to form the desired product structure. Example 4 and Comparative Example 2 are the same as above; and the high temperature corrosion inhibitor prepared by the present invention has a corrosion inhibition rate of up to 89.61-91.89% at 150°C, indicating that the prepared corrosion inhibitor has good performance at high temperatures.

[0071] Therefore, the present invention adopts the above-mentioned corrosion inhibitor that resists H2S and CO2 corrosion at high temperature and its preparation method. Triazine ring, benzene ring, naphthalene ring, hydroxyl, mercapto, cyano and amino groups are introduced into the corrosion inhibitor molecule, which increases the binding energy between the molecule and the metal Fe atom, making the binding stronger. The corrosion inhibitor can be firmly adsorbed on the metal surface, and this type of corrosion inhibitor is a quaternary ammonium salt structure. The excellent water solubility enables the corrosion inhibitor to form a homogeneous mixture with water and fully contact with the steel surface, thereby achieving a corrosion inhibition rate of more than 90% under working conditions with a temperature higher than 90°C, a mineralization higher than 18000 mg / L, and rich in CO2 and H2S. It has a good anti-corrosion effect on carbon steel, and is used in a small amount and is pollution-free to the environment.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature, characterized in that: The structural formula of the corrosion inhibitor is as follows: Wherein X is Cl, Br or I; R is thiol, alcohol, amine or cyano.

2. The corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature according to claim 1, characterized in that: Thiols are 3. The corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature according to claim 1, characterized in that: Alcohols are 4. The high temperature corrosion inhibitor for resisting H2S and CO2 corrosion according to claim 1, characterized in that: The amines are 5. The corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature according to claim 1, characterized in that: Cyano groups are 6. A method for preparing a corrosion inhibitor for resisting H2S and CO2 corrosion at high temperature as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: After the triazine derivative is dissolved in an organic solvent, a halide is added to react. After the reaction is completed, it is first concentrated under reduced pressure, and then an anti-solvent is added to precipitate. The corrosion inhibitor is filtered and washed to obtain the corrosion inhibitor. The specific reaction equation is as follows:

7. The method for preparing a corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature according to claim 6, characterized in that: The triazine derivative is obtained by the reaction of trichlorotriazine and dimethylamine. The synthesis method is as follows: add trichlorotriazine to a three-necked beaker, add dioxane as a solvent, stir at room temperature until dissolved, then add dimethylamine, stir at room temperature for 0.5-2h, then add KOH, stir at 40°C for 1-3h, then heat to 84°C and stir for 6-12h, cool the reaction system to room temperature, add the reaction solution to a large amount of ice water to precipitate solids, filter and dry to obtain the triazine derivative.

8. The method for preparing a corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature according to claim 6, characterized in that: The organic solvent is one or two of toluene, chloroform, ethanol, isopropanol, acetone, acetonitrile, tetrahydrofuran, and N,N-dimethylformamide; the anti-solvent is one or two of diethyl ether and ethyl acetate; and the reaction temperature when the halide is added is 40-100°C.

9. Use of a corrosion inhibitor resistant to H2S and CO2 corrosion at high temperature as described in any one of claims 1 to 5 in carbon steel corrosion protection.

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