Corrosion inhibitor for inhibiting corrosion of carbon dioxide and hydrogen sulfide coexisting system oil well pipe

Abstract

The invention discloses a corrosion inhibitor for inhibiting corrosion of a carbon dioxide and hydrogen sulfide coexisting system oil well pipe, and relates to the technical field of corrosion inhibitors, the corrosion inhibitor comprises the following raw materials by weight: 1-10 parts of a compound A, 1-10 parts of a compound B, 1-5 parts of a surfactant, 0.5-1.5 parts of a bactericide, 1-5 parts of a deoxidant and 80-100 parts of a solvent; a preparation method of the compound A comprises the following steps: sequentially carrying out dehydration reaction and cyclization reaction on tung oil, triethylene tetramine and xylene in a reaction container, then adding thiourea, and reacting at 125-165 DEG C for 8-12 hours to obtain the compound A; a preparation method of the compound B comprises the following steps: sequentially carrying out dehydration reaction and cyclization reaction on oleic acid, diethylenetriamine and xylene in a reaction container, adding benzyl chloride, and reacting at 85-95 DEG C for 3-5 hours to obtain the compound B. The corrosion inhibitor disclosed by the invention has an excellent corrosion inhibition effect.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion inhibitors, in particular to a corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist. Background Art

[0002] With the increasing depth of oil and gas field exploration and production, the downhole environment is becoming increasingly complex. Especially in high-temperature, high-pressure reservoirs with the coexistence of sour gases, corrosion has become a key factor restricting the long-term service safety of oil well tubing. In production environments containing the coexistence of carbon dioxide (CO2) and hydrogen sulfide (H2S), the interaction between these two acidic media not only accelerates the corrosion rate of carbon steel tubing but can also form complex corrosion product films, further leading to serious consequences such as localized corrosion, seriously threatening the structural integrity of the wellbore and operational safety.

[0003] Currently, oilfields widely use corrosion inhibitor injection to slow down pipe corrosion. Traditional corrosion inhibitors are mostly based on organic compounds such as amines, imidazolines, and amides. Their molecules can form an adsorption film on the metal surface, thereby isolating the corrosive medium from contact with the metal. However, existing corrosion inhibitors show significant deficiencies in the CO2-H2S coexistence system: on the one hand, some conventional corrosion inhibitors have limited effectiveness in inhibiting H2S-induced sulfide stress corrosion and are prone to failure in high-concentration hydrogen sulfide environments; on the other hand, existing corrosion inhibition systems are highly temperature-sensitive, and their corrosion inhibition efficiency drops sharply under high-temperature well conditions, making it difficult to form a dense, stable protective film layer.

[0004] Therefore, how to develop an efficient corrosion inhibitor formula suitable for the coexistence of CO2 and H2S in a complex corrosive environment is still an important issue that needs to be solved in the current oilfield chemicals field. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist, which has excellent corrosion inhibition effect.

[0006] The present invention provides a corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist, comprising the following raw materials in parts by weight: 1-10 parts of compound A, 1-10 parts of compound B, 1-5 parts of a surfactant, 0.5-1.5 parts of a bactericide, 1-5 parts of an oxygen scavenger, and 80-100 parts of a solvent; The structural formulas of compound A and compound B are shown in formula (I) and formula (II), respectively: 、 .

[0007] Preferably, the preparation method of compound A is as follows: tung oil, triethylenetetramine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction vessel, and then thiourea is added and reacted at 125-165° C. for 8-12 hours to obtain compound A.

[0008] Preferably, the molar ratio of tung oil, triethylenetetramine and thiourea is 1:1-1.5:1-1.2; the dehydration reaction temperature is 140-150° C., and the time is 1-3 hours; and the cyclization reaction temperature is 190-210° C., and the time is 4-8 hours.

[0009] Preferably, the preparation method of compound B is as follows: oleic acid, diethylenetriamine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction vessel, and then benzyl chloride is added and reacted at 85-95° C. for 3-5 hours to obtain compound B.

[0010] Preferably, the molar ratio of oleic acid, diethylenetriamine and benzyl chloride is 1:1-1.5:1-1.5; the dehydration reaction temperature is 140-160° C., and the time is 1-3 hours; and the cyclization reaction temperature is 200-220° C., and the time is 4-8 hours.

[0011] Preferably, the surfactant is sodium cocoyl isethionate.

[0012] Preferably, the fungicide is one or more of quaternary ammonium salt fungicides, metal salt fungicides, biguanide fungicides, glutaraldehyde and thiabendazole.

[0013] Preferably, the oxygen scavenger is one or more of dimethylketoxime, acetaldehyde oxime, diethylhydroxylamine and ascorbic acid.

[0014] Preferably, the solvent is one or more of dimethyl sulfoxide, N,N-dimethylformamide, ethylene glycol, n-pentanol and water.

[0015] Beneficial technical effects of the present invention: In the presence of the surfactant sodium cocoyl isethionate, compound A and compound B exhibit significant synergistic corrosion inhibition performance and good environmental adaptability, effectively addressing the problem of rapid corrosion of oil well tubulars under conditions of high temperature, high pressure, and the coexistence of acidic gases, with a corrosion inhibition rate exceeding 95%. Furthermore, the combination of the bactericide and deoxidizer effectively reduces the synergistic acceleration effect of bacterial-induced corrosion and oxygen corrosion, thereby extending the service life of the tubulars. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to specific embodiments.

[0017] The fungicide in the embodiment of the present invention is quaternary ammonium salt fungicide, which is commercially available; other components in the embodiment of the present invention are also commercially available unless otherwise specified. Example

[0018] The present invention provides a corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist, comprising the following raw materials in parts by weight: 5g of compound A, 5g of compound B, 3g of sodium cocoyl isethionate, 1g of a quaternary ammonium salt fungicide, 3g of dimethyl ketoxime, and 90g of ethylene glycol; The structural formulas of compound A and compound B are shown in formula (I) and formula (II), respectively: 、 ; The preparation method of compound A is as follows: tung oil, triethylenetetramine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction container, and then thiourea is added and reacted at 145° C. for 10 hours to obtain compound A.

[0019] The molar ratio of tung oil, triethylenetetramine and thiourea is 1:1.2:1.1; the dehydration reaction temperature is 145°C and the time is 2h; the cyclization reaction temperature is 200°C and the time is 6h.

[0020] The preparation method of compound B is as follows: oleic acid, diethylenetriamine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction vessel, and then benzyl chloride is added and reacted at 90° C. for 4 hours to obtain compound B.

[0021] The molar ratio of oleic acid, diethylenetriamine and benzyl chloride is 1:1.2:1.2; the dehydration reaction temperature is 150°C and the time is 2 hours; the cyclization reaction temperature is 210°C and the time is 6 hours.

[0022] Example 2 The present invention provides a corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist, comprising the following raw materials in parts by weight: 1g of compound A, 1g of compound B, 1g of sodium cocoyl isethionate, 0.5g of a quaternary ammonium salt fungicide, 1g of acetaldehyde oxime, and 80g of N,N-dimethylformamide; The structural formulas of compound A and compound B are shown in formula (I) and formula (II), respectively.

[0023] The preparation method of compound A is as follows: tung oil, triethylenetetramine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction container, and then thiourea is added and reacted at 125° C. for 8 hours to obtain compound A.

[0024] The molar ratio of tung oil, triethylenetetramine and thiourea is 1:1:1; the dehydration reaction temperature is 140°C and the time is 1 hour; the cyclization reaction temperature is 190°C and the time is 4 hours.

[0025] The preparation method of compound B is as follows: oleic acid, diethylenetriamine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction vessel, and then benzyl chloride is added and reacted at 85° C. for 3 hours to obtain compound B.

[0026] The molar ratio of oleic acid, diethylenetriamine and benzyl chloride is 1:1:1; the dehydration reaction temperature is 140°C and the time is 1 hour; the cyclization reaction temperature is 200°C and the time is 4 hours.

[0027] Example 3 The present invention provides a corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist, comprising the following raw materials in parts by weight: 10 g of compound A, 10 g of compound B, 5 g of sodium cocoyl isethionate, 1.5 g of a quaternary ammonium salt fungicide, 5 g of dimethyl ketoxime, and 100 g of dimethyl sulfoxide; The structural formulas of compound A and compound B are shown in formula (I) and formula (II), respectively.

[0028] The preparation method of compound A is as follows: tung oil, triethylenetetramine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction vessel, and then thiourea is added and reacted at 165° C. for 12 hours to obtain compound A.

[0029] The molar ratio of tung oil, triethylenetetramine and thiourea is 1:1.5:1.2; the dehydration reaction temperature is 150°C and the time is 3 hours; the cyclization reaction temperature is 210°C and the time is 8 hours.

[0030] The preparation method of compound B is as follows: oleic acid, diethylenetriamine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction vessel, and then benzyl chloride is added and reacted at 95° C. for 5 hours to obtain compound B.

[0031] The molar ratio of oleic acid, diethylenetriamine and benzyl chloride is 1:1.5:1.5; the dehydration reaction temperature is 160°C and the time is 3 hours; the cyclization reaction temperature is 220°C and the time is 8 hours.

[0032] Comparative Example 1 The present invention provides a corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist. The corrosion inhibitor comprises the following raw materials in parts by weight: 5 g of compound A, 5 g of compound B, 1 g of a quaternary ammonium salt fungicide, 3 g of dimethyl ketoxime, and 90 g of ethylene glycol.

[0033] The remaining conditions are the same as those in Example 1.

[0034] Comparative Example 2 The present invention provides a corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist. The corrosion inhibitor comprises the following raw materials in parts by weight: 10 g of compound A, 1 g of a quaternary ammonium salt fungicide, 3 g of dimethyl ketoxime, and 90 g of ethylene glycol.

[0035] The remaining conditions are the same as those in Example 1.

[0036] Comparative Example 3 The present invention provides a corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist. The corrosion inhibitor comprises the following raw materials in parts by weight: 10 g of compound B, 1 g of a quaternary ammonium salt fungicide, 3 g of dimethyl ketoxime, and 90 g of ethylene glycol.

[0037] The remaining conditions are the same as those in Example 1.

[0038] Comparative Example 4 The present invention provides a corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist. The corrosion inhibitor comprises the following raw materials in parts by weight: 10 g of compound B, 3 g of sodium cocoyl isethionate, 1 g of a quaternary ammonium salt fungicide, 3 g of dimethyl ketoxime, and 90 g of ethylene glycol.

[0039] The remaining conditions are the same as those in Example 1.

[0040] Comparative Example 5 The present invention provides a corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist. The corrosion inhibitor comprises the following raw materials in parts by weight: 10 g of compound A, 3 g of sodium cocoyl isethionate, 1 g of a quaternary ammonium salt fungicide, 3 g of dimethyl ketoxime, and 90 g of ethylene glycol.

[0041] The remaining conditions are the same as those in Example 1.

[0042] The corrosion inhibition performance of the corrosion inhibitors prepared in Example 1 and Comparative Examples 1-5 was evaluated, and the test results are shown in Table 1.

[0043] Evaluation method: H2S partial pressure 0.5MPa, CO2 partial pressure 1.0MPa, corrosion inhibitor concentration 200ppm, test temperature 80℃, time 72h, test material N80 steel.

[0044] Table 1 Corrosion inhibition performance evaluation results Group Corrosion inhibition rate (%) Example 1 96.53 Comparative Example 1 80.32 Comparative Example 2 81.17 Comparative Example 3 77.69 Comparative Example 4 89.74 Comparative Example 5 87.46 As can be seen from the test results of Example 1 in Table 1, the corrosion inhibitor of the present invention has an excellent corrosion inhibition effect. As can be seen from the test results of Example 1 and Comparative Examples 1-5, in the presence of the surfactant sodium cocoyl isethionate, Compound A and Compound B of the present invention have significant synergistic corrosion inhibition performance and good environmental adaptability, and can effectively solve the problem of rapid corrosion of oil well tubular goods under conditions of high temperature, high pressure, and the coexistence of acidic gases.

[0045] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents, and all should be included in the scope of protection of the present application.

Claims

1. A corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist, characterized in that: The invention comprises the following raw materials in parts by weight: 1-10 parts of compound A, 1-10 parts of compound B, 1-5 parts of surfactant, 0.5-1.5 parts of bactericide, 1-5 parts of deoxidizer and 80-100 parts of solvent; The structural formulas of compound A and compound B are shown in formula (I) and formula (II), respectively: ; 。 2. The corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 1, characterized in that: The preparation method of compound A is as follows: tung oil, triethylenetetramine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction container, and then thiourea is added and reacted at 125-165° C. for 8-12 hours to obtain compound A.

3. The corrosion inhibitor for inhibiting the corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 2, characterized in that: The molar ratio of tung oil, triethylenetetramine and thiourea is 1:1-1.5:1-1.2; the dehydration reaction temperature is 140-150° C., and the time is 1-3 hours; the cyclization reaction temperature is 190-210° C., and the time is 4-8 hours.

4. The corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 1, characterized in that: The preparation method of compound B is as follows: oleic acid, diethylenetriamine and xylene are sequentially subjected to dehydration reaction and cyclization reaction in a reaction vessel, and then benzyl chloride is added and reacted at 85-95° C. for 3-5 hours to obtain compound B.

5. The corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 4, characterized in that: The molar ratio of oleic acid, diethylenetriamine and benzyl chloride is 1:1-1.5:1-1.5; the dehydration reaction temperature is 140-160° C., and the time is 1-3 hours; the cyclization reaction temperature is 200-220° C., and the time is 4-8 hours.

6. The corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 1, characterized in that: The surfactant is sodium cocoyl isethionate.

7. The corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 1, characterized in that: The bactericide is one or more of quaternary ammonium salt bactericide, metal salt bactericide, biguanide bactericide, glutaraldehyde and thiabendazole.

8. The corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 1, characterized in that: The oxygen scavenger is one or more of dimethyl ketoxime, acetaldehyde oxime, diethylhydroxylamine and ascorbic acid.

9. The corrosion inhibitor for inhibiting corrosion of oil well pipes in a system where carbon dioxide and hydrogen sulfide coexist according to claim 1, characterized in that: The solvent is one or more of dimethyl sulfoxide, N,N-dimethylformamide, ethylene glycol, n-pentanol and water.

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