Bis-Mannich base corrosion inhibitor for oil field as well as preparation method and application thereof

Abstract

The invention relates to a bis-Mannich base corrosion inhibitor for an oil field and a preparation method thereof.The preparation method comprises the following steps that an amine compound and an organic solvent are added into a reaction flask, and after the amine compound and the organic solvent are fully dissolved, a catalyst is added to adjust the pH value of the solution to 2-10; heating the solution to 55-85 DEG C, then adding a formaldehyde compound and a carbonyl compound, and then carrying out heat preservation reaction for 5-9 hours; and after the reaction is finished, removing the organic solvent to obtain the bis-Mannich base corrosion inhibitor for the oil field. The bis-Mannich base corrosion inhibitor has an excellent corrosion inhibition effect, also has good acid solubility, can meet the corrosion inhibition requirement of fracture acidification, can be used as a corrosion inhibitor in an oil well pipe sleeve, and greatly prolongs the service life of the oil well pipe sleeve. Meanwhile, the bis-Mannich base corrosion inhibitor is mild in preparation reaction condition and easy to separate, and can be applied to the fields of industrial cooling water, acid pickling, oil and gas well acidification and the like.

Description

Technical Field

[0001] The invention relates to the technical field of Mannich base corrosion inhibitors, and in particular to a preparation method and application of a double Mannich base corrosion inhibitor for oil fields. Background Art

[0002] As oilfield development enters the middle and late stages, oil well casing damage has become the main factor restricting oilfield cost reduction and efficiency improvement. Under the complex fluid medium and temperature and pressure conditions downhole, as the oil and gas well production time increases, metal production tubing such as casing and oil pipe will show varying degrees of corrosion, which can cause deformation and perforation of oil well casing, leading to major safety accidents and economic losses.

[0003] A corrosion inhibitor is a chemical agent that can effectively prevent or slow down corrosion when it exists in a corrosive medium (environment) at an appropriate concentration. This chemical agent is usually a mixture of one or several compounds. Generally speaking, a corrosion inhibitor is a substance that can protect the metal surface. It usually does so by forming a protective film on the metal surface. At the same time, the addition of corrosion inhibitors can also keep the mechanical and physical properties of the metal unchanged, and will hardly have a negative impact on the medium (environment). Due to the advantages of adding corrosion inhibitors to the medium (environment), such as good effect, high economic benefits, and small amount of drugs, it has become one of the most commonly used methods in anti-corrosion technology. Especially in the oil and gas field industry, corrosion inhibitors have become one of the main means of protection.

[0004] Mannich bases contain polar groups that can coordinate with the empty d orbitals of metals and form adsorption on the metal surface, thereby forming a protective film on the metal-medium (environment) interface to prevent or slow down the corresponding electrochemical corrosion and protect the metal surface from corrosion. Therefore, Mannich bases are usually an adsorption-type corrosion inhibitor. However, existing Mannich base corrosion inhibitors have the characteristic of weak adsorption at high temperatures. Bis-Mannich bases contain more active sites than mono-Mannich bases and can produce stronger adsorption on metal surfaces, which is expected to solve the problem of difficulty in adsorption of Mannich base corrosion inhibitors on metal surfaces. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a double Mannich base corrosion inhibitor for oil fields and a preparation method and application thereof, so as to inhibit the corrosion of metals under various complex conditions.

[0006] Different from the prior art, the above technical solution provides a dual Mannich base corrosion inhibitor for oil fields, the structure of which is shown in Formula 1:

[0007]

[0008] Among them, the R 1 and R2 -CH 2 CH 2 OH or H; R 3 -H 2 , or one of the R 3 -CH 2 -, another R 3 -CH 2 CH 2 -, and two R 3 are connected.

[0009] The double Mannich base shown in Formula 1 disclosed in the present invention contains C=O and two CN bonds, and can form a strong coordination effect with the empty d orbital of the metal through a coordination bond, so that the double Mannich base molecules are tightly combined with the metal to form a strong adsorption film, which blocks the contact between corrosive particles and the metal surface, thereby inhibiting metal corrosion and having a good anti-corrosion effect on the metal.

[0010] The present invention also provides a method for preparing a dual Mannich base corrosion inhibitor for oil fields, which comprises the following steps:

[0011] Add amine compounds and organic solvents to the reaction flask, add catalysts after fully dissolving, and adjust the pH value of the solution to 2-10;

[0012] The solution is heated to 55-85° C., and then formaldehyde compounds and carbonyl compounds are added, followed by heat preservation for reaction for 5-9 hours. After the reaction is completed, the organic solvent is removed to obtain the di-Mannich base corrosion inhibitor for oil fields, wherein the molar ratio of the amine compounds, the formaldehyde compounds and the carbonyl compounds is 1-1.2:0.5:1-1.2.

[0013] The double Mannich base corrosion inhibitor of the present invention adopts the above-mentioned preparation method, and the reaction conditions are mild and easy to separate. At the same time, the prepared double Mannich base corrosion inhibitor does not need further separation and purification, and can be directly added to the corrosive medium, and the corrosion inhibition performance of the prepared double Mannich base is evaluated according to the petroleum industry standard SY / T5405-2019 "Performance Test Method and Evaluation Index of Corrosion Inhibitor for Acidification".

[0014] The double Mannich base corrosion inhibitor prepared by the invention can be applied to the fields of industrial cooling water, pickling, oil and gas well acidizing, etc.

[0015] Furthermore, the carbonyl compound is one or a mixture of two or more of the following: acetone, cyclohexanone and acetophenone. The carbonyl compound selected in the present invention has a simple chemical structure, and the hydrogen on the carbon atom connected to both sides of the C=O double bond is moderately active and easy to remove.

[0016] Furthermore, the amine compound is ethanolamine or diethanolamine. Since ethanolamine or diethanolamine can provide active sites and have moderate reactivity, it is convenient to control the reaction rate; at the same time, ethanolamine or diethanolamine also has the advantages of good solubility, low cost, easy procurement, convenient post-processing, etc.

[0017] Furthermore, the formaldehyde compound is one of the following: paraformaldehyde, formaldehyde, a compound that can decompose formaldehyde; the compound that can decompose formaldehyde is one of the following: hexamethylenetetramine, phenolic resin, urea-formaldehyde resin. The compound that can decompose formaldehyde not only does not have the pungent smell of formaldehyde, but can also play the role of formaldehyde and can replace formaldehyde to participate in the Mannich reaction.

[0018] Furthermore, the organic solvent is one of the following: anhydrous ethanol, anhydrous methanol, and acetic acid.

[0019] Furthermore, the specific operation of removing the organic solvent is: using a rotary evaporator to remove the organic solvent at 60-85°C.

[0020] Furthermore, the catalyst is one of the following: concentrated hydrochloric acid with a concentration of 10% and a sodium hydroxide aqueous solution with a concentration of 5 mol / L.

[0021] The invention also discloses application of the double Mannich base corrosion inhibitor for oil fields. The double Mannich base corrosion inhibitor for oil fields is applied as a corrosion inhibitor for inhibiting metal corrosion.

[0022] The beneficial effects of the present invention are as follows: in view of the technical problem that the existing Mannich base corrosion inhibitor has a low adsorption effect, the double Mannich base prepared by the present invention contains C=O and two CN bonds, and can form a strong coordination effect with the empty d orbital of the metal through a coordination bond, so that the double Mannich base molecules are tightly combined with the metal to form a strong adsorption film, which blocks the contact between corrosive particles and the metal surface, thereby effectively inhibiting metal corrosion.

[0023] The double Mannich base corrosion inhibitor of the present invention has both excellent corrosion inhibition effect and good acid solubility, can meet the corrosion inhibition requirements of fracturing acidification, can be used as a corrosion inhibitor in oil well casings, and greatly prolongs the service life of oil well casings. At the same time, the preparation reaction conditions of the double Mannich base corrosion inhibitor of the present invention are mild, easy to separate, and can be applied to the fields of industrial cooling water, pickling, oil and gas well acidification, etc. DETAILED DESCRIPTION

[0024] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments.

[0025] Example 1

[0026] The bis-Mannich base corrosion inhibitor A prepared in this example has a structure shown in Formula 2:

[0027]

[0028] The preparation method of the dual Mannich base corrosion inhibitor A of this embodiment comprises the following steps:

[0029] In a 250mL three-necked flask, 0.012mol / L diethanolamine was added, and the pH value of the solution was adjusted to 2 with 20mL of 10% concentrated hydrochloric acid as a catalyst, and anhydrous ethanol was added as an organic solvent, the mass of which was 5 times the mass of diethanolamine. When the temperature was raised to 75°C, cyclohexanone and formaldehyde were added continuously, and the molar ratio of the added diethanolamine, cyclohexanone and formaldehyde was 1.2:0.5:1.1. After the reaction was kept warm for 6 hours under stirring, the anhydrous ethanol was evaporated at 80°C by a rotary evaporator to obtain the bis-Mannich base A. The corrosion inhibition performance evaluation results are shown in Table 1.

[0030] The reaction formula of the dual Mannich base corrosion inhibitor A of this embodiment is as follows:

[0031]

[0032] The synthesized crude product was purified by silica gel flash column chromatography (chloroform: methanol = 8: 1) to obtain a product for structural characterization and performance evaluation.

[0033] NMR spectra were recorded in deuterated chloroform solutions on a Bruker DPX 300 spectrometer with 1H NMR operating at 400 MHz. Mass spectra were recorded on a Micromass Platform II spectrometer with a direct inlet system operating in electron impact (EI) mode.

[0034] Bis-Mannich Base A: 1 H-NMR (CDCl 3 , 400MHz): δ4.16 (s, 4H), 3.42 (t, 4H), 2.55 (t, 4H), 2.71; 2.46 (m, 2H), 2.17 (m, 2H), 1.92; 1.67 (t, 2H), 1.80; 1.70 (m, 1H); m / z: 333.24. The molecular weight of the product is close to that of the target product, indicating that the bis-Mannich base A has been successfully synthesized.

[0035] Example 2

[0036] The bis-Mannich base corrosion inhibitor B prepared in this example has a structure shown in Formula 4:

[0037]

[0038] The preparation method of the dual Mannich base corrosion inhibitor B of this embodiment comprises the following steps:

[0039] In a 250mL three-necked flask, 0.011mol / L ethanolamine was added, 20mL of a 5mol / L sodium hydroxide aqueous solution as a catalyst was used to adjust the pH value to 9, anhydrous ethanol was added as an organic solvent, and the mass of the organic solvent added was 10 times the mass of ethanolamine. When the temperature was raised to 85°C, cyclohexanone and formaldehyde were continuously added, and the molar ratio of the added ethanolamine, cyclohexanone and formaldehyde was 1.0:0.5:1.0. After the reaction was kept warm for 6 hours under stirring, anhydrous ethanol was evaporated at 85°C by a rotary evaporator to obtain a bis-Mannich base B. The corrosion inhibition performance evaluation results are shown in Table 1.

[0040] The synthesis reaction formula of the dual Mannich base corrosion inhibitor B of this embodiment is as shown in Formula 5:

[0041]

[0042] The synthesized crude product was purified by silica gel flash column chromatography (chloroform: methanol = 7: 1) to obtain a product for structural characterization and performance evaluation.

[0043] NMR spectra were recorded in deuterated chloroform solutions on a Bruker DPX 300 spectrometer with 1H NMR operating at 400 MHz. Mass spectra were recorded on a Micromass Platform II spectrometer with a direct inlet system operating in electron impact (EI) mode.

[0044] Bis-Mannich base B: 1 H-NMR (CDCl 3 , 400MHz): δ4.81(s, 2H), 3.48(t, 2H), 2.74(t, 2H), 3.7(s, 2H), 2.9; 2.65(m, 2H), 2.17(m, 2H), 1.80; 1.70(m, 1H), 1.92; 1.67(m, 2H); m / z: 231.17. The molecular weight of the product is close to that of the target product, indicating that the bis-Mannich base B has been successfully synthesized.

[0045] Example 3

[0046] The bis-Mannich base corrosion inhibitor C prepared in this example has a structure shown in Formula 6:

[0047]

[0048] The preparation method of the dual Mannich base corrosion inhibitor C of this embodiment comprises the following steps:

[0049] In a 250mL three-necked flask, 0.011mol / L ethanolamine was added, 10mL of 10% concentrated hydrochloric acid was used as a catalyst to adjust the solution pH to 5, anhydrous methanol was added as an organic solvent, the mass of the organic solvent added was 5 times the mass of ethanolamine, and when the temperature was raised to 55°C, acetone and hexamethylenetetramine were added (the decomposed formaldehyde participated in the reaction), the molar ratio of the added ethanolamine, acetone, and hexamethylenetetramine was 1.1:0.5:1.2, and after the reaction was kept warm for 8h under stirring, anhydrous methanol was removed at 60°C by a rotary evaporator to obtain bis-Mannich base C. The corrosion inhibition performance evaluation results are shown in Table 1.

[0050] The synthesis reaction formula of the dual Mannich base corrosion inhibitor C of this embodiment is as shown in Formula 7:

[0051]

[0052] The synthesized crude product was purified by silica gel flash column chromatography (chloroform: methanol = 10: 1) to obtain a product for structural characterization and performance evaluation.

[0053] NMR spectra were recorded in deuterated chloroform solutions on a Bruker DPX 300 spectrometer with 1H NMR operating at 400 MHz. Mass spectra were recorded on a Micromass Platform II spectrometer with a direct inlet system operating in electron impact (EI) mode.

[0054] Bis-Mannich Base C: 1 H-NMR (CDCl 3 , 400MHz): δ4.81(s, 2H), 3.48(t, 2H), 2.74(t, 2H), 3.7(s, 2H), 2.83(t, 2H), 2.57(t, 2H); m / z: 205.155. The molecular weight of the product is close to that of the target product, indicating that the bis-Mannich base C has been successfully synthesized.

[0055] Example 4

[0056] The bis-Mannich base corrosion inhibitor D prepared in this example has a structure shown in Formula 8:

[0057]

[0058] The preparation method of the dual Mannich base corrosion inhibitor D of this embodiment comprises the following steps:

[0059] In a 250mL three-necked flask, 0.012mol / L diethanolamine was added, and the pH value was adjusted to 7 with 5mL of 10% concentrated hydrochloric acid as a catalyst, and anhydrous methanol was added as an organic solvent, the mass of which was 15 times the mass of diethanolamine. When the temperature was raised to 60°C, acetone and hexamethylenetetramine were added (the decomposed formaldehyde participated in the reaction), and the molar ratio of the added diethanolamine, acetone, and hexamethylenetetramine was 1.2:0.5:1.2. After the reaction was kept warm for 5h under stirring, anhydrous methanol was evaporated at 65°C by a rotary evaporator to obtain bis-Mannich base D. The corrosion inhibition performance evaluation results are shown in Table 1.

[0060] The synthesis reaction formula of the dual Mannich base corrosion inhibitor D of this embodiment is as shown in Formula 9:

[0061]

[0062] The synthesized crude product was purified by silica gel flash column chromatography (chloroform: methanol = 5: 1) to obtain a product for structural characterization and performance evaluation.

[0063] NMR spectra were recorded in deuterated chloroform solutions on a Bruker DPX 300 spectrometer with 1H NMR operating at 400 MHz. Mass spectra were recorded on a Micromass Platform II spectrometer with a direct inlet system operating in electron impact (EI) mode.

[0064] Bis-Mannich base D: 1 H-NMR (CDCl 3 , 400 MHz): δ4.16 (s, 4H), 3.42 (t, 4H), 2.57 (m, 6H), 3.65 (m, 2H); m / z: 293.207. The molecular weight of the product was close to that of the target product, indicating that the bis-Mannich base D had been successfully synthesized.

[0065] Comparative Example 1

[0066] The mono-Mannich base corrosion inhibitor E prepared in this comparative example has a structure shown in Formula 10:

[0067]

[0068] The preparation method of the mono-Mannich base corrosion inhibitor E of this embodiment comprises the following steps:

[0069] In a 100mL three-necked flask, 0.006mol / L diethanolamine was added, and the pH value of the solution was adjusted to 2 with 20mL of 10% concentrated hydrochloric acid as a catalyst, and anhydrous ethanol was added as an organic solvent, the mass of which was 5 times the mass of diethanolamine. When the temperature was raised to 75°C, cyclohexanone and formaldehyde were added, and the molar ratio of the added diethanolamine, cyclohexanone and formaldehyde was 0.6:0.5:0.55. After the reaction was kept warm for 6 hours, the anhydrous ethanol was evaporated at 80°C by a rotary evaporator to obtain a mono-Mannich base E. The corrosion inhibition performance evaluation results are shown in Table 2.

[0070] Comparative Examples 2-4

[0071] Similar to Comparative Example 1, the preparation method of Comparative Example 2-4 refers to Example 2-4, except that the molar number of the input of the amine compound and the formaldehyde compound is reduced by half, and the remaining steps and the input amount of other raw materials are respectively consistent with Examples 2-4 (i.e., the remaining steps and raw material input amount of Comparative Example 2 are the same as those of Example 2, the remaining steps and raw material input amount of Comparative Example 3 are the same as those of Example 3, and the remaining steps and raw material input amount of Comparative Example 4 are the same as those of Example 4), and the control product mono-Mannich base FD (Formula 11-13) is obtained, but because the mono-Mannich base has fewer active sites and cannot form a conjugated structure, the coordination effect with the empty d orbital of the metal is relatively weak. Therefore, the corrosion inhibition performance at 90°C is weaker than that of the bis-Mannich base, and the experimental results are shown in Table 2.

[0072]

[0073] Experimental example

[0074] The corrosion inhibition performance of the double Mannich base AD in Examples 1-4 and the single Mannich base EH in Comparative Examples 1-4 was evaluated. The corrosion rate and corrosion inhibition rate of the double Mannich base corrosion inhibitor of the present invention were determined according to the normal pressure static corrosion rate, corrosion inhibition rate determination method and evaluation index in the petroleum industry standard SY / T5405-2019 "Performance Test Method and Evaluation Index of Corrosion Inhibitors for Acidification", and the test conditions are as follows:

[0075] Refer to the test conditions of static corrosion rate and corrosion inhibition rate at normal pressure and evaluation index: steel sheet material: Q235, evaluation temperature: 90°C, evaluation time: 4h, corrosion inhibitor addition amount is 0.1% of the volume of the acid solution, and the acid solution is 5wt% hydrochloric acid. During the experiment, it was found that the double Mannich base corrosion inhibitor AD prepared in Examples 1-4 of the present invention has good solubility and can be well dispersed in the corrosive medium without adding a dispersant. The test results are shown in Table 1. The single Mannich base EH was prepared in the comparative example. Since the single Mannich base has fewer active sites and cannot form a conjugated structure, the coordination effect with the empty d orbital of the metal is relatively weak. The test results are shown in Table 2.

[0076] Table 1 Results of static corrosion tests of corrosion inhibitors at normal pressure in Examples 1-4

[0077] Serial number Corrosion Inhibitor <![CDATA[Corrosion rate (g / m 2 ·h)]]> Corrosion inhibition rate (%) 1 Bis-Mannich Base A 2.62 89.69 2 Bis-Mannich base B 2.21 92.61 3 Bis-Mannich Base C 1.86 92.66 4 Bis-Mannich Base D 2.56 74.96

[0078] Table 2 Comparative Examples 1-4 Static Corrosion Test Results of Corrosion Inhibitors at Normal Pressure

[0079] Serial number Corrosion Inhibitor <![CDATA[Corrosion rate (g / m 2 ·h)]]> Corrosion inhibition rate (%) 1 MonoMannich Base E 5.77 81.01 2 Mono-Mannich Base F 5.63 75.43 3 MonoMannich Base G 2.53 83.25 4 Mono-Mannich base H 4.93 61.86

[0080] It can be seen from the results listed in Table 1 and Table 2 that the double Mannich base corrosion inhibitor of the present invention has excellent corrosion inhibition effect in an acidified environment and at high temperature. The corrosion inhibition effect of the single Mannich base prepared in the comparative example at high temperature is weaker than that of the double Mannich base, because the double Mannich base has more active sites than the single Mannich base, and can produce stronger and more stable adsorption on the metal surface, thereby better inhibiting metal corrosion.

[0081] The preparation method of the dual Mannich base corrosion inhibitor of the present invention has a Mannich reaction mechanism, and the Mannich reaction is a three-component condensation reaction of amine, aldehyde and ketone. Since the steric hindrance of the dual Mannich base corrosion inhibitor of the present invention is significantly greater than that of the single Mannich base synthesized with the same raw materials, the space occupied on the metal surface becomes larger, and the corrosion of corrosive ions can be more effectively prevented.

[0082] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "include..." or "comprise..." do not exclude the existence of other elements in the process, method, article or terminal device including the elements. In addition, in this article, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself.

[0083] Although the above embodiments have been described in this article, the patent protection scope of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, changes and modifications made to the embodiments described herein, or equivalent structures or equivalent process changes made using the contents of the present invention specification, directly or indirectly applying the above technical solutions to other related technical fields are all included in the patent protection scope of the present invention.

Claims

1. A bis-Mannich base corrosion inhibitor for oil fields, characterized in that: Its structure is shown in formula 1: Wherein, R1 and R2 are -CH2CH2OH or H respectively; R3 is -H2, or one R3 is -CH2- and the other R3 is -CH2CH2-, and the two R3s are connected.

2. The method for preparing a bis-Mannich base corrosion inhibitor for oil fields according to claim 1, characterized in that: It includes the following steps: Add amine compounds and organic solvents to the reaction flask, add catalysts after fully dissolving, and adjust the pH value of the solution to 2-10; The solution is heated to 55-85° C., and then formaldehyde compounds and carbonyl compounds are added, followed by heat preservation for reaction for 5-9 hours. After the reaction is completed, the organic solvent is removed to obtain the di-Mannich base corrosion inhibitor for oil fields, wherein the molar ratio of the amine compounds, the formaldehyde compounds and the carbonyl compounds is 1-1.2:0.5:1-1.

2.

3. The method for preparing a double Mannich base corrosion inhibitor for oil fields according to claim 2, characterized in that: The carbonyl compound is one or a mixture of two or more of the following: acetone, cyclohexane or phenethyl.

4. The method for preparing a bis-Mannich base corrosion inhibitor for oil fields according to claim 2, characterized in that: The amine compound is ethanolamine or diethanolamine.

5. The method for preparing a bis-Mannich base corrosion inhibitor for oil fields according to claim 2, characterized in that: The formaldehyde compound is one of the following: paraformaldehyde, formaldehyde, and a compound capable of decomposing formaldehyde; the compound capable of decomposing formaldehyde is one of the following: hexamethylenetetramine, phenolic resin, and urea-formaldehyde resin.

6. The method for preparing a bis-Mannich base corrosion inhibitor for oil fields according to claim 2, characterized in that: The organic solvent is one of the following: anhydrous ethanol, anhydrous methanol, or acetic acid.

7. The method for preparing a bis-Mannich base corrosion inhibitor for oil fields according to claim 2, characterized in that: The specific operation of removing the organic solvent is: using a rotary evaporator to remove the organic solvent at 60-85°C.

8. The method for preparing a bis-Mannich base corrosion inhibitor for oil fields according to claim 2, characterized in that: The catalyst is one of the following: concentrated hydrochloric acid, sodium hydroxide aqueous solution.

9. The use of a double Mannich base corrosion inhibitor for oil fields according to claim 1, characterized in that: The oil field dual Mannich base corrosion inhibitor is used as a corrosion inhibitor for inhibiting metal corrosion.

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