Multi-element compound corrosion inhibitor for offshore CO2 oil displacement as well as preparation method and application of multi-element compound corrosion inhibitor

Abstract

The invention relates to a multi-element compound corrosion inhibitor for offshore CO2 oil displacement as well as a preparation method and application of the multi-element compound corrosion inhibitor. The invention relates to a multi-element compound corrosion inhibitor for offshore CO2 oil displacement, which is characterized by comprising 8 to 10 weight percent of oleic acid imidazoline quaternary ammonium salt, 8 to 10 weight percent of oleic acid imidazoline lauric acid amide, 4 to 6 weight percent of potassium iodide, 4 to 6 weight percent of octylphenol polyoxyethylene ether, 4 to 6 weight percent of dodecyl dimethyl tertiary amine, 4 to 6 weight percent of assistant A, 4 to 6 weight percent of assistant B and the balance of absolute ethyl alcohol. According to the multi-element compound corrosion inhibitor for offshore CO2 oil displacement as well as the preparation method and the application of the multi-element compound corrosion inhibitor, the multi-element compound corrosion inhibitor contains a plurality of components and can effectively inhibit CO2 corrosion at a high temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum corrosion inhibitors, and specifically relates to a multi-component composite corrosion inhibitor for offshore CO2 oil recovery, and a preparation method and application thereof. Background Art

[0002] Offshore CO2 capture, utilization and storage technology is an important technology for the green and low-carbon transformation of my country's offshore oil and gas development. However, after CO2 is injected, a part of it slowly dissolves in the formation water to form carbonic acid. The produced water from the high-salinity oilfield containing carbonic acid corrodes the offshore platform facilities and submarine pipelines, resulting in huge economic losses and safety hazards. Therefore, the task of corrosion and protection of offshore oil and gas fields has always been one of the important tasks of the petroleum industry.

[0003] Among the many anti-corrosion measures for offshore oil fields, adding corrosion inhibitors is the most economical and effective. The earliest corrosion inhibitors used were nitrites, chromates, molybdates, etc. They form an oxide film on the metal surface and inhibit corrosion through oxidation-reduction reactions. Although chromates and other corrosion inhibitors have good corrosion inhibition effects, their toxicity is relatively high, and their use is restricted in offshore operating environments with increasingly stringent environmental protection requirements, and they have been replaced by other corrosion inhibitors. At present, the corrosion inhibitors used in oil and gas field exploitation are mainly low-toxic organic corrosion inhibitors such as imidazolines, aldehydes, ketones, alkynols, pyridines, quinolines, quaternary ammonium salts, amides, and imidazolines.

[0004] Currently, the most widely used corrosion inhibitors are mainly imidazoline corrosion inhibitors. The nitrogen atoms and other polar groups in the molecular structure of imidazoline corrosion inhibitors can be adsorbed on the metal surface to form a monolayer or multilayer protective film, which effectively prevents the erosion of corrosive media. Imidazoline corrosion inhibitors have the following main advantages: (1) In a CO2 corrosion environment, they can effectively reduce the corrosion rate of metal equipment; (2) They can adapt to different offshore oil reservoir corrosion temperature ranges; (3) Corrosion inhibitors need to be effective in high-salt environments (salinity may reach about 3-5%); (4) They have good biodegradability and can avoid long-term pollution to the marine ecosystem.

[0005] CN109112548B discloses a corrosion inhibitor for gathering and transportation pipelines against CO2 corrosion, which comprises 50-60% of bisimidazoline quaternary ammonium salt, 10-40% of alkyl / aromatic sodium dithiocarbamate, and 10-40% of solvent by mass percentage. The invention solves the problem of serious corrosion of gathering and transportation pipelines in CO2 enhanced oil recovery technology, thereby greatly extending the service life of crude oil gathering and transportation pipelines. However, the working temperature of the corrosion inhibitor of the invention is 80°C, which cannot meet the anti-corrosion requirements under harsh working conditions of higher temperature and high salt.

[0006] In view of this, the present invention proposes a new multi-component composite corrosion inhibitor for offshore CO2 oil recovery and its preparation method and application. It has good high temperature resistance, can achieve higher corrosion inhibition performance under high salt conditions, and can be used for corrosion protection of CO2 in produced water of offshore high-salinity oil fields. Summary of the invention

[0007] The purpose of the invention is to provide a multi-component corrosion inhibitor for offshore CO2 oil recovery. The corrosion inhibitor introduces imidazoline rings, quaternary ammonium cation groups, and amide bonds, which increase the binding energy between the corrosion inhibitor molecules and the metal surface and improve the solubility of the corrosion inhibitor molecules in water. The multi-component formulation enables the corrosion inhibitor to form a denser protective film with the metal surface, thereby preventing the contact between the corrosion particles and the metal and reducing the further occurrence of corrosion, ensuring a high anti-corrosion effect under the conditions of a temperature of 90°C, a salinity of about 3-5%, and a CO2-rich environment.

[0008] In order to achieve the above purpose, the technical solution adopted is:

[0009] A multi-component composite corrosion inhibitor for offshore CO2 flooding comprises: 8-10wt% of oleic acid imidazoline quaternary ammonium salt, 8-10wt% of oleic acid imidazoline lauric acid amide, 4-6wt% of potassium iodide, 4-6wt% of octylphenol polyoxyethylene ether, 4-6wt% of dodecyl dimethyl tertiary amine, 4-6wt% of auxiliary agent A, 4-6wt% of auxiliary agent B, and the rest is supplemented to 100wt% by anhydrous ethanol.

[0010] Furthermore, the auxiliary agent A is one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

[0011] The auxiliary agent B is one of sodium dodecylbenzene sulfonate, thiourea and fatty alcohol polyoxyethylene ether.

[0012] Further, the structural formula of the oleic acid imidazoline quaternary ammonium salt is as follows:

[0013]

[0014] The structural formula of the oleic acid imidazoline lauric acid amide is as follows:

[0015]

[0016] Another object of the present invention is to provide a method for preparing the above-mentioned multi-component composite corrosion inhibitor, which is simple and has low production cost.

[0017] In order to achieve the above purpose, the technical solution adopted is:

[0018] The preparation method of the above-mentioned multi-component compound corrosion inhibitor is:

[0019] After uniformly mixing oleic acid imidazoline quaternary ammonium salt, oleic acid imidazoline lauric acid amide and anhydrous ethanol at 45-55°C, potassium iodide was added and stirred until dissolved, and then auxiliary agent A was added and stirred until dissolved. The solution turned yellow to obtain a mixed solution 1;

[0020] Octylphenol polyoxyethylene ether is added to the mixed solution 1, stirred until dissolved, and then the additive B is added. After mixing evenly at 50-55° C., dodecyl dimethyl tertiary amine is added and mixed evenly to obtain the multi-component corrosion inhibitor.

[0021] Furthermore, the preparation method of the oleic acid imidazoline quaternary ammonium salt is as follows: oleic acid imidazoline, benzyl chloride, and solvent xylene are stirred in a nitrogen atmosphere at 110-120° C. for 3-4 hours, and xylene is removed to obtain the oleic acid imidazoline quaternary ammonium salt;

[0022] The preparation method of the oleic acid imidazoline lauric acid amide is as follows: oleic acid imidazoline, lauric acid, and solvent xylene are stirred for reaction at 110-120° C. for 3-4 hours under nitrogen protection, and xylene is removed to obtain the oleic acid imidazoline lauric acid amide;

[0023] Further, the preparation method of the oleic acid imidazoline is:

[0024] The solvent xylene, oleic acid and tetraethylenepentamine are refluxed for 4-5 hours at 140-150° C. under nitrogen protection, and the reflux reaction is terminated after the water generated by the reaction is separated; the reaction is then continued at 210-220° C. until the actual dehydration amount is more than 85% of the theoretical dehydration amount, and the xylene is removed to obtain oleic acid imidazoline.

[0025] Furthermore, the molar ratio of the oleic acid imidazoline to the benzyl chloride is 1:1-1.2;

[0026] The molar ratio of oleic acid imidazoline to lauric acid is 1:1-1.2;

[0027] The molar ratio of oleic acid to tetraethylenepentamine is 1:1.2-1.4.

[0028] Furthermore, the molar ratio of the oleic acid imidazoline to the benzyl chloride is 1:1.1;

[0029] The molar ratio of oleic acid imidazoline to lauric acid is 1:1.1;

[0030] The molar ratio of oleic acid to tetraethylenepentamine is 1:1.3.

[0031] Another object of the present invention is to provide the use of the above-mentioned multi-component composite corrosion inhibitor in offshore CO2 oil recovery.

[0032] The application of the above-mentioned multi-component compound corrosion inhibitor in offshore CO2 oil recovery.

[0033] Furthermore, the working temperature of the multi-component corrosion inhibitor is 90°C.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. In the technical solution of the present invention, the corrosion inhibitor introduces an imidazoline ring, a quaternary ammonium cation group, and an amide bond, which increases the binding energy between the corrosion inhibitor molecules and the metal surface, improves the solubility of the corrosion inhibitor molecules in water, and the multi-component compounding enables the corrosion inhibitor and the metal surface to form a denser protective film, thereby preventing the contact between the corrosion particles and the metal and reducing the further occurrence of corrosion, ensuring a high anti-corrosion effect under the conditions of a temperature of 90°C, a salinity of about 3-5%, and a CO2-rich environment.

[0036] 2. In the technical solution of the present invention, the multi-component composite corrosion inhibitor can be used for corrosion protection of CO2 in produced water from offshore high-salinity oil fields. It has good high temperature resistance and can achieve higher corrosion inhibition performance under high-salinity conditions. The corrosion inhibition effect achieved is higher than the industry standard (SY / T 5273-2014), and the corrosion inhibition efficiency for Q235 carbon steel is above 90%.

[0037] 3. In the technical solution of the present invention, the preparation method of the corrosion inhibitor has the advantages of simple synthesis method, low production cost and significant corrosion resistance, and is suitable for the high-salt oilfield produced water environment containing CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Synthesis route of oleic acid imidazoline quaternary ammonium salt.

[0039] Figure 2 Synthesis route of oleic acid imidazoline lauric acid amide.

[0040] Figure 3 These are SEM images of the corrosion morphology of the iron sheets after corrosion: (a) blank, (b) example 3, (c) example 2, and (d) example 6.

[0041] Figure 4 IR spectrum of oleic acid imidazoline quaternary ammonium salt (H).

[0042] Figure 5 IR spectrum of oleic acid imidazoline lauric acid amide (Y). DETAILED DESCRIPTION

[0043] In order to further explain the multi-component corrosion inhibitor for offshore CO2 oil recovery and its preparation method and application of the present invention, and to achieve the intended purpose of the invention, the following is a detailed description of the multi-component corrosion inhibitor for offshore CO2 oil recovery proposed in accordance with the present invention and its preparation method and application, its specific implementation method, structure, characteristics and efficacy, in combination with the preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0044] The following will further introduce in detail the multi-component composite corrosion inhibitor for offshore CO2 flooding and its preparation method and application in conjunction with specific embodiments:

[0045] With the increasing development of my country's offshore CO2 capture, utilization and storage technology, green and low-carbon offshore oil and gas development has become a transformation of offshore oil and gas resource development. The major problem facing offshore oil and gas development is that the reservoir temperature and water salinity are getting higher and higher with the increase of mining depth, resulting in serious corrosion of gathering and transportation pipelines. However, there are currently few corrosion inhibitors suitable for the corrosion protection of gathering and transportation pipelines under high temperature conditions, especially multi-component corrosion inhibitors for gathering and transportation pipelines in a temperature of 90°C and a high salinity environment have not yet been reported.

[0046] In order to solve the above problems, the present invention provides a high temperature and high salt corrosion inhibitor, a preparation method and its application in the corrosion protection of offshore oil and gas gathering and transportation pipelines. The technical solution of the present invention is:

[0047] A multi-component composite corrosion inhibitor for offshore CO2 flooding comprises: 8-10wt% of oleic acid imidazoline quaternary ammonium salt, 8-10wt% of oleic acid imidazoline lauric acid amide, 4-6wt% of potassium iodide, 4-6wt% of octylphenol polyoxyethylene ether, 4-6wt% of dodecyl dimethyl tertiary amine, 4-6wt% of auxiliary agent A, 4-6wt% of auxiliary agent B, and the rest is supplemented to 100wt% by anhydrous ethanol.

[0048] In the above-mentioned technical scheme, a quaternary ammonium cationic group is introduced, and its water solubility or water phase dispersibility is greatly improved. Quaternary ammonium salt itself is a strong electrolyte, which can maintain good solubility even under low pH conditions, and can be better mixed with the oil field water system, so as to more effectively reach the metal surface and play a corrosion inhibition role. The presence of the quaternary ammonium cationic group enhances its adsorption capacity on the metal surface, so that it can maintain a good corrosion inhibition effect in a wider pH range (including acidic, neutral and alkaline environments). The positive charge on the quaternary ammonium salt can form a stronger electrostatic attraction with the anion adsorption point on the metal surface to form a dense protective film. In addition, the hydrophilicity of the quaternary ammonium salt also helps the corrosion inhibitor to form a more stable hydration layer on the metal surface, thereby better isolating the corrosive medium. Usually a thicker, denser and more stable adsorption film can be formed, which can more effectively prevent the contact of the corrosive medium with the metal surface, thereby providing a more lasting protection.

[0049] Preferably, the auxiliary agent A is one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

[0050] The auxiliary agent B is one of sodium dodecylbenzene sulfonate, thiourea and fatty alcohol polyoxyethylene ether.

[0051] Preferably, the structural formula of the oleic acid imidazoline quaternary ammonium salt is as follows:

[0052]

[0053] The structural formula of the oleic acid imidazoline lauric acid amide is as follows:

[0054]

[0055] The preparation method of the above-mentioned multi-component compound corrosion inhibitor is:

[0056] After uniformly mixing oleic acid imidazoline quaternary ammonium salt, oleic acid imidazoline lauric acid amide and anhydrous ethanol at 45-55°C, potassium iodide was added and stirred until dissolved, and then auxiliary agent A was added and stirred until dissolved. The solution turned yellow to obtain a mixed solution 1;

[0057] Octylphenol polyoxyethylene ether is added to the mixed solution 1, stirred until dissolved, and then the additive B is added. After mixing evenly at 50-55° C., dodecyl dimethyl tertiary amine is added and mixed evenly to obtain the multi-component corrosion inhibitor.

[0058] Preferably, the preparation method of the oleic acid imidazoline quaternary ammonium salt is as follows: oleic acid imidazoline, benzyl chloride, and solvent xylene are stirred at 110-120° C. for 3-4 hours under a nitrogen atmosphere, and xylene is removed to obtain the oleic acid imidazoline quaternary ammonium salt;

[0059] The preparation method of the oleic acid imidazoline lauric acid amide is as follows: oleic acid imidazoline, lauric acid, and solvent xylene are stirred for reaction at 110-120° C. for 3-4 hours under a nitrogen atmosphere, and xylene is removed to obtain the oleic acid imidazoline lauric acid amide;

[0060] Further preferably, the preparation method of the oleic acid imidazoline is:

[0061] Solvent xylene, oleic acid and tetraethylenepentamine are refluxed for 4-5 hours at 140-150° C. under nitrogen protection, and the reflux reaction is terminated after the water generated by the reaction is separated; the reaction is then continued at 210-220° C. until the actual dehydration amount is more than 85% of the theoretical dehydration amount, and xylene is removed to obtain oleic acid imidazoline.

[0062] Further preferably, the molar ratio of oleic acid imidazoline to benzyl chloride is 1:1-1.2;

[0063] The molar ratio of oleic acid imidazoline to lauric acid is 1:1-1.2;

[0064] The molar ratio of oleic acid to tetraethylenepentamine is 1:1.2-1.4.

[0065] Further preferably, the molar ratio of oleic acid imidazoline to benzyl chloride is 1:1.1;

[0066] The molar ratio of oleic acid imidazoline to lauric acid is 1:1.1;

[0067] The molar ratio of oleic acid to tetraethylenepentamine is 1:1.3.

[0068] The application of the above-mentioned multi-component compound corrosion inhibitor in offshore CO2 oil recovery.

[0069] Preferably, the working temperature of the multi-component corrosion inhibitor is 90°C.

[0070] The technical scheme of the present invention adopts the composition of multi-component compounding, and oleic acid imidazoline quaternary ammonium salt or oleic acid imidazoline lauric acid amide itself can be adsorbed on the metal surface through polar groups to form a film, and the film has defects or weak links. However, the multi-component compounding system may contain some substances that can fill the defects or weak links of the film formed by oleic acid imidazoline quaternary ammonium salt or oleic acid imidazoline lauric acid amide. For example, some small molecular organic amines can enter the gap of oleic acid imidazoline lauric acid amide film, making the structure of the film more compact, and further improving the barrier ability of the film to corrosive media such as carbon dioxide and water. Embodiments of the present invention are as follows:

[0071] Example 1.

[0072] The corrosion inhibitor of this embodiment is composed of the following substances in percentage by weight: 8% of oleic acid imidazoline quaternary ammonium salt (named H), 9% of oleic acid imidazoline lauric acid amide (named Y), 4% of potassium iodide, 4% of octylphenol polyoxyethylene ether (OP-10), 5% of dodecyl dimethyl tertiary amine (MSDS), 5% of dodecyl trimethyl ammonium bromide (DTAB), 6% of sodium dodecylbenzene sulfonate (SDBS), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0073] The specific steps are as follows:

[0074] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0075] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0076] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 9.84 g (0.052 mol) of tetraethylene pentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 140°C, reflux the reaction at this temperature for 4 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 220°C and react for 5 hours, until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, and then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0077] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 110° C. After reaching the temperature, add 5.57 g (0.044 mol) of benzyl chloride, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0078] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 120°C. After reaching the temperature, add 8.81 g (0.044 mol) of lauric acid, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0079] The synthesized components H and Y were tested by infrared spectroscopy, and the results were as follows: Figure 4-5 shown.

[0080] The infrared spectrum of oleic acid imidazoline quaternary ammonium salt (H) is explained as follows:

[0081] exist Figure 4 In the spectrum, 2930cm -1The peak at 2854 cm is the asymmetric stretching vibration peak of -CH3. -1 The peak at 1455cm is the symmetrical stretching vibration peak of -CH2. -1 The peak at 1602 cm is the asymmetric stretching vibration peak of -CH2. -1 The peak at 1651 cm is the stretching vibration peak of the C=N bond of the imidazoline ring. -1 The characteristic absorption peak of the unsaturated C=C double bond in oleic acid is 1544 cm -1 The characteristic absorption peaks of NH single bond are at 1302 and 1086 cm -1 The CN stretching vibration peak is at . The structure of the synthetic product H can be determined by infrared spectroscopy.

[0082] The infrared spectrum of oleic acid imidazoline lauric acid amide (Y) is explained as follows:

[0083] exist Figure 5 In the spectrum, 2930cm -1 The peak at 2854 cm is the asymmetric stretching vibration peak of -CH3. -1 The peak at 1455cm is the symmetrical stretching vibration peak of -CH2. -1 The peak at 1602 cm is the asymmetric stretching vibration peak of -CH2. -1 The peak at 1651 cm is the stretching vibration peak of the C=N bond of the imidazoline ring. -1 The characteristic absorption peak of the unsaturated C=C double bond in oleic acid is 1630 cm -1 The characteristic peak of the C=O bond of the amide bond is 1544 cm -1 The peak at 1302 is the characteristic absorption peak of NH single bond. The peak at 1302 is the CN stretching vibration peak. The structure of the synthetic product Y can be determined by infrared spectroscopy.

[0084] B: Compounding process

[0085] The following steps are involved:

[0086] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 50°C and stir to dissolve evenly. Add the formulated amount of potassium iodide and stir until completely dissolved. Let stand for 15 minutes, then add the formulated amount of dodecyltrimethylammonium bromide (DTAB) and stir until completely dissolved. Let stand and cool for 15 minutes. The solution turns into a yellow liquid.

[0087] (2) Take the formulated amount of octylphenol polyoxyethylene ether (OP-10) and add it to the yellow liquid obtained in step (1), stir it and let it stand for 10 minutes, add the formulated amount of sodium dodecylbenzene sulfonate (SDBS), heat it to 50°C and stir it thoroughly, stir it and let it stand for 10 minutes.

[0088] (3) Add the formulated amount of dodecyl dimethyl tertiary amine (MSDS) in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0089] The purpose of standing still during the compounding process is to check whether the mixture is mixed evenly.

[0090] C: Test

[0091] The obtained composite corrosion inhibitor was added to a sealed device filled with a CO2 saturated corrosion solution at a concentration of 300 mg / L, and the temperature was kept at 90°C. The corrosion rate was tested using a weight loss coupon test method. The results showed that when 300 mg / L was added, the corrosion inhibition efficiency of the corrosion inhibitor prepared in Example 1 was 84.48%.

[0092] Example 2.

[0093] The corrosion inhibitor of this embodiment is composed of the following substances in weight percentage: 8% of oleic acid imidazoline quaternary ammonium salt (named H), 9% of oleic acid imidazoline lauric acid amide (named Y), 4% of potassium iodide, 4% of octylphenol polyoxyethylene ether (OP-10), 5% of dodecyl dimethyl tertiary amine (MSDS), 5% of dodecyl trimethyl ammonium bromide (DTAB), 6% of thiourea (TU), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0094] The specific steps are as follows:

[0095] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0096] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0097] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 9.84 g (0.052 mol) of tetraethylene pentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 140°C, reflux the reaction at this temperature for 4 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 220°C and react for 5 hours, until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, and then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0098] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 110° C. After reaching the temperature, add 5.57 g (0.044 mol) of benzyl chloride, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0099] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 120°C. After reaching the temperature, add 8.81 g (0.044 mol) of lauric acid, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0100] B: Compounding process

[0101] The following steps are involved:

[0102] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 50°C and stir to dissolve evenly. Add the formulated amount of potassium iodide and stir until completely dissolved. Let stand for 15 minutes, then add the formulated amount of dodecyltrimethylammonium bromide (DTAB) and stir until completely dissolved. Let stand and cool for 15 minutes. The solution turns into a yellow liquid.

[0103] (2) Add the formulated amount of thiourea (TU) to the yellow liquid obtained in step (1), stir and let stand for 10 min, add the formulated amount of sodium dodecylbenzene sulfonate (SDBS), heat to 50° C., stir thoroughly, stir and let stand for 10 min.

[0104] (3) Add the formulated amount of dodecyl dimethyl tertiary amine (MSDS) in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0105] Test: The obtained composite corrosion inhibitor was added to a sealed device filled with a CO2 saturated corrosion solution at a concentration of 300 mg / L, and the temperature was kept at 90°C. The corrosion rate was tested using a weight loss coupon test method. The results showed that when 300 mg / L was added, the corrosion inhibition efficiency of the corrosion inhibitor prepared in Example 2 was 90.67%.

[0106] Example 3.

[0107] The corrosion inhibitor of this embodiment is composed of the following substances in percentage by weight: 8% of oleic acid imidazoline quaternary ammonium salt (named H), 9% of oleic acid imidazoline lauric acid amide (named Y), 4% of potassium iodide, 4% of octylphenol polyoxyethylene ether (OP-10), 5% of dodecyl dimethyl tertiary amine (MSDS), 5% of tetradecyl trimethyl ammonium bromide (TTAB), 6% of sodium dodecyl benzene sulfonate (SDBS), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0108] The specific steps are as follows:

[0109] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0110] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0111] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 9.84 g (0.052 mol) of tetraethylene pentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 140°C, reflux the reaction at this temperature for 4 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 220°C and react for 5 hours, until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, and then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0112] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 110° C. After reaching the temperature, add 5.57 g (0.044 mol) of benzyl chloride, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0113] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 120°C. After reaching the temperature, add 8.81 g (0.044 mol) of lauric acid, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0114] B: Compounding process

[0115] The following steps are involved:

[0116] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 50°C and stir to dissolve evenly. Add the formulated amount of potassium iodide and stir until completely dissolved. Let stand for 15 minutes, then add the formulated amount of tetradecyltrimethylammonium bromide (TTAB) and stir until completely dissolved. Let stand and cool for 15 minutes, and the solution turns into a yellow liquid.

[0117] (2) Take the formulated amount of octylphenol polyoxyethylene ether (OP-10) and add it to the yellow liquid obtained in step (1), stir it and let it stand for 10 minutes, add the formulated amount of sodium dodecylbenzene sulfonate (SDBS), heat it to 50°C and stir it thoroughly, stir it and let it stand for 10 minutes.

[0118] (3) Add the formulated amount of dodecyl dimethyl tertiary amine (MSDS) in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0119] Test: The obtained composite corrosion inhibitor was added to a sealed device filled with a CO2 saturated corrosion solution at a concentration of 300 mg / L, and the temperature was kept at 90°C. The corrosion rate was tested using a weight loss coupon test method. The results showed that when 300 mg / L was added, the corrosion inhibition efficiency of the corrosion inhibitor prepared in Example 3 was 83.56%.

[0120] Example 4.

[0121] The corrosion inhibitor of this embodiment is composed of the following substances in percentage by weight: 8% of oleic acid imidazoline quaternary ammonium salt (named H), 9% of oleic acid imidazoline lauric acid amide (named Y), 4% of potassium iodide, 4% of octylphenol polyoxyethylene ether (OP-10), 4% of dodecyl dimethyl tertiary amine (MSDS), 5% of hexadecyl trimethyl ammonium bromide (CTAB), 6% of sodium dodecylbenzene sulfonate (SDBS), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0122] The specific steps are as follows:

[0123] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0124] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0125] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 9.84 g (0.052 mol) of tetraethylene pentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 140°C, reflux the reaction at this temperature for 4 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 220°C and react for 5 hours, until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, and then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0126] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 110° C. After reaching the temperature, add 5.57 g (0.044 mol) of benzyl chloride, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0127] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 120°C. After reaching the temperature, add 8.81 g (0.044 mol) of lauric acid, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0128] B: Compounding process

[0129] The following steps are involved:

[0130] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 50°C and stir to dissolve evenly. Add the formulated amount of potassium iodide and stir until completely dissolved. Let stand for 15 minutes, then add the formulated amount of hexadecyltrimethylammonium bromide (CTAB) and stir until completely dissolved. Let stand and cool for 15 minutes, and the solution turns into a yellow liquid.

[0131] (2) Take the formulated amount of octylphenol polyoxyethylene ether (OP-10) and add it to the yellow liquid obtained in step (1), stir it and let it stand for 10 minutes, add the formulated amount of sodium dodecylbenzene sulfonate (SDBS), heat it to 50°C and stir it thoroughly, stir it and let it stand for 10 minutes.

[0132] (3) Add the formulated amount of dodecyl dimethyl tertiary amine (MSDS) in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0133] Test: The obtained composite corrosion inhibitor was added to a sealed device filled with a CO2 saturated corrosion solution at a concentration of 300 mg / L, and the temperature was kept at 90°C. The corrosion rate was tested using a weight loss coupon test method. The results showed that when 300 mg / L was added, the corrosion inhibition efficiency of the corrosion inhibitor prepared in Example 4 was 89.30%.

[0134] Example 5.

[0135] The corrosion inhibitor of this embodiment is composed of the following substances in weight percentage: 8% of oleic acid imidazoline quaternary ammonium salt (named H), 9% of oleic acid imidazoline lauric acid amide (named Y), 4% of potassium iodide, 4% of octylphenol polyoxyethylene ether (OP-10), 5% of dodecyl dimethyl tertiary amine (MSDS), 5% of dodecyl trimethyl ammonium bromide (DTAB), 6% of fatty alcohol polyoxyethylene ether (AEO), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0136] The specific steps are as follows:

[0137] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0138] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0139] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 9.84 g (0.052 mol) of tetraethylene pentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 140°C, reflux the reaction at this temperature for 4 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 220°C and react for 4 hours until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0140] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 110° C. After reaching the temperature, add 5.57 g (0.044 mol) of benzyl chloride, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0141] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 120°C. After reaching the temperature, add 8.81 g (0.044 mol) of lauric acid, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0142] B: Compounding process

[0143] The following steps are involved:

[0144] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 50°C and stir to dissolve evenly. Add the formulated amount of potassium iodide and stir until completely dissolved. Let stand for 15 minutes, then add the formulated amount of dodecyltrimethylammonium bromide (DTAB) and stir until completely dissolved. Let stand and cool for 15 minutes. The solution turns into a yellow liquid.

[0145] (2) Take the formulated amount of octylphenol polyoxyethylene ether (OP-10) and add it to the yellow liquid obtained in step (1), stir it and let it stand for 10 minutes, add the formulated amount of fatty alcohol polyoxyethylene ether (AEO), heat it to 50°C and stir it thoroughly, stir it and let it stand for 10 minutes.

[0146] (3) Add the formulated amount of dodecyl dimethyl tertiary amine (MSDS) in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0147] Test: The obtained composite corrosion inhibitor was added to a sealed device filled with a CO2 saturated corrosion solution at a concentration of 300 mg / L, and the temperature was kept at 90°C. The corrosion rate was tested using a weight loss coupon test method. The results showed that when 300 mg / L was added, the corrosion inhibition efficiency of the corrosion inhibitor prepared in this embodiment was 84.73%.

[0148] Example 6

[0149] The corrosion inhibitor of this embodiment is composed of the following substances in percentage by weight: 8% of oleic acid imidazoline quaternary ammonium salt (named H), 9% of oleic acid imidazoline lauric acid amide (named Y), 4% of potassium iodide, 4% of octylphenol polyoxyethylene ether (OP-10), 5% of dodecyl dimethyl tertiary amine (MSDS), 5% of hexadecyl trimethyl ammonium bromide (CTAB), 6% of fatty alcohol polyoxyethylene ether (AEO), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0150] The specific steps are as follows:

[0151] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0152] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0153] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 9.84 g (0.052 mol) of tetraethylene pentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 140°C, reflux the reaction at this temperature for 4 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 220°C and react for 5 hours, until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, and then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0154] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 110° C. After reaching the temperature, add 5.57 g (0.044 mol) of benzyl chloride, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0155] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 120°C. After reaching the temperature, add 8.81 g (0.044 mol) of lauric acid, and stir and react at constant temperature for 4 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0156] B: Compounding process

[0157] The following steps are involved:

[0158] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 50°C and stir to dissolve evenly. Then add the formulated amount of potassium iodide and stir until it is completely dissolved. Let it stand for 15 minutes, then add the formulated amount of hexadecyltrimethylammonium bromide (CTAB) and stir until it is completely dissolved. Let it stand and cool for 15 minutes. The solution turns into a yellow liquid.

[0159] (2) Take the formulated amount of octylphenol polyoxyethylene ether (OP-10) and add it to the yellow liquid obtained in step (1), stir it and let it stand for 10 minutes, add the formulated amount of fatty alcohol polyoxyethylene ether (AEO), heat it to 50°C and stir it thoroughly, stir it and let it stand for 10 minutes.

[0160] (3) Add the formulated amount of dodecyl dimethyl tertiary amine (MSDS) in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0161] Test: The obtained composite corrosion inhibitor was added to a sealed device filled with a CO2 saturated corrosion solution at a concentration of 300 mg / L, and the temperature was kept at 90°C. The corrosion rate was tested using a weight loss coupon test method. The results showed that when 300 mg / L was added, the corrosion inhibition efficiency of the corrosion inhibitor prepared in Example 1 was 87.72%.

[0162] Example 7.

[0163] The corrosion inhibitor of this embodiment is composed of the following substances in weight percentage: 9% of oleic acid imidazoline quaternary ammonium salt (named H), 8% of oleic acid imidazoline lauric acid amide (named Y), 5% of potassium iodide, 5% of octylphenol polyoxyethylene ether (OP-10), 5% of dodecyl dimethyl tertiary amine (MSDS), 4% of hexadecyl trimethyl ammonium bromide (CTAB), 4% of fatty alcohol polyoxyethylene ether (AEO), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0164] The specific steps are as follows:

[0165] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0166] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0167] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 9.08 g (0.048 mol) of tetraethylenepentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 150°C, reflux the reaction at this temperature for 5 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 210°C and react for 4.5 hours until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0168] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 120° C. After reaching the temperature, add 5.06 g (0.04 mol) of benzyl chloride, and stir and react at the constant temperature for 3 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0169] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 110°C. After reaching the temperature, add 8.01 g (0.04 mol) of lauric acid, and stir and react at constant temperature for 3.5 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0170] B: Compounding process

[0171] The following steps are involved:

[0172] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 45°C and stir to dissolve evenly. Then add the formulated amount of potassium iodide and stir until it is completely dissolved. Let it stand for 15 minutes, then add the formulated amount of hexadecyltrimethylammonium bromide (CTAB) and stir until it is completely dissolved. Let it stand and cool for 15 minutes. The solution turns into a yellow liquid.

[0173] (2) Take the formulated amount of octylphenol polyoxyethylene ether (OP-10) and add it to the yellow liquid obtained in step (1), stir it and let it stand for 10 minutes, add the formulated amount of fatty alcohol polyoxyethylene ether (AEO), heat it to 52° C. and stir it thoroughly, stir it and let it stand for 10 minutes.

[0174] (3) Add the formulated amount of dodecyl dimethyl tertiary amine (MSDS) in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0175] Example 8.

[0176] The corrosion inhibitor of this embodiment is composed of the following substances in weight percentage: 10% of oleic acid imidazoline quaternary ammonium salt (named H), 10% of oleic acid imidazoline lauric acid amide (named Y), 6% of potassium iodide, 6% of octylphenol polyoxyethylene ether (OP-10), 6% of dodecyl dimethyl tertiary amine (MSDS), 6% of hexadecyl trimethyl ammonium bromide (CTAB), 5% of fatty alcohol polyoxyethylene ether (AEO), and the rest is supplemented to 100% by solvent, and the solvent is anhydrous ethanol.

[0177] The specific steps are as follows:

[0178] A: Synthesis of H and Y (see the synthesis flow chart) Figure 1 and Figure 2 )

[0179] H and Y are prepared by reacting oleic acid, tetraethylenepentamine, benzyl chloride or lauric acid in xylene. The specific steps are as follows:

[0180] (1) Add 25 mL of xylene, 11.3 g (0.04 mol) of oleic acid and 10.60 g (0.056 mol) of tetraethylenepentamine to a 100 mL three-necked flask with a water separator and a condenser, and use nitrogen as the protective gas. Set the heating program, and after the temperature of the heating jacket reaches 145°C, reflux the reaction at this temperature for 4.5 hours, and separate the water generated by the reaction through the water separator. After the reflux reaction is completed, heat it to 215°C and react for 4 hours until the actual dehydration amount reaches more than 85% of the theoretical dehydration amount, then stop the reaction. Remove the xylene by rotary evaporation to obtain oleic acid imidazoline.

[0181] (2) Stir the oleic acid imidazoline (0.04 mol) obtained in the above step (1) under nitrogen protection, and heat it to 115° C. After reaching the temperature, add 6.08 g (0.048 mol) of benzyl chloride, and stir and react at constant temperature for 3.5 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline quaternary ammonium salt, i.e., component H.

[0182] (3) Repeat step (1), stir the obtained oleic acid imidazoline (0.04 mol) under nitrogen protection, and heat to 115°C. After reaching the temperature, add 9.61 g (0.048 mol) of lauric acid, and stir and react at constant temperature for 3 hours. Remove xylene by rotary evaporation to obtain oleic acid imidazoline lauric acid amide, i.e., component Y.

[0183] B: Compounding process

[0184] The following steps are involved:

[0185] (1) Take the formulated amount of component H, component Y, and solvent and add them to a beaker, heat to 55°C and stir to dissolve evenly. Then add the formulated amount of potassium iodide and stir until it is completely dissolved. Let it stand for 15 minutes, then add the formulated amount of hexadecyltrimethylammonium bromide (CTAB) and stir until it is completely dissolved. Let it stand and cool for 15 minutes. The solution turns into a yellow liquid.

[0186] (2) Take the formulated amount of octylphenol polyoxyethylene ether (OP-10) and add it to the yellow liquid obtained in step (1), stir it and let it stand for 10 minutes, add the formulated amount of fatty alcohol polyoxyethylene ether (AEO), heat it to 55°C and stir it thoroughly, stir it and let it stand for 10 minutes.

[0187] (3) Add the formulated amount of MSDS in sequence and stir evenly to obtain a multi-component compound CO2 corrosion inhibitor.

[0188] Example 9.

[0189] (1) The corrosion inhibition performance of the multi-component compounded CO2 corrosion inhibitor prepared in Examples 1-6 was tested.

[0190] Method: It was used in the corrosion weight loss experiment of Q235 carbon steel in 3.5wt% NaCl solution containing CO2. 3.5wt% NaCl solution is to simulate the produced water of offshore high-salinity oilfield. The size of Q235 coupon is 50x25x2mm, the corrosion temperature is 90℃, and the standard adopted is "SY-T 5273-2014 Performance Indicators and Evaluation Methods of Corrosion Inhibitors for Oilfield Produced Water Treatment".

[0191] The corrosion inhibition performance test data are shown in Table 1, and the corrosion morphology is shown in Figure 1 shown.

[0192] Table 1 Corrosion inhibition performance test in 90℃ saturated CO2, 3.5wt%NaCl oilfield produced water corrosion solution

[0193]

[0194] From Table 1, we can conclude that the corrosion inhibition performance of the multi-component compound CO2 corrosion inhibitor is good and stable at high temperatures, which overcomes the shortcomings of existing offshore oil well corrosion inhibitors and can be used as a corrosion inhibitor for offshore oil wells.

[0195] Figure 1 The SEM corrosion morphology of a 90°C iron sheet corroded in a saturated CO2, 3.5wt% NaCl corrosion environment for 22 hours. As can be seen from the figure, the multi-component compound CO2 corrosion inhibitor prepared by the present invention can play a corrosion inhibition effect, and the performance of Example 2 is the best.

[0196] (2) Components H and Y

[0197] Comparative Examples 1-3 were set up for comparison with Example 2, and the test method in (1) was adopted.

[0198] Comparative Example 1: The specific implementation steps are the same as those in Example 2, except that H is not added during the compounding process.

[0199] Comparative Example 2: The specific implementation steps are the same as those in Example 2, except that Y is not added during the compounding process.

[0200] Comparative Example 3: The specific implementation process is the same as that of Example 2, except that neither H nor Y is added during the compounding process.

[0201] The results of the comparative implementation case of the corrosion inhibition performance test in 90°C saturated CO2 and 3.5wt% NaCl oilfield produced water corrosion solution are shown in Table 2.

[0202] Table 2

[0203]

[0204] From the corrosion inhibition rate results of the corrosion inhibitor in Table 2, it can be seen that H and Y play a major corrosion inhibition role in the multi-component compound CO2 corrosion inhibitor prepared by the present invention and are the main corrosion inhibitor components.

[0205] The above is only a preferred embodiment of the embodiment of the present invention, and does not impose any form of limitation on the embodiment of the present invention. Any simple modification, equivalent changes and modifications made to the above embodiment based on the technical essence of the embodiment of the present invention are still within the scope of the technical solution of the embodiment of the present invention.

Claims

1. A multi-component corrosion inhibitor for offshore CO2 flooding, characterized in that: include: Oleic acid imidazoline quaternary ammonium salt 8-10wt%, oleic acid imidazoline lauric acid amide 8-10wt%, potassium iodide 4-6wt%, octylphenol polyoxyethylene ether 4-6wt%, dodecyl dimethyl tertiary amine 4-6wt%, auxiliary agent A 4-6wt%, auxiliary agent B 4-6wt%, and the rest is supplemented by anhydrous ethanol to 100wt%.

2. The multi-component composite corrosion inhibitor according to claim 1, characterized in that: The auxiliary agent A is one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide. The auxiliary agent B is one of sodium dodecylbenzene sulfonate, thiourea and fatty alcohol polyoxyethylene ether.

3. The multi-component composite corrosion inhibitor according to claim 1, characterized in that: The structural formula of the oleic acid imidazoline quaternary ammonium salt is as follows: The structural formula of the oleic acid imidazoline lauric acid amide is as follows:

4. The method for preparing the multi-component composite corrosion inhibitor according to any one of claims 1 to 3, characterized in that: The preparation method is: After uniformly mixing oleic acid imidazoline quaternary ammonium salt, oleic acid imidazoline lauric acid amide and anhydrous ethanol at 45-55°C, potassium iodide was added and stirred until dissolved, and then auxiliary agent A was added and stirred until dissolved. The solution turned yellow to obtain a mixed solution 1; Octylphenol polyoxyethylene ether is added to the mixed solution 1, stirred until dissolved, and then the additive B is added. After mixing evenly at 50-55° C., dodecyl dimethyl tertiary amine is added and mixed evenly to obtain the multi-component corrosion inhibitor.

5. The preparation method according to claim 4, characterized in that: The preparation method of the oleic acid imidazoline quaternary ammonium salt is as follows: oleic acid imidazoline, benzyl chloride, and solvent xylene are stirred and reacted at 110-120° C. for 3-4 hours in a nitrogen atmosphere, and xylene is removed to obtain the oleic acid imidazoline quaternary ammonium salt; The preparation method of the oleic acid imidazoline lauric acid amide is as follows: oleic acid imidazoline, lauric acid and solvent xylene are stirred and reacted for 3-4 hours at 110-120° C. in a nitrogen atmosphere, and xylene is removed to obtain the oleic acid imidazoline lauric acid amide.

6. The preparation method according to claim 5, characterized in that: The preparation method of the oleic acid imidazoline is: Oleic acid, tetraethylenepentamine and solvent xylene are refluxed at 140-150°C for 4-5 hours under nitrogen protection, and the water generated by the reaction is separated, and the reflux reaction is terminated; then the reaction is continued at 210-220°C for 4-5 hours until the actual dehydration amount is more than 85% of the theoretical dehydration amount, and the xylene is removed to obtain oleic acid imidazoline.

7. The preparation method according to claim 6, characterized in that: The molar ratio of oleic acid imidazoline to benzyl chloride is 1:1-1.2; The molar ratio of oleic acid imidazoline to lauric acid is 1:1-1.2; The molar ratio of oleic acid to tetraethylenepentamine is 1:1.2-1.

4.

8. The preparation method according to claim 7, characterized in that: The molar ratio of oleic acid imidazoline to benzyl chloride is 1:1.1; The molar ratio of oleic acid imidazoline to lauric acid is 1:1.1; The molar ratio of oleic acid to tetraethylenepentamine is 1:1.

3.

9. Use of the multi-component composite corrosion inhibitor according to any one of claims 1 to 3, or the multi-component composite corrosion inhibitor prepared by the preparation method according to any one of claims 4 to 9 in offshore CO2 flooding.

10. The use according to claim 7, characterized in that: The working temperature of the multi-component composite corrosion inhibitor is 90°C.

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