An oilfield water treatment corrosion inhibitor and a method for synthesizing the same

Abstract

The application belongs to the technical field of sewage treatment and specifically relates to an oilfield water treatment corrosion inhibitor and a synthesis method thereof. The synthesis method comprises the following steps: in the presence of a reducing agent, 2-acetyl-2-thiazoline and N,N-dimethylaminopropylamine are subjected to a reductive amination reaction in a weak acid solvent; and then, in a weak alkaline environment, the reductive amination product is subjected to a tertiary amination reaction with chloroacetic acid. Based on 1 mol of 2-acetyl-2-thiazoline, the N,N-dimethylaminopropylamine and the chloroacetic acid are 0.9-1.1 mol and 0.9-1.3 mol, respectively. The application has the advantages of simple synthesis process, small dosage and good corrosion inhibition effect, and when the concentration is 10 mg / L, the corrosion inhibition rate reaches more than 97%.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and particularly relates to an oilfield water treatment corrosion inhibitor and a synthesis method thereof. Background Art

[0002] Most oilfields in my country are in the middle and late stages of waterflooding development, making oilfield wastewater treatment and reinjection water quality crucial. Corrosion is one of the most serious issues encountered during oilfield wastewater treatment and reinjection. Oilfield oily wastewater, due to its complex water quality, high levels of harmful components, and high mineralization, contains dissolved salts, H2S, CO2, sulfate-reducing bacteria, and dissolved oxygen. When reinjected into the formation, it can cause severe corrosion to metal equipment and piping in the waterflooding system. The addition of corrosion inhibitors can effectively mitigate this problem.

[0003] Commonly used corrosion inhibitors in oil fields include amines, cyclic amines, amides, amide carboxylic acids and their derivatives, imidazolines and their derivatives, etc. Currently, there are a wide variety of corrosion inhibitors both domestically and internationally, but they generally have disadvantages such as large dosages, low corrosion inhibition efficiency, and significant side effects.

[0004] CN108018559B discloses a compounded oilfield corrosion inhibitor and its preparation method, comprising liquid A and liquid B in a volume ratio of 1:3, wherein the active ingredient of liquid A is mainly an aromatic ketone Mannich base, and the active ingredient of liquid B is mainly oleic acid imidazoline. By compounding liquid A and liquid B, a high-temperature, oxygen-resistant, and acid-resistant downhole corrosion inhibitor is prepared through the synergistic effect of the two. However, the preparation process of this corrosion inhibitor requires a wide variety of drugs, the product is highly toxic, the preparation time is long, and high-temperature and strong acid and alkali resistant equipment such as reactors are required, which increases operating costs. At the same time, the corrosion inhibition efficiency is only 80%.

[0005] CN107760290B discloses a bactericidal corrosion inhibitor for oilfield water treatment systems, and its preparation and application methods. This invention has both bactericidal and corrosion-inhibiting properties, is highly effective in killing sulfate-reducing bacteria (SRB) and saprophytic bacteria (TGB), has a long-lasting efficacy, and has a simple production process and low cost. However, it can only inhibit CO2 corrosion of metals, and the metal is carbon steel, so the corrosion inhibition effect has limitations.

[0006] CN104817193B discloses a water treatment corrosion inhibitor and a preparation method thereof. The water treatment corrosion inhibitor is an imidazoline quaternary ammonium salt. The method comprises allowing an imidazoline compound and a quaternizing agent to undergo a salt-forming reaction to generate the imidazoline quaternary ammonium salt. The imidazoline compound is synthesized by reacting an organic carboxylic acid with an organic polyether polyamine. The quaternizing agent is a combination of one or more of dimethyl carbonate, diethyl carbonate, and ethylene carbonate. This method has low toxicity during the synthesis process and is simple to operate. However, to maintain excellent sustained-release ability, a higher dosage of the agent (5 g / L) is required, and the sustained-release rate is only about 5% higher than that of the corrosion inhibitor model OED. Summary of the Invention

[0007] The present invention addresses the shortcomings of the above-mentioned prior art and provides a water treatment corrosion inhibitor and a synthesis method thereof. The present invention has the advantages of a simple synthesis process, small dosage, and good corrosion inhibition effect. At a concentration of 10 mg / L, the corrosion rate is less than 0.0085 mm / a and the corrosion inhibition rate is greater than 97%.

[0008] Therefore, in order to achieve the above-mentioned purpose, on the one hand, the present invention discloses a corrosion inhibitor for oilfield water treatment, wherein the molecular structure of the corrosion inhibitor is as follows:

[0009]

[0010] On the other hand, the present invention provides a method for synthesizing an oilfield water treatment corrosion inhibitor, the method comprising: subjecting 2-acetyl-2-thiazoline and N,N-dimethylaminopropylamine to a reductive amination reaction in a weakly acidic solvent in the presence of a reducing agent; and secondly, subjecting the reductive amination product to a tertiary amination reaction with chloroacetic acid in a weakly alkaline environment.

[0011] The third object of the present invention is to disclose the application of the above corrosion inhibitor in oilfield wastewater treatment.

[0012] The oilfield water treatment corrosion inhibitor of the present invention comprises thiazoline, a tertiary amine base, and a carboxylic acid as functional groups. Its mechanism of action includes the following: multiple adsorption centers in the corrosion inhibitor molecule, such as N, O, and S, can provide lone pairs of electrons, improving the metal's oxidation resistance; the nitrogen in the thiazoline and the nitrogen in the tertiary amine can be adsorbed on the metal surface through various pathways, including electrostatic adsorption and the formation of coordinate bonds, forming a protective film that prevents contact between the metal and the liquid; the corrosion inhibitor molecules can also adhere to the metal surface, increasing the metal's resistance and reducing the occurrence of electrochemical corrosion.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] (1) The raw materials of the oilfield water treatment corrosion inhibitor of the present invention are cheap, easy to obtain, widely available, and have a simple synthesis process;

[0015] (2) The oilfield water treatment corrosion inhibitor of the present invention does not contain phosphorus in its molecules, is environmentally friendly, and does not produce secondary pollution;

[0016] (3) The oilfield water treatment corrosion inhibitor of the present invention has the advantages of small dosage and good corrosion inhibition effect. When the usage concentration is 10 mg / L, the corrosion inhibition rate is greater than 97.5% and the corrosion rate is less than 0.0085 mm / a. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attachment Figure 1 This is a real picture of the hanging piece at an oilfield joint station after 10 days of water corrosion. DETAILED DESCRIPTION

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] According to a first aspect of the present invention, the present invention discloses an oilfield water treatment corrosion inhibitor, the molecular structure of the oilfield water treatment corrosion inhibitor is as follows:

[0020]

[0021] In a second aspect, the present invention provides a method for synthesizing an oilfield water treatment corrosion inhibitor, the method comprising: subjecting 2-acetyl-2-thiazoline and N,N-dimethylaminopropylamine to a reductive amination reaction in a weakly acidic solvent in the presence of a reducing agent; and secondly, subjecting the reductive amination product to a tertiary amination reaction with chloroacetic acid in a weakly alkaline environment.

[0022] In the present invention, preferably, based on 1 mole of 2-acetyl-2-thiazoline, the N,N-dimethylaminopropylamine and chloroacetic acid are 0.9-1.1 mole parts and 0.9-1.3 mole parts, respectively; more preferably, based on 1 mole of 2-acetyl-2-thiazoline, the N,N-dimethylaminopropylamine and chloroacetic acid are 0.95-1.05 mole parts and 1-1.2 mole parts, respectively; even more preferably, based on 1 mole of 2-acetyl-2-thiazoline, the N,N-dimethylaminopropylamine and chloroacetic acid are 0.95-1.0 mole parts and 1-1.1 mole parts, respectively.

[0023] In the present invention, preferably, the reducing agent is one of sodium triacetoxyborohydride, sodium cyanoborohydride, sodium borohydride, and lithium borohydride, and the mass ratio of the reducing agent to 2-acetyl-2-thiazoline is 1-3:1.

[0024] More preferably, the reducing agent is sodium triacetoxyborohydride or sodium cyanoborohydride.

[0025] In the present invention, preferably, the weak acidity is pH 3-5.

[0026] More preferably, the weak acidity is pH 3-4.

[0027] In the present invention, preferably, the weakly acidic solvent is one of methanol, ethanol, propanol, isopropanol, and isobutanol, and the mass ratio of the weakly acidic solvent to 2-acetyl-2-thiazoline is 8-12:1.

[0028] More preferably, the weakly acidic solvent is one of methanol, ethanol and propanol.

[0029] In the present invention, preferably, the reductive amination reaction temperature is 50-60° C., and the reaction time is 0.5-2 h.

[0030] More preferably, the reductive amination reaction temperature is 50-55° C., and the reaction time is 0.5-1 h.

[0031] In the present invention, preferably, the weak alkalinity is pH 8-10.

[0032] More preferably, the weak alkalinity is pH 8-9.

[0033] In the present invention, preferably, the tertiary amination reaction temperature is 60-70° C., and the reaction time is 1-4 h.

[0034] More preferably, the tertiary amination reaction temperature is 60-65° C., and the reaction time is 1-3 h.

[0035] According to a more specific preferred embodiment, the synthesis method of the oilfield water treatment corrosion inhibitor specifically comprises the following steps:

[0036] (1) Add 2-acetyl-2-thiazoline, N,N-dimethylaminopropylamine, a reducing agent, and a solvent to a four-necked flask, adjust the pH to 3-4 with hydrochloric acid, heat to 50-60°C, and keep warm for a reductive amination reaction;

[0037] (2) adding chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 8-9 with a 2 mol / L sodium hydroxide solution, and keeping the mixture at 60-70° C., maintaining the pH at 8-9, to obtain a crude corrosion inhibitor solution;

[0038] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. Distilled water was added and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals. The crystals were dried at 80-85°C overnight to obtain a light yellow solid product.

[0039] Preferably, the mass ratio of distilled water to 2-acetyl-2-thiazoline is 6-8:1.

[0040] The reaction equation for the synthesis of the oilfield water treatment corrosion inhibitor of the present invention is as follows:

[0041]

[0042] The third object of the present invention is to disclose the application of the above-mentioned corrosion inhibitor in oilfield wastewater treatment. There are no special requirements for the specific application, and the conventional application method in the field can be used, which will not be discussed in detail here.

[0043] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0044] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0045] The present invention will be further described below with reference to specific embodiments.

[0046] In the present invention, the devices or equipment used are all conventional devices or equipment known in the art and are commercially available.

[0047] In the following examples and comparative examples, unless otherwise specified, all reagents used were commercially available chemically pure reagents.

[0048] Example 1

[0049] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.18 mol of N,N-dimethylaminopropylamine, 41.3 g of sodium triacetoxyborohydride, and 260 g of methanol to a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 58°C, and keep the temperature to allow the reductive amination reaction to proceed for 1.5 h.

[0050] (2) Add 0.18 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 8 with 2 mol / L sodium hydroxide solution, and keep the reaction at 60°C for 2 hours, maintaining the pH at 8, to obtain a crude corrosion inhibitor solution;

[0051] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 155 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals. The crystals were dried at 80°C overnight to obtain a light yellow solid corrosion inhibitor product N1.

[0052] Example 2

[0053] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.22 mol of N,N-dimethylaminopropylamine, 77.4 g of lithium borohydride, and 280 g of methanol to a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 57°C, and keep the temperature to allow for reductive amination reaction for 0.5 h;

[0054] (2) Add 0.26 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 9 with 2 mol / L sodium hydroxide solution, and keep the reaction at 70°C for 3 hours, maintaining the pH at 9, to obtain a crude corrosion inhibitor solution;

[0055] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 166 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals. The crystals were dried at 85°C overnight to obtain a light yellow solid corrosion inhibitor product N2.

[0056] Example 3

[0057] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.185 mol of N,N-dimethylaminopropylamine, 45.2 g of sodium borohydride, and 206.5 g of butanol to a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 56°C, and keep warm for 1 hour for reductive amination reaction;

[0058] (2) Add 0.19 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 9 with 2 mol / L sodium hydroxide solution, and keep the reaction at 60°C for 1 hour, maintaining the pH at 9, to obtain a crude corrosion inhibitor solution;

[0059] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 168 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered, and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals, which were then dried at 82°C overnight to obtain a light yellow solid corrosion inhibitor product N3.

[0060] Example 4

[0061] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.215 mol of N,N-dimethylaminopropylamine, 66.2 g of sodium cyanoborohydride, and 244 g of butanol to a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 53°C, and keep the temperature to allow the reductive amination reaction to proceed for 1.5 h.

[0062] (2) Add 0.25 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 8 with 2 mol / L sodium hydroxide solution, and keep the reaction at 62°C for 4 hours, maintaining the pH at 8, to obtain a crude corrosion inhibitor solution;

[0063] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 173 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered, and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals, which were then dried at 83°C overnight to obtain a light yellow solid corrosion inhibitor product N4.

[0064] Example 5

[0065] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.19 mol of N,N-dimethylaminopropylamine, 25.8 g of sodium triacetoxyborohydride, and 268 g of propanol to a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 52°C, and keep the temperature to allow the reductive amination reaction to proceed for 1.5 h.

[0066] (2) Add 0.2 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 9 with 2 mol / L sodium hydroxide solution, and keep the reaction at 63°C for 2 hours, maintaining the pH at 9, to obtain a crude corrosion inhibitor solution;

[0067] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 188 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered, and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals, which were then dried at 85°C overnight to obtain a light yellow solid corrosion inhibitor product N5.

[0068] Example 6

[0069] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.21 mol of N,N-dimethylaminopropylamine, 40.2 g of sodium borohydride, and 285 g of propanol to a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 55°C, and keep warm for 2 h for reductive amination reaction;

[0070] (2) Add 0.24 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 8 with 2 mol / L sodium hydroxide solution, and keep the reaction at 65°C for 3 hours, maintaining the pH at 8, to obtain a crude corrosion inhibitor solution;

[0071] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 180 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered, and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals, which were then dried at 85°C overnight to obtain a light yellow solid corrosion inhibitor product N6.

[0072] Example 7

[0073] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.195 mol of N,N-dimethylaminopropylamine, 60.3 g of sodium triacetoxyborohydride, and 309 g of ethanol to a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 55°C, and keep the temperature to allow for reductive amination reaction for 2 h;

[0074] (2) Add 0.21 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 9 with 2 mol / L sodium hydroxide solution, and keep the reaction at 67°C for 2 hours, maintaining the pH at 9, to obtain a crude corrosion inhibitor solution;

[0075] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 195 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered, and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals, which were then dried at 82°C overnight to obtain a light yellow solid corrosion inhibitor product N7.

[0076] Example 8

[0077] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.205 mol of N,N-dimethylaminopropylamine, 51.2 g of sodium cyanoborohydride, and 300 g of isopropanol to a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 60°C, and keep the temperature to allow the reductive amination reaction to proceed for 1.5 h.

[0078] (2) Add 0.23 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 9 with 2 mol / L sodium hydroxide solution, and keep the reaction at 68°C for 2 hours, maintaining the pH at 9, to obtain a crude corrosion inhibitor solution;

[0079] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 200 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered, and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals. The solution was dried at 82°C overnight to obtain a light yellow solid corrosion inhibitor product N8.

[0080] Example 9

[0081] (1) Add 0.2 mol of 2-acetyl-2-thiazoline, 0.2 mol of N,N-dimethylaminopropylamine, 48.6 g of lithium borohydride, and 309 g of isopropanol to a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 50°C, and keep the temperature to allow the reductive amination reaction to proceed for 1.5 h.

[0082] (2) Add 0.22 mol of chloroacetic acid to the above reductive amination reaction mixture, adjust the pH to 9 with 2 mol / L sodium hydroxide solution, and keep the reaction at 70°C for 2 hours, maintaining the pH at 9, to obtain a crude corrosion inhibitor solution;

[0083] (3) The crude corrosion inhibitor solution was distilled under reduced pressure to 80°C until no distillate was produced. 206 g of distilled water was added, and the pH was adjusted to 9-10 with sodium hydroxide. The solution was filtered and the pH of the filtrate was adjusted to 3-4. The solution was cooled with ice water to below 5°C to precipitate crystals. The crystals were dried at 83°C overnight to obtain a light yellow solid corrosion inhibitor product N9.

[0084] Example 10 Laboratory Corrosion Inhibitor Evaluation

[0085] The corrosion inhibitors N1-N9 of the present invention were tested and evaluated in the laboratory. The evaluation method was based on GB / T 18175-2014 "Determination of Corrosion Inhibition Performance of Water Treatment Agents". The test water was concentrated water from a chemical plant boiler. Ethylenediaminetetramethylenephosphonic acid (EDTMP) was used for comparison at dosing concentrations of 5 and 10 mg / L. The evaluation results are shown in Table 1.

[0086] Table 1 Boiler water corrosion test results

[0087]

[0088] From Table 1 we can see that:

[0089] (1) When the corrosion inhibitors N1-N9 of the present invention are used at a concentration of 5 mg / L, the corrosion rates are all less than 0.012 mm / a, among which the corrosion rate of N9 is the lowest, reaching 0.0069 mm / a, while the corrosion rate of ethylenediaminetetramethylenephosphonic acid (EDTMP) in comparative example 1 is 0.0283 mm / a, which is significantly higher than that of the present invention; when the corrosion concentration is 10 mg / L, the corrosion rates are all less than 0.0085 mm / a, among which the corrosion rate of N9 is the lowest, reaching 0.0043 mm / a, while the corrosion rate of ethylenediaminetetramethylenephosphonic acid (EDTMP) in comparative example 1 is 0.0233 mm / a, which is significantly higher than that of the present invention.

[0090] (2) When the corrosion inhibitors N1-N9 of the present invention are used at a concentration of 5 mg / L, the corrosion inhibition rates are all greater than 97%, among which the corrosion inhibition rate of N9 is the highest, reaching 98.7%, while the corrosion inhibition rate of ethylenediaminetetramethylenephosphonic acid (EDTMP) in comparative example 1 is 93.9%, which is significantly lower than that of the present invention; when the corrosion inhibition concentration is 10 mg / L, the corrosion inhibition rates are all greater than 97.9%, among which the corrosion inhibition rate of N9 is the highest, reaching 99.3%, while the corrosion inhibition rate of ethylenediaminetetramethylenephosphonic acid (EDTMP) in comparative example 1 is 95.2%, which is significantly lower than that of the present invention.

[0091] Example 11 Corrosion Inhibitor Evaluation

[0092] Take 4L of water from a joint oilfield station, set up four control experiments, set up two blank groups K1 and K2, and two experimental groups H1 and H2, add 10mg / L of N8 and N9 of the present invention to each, put them in a 60℃ oven, and take them out after 10 days. The results are shown in the figure. Figure 1 , the test results are shown in Table 2.

[0093] Table 2 Water corrosion test results of the joint station

[0094] corrosion inhibitors Corrosion rate, mm / a <![CDATA[K1]]> 0.478 <![CDATA[K2]]> 0.436 <![CDATA[H1]]> 0.0068 <![CDATA[H2]]> 0.0072

[0095] From Table 2, we can conclude that:

[0096] The average water corrosion rate of the joint station is (0.478+0.436) / 2=0.457 (mm / a).

[0097] The corrosion inhibition rate of N8 is (0.457-0.0068) / 0.457×100%=98.5%.

[0098] The corrosion inhibition rate of N9 is (0.457-0.0072) / 0.457×100%=98.4%.

[0099] The corrosion inhibitors N8 and N9 of the present invention have good effects in field tests, with a corrosion inhibition rate of more than 98%.

[0100] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A corrosion inhibitor for oilfield water treatment, characterized in that: The molecular structural formula of the oilfield water treatment corrosion inhibitor is as follows:

2. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 1, wherein: The synthesis method comprises: in the presence of a reducing agent, allowing 2-acetyl-2-thiazoline and N,N-dimethylaminopropylamine to undergo a reductive amination reaction in a weakly acidic solvent; and secondly, allowing the reductive amination product to undergo a tertiary amination reaction with chloroacetic acid in a weakly alkaline environment.

3. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 2, wherein: Based on 1 mol part of 2-acetyl-2-thiazoline, the N,N-dimethylaminopropylamine and chloroacetic acid are 0.9-1.1 mol parts and 0.9-1.3 mol parts respectively.

4. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 3, characterized in that: Based on 1 mole of 2-acetyl-2-thiazoline, the amounts of N,N-dimethylaminopropylamine and chloroacetic acid are 0.95-1.05 mole parts and 1-1.2 mole parts, respectively.

5. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 4, characterized in that: Based on 1 mole of 2-acetyl-2-thiazoline, the amounts of N,N-dimethylaminopropylamine and chloroacetic acid are 0.95-1.0 mole and 1-1.1 mole, respectively.

6. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 2, wherein: The reducing agent is one of sodium triacetoxyborohydride, sodium cyanoborohydride, sodium borohydride and lithium borohydride, and the mass ratio of the reducing agent to 2-acetyl-2-thiazoline is 1-3:

1.

7. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 6, characterized in that: The reducing agent is sodium triacetoxyborohydride or sodium cyanoborohydride.

8. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 2, wherein: The weak acid solvent is one of methanol, ethanol, propanol, isopropanol and isobutanol, and the mass ratio of the weak acid solvent to 2-acetyl-2-thiazoline is 8-12:

1.

9. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 8, characterized in that: The weakly acidic solvent is one of methanol, ethanol and propanol.

10. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 2, characterized in that: The weak acidity is pH 3-5.

11. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 10, characterized in that: The weak acidity is pH 3-4.

12. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 2, characterized in that: The reductive amination reaction temperature is 50-60° C., and the reaction time is 0.5-2 h.

13. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 12, characterized in that: The reductive amination reaction temperature is 50-55° C., and the reaction time is 0.5-1 h.

14. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 2, characterized in that: The weak alkalinity is pH 8-10.

15. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 14, characterized in that: The weak alkalinity is pH 8-9.

16. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 2, characterized in that: The tertiary amination reaction temperature is 60-70° C., and the reaction time is 1-4 hours.

17. The method for synthesizing an oilfield water treatment corrosion inhibitor according to claim 16, characterized in that: The tertiary amination reaction temperature is 60-65° C., and the reaction time is 1-3 hours.

18. Use of the oilfield water treatment corrosion inhibitor according to claim 1 in oilfield wastewater treatment.

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