Oil field water treatment corrosion inhibitor and synthesis method thereof

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to an oil field water treatment corrosion inhibitor and a synthesis method thereof. The synthesis method comprises the following steps: in the presence of a reducing agent, carrying out reductive amination reaction on 2-acetyl-2-thiazoline and N, N-dimethylaminopropylamine in a weakly acidic solvent; secondly, in a weakly alkaline environment, the reductive amination product and chloroacetic acid are subjected to a tertiary amination reaction; on the basis of 1 mole part of 2-acetyl-2-thiazoline, the N, N-dimethylaminopropylamine accounts for 0.9 to 1.1 mole parts, and the chloroacetic acid accounts for 0.9 to 1.3 mole parts, respectively. The corrosion inhibitor has the advantages of simple synthesis process, small dosage and good corrosion inhibition effect, and when the use concentration is 10mg / L, the corrosion inhibition rate reaches 97% or above.

Description

Technical Field

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

[0002] Most of my country's oil fields are in the middle and late stages of water injection development. Oilfield wastewater treatment and reinjection water quality are very important. Corrosion is one of the most serious problems encountered in the process of oilfield wastewater treatment and reinjection. Oilfield oily wastewater has complex water quality, high harmful components, high mineralization, and contains dissolved salts, H 2 S, CO 2 , sulfate-reducing bacteria, dissolved oxygen, etc., will cause serious corrosion to the metal equipment and pipelines in the water injection system after being reinjected into the formation. Adding corrosion inhibitors can effectively avoid 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. At present, there are a variety of corrosion inhibitors at home and abroad, but they generally have disadvantages such as large dosage, low corrosion inhibition efficiency, and large side effects.

[0004] CN108018559B discloses a compound oilfield corrosion inhibitor and a preparation method thereof, comprising liquid A and liquid B with a volume ratio of 1:3, wherein the active ingredient of liquid A is mainly 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 resistant, 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 resistant and strong acid and alkali equipment such as reactors are required, which increases the operating cost, and the corrosion inhibition efficiency is only 80%.

[0005] CN107760290B discloses a bactericidal corrosion inhibitor for oilfield water treatment system and its preparation method and application method. This invention has both bactericidal and corrosion-inhibiting properties, has high bactericidal properties against sulfate-reducing bacteria (SRB) and saprophytic bacteria (TGB), has a long duration of efficacy, a simple production process and low cost, but can only inhibit CO 2 For the corrosion of metals, and the metal is carbon steel, 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 the steps of causing an imidazoline compound to react with a quaternary ammonium agent to generate an imidazoline quaternary ammonium salt. The imidazoline compound is synthesized by reacting an organic carboxylic acid with an organic polyether polyamine. The quaternary ammonium agent is a combination of one or more of dimethyl carbonate, diethyl carbonate, and ethylene carbonate. The method has low toxicity during the synthesis process and is easy to operate. However, in order 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 with the model number of OED. Summary of the invention

[0007] The present invention aims at the deficiencies 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 simple synthesis process, small dosage and good corrosion inhibition effect. When the concentration is 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, and 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: in the presence of a reducing agent, 2-acetyl-2-thiazoline and N,N-dimethylaminopropylamine undergo a reductive amination reaction in a weakly acidic solvent; secondly, in a weakly alkaline environment, the reductive amination product undergoes a tertiary amination reaction with chloroacetic acid.

[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 is a corrosion inhibitor with thiazoline, tertiary amine base and carboxylic acid as functional groups. The mechanism of action includes the following points: there are multiple adsorption centers in the corrosion inhibitor molecule, such as N, O, S can provide lone pair electrons, improve the oxidation resistance of the metal; N and tertiary amine N in thiazoline can be adsorbed on the metal surface through multiple ways such as electrostatic adsorption and formation of coordination bonds, forming a protective film to prevent the contact between the metal and the liquid; the corrosion inhibitor molecules can also adhere to the metal surface, increase the resistance of the metal, and reduce 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 cause 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 use 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] Attached 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 and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[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: in the presence of a reducing agent, 2-acetyl-2-thiazoline and N,N-dimethylaminopropylamine undergo a reductive amination reaction in a weakly acidic solvent; secondly, in a weakly alkaline environment, the reductive amination product undergoes a tertiary amination reaction with chloroacetic acid.

[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 into a four-necked flask, adjust the pH to 3-4 with hydrochloric acid, heat to 50-60° C., and keep warm to carry out a reduction 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 to below 5°C with ice water 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 corrosion inhibitor in oilfield wastewater treatment. There is no special requirement for the specific application, and it can be a conventional application in the field, 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 suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0044] In addition, 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 into a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 58°C, and keep the temperature for reductive amination reaction for 1.5 hours;

[0050] (2) adding 0.18 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 8 with a 2 mol / L sodium hydroxide solution, and reacting at 60° C. for 2 h, 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 there was no distillate, 155 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 80°C overnight to obtain a light yellow solid corrosion inhibitor product N 1 .

[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 into a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 57°C, and keep the temperature for a reductive amination reaction for 0.5 h;

[0054] (2) adding 0.26 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 9 with a 2 mol / L sodium hydroxide solution, and reacting at 70° C. for 3 h, during which the pH was maintained 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 there was no distillate, 166 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 85°C overnight to obtain a light yellow solid corrosion inhibitor product N 2 .

[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 into a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 56°C, and keep the temperature for reductive amination reaction for 1 hour;

[0058] (2) adding 0.19 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 9 with a 2 mol / L sodium hydroxide solution, and reacting at 60° C. for 1 h, 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 there was no distillate, 168 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 82°C overnight to obtain a light yellow solid corrosion inhibitor product N 3 .

[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 into a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 53°C, and keep the temperature for reductive amination reaction for 1.5 hours;

[0062] (2) adding 0.25 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 8 with a 2 mol / L sodium hydroxide solution, and reacting at 62° C. for 4 h, during which the pH was maintained 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 there was no distillate, 173 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 83°C overnight to obtain a light yellow solid corrosion inhibitor product N 4 .

[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 into a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 52°C, and keep the temperature for reductive amination reaction for 1.5 hours;

[0066] (2) adding 0.2 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 9 with a 2 mol / L sodium hydroxide solution, and reacting at 63° C. for 2 h, during which the pH was maintained 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 there was no distillate, 188 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 85°C overnight to obtain a light yellow solid corrosion inhibitor product N 5 .

[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 into a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 55°C, and keep the temperature for 2 h of reductive amination reaction;

[0070] (2) adding 0.24 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 8 with a 2 mol / L sodium hydroxide solution, and reacting at 65° C. for 3 h, during which the pH was maintained 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 there was no distillate, 180 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 85°C overnight to obtain a light yellow solid corrosion inhibitor product N 6 .

[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 into a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 55°C, and keep the temperature for 2 h of reductive amination reaction;

[0074] (2) adding 0.21 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 9 with a 2 mol / L sodium hydroxide solution, and reacting at 67° C. for 2 h, 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 there was no distillate, 195 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 82°C overnight to obtain a light yellow solid corrosion inhibitor product N 7 .

[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 into a four-necked flask, adjust the pH to 3 with 2 mol / L hydrochloric acid, heat to 60°C, and keep the temperature to carry out the reductive amination reaction for 1.5 hours;

[0078] (2) adding 0.23 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 9 with 2 mol / L sodium hydroxide solution, and reacting at 68° C. for 2 h, during which the pH was maintained 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 there was no distillate, 200 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 82°C overnight to obtain a light yellow solid corrosion inhibitor product N 8 .

[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 into a four-necked flask, adjust the pH to 4 with 2 mol / L hydrochloric acid, heat to 50°C, and keep the temperature for reductive amination reaction for 1.5 hours;

[0082] (2) adding 0.22 mol of chloroacetic acid to the above reductive amination reaction mixture, adjusting the pH to 9 with a 2 mol / L sodium hydroxide solution, and reacting at 70° C. for 2 h, during which the pH was maintained 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 there was no distillate, 206 g of distilled water was added, the pH was adjusted to 9-10 with sodium hydroxide, filtered, the filtrate was adjusted to pH 3-4, the temperature was cooled to below 5°C with ice water, crystals were precipitated, and dried at 83°C overnight to obtain a light yellow solid corrosion inhibitor product N 9 .

[0084] Example 10 Laboratory Corrosion Inhibitor Evaluation

[0085] In the laboratory, the corrosion inhibitor N 1 -N 9 The test evaluation was carried out with reference to 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. The dosing concentrations were 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) Corrosion Inhibitor N of the Present Invention 1 -N 9 When the concentration is 5mg / L, the corrosion rate is less than 0.012mm / a. 9The lowest corrosion rate reached 0.0069 mm / a, while the corrosion rate of ethylenediaminetetramethylenephosphoric acid (EDTMP) in comparative example 1 was 0.0283 mm / a, which was significantly higher than that of the present invention; when the concentration was 10 mg / L, the corrosion rate was less than 0.0085 mm / a, where N 9 The lowest corrosion rate reaches 0.0043 mm / a, while the corrosion rate of ethylenediaminetetramethylenephosphoric acid (EDTMP) in comparative example 1 is 0.0233 mm / a, which is significantly higher than that of the present invention.

[0090] (2) Corrosion Inhibitor N of the Present Invention 1 -N 9 When the concentration is 5mg / L, the corrosion inhibition rate is greater than 97%, among which N 9 The highest corrosion inhibition rate reached 98.7%, while the corrosion inhibition rate of ethylenediaminetetramethylenephosphoric acid (EDTMP) in comparative example 1 was 93.9%, which was significantly lower than that of the present invention; when the concentration was 10 mg / L, the corrosion inhibition rate was greater than 97.9%, among which N 9 The highest corrosion inhibition rate reaches 99.3%, while the corrosion inhibition rate of ethylenediaminetetramethylenephosphoric 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 station of an oil field, set up four groups of control experiments, and set up two blank groups K 1 , K 2 , two experimental groups H 1 , H 2 , each adding 10 mg / L N 8 、N 9 , placed in a 60℃ oven, taken out after 10 days, the results are shown in Figure 1 , the test results are shown in Table 2.

[0093] Table 2 Joint station water corrosion test results

[0094] Corrosion Inhibitor Corrosion rate, mm / a <![CDATA[K 1 ]]> 0.478 <![CDATA[K 2 ]]> 0.436 <![CDATA[H 1 ]]> 0.0068 <![CDATA[H 2 ]]> 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] N 8 The corrosion inhibition rate is (0.457-0.0068) / 0.457×100%=98.5%.

[0098] N 9 The corrosion inhibition rate is (0.457-0.0072) / 0.457×100%=98.4%.

[0099] The corrosion inhibitor N of the present invention 8 、N 9 The field test results are good, with a corrosion inhibition rate of more than 98%.

[0100] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope 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. A method for synthesizing an oilfield water treatment corrosion inhibitor, characterized in that: The synthesis method comprises: in the presence of a reducing agent, 2-acetyl-2-thiazoline and N,N-dimethylaminopropylamine undergo a reductive amination reaction in a weakly acidic solvent; and secondly, in a weakly alkaline environment, the reductive amination product undergoes a tertiary amination reaction with chloroacetic acid.

3. The method for synthesizing a corrosion inhibitor for oilfield water treatment according to claim 2, characterized in that: Based on 1 mole of 2-acetyl-2-thiazoline, the N,N-dimethylaminopropylamine and chloroacetic acid are 0.9-1.1 mole and 0.9-1.3 mole, respectively.

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

5. The method for synthesizing a corrosion inhibitor for oilfield water treatment according to claim 4, characterized in that: Based on 1 mole of 2-acetyl-2-thiazoline, the 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, characterized in that: 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, characterized in that: 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 a corrosion inhibitor for oilfield water treatment 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 a corrosion inhibitor for oilfield water treatment 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 0.5-2h.

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

14. The method for synthesizing a corrosion inhibitor for oilfield water treatment 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 a corrosion inhibitor for oilfield water treatment 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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