Multi-effect imidazoline corrosion inhibitor for acidizing and fracturing as well as preparation method and application of multi-effect imidazoline corrosion inhibitor

Abstract

The invention discloses a multi-effect imidazoline corrosion inhibitor for acidizing and fracturing as well as a preparation method and application thereof, and relates to the technical field of oilfield chemistry, the preparation method comprises the following steps: uniformly stirring polyethylene glycol monomethyl ether and cyanuric chloride to react to prepare a polyether cyanuric chloride solution; the preparation method comprises the following steps: stirring 5-sulfosalicylic acid, propargyl alcohol, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and 4-dimethylaminopyridine to react to prepare a 5-sulfosalicylic acid propargyl alcohol ester product, reacting the 5-sulfosalicylic acid propargyl alcohol ester product with polyether cyanuric chloride to prepare a polyether-sulfonate disubstituted cyanuric chloride intermediate, and reacting the polyether-sulfonate disubstituted cyanuric chloride intermediate with polyether cyanuric chloride to prepare the polyether-sulfonate disubstituted cyanuric chloride intermediate. Dodecenylsuccinic acid and diethylenetriamine react to prepare an imidazoline intermediate, and the polyether-sulfonate disubstituted cyanuric chloride intermediate and the imidazoline intermediate are heated to react to obtain the polyether-sulfonate disubstituted cyanuric chloride. According to the prepared multi-effect imidazoline corrosion inhibitor, four functional groups are combined through chemical bonds, the defects of physical compounding are avoided, and the corrosion inhibition efficiency far exceeding that of physical compounding is achieved.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically to a multi-effect imidazoline corrosion inhibitor for acid fracturing, its preparation method, and its application. Background Technology

[0002] In oil and gas extraction, acid fracturing is one of the main measures to improve oil and gas well recovery and increase production. However, during the implementation of acid fracturing technology, the acid solution severely corrodes metal pipes, seriously affecting the normal production of oil and gas wells. Adding acid corrosion inhibitors is an effective way to prevent corrosion of oil and gas well equipment and pipelines. Types of acid corrosion inhibitors include inorganic salts, organic amines, quaternary ammonium salts, imidazolines, and their derivatives. Among them, imidazoline and its derivatives are widely used due to their advantages such as good thermal stability, low toxicity, and good slow-release effect. However, traditional imidazoline corrosion inhibitors show a significant decrease in corrosion inhibition efficiency in harsh environments such as high temperature and high salinity, and also suffer from poor solubility and uneven dispersion.

[0003] Existing patent CN111320611A discloses a polyether-modified imidazoline corrosion inhibitor, which improves its water solubility but is insufficient for acidic environments; patent CN109678800B discloses a benzyl imidazoline cationic corrosion inhibitor, which is suitable for use in high-mineralization environments (total ion concentration greater than 2.33 × 10⁻⁶). 5 While current corrosion inhibitors (ppm) are effective in oil and gas extraction, their resistance to temperature variations is insufficient. Patent CN110042398A discloses a high-temperature resistant imidazoline corrosion inhibitor containing a fluorinated surfactant, suitable for downhole environments up to 120°C, but with poor water solubility. Patent CN104109529A discloses an acidification corrosion inhibitor, which improves performance by compounding propynyl alcohol to achieve good dispersibility; however, propynyl alcohol is highly toxic and volatile, hindering its widespread application. Therefore, given the current limitations of single-function corrosion inhibitors, developing a novel corrosion inhibitor that can combine multiple corrosion-inhibiting functional groups through stable chemical bonds within a single molecule to achieve intramolecular synergistic effects is of great significance. Summary of the Invention

[0004] In view of this, the present invention proposes a multi-effect imidazoline corrosion inhibitor for acid fracturing, its preparation method, and its application. In this invention, the corrosion inhibitor molecule integrates imidazoline adsorption groups, polyether hydrophilic segments, sulfonic acid groups with strong water solubility, and propynyl alcohol acidic corrosion inhibitor groups into one through covalent bonds, thereby achieving intramolecular multi-mechanism synergistic corrosion inhibition. This provides efficient and long-lasting protection for metal equipment in acidic, highly salinized water bodies with low injection volume.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention discloses a multi-effect imidazoline corrosion inhibitor for acid fracturing; the preparation method is described in [reference needed]. Figure 1, Figure 2 Using cyanuric chloride as the core bridging bond, the terminal hydroxyl groups of polyethylene glycol monomethyl ether, the phenolic hydroxyl groups of 5-sulfonic acid salicylic acid propynyl alcohol ester, and the secondary amino groups in the imidazoline molecule undergo substitution reactions with the chlorine in cyanuric chloride. This chemically links the polyethylene glycol segment, the sulfonic acid group, and the two imidazoline groups into a single molecule via a cyanuric chloride bridge. The active product molecule has the following structure: Where n is an integer ≥ 4.

[0006] Meanwhile, this invention also discloses a method for preparing the above-mentioned multi-effect imidazoline corrosion inhibitor for acid fracturing, comprising the following steps: Step S1: After mixing polyethylene glycol monomethyl ether and sodium hydroxide, pre-cool to 0°C, slowly add the mixture dropwise to an acetone solution of cyanuric chloride at 0°C to 5°C and stir until homogeneous. After the addition is complete, maintain the reaction temperature at 0°C to 5°C for 1 to 2 hours to obtain a polyether cyanuric chloride solution. Step S2: 5-sulfosalicylic acid, propynyl alcohol, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 4-dimethylaminopyridine are stirred and reacted at 20℃~25℃ for 2h~4h to obtain 5-sulfosalicylic acid propynyl alcohol ester product. Step S3: At 40℃~50℃, add solid sodium hydroxide to the 5-sulfonic acid salicylic acid propynyl alcohol ester product obtained in step S2, and then slowly add the mixed solution dropwise to the polyether cyanuric chloride solution obtained in step S1. Maintain the temperature and stir the reaction for 6h~8h to obtain the polyether-sulfonate cyanuric chloride intermediate. Step S4: Dodecenylsuccinic acid, diethylenetriamine and xylene are stirred and heated to 120°C in a nitrogen atmosphere filled after vacuuming, refluxed for 1h~3h, excess water is separated, and then the temperature is gradually raised to 140°C~200°C and held for 1h~2h. After evaporating the water, the mixture is cooled to obtain the imidazoline intermediate. Step S5: Mix the polyether-sulfonate disubstituted trichlorocyanurate intermediate obtained in step S3 with the imidazoline intermediate obtained in step S4, add solid sodium hydroxide, and heat to 75℃~95℃ to react for 1h~2h to obtain the final product.

[0007] Furthermore, the molar ratio of cyanuric chloride to polyethylene glycol monomethyl ether in step S1 is 1:1~2.

[0008] Furthermore, in step S2, the molar ratio of 5-sulfosalicylic acid to propynyl alcohol is 1:1.2~1.5; the molar ratio of 5-sulfosalicylic acid to 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:1.1~1.3; and the molar ratio of 5-sulfosalicylic acid to 4-dimethylaminopyridine is 1:0.1~0.3.

[0009] Furthermore, the molar ratio of the polyether cyanuric chloride and the 5-sulfonic acid salicylic acid propynyl alcohol ester product in step S3 is 1:1.0~1.1.

[0010] Furthermore, in step S4, the molar ratio of dodecenylsuccinic acid to diethylenetriamine is 1:2.1~2.2; the ratio of dodecenylsuccinic acid to xylene is 25g~27g of dodecenylsuccinic acid per 50mL of xylene.

[0011] Furthermore, in step S5, the molar ratio of the imidazoline intermediate to the polyether-sulfonate disubstituted trichlorocyanurate intermediate is 1:2.0~2.1.

[0012] Furthermore, the amount of sodium hydroxide used in steps S1, S3, and S5 is 1.2 to 1.5 times the molar amount of cyanuric chloride in step S1.

[0013] Furthermore, this invention also discloses the application of a multi-effect imidazoline corrosion inhibitor for acid fracturing, wherein the multi-effect imidazoline corrosion inhibitor for acid fracturing is suitable for 15%~20% hydrochloric acid media or 5×10 4 mg / L ~ 20×10 4 High mineralization medium with a concentration of mg / L.

[0014] Furthermore, the concentration of the paclobutrazol corrosion inhibitor for acid fracturing is 20 mg / L to 200 mg / L, preferably 50 to 100 mg / L.

[0015] The technical effects of this invention are as follows: (1) The multi-effect imidazoline corrosion inhibitor prepared by the present invention combines four functional groups through chemical bonds, avoiding the disadvantages of physical compounding and achieving corrosion inhibition efficiency far exceeding that of physical compounding. The corrosion inhibition efficiency of 50ppm corrosion inhibitor can reach 98.61% (the corrosion inhibition efficiency of physical compounding corrosion inhibitor is 92.53%).

[0016] (2) The introduction of propynyl alcohol groups into the corrosion inhibitor structure can form a polymeric protective film on the metal surface. Through intramolecular synergistic effect, it overcomes the compatibility and competitive adsorption problems of the components in physical compounding, and solves the problem that small molecule propynyl alcohol is easy to volatilize and lose, resulting in short-lasting efficacy. Through the combination of chemical adsorption and polymeric film adsorption, the protective film is stronger and has a longer effective period. It not only improves the corrosion inhibition effect of the corrosion inhibitor, but also solves the problem of traditional imidazoline failing at low pH.

[0017] (3) The corrosion inhibitor prepared in this invention introduces hydrophilic polyether segments and strongly polar sulfonic acid groups onto the cyanuric chloride backbone, which not only gives the product extremely strong solubility, but also provides huge steric hindrance through the extended polyether long chains, effectively preventing flocculation and precipitation of molecules in high-salt environments. The sulfonic acid groups are insensitive to polyvalent cations and are not prone to precipitation, so that this product can be used even in saturated salt water or high calcium and magnesium ion solutions (TDS>15×10⁻⁶). 4 It remains clear and transparent even at g / L, and its corrosion inhibition efficiency does not decrease.

[0018] (4) The corrosion inhibitor prepared by this invention has a triazine ring as the core skeleton, an imidazoline ring rigid planar structure, and a benzene ring structure, which makes the molecular structure highly thermally stable. At 150℃, this product has a corrosion inhibition rate of more than 98% for N80 steel, which fully meets the requirements of high temperature environment in deep wells.

[0019] (5) The synthesis route of this invention is reasonably designed and highly controllable. The preparation method utilizes the difference in reactivity of the three chlorine atoms of cyanuric chloride and adopts a step-by-step feeding and temperature control strategy to achieve modular and precise assembly. The reaction conditions are mild, the yield is high, and it is easy to industrialize. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the reaction principle in steps S1 to S4 of this invention; Figure 2 This is a schematic diagram of the reaction principle in step S5 of the present invention. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0022] Example 1 (1) Add 18.4 g of cyanuric chloride (dissolved in 25 mL of acetone, 100 mmol) to a dry reaction flask and place it in an ice-water bath at 0 °C; add 60.0 g of polyethylene glycol monomethyl ether (120 mmol) with a molecular weight of 500 g / mol and 5.0 g of sodium hydroxide to another round-bottom flask in sequence, pre-cool to 0 °C, and slowly add the polyethylene glycol monomethyl ether solution to the cyanuric chloride solution dropwise using a constant pressure dropping funnel under stirring conditions. After the addition is complete, continue the reaction at 0 °C for 1.5 h to obtain a polyether cyanuric chloride solution. The degree of polymerization of the polyether cyanuric chloride prepared from the polyethylene glycol monomethyl ether in this example is 11.

[0023] (2) At 25°C, 21.82 g of 5-sulfosalicylic acid (100 mmol), 6.73 g of propynyl alcohol (120 mmol), 21.09 g of condensing agent 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCL, 110 mmol), and 2.44 g of catalyst 4-dimethylaminopyridine (DMAP, 20 mmol) were added to a round-bottom flask and stirred for 3 h to obtain the 5-sulfosalicylic acid propynyl alcohol ester product.

[0024] (3) At 45°C, 5.0 g of solid sodium hydroxide was added to 20.5 g of 5-sulfonic acid salicylic acid propynyl alcohol ester (80 mmol) and slowly added dropwise to 52.0 g of polyether cyanuric chloride solution (80 mmol) through a constant pressure dropping funnel. The reaction was continued for 7 h with stirring to obtain polyether-sulfonate ester disubstituted cyanuric chloride intermediate.

[0025] (4) Add 14.22 g dodecenyl succinic acid (50 mmol), 11.35 g diethylenetriamine (110 mmol) and 28 mL xylene as a water-carrying agent to a four-necked flask equipped with a thermometer, water separator, condenser and stirrer. Vacuum the reaction apparatus, purge with nitrogen, start stirring and gradually increase the temperature. Reflux at 120 °C for 2 h to separate the water generated by the amidation reaction. Then gradually increase the temperature to 170 °C and keep it at 1.5 h to evaporate the water generated by the cyclization reaction. Finally, cool the reactants to obtain the imidazoline intermediate. (5) In a round-bottom flask, 12.56 g of imidazoline intermediate (30 mmol) and 52.18 g of polyether-sulfonate disubstituted trichlorocyanuric acid intermediate (60 mmol) were thoroughly mixed, 5.0 g of solid sodium hydroxide was added, and the mixture was heated to 85 °C and reacted for 1.5 h to obtain a water-soluble one-agent multi-effect imidazoline corrosion inhibitor.

[0026] Example 2 (1) Add 18.4 g of cyanuric chloride (dissolved in 25 mL of acetone, 100 mmol) to a dry reaction flask and place it in an ice-water bath at 0 °C; add 120.0 g of polyethylene glycol monomethyl ether (120 mmol) with a molecular weight of 1000 g / mol and 5.0 g of sodium hydroxide to another round-bottom flask in sequence, pre-cool to 0 °C, and slowly add the polyethylene glycol monomethyl ether solution to the cyanuric chloride solution dropwise using a constant pressure dropping funnel under stirring conditions. After the addition is complete, continue the reaction at 0 °C for 1.5 h to obtain a polyether cyanuric chloride solution. The degree of polymerization of the polyether cyanuric chloride prepared from the polyethylene glycol monomethyl ether in this example is 22.

[0027] (2) At 25°C, 21.82 g of 5-sulfosalicylic acid (100 mmol), 6.73 g of propynyl alcohol (120 mmol), 21.09 g of condensing agent 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCL, 110 mmol), and 2.44 g of catalyst 4-dimethylaminopyridine (DMAP, 20 mmol) were added to a round-bottom flask and stirred for 3 h to obtain the 5-sulfosalicylic acid propynyl alcohol ester product.

[0028] (3) At 45°C, 5.0 g of solid sodium hydroxide was added to 20.5 g of 5-sulfonic acid salicylic acid propynyl alcohol ester (80 mmol) and slowly added dropwise to 91.84 g of polyether cyanuric chloride solution (80 mmol) through a constant pressure dropping funnel. The reaction was continued for 7 h with stirring to obtain polyether-sulfonate cyanuric chloride intermediate.

[0029] (4) Add 14.22 g dodecenyl succinic acid (50 mmol), 11.35 g diethylenetriamine (110 mmol) and 28 mL xylene as a water-carrying agent to a four-necked flask equipped with a thermometer, water separator, condenser and stirrer. Vacuum the reaction apparatus, purge with nitrogen, start stirring and gradually increase the temperature. Reflux at 120 °C for 2 h to separate the water generated by the amidation reaction. Then gradually increase the temperature to 170 °C and keep it at 1.5 h to evaporate the water generated by the cyclization reaction. Finally, cool the reactants to obtain the imidazoline intermediate. (5) In a round-bottom flask, 12.56 g of imidazoline intermediate (30 mmol) and 82.06 g of polyether-sulfonate disubstituted trichlorocyanuric acid intermediate (60 mmol) were thoroughly mixed, 5.0 g of solid sodium hydroxide was added, and the mixture was heated to 85 °C and reacted for 1.5 h to obtain a water-soluble one-agent multi-effect imidazoline corrosion inhibitor.

[0030] Example 3 (1) Add 18.4 g of cyanuric chloride (dissolved in 25 mL of acetone, 100 mmol) to a dry reaction flask and place it in an ice-water bath at 0 °C; add 240.0 g of polyethylene glycol monomethyl ether (120 mmol) with a molecular weight of 2000 g / mol and 5.0 g of sodium hydroxide to another round-bottom flask in sequence, pre-cool to 0 °C, and slowly add the polyethylene glycol monomethyl ether solution to the cyanuric chloride solution with a constant pressure dropping funnel under stirring. After the addition is complete, continue the reaction at 0 °C for 1.5 h to obtain a polyether cyanuric chloride solution. The degree of polymerization of the polyether cyanuric chloride prepared from the polyethylene glycol monomethyl ether in this example is 45.

[0031] (2) At 25°C, 21.82 g of 5-sulfosalicylic acid (100 mmol), 6.73 g of propynyl alcohol (120 mmol), 21.09 g of condensing agent 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCL, 110 mmol), and 2.44 g of catalyst 4-dimethylaminopyridine (DMAP, 20 mmol) were added to a round-bottom flask and stirred for 3 h to obtain the 5-sulfosalicylic acid propynyl alcohol ester product.

[0032] (3) At 45°C, 5.0 g of solid sodium hydroxide was added to 20.5 g of 5-sulfonic acid salicylic acid propynyl alcohol ester (80 mmol) and slowly added dropwise to 171.84 g of polyether cyanuric chloride solution (80 mmol) through a constant pressure dropping funnel. The reaction was continued for 7 h with stirring to obtain polyether-sulfonate cyanuric chloride intermediate.

[0033] (4) Add 14.22 g dodecenyl succinic acid (50 mmol), 11.35 g diethylenetriamine (110 mmol) and 28 mL xylene as a water-carrying agent to a four-necked flask equipped with a thermometer, water separator, condenser and stirrer. Vacuum the reaction apparatus, purge with nitrogen, start stirring and gradually increase the temperature. Reflux at 120 °C for 2 h to separate the water generated by the amidation reaction. Then gradually increase the temperature to 170 °C and keep it at 1.5 h to evaporate the water generated by the cyclization reaction. Finally, cool the reactants to obtain the imidazoline intermediate. (5) In a round-bottom flask, 12.56 g of imidazoline intermediate (30 mmol) and 142.06 g of polyether-sulfonate disubstituted trichlorocyanurate intermediate (60 mmol) were thoroughly mixed, 5.0 g of solid sodium hydroxide was added, and the mixture was heated to 85 °C and reacted for 1.5 h to obtain a water-soluble one-agent multi-effect imidazoline corrosion inhibitor.

[0034] Comparative Example 1 The preparation method of this comparative example is basically the same as that of Example 1. The main difference is that propynyl alcohol is not involved in the synthesis reaction, and therefore it lacks the strong adsorption and film-forming advantages brought by the alkynyl group in terms of corrosion inhibition principle. Specifically: (1) Add 18.4 g of cyanuric chloride (dissolved in 25 mL of acetone, 100 mmol) to a dry reaction flask and place it in an ice-water bath at 0 °C; add 60.0 g of polyethylene glycol monomethyl ether (120 mmol) with a molecular weight of 500 g / mol and 5.0 g of sodium hydroxide to another round-bottom flask in sequence, pre-cool to 0 °C, and slowly add the polyethylene glycol monomethyl ether solution to the cyanuric chloride solution dropwise using a constant pressure dropping funnel under stirring conditions. After the addition is complete, continue the reaction at 0 °C for 1.5 h to obtain a polyether cyanuric chloride solution.

[0035] (2) At 45°C, 5.0g of solid sodium hydroxide was added to 17.45g of 5-sulfonic acid salicylic acid (80mmol) and slowly added dropwise to 52.0g of polyether cyanuric chloride (80mmol) solution through a constant pressure dropping funnel. The reaction was continued for 7h with stirring to obtain cyanuric chloride substituted intermediate.

[0036] (3) Add 14.22g dodecenylsuccinic acid (50mmol), 11.35g diethylenetriamine (110mmol) and 30mL xylene as a water-carrying agent to a four-necked flask equipped with a thermometer, water separator, condenser and stirrer. Vacuum the reaction apparatus, purge with nitrogen, start stirring and gradually raise the temperature. Reflux at 120°C for 2h to separate the water generated by the amidation reaction. Then gradually raise the temperature to 170°C and keep it at 1.5h to evaporate the water generated by the cyclization reaction. Finally, cool the reactants to obtain the imidazoline intermediate. (4) In a round-bottom flask, 12.56 g of imidazoline intermediate (30 mmol) and 50.0 g of cyanuric chloride substituted intermediate (60 mmol) were thoroughly mixed, 5.0 g of solid sodium hydroxide was added, and the mixture was heated to 85 °C and reacted for 1.5 h to obtain a water-soluble one-agent multi-effect imidazoline corrosion inhibitor.

[0037] Comparative Example 2 The preparation method of this comparative example is basically the same as that of Example 1, the main difference being that propynyl alcohol is not involved in the synthesis reaction, and the reaction product is subsequently mixed with propynyl alcohol at a molar ratio of 1:2, specifically: (1) Add 18.4 g of cyanuric chloride (dissolved in 25 mL of acetone, 100 mmol) to a dry reaction flask and place it in an ice-water bath at 0 °C; add 60.0 g of polyethylene glycol monomethyl ether (120 mmol) with a molecular weight of 500 g / mol and 5.0 g of sodium hydroxide to another round-bottom flask in sequence, pre-cool to 0 °C, and slowly add the polyethylene glycol monomethyl ether solution to the cyanuric chloride solution dropwise using a constant pressure dropping funnel under stirring conditions. After the addition is complete, continue the reaction at 0 °C for 1.5 h to obtain a polyether cyanuric chloride solution.

[0038] (2) At 45°C, 5.0g of solid sodium hydroxide was added to 17.45g of 5-sulfonic acid salicylic acid (80mmol) and slowly added dropwise to 52.0g of polyether cyanuric chloride (80mmol) solution through a constant pressure dropping funnel. The reaction was continued for 7h with stirring to obtain cyanuric chloride substituted intermediate.

[0039] (3) Add 14.22g dodecenylsuccinic acid (50mmol), 11.35g diethylenetriamine (110mmol) and 30mL xylene as a water-carrying agent to a four-necked flask equipped with a thermometer, water separator, condenser and stirrer. Vacuum the reaction apparatus, purge with nitrogen, start stirring and gradually raise the temperature. Reflux at 120°C for 2h to separate the water generated by the amidation reaction. Then gradually raise the temperature to 170°C and keep it at 1.5h to evaporate the water generated by the cyclization reaction. Finally, cool the reactants to obtain the imidazoline intermediate. (4) In a round-bottom flask, 12.56 g of imidazoline intermediate (30 mmol) and 50.0 g of cyanuric chloride substituted intermediate (60 mmol) were thoroughly mixed, 5.0 g of solid sodium hydroxide was added, and the mixture was heated to 85 °C and reacted for 1.5 h to obtain a water-soluble imidazoline corrosion inhibitor.

[0040] (5) The comparative product was obtained by compounding 40.18g of water-soluble imidazoline corrosion inhibitor (20mmol) with 2.24g of propynyl alcohol (40mmol).

[0041] Comparative Example 3 In this comparative example, a commercial corrosion inhibitor (Shandong Huayou Water Treatment, a corrosion inhibitor synthesized from oleic acid and diethylenetriamine) was used instead of the corrosion inhibitor in Example 1.

[0042] Performance testing (1) Corrosion rate determination Referring to section 7.1.2.2 of SY / T 5405-2019 "Test Methods and Evaluation of Corrosion Inhibitors for Acidification," the corrosion rate of the acid systems in each example and comparative example was tested to assess their corrosion inhibition effect. The experimental temperature (150℃) and rotation speed (60 r / min) were set, the acid solution was 20% HCl, the experimental pressure was 16 MPa, the reaction time was 4 h, and N80 steel sheets were used. The corrosion rate was calculated using the following formula: In the formula: V i —Single-piece corrosion rate, g / (m²) 2 ·h); △ t —Reaction time, h; △ m i —The corrosion vector of this piece, g; A i —Surface area of ​​the piece, mm 2 .

[0043] The corrosion inhibition efficiency is calculated using the following formula: ; In the formula: W 1—The corrosion rate of metal without corrosion inhibitors; W 0 — Corrosion rate of metal with added corrosion inhibitor.

[0044] The corrosion rates and corrosion inhibition efficiencies of the acid systems in different embodiments and comparative examples are shown in Table 1.

[0045] Table 1. Corrosion inhibition effect of acid solution system As shown in Table 1, at 150℃, the corrosion inhibition efficiency of the 50ppm concentration used in Examples 1 to 3 can all reach over 98%, indicating that the multi-effect imidazoline corrosion inhibitor for acid fracturing of the present invention has good temperature resistance and high-efficiency corrosion inhibition performance at low concentration, meeting the requirements of on-site construction.

[0046] Meanwhile, as can be seen from Example 1 and Comparative Examples 1 to 3, Comparative Example 1, lacking propynyl alcohol, exhibits a significantly reduced corrosion inhibition efficiency. In Comparative Example 2, through physical compounding with propynyl alcohol, the synergistic effect is unstable due to compatibility and competitive adsorption issues inherent in physically compounded corrosion inhibitors. Although its overall corrosion inhibition efficiency is higher than that of Comparative Example 1, its release efficiency is still lower than that of the examples. Furthermore, in Comparative Example 3, a commercially available corrosion inhibitor (a corrosion inhibitor synthesized from oleic acid and diethylenetriamine) exhibits a limited functional scope, resulting in a 50 ppm release efficiency of only 85.96%, significantly lower than that of the examples and the other comparative examples.

[0047] To further investigate the salt resistance of this invention, a simulated salt Cl was prepared with reference to the industry standard SY / T 5273-2014 "Performance Inhibitors and Evaluation Methods for Oilfield Produced Water Treatment". - The content was 25683 mg / L, and the total mineralization was 4.2 × 10⁻⁶. 4 mg / L. The corrosion inhibition performance of N80 steel sheets was tested at an experimental temperature of 90℃, a CO2 partial pressure of 6.0MPa, and a corrosion inhibitor concentration of 100mg / L for 24h. The experimental results are shown in Table 2.

[0048] Table 2 Evaluation of the salt resistance performance of the system Table 2 shows that in simulated saline solution Cl - The content was 25683 mg / L, and the total mineralization was 4.2 × 10⁻⁶. 4 The controlled-release efficiency of mg / L in Examples 1-3 was greater than 95%, indicating that it had a good corrosion inhibition effect under high mineralization conditions. Comparative Examples 1-3 showed lower corrosion inhibition efficiency due to poorer synergistic effect.

[0049] (2) Dissolution and dispersion performance test By mixing a brine solution containing 1000 ppm corrosion inhibitor (deionized water, 3% NaCl, saturated NaCl, high calcium and magnesium ion concentration, TDS > 15 × 10⁻⁶) with a uniform concentration of 1000 ppm corrosion inhibitor... 4 The compatibility of Examples 1 to 3 and Comparative Examples 1 to 3 (g / L) was investigated at room temperature and 90℃. The test results are shown in Tables 3 and 4.

[0050] Table 3. Compatibility test results after standing at room temperature for 24 hours Table 4. Compatibility test results after standing at 90℃ for 7 days As can be seen from Tables 3 and 4, the corrosion inhibitors of Examples 1 to 3 of the present invention are clear and transparent in deionized water, 3% NaCl, saturated NaCl, and high calcium and magnesium ion concentrations, and have good salt resistance.

[0051] In Comparative Example 1, the absence of propynyl alcohol in the synthesis reaction resulted in high carboxyl group activity and significant steric hindrance, leading to the formation of byproducts. The unprotected carboxyl group readily formed insoluble calcium / magnesium precipitates in a high calcium and magnesium ion environment.

[0052] In Comparative Example 2, the unmodified intermediate was simply physically mixed with propynyl alcohol, and the dispersibility was significantly worse than that of the present invention.

[0053] Comparative Example 3: A certain commercial corrosion inhibitor lacks the water solubility improvement of polyether chains and sulfonic acid groups, resulting in poor solubility and dispersibility.

[0054] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of the claims.

Claims

1. A plethora of imidazoline corrosion inhibitors for acid fracturing, characterized in that, A molecule is formed by chemically linking a polyethylene glycol segment, a sulfonic acid group, and two imidazoline groups through a cyanuric chloride bridge. The active product molecule has the following structure: Where n is an integer ≥ 4.

2. The preparation method of the plethora-effect imidazoline corrosion inhibitor for acid fracturing as described in claim 1, characterized in that, Includes the following steps: Step S1: After mixing polyethylene glycol monomethyl ether and sodium hydroxide, pre-cool to 0°C, slowly add the mixture dropwise to an acetone solution of cyanuric chloride at 0°C to 5°C and stir until homogeneous. After the addition is complete, maintain the reaction temperature at 0°C to 5°C for 1 to 2 hours to obtain a polyether cyanuric chloride solution. Step S2: 5-sulfosalicylic acid, propynyl alcohol, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 4-dimethylaminopyridine are stirred and reacted at 20℃~25℃ for 2h~4h to obtain 5-sulfosalicylic acid propynyl alcohol ester product. Step S3: At 40℃~50℃, add solid sodium hydroxide to the 5-sulfonic acid salicylic acid propynyl alcohol ester product obtained in step S2, and then slowly add the mixed solution dropwise to the polyether cyanuric chloride solution obtained in step S1. Maintain the temperature and stir the reaction for 6h~8h to obtain the polyether-sulfonate cyanuric chloride intermediate. Step S4: Dodecenylsuccinic acid, diethylenetriamine and xylene are stirred and heated to 120°C in a nitrogen atmosphere filled after vacuuming, refluxed for 1h~3h, excess water is separated, and then the temperature is gradually raised to 140°C~200°C and held for 1h~2h. After evaporating the water, the mixture is cooled to obtain the imidazoline intermediate. Step S5: Mix the polyether-sulfonate disubstituted trichlorocyanurate intermediate obtained in step S3 with the imidazoline intermediate obtained in step S4, add solid sodium hydroxide, and heat to 75℃~95℃ to react for 1h~2h to obtain the final product.

3. The preparation method of the multi-effect imidazoline corrosion inhibitor for acid fracturing according to claim 2, characterized in that: The molar ratio of cyanuric chloride to polyethylene glycol monomethyl ether in step S1 is 1:1~2.

4. The preparation method of a multi-effect imidazoline corrosion inhibitor for acid fracturing according to claim 2, characterized in that: In step S2, the molar ratio of 5-sulfosalicylic acid to propynyl alcohol is 1:1.2~1.5; the molar ratio of 5-sulfosalicylic acid to 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:1.1~1.3; and the molar ratio of 5-sulfosalicylic acid to 4-dimethylaminopyridine is 1:0.1~0.

3.

5. The preparation method of a multi-effect imidazoline corrosion inhibitor for acid fracturing according to claim 2, characterized in that: The molar ratio of the polyether cyanuric chloride and the 5-sulfonic acid salicylic acid propynyl alcohol ester product in step S3 is 1:1.0~1.

1.

6. The preparation method of a multi-effect imidazoline corrosion inhibitor for acid fracturing according to claim 2, characterized in that: In step S4, the molar ratio of dodecenylsuccinic acid to diethylenetriamine is 1:2.1~2.2; the ratio of dodecenylsuccinic acid to xylene is 25g~27g of dodecenylsuccinic acid per 50mL of xylene.

7. The preparation method of a multi-effect imidazoline corrosion inhibitor for acid fracturing according to claim 2, characterized in that: The molar ratio of the imidazoline intermediate to the polyether-sulfonate disubstituted trichlorocyanurate intermediate in step S5 is 1:2.0~2.

1.

8. The method for preparing a multi-effect imidazoline corrosion inhibitor for acid fracturing according to claim 2, characterized in that: The amount of sodium hydroxide used in steps S1, S3, and S5 is 1.2 to 1.5 times the molar amount of cyanuric chloride in step S1.

9. The application of the plethora of imidazoline corrosion inhibitors for acid fracturing as described in claim 1, characterized in that: The aforementioned multi-effect imidazoline corrosion inhibitor for acid fracturing is suitable for 15%~20% hydrochloric acid media or 5×10 4 mg / L ~ 20×10 4 High mineralization medium with a concentration of mg / L.

10. The application of the multi-effect imidazoline corrosion inhibitor for acid fracturing according to claim 9, characterized in that: The concentration of the plethora-imidazoline corrosion inhibitor used for acid fracturing is 20 mg / L to 200 mg / L.

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