Acid liquid system based on synergistic interaction of corrosion inhibitor and iron stabilizer and preparation method

Abstract

The invention discloses an acid liquid system based on synergistic interaction of a corrosion inhibitor and an iron stabilizer and a preparation method, and relates to the technical field of oilfield chemistry, the acid liquid system comprises the following components by mass: 10%-20% of an acid liquid, 0.5%-3% of a composite corrosion inhibitor, 0.5%-2% of an iron stabilizer, 0.1%-0.5% of a discharge aiding agent, 0.2%-0.8% of an acid thickening agent, and the balance of water; the main component of the composite corrosion inhibitor in the acid liquid system is long-chain alkyl bis-imidazoline-thiadiazole amide hydroxypropyl sulfobetaine, and the composite corrosion inhibitor contains a bis-imidazoline ring and a thiadiazole amide ring, and can form more stable multi-active-site adsorption on the metal surface to form a compact and stable protective film, so that the metal surface corrosion resistance is improved, and the metal surface corrosion resistance is improved. Long carbon chains in molecules can effectively block corrosive media, N, O and S heteroatoms in the molecules are adsorbed on the iron surface through lone pair electrons to inhibit corrosion, the slow-release effect is further enhanced, and therefore the slow-release efficiency is improved by 40% or above.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically to an acid system and its preparation method based on the synergistic effect of corrosion inhibitors and iron stabilizers. Background Technology

[0002] Acidizing is an important production enhancement measure in oil and gas extraction. By injecting acid into the formation, it dissolves the formation rocks, improves formation permeability, and thus increases oil and gas production. However, existing acid systems have several problems. On the one hand, acid severely corrodes metal pipes, shortening the service life of oil and gas wells and increasing extraction costs. On the other hand, iron ions generated by the reaction of acid with formation rocks are prone to precipitation and migration, causing formation contamination and reducing acidizing effectiveness. Although some corrosion inhibitors and iron stabilizers are currently used in acid systems, many additives in the acid are based on simple combinations or have antagonistic effects, leading to a decline in overall performance and failing to fully realize synergistic effects, thus failing to meet the actual needs of oil and gas extraction. Therefore, developing an acid system based on the synergistic effect of corrosion inhibitors and iron stabilizers is of great significance. Summary of the Invention

[0003] In view of this, the present invention proposes an acid system and preparation method based on the synergistic effect of corrosion inhibitor and iron stabilizer. The acid system has the characteristics of good additive compatibility, temperature resistance up to 180℃, low corrosion rate, strong ability to stabilize iron ions, simple formula and readily available raw materials, which is more conducive to large-scale on-site construction application.

[0004] This invention discloses an acid solution system based on the synergistic effect of corrosion inhibitors and iron stabilizers, comprising the following components by mass fraction:

[0005]

[0006] The remainder is water.

[0007] One embodiment of the present invention comprises, by mass fraction, the composite sustained-release agent comprising the following components:

[0008]

[0009] The remainder is water.

[0010] Furthermore, the main component of the corrosion inhibitor is a long-chain alkyl diimidazoline-thiadiazole amide hydroxypropanesulfonyl betaine corrosion inhibitor, and its preparation method includes the following steps:

[0011] Step 1: Reconstitute diethylenetriamine with long-chain fatty acids (carbon chain C... 11 ~C 18After mixing the reactants at a molar ratio of 1.2:1, xylene, a water-carrying agent, was added. The mass ratio of reactants to xylene was 1:0.8-1. After evacuation, the mixture was stirred and gradually heated to 120°C under a nitrogen atmosphere. The mixture was then refluxed for 1-3 hours to separate the water produced by the reaction. The mixture was then gradually heated to 140°C-200°C and held for 1-2 hours to evaporate the water produced by the cyclization reaction. After cooling, the imidazoline intermediate was obtained.

[0012] Step 2: In a 10% NaOH aqueous solution, 2,5-dimercaptothiadiazole and sodium chloroacetate were added sequentially at 55℃~70℃. The reaction was carried out for 3~4 hours, cooled, and the pH was adjusted to 2-3 with dilute hydrochloric acid. The target substance was precipitated, filtered, washed with cold water, and dried to obtain 2,5-bis(carboxymethylthio)-1,3,4-thiadiazole.

[0013] Step 3: At a temperature of 120℃~200℃, using phosphorus pentoxide as a dehydrating agent, mix the imidazoline intermediate obtained in Step 1 and the 2,5-bis(carboxymethylthio)-1,3,4-thiadiazole obtained in Step 2, and heat to 180℃ for 2~3h to obtain a long-chain alkyl bisimidazoline-thiadiazole amide corrosion inhibitor.

[0014] Step 4: Heat the long-chain alkyl diimidazoline-thiadiazole amide corrosion inhibitor obtained in Step 3 and sodium 3-chloro-2-hydroxybenzenesulfonate to 80-90℃, adjust the pH of the system to 7.5-8.0, and then continue the reaction for 2-3 hours to obtain the product long-chain alkyl diimidazoline-thiadiazole amide hydroxypropanesulfonate betaine corrosion inhibitor, the structural formula of which is as follows:

[0015]

[0016] Where R represents a carbon chain number of C 11 ~C 18 Saturated alkyl group, carbon chain number C 11 ~C 18 The monoalkenyl group has a carbon chain number of C. 11 ~C 18 Any of the diene groups; for specific preparation procedures, please refer to [link to documentation]. Figure 1 .

[0017] Furthermore, the solubilizer is one or more combinations of methanol, ethanol, isopropanol, butanol, n-butanol, isobutanol, ethylene glycol methyl ether, ethylene glycol diethyl ether, and ethylene glycol butyl ether.

[0018] The synergist is one or more combinations of potassium iodide, cuprous iodide, copper iodide, cuprous chloride, antimony oxide, formamide, antimonyate, propynyl alcohol, ethoxypropynyl alcohol, and propoxypropynyl alcohol. Preferably, the synergist is KI (potassium iodide).

[0019] The surfactant is one or more combinations of OP-10, Tween-20, Tween-40, Tween-60, Tween-80, S-20, S-40, S-60, and S-80.

[0020] One embodiment of the present invention comprises, by mass fraction, the iron stabilizer comprising the following components:

[0021]

[0022]

[0023] The remainder is water.

[0024] Furthermore, the main chelating agent is one or more combinations of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphate, ethylenediaminetetraacetic acid and its disodium salt, and citric acid;

[0025] The co-chelating agent is one or more of sodium lignosulfonate, thiourea, and alkyl mercaptan;

[0026] The reducing agent is one or more combinations of isoascorbic acid and sodium isoascorbate;

[0027] The iron-stabilizing synergist is one or more of the following: glucose, sodium gluconate, pregelatinized starch, carboxymethyl starch, maltodextrin, zinc sulfate, zinc chloride, zinc carbonate, basic zinc carbonate, and zinc gluconate.

[0028] Furthermore, the main chelating agent is a combination of 2-phosphonobutane-1,2,4-tricarboxylic acid and hydroxyethylidene diphosphate, with a mass ratio of 1 to 4:1.

[0029] The co-chelating agent is sodium lignosulfonate;

[0030] The isoascorbic acid;

[0031] The iron-stabilizing synergist is a combination of glucose and zinc sulfate, with a mass ratio of 2:1.

[0032] One embodiment of the present invention is that the acid solution is one or a combination of hydrochloric acid and hydrofluoric acid, and when the acid solution is a combination of hydrochloric acid and hydrofluoric acid, the volume ratio of hydrochloric acid to hydrofluoric acid is 1 to 4:1.

[0033] The drainage aid is one or more combinations of fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene-polyoxypropylene ether, nonylphenol polyoxypropylene ether, octylphenol polyoxybutylene ether, and sodium dodecyl sulfate.

[0034] One embodiment of the present invention is that, by mass fraction, the acid thickener is prepared from the following component raw materials:

[0035]

[0036] The remainder is water;

[0037] The cationic monomer is methacryloyloxyethyltrimethylammonium chloride; the hydrophobic monomer is a mixture of dimethylallyl-N-alkylammonium chloride and vinyl methacrylate, preferably in a mass ratio of 1:1.5 to 2; the salt-resistant monomer is 2-acrylamido-2-methylpropanesulfonic acid; the co-solvent is nonylphenol polyoxyethylene ether; and the initiator is a mixture of azobisisobutyronitrile, ammonium persulfate, and sodium bisulfite, in a mass ratio of 1:0.5 to 1:0.8 to 1.2.

[0038] The preparation method of the thickener for acid includes the following steps:

[0039] Acrylamide was dissolved in water, and cationic monomers, hydrophobic monomers, salt-resistant monomers, and cosolvents were added sequentially to obtain a mixture. After complete dissolution, the pH was adjusted to 7 with sodium hydroxide. Nitrogen gas was introduced while stirring, and a composite initiation system was added at -10℃ to 0℃ to initiate the reaction. After cooling to room temperature, the mixture was hydrolyzed, dried, and granulated to obtain an acid thickener.

[0040] Furthermore, this invention also discloses a method for preparing the above-mentioned acid system based on the synergistic effect of corrosion inhibitors and iron stabilizers, comprising the following steps:

[0041] Prepare a base acid solution by adding water according to the component dosage. Slowly add the composite corrosion inhibitor to the base acid solution and stir for 30 minutes to fully dissolve the composite corrosion inhibitor. Then add the iron stabilizer and continue stirring for 30-60 minutes. After the iron stabilizer is completely dissolved, add the drainage aid and stir evenly. Finally, add the acid thickener and stir for 30-60 minutes to obtain an acid solution system based on the synergistic effect of the corrosion inhibitor and the iron stabilizer.

[0042] The technical effects of this invention are as follows:

[0043] (1) The long-chain alkyl bisimidazolin-thiadiazole amide hydroxypropanesulfonate betaine corrosion inhibitor prepared in this invention contains bisimidazolin ring and thiadiazole amide ring, which can form a more stable multi-active site adsorption on the metal surface, forming a dense and stable protective film. The long carbon chain in the molecule can effectively block the corrosive medium, and the N, O, and S heteroatoms in the molecule can inhibit corrosion on the iron surface through lone pair electron adsorption, further enhancing the slow release effect. The main agent of the slow release agent, through the synergistic effect of KI and sodium lignosulfonate, produces multi-center chemisorption when in contact with the metal, thereby increasing the slow release efficiency by more than 40%.

[0044] (2) The introduction of active groups -OH, -SO3-, and -CONH- into the structure of the corrosion inhibitor makes the corrosion inhibitor have extremely strong solubility, dispersibility, and stability in strong acids.

[0045] (3) The main chelating agents PBTC and HEDP, through a double chelating network, and sodium lignosulfonate, have both dispersing and sustained-release effects, Zn 2+ The reaction with dehydroascorbic acid to form Zn-dehydroascorbate enhances the density of the cathode deposition film. Isoascorbic acid will... 3+ Fe reduction 2+ By reducing and blocking precipitation at its source, and simultaneously promoting the formation of a more uniform γ-FeOOH film through KI catalysis, the system stabilizes Fe through reduction-blocking, synergistic complexation, and interface enhancement. 3+ It can reach 925 mg / L.

[0046] (4) The selected main corrosion inhibitor and key components such as sodium lignosulfonate have low biotoxicity and are easy to degrade, overcoming the environmental defects of traditional alkynol and aldehyde corrosion inhibitors.

[0047] (5) There is no antagonism between the components of this acid system; they promote each other and have good compatibility and synergy. Attached Figure Description

[0048] Figure 1 The reaction flow diagram for preparing the main corrosion inhibitor in the composite corrosion inhibitor of this invention is shown below;

[0049] Figure 2 This is a diagram showing the effect of the acid solution system on the hydrophilicity and hydrophobicity of the test steel sheet surface in this invention. Detailed Implementation

[0050] 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.

[0051] Example 1

[0052] This embodiment provides an acid solution system based on the synergistic effect of corrosion inhibitors and iron stabilizers, comprising, by mass percentage:

[0053] 20% acid, 3% composite corrosion inhibitor, 0.5% iron stabilizer, 0.3% drainage aid, 0.6% acid thickener, and the balance is water.

[0054] Its preparation method is as follows:

[0055] Prepare a base acid solution by adding water according to the component dosage. Slowly add the composite corrosion inhibitor to the base acid solution and stir for 30 minutes to fully dissolve the composite corrosion inhibitor. Then add the iron stabilizer and continue stirring for 30-60 minutes. After the iron stabilizer is completely dissolved, add the drainage aid and stir evenly. Finally, add the acid thickener and stir for 30-60 minutes to obtain an acid solution system based on the synergistic effect of the corrosion inhibitor and the iron stabilizer.

[0056] In this embodiment, the composite corrosion inhibitor is composed of 35% slow-release agent, 20% solubilizer, 5% synergist, 2% surfactant, and the remainder is water.

[0057] In this embodiment, the main slow-release agent is an imidazoline derivative corrosion inhibitor, specifically a long-chain alkyl bisimidazoline-thiadiazole amide hydroxypropanesulfonyl betaine corrosion inhibitor, which is prepared by the following steps:

[0058] (1) Diethylenetriamine and oleic acid were added to a four-necked flask equipped with a thermometer, condenser, water separator and stirrer at a molar ratio of 1.2:1. Xylene, a water-carrying agent, was added. The mass ratio of reactants to xylene was 1:1. The reaction apparatus was evacuated and filled with nitrogen. The stirring was started and the temperature was gradually increased. The mixture was refluxed at 120°C for 3 hours to separate the water generated by the amidation reaction. The temperature was then gradually increased to 200°C and held for 2 hours to evaporate the water generated by the cyclization reaction. Finally, the reactants were cooled to obtain the imidazoline intermediate.

[0059] (2) In a 10% NaOH aqueous solution, 2,5-dimercaptothiadiazole and sodium chloroacetate were added sequentially at 70℃. The reaction was carried out for 4 hours, cooled, and the pH was adjusted to 3 with dilute hydrochloric acid. The target substance was precipitated, filtered, washed with cold water, dried and purified to obtain 2,5-di(carboxymethylthio)-1,3,4-thiadiazole.

[0060] (3) At 200℃, using phosphorus pentoxide as a dehydrating agent, the imidazoline intermediate obtained in step (1) and the 2,5-bis(carboxymethylthio)-1,3,4-thiadiazole obtained in step (2) were mixed, heated to 180℃, and reacted at a constant temperature for 3h to obtain a long-chain alkyl bisimidazoline-thiadiazole amide corrosion inhibitor.

[0061] (4) The long-chain alkyl bisimidazolin-thiadiazole amide corrosion inhibitor obtained in step (3) above and sodium 3-chloro-2-hydroxybenzenesulfonate are heated to 90°C, the pH of the system is adjusted to 8.0, and then the reaction is continued for 3 hours to obtain the product long-chain alkyl bisimidazolin-thiadiazole amide hydroxypropanesulfonate betaine corrosion inhibitor.

[0062] In this embodiment, the solubilizer is methanol, the synergist is potassium iodide, and the surfactant is OP-10.

[0063] In this embodiment, the iron stabilizer is composed of 35% main chelating agent, 25% auxiliary chelating agent, 10% reducing agent, 8% iron stabilizing synergist, and the remainder is water.

[0064] In this embodiment, the main chelating agent is a complex of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and hydroxyethylidene diphosphate (HEDP) in a mass ratio of 3:1. The auxiliary chelating agent is sodium lignosulfonate, the reducing agent is isoascorbic acid, and the synergist is glucose and zinc sulfate in a mass ratio of 2:1.

[0065] In this embodiment, the acid solution is hydrochloric acid, and the drainage aid is a mixture of fatty alcohol polyoxyethylene ether, octylphenol polyoxybutylene ether, and sodium dodecyl sulfate in a ratio of 2:1:1.

[0066] In this embodiment, a mixture was prepared by sequentially dissolving 30% acrylamide, 10% cationic monomer, 8% hydrophobic monomer, 12% salt-resistant monomer, and 3% cosolvent in water. After complete dissolution, the pH was adjusted to 7 with sodium hydroxide. Nitrogen gas was introduced while stirring, and a composite initiation system was added at -10°C to initiate the reaction. After cooling to room temperature, the mixture was hydrolyzed, dried, and granulated to obtain an acid thickener.

[0067] In this embodiment, the cationic monomer is methacryloyloxyethyltrimethylammonium chloride; the hydrophobic monomer is a mixture of dimethylallyl-N-alkylammonium chloride and vinyl methacrylate, with a mass ratio of 1:1.8; the salt-resistant monomer is 2-acrylamido-2-methylpropanesulfonic acid (AMPS); the co-solvent is nonylphenol polyoxyethylene ether; and the composite initiation system is a mixture of azobisisobutyronitrile, ammonium persulfate, and sodium bisulfite, with a mass ratio of 1:0.8:1.0.

[0068] Example 2

[0069] This embodiment provides an acid solution system based on the synergistic effect of corrosion inhibitors and iron stabilizers, comprising, by mass percentage:

[0070] 20% acid, 3% composite corrosion inhibitor, 0.5% iron stabilizer, 0.3% drainage aid, 0.6% acid thickener, and the balance is water.

[0071] Its preparation method is as follows:

[0072] Prepare a base acid solution by adding water according to the component dosage. Slowly add the composite corrosion inhibitor to the base acid solution and stir for 30 minutes to fully dissolve the composite corrosion inhibitor. Then add the iron stabilizer and continue stirring for 30-60 minutes. After the iron stabilizer is completely dissolved, add the drainage aid and stir evenly. Finally, add the acid thickener and stir for 30-60 minutes to obtain an acid solution system based on the synergistic effect of the corrosion inhibitor and the iron stabilizer.

[0073] In this embodiment, the composite corrosion inhibitor is composed of 35% slow-release agent, 20% solubilizer, 5% synergist, 2% surfactant, and the remainder is water.

[0074] In this embodiment, the main slow-release agent is an imidazoline derivative corrosion inhibitor, specifically a long-chain alkyl bisimidazoline-thiadiazole amide hydroxypropanesulfonyl betaine corrosion inhibitor, which is prepared by the following steps:

[0075] (1) Diethylenetriamine and oleic acid were added to a four-necked flask equipped with a thermometer, condenser, water separator and stirrer at a molar ratio of 1.2:1. Xylene was added as a water-carrying agent. The mass ratio of reactants to xylene was 1:1. The reaction apparatus was evacuated and filled with nitrogen. The stirring was started and the temperature was gradually increased. The mixture was refluxed at 120°C for 3 hours to separate the water generated by the amidation reaction. The temperature was then gradually increased to 200°C and held for 2 hours to evaporate the water generated by the cyclization reaction. Finally, the reactants were cooled to obtain the imidazoline intermediate.

[0076] (2) In a 10% NaOH aqueous solution, 2,5-dimercaptothiadiazole and sodium chloroacetate were added sequentially at 70℃. The reaction was carried out for 4 hours, cooled, and the pH was adjusted to 3 with dilute hydrochloric acid. The target substance was precipitated, filtered, washed with cold water, dried and purified to obtain 2,5-di(carboxymethylthio)-1,3,4-thiadiazole.

[0077] (3) At 200℃, using phosphorus pentoxide as a dehydrating agent, the imidazoline intermediate obtained in step (1) and the 2,5-bis(carboxymethylthio)-1,3,4-thiadiazole obtained in step (2) were mixed, heated to 180℃, and reacted at a constant temperature for 3h to obtain a long-chain alkyl bisimidazoline-thiadiazole amide corrosion inhibitor.

[0078] (4) The long-chain alkyl bisimidazolin-thiadiazole amide corrosion inhibitor obtained in step (3) above and sodium 3-chloro-2-hydroxybenzenesulfonate are heated to 90°C, the pH of the system is adjusted to 8.0, and then the reaction is continued for 3 hours to obtain the product long-chain alkyl bisimidazolin-thiadiazole amide hydroxypropanesulfonate betaine corrosion inhibitor.

[0079] In this embodiment, the solubilizer is methanol, the synergist is potassium iodide, and the surfactant is OP-10.

[0080] In this embodiment, the iron stabilizer is composed of 35% main chelating agent, 25% auxiliary chelating agent, 10% reducing agent, 8% iron stabilizing synergist, and the remainder is water.

[0081] In this embodiment, the main chelating agent is a complex of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and hydroxyethylidene diphosphate (HEDP), which differs from Example 1 in that the mass ratio of the two is 2:1. The auxiliary chelating agent is sodium lignosulfonate, the reducing agent is isoascorbic acid, and the iron stabilizing synergist is glucose and zinc sulfate in a mass ratio of 2:1.

[0082] In this embodiment, the acid solution is hydrochloric acid, and the drainage aid is a mixture of fatty alcohol polyoxyethylene ether, octylphenol polyoxybutylene ether, and sodium dodecyl sulfate in a ratio of 2:1:1.

[0083] In this embodiment, a mixture was prepared by sequentially dissolving 30% acrylamide, 10% cationic monomer, 8% hydrophobic monomer, 12% salt-resistant monomer, and 3% cosolvent in water. After complete dissolution, the pH was adjusted to 7 with sodium hydroxide. Nitrogen gas was introduced while stirring, and a composite initiation system was added at -10°C to initiate the reaction. After cooling to room temperature, the mixture was hydrolyzed, dried, and granulated to obtain an acid thickener.

[0084] In this embodiment, the cationic monomer is methacryloyloxyethyltrimethylammonium chloride; the hydrophobic monomer is a mixture of dimethylallyl-N-alkylammonium chloride and vinyl methacrylate, with a mass ratio of 1:1.8; the salt-resistant monomer is 2-acrylamido-2-methylpropanesulfonic acid (AMPS); the co-solvent is nonylphenol polyoxyethylene ether; and the composite initiation system is a mixture of azobisisobutyronitrile, ammonium persulfate, and sodium bisulfite, with a mass ratio of 1:0.8:1.0.

[0085] Example 3

[0086] This embodiment provides an acid solution system based on the synergistic effect of corrosion inhibitors and iron stabilizers, comprising, by mass percentage:

[0087] 20% acid, 3% composite corrosion inhibitor, 0.5% iron stabilizer, 0.3% drainage aid, 0.6% acid thickener, and the balance is water.

[0088] Its preparation method is as follows:

[0089] Prepare a base acid solution by adding water according to the component dosage. Slowly add the composite corrosion inhibitor to the base acid solution and stir for 30 minutes to fully dissolve the composite corrosion inhibitor. Then add the iron stabilizer and continue stirring for 30-60 minutes. After the iron stabilizer is completely dissolved, add the drainage aid and stir evenly. Finally, add the acid thickener and stir for 30-60 minutes to obtain an acid solution system based on the synergistic effect of the corrosion inhibitor and the iron stabilizer.

[0090] In this embodiment, the composite corrosion inhibitor is composed of 40% slow-release agent, 20% solubilizer, 5% synergist, 2% surfactant, and the remainder is water.

[0091] In this embodiment, the main slow-release agent is an imidazoline derivative corrosion inhibitor, specifically a long-chain alkyl bisimidazoline-thiadiazole amide hydroxypropanesulfonyl betaine corrosion inhibitor, which is prepared by the following steps:

[0092] (1) Diethylenetriamine and oleic acid were added to a four-necked flask equipped with a thermometer, condenser, water separator and stirrer at a molar ratio of 1.2:1. Xylene was added as a water-carrying agent. The mass ratio of reactants to xylene was 1:1. The reaction apparatus was evacuated and filled with nitrogen. The stirring was started and the temperature was gradually increased. The mixture was refluxed at 120°C for 3 hours to separate the water generated by the amidation reaction. The temperature was then gradually increased to 200°C and held for 2 hours to evaporate the water generated by the cyclization reaction. Finally, the reactants were cooled to obtain the imidazoline intermediate.

[0093] (2) In a 10% NaOH aqueous solution, 2,5-dimercaptothiadiazole and sodium chloroacetate were added sequentially at 70℃. The reaction was carried out for 4 hours, cooled, and the pH was adjusted to 3 with dilute hydrochloric acid. The target substance was precipitated, filtered, washed with cold water, dried and purified to obtain 2,5-di(carboxymethylthio)-1,3,4-thiadiazole.

[0094] (3) At 200℃, using phosphorus pentoxide as a dehydrating agent, the imidazoline intermediate obtained in step (1) and the 2,5-bis(carboxymethylthio)-1,3,4-thiadiazole obtained in step (2) were mixed, heated to 180℃, and reacted at a constant temperature for 3h to obtain a long-chain alkyl bisimidazoline-thiadiazole amide corrosion inhibitor.

[0095] (4) The long-chain alkyl bisimidazolin-thiadiazole amide corrosion inhibitor obtained in step (3) above and sodium 3-chloro-2-hydroxybenzenesulfonate are heated to 90°C, the pH of the system is adjusted to 8.0, and then the reaction is continued for 3 hours to obtain the product long-chain alkyl bisimidazolin-thiadiazole amide hydroxypropanesulfonate betaine corrosion inhibitor.

[0096] In this embodiment, the solubilizer is methanol, the synergist is potassium iodide, and the surfactant is OP-10.

[0097] In this embodiment, the iron stabilizer is composed of 35% main chelating agent, 25% auxiliary chelating agent, 10% reducing agent, 8% iron stabilizing synergist, and the remainder is water.

[0098] In this embodiment, the main chelating agent is a complex of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and hydroxyethylidene diphosphate (HEDP), which differs from Example 1 in that the mass ratio of the two is 2:1. The auxiliary chelating agent is sodium lignosulfonate, the reducing agent is isoascorbic acid, and the iron stabilizing synergist is glucose and zinc sulfate in a mass ratio of 2:1.

[0099] In this embodiment, the acid solution is hydrochloric acid, and the drainage aid is a mixture of fatty alcohol polyoxyethylene ether, octylphenol polyoxybutylene ether, and sodium dodecyl sulfate in a ratio of 2:1:1.

[0100] In this embodiment, a mixture was prepared by sequentially dissolving 30% acrylamide, 10% cationic monomer, 8% hydrophobic monomer, 12% salt-resistant monomer, and 3% cosolvent in water. After complete dissolution, the pH was adjusted to 7 with sodium hydroxide. Nitrogen gas was introduced while stirring, and a composite initiation system was added at -10°C to initiate the reaction. After cooling to room temperature, the mixture was hydrolyzed, dried, and granulated to obtain an acid thickener.

[0101] In this embodiment, the cationic monomer is methacryloyloxyethyltrimethylammonium chloride; the hydrophobic monomer is a mixture of dimethylallyl-N-alkylammonium chloride and vinyl methacrylate, with a mass ratio of 1:1.8; the salt-resistant monomer is 2-acrylamido-2-methylpropanesulfonic acid (AMPS); the co-solvent is nonylphenol polyoxyethylene ether; and the composite initiation system is a mixture of azobisisobutyronitrile, ammonium persulfate, and sodium bisulfite, with a mass ratio of 1:0.8:1.0.

[0102] Comparative Example 1

[0103] The composition and preparation method of this comparative example are basically the same as those of Example 1, except that the acid system in the comparative example does not contain an iron stabilizer.

[0104] Specifically, the acid system provided in Comparative Example 1 comprises, by mass percentage: 20% acid, 3% composite corrosion inhibitor, 0.3% drainage aid, 0.6% acid thickener, and the remainder is water.

[0105] Comparative Example 2

[0106] The composition and preparation method of this comparative example are basically the same as those of Example 1. The difference is that the acid system in the comparative example does not contain a composite corrosion inhibitor.

[0107] Specifically, the acid system provided in Comparative Example 2 comprises, by mass percentage: 20% acid, 0.5% iron stabilizer, 0.3% discharge aid, 0.6% acid thickener, and the remainder is water.

[0108] Comparative Example 3

[0109] The composition and preparation method of this comparative example are basically the same as those of Example 1. The difference is that the composite corrosion inhibitor in the comparative example does not contain the synergist KI.

[0110] Specifically, the composite corrosion inhibitor in Comparative Example 3 is composed of 35% slow-release agent, 20% solubilizer, 2% surfactant, and the remainder is water.

[0111] Comparative Example 4

[0112] The comparative example has the same composition and preparation method as Example 1, except that EDTA is used instead of iron stabilizer in the system.

[0113] Specifically, the acid system provided in Comparative Example 4 comprises, by mass percentage: 20% acid, 3% composite corrosion inhibitor, 0.5% EDTA, 0.3% drainage aid, 0.6% acid thickener, and the remainder is water.

[0114] Comparative Example 5

[0115] The composition and preparation method of this comparative example are basically the same as those of Example 1. The difference is that a commercial corrosion inhibitor (Shaanxi Hehe Chemical, a composite imidazoline and pyridine derivative) is used instead of the composite corrosion inhibitor in the system.

[0116] Specifically, the acid system provided in Comparative Example 5 comprises, by mass percentage: 20% acid, 3% a commercial corrosion inhibitor, 0.5% iron stabilizer, 0.3% drainage aid, 0.6% acid thickener, and the remainder is water.

[0117] Performance testing

[0118] (1) Corrosion rate determination

[0119] Referring to section 7.1.2.2 of SYT 5405-2019 "Test Methods and Evaluation of Corrosion Inhibitors for Acidification"—High Temperature and High Pressure Dynamic Corrosion Rate Test Method—corrosion rate tests were conducted on the acid systems in each example and comparative example to test the corrosion inhibition effect of the acid systems. The experimental temperature and rotation speed (60 r / min), experimental pressure, and reaction time were set to 16 MPa and 4 h, respectively, using N8 steel sheets. The corrosion rate was calculated using the following formula:

[0120]

[0121] In the formula: V i —Single-piece corrosion rate, g / (m²) 2 ·h);

[0122] △t — reaction time, h;

[0123] △m i —The corrosion vector of this piece, g;

[0124] A i —Surface area of ​​the piece, mm 2 .

[0125] The corrosion inhibition efficiency is calculated using the following formula:

[0126]

[0127] Where: W1—corrosion rate of metal without corrosion inhibitor;

[0128] W0 — Corrosion rate of metal with added corrosion inhibitor.

[0129] The corrosion rates and corrosion inhibition efficiencies of the acid systems in different embodiments and comparative examples are shown in Table 1. After the experiment, the N80 steel sheet was removed, its surface was dried with nitrogen, and the contact angle of the N80 steel sheet was tested with distilled water. The experimental results are shown in [Table 1]. Figure 2 .

[0130] Table 1. Corrosion inhibition effect of different acid solutions

[0131]

[0132]

[0133] At 140℃ and 160℃, the corrosion inhibition efficiency of the acid systems in Examples 1 to 3 is greater than 92.78%, and at 180℃, the corrosion inhibition efficiency is greater than 87.6%, showing good corrosion inhibition effect and meeting the requirements of on-site construction.

[0134] As can be seen from Example 1, Comparative Example 1, and Comparative Example 4, the corrosion inhibition efficiency is significantly reduced when there is no iron stabilizer or when EDTA is used as an iron stabilizer in the acid system, because there is no synergistic effect with the composite corrosion inhibitor.

[0135] As can be seen from Example 1, Comparative Examples 3 and 5, the corrosion inhibition effect of the acid system without KI and with a certain commercial corrosion inhibitor is significantly lower than that of the present invention.

[0136] Based on this, the results of the hydrophilicity / hydrophobicity determination of the surface of the tested steel sheet are as follows: Figure 2 As shown, the contact angle of the steel sheet without corrosion inhibitor is 67.487°, indicating hydrophilicity. After adding the corrosion inhibitor, the contact angle is greater than 90°, indicating hydrophobicity. Examples 1-3 show contact angles greater than 120.922°, indicating good hydrophobicity. Comparative Examples 1 and 4, due to the synergistic effect of the lack of a system iron stabilizer, have contact angles reduced to 112.221° and 105.315°, respectively. In Comparative Examples 3 and 5, the contact angles in the acid system without KI and with a commercially available corrosion inhibitor decreased to 102.446° and 94.772°, respectively. This indicates that the synergistic effect of the composite corrosion inhibitor and iron stabilizer in the acid system of Examples 1-3 enhances the hydrophobic effect of the steel sheet and improves the corrosion inhibition efficiency.

[0137] (2) Determination of ability to stabilize iron ions

[0138] According to SY / T6571-2012 "Evaluation Method for Performance of Iron Ion Stabilizers for Acidification", by continuously adding iron ion standard solution to the acidic system after gel breaking, and adjusting the pH to between 4.0 and 5.0 with 5% sodium carbonate solution, and maintaining a constant temperature of 140℃, 160℃, and 180℃ for 4 hours, the unstabilized iron ions will precipitate. The ability of the iron stabilizer (iron ion stabilizer) to stabilize iron in different acidic systems in the examples and comparative examples was determined based on the amount of iron ion standard solution used. The test results are shown in Table 2.

[0139] Table 2. Ferric ion stabilization capabilities of different acid solutions

[0140]

[0141]

[0142] Examples 1 to 3 show that the iron ion stabilization capacity of the acid solution system at room temperature, 140°C, and 180°C is greater than 830 mg / L, and can reach up to 925 mg / L, indicating that the acid solution system of the present invention has a good iron ion stabilization capacity.

[0143] As can be seen from Example 1 and Comparative Examples 2, 3, and 5, the ability of the acid systems in Comparative Examples 2, 3, and 5 to stabilize iron ions is significantly reduced when the acid system contains only an iron stabilizer, an acid system using a commercial corrosion inhibitor and an iron stabilizer combined, or an acid system using an inhibitor without KI and an iron stabilizer combined. This is because the acid system has no synergy or poor synergy with the iron stabilizer in the acid system.

[0144] As can be seen from Example 1 and Comparative Example 4, the acidic system using EDTA as an iron stabilizer has a significantly lower ability to stabilize iron ions than that of the present invention.

[0145] (3) Compatibility of acid system

[0146] The compatibility of the acid systems in Examples 1 to 3 was investigated at room temperature and 90°C. The test results are shown in Table 3.

[0147] Table 3 Compatibility of different embodiments

[0148] Example Let stand at room temperature for 24 hours 90℃, let stand for 24 hours Example 1 Homogeneous solution, no stratification, no precipitation Homogeneous solution, no stratification, no precipitation Example 2 Homogeneous solution, no stratification, no precipitation Homogeneous solution, no stratification, no precipitation Example 3 Homogeneous solution, no stratification, no precipitation Homogeneous solution, no stratification, no precipitation

[0149] As can be seen from Table 3, the composite corrosion inhibitor, iron stabilizer and on-site acid, drainage aid and acid thickener in the acid system of the present invention have good compatibility and there is no antagonism between the components, which can ensure the normal use of the acid system.

[0150] 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. An acid solution system based on the synergistic effect of corrosion inhibitors and iron stabilizers, characterized in that, By mass fraction, it includes the following components: The remainder is water.

2. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 1, characterized in that: The composite sustained-release agent comprises the following components by mass fraction:

3. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 2, characterized in that: The main component of the corrosion inhibitor is a long-chain alkyl diimidazoline-thiadiazole amide hydroxypropanesulfonyl betaine corrosion inhibitor, and its preparation method includes the following steps: Step 1: React diethylenetriamine with a carbon chain length of C 11 ~C 18 Long-chain fatty acids were mixed in a molar ratio of 1.2:1, and xylene, a water-carrying agent, was added. The mass ratio of reactants to xylene was 1:0.8-1. After vacuuming, the mixture was stirred and gradually heated to 120°C under a nitrogen atmosphere. The mixture was then refluxed for 1-3 hours to separate the water produced by the reaction. The mixture was then gradually heated to 140°C-200°C and held for 1-2 hours to evaporate the water produced by the cyclization reaction. The mixture was then cooled to obtain the imidazoline intermediate. Step 2: In a 10% NaOH aqueous solution, 2,5-dimercaptothiadiazole and sodium chloroacetate were added sequentially at 55℃~70℃. The reaction was carried out for 3~4 hours, cooled, and the pH was adjusted to 2-3 with dilute hydrochloric acid. The target substance was precipitated, filtered, washed with cold water, and dried to obtain 2,5-bis(carboxymethylthio)-1,3,4-thiadiazole. Step 3: At a temperature of 120℃~200℃, using phosphorus pentoxide as a dehydrating agent, mix the imidazoline intermediate obtained in Step 1 and the 2,5-bis(carboxymethylthio)-1,3,4-thiadiazole obtained in Step 2, and heat to 180℃ for 2~3h to obtain a long-chain alkyl bisimidazoline-thiadiazole amide corrosion inhibitor. Step 4: Heat the long-chain alkyl diimidazoline-thiadiazole amide corrosion inhibitor obtained in Step 3 and sodium 3-chloro-2-hydroxybenzenesulfonate to 80-90℃, adjust the pH of the system to 7.5-8.0, and then continue the reaction for 2-3 hours to obtain the product long-chain alkyl diimidazoline-thiadiazole amide hydroxypropanesulfonate betaine corrosion inhibitor, the structural formula of which is as follows: Where R represents a carbon chain number of C 11 ~C 18 Saturated alkyl group, carbon chain number C 11 ~C 18 The monoalkenyl group has a carbon chain number of C. 11 ~C 18 Any of the diene groups.

4. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 2, characterized in that: The solubilizer is one or more of methanol, ethanol, isopropanol, butanol, n-butanol, isobutanol, ethylene glycol methyl ether, ethylene glycol diethyl ether, and ethylene glycol butyl ether. The synergist is one or more of potassium iodide, cuprous iodide, copper iodide, cuprous chloride, antimony oxide, formamide, antimonyate, propynyl alcohol, ethoxypropynyl alcohol, and propoxypropynyl alcohol. The surfactant is one or more combinations of OP-10, Tween-20, Tween-40, Tween-60, Tween-80, S-20, S-40, S-60, and S-80.

5. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 1, characterized in that: The iron stabilizer comprises the following components by mass fraction:

6. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 5, characterized in that: The main chelating agent is one or more combinations of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphate, ethylenediaminetetraacetic acid and its disodium salt, and citric acid; The co-chelating agent is one or more of sodium lignosulfonate, thiourea, and alkyl mercaptan; The reducing agent is one or more combinations of isoascorbic acid and sodium isoascorbate; The iron-stabilizing synergist is one or more of the following: glucose, sodium gluconate, pregelatinized starch, carboxymethyl starch, maltodextrin, zinc sulfate, zinc chloride, zinc carbonate, basic zinc carbonate, and zinc gluconate.

7. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 6, characterized in that: The main chelating agent is a combination of 2-phosphonobutane-1,2,4-tricarboxylic acid and hydroxyethylidene diphosphate, with a mass ratio of 1 to 4:

1. The co-chelating agent is sodium lignosulfonate; The isoascorbic acid; The iron-stabilizing synergist is a combination of glucose and zinc sulfate, with a mass ratio of 2:

1.

8. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 1, characterized in that: The acid solution is one or a combination of hydrochloric acid and hydrofluoric acid. When the acid solution is a combination of hydrochloric acid and hydrofluoric acid, the volume ratio of hydrochloric acid to hydrofluoric acid is 1 to 4:

1. The drainage aid is one or more combinations of fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene-polyoxypropylene ether, nonylphenol polyoxypropylene ether, octylphenol polyoxybutylene ether, and sodium dodecyl sulfate.

9. The acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 1, characterized in that: The acid thickener, by mass fraction, is prepared from the following component raw materials: The cationic monomer is methacryloyloxyethyltrimethylammonium chloride; the hydrophobic monomer is a mixture of dimethylallyl-N-alkylammonium chloride and vinyl methacrylate, with a mass ratio of 1:1.5 to 2; the salt-resistant monomer is 2-acrylamido-2-methylpropanesulfonic acid; the co-solvent is nonylphenol polyoxyethylene ether; and the initiator is a mixture of azobisisobutyronitrile, ammonium persulfate, and sodium bisulfite, with a mass ratio of 1:0.5 to 1:0.8 to 1.

2. The preparation method of the thickener for acid includes the following steps: Acrylamide was dissolved in water, and cationic monomers, hydrophobic monomers, salt-resistant monomers, and cosolvents were added sequentially to obtain a mixture. After complete dissolution, the pH was adjusted to 7 with sodium hydroxide. Nitrogen gas was introduced while stirring, and a composite initiation system was added at -10℃ to 0℃ to initiate the reaction. After cooling to room temperature, the mixture was hydrolyzed, dried, and granulated to obtain an acid thickener.

10. The method for preparing an acid system based on the synergistic effect of corrosion inhibitor and iron stabilizer according to claim 1, characterized in that, Includes the following steps: Prepare a base acid solution by adding water according to the component dosage. Slowly add the composite corrosion inhibitor to the base acid solution and stir for 30 minutes to fully dissolve the composite corrosion inhibitor. Then add the iron stabilizer and continue stirring for 30-60 minutes. After the iron stabilizer is completely dissolved, add the drainage aid and stir evenly. Finally, add the acid thickener and stir for 30-60 minutes to obtain an acid solution system based on the synergistic effect of the corrosion inhibitor and the iron stabilizer.

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