Corrosion inhibitor for oil and gas field

Abstract

The invention discloses a corrosion inhibitor for oil and gas fields. Benzotriazole, polycarboxylic acid, sodium phosphate, polymaleic anhydride, zinc oxide nanoparticles, chitosan, phytic acid and water are used as main components, the corrosion inhibition performance and stability are remarkably improved through the synergistic effect of the multiple components, a stable protective film can be formed under the high-temperature and high-pressure conditions through the unique component combination, metal corrosion is effectively prevented, and the corrosion inhibition performance is good. The long-term use stability of the corrosion inhibitor is remarkably improved, and a safer and more lasting protection solution is provided for oil and gas field equipment. In addition, due to the addition of natural components such as chitosan and phytic acid, the environmental friendliness of the corrosion inhibitor is enhanced, the negative influence on an ecological system is reduced, and the concept of modern green chemistry is met.

Description

Technical Field

[0001] This invention belongs to the field of corrosion control and protection technology in oil and gas fields, and particularly relates to a novel corrosion inhibitor for oil and gas fields. Background Technology

[0002] With the continued growth of global oil demand and the increasing complexity of oil and gas field extraction environments, corrosion problems in oilfield equipment have become increasingly prominent, posing a key bottleneck to production efficiency and equipment lifespan. To effectively address this challenge, my country mainly employs a comprehensive strategy of physical corrosion protection, chemical corrosion protection, and coating corrosion protection. Among these, chemical corrosion protection technology, with its high economic efficiency and wide range of applications, has become the most commonly used method. By scientifically adding corrosion inhibitors and other chemical substances, this technology can significantly slow down the corrosion process. The corrosion inhibitors react chemically with corrosive media to form a stable protective film, thereby effectively inhibiting the corrosion rate of metals. Simultaneously, injecting scale inhibitors to prevent pipe scaling is also an important strategy for reducing equipment corrosion and extending service life. Based on this, many scholars have actively devoted themselves to the research and development of high-efficiency corrosion inhibitors, striving to provide more efficient and economical solutions for corrosion protection in oil and gas fields, and contributing to the sustainable development of the petroleum industry.

[0003] Lü Na [1] She focuses on research into circulating cooling water commonly used in the petroleum industry. During long-term operation, circulating cooling water faces problems such as inorganic salt precipitation, corrosion, and algal growth, causing damage to equipment and severely impacting its normal operation. Through detailed research, she discovered that composite pyridine quaternary ammonium salts, after compounding, exhibit particularly significant corrosion inhibition effects in high-temperature, concentrated acid environments, with corrosion rates far below the industry's first-class standard. Based on this discovery, she successfully synthesized a novel corrosion inhibitor containing 2,6-di-tert-butylphenol using innovative raw materials such as quaternized boric acid and modified graphene oxide. The ingenious synergistic effect of quaternized boric acid and modified graphene oxide significantly enhances the corrosion inhibition effect of this composite corrosion inhibitor, increasing the corrosion inhibition rate by over 10%, providing an efficient technical solution to the corrosion problems caused by circulating cooling water.

[0004] Li Li, Qiao Shaoke [2]Researchers have conducted in-depth research on highly efficient acid fracturing corrosion inhibitors to address the severe corrosion of well tubing and downhole metal equipment after acid fracturing. They have successfully developed a composite imidazoline quaternary ammonium salt corrosion inhibitor suitable for oil and gas wells, gathering and transportation systems, and water injection processes in oilfields. This corrosion inhibitor is simple to prepare, requiring only proportional mixing followed by degassing. No special equipment is needed, resulting in low initial investment, low energy consumption, high production efficiency and product qualification rate, reduced labor intensity, and minimal environmental impact, making it ideal for continuous large-scale production. Furthermore, this acid fracturing corrosion inhibitor achieves significant corrosion inhibition with low dosage through the synergistic effect of its components. It also exhibits excellent high-temperature resistance, high cost-effectiveness, and safe and environmentally friendly use, providing a cost-effective solution for corrosion protection in oilfields.

[0005] Ma Yunsheng, Zhao Liqiu [3] Researchers investigating scaling and corrosion problems in marine storage tanks found that while commonly used polyaspartic acid (PASP) can inhibit scale and form a protective film to suppress corrosion, its single functional group means its scale inhibition effect weakens with changes in the seawater environment, and its corrosion inhibition performance is also insufficient. Therefore, they developed a novel corrosion inhibitor for tank walls in alkaline liquid environments, using modified polyaspartic acid as the main agent, supplemented with sodium tungstate, thiourea, and other components. This inhibitor exhibits a good synergistic effect in alkaline liquid environments, possessing excellent scale inhibition and dispersing properties and long-lasting corrosion inhibition performance, effectively meeting the diverse needs of marine storage tanks.

[0006] Zhou Yongsheng [4] This research delved into the corrosion problems of acid on surface equipment and downhole pipe strings after acidizing operations, focusing on the development of low-temperature acidizing corrosion inhibitors. Addressing the current market situation where high-temperature and medium-temperature corrosion inhibitors formulated with alcohol as a solvent have poor compatibility with acid systems and significantly increased costs, as well as the problem of nitrogen- and sulfur-containing compounds easily forming flocculent precipitates and unsatisfactory corrosion inhibition effects in low-temperature corrosion inhibitor applications, a low-temperature acidizing corrosion inhibitor suitable for the petroleum industry was successfully developed. This inhibitor uses linolenic acid, hydroxyethylenediamine, and dichlorohexane as key raw materials, forming a robust corrosion-inhibiting film on the metal surface through chemical adsorption, effectively blocking acid corrosion. Simultaneously, potassium chromate, sodium silicate, and potassium iodide are used as auxiliary agents to form an insoluble oxide film through physical adsorption, further strengthening metal protection. In addition, the careful formulation of various agents such as alkynyl alcohol, emulsifiers, and mercaptoacetic acid ensures the excellent storage stability of this corrosion inhibitor in acid. When its mass percentage is 0.08%, the corrosion inhibition rate can reach up to 99.12%, showing a significant corrosion inhibition effect and providing an efficient solution for equipment protection in acidizing operations in the petroleum industry.

[0007] An Shiyu and Rui Yulan [5]To address the severe corrosion problem of pipelines after acidification, a novel corrosion inhibitor, lauric acid imidazoline quaternary ammonium salt, was successfully synthesized using lauric acid, diethylenetriamine, and benzyl chloride as raw materials. To further enhance the corrosion inhibition effect, thiourea compounds were selected as compounding agents, and the inhibitor was carefully formulated. Through static corrosion weight loss experiments, they found that among the four corrosion inhibitors—lauric acid imidazoline quaternary ammonium salt, thiourea, aminothiourea, and thiourea dioxide—lauric acid imidazoline quaternary ammonium salt exhibited superior corrosion inhibition performance in saline and CO2-containing environments. In the binary compound formulation, the synergistic effect of lauric acid imidazoline quaternary ammonium salt and thiourea dioxide was the most significant, resulting in the best corrosion inhibition performance. Particularly when the mass ratio of the two was 1:2, the corrosion inhibition rate reached as high as 85.30%. Furthermore, the AC impedance test results were consistent with the static corrosion weight loss experiment results, further verifying the superiority of this compound formulation. When imidazoline quaternary ammonium salt of laurate and thiourea dioxide are compounded at a mass ratio of 1:2, the corrosion inhibition rate reaches 86.68%, which is a significant effect.

[0008] Over the years, domestic and international scholars have conducted extensive research on corrosion inhibitors for oil and gas fields. However, as oil and gas well development enters its later stages and various production enhancement technologies are applied, corrosion within oil and gas wells faces greater challenges, and the following problems still exist: (1) With the changes in the environment of oil and gas fields, such as rising temperature and pH, most corrosion inhibitors currently have limitations. They can only alleviate corrosion in specific environments. Once the environment in the oil and gas well changes, their effectiveness will be greatly reduced, increasing the risk of severe corrosion of downhole equipment. In this case, it is necessary to re-develop and add other corrosion inhibitors, which greatly increases the cost of oil and gas field development and affects the efficiency of oil and gas field development.

[0009] (2) Currently, some corrosion inhibitors still rely on traditional oil-based formulations, with methanol, ethanol, and ethyl acetate as their main solvents. While these solvents can effectively inhibit metal corrosion and provide antioxidant properties to a certain extent, thus extending the service life of metal materials, their chemical properties also present significant challenges. As volatile organic compounds, these solvents are highly volatile and flammable, leading to significant fire and explosion hazards during storage, transportation, and actual operation. In addition, these solvents themselves are toxic, and long-term contact or inhalation may pose a potential threat to human health, causing various health problems. Moreover, the protective effect of these corrosion inhibitors may not remain stable when facing harsh corrosive environments (such as high sulfur, high salt, or strong acid conditions). Especially under high temperature and high pressure conditions, the accelerated evaporation of solvents reduces the concentration of corrosion inhibitors, further weakening their protective performance.

[0010] [1] Lü Na. A corrosion inhibitor containing 2,6-di-tert-butylphenol and its preparation method. CN 118516676 A; [2] Li Li, Qiao Shaoke, Li Long, et al. An acidizing corrosion inhibitor for fracturing oil and gas wells and its preparation method. CN118755468 A; [3] Ma Yunsheng, Zhao Liqiu, Wei Shengke, et al. A corrosion inhibitor for tank walls in alkaline liquid environments and its preparation method. CN 118756144 A; [4] Zhou Yongsheng. A low-temperature acidification corrosion inhibitor for petroleum and its preparation method. CN 118755462 A; [5] An Shiyu, Rui Yulan. Corrosion inhibition performance of imidazoline quaternary ammonium salt of lauric acid and its composite corrosion inhibitor [J]. Guangzhou Chemical Industry, 2024, 52(19):61-64. Summary of the Invention

[0011] This invention addresses the aforementioned problems by improving corrosion inhibitors. It designs an oil and gas field corrosion inhibitor with benzotriazole, polycarboxylic acid, sodium phosphate, polymaleic anhydride, zinc oxide nanoparticles, chitosan, phytic acid, and water as its main components. Through the synergistic effect of its multiple components, it significantly improves corrosion inhibition performance and stability, solving the problem of insufficient protection by traditional corrosion inhibitors in highly corrosive environments. Traditional oil-based corrosion inhibitors may fail under high sulfur, high salinity, or strong acid conditions and pose risks of flammability, explosiveness, and toxicity. This novel corrosion inhibitor, with its water-based formulation, significantly reduces these risks while maintaining excellent corrosion inhibition. Its unique component combination can form a stable protective film under high temperature and high pressure conditions, effectively preventing metal corrosion and significantly improving the long-term stability of the corrosion inhibitor, providing a safer and more durable protection solution for oil and gas field equipment. Furthermore, the addition of natural components such as chitosan and phytic acid enhances the environmental friendliness of the corrosion inhibitor, reducing negative impacts on the ecosystem and aligning with the principles of modern green chemistry.

[0012] The technical solution adopted in this invention is as follows: A corrosion inhibitor for oil and gas fields comprises the following components by mass percentage: Benzotriazole 4-6% Polycarboxylate 9~11% Sodium phosphate 4~6% Polymaleic anhydride 7-9% Zinc oxide nanoparticles 1~3% Chitosan 2-4% Phytic acid 1~3% Water balance.

[0013] The total mass percentage of polymaleic anhydride, zinc oxide nanoparticles, and chitosan is 10-17%, preferably 13-17%; the mass ratio of zinc oxide nanoparticles to chitosan is 1-1.5:2, preferably 1.3-1.5:2.

[0014] The molecular weight of the polycarboxylic acid is between 6000 and 10000 g / mol.

[0015] The molecular weight of the polymaleic anhydride is between 800 and 2000 g / mol.

[0016] The zinc oxide nanoparticles have a diameter between 20-100 nm.

[0017] This invention further provides a method for preparing the above-mentioned corrosion inhibitor for oil and gas fields, which is carried out according to the following steps: Step 1: Dissolve the polymer. Since polycarboxylic acid and polymaleic anhydride have poor solubility at room temperature, take a portion of water, heat it to 60-70℃, and add polycarboxylic acid and polymaleic anhydride to it in sequence, stirring until completely dissolved. This solution is called solution A.

[0018] Step 2: Dissolve benzotriazole. Take a portion of water, heat it to 60-70℃, add benzotriazole, and stir until completely dissolved. After it and solution A have cooled to 35-40℃, prepare a compound solution, which is called solution B.

[0019] Step 3: Add inorganic salts. Add sodium phosphate to solution B and stir until completely dissolved. This solution is called solution C.

[0020] Step 4: Disperse the nanoparticles. After solution C has completely cooled, add the zinc oxide nanoparticles to solution C and disperse them for 20-30 minutes using an ultrasonic disperser to ensure uniform dispersion of the nanoparticles. This solution is called solution D.

[0021] Step 5: Dissolve the natural polymer. Add chitosan and phytic acid to solution D and stir until completely dissolved. This solution is called solution E.

[0022] Step 6: Adjust the pH value. Use dilute acid or dilute alkali to adjust the pH value of the corrosion inhibitor to about 7-9. Add the remaining water according to the total mass of the formula, stir well, and the desired new corrosion inhibitor is obtained.

[0023] This invention uses benzotriazole, polycarboxylic acid, sodium phosphate, polymaleic anhydride, zinc oxide nanoparticles, chitosan, phytic acid, and water as the main corrosion-inhibiting components, aiming to maximize their corrosion-inhibiting effect while ensuring environmental friendliness. Benzotriazole exhibits excellent metal surface adsorption capacity, particularly for copper and copper alloys, demonstrating significant corrosion inhibition. Polycarboxylic acid and polymaleic anhydride form stable complexes with metal ions through chelation, effectively preventing scaling and thus delaying corrosion. Sodium phosphate reacts with metals in acidic environments to form a phosphate protective film, providing additional protection. Zinc oxide nanoparticles, utilizing their high specific surface area and activity, rapidly form a dense oxide film on the metal surface, enhancing physical protection. Chitosan and phytic acid, as natural polymers, form a protective film through chemisorption, exhibiting both biocompatibility and environmental friendliness.

[0024] These components, through scientific formulation, exhibit excellent multifunctionality. They provide comprehensive protection under high temperature, high pressure, high salinity, and acid-base environments, meeting the complex and ever-changing needs of oil and gas fields. The synergistic effect between different corrosion-inhibiting components significantly enhances the overall corrosion inhibition performance. For example, chitosan has good biocompatibility and adsorption capacity, effectively adsorbing onto metal surfaces to form a protective film and prevent metal corrosion; phytic acid has strong chelating ability, forming stable complexes with metal ions; the formulation of chitosan with polycarboxylic acid and phytic acid not only improves the corrosion inhibition effect but also enhances solution stability. Zinc oxide nanoparticles can form a physical protective layer on the metal surface, enhancing the corrosion inhibition effect, while also possessing good conductivity and stability. This not only improves the performance of corrosion inhibitors but also opens up new directions for corrosion inhibitor research and development.

[0025] By optimizing the proportions and formulation of its components, this corrosion inhibitor not only exhibits excellent corrosion inhibition but also demonstrates good dispersibility, stability, and environmental friendliness. This comprehensive performance improvement makes the corrosion inhibitor more widely applicable and of greater value in complex oil and gas field environments.

[0026] The corrosion inhibitor provided by this invention uses common and low-cost raw materials, has a simple formulation process, and is easy to apply, store, and transport on-site, significantly reducing production costs. Furthermore, the use of natural polymers not only improves the environmental friendliness of the inhibitor but also increases its biodegradability, ensuring that it will not cause long-term environmental pollution after use. Compared to traditional oil-based corrosion inhibitors, the water-based inhibitor has lower toxicity, better environmental compatibility, and reduces negative impacts on the ecosystem. This corrosion inhibitor possesses excellent corrosion inhibition performance, multifunctionality, economic benefits, and environmental friendliness, providing an efficient and reliable solution for the protection of oil and gas field equipment. Detailed Implementation

[0027] The present invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of the present invention. Example 1

[0028] Prepare the materials and weigh each component according to the following proportions: 4 parts by mass of benzotriazole, 9 parts by mass of polycarboxylic acid, 4 parts by mass of sodium phosphate, 7 parts by mass of polymaleic anhydride, 1 part by mass of zinc oxide nanoparticles, 2 parts by mass of chitosan, 1 part by mass of phytic acid, and 72 parts by mass of water. Take 30 parts by mass of water and heat to 60°C. Add the polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water and heat to 65°C. Add the benzotriazole and stir until completely dissolved. After both Solution A and Solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add the sodium phosphate to Solution B and stir until completely dissolved. This is labeled Solution C. After Solution C has completely cooled, add the zinc oxide nanoparticles to Solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add the chitosan and phytic acid to Solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 32 parts by weight of water, stir well, and the desired new corrosion inhibitor is obtained. Example 2

[0029] Prepare the materials and weigh each component according to the following proportions: 6 parts by mass of benzotriazole, 11 parts by mass of polycarboxylic acid, 6 parts by mass of sodium phosphate, 9 parts by mass of polymaleic anhydride, 3 parts by mass of zinc oxide nanoparticles, 4 parts by mass of chitosan, 3 parts by mass of phytic acid, and 58 parts by mass of water. Take 30 parts by mass of water, heat to 60°C, and add polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water, heat to 65°C, add benzotriazole, and stir until completely dissolved. After both solution A and solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add sodium phosphate to solution B and stir until completely dissolved. This is labeled Solution C. After solution C has completely cooled, add zinc oxide nanoparticles to solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add chitosan and phytic acid to solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 18 parts by weight of water, stir well, and the desired new corrosion inhibitor is obtained. Example 3

[0030] Prepare the materials and weigh each component according to the following proportions: 5 parts by mass of benzotriazole, 10 parts by mass of polycarboxylic acid, 5 parts by mass of sodium phosphate, 8 parts by mass of polymaleic anhydride, 2 parts by mass of zinc oxide nanoparticles, 3 parts by mass of chitosan, 2 parts by mass of phytic acid, and 65 parts by mass of water. Take 30 parts by mass of water, heat to 60°C, and add polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled as solution A. Take 10 parts by mass of water, heat to 65°C, add benzotriazole, and stir until completely dissolved. After both solution A and benzotriazole have cooled to 40°C, reconstitute the solution. This is labeled as solution B. Add sodium phosphate to solution B and stir until completely dissolved. This is labeled as solution C. After solution C has completely cooled, add zinc oxide nanoparticles to solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled as solution D. Add chitosan and phytic acid to solution D and stir until completely dissolved. This is labeled as solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 25 parts by weight of water, stir well, and the desired new corrosion inhibitor is obtained. Example 4

[0031] Prepare the materials and weigh each component according to the following proportions: 4 parts by mass of benzotriazole, 10 parts by mass of polycarboxylic acid, 5 parts by mass of sodium phosphate, 7 parts by mass of polymaleic anhydride, 1 part by mass of zinc oxide nanoparticles, 2 parts by mass of chitosan, 2 parts by mass of phytic acid, and 69 parts by mass of water. Take 30 parts by mass of water and heat to 60°C. Add the polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water and heat to 65°C. Add the benzotriazole and stir until completely dissolved. After both Solution A and Solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add the sodium phosphate to Solution B and stir until completely dissolved. This is labeled Solution C. After Solution C has completely cooled, add the zinc oxide nanoparticles to Solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add the chitosan and phytic acid to Solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 29 parts by weight of water, stir well, and the desired new corrosion inhibitor is obtained. Example 5

[0032] Prepare the materials and weigh each component according to the following proportions: 5 parts by mass of benzotriazole, 10 parts by mass of polycarboxylic acid, 5 parts by mass of sodium phosphate, 5 parts by mass of polymaleic anhydride, 2 parts by mass of zinc oxide nanoparticles, 3 parts by mass of chitosan, 2 parts by mass of phytic acid, and 68 parts by mass of water. Take 30 parts by mass of water and heat to 60°C. Add the polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water and heat to 65°C. Add the benzotriazole and stir until completely dissolved. After both Solution A and Solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add the sodium phosphate to Solution B and stir until completely dissolved. This is labeled Solution C. After Solution C has completely cooled, add the zinc oxide nanoparticles to Solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add the chitosan and phytic acid to Solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 28 parts by weight of water, stir well, and the desired new corrosion inhibitor is obtained. Example 6

[0033] Prepare the materials and weigh each component according to the following proportions: 5 parts by mass of benzotriazole, 10 parts by mass of polycarboxylic acid, 5 parts by mass of sodium phosphate, 8 parts by mass of polymaleic anhydride, 2 parts by mass of zinc oxide nanoparticles, 1 part by mass of chitosan, 2 parts by mass of phytic acid, and 67 parts by mass of water. Take 30 parts by mass of water and heat to 60°C. Add the polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water and heat to 65°C. Add the benzotriazole and stir until completely dissolved. After both Solution A and Solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add the sodium phosphate to Solution B and stir until completely dissolved. This is labeled Solution C. After Solution C has completely cooled, add the zinc oxide nanoparticles to Solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add the chitosan and phytic acid to Solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 27 parts by weight of water, stir well, and the desired new corrosion inhibitor is obtained. Example 7

[0034] Prepare the materials and weigh each component according to the following proportions: 5 parts by mass of benzotriazole, 10 parts by mass of polycarboxylic acid, 5 parts by mass of sodium phosphate, 8 parts by mass of polymaleic anhydride, 5 parts by mass of zinc oxide nanoparticles, 3 parts by mass of chitosan, 2 parts by mass of phytic acid, and 62 parts by mass of water. Take 30 parts by mass of water and heat to 60°C. Add the polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water and heat to 65°C. Add the benzotriazole and stir until completely dissolved. After both Solution A and Solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add the sodium phosphate to Solution B and stir until completely dissolved. This is labeled Solution C. After Solution C has completely cooled, add the zinc oxide nanoparticles to Solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add the chitosan and phytic acid to Solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 22 parts by weight of water, stir well, and the desired new corrosion inhibitor is obtained. Comparative Example 1

[0035] Prepare the materials and weigh each component according to the following proportions: 5 parts by mass of benzotriazole, 10 parts by mass of polycarboxylic acid, 5 parts by mass of sodium phosphate, 8 parts by mass of polymaleic anhydride, 3 parts by mass of chitosan, 2 parts by mass of phytic acid, and 67 parts by mass of water. Take 30 parts by mass of water and heat to 60°C. Add the polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water and heat to 65°C. Add the benzotriazole and stir until completely dissolved. After both Solution A and Solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add the sodium phosphate to Solution B and stir until completely dissolved. This is labeled Solution C. After Solution C has completely cooled, add the zinc oxide nanoparticles to Solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add the chitosan and phytic acid to Solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 25 parts water, stir well, and the desired new corrosion inhibitor is obtained. Comparative Example 2

[0036] Prepare the materials and weigh each component according to the following proportions: 5 parts by mass of benzotriazole, 10 parts by mass of polycarboxylic acid, 5 parts by mass of sodium phosphate, 8 parts by mass of polymaleic anhydride, 2 parts by mass of zinc oxide nanoparticles, and 70 parts by mass of water. Take 30 parts by mass of water and heat to 60°C. Add the polycarboxylic acid and polymaleic anhydride sequentially, stirring until completely dissolved. This is labeled Solution A. Take 10 parts by mass of water and heat to 65°C. Add the benzotriazole and stir until completely dissolved. After both Solution A and Solution B have cooled to 40°C, reconstitute the solution. This is labeled Solution B. Add the sodium phosphate to Solution B and stir until completely dissolved. This is labeled Solution C. After Solution C has completely cooled, add the zinc oxide nanoparticles to Solution C and disperse using an ultrasonic disperser for 20 minutes to ensure uniform dispersion of the nanoparticles. This is labeled Solution D. Add the chitosan and phytic acid to Solution D and stir until completely dissolved. This is labeled Solution E. Adjust the pH of the corrosion inhibitor to around 7-9 using dilute acid or dilute alkali, add the remaining 22% water, stir well, and the desired new corrosion inhibitor is obtained.

[0037] Corrosion inhibitors were prepared according to the specific embodiments 1-7 and comparative examples 1 and 2, respectively, and designated as corrosion inhibitors 1-7, comparative corrosion inhibitor 1, and comparative corrosion inhibitor 2. The corrosion inhibition rate of the corrosion-resistant plates was tested using the weight loss method, and nine sets of control experiments were conducted for each of the nine corrosion inhibitors. In the experiments, all corrosion-resistant plates were suspended in 200 mL of simulated formation water. Each control experiment consisted of a blank group and a corrosion-inhibited group; 2 mL of the corresponding corrosion inhibitor was added to each corrosion-inhibited group, for a total of 18 experiments. The experimental results are shown in the table below.

[0038] Table 1 Corrosion inhibition rate of different corrosion inhibitors Experimental samples Corrosion inhibition rate / % Corrosion inhibitor 1 87.9 Corrosion inhibitor 2 89.2 Corrosion inhibitor 3 90.1 Corrosion inhibitor 4 88.6 Corrosion inhibitor 5 79.1 Corrosion inhibitor 6 81.1 Corrosion inhibitor 7 78.5 Comparison of corrosion inhibitor 1 82.1 Comparison of corrosion inhibitor 2 80.7 As shown in the table above, corrosion inhibitor 3 exhibits the best corrosion inhibition effect, reaching 90.1%. Comparing it with corrosion inhibitor 1, it can be observed that the absence of zinc oxide nanoparticles leads to more severe localized corrosion of the substrate and a decrease in overall corrosion inhibition effect. The lack of zinc oxide nanoparticles weakens the physical barrier effect, causes cathodic protection failure, and reduces synergistic passivation capabilities. Comparing it with corrosion inhibitor 2, it can be observed that the absence of chitosan and phytic acid results in more severe corrosion of the substrate and a more significant decrease in corrosion inhibition effect. The absence of chitosan and phytic acid degrades the film-forming properties of the corrosion inhibitor, simplifies the corrosion inhibition mechanism, and reduces its environmental adaptability.

[0039] Next, the concentration of corrosion inhibitor 3 was optimized by diluting it with water. The mass percentage concentration of the original corrosion inhibitor 3 solution was 0.5-3%. The experimental results are shown in the table below.

[0040] Table 2 Corrosion inhibition rate of corrosion inhibitor 3 at different concentrations concentration / % Corrosion inhibition rate / % 0.5 91.8 1 90.1 1.5 90.5 2 89.8 2.5 89.5 3 89.3 As shown in the table above, corrosion inhibitor 3 with a concentration of 0.5% has the best corrosion inhibition effect, reaching 91.8%.

[0041] This invention innovatively incorporates zinc oxide nanoparticles, chitosan, and phytic acid, forming a multi-component synergistic effect with key corrosion inhibitors such as benzotriazole. The application of nanotechnology and the utilization of natural polymers enhance the overall performance of the corrosion inhibitor. Furthermore, combined with the invention's unique formulation method, economic efficiency, and cost-effectiveness, it provides a completely new solution for corrosion protection of oil and gas field equipment.

[0042] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A corrosion inhibitor for oil and gas fields, characterized in that, It includes the following components by mass percentage: Benzotriazole 4-6% Polycarboxylate 9~11% Sodium phosphate 4~6% Polymaleic anhydride 7-9% Zinc oxide nanoparticles 1~3% Chitosan 2-4% Phytic acid 1~3% Water balance.

2. The corrosion inhibitor for oil and gas fields according to claim 1, characterized in that, The total mass percentage of polymaleic anhydride, zinc oxide nanoparticles, and chitosan is 10-17%.

3. The corrosion inhibitor for oil and gas fields according to claim 2, characterized in that, The total mass percentage of polymaleic anhydride, zinc oxide nanoparticles, and chitosan is 13-17%.

4. The corrosion inhibitor for oil and gas fields according to claim 1, characterized in that, The mass ratio of zinc oxide nanoparticles to chitosan is 1~1.5:

2.

5. The corrosion inhibitor for oil and gas fields according to claim 1, characterized in that, The mass ratio of zinc oxide nanoparticles to chitosan is 1.3~1.5:

2.

6. The corrosion inhibitor for oil and gas fields according to claim 1, characterized in that, The polycarboxylic acid has a molecular weight between 6000-10000 g / mol; the polymaleic anhydride has a molecular weight between 800-2000 g / mol; and the zinc oxide nanoparticles have a diameter between 20-100 nm.

7. The method for preparing the corrosion inhibitor for oil and gas fields according to claim 1, characterized in that, Includes the following steps: Step 1: Take a portion of water and heat it to 60-70℃. Add polycarboxylic acid and polymaleic anhydride to it in sequence, stir until completely dissolved, and cool it to room temperature to 35-40℃. This solution is called solution A. Step 2: Take another portion of water and heat it to 60-70℃. Add benzotriazole and stir until completely dissolved. Cool it to room temperature (35-40℃) and mix it with solution A. This solution is called solution B. Step 3: Add sodium phosphate to solution B and stir until completely dissolved. This solution is called solution C. Step 4: After solution C has completely cooled, uniformly disperse the zinc oxide nanoparticles in solution C, and denote this as solution D; Step 5: Add chitosan and phytic acid to solution D and stir until completely dissolved. This solution is called solution E. Step 6: Adjust the pH of the solution to 7-9, add the remaining water, stir well, and you have the product.

8. The application of the corrosion inhibitor for oil and gas fields according to claim 1, characterized in that, The corrosion inhibitor is used after being diluted with water, and the mass concentration of the corrosion inhibitor is 0.5-3%.