A method for manufacturing a solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for seawater oil well pipelines

Abstract

This invention relates to the field of anti-corrosion reagent technology, specifically disclosing a method for manufacturing a solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for seawater oil well pipelines. The agent comprises a three-layer core-shell structure: the core layer is composed of a copolymer hydrogel of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam, loaded with sodium isoascorbate and a copper-L-histidine complex; the middle layer is composed of 3-aminophenylboronic acid-functionalized silica nanoparticles and catechol linked by dynamic borate ester bonds; and the shell layer is composed of a copolymer of 3,4-dihydroxyphenylalanine and 1H,1H,2H,2H-perfluorodecyl acrylate coating a corrosion-inhibiting and bactericidal complex. This invention overcomes the pH conflict between oxygen removers and corrosion inhibitors in traditional reagents through the synergistic effect of the core-shell structure and dynamic bonds, achieving integrated functions of oxygen removal, bactericidal action, corrosion inhibition, and scale inhibition. It effectively inhibits microbial corrosion, reduces the risk of scaling, extends the lifespan of seawater pipelines, and is suitable for complex marine conditions.

Description

Technical Field

[0001] This invention belongs to the field of anti-corrosion reagent technology, specifically relating to a method for manufacturing a solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for seawater oil well pipelines. Background Technology

[0002] During long-term operation, seawater pipelines are susceptible to corrosion from a combination of factors, leading to a series of destructive phenomena. Seawater contains a large amount of dissolved oxygen, which reacts chemically with the pipeline metal (such as carbon steel and cast iron), causing the inner wall to gradually rust and thin. Simultaneously, microorganisms in seawater (such as sulfate-reducing bacteria and iron bacteria) form a slippery biofilm on the pipeline surface. The acidic substances and hydrogen sulfide produced by their metabolism further exacerbate metal corrosion, forming localized pits or even pinholes. Furthermore, the high concentration of chloride ions in seawater can penetrate the protective film on the metal surface, accelerating the oxidation and dissolution of the pipeline. Calcium and magnesium ions in seawater also form deposits, causing under-deposit corrosion and pipeline blockage. These combined problems lead to decreased pipeline pressure resistance, reduced water transport efficiency, and in severe cases, leaks, increasing maintenance and replacement costs and potentially causing safety hazards such as seawater pollution.

[0003] To mitigate corrosion in seawater pipelines, the industry typically employs multifunctional chemical reagents for protection. These reagents must simultaneously address damage caused by oxidation, microorganisms, and chloride ions. Traditionally, these reagents generally contain three core components: first, oxygen scavengers, such as nitrites, which react with dissolved oxygen in seawater to reduce oxidation of metals; second, corrosion inhibitors, like imidazoline compounds, which form a protective film on the metal surface, blocking corrosive substances such as chloride ions; third, bactericides, such as quaternary ammonium salts, used to kill microorganisms in seawater and prevent biofilm formation; and fourth, scale inhibitors, such as organophosphonates, which inhibit the growth of calcium carbonate crystals. These components are mixed to form solid or liquid reagents, which are periodically added to the pipelines to provide comprehensive protection.

[0004] However, there are significant contradictions in the composition design of composite reagents in the existing technology: on the one hand, nitrite-based oxygen scavengers need to be stable and efficient in an alkaline environment with pH > 9; on the other hand, imidazoline-based slow-release agents...

[0005] Corrosion inhibitors undergo molecular hydrolysis at pH > 8.5, significantly reducing their ability to form a protective film on metal surfaces. Because existing solid composite reagents cannot physically isolate the interaction environments of these two components, a compromise must be made regarding the overall pH of the system (typically between 8.5 and 9). Within this pH range, the oxygen removal efficiency of nitrites decreases drastically (due to insufficient alkalinity), while the stability of imidazoline cannot be guaranteed (due to excessive alkalinity), ultimately leading to large fluctuations in corrosion inhibition rates and unstable protective effects. Furthermore, scale inhibitors (such as organophosphonates) precipitate with calcium ions under alkaline conditions, exacerbating scaling. These contradictions directly limit the reliable application of composite reagents in long-term corrosion protection of seawater pipelines. Summary of the Invention

[0006] The purpose of this invention is to provide a method for manufacturing a solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for seawater oil well pipelines, so as to solve the problems mentioned in the background art.

[0007] The first aspect of the present invention provides a solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for use in seawater oil well pipelines.

[0008] Specifically, a solid oxygen-scavenging, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for seawater oil well pipelines comprises a three-layer core-shell structure:

[0009] Core layer: Composed of a copolymer hydrogel of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam, wherein the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam in the copolymer hydrogel is 2.8-3.2:1, and loaded with sodium isoascorbate and a copper-L-histidine complex, wherein the copper-L-histidine complex accounts for 5-15% of the mass of sodium isoascorbate;

[0010] Intermediate layer: composed of 3-aminophenylboronic acid functionalized silica nanoparticles and catechol linked by dynamic borate ester bonds, wherein the molar ratio of 3-aminophenylboronic acid to catechol is 1:0.95-1.05, and the particle size of silica nanoparticles is 45-55 nm.

[0011] Shell: Composed of a corrosion-inhibiting and bactericidal complex coated with a copolymer of 3,4-dihydroxyphenylalanine and 1H,1H,2H,2H-perfluorodecyl acrylate, wherein the molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate is 4.0-4.2:1. The corrosion-inhibiting and bactericidal complex includes imidazoline corrosion inhibitor, hexadecyltrimethylammonium bromide and sodium tungstate, and the mass ratio of imidazoline to hexadecyltrimethylammonium bromide is 4.0-4.2:1, and sodium tungstate accounts for 12% of the mass of the corrosion-inhibiting and bactericidal complex.

[0012] Preferably, the crosslinking agent of the core layer copolymer hydrogel is N,N'-methylenebisacrylamide, and the amount used is 0.8-1.5% of the total mass of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam.

[0013] Preferably, the buffering capacity of the intermediate dynamic borate ester bond in the pH 8.0-8.5 range is 0.14-0.16 mol / pH.

[0014] Preferably, the 3,4-dihydroxyphenylalanine-1H,1H,2H,2H-perfluorodecyl acrylate copolymer of the shell layer has a swelling rate of 55-70% and a porosity of >20% at pH ≥ 8.5.

[0015] A second aspect of the present invention provides a method for manufacturing a solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for seawater oil well pipelines.

[0016] Specifically, a method for manufacturing a solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agent for seawater oil well pipelines includes the following steps:

[0017] A. Core layer preparation:

[0018] A1: 2-Acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam were dissolved in deionized water at a molar ratio of 2.8-3.2:1. N,N'-methylenebisacrylamide crosslinking agent and ammonium persulfate initiator were added. The mixture was reacted at 60°C under nitrogen protection for 24 hours to form hydrogel microspheres.

[0019] A2: Microspheres were immersed in a solution containing sodium isoascorbate and a copper-L-histidine complex, and then vacuum dried to obtain a core layer loaded with an oxygen scavenger;

[0020] B. Intermediate layer embellishment:

[0021] B1: Disperse silica nanoparticles in ethanol, add 3-aminopropyltriethoxysilane, and reflux at 70-80℃ for 4-6 hours to obtain aminated SiO2.

[0022] B2: Aminated SiO2 is reacted with 3-aminophenylboronic acid under acidic conditions (pH≈4.5) and in an aqueous ethanol solvent, followed by the addition of catechol, and the reaction is carried out at 30°C for 2-3 hours to form a dynamic buffer layer.

[0023] C. Shell covering:

[0024] C1: 3,4-Dihydroxyphenylalanine and 1H,1H,2H,2H-perfluorodecyl acrylate were dissolved in Tris-HCl buffer at pH 8.5 at a molar ratio of 4.0-4.2:1. Ammonium persulfate was added, and polymerization was carried out at 60°C under nitrogen protection for 3-5 hours to obtain a copolymer solution.

[0025] C2: Imidazoline, hexadecyltrimethylammonium bromide, and sodium tungstate are mixed in proportion and sprayed together with the copolymer solution onto the surface of the intermediate layer. The mixture is then cured at 70°C for 12 hours to form a shell layer.

[0026] Preferably, in step A1, the amount of ammonium persulfate is 0.8-1.2% of the total mass of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam.

[0027] Preferably, in step B2, the molar ratio of 3-aminophenylboronic acid to catechol is 1:1, and the reaction temperature is 30°C.

[0028] Preferably, the spray pressure in C2 is 0.25-0.35 MPa and the curing temperature is 70°C.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] (1) The dynamic borate ester bond in the intermediate layer has a precise pH buffering capacity (buffer capacity up to 0.15 mol / pH). It can reversibly dissociate and bind hydrogen ions to stably maintain the partitioned environment of the "core alkaline zone" (suitable for oxygen scavengers) and the "shell weak alkaline zone" (pH 8.0-8.5, suitable for corrosion inhibitors). This isolation effect ensures that the oxygen scavenger (sodium isoascorbate) in the core layer reacts efficiently under suitable alkaline conditions, and can fully remove dissolved oxygen in seawater within 4 hours (oxygen removal rate ≥96%). On the other hand, it avoids the influence of core alkalinity on the shell corrosion inhibitor, so that the hydrolysis rate of imidazoline is controlled within 5%, ensuring that it can stably form a protective film on the metal surface. Finally, the corrosion inhibition rate is stable at over 94.8% for 30 days, which solves the problem of "oxygen removal failure and corrosion inhibition rate fluctuation" caused by pH conflict in traditional solutions.

[0031] (2) Utilizing the thermosensitive properties of the copolymer hydrogel in the core layer (adapting to seawater temperature fluctuations), the swelling degree is adjusted according to the ambient temperature, and oxygen scavengers and catalytic components are released as needed to continuously remove dissolved oxygen to reduce oxidative corrosion. The copolymer in the shell layer has pH responsiveness (adapting to the weakly alkaline environment of seawater). When pH≥8.5, it swells and releases corrosion-inhibiting and bactericidal complex. Among them, imidazoline forms a protective film to block chloride ions, hexadecyltrimethylammonium bromide destroys the cell membrane of microorganisms and inhibits the formation of bioscale. Sodium tungstate forms a precipitation film with metal ions to inhibit pitting corrosion on the one hand, and complexes calcium and magnesium ions to interfere with the growth of inorganic salt lattice on the other hand, effectively inhibiting calcium carbonate / calcium sulfate scaling. This forms a dual mechanism to strengthen protection. Multiple functions are achieved through structural design to realize "release as needed and synergistic effect", which ultimately reduces the pipeline corrosion rate and scaling risk and extends the service life of seawater pipelines. Attached Figure Description

[0032] Figure 1Scanning electron microscope image of solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting microspheres with a three-layer core-shell structure. Detailed Implementation

[0033] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention; the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0034] Figure 1 This is a scanning electron microscope (SEM) image of a three-layered core-shell structured solid oxygen-scavenging, bactericidal, corrosion-inhibiting, and scale-inhibiting microsphere. The image clearly shows the core, intermediate, and shell layers. The overall particle size of the microspheres is approximately 3–4 μm, with a scale bar of 1 μm. Image acquisition was performed using field emission scanning electron microscopy (FE-SEM) at an accelerating voltage of 5 kV. The samples underwent metal sputtering treatment (such as Pt or Au) to enhance conductivity and imaging contrast. This image reflects the distinct layered structure, uniform particle size distribution, and clearly defined micro- and nanoporous structures of the corrosion inhibitor microspheres, contributing to a better understanding of their slow-release, bactericidal, and oxygen-scavenging mechanisms.

[0035] I. Core Layer Preparation

[0036] Based on 100g of core layer product, the formulation details of each raw material are as follows:

[0037] 28.5g of 2-acrylamido-2-methylpropanesulfonic acid needs to be added, with a molar ratio of 3:1 to 11.5g of N-vinylcaprolactam; N,N'-methylenebisacrylamide as a crosslinking agent and ammonium persulfate as an initiator are each added in an amount of 0.4g, and the two together account for 1.0% of the total mass of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam monomers (28.5g + 11.5g = 40g); 40g of sodium isoascorbate is added for deoxygenation, which accounts for 40% of the total mass of the core layer product; 4g of copper-L-histidine complex, which plays a catalytic role, is added, accounting for 10% of the mass of sodium isoascorbate.

[0038] Step A1: Dissolve 2-acrylamido-2-methylpropanesulfonic acid (28.5g) and N-vinylcaprolactam (11.5g) in 200mL of deionized water and stir until completely dissolved; add N,N'-methylenebisacrylamide (0.4g) and ammonium persulfate (0.4g), purge with ammonia gas to remove oxygen for 15min, and then stir and react at 60℃ for 24h to form transparent hydrogel microspheres (particle size 1-2mm).

[0039] Reaction mechanism: Ammonium persulfate (APS) decomposes upon heating to produce sulfate radicals (·SO4). - This process initiates free radical polymerization of the carbon-carbon double bond (C=C) of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam, forming a linear copolymer chain.

[0040] The diene bonds of N,N'-methylenebisacrylamide participate in polymerization simultaneously, and the linear chains are linked into a three-dimensional network structure (hydrogel) through cross-linking reaction.

[0041] Among them, the sulfonic acid group (-SO3H) of 2-acrylamido-2-methylpropanesulfonic acid is a strong acid group, which readily ionizes into -SO3 in water. - This endows the hydrogel with pH responsiveness (it can adjust swelling when exposed to seawater pH fluctuations).

[0042] The cyclic amide structure of N-vinylcaprolactam gives it temperature sensitivity (low critical solution temperature LCST≈35℃) – it remains swollen at actual seawater temperatures (5-30℃), providing a release channel for subsequent oxygen scavengers.

[0043] Step A2: Soak the hydrogel microspheres in an aqueous solution (200 mL) containing sodium isoascorbate (40 g) and copper-histidine complex (4 g), let them stand at 25°C for 6 h, and then dry them in a vacuum drying oven (45°C) for 3 h to obtain the core layer (hydrogel microspheres loaded with deoxygenation function).

[0044] Reaction mechanism: In the copper-histidine complex, C U 2+ The imidazole group of histidine (containing an imidazole ring) is linked via a coordination bond (C U 2+ +Histidine (containing imidazole ring) → C U- Histidine complex), which acts as a catalyst, accelerates the redox reaction of sodium isoascorbate with oxygen (without requiring a strongly alkaline environment). The reaction formula is as follows:

[0045]

[0046] The three-dimensional network of the hydrogel adsorbs sodium isoascorbate through diffusion, and forms a stable loading structure after drying (which can slowly release oxygen scavengers when it comes into contact with seawater).

[0047] II. Intermediate Layer Decoration

[0048] Based on 100g of intermediate layer product, the formulation details of each raw material are as follows:

[0049] 50g of silica nanoparticles with a particle size of 50nm are required as the basic raw material; 4g of 3-aminopropyltriethoxysilane is used, which accounts for 8% of the mass of the silica nanoparticles; 10g of 3-aminophenylboronic acid is added, with a molar ratio of 1:1 to 6.8g of catechol.

[0050] Step B1: Disperse 50g of silica nanoparticles in 300mL of ethanol and sonicate for 30min; add 4g of 3-aminopropyltriethoxysilane, reflux at 75℃ for 5h, centrifuge (5000r / min), wash 3 times with ethanol, and dry to obtain aminated SiO2.

[0051] Reaction Mechanism: The alkoxy group (-OC2H5) of the silane coupling agent undergoes a condensation reaction with the hydroxyl group (-OH) on the SiO2 surface to form a Si-O-Si covalent bond, grafting an amino group (-NH2) onto the SiO2 surface. The reaction formula is as follows:

[0052] SiO2-OH+NH2-(CH2)3-Si(OC2H5)3→Si(OC2H5)2-(CH2)3-NH2+C2H5OH

[0053] Aminated SiO2 can achieve loading of boric acid groups through the reaction of amino groups with the carboxyl groups of 3-aminophenylboronic acid.

[0054] Step B2: Disperse 50g of aminated SiO2 in 200mL of aqueous ethanol (volume ratio 1:1), add 10g of 3-aminophenylboronic acid and 2g of sodium carbonate as catalysts, and stir at 25℃ for 4h under acidic conditions of pH≈4.5; then add 6.8g of catechol, react at 30℃ for 2.5h, centrifuge (5000r / min), wash three times with ethanol, and dry to obtain the intermediate layer material.

[0055] Reaction Mechanism: The borate group (B(OH)2) of 3-aminophenylboronic acid undergoes a reversible condensation with the ortho-hydroxyl group (-OH) of catechol under acidic conditions (pH≈4.5) and in an aqueous ethanol solvent, forming a dynamic borate ester bond (-BO-). The reaction formula is as follows:

[0056]

[0057] This dynamic bond is stable at pH 8.0-8.5. When pH > 8.5, it dissociates and releases H⁺, maintaining the pH difference between the two sides of the middle layer (core layer pH ≈ 9, shell layer pH ≈ 8.0), thus achieving partitioned buffering.

[0058] III. Shell Coverage

[0059] Based on 100g of shell product, the formulation details of each raw material are as follows:

[0060] 15g of 3,4-dihydroxyphenylalanine (DOPA) needs to be added, with a molar ratio of 4:1 to 35g of 1H,1H,2H,2H-perfluorodecyl acrylate (FDA); 0.5g of ammonium persulfate is used, accounting for 1.0% of the total mass of DOPA and FDA monomers (15g + 35g = 50g), to initiate the polymerization reaction; 20g of imidazoline corrosion inhibitor is added, with a mass ratio of 4:1 to 5g of hexadecyltrimethylammonium bromide (CTAB), to jointly construct the corrosion inhibition and bactericidal system; 3g of sodium tungstate is used, accounting for 12% of the mass of the corrosion inhibition and bactericidal complex composed of imidazoline corrosion inhibitor and CTAB (20g + 5g = 25g).

[0061] Step C1: Dissolve DOPA (15g) and FDA (35g) in 200mL of Tris-HCl buffer at pH 8.5, add ammonium persulfate (0.5g), purge with nitrogen for 10min, and react at 60℃ for 4h to obtain a copolymer solution.

[0062] Reaction Mechanism: Ammonium persulfate initiates free radical copolymerization of the carbon-carbon double bonds of DOPA and FDA, forming a DOPA-FDA copolymer. The phenolic hydroxyl group (-OH) of DOPA endows the copolymer with two key properties: first, strong adhesion to metal surfaces (similar to mussel adhesive proteins); second, pH responsiveness—at pH ≥ 8.5, the phenolic hydroxyl group ionizes to -O. - The stretching of molecular chains causes the copolymer to swell. The FDA's perfluoroalkyl chains enhance the hydrophobicity of the copolymer, improving its erosion resistance in high-salt seawater environments.

[0063] Step C2: Mix imidazoline (20g), CTAB (5g), and sodium tungstate (3g) and dissolve them in 50mL of ethanol. Mix the mixture with DOPA-FDA copolymer solution (200mL) and spray it onto the surface of the core-intermediate layer composite microspheres using a spraying process (pressure 0.3MPa). Cur the mixture under nitrogen protection at 70℃ for 12h to obtain the finished product.

[0064] Reaction mechanism: Imidazoline binds to the copolymer through hydrophobic interactions. When pH ≥ 8.5, the copolymer swells (porosity > 20%), releasing imidazoline and forming an adsorption film on the metal surface through its polar groups (-NH—), thus blocking chloride ion corrosion.

[0065] CTAB's quaternary ammonium group (-N) + (CH3)3) binds to the negative charge of the bacterial cell membrane, disrupting the membrane structure (bactericidal).

[0066] Sodium tungstate (WO4) 2- It provides protection through a dual mechanism:

[0067] (1) With metal ions (such as Fe) 2+ It forms a sparingly soluble precipitate film, inhibiting pitting corrosion;

[0068] (2) Its anion WO4 2- Complexing Ca in seawater 2+ Mg 2+ Plasma interferes with the growth of calcium carbonate / calcium sulfate crystals and inhibits inorganic salt scaling (according to HG / T3778-2005 standard).

[0069] Specifically, in a pH 8.0–8.5 zone environment maintained by dynamic borate ester bonds in the intermediate layer:

[0070] Sodium tungstate exhibits stable and efficient corrosion inhibition and scale inhibition functions, unaffected by the strong alkalinity of the core layer (pH≈9). Compared to traditional compound reagents (pH 8.5–9 compromise range), its scale inhibition efficiency is improved by more than 40% (because excessive alkalinity can lead to WO4). 2- With Ca 2+ (Decreased binding capacity); the FeWO4 in the precipitated membrane has lower solubility in a weakly alkaline environment, extending the lifespan of the protective membrane to 2.3 times that of traditional solutions.

[0071] All tests are conducted in accordance with international / industry standards.

[0072] Corrosion inhibition rate: According to GB / T18175-2014 "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotary Coating Method"

[0073] Deoxygenation rate: According to ASTM D888-18, "Test Method for Dissolved Oxygen in Water".

[0074] Sterilization rate: According to "NACETM0194-2014 Evaluation of the Efficacy of Sterilizers for Oilfield Water Injection"

[0075] pH buffer capacity: determined by potentiometric titration according to GB / T9724-2007 General Rules for the Determination of pH Value of Chemical Reagents. Example

[0076] The basic scheme involves a core layer with a molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam of 3.0:1, loaded with 40g of sodium isoascorbate, of which the copper-L-histidine complex accounts for 10% (4g) of the oxygen scavenger mass, and the reaction is carried out at 60℃ for 24 hours. The intermediate layer contains a middle layer with a molar ratio of 3-aminophenylboronic acid to catechol of 1:1, using 50nm silica nanoparticles dispersed in aqueous ethanol (volume) under acidic conditions of pH≈4.5. In a mixture of 1:1 ratio, sodium carbonate (2g) was added as a catalyst, and the reaction was carried out at 30°C for 2.5 hours. The molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate in the shell was 4.1:1, the mass ratio of imidazoline to hexadecyltrimethylammonium bromide was 4.1:1 (i.e., 20.5g:5g), and sodium tungstate accounted for 12% (i.e., 3.06g) of the corrosion-inhibiting and bactericidal complex. The mixture was cured at 70°C and 0.3MPa for 12 hours.

[0077] Performance tests show that the deoxygenation rate reaches 96.8% after 4 hours at 25℃, the corrosion inhibition rate is 95.2% after 30 days at 25℃, the sulfate-reducing bacteria kill rate reaches 99.9% after 7 days, the buffer capacity in the pH range of 8.0-8.5 is 0.155 mol / pH, the contact angle of the shell in seawater is 112° (tested using the hanging drop method), and the membrane lifetime exceeds 90 days at a flow rate of 2 m / s (tested using the weight loss method). Example

[0078] In the low-proportion boundary scheme, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam in the core layer is adjusted to 2.8:1, the molar ratio of 3-aminophenylboronic acid to catechol in the intermediate layer is 1:0.95, the molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate in the shell layer is 4.0:1, and the mass ratio of imidazoline to hexadecyltrimethylammonium bromide is 4.0:1.

[0079] Key performance tests showed that the oxygen removal rate at 30°C for 4 hours was 94.3%, a decrease of 2.5% compared to Example 1, mainly due to the reduced proportion of N-vinylcaprolactam; the buffer capacity in the pH 8.0-8.5 range was 0.142 mol / pH, a decrease of 8.4% compared to Example 1, due to insufficient catechol dosage; the shell contact angle was 105°, a decrease of 7° compared to Example 1, which is related to the reduced proportion of 1H,1H,2H,2H-perfluorodecyl acrylate. Example

[0080] In the high-proportion boundary scheme, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam in the core layer is adjusted to 3.2:1, the molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate in the shell layer is 4.2:1, and the mass ratio of imidazoline to hexadecyltrimethylammonium bromide is 4.2:1.

[0081] Key performance tests showed that the corrosion inhibition rate at 40°C was 93.7%, a decrease of 1.5% compared to Example 1, due to the enhanced hydrophilicity of 2-acrylamido-2-methylpropanesulfonic acid; the shell contact angle was 118°, an increase of 6° compared to Example 1, thanks to the increased proportion of 1H,1H,2H,2H-perfluorodecyl acrylate; and the shedding rate at a high flow rate of 3 m / s was 2.8%, indicating optimized erosion resistance. Example

[0082] For extreme working conditions of high salt and high temperature, with a corrosive medium of 45000 mg / L chloride ion concentration, 45℃ temperature and 3 m / s flow rate, the proportion of copper-L-histidine complex in the core layer is increased to 15%, and the molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate in the shell layer is 4.2:1.

[0083] Extreme performance tests showed that the corrosion inhibition rate reached 92.3% after 30 days, far exceeding the ≤70% of the traditional method; the oxygen removal half-life at 45℃ was 48h, significantly longer than the ≤12h of the nitrite method; the shell swelling rate at pH 8.5 was 58%, lower than the >85% of the polydopamine method; and the dynamic bond storage modulus G' at 45℃ was 1.1×10⁻⁶. 4 Pa, which is much higher than the ≤10³ Pa of the physical adsorption layer.

[0084] Comparative Example 1:

[0085] Traditional compounding methods involve directly mixing 40g sodium nitrite, 20g imidazoline, 5g cetyltrimethylammonium bromide, and 3g sodium tungstate, without a core-shell structure or temperature control process.

[0086] Performance tests showed that the corrosion inhibition rate was only 68.2% at pH 8.5, a decrease of 27.0% compared to Example 1; the hydrolysis rate of imidazoline reached 31.6% at pH 9.0, an increase of 26.6% compared to Example 1; and the kill rate of sulfate-reducing bacteria was 85%, a decrease of 14.9% compared to Example 1, highlighting the performance defects of the traditional scheme due to the lack of zoning design.

[0087] Comparative Example 2:

[0088] In the scheme lacking an intermediate layer, the core and shell layers are formulated the same as in Example 1, but the core and shell layers are in direct contact without an intermediate buffer layer.

[0089] Performance tests showed that the corrosion inhibition rate fluctuated by ±18.5% within the pH range of 7-9 due to the interpenetration of pH between the core and shell layers; the corrosion inhibition rate was only 69.5% at 40℃, as temperature accelerated the hydrolysis of the corrosion inhibitor; and the film life was only 18 days at a flow rate of 2m / s, due to insufficient structural stability caused by the lack of intermediate layer protection.

[0090] Comparative Example 3:

[0091] In the scheme where the shell layer has no pH response, the shell layer is replaced with a non-responsive material, polybutyl acrylate (CAS9003-49-0), and the core layer and intermediate layer are the same as in Example 1.

[0092] Performance tests showed that at pH 8.5, the corrosion inhibitor release rate was only 15% after 24 hours, a decrease of 77% compared to Example 1; the corrosion inhibition rate after 30 days was 72.4%, a decrease of 22.8% compared to Example 1; and the shell contact angle was 82°, a decrease of 30° compared to Example 1. The increased hydrophilicity caused the corrosion inhibition film to easily fall off.

[0093] Comparative Example 4:

[0094] The shell layer is made of polydopamine electrostatic adsorption (without 1H,1H,2H,2H-perfluorodecyl acrylate), the middle layer is physically mixed borax (without dynamic borate ester bonds), and the core layer is the same as in Example 1.

[0095] Performance tests showed that the shell's resistance to seawater erosion decreased significantly, the pH buffer capacity of the middle layer was less than 50% of that in Example 1, and the 30-day corrosion inhibition rate was more than 25% lower than that in Example 1, confirming the necessity of the dynamic bonding and core-shell co-design of this invention.

[0096] The solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agents prepared in Examples 1, 2, 3, and 4 and Comparative Examples 1, 2, 3, and 4 were used as test samples and were numbered HSJ1001, HSJ1002, HSJ1003, HSJ1004, HSJ1005, HSJ1006, HSJ1007, and HSJ1008 in sequence.

[0097] Product effectiveness test

[0098] 1. Corrosion inhibition rate test at different temperatures

[0099] Corrosive media conditions:

[0100] The total mineralization was set at 35,000 mg / L, with the ionic composition precisely matched to the marine environment, including Na. + 10770mg / L, Cl - 19350mg / L, Mg 2+ 1290mg / L, Ca 2+ 410 mg / L, SO4 2- 2710 mg / L, HCO3- 140 mg / L; simultaneously simulating the dissolved oxygen state of seawater surface, the dissolved oxygen concentration was controlled at 8 mg / L, and sulfate-reducing bacteria (SRB, concentration 10) were added. 5 CFU / mL), iron bacteria (concentration 10) 4 A compound system of CFU / mL was used to recreate the biological corrosion scenario faced by seawater pipelines;

[0101] Experimental parameters: Q235 carbon steel test pieces (size 20mm×20mm×3mm, pre-treated with degreasing and derusting) commonly used in seawater pipelines were selected. The corrosion cycle was set at 7 days to simulate long-term pipeline operation. The rotation speed was controlled at 100r / min to reproduce the shear force of seawater flow. Temperature gradients of 10℃, 20℃, 30℃, and 40℃ were set to cover seasonal temperature changes in seawater and local temperature rise conditions in the pipeline, so as to comprehensively test the protective efficacy of corrosion inhibitors under temperature variables.

[0102] Test method: The solid oxygen-removing, bactericidal, corrosion-inhibiting, and scale-inhibiting agents prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were added to the corrosive medium at a concentration of 0.5 g / L. The corrosion rate of the steel sheet was tested by the weight loss method, and the corrosion inhibition rate was calculated (corrosion inhibition rate = [(v0-v) / v0]×100%), where v0 is the corrosion rate of the blank group and v is the corrosion rate of the group with added corrosion inhibitor. The results are shown in Table 1.

[0103] Table 1: Corrosion inhibition rate (%) at different temperatures

[0104]

[0105] Examples 1 to 3 consistently maintained a corrosion inhibition rate of over 92% within the 10-40℃ range, with fluctuations of ≤4.2%. This is primarily due to the thermo-sensitive synergistic effect of the core layer's 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam copolymer hydrogel. The low critical temperature (LCST) of N-vinylcaprolactam adapts to seawater temperature fluctuations. At low temperatures (10-20℃), the hydrogel exhibits high swelling, ensuring efficient release of sodium isoascorbate for oxygen removal. At high temperatures (30-40℃), it moderately shrinks, reducing ineffective loss of the oxygen remover. Simultaneously, the buffering effect of the dynamic borate ester bonds in the intermediate layer (buffer capacity of 0.14-0.16 mol / pH in the pH 8.0-8.5 range) stabilizes the shell microenvironment, inhibiting imidazoline hydrolysis and ensuring that the corrosion inhibition function is unaffected by drastic temperature changes.

[0106] In Example 4, under extreme conditions of high salt (Cl⁻=45000mg / L) and high temperature (40℃), the corrosion inhibition rate still reached 92.3%. This was due to the increased proportion of copper-L-histidine complex in the core layer (15%), which enhanced the catalytic oxygen removal efficiency, and the improved hydrophobicity of the 1H,1H,2H,2H-perfluorodecyl acrylate component in the shell layer, which resisted the penetration and erosion of high salt solution and maintained the structural integrity.

[0107] Comparative Example 1 (traditional compound) lacks a core-shell and temperature-sensitive design. Increased temperature (40℃ compared to 10℃) accelerates nitrite decomposition, increases imidazoline hydrolysis rate to 31.6%, and causes a sharp drop in corrosion inhibition rate of 12.5%. Comparative Example 2 (lacking an intermediate layer) exhibits direct pH interpenetration between the core and shell, exacerbating corrosion inhibitor hydrolysis at high temperatures, resulting in a corrosion inhibition rate of only 69.5% at 40℃. Comparative Example 3 (without a pH-responsive shell) cannot release corrosion inhibitors as needed, leading to delayed protective film formation at high temperatures and a continuous decrease in corrosion inhibition rate with increasing temperature. Comparative Example 4 (patent reproduction) lacks dynamic buffering and temperature-sensitive synergy, resulting in poor structural stability. Its corrosion inhibition rate at 40℃ is 32.6% lower than Example 1, verifying the crucial role of the core-shell-dynamic bond-temperature-sensitive synergistic design of this invention in achieving stability over a wide temperature range.

[0108] 2. Corrosion resistance test at different seawater pH levels

[0109] Corrosive media conditions: Same as the basic formula for "different temperature tests", adjust the pH to 7.0 (acidic polluted seawater), 8.0 (natural seawater pH), 9.0 (alkaline conditions), and 10.0 (extreme alkalinity), and keep the other parameters (dissolved oxygen, microorganisms, mineralization) unchanged.

[0110] Experimental parameters: 25℃ was selected as the test temperature to match the typical characteristics of the annual average temperature of seawater; a 7-day corrosion cycle was set to simulate the continuous erosion process of corrosive media during long-term pipeline operation; the rotation speed was controlled at 100r / min using a rotating plate apparatus to reproduce the shear force effect of seawater flow on the inner wall of the pipeline; the amount of corrosion inhibitor added was kept at 0.5g / L (consistent with the previous test system) to ensure the principle of single variable, thereby accurately verifying the anti-corrosion efficacy and long-term effectiveness of the corrosion inhibitor under stable environmental conditions.

[0111] Test method: The pH of the corrosive medium was adjusted by hydrochloric acid / sodium hydroxide, and the corrosion inhibition rate and imidazoline hydrolysis rate of the steel sheet were tested (the residual amount of imidazoline released from the shell was detected by high performance liquid chromatography). The results are shown in Table 2.

[0112] Table 2: Corrosion inhibition rate (%) and imidazoline hydrolysis rate (%) at different seawater pH levels

[0113]

[0114] In Example 1, the corrosion inhibition rate remained stable at 93.2%-96.5% in a medium environment with a pH of 7.0-10.0, and the imidazoline hydrolysis rate was consistently <5%. This is primarily due to the synergistic regulation of the dynamic borate ester bonds in the intermediate layer and the pH-responsive structure of the shell layer. The dynamic bonds formed by the 3-aminophenylboronic acid and catechol in the intermediate layer have a buffer capacity of 0.14-0.16 mol / pH in the pH range of 8.0-8.5. This buffer can precisely isolate the pH environment of the core and shell layers through reversible dissociation / binding of H+. Even if the overall pH of the medium fluctuates to 8.5-10.0, the pH of the shell microenvironment remains stable at 8.0-8.5 (the stable range of the imidazoline corrosion inhibitor), avoiding… The core layer is free from alkaline conditions (pH≈9) that directly corrode the shell layer imidazoline. Simultaneously, the 3,4-dihydroxyphenylalanine and 1H,1H,2H,2H-perfluorodecyl acrylate copolymer in the shell layer is sensitive to the overall pH of the medium. When the medium pH ≥ 8.5 (such as natural seawater or alkaline conditions), the copolymer swells due to the ionization of phenolic hydroxyl groups (swelling rate 55-70%, porosity > 20%), directionally releasing imidazoline to the pipe surface to form a protective film. At this time, the microenvironment pH of the shell layer is still maintained at 8.0-8.5, ensuring the stability of the released imidazoline molecular structure. This solves the contradiction between "the need to release corrosion inhibitors under high pH conditions" and "imidazoline is easily hydrolyzed under high pH conditions".

[0115] Example 4 still maintains a release rate of 64.5% and a low hydrolysis rate of 5.8% under extreme alkalinity (pH 10.0). This is because the increased proportion of copper-L-histidine complex in the core layer (15%) enhances the deoxygenation efficiency, and the perfluorinated components in the shell layer improve the alkali resistance, thus offsetting the erosion of the structure by high pH.

[0116] Comparative Example 1 (traditional compound) lacked a zoned design, and the hydrolysis rate of imidazoline increased from 22.3% (pH 7.0) to 38.5% (pH 10.0) with increasing pH, while the corrosion inhibition rate decreased by 23.8% with pH fluctuations. Comparative Example 4 (patent reproduction) had a physical mixed borax middle layer (without dynamic buffering) and lacked pH-responsive copolymers in the shell layer. At pH 8.5, the release rate was only 59.8% and the hydrolysis rate reached 28.7%, verifying the key value of the dynamic bonding and pH-responsive synergistic design of this invention for stability over a wide pH range.

[0117] By analyzing the data from these four test samples, we can cover both normal operating conditions (pH 7.0-10.0) and extremely alkaline environments (pH 10.0), thus verifying the universality of the technology. Other examples / comparative examples (such as Examples 2 and 3 or Comparative Examples 2 and 3) are experiments with local parameter adjustments, and their performance differences are already implied in the core comparison, so there is no need to elaborate on them separately.

[0118] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A solid oxygen scavenging bactericidal corrosion and scale inhibitor for seawater oil well pipes, characterized in that, It comprises a three-layer core-shell structure: The core layer is composed of a copolymer hydrogel of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam being 2.8-3.2:1, and loaded with sodium erythorbate and copper-L-histidine complex, wherein the copper-L-histidine complex accounts for 5-15% of the mass of sodium erythorbate; The intermediate layer is formed by connecting 3-aminobenzene boronic acid functionalized silica nanoparticles and catechol through dynamic boronate ester bonds, wherein the molar ratio of 3-aminobenzene boronic acid to catechol is 1:0.95-1.05, and the particle size of the silica nanoparticles is 45-55 nm, and the buffer capacity of the dynamic boronate ester bonds in the intermediate layer is 0.14-0.16 mol / pH in the pH 8.0-8.5 interval; The shell layer is composed of a copolymer of 3,4-dihydroxyphenylalanine and 1H,1H,2H,2H-perfluorodecyl acrylate, wherein the molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate is 4.0-4.2:1, and the corrosion and bactericidal composite is coated, wherein the corrosion and bactericidal composite comprises imidazoline corrosion inhibitor, cetyltrimethylammonium bromide and sodium tungstate, and the mass ratio of imidazoline to cetyltrimethylammonium bromide is 4.0-4.2:1, and sodium tungstate accounts for 12% of the mass of the corrosion and bactericidal composite.

2. The solid oxygen scavenging, bactericidal, corrosion and scale inhibitor for seawater oil well pipes according to claim 1, characterized in that: The crosslinking agent of the core layer copolymer hydrogel is N,N'-methylene bisacrylamide, and the amount used is 0.8-1.5% of the total mass of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam.

3. The solid oxygen scavenging, bactericidal, corrosion inhibiting and scale inhibiting agent for seawater oil well pipes according to claim 1, characterized in that: The swelling rate of the shell layer 3,4-dihydroxyphenylalanine-1H,1H,2H,2H-perfluorodecyl acrylate copolymer is 55-70% at pH≥8.5, and the porosity is >20%.

4. The method for manufacturing the solid oxygen scavenging, bactericidal, corrosion and scale inhibiting agent for seawater oil well pipes according to any one of claims 1 to 3, characterized in that, It comprises the following steps: A. Core layer preparation: A1: Dissolve 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam in deionized water according to the molar ratio 2.8-3.2:1, add N,N'-methylene bisacrylamide crosslinking agent and ammonium persulfate initiator, and react at 60°C under nitrogen protection for 24 hours to form hydrogel microspheres; A2: Immerse the microspheres in a solution containing sodium erythorbate and copper-L-histidine complex, and vacuum dry to obtain a core layer loaded with an oxygen scavenger; B. Intermediate layer modification: B1: Disperse silica nanoparticles in ethanol, add 3-aminopropyltriethoxysilane, and reflux at 70-80°C for 4-6 hours to obtain aminated SiO2; B2: React aminated SiO2 with 3-aminobenzene boronic acid in water-ethanol solvent at pH=4.5, then add catechol, and react at 30°C for 2-3 hours to form a dynamic buffer layer; C. Shell coating: C1: 3,4-dihydroxyphenylalanine and 1H,1H,2H,2H-perfluorodecyl acrylate are dissolved in Tris-HCl buffer solution with pH 8.5 at a molar ratio of 4.0-4.2:1, ammonium persulfate is added, and the copolymer solution is obtained by polymerization at 60°C under nitrogen protection for 3-5 hours; C2: imidazoline, cetyltrimethylammonium bromide, and sodium tungstate are mixed in proportion, sprayed together with the copolymer solution to the surface of the intermediate layer, and cured at 70°C for 12 hours to form a shell layer.

5. The manufacturing method according to claim 4, characterized in that: The amount of ammonium persulfate used in step A1 is 0.8-1.2% of the total mass of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam.

6. The manufacturing method of claim 4, wherein: In step B2, the molar ratio of 3-aminobenzoic acid to catechol is 1:1, and the reaction temperature is 30°C.

7. The manufacturing method of claim 4, wherein: In C2, the spraying pressure is 0.25-0.35 MPa, and the curing temperature is 70°C.

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