Manufacturing method of solid deoxidizing and sterilizing corrosion and scale inhibitor for seawater oil well pipeline

Abstract

The invention relates to the technical field of anti-corrosion reagents, and particularly discloses a manufacturing method of a solid deoxidizing and sterilizing corrosion and scale inhibitor for seawater oil well pipelines, the solid deoxidizing and sterilizing corrosion and scale inhibitor comprises a three-layer core-shell structure, the core layer is composed of copolymerized hydrogel of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam, and the core layer is composed of copolymerized hydrogel of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam; sodium erythorbate and a copper-L-histidine complex are loaded; the middle layer is formed by connecting 3-aminophenylboronic acid functionalized silicon dioxide nano-particles and catechol through dynamic boric acid ester bonds; the shell layer is formed by coating a corrosion inhibition and sterilization compound with a copolymer of 3, 4-dihydroxyphenylalanine and 1H, 1H, 2H, 2H-perfluorodecyl acrylate; through the synergistic effect of a core-shell structure and a dynamic bond, the pH conflict between a deoxidant and a corrosion inhibitor in a traditional reagent is broken through, the integrated functions of deoxygenation, sterilization, corrosion inhibition and scale inhibition are achieved, microbial corrosion can be effectively inhibited, the scaling risk is reduced, the service life of a seawater pipeline is prolonged, and the marine complex working condition is adapted.

Description

Technical Field

[0001] The invention belongs to the technical field of anti-corrosion agents, and in particular relates to a method for manufacturing a solid deoxygenating, sterilizing, corrosion-inhibiting and scale-inhibiting agent for seawater oil well pipelines. Background Art

[0002] During the long-term operation of seawater pipelines, the inner walls of these pipelines are susceptible to a combination of erosion factors, triggering 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 walls to gradually rust and thin. Simultaneously, microorganisms in seawater (such as sulfate-reducing bacteria and iron bacteria) form a slimy biofilm on the pipeline surface. The acidic substances and hydrogen sulfide produced by their metabolism further exacerbate metal corrosion, forming localized pits and even small holes. Furthermore, the high concentration of chloride ions in seawater penetrates the protective film on the metal surface, accelerating the oxidative dissolution of the pipeline. Furthermore, the calcium and magnesium ions in seawater form deposits, causing under-scale corrosion and pipeline blockage. These combined problems can reduce the pipeline's pressure resistance, reduce water transmission efficiency, and, in severe cases, cause leakage. This not only increases repair and replacement costs but also poses safety risks such as seawater pollution.

[0003] To alleviate the corrosion problem of seawater pipelines, the industry usually uses multifunctional chemical reagents for protection. These reagents need to simultaneously deal with the damage caused by oxidation, microorganisms, and chloride ions. Traditional reagents of this type generally contain three core components: first, deoxidizers, such as nitrites, which can react with dissolved oxygen in seawater to reduce oxygen oxidation of metals; second, corrosion inhibitors, such as imidazoline compounds, which can form a protective film on the metal surface to block the erosion of corrosive substances such as chloride ions; third, bactericides, such as quaternary ammonium salts, are used to kill microorganisms in seawater and prevent the formation of biofilms; and fourth, scale inhibitors, such as organic phosphonates, which inhibit the growth of calcium carbonate lattices. These ingredients are mixed into solid or liquid reagents and added to the pipelines on a regular basis to play a comprehensive protective role.

[0004] However, there are significant contradictions in the composition design of the composite reagents in the prior art: on the one hand, nitrite-based oxygen scavengers need to be stable and efficiently deoxygenate in an alkaline environment with a pH greater than 9; on the other hand, imidazolines are slow.

[0005] At pH levels above 8.5, the corrosion inhibitor undergoes molecular hydrolysis, significantly reducing its ability to form a protective film on metal surfaces. Existing solid composite reagents cannot physically isolate the two components, resulting in a compromised pH (typically between 8.5 and 9). Within this pH range, nitrite's oxygen removal efficiency is significantly reduced (due to insufficient alkalinity), while imidazoline's stability cannot be guaranteed (due to high alkalinity). This ultimately leads to large fluctuations in corrosion inhibition and unstable protection. Furthermore, scale inhibitors (such as organic phosphonates) precipitate with calcium ions under alkaline conditions, exacerbating scaling. These contradictions directly limit the reliable application of composite reagents for long-term corrosion protection of seawater pipelines. Summary of the Invention

[0006] The object of the present invention is to provide a method for producing a solid deoxygenating, sterilizing, corrosion inhibiting and scale inhibitor for seawater oil well pipelines, so as to solve the problems raised in the above background technology.

[0007] A first aspect of the present invention provides a solid deoxygenating, sterilizing, corrosion inhibiting and scale inhibitor for seawater oil well pipelines.

[0008] Specifically, a solid deoxidizing, sterilizing, corrosion-inhibiting and scale-inhibiting agent for seawater oil well pipelines 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, wherein the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam in the copolymer hydrogel is 2.8-3.2:1, and is loaded with sodium erythorbate and a copper-L-histidine complex, wherein the copper-L-histidine complex accounts for 5-15% of the mass of the sodium erythorbate; The middle layer is composed of 3-aminophenylboronic acid functionalized silica nanoparticles and catechol connected by dynamic boronate bonds, wherein the molar ratio of 3-aminophenylboronic acid to catechol is 1:0.95-1.05, and the silica nanoparticles have a particle size of 45-55 nm; Shell: It is composed of a corrosion-inhibiting and bactericidal composite 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, and the corrosion-inhibiting and bactericidal composite includes an 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 composite.

[0009] 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.

[0010] Preferably, the buffer capacity of the dynamic borate ester bond in the intermediate layer is 0.14-0.16 mol / pH in the pH range of 8.0-8.5.

[0011] Preferably, the shell layer 3,4-dihydroxyphenylalanine-1H,1H,2H,2H-perfluorodecyl acrylate copolymer has a swelling ratio of 55-70% at a pH of ≥8.5, and a porosity of >20%.

[0012] A second aspect of the present invention provides a method for producing a solid deoxygenating, sterilizing, corrosion inhibiting and scale inhibitor for seawater oil well pipelines.

[0013] Specifically, a method for manufacturing a solid deoxygenating, sterilizing, corrosion inhibiting and scale inhibitor for seawater oil well pipelines comprises the following steps: A. Nuclear lamina preparation: A1: Dissolve 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam in deionized water at a molar ratio of 2.8-3.2:1, add N,N'-methylenebisacrylamide crosslinker and ammonium persulfate initiator, and react at 60°C under nitrogen for 24 hours to form hydrogel microspheres; A2: Immersing the microspheres in a solution containing sodium isoascorbate and copper-L-histidine complex and vacuum drying to obtain a core layer loaded with oxygen scavengers; B. Middle layer modification: B1: Disperse silica nanoparticles in ethanol, add 3-aminopropyltriethoxysilane, and reflux at 70-80°C for 4-6 hours to obtain amino SiO2; B2: Amination of SiO2 and 3-aminophenylboronic acid was reacted in an acidic solution (pH ≈ 4.5) in an aqueous ethanol solvent, followed by the addition of catechol. The reaction was continued 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 were dissolved in a Tris-HCl buffer solution at a molar ratio of 4.0-4.2:1 at pH 8.5, and ammonium persulfate was added. The mixture was polymerized at 60°C under nitrogen protection for 3-5 hours to obtain a copolymer solution. C2: imidazoline, hexadecyltrimethylammonium bromide, and sodium tungstate were mixed in proportion, sprayed together with the copolymer solution onto the surface of the intermediate layer, and cured at 70° C. for 12 hours to form a shell layer.

[0014] Preferably, 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.

[0015] Preferably, in step B2, the molar ratio of 3-aminophenylboronic acid to catechol is 1:1, and the reaction temperature is 30°C.

[0016] Preferably, the spray pressure in C2 is 0.25-0.35 MPa, and the curing temperature is 70°C.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The dynamic borate bond in the middle layer has a precise pH buffering capacity (buffering capacity of 0.15 mol / pH), and can stably maintain the partitioned environment of the "core alkaline zone" (suitable for deoxidizers) and the "shell weak alkaline zone" (pH8.0-8.5, suitable for corrosion inhibitors) by reversibly dissociating and combining hydrogen ions. This isolation effect ensures that the deoxidizer (sodium isoascorbate) in the core layer reacts efficiently under suitable alkaline conditions, and can fully remove dissolved oxygen in seawater within 4 hours (deoxidation rate ≥96%). On the other hand, it avoids the influence of the alkalinity of the core layer on the corrosion inhibitor in the shell layer, so that the hydrolysis rate of imidazoline is controlled within 5%, ensuring that it stably forms a protective film on the metal surface, and finally achieving a 30-day corrosion inhibition rate of more than 94.8%, solving the problem of "deoxidation failure and corrosion inhibition rate fluctuation" caused by pH conflict in traditional solutions.

[0018] (2) The thermosensitive properties of the copolymer hydrogel in the core layer (adapting to the temperature fluctuation of seawater) are utilized to adjust the swelling degree according to the ambient temperature, release the oxygen scavenger and catalytic components on demand, and continuously remove dissolved oxygen to reduce oxidative corrosion. The copolymer in the shell layer is pH responsive (adapting to the weak alkaline environment of seawater), and swells and releases corrosion-inhibiting and bactericidal complexes when the pH is ≥8.5. Among them, imidazoline forms a protective film to block chloride ions, and hexadecyltrimethylammonium bromide destroys the cell membrane of microorganisms and inhibits the formation of biofouling. Sodium tungstate forms a precipitation film with metal ions to inhibit pitting corrosion, and on the other hand, it complexes calcium and magnesium ions to interfere with the growth of inorganic salt lattice, effectively inhibiting the scaling of calcium carbonate / calcium sulfate, forming a dual mechanism to enhance protection. Multiple functions are achieved through "on-demand release and synergistic effect" through structural design, ultimately reducing the corrosion rate and scaling risk of the pipeline and extending the service life of the seawater pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope image of the three-layer core-shell structure solid deoxygenation, sterilization, corrosion inhibition and scale inhibitor microspheres. DETAILED DESCRIPTION

[0020] In order to make those skilled in the art more clearly understand the technical solutions of the present invention, the following examples are listed for illustration. It should be pointed out that the following examples do not limit the scope of protection claimed by the present invention, and the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Figure 1 This is a scanning electron microscope (SEM) image of a three-layer core-shell structured solid deoxidizing, bactericidal, corrosion-inhibiting, and scale-inhibiting microsphere. The image clearly demonstrates the core, intermediate, and shell structures. The overall particle size of the microspheres is approximately 3–4 μm. The scale bar is 1 μm. The image was acquired using a field emission scanning electron microscope (FE-SEM) at an accelerating voltage of 5 kV. The sample was metallized (e.g., with Pt or Au) to enhance conductivity and image contrast. The image demonstrates the distinct structural layers, uniform particle size distribution, and clear surface micro- and nanopore structure of the corrosion inhibitor microspheres, helping to understand the mechanisms of their slow-release, bactericidal, and deoxidizing functions.

[0022] 1. Nuclear Layer Preparation Taking 100g of core layer product as the measurement basis, the formula details of each raw material are as follows: 28.5g of 2-acrylamido-2-methylpropanesulfonic acid needs to be added, and the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to 11.5g of N-vinylcaprolactam is 3:1; the amount of N,N'-methylenebisacrylamide as a cross-linking agent and ammonium persulfate as an initiator is 0.4g each, 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 needs to be added for deoxygenation, which accounts for 40% of the total mass of the core layer product; the amount of copper-L-histidine complex used as a catalyst is 4g, which accounts for 10% of the mass of sodium isoascorbate.

[0023] Step A1: Dissolve 2-acrylamido-2-methylpropanesulfonic acid (28.5 g) and N-vinylcaprolactam (11.5 g) in 200 mL of deionized water and stir until completely dissolved. Add N,N'-methylenebisacrylamide (0.4 g) and ammonium persulfate (0.4 g). After deoxygenation by passing ammonia gas for 15 minutes, stir and react at 60°C for 24 hours to form transparent hydrogel microspheres (particle size 1-2 mm).

[0024] Reaction mechanism: Ammonium persulfate (APS) decomposes under heat to produce sulfate radicals (·SO4 -), initiating free radical polymerization of the carbon-carbon double bonds (C=C) of 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam to form a linear copolymer chain; The diene bonds of N,N'-methylenebisacrylamide participate in polymerization simultaneously, connecting the linear chains into a three-dimensional network structure (hydrogel) through cross-linking reaction.

[0025] Among them: the sulfonic acid group (-SO3H) of 2-acrylamido-2-methylpropanesulfonic acid is a strong acidic group and is easily ionized to -SO3 in water. - , giving the hydrogel pH responsiveness (adjustable swelling when encountering pH fluctuations in seawater); The cyclic amide structure of N-vinylcaprolactam makes it temperature-sensitive (lower critical solution temperature LCST≈35°C) - it remains swollen at the actual seawater temperature (5-30°C), providing a release channel for subsequent oxygen scavengers.

[0026] Step A2: The hydrogel microspheres were immersed in an aqueous solution (200 mL) containing sodium isoascorbate (40 g) and copper-histidine complex (4 g), and allowed to stand at 25°C for 6 h. Subsequently, the hydrogel microspheres were dried in a vacuum drying oven (45°C) for 3 h to obtain a core layer (hydrogel microspheres loaded with deoxygenation function).

[0027] Reaction mechanism: In the copper-histidine complex, C U 2+ The imidazole group of histidine (containing an imidazole ring) is bound by a coordination bond (C U 2+ + histidine (containing imidazole ring) → C U- Histidine complex), which acts as a catalyst to accelerate the redox reaction of sodium isoascorbate with oxygen (no strong alkaline environment is required), the reaction formula is:

[0028] The three-dimensional network of the hydrogel adsorbs sodium isoascorbate through diffusion, forming a stable loading structure after drying (the scavenger can be slowly released when it encounters seawater).

[0029] 2. Middle layer modification Taking 100g of the intermediate layer product as the measurement basis, the formula details of each raw material are as follows: 50g of silica nanoparticles with a particle size of 50nm are required as the basic raw material; the amount of 3-aminopropyltriethoxysilane used is 4g, which accounts for 8% of the mass of the silica nanoparticles; 10g of 3-aminophenylboric acid is required, and the molar ratio of 3-aminophenylboric acid to 6.8g of catechol is 1:1.

[0030] Step B1: Disperse 50 g of silica nanoparticles in 300 mL of ethanol and ultrasonicate for 30 min; add 3-aminopropyltriethoxysilane (4 g), reflux at 75 °C for 5 h, centrifuge (5000 rpm), wash with ethanol three times, and dry to obtain amino SiO2.

[0031] 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, and the amino group (-NH2) is grafted onto the SiO2 surface. The reaction formula is: SiO2-OH+NH2-(CH2)3-Si(OC2H5)3→Si(OC2H5)2-(CH2)3-NH2+C2H5OH The amination-treated SiO2 can react with the carboxyl group of 3-aminophenylboronic acid through the amino group to achieve the loading of boronic acid groups.

[0032] Step B2: Disperse the aminated SiO2 (50 g) in 200 mL of aqueous ethanol (volume ratio 1:1), add 3-aminophenylboronic acid (10 g) and sodium carbonate (2 g) as catalysts, stir and react at 25°C under acidic conditions of pH ≈ 4.5 for 4 hours; then add catechol (6.8 g), react at 30°C for 2.5 hours, centrifuge (5000 r / min), wash 3 times with ethanol, and then dry to obtain the intermediate layer material.

[0033] Reaction Mechanism: The boronic acid group (B(OH)2) of 3-aminophenylboronic acid and the ortho-hydroxyl group (-OH) of catechol undergo reversible condensation under acidic conditions (pH ≈ 4.5) and in aqueous ethanol solvent to form a dynamic borate ester bond (-BO-). The reaction formula is:

[0034]

[0035] This dynamic bond exists stably at pH 8.0-8.5, and dissociates to release H⁺ when pH>8.5, maintaining the pH difference on both sides of the middle layer (core layer pH≈9, shell layer pH≈8.0), achieving partitioned buffering.

[0036] 3. Shell coating Taking 100g of shell product as the measurement basis, the formula details of each raw material are as follows: 15g of 3,4-dihydroxyphenylalanine (DOPA) needs to be added, and the molar ratio of 35g of 1H,1H,2H,2H-perfluorodecyl acrylate (FDA) is 4:1; the amount of ammonium persulfate is 0.5g, accounting for 1.0% of the total mass of DOPA and FDA monomers (15g+35g=50g), which is used to initiate the polymerization reaction; 20g of imidazoline corrosion inhibitor is added, and the mass ratio of 5g of hexadecyltrimethylammonium bromide (CTAB) is 4:1 to jointly construct a corrosion inhibition and sterilization system; the amount of sodium tungstate is 3g, accounting for 12% of the mass of the corrosion inhibition and sterilization complex composed of imidazoline corrosion inhibitor and CTAB (20g+5g=25g).

[0037] Step C1: DOPA (15 g) and FDA (35 g) were dissolved in Tris-HCl buffer (200 mL) at pH 8.5, and ammonium persulfate (0.5 g) was added. After nitrogen flow for 10 min, the mixture was reacted at 60°C for 4 h to obtain a copolymer solution.

[0038] Reaction mechanism: Ammonium persulfate initiates free radical copolymerization of the carbon-carbon double bonds of DOPA and FDA to form a DOPA-FDA copolymer. The phenolic hydroxyl group (-OH) of DOPA imparts two key properties to the copolymer: first, strong adhesion to metal surfaces (similar to mussel adhesive protein); second, pH responsiveness—at pH ≥ 8.5, the phenolic hydroxyl group ionizes to -O - The molecular chain stretches, causing the copolymer to swell. The perfluoroalkyl chains of FDA enhance the hydrophobicity of the copolymer, improving its erosion resistance in high-salt seawater environments.

[0039] Step C2: Dissolve imidazoline (20 g), CTAB (5 g), and sodium tungstate (3 g) in 50 mL of ethanol, mix with DOPA-FDA copolymer solution (200 mL), spray onto the surface of the core-intermediate layer composite microspheres by a spray process (pressure 0.3 MPa), and cure under nitrogen protection at 70°C for 12 h to obtain the finished product.

[0040] Reaction mechanism: Imidazoline combines with the copolymer through hydrophobic interaction. When the pH is ≥8.5, the copolymer swells (porosity > 20%), releasing imidazoline and forming an adsorption film on the metal surface through its polar group (-NH—), blocking chloride ion corrosion. The quaternary ammonium group (-N + (CH3)3) binds to the negative charge of bacterial cell membrane, destroying the membrane structure (killing bacteria); Sodium tungstate (WO4 2- ) Protects through a dual mechanism: (1) With metal ions (such as Fe 2+ ) Forming an insoluble precipitation film to inhibit pitting corrosion; (2) Its anion WO4 2-Complexing Ca in seawater 2+ Mg 2+ Plasma interferes with the growth of calcium carbonate / calcium sulfate lattice and inhibits inorganic salt scaling (according to HG / T3778-2005 standard).

[0041] Specifically, in the pH 8.0–8.5 partitioned environment maintained by dynamic boronate bonds in the middle layer: The corrosion inhibition and scale inhibition dual functions of sodium tungstate can be stably and efficiently exerted without being interfered by the strong alkalinity of the core layer (pH≈9); compared with traditional compound reagents (pH8.5-9 compromise range), its scale inhibition efficiency is increased by more than 40% (because too strong alkalinity will cause WO4 2- With Ca 2+ The solubility of the precipitated FeWO4 membrane is lower in a weakly alkaline environment, and the life of the protective membrane is extended to 2.3 times that of the traditional solution.

[0042] All tests are carried out in accordance with international / industry standards: Corrosion inhibition rate: According to GB / T18175-2014 Determination of corrosion inhibition performance of water treatment agents - Rotating coupon method Oxygen removal rate: According to "ASTM D888-18 Test method for dissolved oxygen in water" Bactericidal rate: According to "NACETM0194-2014 Oilfield Water Injection Bactericide Efficacy Evaluation" pH buffer capacity: According to the potentiometric titration method of GB / T9724-2007 General Rules for Determination of pH Value of Chemical Reagents

[0043] Example 1 In the basic scheme, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam in the core layer is 3.0:1, 40g of sodium isoascorbate is loaded, of which the copper-L-histidine complex accounts for 10% of the weight of the oxygen scavenger (i.e., 4g), and the reaction is carried out at 60°C for 24 hours; the molar ratio of 3-aminophenylboronic acid to catechol in the middle layer is 1:1, and silica nanoparticles with a particle size of 50nm are dispersed in aqueous ethanol (volume 100g) under acidic conditions of pH ≈ 4.5. In the reaction mixture, sodium carbonate (2 g) 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., 20.5 g:5 g), and sodium tungstate accounted for 12% (i.e., 3.06 g) of the mass of the corrosion-inhibiting and bactericidal composite. The composite was cured at 70°C and 0.3 MPa for 12 hours.

[0044] Performance tests show that the oxygen removal rate reaches 96.8% in 4 hours at 25°C, the corrosion inhibition rate is 95.2% in 30 days at 25°C, the sulfate-reducing bacteria killing rate reaches 99.9% in 7 days, the buffering 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 by the hanging drop method), and the membrane life exceeds 90 days at a flow rate of 2 m / s (tested by the weight loss method).

[0045] Example 2: For the low-ratio boundary scheme, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam in the core layer was adjusted to 2.8:1, the molar ratio of 3-aminophenylboronic acid to catechol in the middle layer was 1:0.95, the molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate in the shell layer was 4.0:1, and the mass ratio of imidazoline to hexadecyltrimethylammonium bromide was 4.0:1.

[0046] Key performance tests showed that the 4-hour oxygen removal rate at 30°C was 94.3%, a decrease of 2.5% compared with Example 1, mainly due to the reduced proportion of N-vinylcaprolactam; the buffer capacity in the pH range of 8.0-8.5 was 0.142 mol / pH, a decrease of 8.4% compared with Example 1, due to insufficient use of catechol; the shell contact angle was 105°, a decrease of 7° compared with Example 1, which was related to the reduced proportion of 1H,1H,2H,2H-perfluorodecyl acrylate.

[0047] Example 3: For the high-ratio boundary scheme, the molar ratio of 2-acrylamido-2-methylpropanesulfonic acid to N-vinylcaprolactam in the core layer was adjusted to 3.2:1, the molar ratio of 3,4-dihydroxyphenylalanine to 1H,1H,2H,2H-perfluorodecyl acrylate in the shell layer was 4.2:1, and the mass ratio of imidazoline to hexadecyltrimethylammonium bromide was 4.2:1.

[0048] Key performance tests showed that the corrosion inhibition rate was 93.7% at 40°C, a decrease of 1.5% compared with Example 1, due to the enhanced hydrophilicity of 2-acrylamido-2-methylpropanesulfonic acid; the shell contact angle was 118°, an increase of 6° compared with Example 1, thanks to the increased proportion of 1H,1H,2H,2H-perfluorodecyl acrylate; the shedding rate was 2.8% at a high flow rate of 3 m / s, and the anti-scouring performance was optimized.

[0049] Example 4: For extreme working conditions of high salt and high temperature, the corrosive medium is an environment with a chloride ion concentration of 45,000 mg / L, a temperature of 45°C, and a flow rate of 3 m / s. The proportion of copper-L-histidine complex in the core layer increases 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.

[0050] Extreme performance tests showed that the 30-day corrosion inhibition rate reached 92.3%, far higher than the ≤70% of the traditional solution; the oxygen removal half-life was 48 hours at 45°C, significantly longer than the ≤12 hours of the nitrite solution; the shell swelling rate was 58% at pH 8.5, lower than the >85% of the polydopamine solution; and the dynamic bond storage modulus G' at 45°C was 1.1×10 4 Pa, which is much higher than the ≤10³Pa of the physical adsorption layer.

[0051] Comparative Example 1: The traditional compounding scheme directly mixes 40g sodium nitrite, 20g imidazoline, 5g hexadecyltrimethylammonium bromide and 3g sodium tungstate, without a core-shell structure and temperature control process.

[0052] Performance tests showed that at pH 8.5, the corrosion inhibition rate was only 68.2%, a decrease of 27.0% compared with Example 1; at pH 9.0, the imidazoline hydrolysis rate reached 31.6%, an increase of 26.6% compared with Example 1; the sulfate-reducing bacteria killing rate was 85%, a decrease of 14.9% compared with Example 1, highlighting the performance defects of the traditional solution due to the non-partitioned design.

[0053] Comparative Example 2: In the scheme lacking the intermediate layer, the formula of the core layer and the shell layer is the same as that of Example 1, but the core layer and the shell layer are in direct contact with each other, and no intermediate buffer layer is provided.

[0054] Performance tests show that the corrosion inhibition rate fluctuates by ±18.5% in the pH range of 7-9 due to the mutual penetration of the core-shell pH; the corrosion inhibition rate is only 69.5% at 40°C, and the temperature accelerates the hydrolysis of the corrosion inhibitor; the membrane life is only 18 days at a flow rate of 2m / s, due to the lack of intermediate layer protection, resulting in insufficient structural stability.

[0055] Comparative Example 3: In the solution in which 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 the middle layer are the same as those in Example 1.

[0056] Performance tests show that at pH 8.5, the 24-hour corrosion inhibitor release rate is only 15%, a decrease of 77% compared with Example 1; the 30-day corrosion inhibition rate is 72.4%, a decrease of 22.8% compared with Example 1; the shell contact angle is 82°, a decrease of 30° compared with Example 1. The corrosion inhibition film is easy to fall off due to the enhanced hydrophilicity.

[0057] Comparative Example 4: 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 bonds), and the core layer is consistent with Example 1.

[0058] Performance tests show that the shell's resistance to seawater erosion is significantly reduced, the pH buffer capacity of the intermediate layer is less than 50% of that in Example 1, and the 30-day corrosion inhibition rate is more than 25% lower than that in Example 1, confirming the necessity of the dynamic bonding and core-shell coordinated design of the present invention.

[0059] The solid deoxygenation, sterilization, corrosion inhibition and scale inhibitors prepared in Examples 1, 2, 3 and 4 and Comparative Examples 1, 2, 3 and 4 were used as test samples and numbered HSJ1001, HSJ1002, HSJ1003, HSJ1004, HSJ1005, HSJ1006, HSJ1007 and HSJ1008 respectively.

[0060] Product effect testing 1. Corrosion inhibition rate test at different temperatures Corrosive medium conditions: The total mineralization is set to 35000 mg / L, with the ion composition accurately matching the marine environment, including Na + 10770mg / L, Cl - 19350mg / L, Mg 2+ 1290mg / L, Ca 2+ 410mg / L, SO4 2- 2710mg / L, HCO3 - 140mg / L; Simultaneously simulate the dissolved oxygen state of the seawater surface, control the dissolved oxygen concentration to 8mg / L, and add sulfate-reducing bacteria (SRB, concentration 10 5 CFU / mL), iron bacteria (concentration 10 4 CFU / mL) compound system to restore the bio-corrosion scenario faced by seawater pipelines; Experimental parameters: Q235 carbon steel test pieces (size 20mm×20mm×3mm, pre-treated with oil and rust removal) commonly used in seawater pipelines were selected. A 7-day corrosion cycle was used to simulate long-term pipeline operation. A rotating coupon instrument was used to control the speed to 100r / min to reproduce the shear force of seawater flow. Temperature gradients of 10°C, 20°C, 30°C, and 40°C were set to cover seasonal seawater temperature changes and local pipeline temperature increases. This was done to comprehensively test the protective effectiveness of the corrosion inhibitor under temperature variables.

[0061] Test method: The solid deoxygenating, sterilizing, corrosion and scale inhibitors 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 the corrosion inhibitor added. The results are shown in Table 1.

[0062] Table 1: Corrosion inhibition rate at different temperatures (%)

[0063] The corrosion inhibition rates of Examples 1 to 3 remain above 92% within the range of 10-40°C, with a fluctuation range of ≤4.2%. The core of this is the temperature-sensitive synergistic effect of the core layer 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam copolymer hydrogel. The lower critical solution temperature (LCST) of N-vinylcaprolactam adapts to seawater temperature fluctuations. At low temperatures (10-20°C), the hydrogel has a high swelling degree, ensuring the efficient release and deoxygenation of sodium isoascorbate. At high temperatures (30-40°C), it shrinks moderately, reducing the ineffective loss of the oxygen scavenger. At the same time, the buffering effect of the dynamic borate ester bond in the middle layer (buffering capacity 0.14-0.16 mol / pH in the pH range of 8.0-8.5) stabilizes the shell microenvironment, inhibits the hydrolysis of imidazoline, and ensures that the corrosion inhibition function is not affected by drastic temperature changes.

[0064] In Example 4, under extreme working conditions of high salt (Cl⁻=45000 mg / L) and high temperature (40°C), 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 deoxygenation efficiency, and the 1H,1H,2H,2H-perfluorodecyl acrylate component in the shell layer improved the hydrophobicity, resisted the penetration and erosion of high salt solutions, and maintained the structural integrity.

[0065] In comparative example 1 (traditional compounding), due to the lack of core-shell and temperature-sensitive design, the increase in temperature (40°C compared to 10°C) leads to accelerated nitrite decomposition, the imidazoline hydrolysis rate rises to 31.6%, and the corrosion inhibition rate drops sharply by 12.5%; in comparative example 2 (missing intermediate layer), the core-shell pH directly interpenetrates, and high temperature aggravates the hydrolysis of the corrosion inhibitor, and the corrosion inhibition rate at 40°C is only 69.5%; in comparative example 3 (no pH-responsive shell layer), the corrosion inhibitor cannot be released on demand, the protective film is not formed in time at high temperature, and the corrosion inhibition rate continues to decrease with increasing temperature; in comparative example 4 (patent reproduction), due to the lack of dynamic buffering and temperature-sensitive synergy, the structural stability is poor, and the corrosion inhibition rate at 40°C is 32.6% lower than that of Example 1, verifying the key role of the core-shell-dynamic bond-temperature-sensitive synergistic design of the present invention in wide temperature range stability.

[0066] 2. Anti-corrosion effect test under different seawater pH Corrosive medium conditions: Same as the basic formula of "different temperature test", adjust the pH to 7.0 (acidic contaminated seawater), 8.0 (natural seawater pH), 9.0 (alkaline working conditions), 10.0 (extreme alkalinity), and keep other parameters (dissolved oxygen, microorganisms, mineralization) unchanged.

[0067] Experimental parameters: 25°C was selected as the test temperature to match the normal characteristics of the annual average temperature of seawater. A 7-day corrosion cycle was set to simulate the process of continuous erosion by corrosive media during long-term pipeline operation. The rotation speed of the rotary coupon was controlled at 100 r / min to reproduce the shear force effect of seawater flow on the inner wall of the pipeline. The corrosion inhibitor addition amount was maintained at 0.5g / L (consistent with the previous test system) to ensure the single variable principle, thereby accurately verifying the corrosion resistance and long-term effectiveness of the corrosion inhibitor under stable environmental conditions.

[0068] Test method: The pH of the corrosive medium was adjusted by hydrochloric acid / sodium hydroxide, and the corrosion inhibition rate of the steel sheet and the hydrolysis rate of imidazoline 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.

[0069] Table 2: Corrosion inhibition rate (%) and imidazoline hydrolysis rate (%) at different seawater pH

[0070] Example 1 In a medium environment of pH 7.0-10.0, the corrosion inhibition rate is stable at 93.2%-96.5%, and the imidazoline hydrolysis rate is always less than 5%. The core comes from the coordinated regulation of the dynamic boronate bond in the middle layer and the pH-responsive structure of the shell layer - the dynamic bond formed by 3-aminophenylboronic acid and catechol in the middle layer has a buffer capacity of 0.14-0.16 mol / pH in the pH range of 8.0-8.5, and can accurately isolate the pH environment of the core layer and the shell layer by 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 can still be stable at 8.0-8.5 (the stable range of imidazoline corrosion inhibitor), avoiding The alkalinity of the core layer (pH≈9) does not require direct corrosion of the shell imidazoline. At the same time, the shell 3,4-dihydroxyphenylalanine and 1H,1H,2H,2H-perfluorodecyl acrylate copolymer is sensitive to the overall pH of the medium. When the medium pH is ≥8.5 (such as natural seawater or alkaline working conditions), the copolymer swells due to the ionization of phenolic hydroxyl groups (swelling rate 55-70%, porosity >20%), and directionally releases imidazoline to the pipeline surface to form a protective film. At this time, the pH of the shell microenvironment is still maintained at 8.0-8.5, ensuring the stability of the released imidazoline molecular structure, thus resolving the contradiction between "the need to release corrosion inhibitors under high pH of the medium" and "imidazoline is easily hydrolyzed at high pH".

[0071] Example 4 still maintains a release rate of 64.5% and a low hydrolysis rate of 5.8% under extreme alkalinity (pH 10.0) because the increased proportion of the copper-L-histidine complex in the core layer (15%) enhances the deoxygenation efficiency, and the perfluorinated component in the shell layer improves the alkali resistance, offsetting the erosion of the structure by high pH.

[0072] In Comparative Example 1 (traditional compounding), due to the lack of partitioning design, the increase in pH causes the hydrolysis rate of imidazoline to increase from 22.3% (pH 7.0) to 38.5% (pH 10.0), and the corrosion inhibition rate decreases by 23.8% with pH fluctuations; in Comparative Example 4 (patented reproduction), since the middle layer is physically mixed borax (no dynamic buffering) and the shell layer lacks a pH-responsive copolymer, the release rate is only 59.8% at pH 8.5 and the hydrolysis rate reaches 28.7%, verifying the key value of the dynamic bonding and pH-responsive collaborative design of the present invention for stability over a wide pH range.

[0073] By testing the data of these four test samples, it is possible to cover normal working conditions (pH 7.0-10.0) and extreme alkaline environments (pH 10.0), verifying the universality of the technology. Other embodiments / comparative examples (such as Examples 2 and 3 or Comparative Examples 2 and 3) are local parameter adjustment experiments, and their performance differences are implicit in the core comparison and do not need to be expanded separately.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A solid deoxidizing, sterilizing, corrosion inhibiting and scale inhibitor for seawater oil well pipelines, characterized in that: Consists of three-layer core-shell structure: The core layer is 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 is loaded with sodium erythorbate and a copper-L-histidine complex, wherein the copper-L-histidine complex accounts for 5-15% of the mass of the sodium erythorbate; The middle layer is composed of 3-aminophenylboronic acid functionalized silica nanoparticles and catechol connected by dynamic boronate bonds, wherein the molar ratio of 3-aminophenylboronic acid to catechol is 1:0.95-1.05, and the silica nanoparticles have a particle size of 45-55 nm; Shell: It is composed of a corrosion-inhibiting and bactericidal composite 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, and the corrosion-inhibiting and bactericidal composite includes an 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 composite.

2. The solid deoxygenation, sterilization, corrosion inhibition and scale inhibitor for seawater oil well pipelines according to claim 1, characterized in that: 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.

3. The solid deoxygenating, sterilizing, corrosion inhibiting and scale inhibitor for seawater oil well pipelines according to claim 1, characterized in that: The buffer capacity of the dynamic boronate bond in the middle layer is 0.14-0.16 mol / pH in the pH range of 8.0-8.

5.

4. The solid deoxygenation, sterilization, corrosion inhibition and scale inhibitor for seawater oil well pipelines according to claim 1, characterized in that: The shell layer 3,4-dihydroxyphenylalanine-1H,1H,2H,2H-perfluorodecyl acrylate copolymer has a swelling rate of 55-70% at a pH of ≥8.5 and a porosity of >20%.

5. A method for producing a solid deoxidizing, sterilizing, corrosion inhibiting and scale inhibitor for seawater oil well pipelines according to any one of claims 1 to 4, characterized in that: The following steps are involved: A. Nuclear lamina preparation: A1: Dissolve 2-acrylamido-2-methylpropanesulfonic acid and N-vinylcaprolactam in deionized water at a molar ratio of 2.8-3.2:1, add N,N'-methylenebisacrylamide crosslinker and ammonium persulfate initiator, and react at 60°C under nitrogen for 24 hours to form hydrogel microspheres; A2: Immersing the microspheres in a solution containing sodium isoascorbate and copper-L-histidine complex and vacuum drying to obtain a core layer loaded with oxygen scavengers; B. Middle layer modification: B1: Disperse silica nanoparticles in ethanol, add 3-aminopropyltriethoxysilane, and reflux at 70-80°C for 4-6 hours to obtain amino SiO2; B2: Amination of SiO2 and 3-aminophenylboronic acid in acidic conditions (pH ≈ 4.5) in aqueous ethanol solvent, followed by the addition of catechol, and reaction 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 were dissolved in a Tris-HCl buffer solution at a molar ratio of 4.0-4.2:1 at pH 8.5, and ammonium persulfate was added. The mixture was polymerized at 60°C under nitrogen protection for 3-5 hours to obtain a copolymer solution. C2: imidazoline, hexadecyltrimethylammonium bromide, and sodium tungstate were mixed in proportion, sprayed together with the copolymer solution onto the surface of the intermediate layer, and cured at 70° C. for 12 hours to form a shell layer.

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

7. The manufacturing method according to claim 5, characterized in that: In step B2, the molar ratio of 3-aminophenylboronic acid to catechol is 1:1, and the reaction temperature is 30°C.

8. The manufacturing method according to claim 5, characterized in that: The spray pressure in C2 is 0.25-0.35 MPa, and the curing temperature is 70°C.

Images