Temperature-resistant nano-corrosion inhibitor, preparation method and application thereof

Abstract

The present disclosure belongs to the technical field of oil and gas exploration and development, and provides a temperature-resistant nano corrosion inhibitor, a preparation method and application thereof. The corrosion inhibitor comprises rigid aromatic heterocycle modified carbon quantum dots, specifically 2-(4-aminophenyl)benzimidazole covalently grafted modified carbon quantum dots, a non-ionic surfactant, a dispersion stabilizer and water. The preparation method comprises dispersing the rigid aromatic heterocycle modified carbon quantum dots in water, adding the non-ionic surfactant and the dispersion stabilizer, and then aging and vacuum defoaming to obtain the corrosion inhibitor. The corrosion inhibitor is also used for metal member corrosion prevention in any one of the following: ultra-deep oil and gas exploitation, sulfur-containing gas reservoir exploitation, reservoir reconstruction construction, multiphase fluid conveying pipe network and geothermal resource development. The corrosion inhibitor effectively solves the problems of traditional corrosion inhibitors, such as high-temperature degradation, easy desorption and easy fouling, improves the stability, anti-washing property and comprehensive protection efficiency of the corrosion inhibitor system, adapts to extreme industrial corrosion prevention scenes and prolongs the service life of the metal member.

Description

Technical Field

[0001] This disclosure relates to the field of oil and gas exploration and development technology, and in particular to a temperature-resistant nano-corrosion inhibitor, its preparation method, and its application. Background Technology

[0002] Global oil and gas resource development continues to advance into deeper and ultra-deep formations, making downhole operating environments increasingly extreme and demanding. Temperatures exceeding 200°C, acidic media with high H2S / CO2 content, and the scouring effects of ultra-high salinity formation water and high-velocity fluids have become the core challenges for corrosion protection of wellbore tubing in ultra-deep wells. Deep reservoir temperatures generally reach 200-220°C. The combined effects of high-temperature thermodynamics and strong fluid shear accelerate the desorption and rupture of corrosion-inhibiting films, leading to the rapid failure of conventional anti-corrosion systems and seriously threatening the safe operation and long-term stable production of oil and gas well tubing.

[0003] Current high-temperature corrosion inhibitor technology faces significant bottlenecks. Traditional organic corrosion inhibitors (such as imidazoline-based inhibitors) are prone to thermo-oxidative degradation at temperatures exceeding 200°C, leading to a sharp decline in their corrosion inhibition performance due to molecular structure destruction. While some compound systems incorporate inorganic salt additives such as polyphosphates, which may improve corrosion inhibition in the short term, they are highly susceptible to hydrolysis and scaling in high-temperature, high-calcium- and magnesium-ion-rich environments, causing secondary damage such as formation blockage and failing to meet the requirements for long-term protection.

[0004] Nanomaterials offer a new path for upgrading high-temperature corrosion inhibition performance. Carbon dots and other nano-substrates, with their high specific surface area, good dispersibility, and structural tunability, have become a hot topic in the research and development of novel corrosion inhibitors. However, most current nano-corrosion inhibitors use flexible aliphatic hydrocarbon long chains to modify the surface of carbon dots. These flexible chains are prone to curling and breaking under intense thermal motion above 200°C, causing the corrosion inhibition film to collapse rapidly. The effective working temperature can only be maintained at around 90°C, which is completely unsuitable for the extreme working conditions of ultra-deep geothermal environments at 220°C. Furthermore, physically blended or electrostatically adsorbed nano-corrosion inhibitors are prone to functional unit desorption and desorption under high-flow-rate scouring, resulting in poor film stability and difficulty in achieving long-term protection.

[0005] In summary, current corrosion inhibitors generally suffer from fatal defects such as easy degradation at high temperatures, failure of flexible chains, high-temperature hydrolysis and scaling, and weak erosion resistance. There is a lack of nanocomposite corrosion inhibitor systems that combine chemical stability, dense protection, and phosphorus-free environmental protection under combined conditions of extreme high temperature (220℃), high H2S / CO2 content, ultra-high mineralization, and high flow rate erosion. This has become a key technical bottleneck restricting the efficient and safe development of ultra-deep oil and gas, and there is an urgent need to develop a new generation of high-temperature resistant nano-corrosion inhibitors to overcome application limitations. Summary of the Invention

[0006] This disclosure provides a temperature-resistant nano-corrosion inhibitor, its preparation method, and its application, in order to at least solve the above-mentioned technical problems existing in the prior art.

[0007] According to a first aspect of this disclosure, a temperature-resistant nano-corrosion inhibitor is provided, comprising, by mass percentage, 5% to 15% rigid aromatic heterocyclic modified carbon quantum dots, 2% to 8% nonionic surfactant, 1% to 3% dispersant stabilizer, and the balance being water; wherein the rigid aromatic heterocyclic modified carbon quantum dots are 2-(4-aminophenyl)benzimidazole covalently grafted modified carbon quantum dots.

[0008] Specifically, this disclosure uses 2-(4-aminophenyl)benzimidazole covalently grafted modified carbon quantum dots as the core, where 2-(4-aminophenyl)benzimidazole belongs to a rigid aromatic heterocyclic structure. The carbon quantum dots provide a high-density physical shielding effect, and the heteroatoms in 2-(4-aminophenyl)benzimidazole form strong multi-center coordination bonds with iron atoms on the metal surface. Together, they construct an extremely dense inorganic-organic hybrid nanoarmor in situ at the metal interface. The accompanying nonionic surfactant, due to its nonionic properties, is not prone to salting out in high-temperature, high-salt environments, significantly reducing the surface tension of the system and facilitating the rapid spreading and deep penetration of the carbon nanoarmor at the metal interface. The dispersant stabilizer, through both steric hindrance and electrostatic repulsion, effectively prevents the risk of salting out and agglomeration of the nanocarbon dots in highly salinized formation water. The synergistic effect of each component not only improves the thermodynamic stability of the system under extreme high temperature of 220℃ and high H2S / CO2 content, but also effectively avoids the fatal shortcomings of traditional corrosion inhibitor films such as easy desorption, damage and inorganic salt scaling under extremely high flow rate scouring. Finally, through the full-chain synergy of multi-center anchoring, physical shielding and dynamic shear resistance, the safe service life of ultra-deep well tubing is greatly extended, and it has strong industrial applicability and adaptability.

[0009] In one embodiment, the general chemical formula of the rigid aromatic heterocyclic modified carbon quantum dots is as follows: CQDs-(L-Bz)_k; wherein, CQDs is a carbon quantum dot, L is an amide group or an imine group, Bz is 2-(4-aminophenyl)benzimidazole, and k is the grafting density of 2-(4-aminophenyl)benzimidazole.

[0010] Specifically, the surface of CQDs has activated functional groups, which serve as a corrosion-resistant substrate with ultra-high specific surface area and good dispersibility; L is a covalent bridging group used to firmly anchor functional molecules to the carbon quantum dot surface; Bz is the core corrosion-resistant functional unit, which aims to significantly improve the chemical adsorption stability of the molecule at an extreme high temperature of 220℃ by utilizing the strong electron donor-acceptor ability of the heterocyclic conjugated system.

[0011] Specifically, the CQDs are selected from graphitized carbon quantum dots.

[0012] Specifically, the nitrogen-to-carbon ratio (N / C) in the rigid aromatic heterocyclic modified carbon quantum dots is 0.05~0.15. This ensures sufficient rigid heterocyclic coverage on the carbon quantum dot surface.

[0013] This disclosure ensures that the system does not undergo hydrolytic shedding of functional groups under extreme deep-well conditions by atomically covalently assembling nano-substrates and heterocyclic ligands. This completely eliminates the risk of thermo-oxidative degradation of traditional organic anticorrosive films under high-temperature conditions from the molecular level, thereby guaranteeing the absolute chemical stability of the agent for long-term service.

[0014] The aforementioned core agent completely abandons the flexible aliphatic hydrocarbon long chains in traditional corrosion inhibitors, which are prone to thermal and oxidative degradation and chain breakage of carbon-carbon bonds. It innovatively introduces 2-(4-aminophenyl)benzimidazole, which has a thermal decomposition temperature greater than 300℃. While retaining the excellent coordination advantages of heterocyclic compounds with metals, it effectively solves the shortcomings of conventional small-molecule organic corrosion inhibitors, which are prone to film rupture and desorption under high temperature and high shear fluid scouring above 200℃. The upper limit of temperature resistance reaches 220℃. Moreover, the huge steric hindrance effect of nano-carbon quantum dots greatly increases the diffusion path of corrosive media to penetrate into the metal substrate. Without relying on inorganic polyphosphates that are prone to hydrolysis and scaling, it can reduce the corrosion rate under extremely high salinity to below the safe threshold in situ, perfectly adapting to the corrosion prevention needs of complex oil and gas wells with high salinity and ultra-deep formations.

[0015] In one embodiment, the nonionic surfactant is selected from at least one of alkyl glycosides, fatty alcohol polyoxyethylene ethers, polyethers, and sorbitan fatty acid esters.

[0016] Specifically, the role of nonionic surfactants is to: (1) reduce the interfacial tension of the aqueous system, improve the wettability of the system, and help the corrosion inhibitor components to reach the metal surface quickly; (2) promote the uniform spreading and tight arrangement of rigid aromatic heterocyclic modified carbon quantum dots at the metal interface to form a denser protective film; (3) improve the dispersion stability of nano carbon quantum dots in high-mineralization formation water and reduce agglomeration; (4) not salt out or degrade under high temperature conditions, and work synergistically with the corrosion inhibitor to improve the high temperature corrosion inhibition efficiency and long-term effectiveness.

[0017] In one embodiment, the dispersant stabilizer is selected from at least one of lignin sulfonate, sulfonated acetone-formaldehyde condensate, polycarboxylate, and sulfomethylphenol resin.

[0018] Specifically, the dispersant stabilizer can form steric hindrance and electrostatic repulsion on the surface of nano-carbon quantum dots, preventing nanoparticles from agglomerating, settling or salting out in high temperature, high salt and high calcium and magnesium ion environments, ensuring that the corrosion inhibitor remains uniform and stable in extreme downhole environments, and ensuring the continuous construction of a dense protective film.

[0019] According to a second aspect of this disclosure, a method for preparing the above-mentioned temperature-resistant nano-corrosion inhibitor is provided, comprising the following steps: Rigid aromatic heterocyclic modified carbon quantum dots were dispersed in water, and nonionic surfactants and dispersants were added. After aging and vacuum degassing, the heat-resistant nano corrosion inhibitor was obtained. The rigid aromatic heterocyclic modified carbon quantum dots are 2-(4-aminophenyl)benzimidazole covalently grafted modified carbon quantum dots.

[0020] In one embodiment, the rigid aromatic heterocyclic modified carbon quantum dots are prepared by covalent bonding reaction of carbon quantum dots with active functional groups on their surface and 2-(4-aminophenyl)benzimidazole.

[0021] In a preferred embodiment, the rigid aromatic heterocyclic modified carbon quantum dots are prepared by amidation reaction of covalently grafting 2-(4-aminophenyl)benzimidazole onto the surface of graphitized carbon quantum dots containing carboxyl groups, followed by dialysis and freeze-drying.

[0022] Specifically, using classic amidation coupling technology, 2-(4-aminophenyl)benzimidazole, which possesses extremely strong temperature resistance and corrosion resistance, is grafted onto the surface of carbon quantum dots through robust covalent amide bonds. Compared to fragile physical mixing and adsorption, covalent grafting fundamentally prevents the desorption and release of the corrosion-resistant functional unit under high-temperature hydrothermal conditions, ensuring the consistency and long-term stability of the composite nanomaterial structure. Simultaneously, the post-processing of dialysis and freeze-drying thoroughly removes unreacted small molecule monomers and byproducts, improving the purity and interfacial activity of the core active ingredient.

[0023] In one embodiment, the rigid aromatic heterocyclic modified carbon quantum dots are dispersed in 75% to 85% water; the dispersion is performed by ultrasonic dispersion, with an ultrasonic power of 800 to 1000 W, an ultrasonic dispersion temperature of 25 to 28°C, and an ultrasonic dispersion time of 25 to 35 min.

[0024] In one embodiment, the nonionic surfactant is added at a rotation speed of 200-400 r / min and mixed for 20-40 min; then the dispersion stabilizer is added at a rotation speed of 200-400 r / min.

[0025] In one embodiment, the curing speed is 500~700 r / min, the temperature is 40~50℃, and the time is 1~2 h.

[0026] After the above isothermal shearing and curing process, the components are fully associated at the molecular level.

[0027] In one embodiment, the vacuum degree of the vacuum degassing is -0.08 to -0.06 MPa, and the time is 1 to 2 hours.

[0028] In one embodiment, the heat-resistant nano-corrosion inhibitor is obtained by filtering impurities after vacuum degassing.

[0029] Specifically, this disclosure first employs high-power ultrasonic dispersion technology to treat the core nano-agent, effectively overcoming the van der Waals aggregation phenomenon that easily occurs in nano-carbon materials at high concentrations, thus laying a uniform thermodynamic foundation for subsequent multi-component formulation. Subsequently, surfactants and dispersing stabilizers are introduced at appropriate rotation speeds, supplemented by a constant-temperature high-shear curing process, driving the polymeric stabilizer to form an effective steric adsorption layer on the carbon quantum dot surface, pre-constructing a physical microenvironment that prevents salt accumulation and aggregation. Finally, vacuum degassing removes microbubbles from the system to avoid oxidative degradation under the high-pressure environment of deep wells. The entire process ensures both the structural stability and high dispersion uniformity of the nanocomposite system, while also strengthening the core efficacy of the agent in achieving extremely high mineralization and preventing salt precipitation and high-temperature sedimentation from the bottom layer. It is fully adaptable to the harsh formation water environment of tight deep oil and gas wells, possessing both precise process controllability and industrial feasibility for large-scale factory production.

[0030] According to the third aspect of this disclosure, the above-mentioned temperature-resistant nano corrosion inhibitor is provided for corrosion protection of metal components in any of the following fields: ultra-deep oil and gas extraction, sulfur-containing gas reservoir extraction, reservoir stimulation construction, multiphase fluid transportation pipeline network, and geothermal resource development.

[0031] Specifically, the corrosion inhibitor disclosed herein breaks through the thermodynamic limit of 220℃ and the corrosion bottleneck of extremely high flow velocity erosion. It is phosphorus-free and anti-scaling, and can be widely used in: (1) Ultra-deep / extra-deep oil and gas development: suitable for 8000-meter-level high-temperature and high-salt deep wells, providing long-lasting nano-armor for completion tubing and significantly reducing well workover costs. (2) Strongly acidic / high-sulfur gas reservoirs: effectively blocking acid gas penetration in high H2S / CO2 environments and completely eliminating local pitting corrosion. (3) High-temperature reservoir stimulation operations: as an anti-corrosion additive for fracturing fluids or acidizing fluids, resisting extremely high pumping shear and eliminating secondary scaling damage to the formation. (4) Multiphase flow and subsea pipeline network: solving the high-speed erosion-corrosion problem of gas, liquid and solid mixed pipelines. (5) Deep geothermal resource development: cross-border adaptable to the extreme anti-corrosion requirements of complex geothermal brine wells above 200℃.

[0032] According to one possible implementation of this disclosure, at least the following beneficial effects are achieved: 1. This disclosure relies on rigid aromatic heterocyclic modified carbon quantum dots as the core agent, combined with synergistic nonionic surfactants and dispersants to achieve precise formulation and compounding, constructing a nanoscale, full-chain integrated functional synergistic protection system. This system is perfectly adapted to the extremely complex downhole environment in deep oil and gas development scenarios, characterized by extreme high temperatures, enrichment of acidic corrosive media, and coexistence of ultra-high mineralization. It fundamentally avoids three core application problems of traditional organic corrosion inhibitors: high-temperature pyrolysis failure, peeling and detachment of the anti-corrosion film under high-speed fluid scouring, and inorganic salt agglomeration, precipitation, and scaling in high-salt environments. It provides long-term, stable protection of the interface substrate of the entire downhole metal tubing string, significantly extending the continuous safe service life of ultra-deep well completion tubing and downhole metal components, and reducing the overall cost of downhole operation, maintenance, and equipment replacement.

[0033] 2. This disclosure precisely targets the core anti-corrosion substrate optimization design concept, exclusively preparing rigid aromatic heterocyclic modified carbon quantum dots as the core functional agent for all-domain anti-corrosion. It innovatively adopts a high thermal stability phosphorus-free 2-(4-aminophenyl)benzimidazole structure to replace the flexible aliphatic hydrocarbon long-chain substrate suitable for traditional corrosion inhibition systems. This precisely overcomes the inherent technical shortcomings of conventional small-molecule organic corrosion inhibitors, which are prone to thermo-oxidative decomposition and molecular chain hydrolysis under extreme high-temperature conditions. Simultaneously, it fully utilizes the unique high-density interface physical shielding properties of carbon quantum dot nanomaterials to construct a dense, high-strength, bonded nano-protective armor in situ on the metal substrate surface. Even under harsh conditions of extreme high-temperature strong molecular thermal motion disturbance and continuous impact and erosion by high-shear fluids, the protective layer interface can still maintain a regular and dense arrangement, preventing various corrosive media from contacting the metal substrate at the microscopic molecular level, thus building a long-lasting closed-loop anti-corrosion barrier.

[0034] 3. This disclosure employs a classic amidation coupling modification process suitable for industrial mass production to perform directional covalent grafting modification on the surface of carbon quantum dot substrates to prepare an integrated nano-anticorrosion agent. The process is mature and easily scaled up for mass production, meeting the needs of industrial-scale batch preparation. This modification method enables the 2-(4-aminophenyl)benzimidazole anticorrosion functional unit to be anchored and bonded to the surface of carbon quantum dot nanoparticles with high density, uniformity, and stability. Simultaneously, relying on high-strength solid-state covalent bond forces, it completely overcomes the core drawbacks of traditional corrosion inhibition systems—such as simple physical mixing and weak electrostatic adsorption—which are prone to desorption, dissociation, and structural collapse in high-temperature, high-flow-rate downhole fluid environments. This comprehensively enhances the adhesion between the nano-anticorrosion film and the downhole metal substrate interface, simultaneously improving the thermodynamic structural stability of the entire protection system. It endows the overall corrosion inhibition system with excellent resistance to fluid shear and continuous erosion, making it suitable for long-term, uninterrupted downhole operation scenarios.

[0035] 4. This disclosure selects specialized nonionic surfactants and dispersants suitable for specific working conditions, forming a multi-component complementary synergistic effect mechanism with the core nano-anticorrosion substrate, adapting to the needs of downhole applications under all working conditions. On the one hand, relying on the exclusive nonionic interfacial activity characteristics of the additives, the surface tension of the metal substrate interface under high-temperature conditions is effectively reduced, assisting the rigid aromatic heterocyclic modified carbon quantum dot nano-protective units to quickly spread and uniformly adhere to cover the entire metal interface, filling in local protection gaps and dead zones; on the other hand, relying on the additives to synergistically construct a dual microscopic stable protective environment of spatial steric hindrance and electrostatic repulsion, fundamentally preventing the nano-functional substrate from agglomerating, salting out, flocculating, and settling into failure in ultra-high mineralization formation water. It comprehensively improves the overall dispersion uniformity and component compatibility stability of the supramolecular nano-corrosion inhibitor system, and strengthens the comprehensive and long-term anticorrosion service performance of the entire domain, adapting to various extreme industrial anticorrosion application scenarios such as ultra-deep oil and gas and geothermal environments.

[0036] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0037] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0038] Figure 1 A schematic diagram of the synthesis route of benzimidazole-modified carbon quantum dots in Example 1 of this disclosure is shown. Detailed Implementation

[0039] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0040] Unless otherwise specified, all chemical reagents used in the embodiments and comparative examples disclosed herein are commercially available and have a purity of analytical grade AR or higher. Specifically, citric acid and urea, precursors for synthesizing carbon quantum dots, o-phenylenediamine and p-aminobenzaldehyde, raw materials for synthesizing rigid heterocycles, and ethylamidation coupling reagents EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; synergistic nonionic surfactants (alkyl glycoside APG-08) and high-temperature dispersion stabilizers (sodium lignosulfonate) were purchased from Sinopharm Chemical Reagent Co., Ltd.; and inorganic salts (NaCl, CaCl2, MgCl2, etc.) used to simulate formation water, as well as conventional solvents such as anhydrous ethanol, glacial acetic acid, and N,N-dimethylformamide (DMF), were purchased from Aladdin Biochemical Technology Co., Ltd. The oil-based hydroxyethyl imidazoline and dodecyl-modified carbon dots used in the comparative examples were either self-made or custom-made in the laboratory based on existing published literature.

[0041] The core performance evaluation instruments disclosed herein mainly include: the FCY-50 high-temperature and high-pressure dynamic corrosion reactor (Jiangsu Haian Petroleum Scientific Research Instrument Co., Ltd.) for extreme high-temperature erosion testing; the CHI660E electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.) for interface armor tightness testing (EIS impedance); and the polytetrafluoroethylene-lined hydrothermal reactor, the TL-600Y high-power ultrasonic cell disruptor, and the FD-1A-50 vacuum freeze dryer (Beijing Boyikang Experimental Instrument Co., Ltd.) for the synthesis of core main agents.

[0042] Example 1 This embodiment prepares a temperature-resistant nano-corrosion inhibitor, as detailed below: (1) Dissolve 0.1 mol o-phenylenediamine and 0.1 mol p-aminobenzaldehyde in 100 mL of anhydrous ethanol, and add 2 mL of glacial acetic acid as a catalyst. Under nitrogen protection, reflux at 80 °C for 6 h. Then, slowly add saturated sodium bisulfite aqueous solution to carry out the oxidation ring-closure reaction, and stir at constant temperature for 4 h. Pour the product into a large amount of ice water, filter out the precipitate, wash with deionized water and anhydrous ethanol alternately, and dry under vacuum at 60 °C to obtain terminal aminobenzimidazole.

[0043] Weigh 2.0 g of citric acid and 1.0 g of urea, and sonicate them in 20 mL of deionized water. Transfer the precursor solution to a polytetrafluoroethylene-lined reactor and perform a solvothermal reaction at 180 °C for 6 h. After cooling, collect the supernatant by centrifugation at 10000 r / min for 15 min. Dialyze the supernatant in a dialysis bag with a molecular weight cutoff of 500 Da for 48 h, then cool and dry to obtain carbon quantum dot powder rich in surface carboxyl groups.

[0044] The following schematic diagram illustrates the synthesis of benzimidazole-modified carbon quantum dots. Figure 1 As shown, 0.5 g of carbon quantum dot powder rich in surface carboxyl groups was weighed and ultrasonically dispersed in 50 mL of phosphate buffer. 0.4 g of EDC and 0.3 g of NHS were added, and the mixture was stirred at room temperature in the dark for 2 hours for activation. Subsequently, 0.5 g of terminal aminobenzimidazole (i.e.,...) was added... Figure 1 2-(4-aminophenyl)benzimidazole was dissolved in a small amount of DMF and slowly added dropwise to the carbon dot solution. The mixture was stirred vigorously at room temperature for 24 hours. The reaction solution was then placed in a dialysis bag with a molecular weight cutoff of 1000 Da and dialyzed for 72 hours. Finally, it was freeze-dried under vacuum at -50°C to obtain the core agent of benzimidazole-modified carbon quantum dots (CQDs-Bz).

[0045] (2) Slowly add 10g of the core agent benzimidazole modified carbon quantum dots CQDs-Bz obtained in step (1) to 83g of deionized water, and ultrasonically disperse it for 30min at 25℃ using an 800W ultrasonic generator to obtain a monodisperse agent base liquid.

[0046] (3) Under mechanical stirring at 300 r / min, slowly add 5 g of synergistic nonionic surfactant alkyl glycoside APG-08 to the base liquid and stir for 30 min.

[0047] (4) Continue to slowly add 2g of high temperature dispersion stabilizer sodium lignosulfonate, increase the stirring speed to 600r / min, and keep the mixture at 45℃ for 1.5h to obtain a composite dispersion.

[0048] (5) The composite dispersion was subjected to vacuum degassing treatment at a vacuum degree of -0.08MPa for 1h. After filtering out impurities, a uniform and transparent temperature-resistant nano corrosion inhibitor was obtained.

[0049] Example 2 This embodiment prepares a temperature-resistant nano-corrosion inhibitor, and its preparation process is exactly the same as that in Example 1, so it will not be described again here.

[0050] The raw material ratio in this embodiment is as follows: by mass percentage, the core agent is 15%; nonionic surfactant is 2%; high-temperature dispersion stabilizer is 1%; and the remainder is deionized water.

[0051] Example 3 This embodiment prepares a temperature-resistant nano-corrosion inhibitor, and its preparation process is exactly the same as that in Example 1, so it will not be described again here.

[0052] The raw material ratio in this embodiment is as follows: by mass percentage, the core agent is 5%; the nonionic surfactant is 8%; the high-temperature dispersion stabilizer is 3%; and the remainder is deionized water.

[0053] Example 4 This embodiment prepares a temperature-resistant nano-corrosion inhibitor, and its preparation process is exactly the same as that in Example 1, so it will not be described again here.

[0054] The raw material ratio in this embodiment is as follows: by mass percentage, the core agent is 12%; nonionic surfactant is 4%; high-temperature dispersion stabilizer is 2%; and the remainder is deionized water.

[0055] Example 5 This embodiment prepares a temperature-resistant nano-corrosion inhibitor, and its preparation process is exactly the same as that in Example 1, so it will not be described again here.

[0056] The raw material ratio in this embodiment is as follows: by mass percentage, the core agent is 8%; the nonionic surfactant is 6%; the high-temperature dispersion stabilizer is 2%; and the remainder is deionized water.

[0057] Comparative Example 1 This comparative example prepared a temperature-resistant corrosion inhibitor, which was prepared entirely according to Example 2 in the patent document with publication number CN121495562A to obtain a high-temperature resistant corrosion inhibitor and bactericide. It comprises a ternary composite system formed by oil-based hydroxyethyl imidazoline, sodium tripolyphosphate, and a bactericide.

[0058] Comparative Example 2 This comparative example prepared a corrosion inhibitor, which was prepared entirely according to Example 2 in the patent document with publication number CN121653660A. The long carbon chain modified carbon quantum dot corrosion inhibitor contained a CDs-C12 system modified by bromododecane.

[0059] Comparative Example 3 This comparative example prepared a corrosion inhibitor. Unlike Example 1, this comparative example used a conventional high-temperature corrosion inhibitor system commonly used in oil fields. The formula was: 20% imidazoline quaternary ammonium salt, 5% nonionic surfactant, and the balance being deionized water, which was prepared by mechanical stirring.

[0060] Comparative Example 4 This comparative example prepared a corrosion inhibitor. Unlike Example 1, this comparative example is a conventionally physically mixed carbon dot corrosion inhibitor. Its formulation is as follows: by mass percentage, 10% unmodified common carboxyl-rich carbon quantum dots, 5% terminal aminobenzimidazole monomer, 5% nonionic surfactant, 2% high-temperature dispersant, and the balance is deionized water. During preparation, physical mixing was performed only by mechanical stirring and ultrasound; no EDC / NHS was added for covalent coupling.

[0061] Comparative Example 5 This comparative example prepared a corrosion inhibitor. Unlike Example 1, this comparative example did not add a nonionic surfactant, and the missing 5g mass was made up with deionized water. The rest is the same as in Example 1, and will not be repeated here.

[0062] Comparative Example 6 This comparative example prepared a corrosion inhibitor. Unlike Example 1, this comparative example did not include a high-temperature dispersant stabilizer, and the missing 2g mass was made up with deionized water. The rest is the same as in Example 1, and will not be repeated here.

[0063] The corrosion inhibitors of Examples 1-5 and Comparative Examples 1-6 were tested under the following stringent conditions: (1) Extreme high-temperature dynamic corrosion rate: A high-temperature and high-pressure dynamic reactor and the weight loss method were used. The corrosion rate was determined at 220℃, 15MPa, and a simulated formation water salinity of 150,000 mg / L (containing Ca). 2+ / Mg 2+ Under harsh conditions of 5000 mg / L, saturated with 15% CO2 and 0.1% H2S, and a dynamic strip flushing flow rate of 5.0 m / s, 100 mg / L of each group of corrosion inhibitors were added, and the average corrosion rate of N80 steel strips was measured after continuous flushing for 72 h.

[0064] (2) Extreme aging stability: Each group of corrosion inhibitor solutions was placed in a deoxygenated autoclave and aged for 90 days at 220°C. After being taken out, its dynamic corrosion rate was re-measured and the retention rate of corrosion inhibition efficiency was calculated.

[0065] (3) Compactness of the armor film (charge transfer resistance Rt): Using a high-temperature electrochemical workstation, after dynamic rinsing at 220℃ for 72h, the electrochemical impedance (EIS) of the metal interface was measured in situ, and the interface charge transfer resistance Rt value was extracted and calculated.

[0066] (4) High temperature and high calcium and magnesium compatibility scaling: Add each group of reagents to simulated formation water containing 5000 mg / L calcium and magnesium ions at 220℃, and observe whether there is precipitation or scaling in the solution after standing at constant temperature for 24 hours.

[0067] The test results are shown in Table 1.

[0068] Table 1

[0069] Combining Example 1 and Comparative Examples 1-3 and referring to Table 1, it can be seen that although the existing technology has anti-corrosion effect under conventional low and medium temperature conditions, it collectively fails under extreme high temperature of 220℃ and extremely high scouring flow rate of 5.0 m / s. In Comparative Example 1, the organic imidazoline rapidly desorbs thermally, and its polyphosphate undergoes severe hydrolysis and scaling in a high calcium and magnesium environment at 220℃, causing secondary reservoir damage. In Comparative Example 2, the long carbon chain modified carbon quantum dots experience instantaneous film collapse due to the violent curling and breakage of flexible dodecyl groups at high temperatures, with a corrosion rate as high as 0.880 mm / a. In contrast, Example 1, relying on the original benzimidazole-modified carbon dot rigid armor, completely avoids the technical bias of thermo-oxidative degradation and flexible chain failure. Under the same extreme conditions, it reduces the corrosion rate to an extremely low level of 0.035 mm / a, and the all-carbon-based phosphorus-free system completely solves the problem of high calcium and magnesium scaling. After aging for 90 days, the retention rate is as high as 96.5%, achieving a generational performance breakthrough over the existing technology.

[0070] Combining Example 1 and Comparative Example 4 with reference to Table 1, it can be seen that Comparative Example 4, using a simple physical mixing method, under intense thermal motion at 220°C and high-flow-rate scouring, saw the benzimidazole monomers that had not formed chemical bonds with the nano carbon dots rapidly detach from the metal surface and be carried away by the fluid, failing to form a synergistic nano-armor with the carbon dots, resulting in a corrosion rate as high as 0.520 mm / a. This, in turn, confirms the absolute irreplaceability of the covalent grafting process in the embodiments of this disclosure for maintaining the extreme high-temperature stability of the nano armor.

[0071] Combining Example 1 and Comparative Example 5 and referring to Table 1, it can be seen that Example 1, by combining a synergistic nonionic surfactant, utilizes its property of reducing interfacial tension to significantly promote the deep spreading and dense arrangement of rigid nano-armor at the metal interface, achieving an interfacial charge transfer resistance as high as 18500 Ω·cm. 2 In contrast, in Comparative Example 5, the lack of this surfactant resulted in impaired spread of nano-carbon dots at the interface, leading to the formation of penetration channels in the corrosive medium. The corrosion rate rebounded sharply to 0.085 mm / a, exceeding the industry safety threshold of 0.076 mm / a, fully demonstrating the crucial synergistic role of surfactants in assisting in the construction of a dense barrier.

[0072] Combining Example 1 and Comparative Example 6 with reference to Table 1, it can be seen that Example 1 introduced a high-temperature dispersant stabilizer, which provided sufficient steric hindrance for carbon dots in an extremely high salinity environment. However, Comparative Example 6, lacking this stabilizer, experienced significant salt precipitation and aggregation during ultra-long aging at 220℃, leading to a sharp reduction in effective anti-corrosion components and a drop in the aging corrosion inhibition retention rate to 75.5%, thus compromising the later-stage stability of the anti-corrosion film. This confirms the core stabilizing value of dispersant stabilizers in constructing long-lasting salt-resistant defenses and maintaining the thermodynamic stability of nanoscale systems.

[0073] As can be seen from Examples 4 and 5 and Table 1, even with flexible fine-tuning of the concentrations of the main agent and auxiliary agent within a certain range, the corrosion rate of this disclosure remains stable at an excellent level of approximately 0.040 mm / a, with balanced interfacial resistance and aging stability. This fully demonstrates that the formulation system based on rigid heterocyclic grafted carbon quantum dots in this disclosure not only has an advanced mechanism but also possesses extremely high process robustness and feasibility for large-scale industrial application, perfectly adapting to the development needs of extremely deep and harsh working conditions.

[0074] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0075] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0076] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A temperature-resistant nano-corrosion inhibitor, characterized in that, By mass percentage, the temperature-resistant nano-corrosion inhibitor comprises 5% to 15% rigid aromatic heterocyclic modified carbon quantum dots, 2% to 8% nonionic surfactant, 1% to 3% dispersant stabilizer, and the balance being water; the rigid aromatic heterocyclic modified carbon quantum dots are 2-(4-aminophenyl)benzimidazole covalently grafted modified carbon quantum dots.

2. The temperature-resistant nano-corrosion inhibitor according to claim 1, characterized in that, The general chemical formula of the rigid aromatic heterocyclic modified carbon quantum dots is as follows: CQDs-(L-Bz)_k; where CQDs is a carbon quantum dot, L is an amide group or an imine group, Bz is 2-(4-aminophenyl)benzimidazole, and k is the grafting density of 2-(4-aminophenyl)benzimidazole.

3. The temperature-resistant nano-corrosion inhibitor according to claim 1, characterized in that, The nonionic surfactant is selected from at least one of alkyl glycosides, fatty alcohol polyoxyethylene ethers, polyethers, and sorbitan fatty acid esters.

4. The temperature-resistant nano-corrosion inhibitor according to claim 1, characterized in that, The dispersing stabilizer is selected from at least one of lignin sulfonate, sulfonated acetone-formaldehyde condensate, polycarboxylate, and sulfomethylphenol resin.

5. The method for preparing the temperature-resistant nano-corrosion inhibitor according to any one of claims 1 to 4, characterized in that, Includes the following steps: Rigid aromatic heterocyclic modified carbon quantum dots were dispersed in water, and nonionic surfactants and dispersants were added. After aging and vacuum degassing, the heat-resistant nano corrosion inhibitor was obtained. The rigid aromatic heterocyclic modified carbon quantum dots are 2-(4-aminophenyl)benzimidazole covalently grafted modified carbon quantum dots.

6. The preparation method according to claim 5, characterized in that, The rigid aromatic heterocyclic modified carbon quantum dots are prepared by covalent bonding reaction of carbon quantum dots with active functional groups on the surface with 2-(4-aminophenyl)benzimidazole.

7. The preparation method according to claim 5, characterized in that, The rigid aromatic heterocyclic modified carbon quantum dots were dispersed in 75%~85% water; the dispersion was performed by ultrasonic dispersion, with an ultrasonic power of 800~1000W, an ultrasonic dispersion temperature of 25~28℃, and an ultrasonic dispersion time of 25~35min.

8. The preparation method according to claim 5, characterized in that, The nonionic surfactant is added at a rotation speed of 200-400 r / min and mixed for 20-40 min; then the dispersion stabilizer is added at a rotation speed of 200-400 r / min.

9. The preparation method according to claim 5, characterized in that, The ripening process is carried out at a rotation speed of 500~700 r / min, a temperature of 40~50℃, and a time of 1~2 h. The vacuum degassing process is performed at a vacuum level of -0.08 to -0.06 MPa for 1 to 2 hours.

10. The application of the temperature-resistant nano-corrosion inhibitor according to any one of claims 1 to 4, characterized in that, It can be used for corrosion protection of metal components in any of the following fields: ultra-deep oil and gas extraction, sulfur-bearing gas reservoir extraction, reservoir stimulation construction, multiphase fluid transportation pipeline network, and geothermal resource development.

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