High-salt-resistant corrosion-inhibiting nano-impregnating agent, preparation method and application thereof

Abstract

The application provides a high-salt-resistant corrosion-inhibiting nano-imbibition agent, a preparation method and application thereof, and comprises, by weight percentage, 8-12% polyethylene glycol-b-poly caprolactone, 5-10% sodium gluconate, 5-10% cellulose derivative, 0.3% oilfield-grade benzotriazole, 0.6% industrial-grade sodium pyrophosphate, and the rest is a dispersion medium; the cellulose derivative is a cellulose derivative activated by 0.5% silane coupling agent. Thus, the three-dimensional porous network constructed by the activated sodium carboxymethyl cellulose improves the dispersion stability and water-retention imbibition capacity of the system; the polyethylene glycol-b-poly caprolactone reduces the oil-water interfacial tension by virtue of the amphiphilic structure, and accelerates imbibition penetration; the sodium gluconate and sodium pyrophosphate synergistically chelate high-salt ions, and strengthen the salt resistance. In addition, the benzotriazole forms a dense protective film on the metal surface, and in combination with the scale and corrosion inhibition effects of sodium pyrophosphate, efficient corrosion inhibition is achieved.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, and more specifically, to a high-salt corrosion-inhibiting nano-permeable agent, its preparation method, and its application. Background Technology

[0002] In the oil and gas extraction sector, the development of high-salinity reservoirs (typically defined as those with a total formation water salinity exceeding 100,000 mg / L) has become a crucial direction for the efficient utilization of global oil and gas resources. According to petroleum industry statistics, these reservoirs account for over 30% of my country's proven oil and gas reserves, and an even higher proportion in oil and gas-rich regions such as the Middle East and Central Asia. However, due to the unique environment of these reservoirs with high formation water salinity and high corrosive ion content, the extraction process faces challenges such as low percolation efficiency and easy corrosion of metal equipment, thus restricting development efficiency and production safety.

[0003] From the perspective of percolation efficiency, conventional percolators mostly use ordinary nanoparticles or linear polymers as core components, which are prone to aggregation in high-salt environments due to the electrostatic shielding effect of salt ions. For example, percolators using unmodified nano-silica as a carrier exhibit significantly reduced nanoparticle dispersion stability in formation water with salinity exceeding 150,000 mg / L, failing to effectively penetrate into the micropores of the reservoir (the pore diameter in conventional sandstone reservoirs is mostly 50-100 nm). This results in percolation being limited to the near-wellbore zone, significantly reducing the oil stripping and displacement effects. Simultaneously, high-salt environments disrupt the interfacial balance between the percolator, crude oil, and rock, preventing the oil-water interfacial tension from being stably maintained within the low range required for efficient percolation, further reducing the extent of oil recovery.

[0004] In addition, the formation water of high-salinity oil reservoirs is rich in Cl. - Ca 2+ Mg 2+ Corrosive ions, including Cl - Concentrations can often reach over 100,000 mg / L, which can accelerate the electrochemical corrosion of tubing, casing, and oil production equipment, leading to defects such as pitting and stress corrosion cracking, increasing maintenance costs and downtime losses.

[0005] Therefore, there is an urgent need for a nano-permeasurant to solve the problems in the existing technology. Summary of the Invention

[0006] The main objective of this invention is to provide a high-salt corrosion-inhibiting nano-permeabilizer, its preparation method, and its application, so as to at least solve the problems of conventional permeabilizers in high-salt reservoirs being prone to agglomeration, having low permeation efficiency, and lacking effective corrosion inhibition performance.

[0007] To achieve the above objectives, the present invention provides a high-salt corrosion-inhibiting nano-permeable agent, comprising, by weight percentage: 8-12% polyethylene glycol-b-polycaprolactone, 5-10% sodium gluconate, 5-10% nano-sized cellulose derivative, 0.3% oilfield-grade benzotriazole, 0.6% industrial-grade sodium pyrophosphate, with the balance being a dispersion medium, and the sum of the weight percentages of all components being 100%; wherein the cellulose derivative is a cellulose derivative activated by 0.5% by mass of silane coupling agent.

[0008] Optionally, the silane coupling agent is an amino-based silane coupling agent.

[0009] Optionally, the cellulose derivative is sodium carboxymethyl cellulose.

[0010] Optionally, the dispersion medium is deionized water or simulated reservoir brine with a total salinity ≤200,000 mg / L.

[0011] This invention also provides a method for preparing a high-salt-resistant corrosion-inhibiting nano-permeabilizer, which is applied to the high-salt-resistant corrosion-inhibiting nano-permeabilizer described in this invention, comprising the following steps:

[0012] Step 1, Raw material pretreatment: Prepare benzotriazole ethanol solution and sodium pyrophosphate aqueous solution respectively. Activate the cellulose derivative with silane coupling agent. Mix the sodium pyrophosphate aqueous solution with sodium gluconate to obtain a mixed solution.

[0013] Step 2: Constructing a porous suspension: Add the activated cellulose derivative to the dispersion medium, disperse it by ultrasound, and then bubble it with a small amount of nitrogen gas to form a cellulose derivative suspension with a uniform porous structure.

[0014] Step 3, Component Mixing: Under stirring, add benzotriazole ethanol solution, sodium pyrophosphate-sodium gluconate mixture, and polyethylene glycol-b-polycaprolactone to the suspension obtained in Step 2 in sequence, and stir until the mixture is homogeneous;

[0015] Step 4, standing and testing: Let the mixture obtained in step 3 stand for 10 minutes, take a sample and test the pH value to be 6.0~8.0 and the nanoparticle dispersion size ≤30nm, then a qualified high salt corrosion inhibitor nano-permeable agent is obtained.

[0016] Optionally, in step 1, the preparation process of the benzotriazole ethanol solution is as follows: take the formula amount of oilfield-grade benzotriazole, add 3 to 5 times its mass of industrial ethanol, and stir at 25 to 30°C for 10 to 15 minutes until completely dissolved.

[0017] The preparation process of sodium pyrophosphate aqueous solution is as follows: take the formula amount of industrial grade sodium pyrophosphate, add 8 to 10 times its mass of 30℃ warm water, and stir for 5 to 8 minutes until fully dissolved.

[0018] Optionally, in step 1, the cellulose derivative is sodium carboxymethyl cellulose, the silane coupling agent is an amino-based silane coupling agent, and the process of activating the cellulose derivative with the silane coupling agent is as follows:

[0019] Take the prescribed amount of sodium carboxymethyl cellulose, add 5-8 times its mass of deionized water, and ultrasonically create pores for 15-20 minutes at a power of 180-220W and a frequency of 25kHz. Then add a 0.5% (w / w) amino silane coupling agent solution and stir at 35-40℃ for 20-30 minutes to complete the activation treatment. The amount of amino silane coupling agent used is 10-15 times the mass of sodium carboxymethyl cellulose.

[0020] After activation, filter and wash with deionized water 2-3 times to remove excess amino silane coupling agent. After activation, test the specific surface area of ​​sodium carboxymethyl cellulose to ensure that the specific surface area of ​​the cellulose derivative is greater than or equal to 150 m² / g.

[0021] Optionally, in step 2, the ultrasonic dispersion parameters are: power 200~300W, frequency 20~25kHz, dispersion time 20~30min; nitrogen bubbling flow rate 5~10mL / min, bubbling time 15~20min.

[0022] Optionally, in step 3, after adding the benzotriazole ethanol solution, the stirring speed is 300~500 r / min and the stirring time is 15~20 min; after adding the mixture, continue stirring for 10~15 min; after adding polyethylene glycol-b-polycaprolactone, increase the speed to 600~800 r / min and stir for 25~30 min.

[0023] The present invention also provides an application of the high-salt corrosion-inhibiting nano-permeable agent as described herein in oil and gas extraction.

[0024] This invention discloses a high-salt-resistant corrosion-inhibiting nano-permeable agent, its preparation method, and its application. By weight percentage, it comprises: 8-12% polyethylene glycol-β-polycaprolactone, 5-10% sodium gluconate, 5-10% nano-sized cellulose derivative, 0.3% oilfield-grade benzotriazole, and 0.6% industrial-grade sodium pyrophosphate, with the balance being a dispersion medium. The sum of the weight percentages of all components is 100%. The cellulose derivative is a cellulose derivative activated by a 0.5% silane coupling agent. This activates the three-dimensional porous network constructed by sodium carboxymethyl cellulose, improving the system's dispersion stability and water retention / permeability. Polyethylene glycol-β-polycaprolactone, with its amphiphilic structure, reduces the oil-water interfacial tension, accelerating permeation. Sodium gluconate and sodium pyrophosphate synergistically chelate high-salt ions, enhancing salt resistance. Furthermore, benzotriazole forms a dense protective film on the metal surface, which, combined with the anti-scaling and corrosion-inhibiting effects of sodium pyrophosphate, achieves highly efficient corrosion inhibition. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 This is a flowchart of a method for preparing a high-salt-resistant corrosion-inhibiting nano-permeable agent, which is optional according to an embodiment of the present invention. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] This application provides a high-salt corrosion-inhibiting nano-permeable agent, comprising, by weight percentage: 8-12% polyethylene glycol-b-polycaprolactone, 5-10% sodium gluconate, 5-10% nano-sized cellulose derivative, 0.3% oilfield-grade benzotriazole, 0.6% industrial-grade sodium pyrophosphate, with the balance being a dispersion medium, and the sum of the weight percentages of each component being 100%; the cellulose derivative is a cellulose derivative activated by 0.5% by mass of silane coupling agent.

[0029] Specifically, polyethylene glycol-b-polycaprolactone, as an amphiphilic block copolymer, combines hydrophilic polyethylene glycol segments with hydrophobic polycaprolactone segments; sodium gluconate is a water-soluble chelating agent with strong metal ion complexing ability; after activation treatment with 0.5% silane coupling agent by mass fraction, active functional groups are introduced on the surface of the cellulose derivative, significantly improving its dispersibility and interfacial interaction ability; oilfield-grade benzotriazole is a classic metal corrosion inhibitor with excellent adsorption performance and can form a protective film on the metal surface; industrial-grade sodium pyrophosphate is a water-soluble inorganic compound containing multidentate ligand groups, possessing both strong metal ion complexing ability and system dispersion stabilization effect.

[0030] Polyethylene glycol-β-polycaprolactone (PEG-β-polycaprolactone) reduces interfacial tension through its amphiphilic structure, facilitating rapid penetration of the adsorbent into the target medium and creating pathways for subsequent functionalization. Sodium gluconate chelates calcium and magnesium ions in high-salt environments, preventing precipitation reactions with other components and optimizing system dispersibility to enhance salt tolerance. Activated cellulose derivatives form stable interfacial bonds with other components through surface-active groups, constructing a three-dimensional network structure that strengthens the system's salt resistance and locks in active components to delay their loss. In the corrosion inhibition system, oilfield-grade benzotriazole chemically adsorbs onto the tubing metal surface to build a dense organic protective film, directly blocking the contact channels between chloride ions and the metal matrix. Industrial-grade sodium pyrophosphate, on the one hand, complexes calcium and magnesium ions to prevent them from forming insoluble scale (scale damages metal surface integrity and exacerbates localized chloride corrosion), reducing the exposure of active sites on the metal surface and lowering the probability of chloride adsorption corrosion. On the other hand, it complexes with metal ions to inhibit the initiation of corrosion reactions, while simultaneously regulating the system's pH to enhance the stability of the protective film, synergistically resisting chloride-dominated pitting and crevice corrosion. Through comprehensive synergy of absorption promotion, salt resistance optimization, and corrosion inhibition protection, each component achieves long-term protection against oil pipe corrosion and stable absorption function under high salt conditions.

[0031] In one possible implementation, the silane coupling agent is an amino-based silane coupling agent.

[0032] Specifically, the silane coupling agent in this application is an amino-based silane coupling agent, whose molecular structure possesses both amino and siloxane functional groups. The amino group is a strongly polar group and rich in active hydrogen atoms, while the siloxane group can undergo hydrolysis and condensation reactions in the presence of moisture. During the activation of cellulose derivatives, the amino-based silane coupling agent chemically bonds with the hydroxyl groups on the surface of the cellulose derivative through the siloxane group, achieving a strong grafting at the molecular level. Simultaneously, the amino groups in its molecule are exposed on the surface of the cellulose derivative, transforming the modified cellulose derivative from an inert surface into a functionalized material rich in active sites, laying the structural foundation for its interaction with other components in the system.

[0033] The amino groups on the surface of amino-based silane coupling agents can form hydrogen bonds with the ether bonds of polyethylene glycol-β-polycaprolactone and the carboxyl groups of sodium gluconate, and generate intermolecular forces with the heterocyclic structure of benzotriazole. This significantly improves the compatibility of cellulose derivatives with various functional components, avoids system stratification or precipitation, and enhances overall stability. Secondly, it optimizes the synergistic corrosion inhibition effect. The strong adsorption properties of amino groups can assist the directional adsorption of benzotriazole on metal surfaces, and at the same time, it forms a synergistic complexation with sodium pyrophosphate, further densifying the protective film on the metal surface and improving the corrosion resistance to chloride. Thirdly, it enhances the long-term salt resistance. The three-dimensional network structure of the cellulose derivative grafted with amino-silane coupling agents is more stable, which can effectively lock in the active components of permeation and reduce the loss in high-salt environments. At the same time, it inhibits the formation of scale and ensures that the permeation, salt resistance and corrosion inhibition performance are stable for a long time. Fourthly, it has strong compatibility. The hydrolysis and condensation reaction conditions of amino-silane coupling agents are mild and have good compatibility with the modification process of cellulose derivatives. Moreover, the modified cellulose derivatives still maintain good dispersibility and do not affect the overall permeation performance of the system.

[0034] The amino-based silane coupling agent of this application is selected from any one of 3-aminopropyltriethoxysilane (KH-550), 3-aminopropyltrimethoxysilane (KH-540) and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), and the purity of each is ≥98%.

[0035] In one possible implementation, the cellulose derivative is sodium carboxymethyl cellulose.

[0036] Specifically, the cellulose derivative in this application is sodium carboxymethyl cellulose, with a particle size of 10-100 nm, a degree of substitution of 0.6-1.2, a pH of 6.5-8.5 in a 1% aqueous solution, and a molecular weight of 10,000-200,000. Sodium carboxymethyl cellulose, as a water-soluble anionic polymer modified from natural cellulose through carboxylation, retains the rigid framework of cellulose in its molecular structure while introducing a large number of carboxymethyl hydrophilic groups. Sodium carboxymethyl cellulose combines the high specific surface area and excellent mechanical properties of nanoscale materials with the dispersion stability of water-soluble polymers. In permeabilizer systems, it can form multi-component interactions with other components through the carboxyl and hydroxyl groups on its molecular chain, and the anionic nature of the carboxymethyl group endows it with good metal ion complexing ability and salt environment adaptability.

[0037] Sodium carboxymethyl cellulose's water solubility and anionic properties allow it to dissolve rapidly in dispersion media and form a uniform dispersion system. Through electrostatic repulsion, it prevents the aggregation of itself and other components, avoiding system stratification or precipitation and improving the overall storage and use stability of the permeabilizer. Furthermore, the carboxyl groups of sodium carboxymethyl cellulose can form stable complexes with calcium and magnesium ions in high-salt environments, reducing scale formation and the risk of chloride ion corrosion. It also forms chelate synergistic effects with sodium gluconate and sodium pyrophosphate, enhancing the system's salt resistance. Moreover, the rigid molecular chains of sodium carboxymethyl cellulose can construct a flexible three-dimensional network structure, locking in permeabilizing active components such as polyethylene glycol-β-polycaprolactone, delaying their loss in high-salt environments. Simultaneously, it assists in the uniform adsorption of benzotriazole on metal surfaces, forming a dense corrosion-inhibiting protective film, achieving a long-term synergistic effect of permeabilization, salt resistance, and corrosion inhibition.

[0038] Sodium carboxymethyl cellulose is widely available, has a mature preparation process, and is highly compatible with the activation and modification process of amino silane coupling agents. After modification, it can still maintain good water solubility and dispersibility.

[0039] In one possible implementation, the dispersion medium is deionized water or simulated reservoir brine with a total salinity ≤200,000 mg / L.

[0040] Specifically, the dispersion medium is either deionized water or simulated reservoir brine with a total salinity ≤200,000 mg / L. Deionized water reduces interference from impurity ions, while simulated reservoir brine replicates the real high-salt environment by compounding common reservoir ions. Both media have good compatibility with the functional components. Deionized water ensures the system stability in laboratory research and low-salt conditions, while simulated reservoir brine, matching the salt tolerance threshold of the percolator, fits the actual application scenario in oilfields. The two media provide a clean environment and ion synergy conditions for the synergistic effect of the components, respectively. This avoids precipitation reactions caused by harmful ions and allows the ions in the simulated reservoir brine to form complexes with sodium gluconate and sodium pyrophosphate, supporting the percolation-promoting effect of polyethylene glycol-b-polycaprolactone and the corrosion-inhibiting film-forming effect of benzotriazole. At the same time, it broadens the application range of the percolator and ensures stable salt resistance, percolation, and corrosion inhibition performance under different salinity conditions.

[0041] This invention also provides a method for preparing a high-salt-resistant corrosion-inhibiting nano-permeabilizer, which is applied to the high-salt-resistant corrosion-inhibiting nano-permeabilizer described in this invention, comprising the following steps:

[0042] Step 1, Raw material pretreatment: Prepare benzotriazole ethanol solution and sodium pyrophosphate aqueous solution respectively. Activate the cellulose derivative with silane coupling agent. Mix the sodium pyrophosphate aqueous solution with sodium gluconate to obtain a mixed solution.

[0043] Step 2: Constructing a porous suspension: Add the activated cellulose derivative to the dispersion medium, disperse it by ultrasound, and then bubble it with a small amount of nitrogen gas to form a cellulose derivative suspension with a uniform porous structure.

[0044] Step 3, Component Mixing: Under stirring, add benzotriazole ethanol solution, sodium pyrophosphate-sodium gluconate mixture, and polyethylene glycol-b-polycaprolactone to the suspension obtained in Step 2 in sequence, and stir until the mixture is homogeneous;

[0045] Step 4, standing and testing: Let the mixture obtained in step 3 stand for 10 minutes, take a sample and test the pH value to be 6.0~8.0 and the nanoparticle dispersion size ≤30nm, then a qualified high salt corrosion inhibitor nano-permeable agent is obtained.

[0046] Specifically, in step 1, oilfield-grade benzotriazole is dissolved in ethanol to prepare a homogeneous benzotriazole ethanol solution. During this process, it is crucial to ensure complete dissolution of the benzotriazole and avoid residual solid particles. Industrial-grade sodium pyrophosphate is dissolved in water to prepare a sodium pyrophosphate aqueous solution. Sodium gluconate is then added and stirred until completely dispersed, forming a sodium pyrophosphate-sodium gluconate mixture. This process requires ensuring thorough integration of the two water-soluble components. Cellulose derivatives are then mixed and reacted with 0.5% (w / w) of an amino-based silane coupling agent under suitable conditions, allowing the silane coupling agent to graft onto the surface of the cellulose derivative. After activation, the solution is ready for use. Dissolution or activation eliminates the limitations imposed by the raw material form on subsequent mixing, preparing the solution for efficient integration of the components.

[0047] Step 2: Using deionized water or simulated reservoir brine with a total salinity ≤200,000 mg / L as the dispersion medium, add the activated cellulose derivative. Then, start the ultrasonic equipment to ultrasonically disperse the mixture, ensuring uniform dispersion and breaking up any potential agglomerates. After ultrasonication, perform a bubbling operation: connect a nitrogen cylinder to a gas pipe with a porous aerator head via a pressure reducing valve and flow meter. Fix the aerator head 3-5 cm below the liquid surface at the bottom of the container. Open the nitrogen cylinder valve and adjust the pressure reducing valve and flow meter to control the nitrogen flow rate at 5-10 mL / min, causing the aerator head to generate microbubbles with a diameter of 0.5-1 mm. During bubbling, maintain a low stirring speed of 50-100 rpm to prevent bubble aggregation. After continuous bubbling, turn off the nitrogen supply. Through the generation, slow rise, and escape of microbubbles, a uniform porous structure is formed in the suspension, ultimately yielding a stable porous cellulose derivative suspension.

[0048] Step 3: First, slowly add the benzotriazole ethanol solution prepared in Step 1 to the porous suspension prepared in Step 2, and stir for 1-2 minutes to initially disperse it; then add the sodium pyrophosphate-sodium gluconate mixture, and continue stirring until the system is homogeneous; finally, add polyethylene glycol-b-polycaprolactone, and continue stirring until the block copolymer is completely dissolved and integrated into the system. The system temperature should be controlled at 25-30℃ when adding polyethylene glycol-b-polycaprolactone.

[0049] Step 4: Place the container containing the product from Step 3 on a shockproof experimental platform and let it stand for 10 minutes. This allows the tiny air bubbles trapped during mixing to slowly rise and escape, while also allowing extremely fine impurity particles to settle to the bottom of the container. After standing, use a sterile glass sampler with a volume of 5-10 mL. Before sampling, rinse the sampler three times with deionized water and dry it. Slowly insert the sampler needle into the middle of the system (between the liquid surface and the bottom of the container) from the container opening along the inner wall. Slowly extract 2-3 mL of sample, avoiding the introduction of bottom sediment or surface air bubbles during sampling. Then, perform the detection. During the detection process, first rinse the pH meter probe with deionized water, blot the surface moisture with filter paper, and then insert it into the sample. After the reading stabilizes (usually 30 seconds to 1 minute), record the pH value. Simultaneously, inject 1 mL of sample into the special cuvette of the particle size analyzer, ensuring that the sample is free of air bubbles, and then place it into the instrument. Select the nanoparticle detection mode for measurement. If the test results show that the pH value is between 6.0 and 8.0 and the dispersed particle size of the nanoparticles is ≤30nm, the system can be directly transferred to a sealed storage tank to obtain a qualified product. If the pH value is too low, a small amount of 0.1mol / L sodium hydroxide solution can be added to adjust it. If it is too high, a small amount of 0.1mol / L hydrochloric acid solution can be added. If the particle size exceeds the standard, return to step 2 to perform ultrasonic dispersion again, adjust the parameters, and complete the subsequent steps again until the indicators meet the standards to ensure that the final product meets the usage requirements.

[0050] In one possible implementation, the preparation process of the benzotriazole ethanol solution in step 1 is as follows: take the formula amount of oilfield grade benzotriazole, add 3 to 5 times its mass of industrial ethanol, and stir at 25 to 30°C for 10 to 15 minutes until completely dissolved.

[0051] The preparation process of sodium pyrophosphate aqueous solution is as follows: take the formula amount of industrial grade sodium pyrophosphate, add 8 to 10 times its mass of 30℃ warm water, and stir for 5 to 8 minutes until fully dissolved.

[0052] Specifically, the preparation of benzotriazole ethanol solution is as follows: Weigh out oilfield-grade benzotriazole with a purity ≥98% and slowly pour it into an Erlenmeyer flask. Measure 3-5 times its mass of industrial ethanol with a purity ≥95% and a water content ≤5%, and slowly pour it in along a glass rod to avoid splashing. Place a clean stir bar in the flask and heat it to 25-30°C in a constant temperature water bath. After confirming the solution temperature matches the water bath temperature with a thermometer with an accuracy of 0.1°C, stir at 250-300 rpm for 10-15 minutes, observing every 2 minutes, until the solution is homogeneous, transparent, and free of solid residue, indicating complete dissolution. If not completely dissolved, extend stirring for 2-3 minutes or check the ethanol purity and water temperature. After dissolution, turn off the equipment and seal the flask with a stopper to prevent ethanol evaporation.

[0053] Preparation of sodium pyrophosphate aqueous solution: Place industrial-grade sodium pyrophosphate (purity ≥96%) into a beaker. After preheating deionized water to a stable temperature of 30℃±1℃, add 8-10 times the mass of the sodium pyrophosphate to the beaker. Confirm the solution temperature using a thermometer (28-32℃). Insert the stirrer into the middle of the solution (1-2 cm from the bottom of the beaker) and stir at 150-200 rpm for 5-8 minutes, observing every minute. The solution is considered fully dissolved when it is colorless, transparent, and free of precipitate or clumps. For localized clumps, gently rotate the beaker to aid dispersion. After dissolution, turn off the stirrer and place the solution in a 30℃ water bath for later use to prevent precipitation due to cooling.

[0054] In one possible implementation, in step 1, the cellulose derivative is sodium carboxymethyl cellulose, the silane coupling agent is an amino-based silane coupling agent, and the process of activating the cellulose derivative with the silane coupling agent is as follows:

[0055] Take the prescribed amount of cellulose derivative, add 5-8 times its mass of deionized water, and ultrasonically create pores for 15-20 minutes at a power of 180-220W and a frequency of 25kHz. Then add a 0.5% (w / w) silane coupling agent solution and stir at 35-40℃ for 20-30 minutes to complete the activation treatment. The amount of silane coupling agent solution used is 10-15 times the mass of the cellulose derivative.

[0056] After activation, filter and wash 2-3 times with deionized water to remove excess silane coupling agent. After activation, measure the specific surface area of ​​the cellulose derivative to ensure it is greater than or equal to 150 m². 2 / g.

[0057] Specifically, weigh the sodium carboxymethyl cellulose powder according to the formulation requirements for standby. At the same time, measure deionized water at or above the first grade with a volume 5 to 8 times its mass, and inject it into a three-neck flask equipped with a mechanical stirring paddle and a thermometer interface. Then, carry out ultrasonic pore-forming treatment. Start the stirrer and slowly add the sodium carboxymethyl cellulose powder along the stirring direction into the water at a rate of 200 to 300 r / min to avoid accumulation. After the powder is added, increase the stirring rate to 300 to 400 r / min and pre-stir for 5 min to form a homogeneous suspension. Subsequently, fix the flask on the ultrasonic generator, make the ultrasonic probe penetrate into the suspension, set the power to 180 to 220 W and the frequency to 25 kHz, and carry out ultrasonic pore-forming for 15 to 20 min. During the process, monitor the temperature in real time. If it exceeds 40 °C, pause for 1 to 2 min to cool down. Observe the state of the suspension every 5 min to ensure there is no obvious precipitation. Keep stirring after ultrasonic treatment for standby. Finally, carry out the activation reaction of the amino-silane coupling agent: Place the three-neck flask containing the ultrasonic-treated dispersion liquid in a constant-temperature water bath, heat it up to 35 to 40 °C and stabilize for 10 min. Maintain the stirring rate of 300 to 400 r / min, and slowly drip the prepared coupling agent solution into the dispersion liquid through a constant-pressure dropping funnel. After the dripping is completed, continue to stir at a constant temperature at this temperature for 20 to 30 min to ensure that the reaction proceeds fully to complete the activation. After the reaction is completed, turn off the relevant equipment and let it stand for 5 min.

[0058] After the above activation reaction and standing steps are completed, the activated product needs to be immediately separated, washed and quality-tested to ensure that it meets the usage requirements for the preparation of subsequent imbibition agents. When separating and washing the product, first transfer the activated reaction system to a Buchner funnel, and achieve solid-liquid separation through vacuum filtration. After collecting the filter cake, redisperse it with an appropriate amount of deionized water, stir evenly and then carry out vacuum filtration again. Repeat the washing 2 to 3 times to thoroughly remove the unreacted coupling agent and reaction by-products remaining on the surface of the filter cake. After each washing operation is completed, a small amount of the washing filtrate can be sampled for detection until no coupling agent residue is detected in the filtrate, which is regarded as qualified washing. The core index of quality testing is the specific surface area. The specific operation is as follows: Put the qualified washed filter cake into a vacuum drying oven and dry it at 55 to 65 °C and -0.1 to -0.08 MPa until the mass is constant. Take the dried sample and place it in a special sample tube. First, degas it at a temperature of 90 to 110 °C for 1.5 to 2.5 h to remove the impurities and moisture adsorbed on the surface of the sample, and then use the BET method (liquid nitrogen adsorption-desorption method) to measure its specific surface area. To ensure the accuracy of the data, the detection process needs to be repeated 3 to 5 times and the average value is taken. If the final test result shows that the specific surface area of the sample ≥ 150 m² / g, it means that the activated product meets the quality standard and can be used for the preparation of subsequent high-salt-resistant corrosion-inhibiting nano-imbibition agents. If the specific surface area does not meet this requirement, it is necessary to adjust the key conditions such as ultrasonic power, ultrasonic time or coupling agent dosage according to the actual experimental situation, and reactivate the cellulose derivative.

[0059] In one possible implementation, in step 2, the ultrasonic dispersion parameters are: power 200~300W, frequency 20~25kHz, dispersion time 20~30min; nitrogen bubbling flow rate is 5~10mL / min, bubbling time is 15~20min.

[0060] Specifically, the ultrasonic dispersion parameters are set as follows: power 200~300W, frequency 20~25kHz, and dispersion time 20~30min. This parameter range allows for the full fragmentation and uniform dispersion of material particles within the system through moderate ultrasonic energy impact, preventing particle agglomeration, while avoiding damage to the material structure due to excessive energy. Nitrogen bubbling is carried out continuously at a flow rate of 5~10mL / min for 15~20min. This not only enhances the material dispersion effect through the stirring action of nitrogen, but also isolates the material from air through the nitrogen atmosphere, preventing oxidation and deterioration during the dispersion process. Furthermore, it can promptly remove trace bubbles and volatile impurities generated by ultrasonic dispersion, ultimately ensuring a uniform and stable dispersion system, laying the foundation for the smooth progress of subsequent reactions and the improvement of product performance.

[0061] In one possible implementation, in step 3, the stirring speed after adding the benzotriazole ethanol solution is 300~500 r / min, and the stirring time is 15~20 min; after adding the mixture, stirring continues for 10 min; after adding polyethylene glycol-b-polycaprolactone, the stirring speed is increased to 600~800 r / min, and stirring is carried out for 25~30 min.

[0062] Specifically, after adding the benzotriazole ethanol solution, stirring at 300-500 rpm for 15-20 minutes ensures sufficient contact and mixing between the solution and the system, allowing the benzotriazole to disperse uniformly and initially exert its pre-binding effect as a corrosion inhibitor, while avoiding excessive bubble formation due to excessive speed. Continuing to stir for 10 minutes after adding the mixture allows the newly added material to quickly integrate with the existing system, maintaining system stability. After adding polyethylene glycol-β-polycaprolactone, the speed is increased to 600-800 rpm and stirred for 25-30 minutes. The higher speed breaks up any potential local aggregation of polyethylene glycol-β-polycaprolactone, promoting its full grafting onto the surface of the cellulose derivative. Extending the stirring time ensures a more thorough grafting reaction. This gradient setting of stirring parameters achieves orderly dispersion and reaction of the components while ensuring the final product possesses both good corrosion inhibition performance and dispersion stability, providing a guarantee for the application of the penetrant in high-salt environments. When adding polyethylene glycol-b-polycaprolactone, the system temperature needs to be controlled at 25~30℃.

[0063] This invention also provides the application of a high-salt-resistant corrosion-inhibiting nano-permeable agent in oil and gas extraction.

[0064] Specifically, after the high-salt corrosion-inhibiting nano-permeabilizer of this invention is injected into the oil and gas reservoir through a liquid injection process, on the one hand, the nano-sized active components can efficiently penetrate into the reservoir pores and micro-fractures through permeation, reducing the oil-water interfacial tension to promote crude oil stripping and flow, and improving oil and gas recovery rate; on the other hand, its corrosion-inhibiting components can form a dense protective film on the surface of metal equipment such as sucker rods and tubing, inhibiting electrochemical corrosion in high-salt environments, reducing equipment wear and maintenance costs. At the same time, the permeabilizer itself has excellent salt resistance and stability, and is not easily deactivated in high-salt formation water. It can play a dual role of permeation oil recovery and corrosion protection for a long time, providing a guarantee for the efficiency and safety of oil and gas extraction.

[0065] The present application is further illustrated by the following embodiments.

[0066] 1. Raw materials

[0067] Polyethylene glycol-β-polycaprolactone: 50g, molecular weight 5000~10000, PEG / PCL block ratio 1:1; wherein, PEG is polyethylene glycol and PCL is polycaprolactone;

[0068] Sodium gluconate: 40g, industrial grade, purity ≥98%;

[0069] Sodium carboxymethyl cellulose: 40g, degree of substitution 0.8~1.0;

[0070] Oilfield grade benzotriazole: 1.5g, purity ≥95%;

[0071] Industrial grade sodium pyrophosphate: 3g, purity ≥96%;

[0072] Simulated reservoir brine: 365.5g, total salinity 200,000 mg / L (containing Cl) - 100000mg / L, Ca 2+ 8000mg / L, Mg 2+ 5000mg / L)

[0073] Auxiliary materials: 6g of industrial ethanol, 480g of 0.5% aminosilane coupling agent solution, the aminosilane coupling agent is KH-550, purity ≥98%.

[0074] 2. Experimental equipment

[0075] Ultrasonic cell disruptor (0~300W, 20~25kHz), electric stirrer (0~1000r / min).

[0076] Vacuum filtration device, vacuum drying oven (0~200℃), nitrogen cylinder (with flow meter);

[0077] Electronic balance (accuracy 0.001g), constant temperature water bath (temperature control ±0.5℃), zeta potential meter, rotational viscometer (0~1000mPa·s), surface tension meter, self-priming percolator.

[0078] 3. Example - Preparation Process

[0079] Step 1: Raw material pretreatment

[0080] 1.1. Preparation of benzotriazole solution: Dissolve 1.5g of benzotriazole in 6g of industrial ethanol, stir at 28℃ for 12min until completely transparent, and set aside.

[0081] 1.2. Preparation of chelation mixture: Dissolve 3g sodium pyrophosphate in 27g warm water at 30℃, stir for 5min, then add 40g sodium gluconate, and continue stirring for 8min until dissolved, and set aside.

[0082] 1.3. Activation of sodium carboxymethyl cellulose: 40g of sodium carboxymethyl cellulose was added to 240g of deionized water and pre-stirred for 10min to form a suspension; ultrasonication was performed at 200W and 25kHz for 18min; the temperature during ultrasonication did not exceed 40℃. Under a constant temperature water bath of 38℃, 480g of 0.5% aminosilane coupling agent solution was added dropwise and stirred for 25min; after filtration, the solution was washed three times with deionized water and vacuum dried at 60℃ to constant weight. The specific surface area was measured to be ≥150m². 2 / g.

[0083] Step 2: Construction of porous suspension

[0084] Pour 365.5g of simulated reservoir brine into a container and slowly add activated sodium carboxymethyl cellulose; start the ultrasonic cell disruptor (250W, 22kHz) and ultrasonically disperse for 25min; then place the nitrogen aerator 3cm below the liquid surface and bubble nitrogen at a flow rate of 8mL / min for 18min to form a uniform porous suspension.

[0085] Step 3: Component gradient mixing

[0086] 3.1. Slowly add benzotriazole solution while stirring at 400 r / min, and maintain stirring speed for 18 min.

[0087] 3.2. Add the chelation mixture at the same rotation speed and stir for 10 minutes.

[0088] 3.3. Add 50g of polyethylene glycol-b-polycaprolactone, increase the speed to 700r / min, and stir at 25~30℃ for 28min until completely dissolved.

[0089] Step 4: Finished Product Quality Control and Judgment

[0090] Transfer the mixture to a sealed container and let it stand for 10 minutes to remove trapped air bubbles; take a sample from the middle of the container for testing: pH value 7.2; nanoparticle dispersion size 18nm. If both indicators meet the standards, it is a qualified percolator.

[0091] 4. Testing parameters (conducted at 60℃)

[0092] 4.1. High salt tolerance: including basic system stability and osmotic stability;

[0093] 4.1.1. System stability: The initial dispersed particle size, 72h particle size change rate, zeta potential, viscosity change, and stratification after standing were measured. The requirements are: particle size change rate ≤20%, absolute value of zeta potential ≥30mV, viscosity change rate ≤15%, and no stratification.

[0094] 4.1.2. Stable Irradiation Function: Initial and 72-hour surface tension, interfacial tension, and self-absorption height were measured. Surface tension was required to be ≤35 mN / m, interfacial tension ≤1.5 mN / m, and the rate of change in self-absorption height ≤10%. Testing methods: Basic stability: A 50 mL sample was placed at 60℃ and allowed to stand. Particle size, potential, and viscosity were measured at 0 h and 72 h. Functional stability: Surface tension was measured using the ring method, interfacial tension using the pendant drop method, and self-absorption height (cumulative value over 72 h) was measured using a self-absorption analyzer (natural core, φ25 mm × 50 mm).

[0095] 4.2. Permeation efficiency: Displacement experiments were conducted using natural rock cores (specifications φ25mm×50mm, porosity 18%~22%, permeability 100~200mD). The "increase in core permeation recovery rate" was used as the indicator, and the requirement was ≥15%.

[0096] 4.3. Corrosion Inhibition Performance: 1. Material Selection: 20CrMo steel was used. 2. Testing Method: The loss-in-weight method was used. The specific steps were as follows: Take a 20CrMo steel sample (20mm×10mm×2mm), polish it sequentially with 400#, 800#, and 1200# sandpaper, degrease it with anhydrous ethanol for 10 minutes, rinse it with deionized water, dry it, and weigh it accurately (recorded as m1, with an accuracy of 0.001g); immerse the sample completely in simulated reservoir brine containing 5% of the percolating agent from the example, and corrode it at a constant temperature of 60℃ and 150r / min for 72 hours; remove the sample and remove it with a rust remover (5% lemon juice). Soak in acid + 0.5% thiourea for 3-5 minutes to remove corrosion products (visually judged by the absence of rust spots), then degrease with anhydrous ethanol, rinse with deionized water, blow dry and weigh (recorded as m2); corrosion rate and corrosion inhibition rate are calculated as follows: corrosion rate v = (m1-m2) × 87600 / (S × t × ρ) (S is the surface area of ​​the test piece, t is the corrosion time, ρ is the steel density 7.85 g / cm³), corrosion inhibition rate η = (v0-v1) / v0 × 100% (v0 is the corrosion rate of blank brine, v1 is the corrosion rate of the sample).

[0097] 3. Standard requirements: corrosion rate ≤ 0.1 mm / a, corrosion inhibition rate ≥ 85%.

[0098] 5. Test Results

[0099] The results of each performance test index are shown in Table 1:

[0100] Table 1 Test Results

[0101] Detection index Unit Detection value Standard requirement Initial dispersed particle size nm 18 ≤ 30 nm Dispersed particle size after 72 h nm 21 - Particle size change rate % 16.7 ≤20% Zeta potential after 72 h mV -35.2 Absolute value ≥ 30 mV Initial viscosity (60°C) mPa·s 85 - Viscosity after 72 h (60°C) mPa·s 78 - Viscosity change rate % 8.2 ≤15% Oil-water interfacial tension mN / m 0.9 (RSD = 2.1%) ≤ 1.5 mN / m, RSD ≤ 3% Core recovery rate improvement range % 22.3 ≥15% Corrosion rate of 20CrMo steel (sucker rod steel) mm / a 0.072 ≤ 0.1 mm / a Corrosion inhibition rate % 88.7 ≥85% 72 h standing stratification - No stratification, uniform and stable No stratification

[0102] 6. Blank test verification (corrosion inhibition performance)

[0103] To eliminate the interference of the inherent corrosion resistance of 20CrMo steel on the test results, a blank control group was set up for comparison with the experimental group to verify the corrosion inhibition and synergistic effect of the penetrant. The specific design and results are as follows:

[0104] 6.1. Experimental design: Both groups used simulated reservoir brine (total salinity 200,000 mg / L) as the corrosive medium and underwent constant temperature oscillation corrosion at 60℃ and 150 r / min for 72 h; the experimental group contained 5% of the permeate from the example, while the blank group contained no permeate component, and all other conditions were completely identical.

[0105] 6.2. Test materials and pretreatment: Both groups used 20CrMo steel test pieces (20mm×10mm×2mm), which were polished with 400# / 800# / 1200# sandpaper, degreased with anhydrous ethanol for 10 min, rinsed with deionized water, dried and weighed (the experimental group was recorded as m1 and the blank group as m0).

[0106] 6.3. Data Results: After corrosion and the same post-treatment, the corrosion rate of the blank group was v0=0.637mm / a, and the corrosion rate of the experimental group was v1=0.072mm / a. The corrosion inhibition rate was calculated to be 88.7% using the formula η=(v0-v1) / v0×100%, which proves the corrosion protection and strengthening effect of the penetrant on 20CrMo steel.

[0107] 7. Conclusion

[0108] Based on the test results, the high-salt resistant corrosion-inhibiting nano-permeabilizer prepared using the proposed method fully meets the performance requirements of high-salt reservoir extraction, and the preparation process has industrialization potential. Regarding high-salt stability, the permeabilizer initially disperses at 18 nm, increasing to 21 nm after 72 hours, with a particle size change rate of only 16.7%. Its zeta potential reaches -35.2 mV, and its initial viscosity is 85 mPa·s, increasing to 78 mPa·s after 72 hours, with a viscosity change rate of 8.2%. It exhibits no stratification and remains homogeneous and stable after standing for 72 hours in a high-salt environment at 60℃, making it suitable for harsh reservoir environments. In terms of permeation and oil displacement performance, its oil-water interfacial tension is as low as 0.9 mN / m (relative standard deviation 2.1%), and its core recovery rate increases by 22.3%, significantly exceeding the target, effectively reducing oil-water interfacial resistance and improving crude oil extraction efficiency. It exhibits outstanding corrosion inhibition and protection performance, with a corrosion rate of only 0.072 mm / a for 20CrMo steel commonly used in sucker rods, and a corrosion inhibition rate of 88.7%, effectively reducing corrosion losses of downhole equipment. Therefore, this penetrant and its preparation method provide a reliable guarantee for large-scale production and field application.

[0109] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-salt-resistant corrosion-inhibiting nano-permeable agent, characterized in that, By weight percentage, it comprises: 8-12% polyethylene glycol-β-polycaprolactone, 5-10% sodium gluconate, 5-10% nano-sized cellulose derivative, 0.3% benzotriazole, 0.6% industrial grade sodium pyrophosphate, with the balance being a dispersion medium, and the sum of the weight percentages of all components is 100%; the cellulose derivative is a cellulose derivative activated by 0.5% by mass of silane coupling agent; The purity of the benzotriazole is ≥95%. The cellulose derivative is sodium carboxymethyl cellulose, the silane coupling agent is an amino-based silane coupling agent, and the process of activating the cellulose derivative with the silane coupling agent is as follows: Take the prescribed amount of sodium carboxymethyl cellulose, add 5-8 times its mass of deionized water, and ultrasonically create pores for 15-20 minutes at a power of 180-220W and a frequency of 25kHz. Then add a 0.5% (w / w) amino silane coupling agent solution and stir at 35-40℃ for 20-30 minutes to complete the activation treatment. The amount of amino silane coupling agent used is 10-15 times the mass of sodium carboxymethyl cellulose. After activation, filter and wash 2-3 times with deionized water to remove excess aminosilane coupling agent. After activation, measure the specific surface area of ​​sodium carboxymethyl cellulose to ensure that the specific surface area of ​​the cellulose derivative is greater than or equal to 150 m². 2 / g.

2. The high-salt-resistant corrosion-inhibiting nano-permeable agent according to claim 1, characterized in that, The dispersion medium is deionized water or simulated reservoir brine with a total salinity ≤200,000 mg / L.

3. A method for preparing a high-salt-resistant corrosion-inhibiting nano-permeation agent, characterized in that, The application of the high-salt corrosion-inhibiting nano-permeable agent according to claim 1 or 2 includes the following steps: Step 1, Raw material pretreatment: Prepare benzotriazole ethanol solution and sodium pyrophosphate aqueous solution respectively. Activate the cellulose derivative with silane coupling agent. Mix the sodium pyrophosphate aqueous solution with sodium gluconate to obtain a mixed solution. Step 2: Constructing a porous suspension: Add the activated cellulose derivative to the dispersion medium, disperse it by ultrasound, and then bubble it with a small amount of nitrogen gas to form a cellulose derivative suspension with a uniform porous structure. Step 3, Component Mixing: Under stirring, add benzotriazole ethanol solution, sodium pyrophosphate-sodium gluconate mixture, and polyethylene glycol-b-polycaprolactone to the suspension obtained in Step 2 in sequence, and stir until the mixture is homogeneous; Step 4, standing and testing: Let the mixture obtained in step 3 stand for 10 minutes, take a sample and test the pH value to be 6.0~8.0 and the nanoparticle dispersion size ≤30nm, then a qualified high salt corrosion inhibitor nano-permeable agent is obtained.

4. The preparation method of the high-salt corrosion-inhibiting nano-permeation agent according to claim 3, characterized in that, In step 1, the preparation process of benzotriazole ethanol solution is as follows: take the formula amount of oilfield grade benzotriazole, add 3 to 5 times its mass of industrial ethanol, and stir at 25 to 30°C for 10 to 15 minutes until completely dissolved. The preparation process of sodium pyrophosphate aqueous solution is as follows: take the formula amount of industrial grade sodium pyrophosphate, add 8 to 10 times its mass of 30℃ warm water, and stir for 5 to 8 minutes until fully dissolved.

5. The preparation method of the high-salt corrosion-inhibiting nano-permeation agent according to claim 3, characterized in that, In step 1, the cellulose derivative is sodium carboxymethyl cellulose, the silane coupling agent is an amino-based silane coupling agent, and the process of activating the cellulose derivative with the silane coupling agent is as follows: Take the prescribed amount of sodium carboxymethyl cellulose, add 5-8 times its mass of deionized water, and ultrasonically create pores for 15-20 minutes at a power of 180-220W and a frequency of 25kHz. Then add a 0.5% (w / w) amino silane coupling agent solution and stir at 35-40℃ for 20-30 minutes to complete the activation treatment. The amount of amino silane coupling agent used is 10-15 times the mass of sodium carboxymethyl cellulose. After activation, filter and wash 2-3 times with deionized water to remove excess aminosilane coupling agent. After activation, measure the specific surface area of ​​sodium carboxymethyl cellulose to ensure that the specific surface area of ​​the cellulose derivative is greater than or equal to 150 m². 2 / g.

6. The preparation method of the high-salt corrosion-inhibiting nano-permeation agent according to claim 3, characterized in that, In step 2, the ultrasonic dispersion parameters are: power 200~300W, frequency 20~25kHz, dispersion time 20~30min; nitrogen bubbling flow rate is 5~10mL / min, bubbling time is 15~20min.

7. The preparation method of the high-salt corrosion-inhibiting nano-permeation agent according to claim 3, characterized in that, In step 3, after adding the benzotriazole ethanol solution, the stirring speed is 300~500 r / min and the stirring time is 15~20 min; after adding the mixture, continue stirring for 10~15 min; after adding polyethylene glycol-b-polycaprolactone, increase the speed to 600~800 r / min and stir for 25~30 min.

8. The application of a high-salt-resistant, corrosion-inhibiting nano-permeable agent as described in claim 1 or 2 in oil and gas extraction.

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