A method for preparing high-tungsten alloy oil casing

Abstract

This invention provides a method for preparing a high-tungsten alloy oil casing, belonging to the field of oil casing technology, comprising the following steps: cleaning, crushing, vacuuming and filling with argon gas, heating and melting, casting, annealing, cooling, and sandblasting the inner wall to obtain a pretreated high-tungsten alloy tube; mixing Zn(NO3)2·6H2O, pretreated Na2MoO4, methanol, and 2-methylimidazole, adding sodium hydroxide solution and water, stirring, centrifuging, immersing in Tris-DA solution, centrifuging, and vacuum drying to obtain loaded MoO4. 2‑ Zeolite microcapsules; epoxy-modified silicone resin and polyamide are mixed and magnetically stirred, and then loaded with MoO4 is added. 2‑ A mixture of zeolite microcapsules was prepared by slow stirring; a pretreated high-tungsten alloy tube was immersed in the mixture, wetted, preheated, and cooled to obtain a high-tungsten alloy oil casing. This invention provides resistance to CO2 / H2S corrosion while also exhibiting a certain degree of impact resistance.

Description

Technical Field

[0001] This invention relates to the field of tubing and casing technology, and specifically to a method for preparing a high-tungsten alloy tubing and casing. Background Technology

[0002] Oil casing is a crucial component of oil and gas extraction equipment, serving as wellbore support and access pathways during the extraction process. CO2 / H2S corrosion is the most common corrosive medium in oil and gas systems. While dry CO2 and H2S have no effect on steel materials, when CO2 and H2S gases dissolve in water or form weak acids in produced fluids containing water, they can cause corrosion damage to steel casing, leading to casing failure. This not only results in incalculable economic losses but also constantly threatens life and environmental safety.

[0003] To combat CO2 / H2S corrosion, high-alloy corrosion-resistant materials are the preferred choice. However, due to the characteristics of oil and gas fields being mostly characterized by low oil content and low permeability, using chromium-based or nickel-based corrosion-resistant materials for oil casing is not only costly but also lacks sufficient impact resistance. Chinese patent document CN110303066A discloses a high lateral impact energy oil casing steel and its preparation method. In this method, molten steel is continuously cast into slabs, which are then sequentially heated, rough-rolled, finish-rolled, and laminar-flow cooled to obtain the finished product. No heat treatment is used in this method. Although the lateral impact energy of the steel is improved through the corresponding rolling process, the CO2 / H2S corrosion resistance of the oil casing is not resolved. Rare earth elements are widely used in seawater corrosion-resistant and atmospheric corrosion-resistant steels, but research and application in steels for high-temperature, high-pressure CO2 / H2S corrosion in oil and gas fields are relatively limited.

[0004] Therefore, there is a need to provide a method for preparing high-tungsten alloy oil casing to solve the problems existing in the prior art. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing a high-tungsten alloy oil casing that is resistant to CO2 / H2S corrosion and has a certain degree of impact resistance.

[0006] To achieve the above objectives, the present invention provides a method for preparing a high-tungsten alloy oil casing, comprising the following steps:

[0007] S1. Tungsten, chromium, nickel, iron, chromium nitride and yttrium are cleaned, crushed, vacuumed and filled with argon, heated and melted, cast, annealed and cooled to obtain a high tungsten alloy tube, and its inner wall is sandblasted to obtain a pretreated high tungsten alloy tube.

[0008] S2. Mix Zn(NO3)2·6H2O, pretreated Na2MoO4, and methanol to obtain mixture A; mix 2-methylimidazole and methanol to obtain mixture B; mix mixture A and mixture B, add sodium hydroxide solution to adjust the pH, stir magnetically, centrifuge, collect the precipitate, wash, immerse in Tris-DA solution, centrifuge, collect the precipitate, wash, and vacuum dry to obtain supported MoO4. 2- Zeolite microcapsules;

[0009] S3. Mix epoxy-modified silicone resin and polyamide, stir magnetically, and add loaded MoO4. 2- Zeolite microcapsules are slowly stirred and sonicated to prepare a mixture; a pretreated high-tungsten alloy tube is immersed in the mixture, wetted, leveled, preheated, kept at a certain temperature, and cooled to obtain a high-tungsten alloy oil sleeve.

[0010] The matrix of this invention adopts a multi-component high-entropy alloy system, achieving high corrosion resistance and mechanical properties through the synergistic effect of multiple elements. Tungsten is the main element, and its high melting point and hardness significantly improve the alloy's high-temperature resistance and impact resistance. Chromium oxidizes on the surface to form a dense passivation film, blocking H2S corrosion. At the same time, it synergistically forms a composite oxide (Cr2O3-WO3) with tungsten, giving the passivation film a certain self-healing ability and further inhibiting the penetration of acidic media (H2CO3 generated by CO2 hydrolysis). The nitrogen element introduced by the chromium nitride pre-alloy fills the lattice interstices, enhancing the stability of the passivation film and inhibiting the anodic dissolution reaction in CO2 corrosion. In addition, yttrium can preferentially react with H2S to form Y2S3 particles (rather than brittle FeS), reducing the tendency of sulfide stress corrosion. Furthermore, yttrium can refine the grains in intermetallic compounds. Smaller grains can increase the grain boundary area, thereby improving the alloy's impact resistance and toughness.

[0011] This invention prepares MoO4-supported 2- Zeolite microcapsules enable the processing of MoO4 2- Selective release of the anti-corrosion component. 2-Methylimidazole, acting as a ligand, can react with Zn. 2+ Ion coordination forms metal complexes, resulting in a ZIF-8 zeolite structure. This allows Na₂MoO₄ to be distributed within or encapsulated in the pores of the ZIF-8 zeolite. Polydopamine is then applied to the outside of the zeolite, enabling a dual-response release mechanism based on pH and reactive oxygen species, precisely repairing corrosion sites. When CO₂ corrosion creates an acidic environment with a local pH < 4, the polydopamine shell degrades, releasing MoO₄. 2- The corrosion-resistant component, and the H2O2 generated by H2S corrosion triggers the oxidative cracking of polydopamine, accelerating the oxidation of MoO4. 2- Release of corrosion-resistant components. MoO4 2- It can inhibit the propagation of pitting corrosion and form a MoS2 protective layer in the H2S environment, reducing the susceptibility to sulfide stress corrosion cracking; in addition, MoO42- with Fe 2+ The formation of FeMoO4 precipitate can repair damaged areas of the coating, further improving corrosion resistance and durability.

[0012] This invention uses epoxy-modified silicone resin as the coating material for oil pipelines. It combines the high adhesion of epoxy resin with the high temperature resistance and corrosion resistance of silicone resin, effectively resisting corrosive media such as acids, salts, and sulfides encountered by oil pipelines in various environments. Furthermore, the high temperature resistance of the epoxy-modified silicone resin remains stable at high temperatures; it also prevents aging and cracking of the coating under prolonged exposure to sunlight. Simultaneously, the coating possesses excellent waterproof properties, effectively resisting moisture and water penetration, thereby preventing water-induced corrosion or expansion problems and ensuring the long-term durability of the pipeline.

[0013] Optionally, the high-tungsten alloy tube is made by ultrasonically cleaning tungsten, chromium, nickel, iron, chromium nitride, and yttrium, then crushing them, placing them in an electric arc furnace, and evacuating them to 10°C. -3 After Pa, argon gas is introduced, and the temperature is raised to 3500℃ for 30-120 minutes to melt. During this period, electromagnetic stirring is continuously carried out. Then, it is poured into a mold, annealed at 700℃ for 10 hours, and then air-cooled to obtain the final product.

[0014] This invention uses ultrasonic cleaning to remove impurities from the surface of the base material, while continuous electromagnetic stirring ensures that all components are mixed evenly.

[0015] Optionally, after obtaining the high-tungsten alloy tube in step S1, the inner wall of the high-tungsten alloy tube is sandblasted at 0.6 MPa, the inner wall is wiped with acetone, and dried with hot air at 60°C for 30 minutes to obtain a pretreated high-tungsten alloy tube.

[0016] This invention utilizes acetone to wipe the inner wall, removing oil and dust.

[0017] Optionally, the Tris-DA solution is prepared by dissolving Tris-HCl in deionized water, adjusting the pH to 8.5 with hydrochloric acid, and then adding dopamine hydrochloride and stirring until homogeneous.

[0018] Optionally, the pretreated Na2MoO4 is obtained by ball milling Na2MoO4 for 12 to 24 hours.

[0019] Optionally, mixture A is prepared by uniformly mixing Zn(NO3)2·6H2O, pretreated Na2MoO4, Ce(NO3)3·6H2O, Ga(NO3)3, and methanol, and then magnetically stirring for 10–20 min; mixture B is prepared by dissolving 2-methylimidazole in methanol and magnetically stirring for 10–20 min.

[0020] This invention prepares MoO4-supported2- Ce(NO3)3·6H2O and Ga(NO3)3 were also added during the zeolite microcapsule process. 3+ Ga 3+ With MoO4 2- Coexisting in ZIF-8 channels, Ga 3+ and Ce 3+ Under alkaline conditions, a hydroxide precipitate forms and is encapsulated within it. In a high H2S environment, Ga... 3+ and Ce 3+ It can react with H2S to form stable sulfides, further reducing free S. 2- Attacks on the substrate.

[0021] Optionally, in step S2, mixture A and mixture B are mixed thoroughly, and the pH is adjusted to 10.0 with a 0.1 mol / L sodium hydroxide solution. The mixture is then magnetically stirred at 500 rpm for 12 hours at 25°C. Deionized water is added, and the mixture is stirred for 5–10 minutes. The mixture is then centrifuged at 8000 rpm for 5–15 minutes, the supernatant is discarded, and the precipitate is collected. The precipitate is washed three times alternately with methanol and deionized water, then placed in Tris-DA solution and continuously exposed to ambient oxygen at room temperature for 24 hours. Subsequently, the mixture is centrifuged at 2000 rpm for 5–10 minutes, the precipitate is collected, washed with deionized water, and then vacuum dried at 40–60°C for 24 hours to obtain supported MoO4. 2- Zeolite microcapsules.

[0022] Optionally, in step S3, epoxy-modified silicone resin and polyamide are mixed, magnetically stirred, loaded MoO42-zeolite microcapsules are added, stirred slowly, xylene and defoamer are added dropwise, and the stirring time is 2-5 minutes. The mixture is then sonicated to obtain a mixture.

[0023] Optionally, in step S3, the magnetic stirring speed is 300 rpm and the time is 5-10 min, the slow stirring speed is 100 rpm and the stirring time is 2-5 min, the ultrasonic temperature is 20℃ and the time is 20-30 min, and the ultrasonic process is paused for 10 seconds every 5 min.

[0024] Optionally, in step S3, the pretreated high-tungsten alloy tube is fixed on the support of the impregnation machine, vertically immersed in the mixture, kept immersed for 30 seconds, lifted at a uniform speed of 0.5 m / min, and after a 5-minute interval, immersed for another 30 seconds. Then, it is placed horizontally in a clean room and leveled at room temperature for 10-15 minutes. After preheating at 60°C for 10 minutes, it is horizontally fixed in a vacuum oven and heated to 80°C at 2°C / min. It is kept at this temperature for 2 hours and then naturally cooled to 40°C before being removed to obtain the high-tungsten alloy oil sleeve.

[0025] The above-described technical solution of the present invention has at least the following beneficial effects:

[0026] 1. This invention is based on a multi-component high-entropy alloy, achieving excellent corrosion resistance and mechanical properties through the synergistic effect of tungsten, chromium, chromium nitride, and yttrium. Tungsten enhances the alloy's high-temperature resistance and impact resistance; chromium forms a dense passivation film, preventing H2S corrosion and co-forming composite oxides with tungsten, possessing self-healing capabilities; chromium nitride introduces nitrogen to enhance the stability of the passivation film and inhibit anodic dissolution reactions in CO2 corrosion; and yttrium reacts with H2S to form Y2S3 particles, reducing sulfide stress corrosion and refining intermetallic compound grains, thereby improving the alloy's impact resistance and toughness.

[0027] 2. This invention utilizes MoO4 loading. 2- Zeolite microcapsules, combined with 2-methylimidazole ligand and Zn 2+ Formation of metal complexes, enabling MoO4 2- It is distributed within the pores or coating of zeolite. It achieves dual release in response to pH and reactive oxygen species through a polydopamine shell, precisely releasing MoO4 under acidic CO2 conditions and H2S corrosion triggering. 2- MoO4 2- It can inhibit pitting corrosion propagation, generate a MoS2 protective layer, reduce sulfide stress corrosion, repair coating damage, and improve corrosion resistance.

[0028] 3. This invention uses epoxy-modified silicone resin as the coating material for oil pipelines, combining the high adhesion of epoxy resin with the high temperature resistance and corrosion resistance of silicone resin. It can effectively resist corrosive media such as acids, salts, and sulfides. Its excellent high temperature resistance ensures the stability of the coating at high temperatures, avoiding aging and cracking problems under sunlight. At the same time, the coating has excellent waterproof properties, which can prevent moisture and water penetration, avoid water-induced corrosion and expansion, and ensure the long-term durability of the pipeline. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0030] Preparation:

[0031] Dissolve 12 parts of Tris-HCl in 100 parts of deionized water, adjust the pH to 8.5 with hydrochloric acid, and then add 20 parts of dopamine hydrochloride (DA) and stir until homogeneous to obtain a Tris-DA solution.

[0032] Example 1

[0033] 35 parts tungsten, 15 parts chromium, 15 parts nickel, 23.5 parts iron, 6 parts chromium nitride, and 5.5 parts yttrium were ultrasonically cleaned, then crushed to a particle size ≤ 5 mm, and placed in an electric arc furnace, where a vacuum was applied to 10 °C. -3 Argon gas was introduced after Pa, and the temperature was raised to 3500℃ for 80 min of melting with continuous electromagnetic stirring. Then it was poured into a mold, annealed at 700℃ for 10 h, and then air-cooled to obtain a high-tungsten alloy tube. The inner wall of the high-tungsten alloy tube was sandblasted at 0.6 MPa, wiped with acetone, and dried with hot air at 60℃ for 30 min to obtain a pretreated high-tungsten alloy tube.

[0034] Pretreated Na2MoO4 was obtained by ball milling 0.5 parts of Na2MoO4 for 24 h; mixture A was prepared by mixing 1.2 parts of Zn(NO3)2·6H2O, 0.3 parts of pretreated Na2MoO4, 0.1 parts of Ce(NO3)3·6H2O, 0.1 parts of Ga(NO3)3, and 50 parts of methanol evenly and magnetically stirring for 15 min; mixture B was prepared by dissolving 2.6 parts of 2-methylimidazole in 50 parts of methanol and magnetically stirring for 20 min; mixture B was prepared by mixing mixture A and mixture B evenly and then adding hydrogen at a molar concentration of 0.1 mol / L. The pH of the sodium oxide solution was adjusted to 10.0. After magnetic stirring at 500 rpm for 12 h at 25 °C, 10 parts of deionized water were added, and the mixture was stirred for 7 min. The mixture was then centrifuged at 8000 rpm for 12 min, the supernatant was discarded, and the precipitate was collected. The precipitate was washed three times alternately with 20 parts of methanol and 20 parts of deionized water. It was then placed in Tris-DA solution and continuously exposed to ambient oxygen at room temperature for 24 h. Subsequently, it was centrifuged at 2000 rpm for 8 min, the precipitate was collected, washed with deionized water, and then vacuum dried at 50 °C for 24 h to obtain supported MoO4. 2- Zeolite microcapsules.

[0035] Mix 80 parts of epoxy-modified silicone resin and 8 parts of polyamide, premix with magnetic stirring at 300 rpm for 6 minutes, and then add 15 parts of loaded MoO4. 2- Zeolite microcapsules were dispersed by slow stirring at 100 rpm, and 10 parts xylene and 0.1 parts defoamer were added dropwise. After stirring for 5 min, the mixture was sonicated at 20℃ for 20 min, with a 10 s pause every 5 min to obtain a mixture. The mixture was poured into an impregnation tank, with the liquid level covering the area to be coated on the inner wall of the pretreated high-tungsten alloy tube. The tube was fixed on the impregnation machine support and vertically immersed in the mixture for 30 s. The tube was then lifted at a uniform speed of 0.5 m / min. After a 5 min interval, it was immersed for another 30 s. The tube was then placed horizontally in a clean room and leveled at room temperature for 15 min. After preheating at 60℃ for 10 min, it was horizontally fixed in a vacuum oven and heated to 80℃ at 2℃ / min. The temperature was maintained for 2 h, and the tube was naturally cooled to 40℃ before being removed to obtain the high-tungsten alloy oil sleeve.

[0036] Example 2

[0037] 35 parts tungsten, 15 parts chromium, 15 parts nickel, 23.5 parts iron, 6 parts chromium nitride, and 5.5 parts yttrium were ultrasonically cleaned, then crushed to a particle size ≤ 5 mm, and placed in an electric arc furnace, where a vacuum was applied to 10 °C. -3 Argon gas was introduced after Pa, and the temperature was raised to 3500℃ for 30 min of melting with continuous electromagnetic stirring. Then it was poured into a mold, annealed at 700℃ for 10 h, and then air-cooled to obtain a high-tungsten alloy tube. The inner wall of the high-tungsten alloy tube was sandblasted at 0.6 MPa, wiped with acetone, and dried with hot air at 60℃ for 30 min to obtain a pretreated high-tungsten alloy tube.

[0038] Pretreated Na2MoO4 was obtained by ball milling 0.5 parts of Na2MoO4 for 12 h; mixture A was prepared by mixing 1.2 parts of Zn(NO3)2·6H2O, 0.3 parts of pretreated Na2MoO4, 0.1 parts of Ce(NO3)3·6H2O, and 50 parts of methanol evenly and stirring magnetically for 10 min; mixture B was prepared by dissolving 2.6 parts of 2-methylimidazole in 50 parts of methanol and stirring magnetically for 10 min; mixture B was prepared by mixing mixture A and mixture B evenly and then adding sodium hydroxide solution with a molar concentration of 0.1 mol / L. Adjust the pH to 10.0, and after magnetic stirring at 500 rpm for 12 h at 25 °C, add 10 parts of deionized water, stir for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, collect the precipitate, wash the precipitate three times alternately with 20 parts of methanol and 20 parts of deionized water, place it in Tris-DA solution, and continuously contact it with ambient oxygen at room temperature for 24 h. Then centrifuge at 2000 rpm for 5 min, collect the precipitate, wash it with deionized water, and vacuum dry it at 40 °C for 24 h to obtain supported MoO4. 2- Zeolite microcapsules.

[0039] Mix 80 parts of epoxy-modified silicone resin and 8 parts of polyamide, premix with magnetic stirring at 300 rpm for 5 minutes, and then add 10 parts of loaded MoO4. 2-Zeolite microcapsules were dispersed by slow stirring at 100 rpm, and 5 parts xylene and 0.1 parts defoamer were added dropwise. After stirring for 2 min, the mixture was sonicated at 20℃ for 30 min, with a 10 s pause every 5 min to obtain a mixture. The mixture was poured into an impregnation tank, with the liquid level covering the area to be coated on the inner wall of the pretreated high-tungsten alloy tube. The tube was fixed on the impregnation machine support and vertically immersed in the mixture for 30 s. The tube was then lifted at a uniform speed of 0.5 m / min. After a 5 min interval, it was immersed for another 30 s. The tube was then placed horizontally in a clean room and leveled at room temperature for 10 min. After preheating at 60℃ for 10 min, it was horizontally fixed in a vacuum oven and heated to 80℃ at 2℃ / min. The temperature was maintained for 2 h, and the tube was naturally cooled to 40℃ before being removed to obtain the high-tungsten alloy oil sleeve.

[0040] Example 3

[0041] 35 parts tungsten, 15 parts chromium, 15 parts nickel, 23.5 parts iron, 6 parts chromium nitride, and 5.5 parts yttrium were ultrasonically cleaned, then crushed to a particle size ≤ 5 mm, and placed in an electric arc furnace, where a vacuum was applied to 10 °C. -3 Argon gas was introduced after Pa, and the temperature was raised to 3500℃ for 60 min of melting with continuous electromagnetic stirring. Then it was poured into a mold, annealed at 700℃ for 10 h, and then air-cooled to obtain a high-tungsten alloy tube. The inner wall of the high-tungsten alloy tube was sandblasted at 0.6 MPa, wiped with acetone, and dried with hot air at 60℃ for 30 min to obtain a pretreated high-tungsten alloy tube.

[0042] Pretreated Na2MoO4 was obtained by ball milling 0.5 parts of Na2MoO4 for 16 h; mixture A was prepared by mixing 1.2 parts of Zn(NO3)2·6H2O, 0.3 parts of pretreated Na2MoO4, 0.1 parts of Ce(NO3)3·6H2O, 0.1 parts of Ga(NO3)3, and 50 parts of methanol evenly and stirring magnetically for 15 min; mixture B was prepared by dissolving 2.6 parts of 2-methylimidazole in 50 parts of methanol and stirring magnetically for 15 min; mixture B was prepared by mixing mixture A and mixture B evenly and then adding 0.1 mol / L hydroxide solution. The pH of the sodium hydroxide solution was adjusted to 10.0. After magnetic stirring at 500 rpm for 12 h at 25 °C, 10 parts of deionized water were added, and the mixture was stirred for 10 min. The mixture was then centrifuged at 8000 rpm for 15 min, the supernatant was discarded, and the precipitate was collected. The precipitate was washed three times alternately with 20 parts of methanol and 20 parts of deionized water. It was then placed in Tris-DA solution and continuously exposed to ambient oxygen at room temperature for 24 h. Subsequently, it was centrifuged at 2000 rpm for 10 min, the precipitate was collected, washed with deionized water, and then vacuum dried at 60 °C for 24 h to obtain supported MoO4. 2- Zeolite microcapsules.

[0043] Mix 80 parts of epoxy-modified silicone resin and 8 parts of polyamide, premix with magnetic stirring at 300 rpm for 10 min, and then add 12 parts of loaded MoO4. 2- Zeolite microcapsules were dispersed by slow stirring at 100 rpm, and 7 parts xylene and 0.1 parts defoamer were added dropwise. After stirring for 3 min, the mixture was sonicated at 20℃ for 25 min, with a 10 s pause every 5 min to obtain a mixture. The mixture was poured into an impregnation tank, with the liquid level covering the area to be coated on the inner wall of the pretreated high-tungsten alloy tube. The tube was fixed on the impregnation machine support and vertically immersed in the mixture for 30 s. The tube was then lifted at a uniform speed of 0.5 m / min. After a 5 min interval, it was immersed for another 30 s. The tube was then placed horizontally in a clean room and leveled at room temperature for 12 min. After preheating at 60℃ for 10 min, it was horizontally fixed in a vacuum oven and heated to 80℃ at 2℃ / min. The temperature was maintained for 2 h, and the tube was naturally cooled to 40℃ before being removed to obtain the high-tungsten alloy oil sleeve.

[0044] Example 4

[0045] 35 parts tungsten, 15 parts chromium, 15 parts nickel, 23.5 parts iron, 6 parts chromium nitride, and 5.5 parts yttrium were ultrasonically cleaned, then crushed to a particle size ≤ 5 mm, and placed in an electric arc furnace, where a vacuum was applied to 10 °C. -3 Argon gas was introduced after Pa, and the temperature was raised to 3500℃ for 100 min of melting with continuous electromagnetic stirring. Then it was poured into a mold, annealed at 700℃ for 10 h, and then air-cooled to obtain a high-tungsten alloy tube. The inner wall of the high-tungsten alloy tube was sandblasted at 0.6 MPa, wiped with acetone, and dried with hot air at 60℃ for 30 min to obtain a pretreated high-tungsten alloy tube.

[0046] Pretreated Na2MoO4 was obtained by ball milling 0.5 parts of Na2MoO4 for 18 hours; mixture A was prepared by mixing 1.2 parts of Zn(NO3)2·6H2O, 0.3 parts of pretreated Na2MoO4, 0.1 parts of Ce(NO3)3·6H2O, and 50 parts of methanol and stirring magnetically for 18 minutes; mixture B was prepared by dissolving 2.6 parts of 2-methylimidazole in 50 parts of methanol and stirring magnetically for 12 minutes; mixture A and mixture B were then mixed thoroughly, and a 0.1 mol / L sodium hydroxide solution was added to adjust the concentration. Adjust the pH to 10.0, and after magnetic stirring at 500 rpm for 12 h at 25 °C, add 10 parts of deionized water, stir for 8 min, centrifuge at 8000 rpm for 12 min, discard the supernatant, collect the precipitate, wash the precipitate three times alternately with 20 parts of methanol and 20 parts of deionized water, place it in Tris-DA solution, and continuously contact it with ambient oxygen at room temperature for 24 h. Then centrifuge at 2000 rpm for 7 min, collect the precipitate, wash it with deionized water, and vacuum dry it at 50 °C for 24 h to obtain supported MoO4. 2- Zeolite microcapsules.

[0047] Mix 80 parts of epoxy-modified silicone resin and 8 parts of polyamide, premix with magnetic stirring at 300 rpm for 5 minutes, and then add 11 parts of loaded MoO4. 2- Zeolite microcapsules were dispersed by slow stirring at 100 rpm, and 6 parts xylene and 0.1 parts defoamer were added dropwise. After stirring for 4 min, the mixture was sonicated at 20℃ for 25 min, with a 10-second pause every 5 min to obtain a mixture. The mixture was poured into an impregnation tank, with the liquid level covering the area to be coated on the inner wall of the pretreated high-tungsten alloy tube. The tube was fixed on the impregnation machine support and vertically immersed in the mixture for 30 s. The tube was then lifted at a uniform speed of 0.5 m / min. After a 5-minute interval, it was immersed for another 30 s. The tube was then placed horizontally in a clean room and leveled at room temperature for 15 min. After preheating at 60℃ for 10 min, it was horizontally fixed in a vacuum oven and heated to 80℃ at 2℃ / min. The temperature was maintained for 2 h, and the tube was naturally cooled to 40℃ before being removed to obtain the high-tungsten alloy oil sleeve.

[0048] Example 5

[0049] 35 parts tungsten, 15 parts chromium, 15 parts nickel, 23.5 parts iron, 6 parts chromium nitride, and 5.5 parts yttrium were ultrasonically cleaned, then crushed to a particle size ≤ 5 mm, and placed in an electric arc furnace, where a vacuum was applied to 10 °C. -3 Argon gas was introduced after Pa, and the temperature was raised to 3500℃ for 80 min of melting with continuous electromagnetic stirring. Then it was poured into a mold, annealed at 700℃ for 10 h, and then air-cooled to obtain a high-tungsten alloy tube. The inner wall of the high-tungsten alloy tube was sandblasted at 0.6 MPa, wiped with acetone, and dried with hot air at 60℃ for 30 min to obtain a pretreated high-tungsten alloy tube.

[0050] Pretreated Na2MoO4 was obtained by ball milling 0.5 parts of Na2MoO4 for 15 h; mixture A was prepared by mixing 1.2 parts of Zn(NO3)2·6H2O, 0.3 parts of pretreated Na2MoO4, 0.1 parts of Ce(NO3)3·6H2O, 0.1 parts of Ga(NO3)3, and 50 parts of methanol evenly and stirring magnetically for 20 min; mixture B was prepared by dissolving 2.6 parts of 2-methylimidazole in 50 parts of methanol and stirring magnetically for 12 min; mixture B was prepared by mixing mixture A and mixture B evenly and then adding hydrogen at a molar concentration of 0.1 mol / L. The pH of the sodium oxide solution was adjusted to 10.0. After magnetic stirring at 500 rpm for 12 h at 25 °C, 10 parts of deionized water were added, and the mixture was stirred for 6 min. The mixture was then centrifuged at 8000 rpm for 14 min, the supernatant was discarded, and the precipitate was collected. The precipitate was washed three times alternately with 20 parts of methanol and 20 parts of deionized water. It was then placed in Tris-DA solution and continuously exposed to ambient oxygen at room temperature for 24 h. Subsequently, it was centrifuged at 2000 rpm for 9 min, the precipitate was collected, washed with deionized water, and then vacuum dried at 45 °C for 24 h to obtain supported MoO4. 2- Zeolite microcapsules.

[0051] Mix 80 parts of epoxy-modified silicone resin and 8 parts of polyamide, premix with magnetic stirring at 300 rpm for 10 min, and then add 14 parts of loaded MoO4. 2- Zeolite microcapsules were dispersed by slow stirring at 100 rpm, and 10 parts xylene and 0.1 parts defoamer were added dropwise. After stirring for 5 min, the mixture was sonicated at 20℃ for 20 min, with a 10 s pause every 5 min to obtain a mixture. The mixture was poured into an impregnation tank, with the liquid level covering the area to be coated on the inner wall of the pretreated high-tungsten alloy tube. The tube was fixed on the impregnation machine support and vertically immersed in the mixture for 30 s. The tube was then lifted at a uniform speed of 0.5 m / min. After a 5 min interval, it was immersed for another 30 s. The tube was then placed horizontally in a clean room and leveled at room temperature for 12 min. After preheating at 60℃ for 10 min, it was horizontally fixed in a vacuum oven and heated to 80℃ at 2℃ / min. The temperature was maintained for 2 h, and the tube was naturally cooled to 40℃ before being removed to obtain the high-tungsten alloy oil sleeve.

[0052] The present invention also includes comparative examples and related experiments.

[0053] Comparative Example 1

[0054] Compared with Example 5, the only difference is that chromium nitride was not added during the preparation of the high tungsten alloy tube. The other components are completely consistent with the preparation method, and the high tungsten alloy oil casing is finally prepared.

[0055] Comparative Example 2

[0056] Compared with Example 5, the only difference is that yttrium was not added during the preparation of the high-tungsten alloy tube. The other components are completely consistent with the preparation method, and the high-tungsten alloy oil casing is finally prepared.

[0057] Comparative Example 3

[0058] The only difference from Example 5 is that no MoO4-supported material was prepared. 2- Zeolite microcapsules, with other components prepared in the same manner as the method, were used to finally prepare a high-tungsten alloy oil casing.

[0059] Performance testing

[0060] The yield strength, tensile strength, elongation, yield ratio, and impact energy at -10℃ of Examples 1 to 5 and Comparative Examples 1 to 3 were tested in accordance with the national standard GB / T37701-2019. The specific test results are shown in Table 1.

[0061] Table 1

[0062]

[0063] As shown in Table 1, the relevant properties of Examples 1-5 are significantly better than those of Comparative Examples 1-3. Among them, Comparative Example 1, which did not add chromium nitride, had significantly lower yield strength and tensile strength than Example 1. Comparative Example 2, which did not add yttrium, had significantly lower impact energy than Example 1. The addition of yttrium can refine the grains and significantly improve low-temperature toughness by adsorbing sulfides through the formation of Y2O3 nanoparticles.

[0064] To better test the CO2 / H2S corrosion resistance of Examples 1-5 and Comparative Examples 1-3, samples were prepared according to the JB / T7901-2023 Laboratory Uniform Corrosion Immersion Test Method for Metallic Materials. The samples were fixed in a fixture and placed in an autoclave. 4L of simulated oilfield solution was injected, and the autoclave was sealed. The solution was deoxygenated with N2 for at least 4 hours. After deoxygenation, the temperature was raised. Once the autoclave temperature reached the predetermined temperature, test gas was introduced to the test pressure according to the test conditions: test temperature 70℃, pH = 5, CO2 partial pressure 2.0 MPa, H2S partial pressure 2.0 MPa, and test period 120 hours. Then, N2 was introduced to increase the pressure to the required total test pressure, and timing began. After the test, N2 was introduced for at least 2 hours to remove any remaining gas in the autoclave, and then the samples were removed for analysis.

[0065] After removing the sample, the corrosion products on the sample surface were removed with a film-removing solution, followed by rinsing with running water, dehydration with alcohol, and drying with cold air. The sample was then weighed using an electronic balance, accurate to 0.001 g. The uniform corrosion rate was calculated using the following formula.

[0066]

[0067] In the formula, r cThe corrosion rate is uniform, mm / a; W is the mass difference of the sample before and after the experiment, g; S is the total area of ​​the scraper, cm². 2 ρ is the density of the scraper material, in g / cm³. 3 t represents the experimental time, in hours. The resistance to CO2 / H2S corrosion was evaluated based on the uniform corrosion rate of the samples and their appearance after testing. The results are shown in Table 2.

[0068] Table 2

[0069] project Uniform corrosion rate (mm / a) Appearance Example 1 0.016 No obvious signs of corrosion Example 2 0.018 No obvious signs of corrosion Example 3 0.015 No obvious signs of corrosion Example 4 0.019 No obvious signs of corrosion Example 5 0.014 No obvious signs of corrosion Comparative Example 1 0.085 Corrosion occurs, and the passivation film peels off. Comparative Example 2 0.086 Corrosion and obvious cracks have appeared. Comparative Example 3 0.088 Corrosion occurs, and the coating peels off.

[0070] As shown in Table 2, the uniform corrosion rates of Examples 1-5 were significantly lower than those of Comparative Examples 1-3, indicating that chromium nitride, yttrium, and supported MoO4 were significantly reduced. 2- The addition of zeolite microcapsules can effectively block CO2 / H2S corrosion, which significantly improves the CO2 / H2S corrosion resistance of the samples. In addition, after testing, the samples of Examples 1 to 5 showed no obvious signs of corrosion, which further illustrates that the high tungsten alloy oil casing prepared according to the test method of the present invention has excellent CO2 / H2S corrosion resistance.

[0071] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-tungsten alloy oil casing, characterized in that, Includes the following steps: 35 parts tungsten, 15 parts chromium, 15 parts nickel, 23.5 parts iron, 6 parts chromium nitride, and 5.5 parts yttrium were ultrasonically cleaned, then crushed to a particle size ≤ 5 mm, and placed in an electric arc furnace, where a vacuum was applied to 10 °C. -3 After Pa, argon gas is introduced and the temperature is raised to 3500℃ for 60 min of melting, during which electromagnetic stirring is continuously carried out. Then, it is poured into a mold, annealed at 700℃ for 10 h, and then air-cooled to obtain a high tungsten alloy tube. The inner wall of the high tungsten alloy tube is sandblasted at 0.6 MPa, wiped with acetone, and dried with hot air at 60℃ for 30 min to obtain a pretreated high tungsten alloy tube. Pretreated Na2MoO4 was obtained by ball milling 0.5 parts of Na2MoO4 for 16 h; mixture A was prepared by mixing 1.2 parts of Zn(NO3)2·6H2O, 0.3 parts of pretreated Na2MoO4, 0.1 parts of Ce(NO3)3·6H2O, 0.1 parts of Ga(NO3)3, and 50 parts of methanol evenly and stirring magnetically for 15 min; mixture B was prepared by dissolving 2.6 parts of 2-methylimidazole in 50 parts of methanol and stirring magnetically for 15 min; mixture B was prepared by mixing mixture A and mixture B evenly and then adding 0.1 mol / L hydroxide solution. The pH of the sodium hydroxide solution was adjusted to 10.

0. After magnetic stirring at 500 rpm for 12 h at 25 °C, 10 parts of deionized water were added, and the mixture was stirred for 10 min. The mixture was then centrifuged at 8000 rpm for 15 min, the supernatant was discarded, and the precipitate was collected. The precipitate was washed three times alternately with 20 parts of methanol and 20 parts of deionized water. It was then placed in Tris-DA solution and continuously exposed to ambient oxygen at room temperature for 24 h. Subsequently, it was centrifuged at 2000 rpm for 10 min, the precipitate was collected, washed with deionized water, and then vacuum dried at 60 °C for 24 h to obtain supported MoO4. 2- Zeolite microcapsules; Mix 80 parts of epoxy-modified silicone resin and 8 parts of polyamide, premix with magnetic stirring at 300 rpm for 10 min, and then add 12 parts of loaded MoO4. 2- Zeolite microcapsules were dispersed by slow stirring at 100 rpm, and 7 parts xylene and 0.1 parts defoamer were added dropwise. After stirring for 3 min, the mixture was sonicated at 20℃ for 25 min, with a 10 s pause every 5 min to obtain a mixture. The mixture was poured into an impregnation tank, with the liquid level covering the area to be coated on the inner wall of the pretreated high-tungsten alloy tube. The tube was fixed on the impregnation machine support and vertically immersed in the mixture for 30 s. The tube was then lifted at a uniform speed of 0.5 m / min. After a 5 min interval, it was immersed for another 30 s. The tube was then placed horizontally in a clean room and leveled at room temperature for 12 min. After preheating at 60℃ for 10 min, it was horizontally fixed in a vacuum oven and heated to 80℃ at 2℃ / min. The temperature was maintained for 2 h, and the tube was naturally cooled to 40℃ before being removed to obtain a high-tungsten alloy oil sleeve. The Tris-DA solution was prepared by dissolving 12 parts of Tris-HCl in 100 parts of deionized water, adjusting the pH to 8.5 with hydrochloric acid, and then adding 20 parts of dopamine hydrochloride and stirring until homogeneous.

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