A self-healing anti-corrosion thread sealant with high oxygen concentration and its preparation method

Abstract

The present invention provides a self-healing anti-corrosion thread sealant grease with a high oxygen concentration. Calculated by weight percentage based on 100%, it consists of the following components: 50-60% of a composite base grease, 10-15% of a water-absorbing and swelling resin, 1-2% of polyisobutylene, 1-2% of polymethacrylate, 1-2% of magnetic fluid, 3-6% of a dispersant, 2-3% of acrylated phosphate, 2-4% of expanded graphite powder, and 6-30% of an oxygen generator; meanwhile, the present invention also provides a preparation method of the thread sealant grease. The sealant grease provided by the present invention is a self-healing anti-corrosion thread sealant grease with a high oxygen concentration, which can form an elastoplastic polymer to form a sealing layer on the thread surface and fully fill all possible leakage channels of the thread; it can re-seal cavities and gaps through the self-healing function, and can generate a high oxygen concentration in a closed environment to inhibit thread corrosion.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field pipe rod threads, and particularly relates to a self-healing high-oxygen-concentration anti-corrosion thread sealing grease and a preparation method thereof. Background Art

[0002] Problems such as corrosion and leakage of pipe rod threads are common during the exploitation of crude oil and natural gas. To ensure the integrity and economy of thread joints, oil and gas companies at home and abroad mostly use thread sealing grease.

[0003] In recent years, nanomaterials have been applied to petroleum thread grease, mainly nano anti-friction coatings. Such coatings can reduce the friction coefficient between threads and improve thread galling. However, threads coated with this coating still need to use thread sealing grease. Companies such as Bestolife have developed new thread grease products that combine graphite and other non-metallic additives. This thread grease does not contain any heavy metal compounds and achieves performance equivalent to that of heavy metal thread grease through the interaction of different combinations of synthetic amorphous graphite and other non-toxic materials. Tian Feng et al. from the Engineering Materials Research Institute of China National Petroleum Corporation invented a metal-free environmentally friendly thread grease. Different from traditional API thread grease, this thread grease does not contain any heavy metals, does not pollute the on-site environment, and does not cause harm to the drilling workers using it on-site. At the same time, this thread grease has good lubricity and sealing performance and can completely replace traditional API thread grease containing heavy metals.

[0004] However, with the increasingly harsh development environment and the complexity of downhole environments, the local corrosion caused by the failure of traditional thread sealing grease has seriously affected the safe service of wellbore pipe strings and cannot meet the requirements of major oil and gas companies for stable and increased production. Therefore, regarding thread sealing grease, in-depth research needs to be carried out not only on raw materials, formulations, and their compatibility, but also the entire process should be comprehensively considered to greatly improve the safety and service life of use. Summary of the Invention

[0005] Aiming at the defects of the existing technology, the present invention provides a thread sealing grease and a preparation method thereof, specifically a self-healing high-oxygen-concentration anti-corrosion thread sealing grease, which can re-seal cavities and gaps through a self-healing function and can generate a high-oxygen concentration in a closed environment to inhibit thread corrosion.

[0006] A self-healing high-oxygen-concentration anti-corrosion thread sealing grease, calculated by weight percentage as 100%, is composed of the following components: 50 - 60% of a composite base grease, 10 - 15% of a water-absorbing and swelling resin, 1 - 2% of polyisobutylene, 1 - 2% of polymethacrylate, 1 - 2% of a magnetic fluid, 3 - 6% of a dispersant, 2 - 3% of acrylated phosphate, 2 - 4% of expanded graphite powder, and 6 - 30% of an oxygen generator.

[0007] Preferably, the dispersant, calculated on a weight ratio of 100%, comprises the following components: 5-8% of N,N'-methylenebisacrylamide, 2-5% of ethanolamine, 30-40% of methanol, 50-60% of ε-caprolactone, and 1-2% of stannous octoate.

[0008] Preferably, the water-swellable resin, calculated on a weight ratio of 100%, comprises the following components: 25-30% of water, 20-25% of acrylic acid, 30-35% of 2-acrylamido-2-methylpropanesulfonic acid, 5-10% of reinforcing agent, 5-10% of crosslinking agent, and 2-5% of initiator.

[0009] Preferably, the reinforcing agent is DH-3 reinforcing agent or DH-4 reinforcing agent; the crosslinking agent is dicumyl peroxide; the initiator is diisopropyl peroxydicarbonate or dicyclohexyl peroxydicarbonate.

[0010] Preferably, the composite base ester is composed of the following components: 3.77% of 12-hydroxystearic acid, 0.93% of sebacic acid, 0.17% of boric acid, 0.98% of lithium hydroxide, 34.15% of epoxy resin, and 60% of poly-α-olefin oil.

[0011] Preferably, the oxygen generator is composed of potassium superoxide, calcium hydroxide and soda lime mixed in a weight ratio of 7:1:2.

[0012] Preferably, the expansion multiple of the expanded graphite is 180-200 times.

[0013] Preferably, the magnetic liquid is a perfluorocarbon oil-based magnetic liquid.

[0014] The preparation method of the self-healing high-oxygen-concentration anti-corrosion thread sealing grease comprises the following steps:

[0015] (1) Preparation of the dispersant:

[0016] (11) Add N,N'-methylenebisacrylamide to methanol, dissolve it in deionized water, add ethanolamine thereto under nitrogen protection, react at 45-55 °C for 3.5-5 h, concentrate by rotary evaporation, precipitate with cold acetone at -20 °C, redissolve with deionized water, concentrate by rotary evaporation, precipitate with cold acetone at -20 °C, repeat the dissolution-precipitation 3 times, and then dry in vacuum to obtain a pale yellow viscous liquid;

[0017] (12) Mix the pale yellow viscous liquid and ε-caprolactone, heat up to 130-135 °C under a nitrogen atmosphere, stir evenly, add stannous octoate thereto, react at a constant temperature for 5-6 h, cool to room temperature, dissolve with chloroform, and precipitate with anhydrous ether, repeat the dissolution-precipitation 3 times, and dry in vacuum to obtain a yellow waxy solid, thus obtaining the dispersant;

[0018] (2) Preparation of water-absorbing and swelling resin: Mix water, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and a reinforcing agent, stir evenly, add a 25 wt% NaOH solution to adjust the molar neutralization degree to 40%, then add a crosslinking agent and an initiator, raise the temperature to 45 - 55 °C and react for 2.5 - 4 h, dry, cool, and then crush and granulate, and screen through a 6 - 40 mesh sieve to obtain the water-absorbing and swelling resin;

[0019] (3) Preparation of composite base ester: Mix 12-hydroxystearic acid, sebacic acid, boric acid, and lithium hydroxide, add half of the poly-α-olefin oil as the thickening oil, refine at 215 - 225 °C for 1 - 1.5 h to form a grease, then add epoxy resin to it, add the other half of the poly-α-olefin oil as the blending oil for blending, after dissolution, lower the temperature to 115 - 120 °C, and continue to stir for 1 - 1.5 h to make the materials disperse evenly, and obtain the composite base ester through homogenization, filtration, and vacuum degassing;

[0020] (4) Preparation of thread sealant grease: Add polyisobutene, polymethacrylate, magnetic liquid, dispersant, acrylated phosphate, expanded graphite powder, oxygen generator, and water-absorbing and swelling resin to the composite base grease, stir cyclically at 115 - 120 °C for 3 h, and then perform homogenization treatment through a homogenizer to obtain the thread sealant grease, and store it in a sealed manner.

[0021] Preferably, the vacuum drying is carried out at 40 - 50 °C for 24 h; the drying is carried out at 75 - 80 °C for 2 h.

[0022] Advantages of the present invention:

[0023] The sealant grease provided by the present invention is a self-healing high-oxygen-concentration anti-corrosion thread sealant grease, which can form an elastoplastic polymer, form a sealing layer on the thread surface, fully fill all possible leakage channels of the thread, so that there are no cavities and gaps at the seal; when the sealant grease fails, water enters the cavities and gaps, and the water-absorbing and swelling resin in it absorbs the moisture and expands, blocking the cavities and gaps, and the remaining moisture contacts the oxygen generator to generate a large amount of oxygen, generating a high-oxygen-concentration (greater than or equal to 12 mol / L) environment in the closed space, further inhibiting the corrosion of the metal at the thread. Specific embodiments

[0024] In the embodiments of the present invention, the reinforcing agent used is DH-3 reinforcing agent or DH-4 reinforcing agent produced by Taicang Dahao Plastic Co., Ltd.; the model of the poly-α-olefin oil is PAO65 produced by Chevron Phillips; the magnetic liquid used is a perfluorocarbon oil-based magnetic liquid of Swedish PSEINU Besilu Special Lubricants Co., Ltd.

[0025] Example 1

[0026] 1. A self-healing anti-corrosion thread sealant grease with high oxygen concentration, calculated by weight percentage as 100%, is composed of the following components: 55% of compound base grease, 12% of water-absorbing and swelling resin, 1% of polyisobutylene, 1% of polymethacrylate, 2% of perfluorocarbon oil-based magnetic liquid, 6% of dispersant, 2% of acrylated phosphate, 2% of expanded graphite powder, and 19% of oxygen generator;

[0027] The dispersant, calculated by weight ratio as 100%, includes the following components: 7% of N,N′-methylenebisacrylamide, 3% of ethanolamine, 36% of methanol, 53% of ε-caprolactone, and 1% of stannous octoate;

[0028] The water-absorbing and swelling resin, calculated by weight ratio as 100%, includes the following components: 30% of water, 21% of acrylic acid, 32% of 2-acrylamido-2-methylpropanesulfonic acid, 6% of reinforcing agent, 7% of crosslinking agent, and 4% of initiator; the reinforcing agent is DH-4 reinforcing agent; the crosslinking agent is diisopropylbenzene peroxide; the initiator is diisopropyl peroxydicarbonate;

[0029] The compound base ester is composed of the following components: 3.77% of 12-hydroxystearic acid, 0.93% of sebacic acid, 0.17% of boric acid, 0.98% of lithium hydroxide, 34.15% of epoxy resin, and 60% of poly-α-olefin oil;

[0030] The oxygen generator is composed of a mixture of potassium superoxide, calcium hydroxide, and soda lime with a weight ratio of 7:1:2;

[0031] The expansion multiple of the expanded graphite is 180 - 200 times.

[0032] 2. The preparation method of the self-healing anti-corrosion thread sealant grease with high oxygen concentration includes the following steps:

[0033] (1) Preparation of the dispersant:

[0034] (11) Add N,N′-methylenebisacrylamide to methanol, dissolve it in deionized water, add ethanolamine to it under nitrogen protection, react at 50 °C for 4 h, concentrate by rotary evaporation, precipitate with cold acetone at -20 °C, redissolve with deionized water, concentrate by rotary evaporation, and precipitate with cold acetone at -20 °C again. Repeat the dissolution-precipitation process 3 times, and then vacuum dry at 50 °C for 24 h to obtain a light yellow viscous liquid;

[0035] (12) Mix the light yellow viscous liquid and ε-caprolactone, heat up to 130 °C under a nitrogen atmosphere, stir evenly, add stannous octoate thereto, react at a constant temperature for 6 h, cool to room temperature, dissolve with chloroform, and then precipitate with anhydrous ether. Repeat this dissolution-precipitation process 3 times, and vacuum dry at 50 °C for 24 h to obtain a yellow waxy solid, thus obtaining a dispersant;

[0036] (2)Prepare the water-absorbing and swelling resin: Mix water, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and a reinforcing agent, stir evenly, add a 25 wt% NaOH solution to adjust the molar neutralization degree to 40%, then add a crosslinking agent and an initiator, heat up to 50 °C and react for 3 h, dry at 75 °C for 2 h, cool and then crush and granulate, and screen through a 6-40 mesh sieve to obtain the water-absorbing and swelling resin;

[0037] (3)Prepare the composite base ester: Mix 12-hydroxystearic acid, sebacic acid, boric acid, and lithium hydroxide, add half of the poly-α-olefin oil as the thickening oil, refine at 215 °C for 1.5 h to thicken into a grease, then add epoxy resin thereto, add the other half of the poly-α-olefin oil as the blending oil for blending. After dissolution, lower the temperature to 120 °C and continue to stir for 1.5 h to make the materials disperse evenly, and obtain the composite base ester through homogenization, filtration, and vacuum degassing;

[0038] (4)Prepare the thread sealant grease: Add polyisobutylene, polymethacrylate, perfluorocarbon oil-based magnetic liquid, dispersant, acrylated phosphate, expanded graphite powder, oxygen generator, and water-absorbing and swelling resin to the composite base grease, circulate and stir at 120 °C for 3 h, and then perform homogenization treatment with a homogenizer to obtain the thread sealant grease, store it sealed, and strictly prohibit contact with water.

[0039] Example 2

[0040] 1. A self-healing high-oxygen-concentration anti-corrosion thread sealant grease, calculated by weight percentage as 100%, is composed of the following components: 50% of composite base grease, 10% of water-absorbing and swelling resin, 1% of polyisobutylene, 1% of polymethacrylate, 1% of perfluorocarbon oil-based magnetic liquid, 3% of dispersant, 2% of acrylated phosphate, 2% of expanded graphite powder, and 30% of oxygen generator;

[0041] The dispersant, water-absorbing and swelling resin, composite base ester, oxygen generator, expanded graphite, and perfluorocarbon oil-based magnetic liquid are the same as those in Example 1.

[0042] 2. The preparation method of the self-healing high-oxygen-concentration anti-corrosion thread sealant grease includes the following steps:

[0043] (1)Prepare the dispersant:

[0044] (11) Add N,N'-methylenebisacrylamide to methanol, dissolve it in deionized water, add ethanolamine thereto under nitrogen protection, react at 50 °C for 4 h, concentrate by rotary evaporation, precipitate with cold acetone at -20 °C, redissolve with deionized water, concentrate by rotary evaporation, and precipitate with cold acetone at -20 °C again. Repeat the dissolution-precipitation process three times, and then dry in vacuum at 50 °C for 24 h to obtain a pale yellow viscous liquid;

[0045] (12) Mix the pale yellow viscous liquid and ε-caprolactone, heat up to 130 °C under a nitrogen atmosphere, stir evenly, add stannous octoate thereto, react at a constant temperature for 6 h, cool to room temperature, dissolve with chloroform, and precipitate with anhydrous ether. Repeat the dissolution-precipitation process three times, and dry in vacuum at 50 °C for 24 h to obtain a yellow waxy solid, thus obtaining a dispersant;

[0046] (2) Prepare a water-absorbing and swelling resin: Mix water, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and a reinforcing agent, stir evenly, add a 25 wt% NaOH solution to adjust the molar neutralization degree to 40%, then add a crosslinking agent and an initiator, heat up to 50 °C and react for 3 h, dry at 80 °C for 2 h, cool, and then crush and granulate, and sieve through a 6-40 mesh sieve to obtain the water-absorbing and swelling resin;

[0047] (3) Prepare a composite base grease: Mix 12-hydroxystearic acid, sebacic acid, boric acid, and lithium hydroxide, add half of the poly-α-olefin oil as the thickening oil, refine at 215 °C for 1.5 h to thicken into a grease, then add epoxy resin thereto, add the other half of the poly-α-olefin oil as the blending oil for blending, cool the temperature to 120 °C after dissolution, continue to stir for 1.5 h to make the materials disperse evenly, and obtain the composite base grease through homogenization, filtration, and vacuum degassing;

[0048] (4) Prepare a thread seal grease: Add polyisobutene, polymethacrylate, perfluorocarbon oil-based magnetic liquid, dispersant, acrylated phosphate, expanded graphite powder, oxygen generator, and water-absorbing and swelling resin to the composite base grease, stir cyclically at 115 °C for 3 h, and then perform a homogenization treatment with a homogenizer to obtain the thread seal grease. Seal and store it, and strictly prohibit contact with water.

[0049] Example 3

[0050] 1. A self-healing high-oxygen-concentration anti-corrosion thread seal grease, calculated by weight percentage as 100%, is composed of the following components: 60% of composite base grease, 15% of water-absorbing and swelling resin, 2% of polyisobutene, 2% of polymethacrylate, 2% of perfluorocarbon oil-based magnetic liquid, 6% of dispersant, 3% of acrylated phosphate, 4% of expanded graphite powder, and 6% of oxygen generator;

[0051] The dispersant, water-swellable resin, composite base ester, oxygen generator, expanded graphite, and perfluorocarbon oil-based magnetic liquid are the same as those in Example 1.

[0052] 2. The preparation method of the self-healing high-oxygen-concentration anti-corrosion thread sealant grease is the same as that in Example 1.

[0053] Example 4

[0054] 1. A self-healing high-oxygen-concentration anti-corrosion thread sealant grease, calculated by weight percentage as 100%, is composed of the following components: 55% of composite base grease, 12% of water-swellable resin, 1% of polyisobutylene, 1% of polymethacrylate, 2% of perfluorocarbon oil-based magnetic liquid, 6% of dispersant, 2% of acrylated phosphate, 2% of expanded graphite powder, and 19% of oxygen generator;

[0055] The dispersant, calculated by weight ratio as 100%, includes the following components: 5% of N,N'-methylenebisacrylamide, 4% of ethanolamine, 30% of methanol, 60% of ε-caprolactone, and 1% of stannous octoate;

[0056] The water-swellable resin, calculated by weight ratio as 100%, includes the following components: 25% of water, 25% of acrylic acid, 30% of 2-acrylamido-2-methylpropanesulfonic acid, 5% of reinforcing agent, 10% of crosslinking agent, and 5% of initiator; the reinforcing agent is DH-3 reinforcing agent; the crosslinking agent is dicumyl peroxide; the initiator is dicyclohexyl peroxydicarbonate;

[0057] The composite base ester is composed of the following components: 3.77% of 12-hydroxystearic acid, 0.93% of sebacic acid, 0.17% of boric acid, 0.98% of lithium hydroxide, 34.15% of epoxy resin, and 60% of poly-α-olefin oil;

[0058] The oxygen generator and perfluorocarbon oil-based magnetic liquid are the same as those in Example 1;

[0059] The expansion multiple of the expanded graphite is 180 - 200 times.

[0060] 2. The preparation method of the self-healing high-oxygen-concentration anti-corrosion thread sealant grease includes the following steps:

[0061] (1) Preparation of the dispersant:

[0062] (11) Add N,N'-methylenebisacrylamide to methanol, dissolve it in deionized water, add ethanolamine to it under nitrogen protection, react at 45°C for 5 h, concentrate by rotary evaporation, precipitate with -20°C cold acetone, redissolve with deionized water, concentrate by rotary evaporation, and precipitate with -20°C cold acetone again. Repeat this dissolution-precipitation process 3 times, and then vacuum dry at 40°C for 24 h to obtain a pale yellow viscous liquid;

[0063] (12) Mix the light yellow viscous liquid and ε-caprolactone, heat up to 135 °C under a nitrogen atmosphere, stir evenly, add stannous octoate thereto, react at a constant temperature for 5 h, cool to room temperature, dissolve with chloroform, and then precipitate with anhydrous ether. Repeat this dissolution-precipitation process 3 times, and vacuum dry at 40 °C for 24 h to obtain a yellow waxy solid, thus obtaining the dispersant;

[0064] (2) Prepare the water-absorbing and swelling resin: Mix water, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and the reinforcing agent, stir evenly, add a 25 wt% NaOH solution to adjust the molar neutralization degree to 40%, then add the crosslinking agent and the initiator, heat up to 45 °C and react for 4 h, dry at 75 °C for 2 h, cool, and then crush and granulate, and sieve through a 6 - 40 mesh sieve to obtain the water-absorbing and swelling resin;

[0065] (3) Prepare the composite base grease: Mix 12-hydroxystearic acid, sebacic acid, boric acid, and lithium hydroxide, add half of the poly-α-olefin oil as the thickening oil, refine at 225 °C for 1 h to thicken into grease, then add epoxy resin thereto, and add the other half of the poly-α-olefin oil as the blending oil for blending. After dissolution, lower the temperature to 120 °C and continue to stir for 1 h to make the materials disperse evenly, and obtain the composite base grease through homogenization, filtration, and vacuum degassing;

[0066] (4) Prepare the thread seal grease: Add polyisobutene, polymethacrylate, perfluorocarbon oil-based magnetic liquid, dispersant, acrylated phosphate, expanded graphite powder, oxygen generator, and water-absorbing and swelling resin to the composite base grease, circulate and stir at 120 °C for 3 h, and then perform homogenization treatment with a homogenizer to obtain the thread seal grease, store it sealed, and strictly prohibit contact with water.

[0067] Example 5

[0068] 1. A self-healing high-oxygen-concentration anti-corrosion thread seal grease, calculated by weight percentage as 100%, is composed of the following components: 55% of composite base grease, 12% of water-absorbing and swelling resin, 1% of polyisobutene, 1% of polymethacrylate, 2% of perfluorocarbon oil-based magnetic liquid, 6% of dispersant, 2% of acrylated phosphate, 2% of expanded graphite powder, and 19% of oxygen generator;

[0069] The dispersant, calculated by weight ratio as 100%, includes the following components: 6% of N,N′-methylenebisacrylamide, 2% of ethanolamine, 40% of methanol, 50% of ε-caprolactone, and 2% of stannous octoate;

[0070] The water-absorbing and swelling resin, based on 100% by weight, comprises the following components: 28% water, 20% acrylic acid, 35% 2-acrylamido-2-methylpropanesulfonic acid, 10% reinforcing agent, 5% cross-linking agent, and 2% initiator; the reinforcing agent is the same as that in Example 1.

[0071] The composite base ester is composed of the following components: 3.77% 12-hydroxystearic acid, 0.93% sebacic acid, 0.17% boric acid, 0.98% lithium hydroxide, 34.15% epoxy resin, and 60% poly-α-olefin oil.

[0072] The oxygen generator is formed by mixing potassium superoxide, calcium hydroxide, and soda lime in a weight ratio of 7:1:2.

[0073] The expansion multiple of the expanded graphite is 180 - 200 times.

[0074] The perfluorocarbon oil-based magnetic fluid is the same as that in Example 1.

[0075] 2. The preparation method of the self-healing high-oxygen-concentration anti-corrosion thread sealant grease comprises the following steps:

[0076] (1) Preparation of the dispersant:

[0077] (11) Add N,N'-methylenebisacrylamide to methanol, dissolve it in deionized water, add ethanolamine thereto under nitrogen protection, react at 55 °C for 3.5 h, concentrate by rotary evaporation, precipitate with cold acetone at -20 °C, redissolve with deionized water, concentrate by rotary evaporation, and precipitate with cold acetone at -20 °C again. Repeat the dissolution-precipitation process 3 times, and then dry in vacuo at 50 °C for 24 h to obtain a pale yellow viscous liquid.

[0078] (12) Mix the pale yellow viscous liquid with ε-caprolactone, heat up to 135 °C under a nitrogen atmosphere, stir evenly, add stannous octoate thereto, react at a constant temperature for 6 h, cool to room temperature, dissolve with chloroform, and precipitate with anhydrous ether. Repeat the dissolution-precipitation process 3 times, and dry in vacuo at 50 °C for 24 h to obtain a yellow waxy solid, thus obtaining the dispersant.

[0079] (2) Preparation of the water-absorbing and swelling resin: Mix water, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and the reinforcing agent, stir evenly, add a 25 wt% NaOH solution to adjust the molar neutralization degree to 40%, then add the cross-linking agent and the initiator, heat up to 55 °C and react for 2.5 h, dry at 75 °C for 2 h, cool, pulverize and granulate, and screen through a 6 - 40 mesh sieve to obtain the water-absorbing and swelling resin.

[0080] (3) Preparation of the composite base ester: Mix 12 - hydroxy stearic acid, sebacic acid, boric acid, and lithium hydroxide, add half of the polyalpha - olefin oil as the thickening oil, refine at 220 °C for 1 h to form a grease, then add epoxy resin to it, and add the other half of the polyalpha - olefin oil as the blending oil for blending. After dissolution, lower the temperature to 120 °C and continue stirring for 1 h to make the materials disperse evenly. Obtain the composite base ester through homogenization, filtration, and vacuum degassing;

[0081] (4) Preparation of the thread seal grease: Add polyisobutene, polymethacrylate, perfluorocarbon oil - based magnetic fluid, dispersant, acrylated phosphate, expanded graphite powder, oxygen - generating agent, and water - absorbing swelling resin to the composite base grease, stir in a cycle at 120 °C for 3 h, and then perform homogenization treatment through a homogenizer to obtain the thread seal grease. Seal and store it, and strictly prohibit contact with water.

[0082] Comparative Example 1

[0083] Based on Example 1, it does not contain a dispersant, and the weight parts of other components are the same as those in Example 1.

[0084] Performance detection

[0085] 1. Detect the thread seal grease provided by the present invention according to the requirements of API RP 5A3, and the results are shown in Table 1.

[0086] Table 1 Product performance

[0087]

[0088] 2. Oxygen - generating effect detection

[0089] Medium: Oilfield produced water; Oxygen concentration measuring device: Implantable micro - oxygen sensor IMP, Dalian Lidi Fluid Control Technology Co., Ltd.; Container: High - and - low - temperature test chamber, model RL - A - 150D, Dongguan Ruili Testing Equipment Co., Ltd.;

[0090] Detection steps: implant 10 micro - oxygen sensors into 300 ml of thread seal grease, then pour the thread seal grease into a 2 L beaker filled with oilfield produced water, with the volume of the produced water covering the thread seal grease. Place the beaker in the high - and - low - temperature test chamber, and adjust the temperature to 60 °C. Receive the sensor readings every minute and continuously receive them for 12 minutes to detect the oxygen - generating concentration of the seal grease in Example 1. The results are shown in Table 2.

[0091] Table 2 Oxygen - generating concentration

[0092] 。

Claims

1. A self-healing anti-corrosion thread sealant with high oxygen concentration, characterized in that: Calculated according to 100% by weight percentage, it consists of the following components: 50-60% of composite base grease, 10-15% of water-absorbing and swelling resin, 1-2% of polyisobutylene, 1-2% of polymethacrylate, 1-2% of magnetic liquid, 3-6% of dispersant, 2-3% of acrylated phosphate, 2-4% of expanded graphite powder, and 6-30% of oxygen generator.

2. The self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 1, characterized in that: The dispersant, calculated according to 100% by weight ratio, includes the following components: 5-8% of N,N'-methylenebisacrylamide, 2-5% of ethanolamine, 30-40% of methanol, 50-60% of ε-caprolactone, and 1-2% of stannous octoate.

3. The self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 2, characterized in that: The water-absorbing and swelling resin, calculated according to 100% by weight ratio, includes the following components: 25-30% of water, 20-25% of acrylic acid, 30-35% of 2-acrylamido-2-methylpropanesulfonic acid, 5-10% of reinforcing agent, 5-10% of cross-linking agent, and 2-5% of initiator.

4. The self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 3, characterized in that: The reinforcing agent is DH-3 reinforcing agent or DH-4 reinforcing agent; the cross-linking agent is dicumyl peroxide; the initiator is diisopropyl peroxydicarbonate or dicyclohexyl peroxydicarbonate.

5. The self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 3, characterized in that: The composite base ester consists of the following components: 3.77% of 12-hydroxystearic acid, 0.93% of sebacic acid, 0.17% of boric acid, 0.98% of lithium hydroxide, 34.15% of epoxy resin, and 60% of poly-α-olefin oil.

6. The self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 5, characterized in that: The oxygen generator is composed of a mixture of potassium superoxide, calcium hydroxide and soda lime with a weight ratio of 7:1:

2.

7. The self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 6, characterized in that: The expansion multiple of the expanded graphite is 180-200 times.

8. The self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 7, characterized in that: The magnetic liquid is a perfluorocarbon oil-based magnetic liquid.

9. The preparation method of the self-healing anti-corrosion thread sealant with high oxygen concentration according to claim 5, characterized in that: It includes the following steps: (1) Prepare the dispersant: (11) Add N,N'-methylenebisacrylamide to methanol, dissolve it in deionized water, add ethanolamine to it under nitrogen protection, react at 45-55 °C for 3.5-5 h, concentrate by rotary evaporation, precipitate with cold acetone at -20 °C, redissolve with deionized water, concentrate by rotary evaporation, precipitate with cold acetone at -20 °C, repeat the dissolution-precipitation 3 times, and then dry in vacuum to obtain a pale yellow viscous liquid; (12) Mix the light yellow viscous liquid and ε-caprolactone, heat up to 130 - 135 °C under a nitrogen atmosphere, stir evenly, add stannous octoate thereto, react at a constant temperature for 5 - 6 h, cool to room temperature, dissolve with chloroform, then precipitate with anhydrous ether, repeat the dissolution - precipitation 3 times, and dry in vacuum to obtain a yellow waxy solid, thus obtaining the dispersant; (2) Prepare the water - swellable resin: Mix water, acrylic acid, 2 - acrylamido - 2 - methylpropanesulfonic acid, and the reinforcing agent, stir evenly, add 25 wt% NaOH solution to adjust the molar neutralization degree to 40%, then add the cross - linker and initiator, heat up to 45 - 55 °C and react for 2.5 - 4 h, dry by baking, cool, and then crush and granulate, and sieve through a 6 - 40 mesh sieve to obtain the water - swellable resin; (3) Prepare the composite base grease: Mix 12 - hydroxystearic acid, sebacic acid, boric acid, and lithium hydroxide, add half of the poly - α - olefin oil as the thickening oil, refine at 215 - 225 °C for 1 - 1.5 h to thicken into grease, then add epoxy resin thereto, add the other half of the poly - α - olefin oil as the blending oil for blending, after dissolution, lower the temperature to 115 - 120 °C, continue to stir for 1 - 1.5 h to make the materials disperse evenly, and obtain the composite base grease through homogenization, filtration, and vacuum degassing; (4) Prepare the thread seal grease: Add polyisobutylene, polymethacrylate, magnetic liquid, dispersant, acrylated phosphate, expanded graphite powder, oxygen - generating agent, and water - swellable resin to the composite base grease, stir in a cycle at 115 - 120 °C for 3 h, then perform homogenization treatment with a homogenizer to obtain the thread seal grease, store it in a sealed manner, and strictly prohibit contact with water.

10. The preparation method of a self - healing high - oxygen - concentration anti - corrosion thread seal grease according to claim 9, characterized in that: The vacuum drying is carried out at 40 - 50 °C for 24 h in vacuum; the drying by baking is carried out at 75 - 80 °C for 2 h.

Images