Oil well pipe inner wall high temperature resistant anticorrosive coating and preparation method thereof

Abstract

The application provides an oil well pipe inner wall high-temperature-resistant anticorrosive coating and a preparation method thereof. The coating comprises component A and component B. The anticorrosive coating comprises the following components in percentage by weight: component A: polyurethane modified epoxy resin 15-25%; organic silicon resin 5-10%; additive 1-3%; pigment and filler 21-52%; solvent 10-18%; component B: cashew phenol modified amine 10-15%; modified amine prepolymer 2-6.5%; wherein the modified amine prepolymer is prepared from modified fatty amine and modified organosiloxane resin. The anticorrosive coating provided by the application can solve the problem that the oil well pipe of the abandoned oil field needs to be treated before being coated with protective coating in the prior art.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to a high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes and its preparation method. Background Technology

[0002] With the global energy crisis, the supply of new energy sources such as wind and solar power is greatly affected by natural environmental factors, making it difficult to guarantee supply stability. Therefore, the demand for traditional fossil fuels such as oil and natural gas has increased. Furthermore, with the continuous advancement of oil extraction technology, some previously abandoned oil fields need to be put back into operation. These oil fields, having been abandoned for many years, have used old oil well pipes that lack maintenance, resulting in corrosion and rust. Replacing the well pipes is too costly; therefore, the old well pipes are generally reprocessed and put back into use.

[0003] The treatment of waste oil well pipes generally involves applying protective coatings. However, existing protective coatings usually have certain requirements for the surface to be coated. For example, the surface to be coated needs to meet requirements such as surface roughness and cleanliness before coating operations can be carried out. Otherwise, coatings applied to surfaces that do not meet the requirements will lead to problems such as weak coating adhesion and easy peeling, thus failing to achieve the protective effect.

[0004] Surface treatment of waste oil well pipes generally involves various methods such as chemical cleaning, physical cleaning, manual sandblasting, and machine shot blasting. This approach results in high construction costs and low construction efficiency because the waste oil well pipes must undergo surface treatment before painting operations can be carried out. This approach cannot meet the requirements of high-efficiency and fast-paced production projects. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes and its preparation method, which can solve the problem in the prior art that the surface of oil well pipes in abandoned oil fields needs to be treated before a protective coating can be applied when they are put back into use.

[0006] To solve the above-mentioned technical problems, the present invention provides a high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes, comprising component A and component B; wherein, the anti-corrosion coating comprises the following components by weight percentage:

[0007] Component A:

[0008]

[0009] Component B:

[0010] Cashew phenol modified amine 10%-15%;

[0011] Modified amine prepolymers: 2%-6.5%;

[0012] The modified amine prepolymer is prepared from modified aliphatic amines and modified organosiloxane resins.

[0013] Furthermore, the additives include leveling agents, defoamers, dispersants, and anti-settling thickeners.

[0014] Furthermore, the percentage of each component in component A in the additive is as follows: leveling agent 0.2%-0.5%; defoamer 0.2%-0.5%; dispersant 0.4%-0.8%; anti-settling thickener 0.4%-1%.

[0015] Furthermore, the anti-settling thickener comprises fumed silica and polyamide wax powder.

[0016] Furthermore, the pigments and fillers include zinc phosphate, chrome green, aluminum tripolyphosphate, wollastonite powder, and potassium titanate whiskers.

[0017] Furthermore, the percentage of each component in the pigment and filler relative to component A is as follows: zinc phosphate 4%-8%; chrome green 8%-15%; aluminum tripolyphosphate 4%-12%; wollastonite powder 4%-12%; potassium titanate whiskers 1%-5%.

[0018] Furthermore, the solvent is selected from a combination of xylene and propylene glycol methyl ether.

[0019] Furthermore, the epoxy value of the polyurethane-modified epoxy resin is 0.45-0.48; the epoxy value of the modified organosiloxane resin is 0.05-0.1; and the active hydrogen equivalent of the modified amine prepolymer is 145-150.

[0020] Furthermore, the anti-corrosion coating comprises, by weight percentage:

[0021] Component A:

[0022]

[0023] Component B:

[0024] Cashew phenol modified amine 10%-15%;

[0025] Modified amine prepolymers: 2%-6.5%.

[0026] This invention also provides a method for preparing a high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes, comprising the following steps:

[0027] Preparation of component A:

[0028] S1: Add polyurethane-modified epoxy resin and silicone resin to the solvent and stir until homogeneous;

[0029] S2: Add the defoamer, leveling agent and dispersant in sequence while stirring, and stir until homogeneous;

[0030] S3: Add fumed silica to the reaction system of S2 and disperse it evenly;

[0031] S4: Zinc phosphate, aluminum tripolyphosphate, chrome green, wollastonite powder and potassium titanate whiskers are added sequentially to the reaction system of S3 under stirring.

[0032] S5: Add polyamide wax powder to the reaction system of S4 under stirring, mix evenly, and obtain component A;

[0033] Preparation of component B:

[0034] Preparation of modified amine prepolymer: Modified aliphatic amine, modified organosiloxane resin and phosphoric acid are mixed evenly, heated to react, and the reaction system is dispersed to obtain the modified amine prepolymer;

[0035] Weigh out the cashew phenol-modified amine and the modified amine prepolymer, mix them evenly to obtain component B.

[0036] In summary, compared with existing technologies, the high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes provided by this invention uses modified aliphatic amines and modified organosiloxane resins to prepare a modified amine prepolymer, which is then mixed with cashew phenol modified amine in a certain proportion as a curing agent. This curing agent has a good curing effect on polyurethane modified epoxy resin and organosilicon resin. Combined with other auxiliary additives and fillers, the coating can achieve good adhesion, density, and high-temperature corrosion resistance. When applied to the inner wall of abandoned oil well pipes, surface treatment of the inner wall of the oil well pipe is basically unnecessary to achieve good adhesion. The coating will not peel off or crack and has good protective capabilities. Furthermore, when the coating of this invention is applied, the adhesion is excellent, reaching 20-30 MPa, and the glass transition temperature of the coating is above 140°C, giving the coating good high-temperature resistance. In addition, the coating also has excellent acid, alkali, and salt resistance, good corrosion resistance, and maintains excellent performance even when immersed in high-temperature crude oil. It is particularly suitable for the protection of untreated abandoned oil well pipes. Detailed Implementation

[0037] The following detailed description, in conjunction with specific embodiments, provides a high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes and its preparation method, as proposed in this invention. The advantages and features of this invention will become clearer from the following description.

[0038] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The methods described herein comprise a series of steps, and the order of these steps presented herein is not necessarily the only possible order in which they can be performed, and some described steps may be omitted and / or other steps not described herein may be added to the method. It should be noted that, unless otherwise stated, the compound raw materials used in this invention are all commercially available raw materials.

[0039] The purpose of this invention is to provide a high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes and its preparation method, which can solve the problem in the prior art that the surface of oil well pipes in abandoned oil fields needs to be treated before a protective coating can be applied when they are put back into use.

[0040] To achieve the above-mentioned goals, this invention provides a high-temperature resistant and corrosion-resistant coating for the inner wall of oil well pipes, comprising component A and component B;

[0041] The anti-corrosion coating comprises the following components by weight percentage:

[0042] Component A includes:

[0043]

[0044] Component B includes:

[0045] Cashew phenol modified amine 10%-15%;

[0046] Modified amine prepolymers: 2%-6.5%;

[0047] The modified amine prepolymer is prepared from modified aliphatic amines and modified organosiloxane resins. Specifically, the modified amine prepolymer can be prepared from the modified aliphatic amines and modified organosiloxane resins under high temperature reaction conditions with the aid of a catalyst.

[0048] In this invention, a modified amine prepolymer is prepared by using modified aliphatic amines and modified organosiloxane resins. This prepolymer is then mixed with cashew phenol-modified amine in a specific ratio to serve as a curing agent. This curing agent exhibits excellent curing properties for polyurethane-modified epoxy resins and organosilicone resins. Combined with other auxiliary agents and fillers, the coating achieves excellent adhesion, density, and high-temperature corrosion resistance. When applied to the inner wall of abandoned oil well tubing, surface treatment of the tubing is largely unnecessary to achieve good adhesion. The coating does not peel or crack and provides excellent protection. Furthermore, the use of resin-modified prepolymers in this invention results in a glass transition temperature exceeding 140°C, giving the coating excellent high-temperature resistance.

[0049] In the coating of the present invention, the additives include leveling agents, defoamers, dispersants, and anti-settling thickeners. The percentage of each component in component A is as follows: leveling agent 0.2%-0.5%, which may be selected from polyether-modified polydimethylsiloxane leveling agents; defoamer 0.2%-0.5%, which may be modified polysiloxane defoamers containing hydrophobic particles; dispersant 0.4%-0.8%, which may be high molecular weight block copolymer dispersants containing pigment-affinity groups; and anti-settling thickener 0.4%-1%, which may include thickeners composed of hydrophobic fumed silica and polyamide wax powder.

[0050] In this invention, the pigments and fillers may include zinc phosphate, chrome green, aluminum tripolyphosphate, wollastonite powder, and potassium titanate whiskers. The percentage of each component in component A is as follows: zinc phosphate 4%-8%; chrome green 8%-15%; aluminum tripolyphosphate 4%-12%; wollastonite powder 4%-12%; and potassium titanate whiskers 1%-5%.

[0051] In the coating of the present invention, the solvent may be selected from a combination of xylene and propylene glycol methyl ether, with a volume ratio of approximately 3:4 to 5:2.

[0052] In the main raw materials selected in this invention, the epoxy value of the polyurethane modified epoxy resin is 0.45-0.48; the epoxy value of the modified organosiloxane resin is 0.05-0.1; and the active hydrogen equivalent of the modified amine prepolymer is 145-150.

[0053] Preferably, in the coating of the present invention, the anti-corrosion coating comprises, by weight percentage:

[0054] Component A:

[0055]

[0056] Component B:

[0057] Cashew phenol modified amine 10%-15%;

[0058] Modified amine prepolymers: 2%-6.5%.

[0059] Before use, the coating of the present invention is prepared by mixing component A and component B in a mass ratio of A:B = 4.5-5.5:1, and then coating it on the inner wall of the oil well pipe.

[0060] This invention also provides a method for preparing a high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes, comprising the following steps:

[0061] Preparation of component A:

[0062] S1: Add the polyurethane-modified epoxy resin and silicone resin to the solvent and stir until homogeneous; specifically, measure xylene and propylene glycol methyl ether and add them to a clean container, then add the polyurethane-modified epoxy resin and silicone resin, and stir until homogeneous.

[0063] S2: While continuously stirring, add the defoamer, leveling agent and dispersant in sequence, and continue stirring until homogeneous;

[0064] S3: Add fumed silica to the reaction system of S2, increase the rotation speed, and disperse it evenly at high speed;

[0065] S4: Under medium-speed stirring, zinc phosphate, aluminum tripolyphosphate, chrome green, wollastonite powder and potassium titanate whiskers are added sequentially to the reaction system of S3. Then, the stirring speed is increased. When the system temperature reaches about 55°C, the stirring speed is reduced.

[0066] S5: Add polyamide wax powder to the reaction system of S4 under stirring, mix evenly, increase the speed during mixing until the temperature of the mixture reaches 55-60℃ and maintain the temperature for more than 30 minutes, then let the mixture cool down to room temperature to obtain component A. Alternatively, the mixture can be ground to a fineness of ≤60μm to make it finer.

[0067] Preparation of component B:

[0068] Preparation of modified amine prepolymer: Modified aliphatic amine, modified organosiloxane resin and phosphoric acid are mixed evenly in a clean container at a mass ratio of 20:1:0.1. Phosphoric acid is used as a catalyst for the curing agent prepolymerization reaction. The mixture is heated to about 80°C and dispersed at a low speed for about 4 hours. Then, the mixture is cooled to room temperature and dispersed for another 4 hours. The resulting reaction system is the modified amine prepolymer. Then, cashew phenol modified amine and the modified amine prepolymer are weighed and mixed evenly to obtain component B.

[0069] To further understand the present invention, preferred embodiments will be described below in more detail to highlight the characteristics and features of the high-temperature resistant and anti-corrosion coating for the inner wall of oil well pipes provided by the present invention. These descriptions are merely illustrative of the features and advantages of the method of the present invention and are not intended to limit the scope of protection of the present invention.

[0070] Based on the different proportions of the components in the coating, the present invention provides the following three embodiments to describe the formulation composition of high-temperature resistant and anti-corrosion coatings for the inner wall of oil well pipes.

[0071] In the coatings of Examples 1-3, the raw materials of components A and B are the same. The difference lies in the different proportions of the components in each example. The component proportions (parts by weight) of the anti-corrosion coatings in Examples 1-3 are shown in Table 1 below.

[0072] In each embodiment, the raw materials were all commercially available. Xylene and propylene glycol methyl ether were commercially available raw materials. The polyurethane-modified epoxy resin used was CVC's HyPox UA10 polyurethane-modified epoxy resin. The silicone resin used was DOWSIL from Dow Chemical. 2405 resin; leveling agent was BYK358N from BYK Corporation; defoamer was purchased from BYK Corporation, product model BYK054; dispersant was purchased from BYK Corporation, product model BYK163; fumed silica was Degussa's fumed silica A200; polyamide wax powder was purchased from Deqian's MAX model; zinc phosphate, chrome green, and aluminum tripolyphosphate were all purchased from Shanghai Yipin Pigment Co., Ltd.; wollastonite powder was purchased from Jiangxi Aote Technology Co., Ltd.; potassium titanate whiskers were purchased from Jinan Zian Chemical Co., Ltd.; cashew phenol modified amine was Daigao's HD-P41 product; modified fatty amine was Huntsman's Aradur943 product; and modified organosiloxane resin was Dow Corning's RSN-0255 product.

[0073] Table 1. Component ratios of various embodiments of the high-temperature resistant and anti-corrosion coating for the inner wall of oil well pipes.

[0074]

[0075]

[0076] Table 2. Mixing ratio of component A and component B before application of high-temperature resistant anti-corrosion coating for oil well pipe inner wall.

[0077] / Example 1 Example 2 Example 3 Mixing ratio of component A to component B 4.41:1 5.06:1 5.45:1

[0078] Before use, the anti-corrosion coatings of the three embodiments were prepared by mixing component A and component B according to the proportions in Table 3, and then coating them onto the inner wall of the untreated waste oil well pipe to form a coating.

[0079] To verify the performance of the anti-corrosion coatings of Examples 1-3 of the present invention, the coating performance of the coatings in Examples 1 to 3 of the present invention was tested, and existing anti-corrosion coatings for oil well pipes were used as a control group. The coatings of Examples 1-3 and the control group were respectively applied to the inner wall surface of oil well pipes with low surface treatment, and then the performance of the coatings was evaluated to obtain the performance data of the coatings of Examples 1-3 and the control group.

[0080] The existing anti-corrosion coating formulation in the control group is as follows:

[0081] Component A:

[0082]

[0083]

[0084] Component B:

[0085] Cashew phenol modified amine 15%

[0086] Before use, the ratio of component A to component B is 5.7:1.

[0087] When testing the performance of the coating, the coating applied to the inner wall surface of the oil well pipe shall be tested according to the following test items and test standards.

[0088] Adhesion test: Before testing, the coating is subjected to a pull-out adhesion test.

[0089] High temperature and humidity resistance test: Boiling water at 95°C is introduced into the oil well pipe coated with the coating and soaked for more than 1500 hours. The appearance and adhesion of the coating are then observed.

[0090] High-temperature oil resistance test: An oil bath liquid at a temperature of 150°C is introduced into the oil well pipe coated with the coating, and the pipe is immersed in the oil bath liquid for more than 1500 hours. The appearance and adhesion of the coating are then observed.

[0091] Corrosion resistance test: 10% sulfuric acid, 5% sodium hydroxide and 3% sodium chloride solutions were introduced into the pipes coated with the coating, and the pipes were soaked at room temperature for 90 days. The appearance and adhesion of the coating were then observed.

[0092] Routine oil resistance test: Crude oil, gasoline, and diesel are introduced into the pipeline coated with the coating, and the pipeline is immersed at room temperature for 90 days. The appearance and adhesion of the coating are then observed.

[0093] The performance of the coatings in Examples 1-3 and the control group was tested using the above-described testing method, and the results are shown in Table 4 below. Table 4 reflects the performance effects of the coatings in Examples 1-3 and the control group of the present invention.

[0094] Table 4 Comparison of coating performance between the control group and Examples 1-3

[0095]

[0096]

[0097] Through the above comparative tests, we can see that the high-temperature resistant anti-corrosion coating provided by the present invention has superior anti-corrosion performance compared with ordinary coatings in the prior art when applied to the inner wall of oil well pipes with low surface treatment, especially in terms of high-temperature resistance.

[0098] In summary, compared with existing technologies, the high-temperature resistant anti-corrosion coating for the inner wall of oil well pipes provided by this invention uses modified aliphatic amines and modified organosiloxane resins to prepare a modified amine prepolymer, which is then mixed with cashew phenol modified amine in a certain proportion as a curing agent. This curing agent has a good curing effect on polyurethane modified epoxy resin and organosilicon resin. Combined with other auxiliary additives and fillers, the coating can achieve good adhesion, density, and high-temperature corrosion resistance. When applied to the inner wall of abandoned oil well pipes, surface treatment of the inner wall of the oil well pipe is basically unnecessary to achieve good adhesion. The coating will not peel off or crack and has good protective capabilities. Furthermore, when the coating of this invention is applied, the adhesion is excellent, reaching 20-30 MPa, and the glass transition temperature of the coating is above 140°C, giving the coating good high-temperature resistance. In addition, the coating also has excellent acid, alkali, and salt resistance, good corrosion resistance, and maintains excellent performance even when immersed in high-temperature crude oil. It is particularly suitable for the protection of untreated abandoned oil well pipes.

[0099] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure are within the scope of the claims. Obviously, those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations of the invention fall within the scope of the claims and their equivalents, the invention also intends to include these modifications and variations.

Claims

1. A high-temperature resistant and corrosion-resistant coating for the inner wall of oil well pipes, applied to the inner wall of oil well pipes with low surface treatment, characterized in that, It includes component A and component B; wherein, the anti-corrosion coating comprises the following components by weight percentage: Component A includes: Polyurethane-modified epoxy resin 15%-25%; 5%-10% silicone resin; Additives 1%-3%; Pigments and fillers 21%-52%; Solvent 10%-18%; The solvent is selected from a combination of xylene and propylene glycol methyl ether; Component B includes: Cashew phenol modified amine 10%-15%; Modified amine prepolymer 2%-6.5%; The modified amine prepolymer is prepared from modified aliphatic amines and modified organosiloxane resins.

2. The high-temperature resistant anti-corrosion coating for the inner wall of oil well pipe according to claim 1, characterized in that, The additives include leveling agents, defoamers, dispersants, and anti-settling thickeners.

3. The high-temperature resistant anti-corrosion coating for the inner wall of oil well pipe according to claim 2, characterized in that, The percentage of each component in the additives in the anticorrosive coating is as follows: leveling agent 0.2%-0.5%; defoamer 0.2%-0.5%; dispersant 0.4%-0.8%; anti-settling thickener 0.4%-1%.

4. The high-temperature resistant anti-corrosion coating for the inner wall of oil well pipe according to claim 3, characterized in that, The anti-settling thickener includes fumed silica and polyamide wax powder.

5. The high-temperature resistant anti-corrosion coating for the inner wall of oil well pipe according to claim 1, characterized in that, The pigments and fillers include zinc phosphate, chrome green, aluminum tripolyphosphate, wollastonite powder, and potassium titanate whiskers.

6. The high-temperature resistant anti-corrosion coating for the inner wall of oil well pipe according to claim 5, characterized in that, The percentage of each component in the pigments and fillers in the anti-corrosion coating is as follows: zinc phosphate 4%-8%; chrome green 8%-15%; aluminum tripolyphosphate 4%-12%; wollastonite powder 4%-12%; potassium titanate whiskers 1%-5%.

7. The high-temperature resistant anti-corrosion coating for the inner wall of oil well pipe according to claim 1, characterized in that, The epoxy value of the polyurethane-modified epoxy resin is 0.45-0.48; the epoxy value of the modified organosiloxane resin is 0.05-0.1; and the active hydrogen equivalent of the modified amine prepolymer is 145-150.

8. The high-temperature resistant anti-corrosion coating for the inner wall of oil well pipe according to claim 1, characterized in that, The anti-corrosion coating comprises, by weight percentage: Component A: Polyurethane-modified epoxy resin 15%-25%; 5%-10% silicone resin; Leveling agent 0.2%-0.5%; Defoamer 0.2%-0.5%; Dispersant 0.4%-0.8%; Anti-settling thickener 0.4%-1%; Zinc phosphate 4%-8%; Chrome green 8%-15%; Aluminum tripolyphosphate 4%-12%; Wollastonite powder 4%-12%; Potassium titanate whiskers 1%-5%; Xylene 6%-10%; Propylene glycol methyl ether 4%-8%; Component B: Cashew phenol modified amine 10%-15%; Modified amine prepolymer 2%-6.5%.

9. A method for preparing a high-temperature resistant anti-corrosion coating for the inner wall of an oil well pipe as described in any one of claims 1-8, characterized in that, Includes the following steps: Preparation of component A: S1: Add polyurethane-modified epoxy resin and silicone resin to the solvent and stir until homogeneous; S2: Add the defoamer, leveling agent and dispersant in sequence while stirring, and stir until homogeneous; S3: Add fumed silica to the reaction system of S2 and disperse it evenly; S4: Zinc phosphate, aluminum tripolyphosphate, chrome green, wollastonite powder and potassium titanate whiskers are added sequentially to the reaction system of S3 under stirring. S5: Add polyamide wax powder to the reaction system of S4 under stirring, mix evenly, and obtain component A; Preparation of component B: Preparation of modified amine prepolymer: Modified aliphatic amine, modified organosiloxane resin and phosphoric acid are mixed evenly, heated to react, and the reaction system is dispersed to obtain the modified amine prepolymer; Weigh out the cashew phenol-modified amine and the modified amine prepolymer, mix them evenly to obtain component B.

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