Anti-corrosion and wear-resistant oil pipe with inner coating

Abstract

The utility model relates to the technical field of oil and gas exploitation, in particular to an inner coating anti-corrosion and wear-resistant oil pipe which comprises a base pipe and a composite coating. The composite coating is coated on the inner wall of the base tube; the surface of the inner wall of the base tube is provided with a microcosmic zigzag structure; the composite coating comprises a bottom layer, a middle layer and a surface layer, the bottom layer is attached to the inner wall of the base tube; the middle layer is arranged between the bottom layer and the surface layer; and the surface layer is exposed at the outer end and is in direct contact with a medium conveyed by the oil pipe.

Description

Technical Field

[0001] This application relates to the field of oil and gas extraction technology, and in particular to an internally coated anti-corrosion and wear-resistant oil pipe. Background Technology

[0002] Traditional oil pipes are prone to chemical corrosion and mechanical wear on their inner walls when transporting corrosive media (such as H2S, CO2, and brine) or fluids with high sand content. This can lead to pipe wall thinning, perforation, and even leaks. Current technologies use single epoxy resin coatings or nano-coatings for some oil pipes, but these suffer from insufficient adhesion, poor density, poor high-temperature resistance, and limited wear resistance. Therefore, there is an urgent need for a composite-coated oil pipe that combines high adhesion, corrosion resistance, wear resistance, and impact resistance. Utility Model Content

[0003] The purpose of this application is to provide an internally coated anti-corrosion and wear-resistant oil pipe to solve at least one of the technical problems existing in the prior art.

[0004] To solve the above-mentioned technical problems, this application provides an internally coated anti-corrosion and wear-resistant oil pipe, including a base pipe and a composite coating;

[0005] The composite coating is applied to the inner wall of the base tube.

[0006] Furthermore, the inner wall surface of the base tube is provided with a micro-serrated structure.

[0007] Furthermore, the composite coating comprises a base layer, an intermediate layer, and a top layer;

[0008] The bottom layer is attached to the inner wall of the base tube;

[0009] The intermediate layer is disposed between the bottom layer and the top layer;

[0010] The surface layer is exposed at the outer end and comes into direct contact with the medium transported by the tubing.

[0011] Furthermore, the underlying layer comprises nanoparticles and a coated resin;

[0012] At the contact point between the bottom layer and the surface layer of the base tube, the coating resin penetrates into the serrated structure of the inner wall of the base tube, and forms a barbed structure after curing;

[0013] The nanoparticles are embedded in the interior, inner surface and outer surface of the coated resin, and the nanoparticles on the inner surface contact the base tube to form a pinning effect;

[0014] The nanoparticles on the outer surface form a microscopic uneven structure.

[0015] Furthermore, the intermediate layer comprises hard microparticles and a soft matrix;

[0016] The hard microparticles are wrapped by the elastic network of the soft matrix, forming a "soft-hard" composite structure;

[0017] The soft matrix penetrates into the microscopic uneven structure and forms a mechanical interlocking after curing.

[0018] Furthermore, the surface layer comprises a scale structure and a hydrophobic matrix;

[0019] The scale structure is disposed at one end of the hydrophobic matrix away from the intermediate layer, for direct contact with the medium and reduction of surface friction.

[0020] The hydrophobic matrix contacts and connects with the soft matrix, reducing interfacial stress.

[0021] Furthermore, the base pipe is made of carbon steel oil pipe.

[0022] Furthermore, the thickness of the bottom layer is 50-80 μm.

[0023] Furthermore, the nanoparticles are made of nano-silica particles, accounting for 5-10 wt%;

[0024] The coating resin is made of epoxy phenolic resin.

[0025] Furthermore, the thickness of the intermediate layer is 100-150 μm.

[0026] Furthermore, the material of the hard microparticles is silicon carbide;

[0027] The hard microparticles have a particle size of 10-30 μm and account for 20-30 wt%.

[0028] The soft matrix is ​​made of polyurethane.

[0029] Furthermore, the thickness of the surface layer is 30-50 μm.

[0030] Furthermore, the material of the scale structure is PTFE nanoparticles;

[0031] The scale structure accounts for 5-8 wt%;

[0032] The hydrophobic matrix is ​​made of fluorocarbon resin. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the internal coating structure of the internal coating anti-corrosion and wear-resistant oil pipe disclosed in this application;

[0035] Figure 2 This is a detailed schematic diagram of the inner coating structure.

[0036] Figure label:

[0037] 1-Base tube; 2-Composite coating; 3-Serrated structure; 4-Underlayer; 5-Intermediate layer; 6-Top layer; 7-Nano particles; 8-Coating resin; 9-Uneven structure; 10-Hard particles; 11-Soft matrix; 12-Scale structure; 13-Hydrophobic matrix. Detailed Implementation

[0038] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] It should also be noted that the specific embodiments or implementation methods described below are a series of optimized settings listed in this application to further explain the specific application content, and these settings can be combined or used in conjunction with each other.

[0042] The present application will be further explained below with reference to specific implementation methods.

[0043] like Figure 1-2 As shown in the figure, the internally coated anti-corrosion and wear-resistant oil pipe provided in this embodiment is characterized by comprising a base pipe 1 and a composite coating 2;

[0044] The composite coating 2 is applied to the inner wall of the base tube 1;

[0045] The inner wall surface of the base tube 1 is provided with a micro-serrated structure 3;

[0046] The composite coating 2 includes a base layer 4, an intermediate layer 5, and a top layer 6;

[0047] The bottom layer 4 is attached to the inner wall of the base tube 1;

[0048] The intermediate layer 5 is disposed between the bottom layer 4 and the top layer 6;

[0049] The outer layer 6 is exposed at its outer end and comes into direct contact with the medium transported by the oil pipe.

[0050] The internally coated anti-corrosion and wear-resistant oil pipe disclosed in this application preferably uses a carbon steel oil pipe as the base pipe 1. The roughness Ra is increased to ≥50μm through sandblasting, forming an uneven micro-surface (serrated structure 3) on the surface. This maintains the surface cleanliness Sa of the base pipe 1 at grade 2.5, free of oil and oxides. A composite surface layer 6, comprising a bottom layer 4, an intermediate layer 5, and a top layer 6, is applied to the base pipe 1. This multi-layer composite coating 2 structure significantly improves the corrosion resistance, wear resistance, and service life of the oil pipe, making it suitable for oil and gas transportation under harsh operating conditions.

[0051] As a further embodiment of this example, the bottom layer 4 includes nanoparticles 7 and a coating resin 8;

[0052] At the contact point between the bottom layer 4 and the surface of the base tube 1, the coating resin 8 penetrates into the serrated structure 3 on the inner wall of the base tube 1, and forms a barbed structure after curing.

[0053] The nanoparticles 7 are embedded in the interior, inner surface and outer surface of the coated resin 8, and the nanoparticles 7 on the inner surface contact the base tube 1 to form a pinning effect;

[0054] The nanoparticles 7 on the outer surface form a microscopic uneven structure 9.

[0055] In practical use, the internally coated anti-corrosion and wear-resistant oil pipe disclosed in this application preferably has a base layer 4 with a thickness of 50-80 μm. The nanoparticles 7 are made of nano-silica particles, accounting for 5-10 wt%; the coating resin 8 is made of epoxy phenolic resin. At the connection between the base layer 4 and the base pipe 1, the epoxy phenolic resin penetrates into the sawtooth structure 3 formed by sandblasting of the base pipe 1, and forms a barbed structure after curing. The nano-silica particles are embedded in the epoxy phenolic resin, forming a "pinning effect" on the side in contact with the base pipe 1 (i.e., the nanoparticles are anchored to the surface of the base pipe 1 like nails). The nano-silica can also inhibit electrochemical corrosion through physical filling and chemical passivation. Combined with the dense structure and water and oxygen-blocking epoxy phenolic resin, it can effectively protect the base pipe 1 from corrosion. The silica particles distributed in the epoxy phenolic resin can also disperse stress concentration and prevent crack initiation. Furthermore, the hydroxyl groups of the epoxy phenolic resin used form hydrogen bonds with metal oxides such as iron(III) oxide on the surface of the base tube 1, further strengthening the connection between the bottom layer 4 and the base tube 1. Regarding the matching of thermal expansion coefficients, the overall thermal expansion coefficient of the bottom layer 4 (CTE≈5×10⁻⁶) is adjusted using nanoparticles. -6 / ℃), close to the metal matrix (CTE≈12×10 -6 / ℃), reducing interfacial cracking caused by thermal stress. In terms of the synergy between temperature and chemical stability, the high temperature resistance (≤200℃) of phenolic resin maintains the overall structural stability of the coating.

[0056] As a further embodiment of this example, the intermediate layer 5 includes hard microparticles 10 and a soft matrix 11;

[0057] The hard microparticles 10 are wrapped by the elastic network of the soft matrix 11 to form a "soft-hard" composite structure;

[0058] The soft matrix 11 penetrates into the micro-uneven structure 9 and forms a mechanical interlocking after curing.

[0059] In practical use, the internally coated anti-corrosion and wear-resistant oil pipe disclosed in this application preferably uses an intermediate layer 5 with a thickness of 100-150 μm. The hard microparticles 10 are made of silicon carbide; the particle size of the hard microparticles 10 is 10-30 μm, accounting for 20-30 wt%; the soft matrix 11 is made of polyurethane. The polyurethane matrix elastic network encapsulates the silicon carbide, forming a "soft-hard" composite structure, while the silicon carbide microparticles are uniformly dispersed in the polyurethane matrix to form "hard islands" (similar to pebbles embedded in a rubber matrix). In terms of corrosion resistance, the silicon carbide forms a labyrinth effect in the polyurethane matrix, which can prolong the diffusion path of corrosive media. Liquid polyurethane penetrates into the micro-uneven structure 9 on the surface of the bottom layer 4, and forms a mechanical interlocking after curing. When subjected to impact, the polyurethane absorbs impact energy through elastic deformation; the silicon carbide microparticles form a hard phase to resist abrasive cutting. Furthermore, the -NCO groups of the polyurethane react with the -OH groups of the underlying epoxy phenolic resin to form urethane bonds (-NH-COO-), further strengthening the interlayer bonding. Regarding the matching of thermal expansion coefficients, the thermal expansion coefficient CTE of the intermediate layer 5 is approximately 8 × 10⁻⁶. -6 / ℃, located between the bottom layer 4 and the top layer 6, buffers interlayer stress caused by temperature changes. In terms of the synergy between temperature and chemical stability, the flexibility of polyurethane compensates for the dimensional differences between the top layer 6 and the bottom layer 4 caused by temperature changes.

[0060] As a further embodiment of this example, the surface layer 6 includes a scale structure 12 and a hydrophobic substrate 13;

[0061] The scale structure 12 is disposed at one end of the hydrophobic matrix 13 away from the intermediate layer 5, and is used to directly contact the medium and reduce surface friction.

[0062] The hydrophobic matrix 13 contacts and connects with the soft matrix 11, reducing interfacial stress.

[0063] In practical use, the internally coated anti-corrosion and wear-resistant oil pipe disclosed in this application preferably has a surface layer 6 with a thickness of 30-50 μm. The flake structure 12 is made of PTFE nanoparticles, which are chemically inert and thus resist acidic media corrosion; the proportion of the flake structure 12 is 5-8 wt%; the hydrophobic matrix 13 is made of fluorocarbon resin, which has the characteristics of high cross-linking and strong hydrophobicity, and its contact angle is greater than 110 degrees, which can effectively prevent media adhesion. When dealing with impact, the low coefficient of friction (≤0.15) of the surface layer 6 can reduce the impact of external frictional stress on the underlying layer. In addition, the -CF2 groups of the fluorocarbon resin form weak bonds with the -NH groups of the polyurethane in the intermediate layer 5, reducing interfacial stress and further strengthening the interlayer bonding ability. In terms of temperature and chemical stability, the fluorocarbon resin can resist oxidative degradation at high temperatures, protecting the underlying layer from thermal aging. The PTFE nanoparticles selected in this embodiment also have self-lubricating properties, which can reduce the accumulation of frictional heat and avoid interlayer delamination caused by thermal stress.

[0064] In this embodiment, the curing temperature of the composite coating 2 changes gradually from the bottom layer 4 to the middle layer 5 to the top layer 6, avoiding internal stress caused by excessive temperature difference between layers. Regarding the elastic modulus, the elastic modulus of each layer material in this embodiment also changes gradually, specifically 45 GPa for the bottom layer, 53 GPa for the middle layer, and 61.5 GPa for the top layer, thus allowing the stress to transition smoothly along the coating thickness direction.

[0065] As a further embodiment of this example, a silane coupling agent (preferably KH-550) is also provided between the bottom layer 4, the intermediate layer 5 and the top layer 6. The silane coupling agent can bridge the organic / inorganic interfaces of different coatings through -Si-O- bonds.

[0066] The following is a specific implementation method and test results disclosed in this embodiment.

[0067] In this embodiment, the base tube 1 is made of N80 steel with an inner diameter of 62mm;

[0068] The bottom layer 4 is epoxy phenolic resin + 8% nano silica, with a spraying thickness of 60μm;

[0069] The intermediate layer 5 is polyurethane + 25% silicon carbide microparticles, with a spraying thickness of 120μm;

[0070] Topcoat 6 is made of fluorocarbon resin + 6% PTFE, with a coating thickness of 40μm;

[0071] Test results: No pitting corrosion was observed after 2000 hours of continuous operation in a medium containing 15% NaCl and 0.5% HS, and the coefficient of friction decreased to 0.12.

[0072] This application also discloses a manufacturing process for an internally coated anti-corrosion and wear-resistant oil pipe, including the following steps:

[0073] S1: The base pipe is brought online and thermally cleaned;

[0074] S2: Sandblasting, rust removal and soot blowing are performed on the inner wall of the base pipe;

[0075] S3: Apply the primer and cure;

[0076] S4: Spray the intermediate layer and cure;

[0077] S5: Spray the topcoat and cure;

[0078] S6; Conduct leak detection and finished product inspection. After passing the inspection, mark and put the product into the warehouse.

[0079] By adopting the above technical solution, this application has the following beneficial effects:

[0080] (1) Through the multi-layer composite coating 2 structure design, and the synergistic effect of the bottom 4 nanometer silica particles and epoxy phenolic resin, electrochemical corrosion is effectively suppressed, water and oxygen penetration is blocked, the diffusion path of corrosive media is extended, and the oil pipe can operate for a long time in harsh media environment without pitting corrosion, which significantly enhances the corrosion resistance of the oil pipe.

[0081] (2) The middle layer 5 has a “soft-hard” composite structure. When subjected to impact, the polyurethane elastic deformation absorbs energy, and the silicon carbide microparticles resist abrasive cutting. The surface layer 6 has PTFE nanoparticles with self-lubricating properties, which reduces the accumulation of frictional heat and reduces the impact of external frictional stress on the lower layer, thus improving the overall wear resistance of the oil pipe.

[0082] (3) The multi-layer composite coating structure and the good bonding ability between each layer effectively disperse stress concentration, avoid crack initiation, reduce interface cracking caused by thermal stress, improve the stability of the oil pipe under harsh working conditions, and thus extend the service life of the oil pipe.

[0083] (4) The bottom layer 4 resin penetrates into the base tube 1 serrated structure 3 to form a barbed structure, and the nanoparticles 7 form a pinning effect; the middle layer 5 soft matrix 11 penetrates into the bottom layer 4 micro-concave and convex structure 9 to form mechanical interlocking, and the bonding ability between each layer is further strengthened by chemical bonding; at the same time, silane coupling agent is set to bridge the interfaces of different coatings, effectively reducing the interface stress and making the bonding between each layer more solid.

[0084] (5) By adjusting the thermal expansion coefficient of the bottom layer 4 through nanoparticles, the thermal expansion coefficient of the middle layer 5 is between that of the bottom layer 4 and the top layer 6, and the elastic modulus gradient of each layer material is changed, so that the stress is smoothly transitioned along the coating thickness direction. At the same time, the flexibility of polyurethane compensates for the size difference between the top layer 6 and the bottom layer 4 caused by temperature changes, which improves the adaptability of the oil pipe to temperature changes and ensures the stability of the overall coating structure.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An internally coated corrosion and wear resistant tubing characterized in that, Including the base pipe and composite coating; The composite coating is applied to the inner wall of the base tube; The inner wall surface of the base tube is provided with a micro-serrated structure; The composite coating comprises a base layer, an intermediate layer, and a top layer; The bottom layer is attached to the inner wall of the base tube; The intermediate layer is disposed between the bottom layer and the top layer; The surface layer is exposed at the outer end and comes into direct contact with the medium transported by the tubing.

2. The internally coated corrosion resistant and wear resistant tubing of claim 1, wherein, The bottom layer comprises nanoparticles and a coating resin; At the contact point between the bottom layer and the surface layer of the base tube, the coating resin penetrates into the serrated structure of the inner wall of the base tube, and forms a barbed structure after curing; The nanoparticles are embedded in the interior, inner surface and outer surface of the coated resin, and the nanoparticles on the inner surface contact the base tube to form a pinning effect; The nanoparticles on the outer surface form a microscopic uneven structure.

3. The internally coated corrosion resistant and wear resistant tubing of claim 2, wherein, The intermediate layer comprises hard microparticles and a soft matrix; The hard microparticles are wrapped by the elastic network of the soft matrix, forming a "soft-hard" composite structure; The soft matrix penetrates into the microscopic uneven structure and forms a mechanical interlocking after curing.

4. The internally coated corrosion resistant and wear resistant tubing of claim 3, wherein, The surface layer includes a scale structure and a hydrophobic matrix; The scale structure is disposed at one end of the hydrophobic matrix away from the intermediate layer, for direct contact with the medium and reduction of surface friction. The hydrophobic matrix contacts and connects with the soft matrix, reducing interfacial stress.

5. The internally coated corrosion resistant and wear resistant tubing of claim 1, wherein, The thickness of the bottom layer is 50-80 μm.

6. The internally coated corrosion resistant and wear resistant tubing of claim 2, wherein, The nanoparticles are made of nano-silica particles, accounting for 5-10 wt%; The coating resin is made of epoxy phenolic resin.

7. The internally coated corrosion resistant and wear resistant tubing of claim 1, wherein, The thickness of the intermediate layer is 100-150 μm.

8. The internally coated corrosion resistant and wear resistant tubing of claim 3, wherein, The material of the hard microparticles is silicon carbide; The hard microparticles have a particle size of 10-30 μm and account for 20-30 wt%. The soft matrix is ​​made of polyurethane.

9. The internally coated corrosion resistant and wear resistant tubing of claim 1, wherein, The thickness of the surface layer is 30-50 μm.

10. The internally coated corrosion resistant and wear resistant tubing of claim 4, wherein, The scale structure is made of PTFE nanoparticles; The scale structure accounts for 5-8 wt%; The hydrophobic matrix is ​​made of fluorocarbon resin.

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