A method for on-line repair of flexible composite pipe

Abstract

This invention discloses an online repair method for flexible composite pipes, belonging to the field of online pipeline repair technology. The method includes the following steps: (1) increasing the pressure of the pipeline to be repaired; (2) reducing the pressure at the location of the pipeline to be repaired; and (3) covering the outer surface of the pipeline to be repaired with pre-impregnated tape. The method of this invention uses pre-impregnated tape to bond the defect after adjusting the pressure, ensuring pressure resistance. It can repair corroded pipelines without interrupting the pipe and draining the fluid, resulting in fast repair speed and low cost.

Description

Technical Field

[0001] This invention belongs to the field of pipeline online repair technology, specifically relating to an online repair method for flexible composite pipes. Background Technology

[0002] Non-metallic flexible pipes are increasingly widely used in oil and gas fields. Flexible composite pipes have advantages such as corrosion resistance, low transport resistance, and strong structural design flexibility. Furthermore, single-piece lengths can reach hundreds of meters, reducing the impact of joints on the pipe material. Common flexible composite pipes often employ a three-layer structure. The inner layer is typically a corrosion-resistant and wear-resistant thermoplastic pipe, serving to seal the fluid and block chemical media erosion. The middle layer is a reinforcing layer, composed of continuous fiber-reinforced resin composite material. The outer layer is a protective coating layer, preventing external wear and resisting UV aging, and is usually made of polyethylene.

[0003] During oil and gas extraction, the extracted crude oil and natural gas often come out of the well at high temperatures and contain large amounts of corrosive substances, such as hydrogen sulfide gas and microorganisms, causing severe corrosion to pipelines and equipment and affecting their service life. After prolonged use in oil and gas fields, oil pipes develop scale and rust on their inner walls, forming a rust layer. Furthermore, rust layers also form on the inner and outer walls of oil pipes in water injection wells and surface water injection pipelines after long-term use. Rusting of oil pipes can easily cause the rust layer to flake off, blocking the pipeline; continued corrosion can also cause perforation, leading to oil and gas leaks and safety accidents. Currently, there are two main methods for dealing with failed pipe materials: one is to replace the entire pipeline, which is expensive and consumes a lot of manpower and resources; the other method is to wrap the leaking area with non-metallic materials and then secure it with metal clamps, but this method is prone to re-leakage.

[0004] The literature (Jie Hailin et al., Online Repair Technology of Old Pipelines with Inserted Lining High-Density Polyethylene Pipes [J], Corrosion and Protection, 2002, 23(4): 174-180) discloses a new pipeline repair technology—inserted lining high-density polyethylene pipes. The lining pipe is made of high-density polyethylene (HDPE) pipe with excellent comprehensive performance, and the corrosion resistance, wear resistance, and wear resistance of the repaired pipeline are greatly improved. This technology is suitable for corrosion protection and repair of urban water supply, gas pipelines, oilfield sewage pipelines, and oil-water mixed transportation pipelines.

[0005] Patent CN101469801 discloses an online repair method for corrugated pipes: 1. Rapid leak sealing; 2. Repair surface pretreatment; 3. Repair surface activation treatment; 4. Applying a reinforcing layer; 5. Applying a protective film; 6. Curing: curing at room temperature for 24 hours. The flexible composite adhesive used in the repair has the following composition by weight percentage: 4.7-4.9% vulcanizing paste, 3.3-3.5% alkylphenol resin, 0.45-0.75% 2-mercaptobenzothiazole, 0.10-0.80% (3-γ-triethoxysilylpropyl)tetrasulfide, and the remainder being bulk polysulfide rubber. This method can perform online repair and reinforcement of corrugated pipes in the pipeline network under temperature and pressure without stopping the machine, without open flame. It has the advantages of safety, reliability, environmental protection, and energy saving; the impact on the equipment itself is extremely low, the maintenance cost is far lower than the cost of installing a new corrugated pipe, it expands the scope of multiple repairs, and greatly increases the service life of the equipment.

[0006] Chinese patent application 202010364614.3 discloses a method and structure for repairing defects in a flexible composite pipe. A thermoplastic pipe is located in the defect removal area of ​​the flexible composite pipe. Both ends of the thermoplastic pipe are connected to the inner lining layers at both ends of the removed defect section in the flexible composite pipe. A fiber reinforcement tape is wound around the outside of the thermoplastic pipe, with a thickness greater than the sum of the thicknesses of the reinforcing layer and the outer protective layer of the flexible composite pipe. The repair method involves: removing the defective section from the flexible composite pipe, removing the reinforcing layer and the outer protective layer at both ends of the defective section, exposing the inner lining layer; connecting both ends of the thermoplastic pipe to the two ends of the removed defect section in the flexible composite pipe; and wrapping the thermoplastic pipe and the inner lining layer with fiber reinforcement tape, the thickness of which is greater than the sum of the thicknesses of the reinforcing layer and the outer protective layer of the flexible composite pipe. This reduces the pipe repair cost and ensures the reliability of the repaired area under renewed pressure.

[0007] However, current repair techniques all require disconnecting the pipe and draining the fluid when oil pipes are corroded, which means that repairs can only be carried out after work and production have stopped, affecting oil and gas field production and increasing repair costs.

[0008] In view of this, the present invention provides an online repair method for flexible composite pipes to address the above problems. The method uses prepreg tape to bond the defect to ensure pressure resistance, and can repair corroded pipes without cutting off the pipe and draining the liquid. The repair speed is fast and the cost is low. Summary of the Invention

[0009] The purpose of this invention is to provide an online repair method for flexible composite pipes. After adjusting the pressure, pre-impregnated tape is used to bond the defect to ensure pressure resistance. Corrosion repair can be achieved without cutting the pipe and draining the liquid. The repair speed is fast and the cost is low.

[0010] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0011] This invention provides an online repair method for flexible composite pipes, comprising the following steps:

[0012] (1) Increase the pressure of the pipeline to be repaired;

[0013] (2) Reduce the pressure at the location of the pipeline to be repaired;

[0014] (3) Wrap the outer surface of the pipe to be repaired with prepreg tape.

[0015] Preferably, in step (1), the pressure of the pipeline to be repaired is increased by increasing the amount of gas or liquid introduced into the pipeline to be repaired; more preferably, the introduced gas or liquid enters the pipeline to be repaired along the tangent of the pipeline to be repaired.

[0016] Preferably, the time for increasing the pressure should not exceed 1 minute.

[0017] Preferably, in step (2), the pressure at the location of the pipeline to be repaired is reduced by disconnecting the gas supply or reducing the liquid flow rate.

[0018] Preferably, in step (3), the prepreg tape is bonded to the pipe to be repaired by an adhesive.

[0019] The adhesive can be a conventional adhesive in the art, preferably an epoxy resin-based adhesive.

[0020] Preferably, in step (3), the prepreg tape includes a reinforcing core layer and a surface layer.

[0021] More preferably, the reinforcing core layer includes a radial reinforcing layer and an axial reinforcing layer disposed sequentially from the inside to the outside.

[0022] More preferably, each radial reinforcing layer is formed by obliquely winding a glass fiber prepreg material. Even more preferably, the glass fiber prepreg material is a continuous glass fiber prepreg tape with a thickness of 0.2-0.5 mm, a glass fiber content of 50-70%, and the remainder being plastic.

[0023] More preferably, each axial reinforcing layer is formed by stacking prepreg films made of glass fibers. Even more preferably, the prepreg film is a continuous glass fiber prepreg film with a thickness of 0.2-0.5 mm and a glass fiber content of 50-70%; the remainder is plastic.

[0024] More preferably, the radial reinforcing layer is provided with at least two layers, the axial reinforcing layer is provided with at least two layers, the radial reinforcing layer and the axial reinforcing layer are alternately arranged, and a reinforcing core layer is formed by heating and welding.

[0025] More preferably, the surface layer is a flexible alloy layer, and even more preferably, the flexible alloy layer is an aluminum alloy layer.

[0026] Preferably, the surface layer and the reinforcing core layer are bonded and fixed together by an adhesive.

[0027] The adhesive is selected from any one of epoxy-nylon adhesive, epoxy-polysulfide adhesive, modified phenolic adhesive, phenolic-silicone adhesive, phenolic-acetal adhesive, polyurethane crosslinking agent, and polyester adhesive.

[0028] Preferably, step (3) is preceded by a step of applying a water-absorbing and swelling resin gel material to the location of the pipe to be repaired.

[0029] More preferably, the water-absorbing and swelling resin gel material comprises a dispersion resin and water-absorbing and swelling resin particles, wherein the water-absorbing and swelling resin particles are dispersed within the dispersion resin.

[0030] More preferably, the mass ratio of the dispersion resin to the water-absorbing and swelling resin particles is 10:0.2-1.

[0031] More preferably, the dispersion resin is polyacrylol or polyethylene glycol with a molecular weight greater than 100,000; the water-absorbing and swelling resin particles are water-absorbing and swelling resin materials formed by copolymerization of hydrophilic monomers, cationic monomers, and acrylamide.

[0032] The beneficial effects of this invention are as follows:

[0033] (1) The present invention provides a flexible composite pipe online repair method. First, the pipeline pressure is adjusted, and then water-absorbing and expanding resin gel material is applied to the pit to be repaired. The water-absorbing and expanding gel resin expands rapidly after absorbing water to block the damaged part of the pipe, thereby achieving online repair and preventing oil and gas from continuing to leak out. At the same time, it can also fill and repair the corrosion perforation of the pipe.

[0034] (2) The prepreg tape includes a reinforcing core layer and an alloy surface layer, which enhances the strength of the prepreg tape, making it suitable for high pressure transmission of gas and oil, ensuring pressure resistance, and enabling pipelines to be repaired without interrupting the pipe and draining the liquid, thereby increasing the repair speed and reducing the repair cost.

[0035] (3) Applied to online sealing of leaks in flexible continuous composite pipelines. No need to stop the flow or drain / vent, construction is fast, it can adapt to high-pressure flexible pipeline leak sealing operations, and has a wide range of applications. Detailed Implementation

[0036] To make the technical means, creative features, achieved objectives, and effects of this invention easier to understand, the invention is further illustrated below with specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention. Unless otherwise specified, the operating methods, equipment, and raw materials used in the following embodiments are all conventional operating methods.

[0037] In the following embodiments, the continuous glass fiber prepreg tape was purchased from Greed, with a thickness of 0.35 mm, a glass fiber content of 65%, and the remainder being plastic;

[0038] In the following embodiments, the continuous glass fiber prepreg film was purchased from Greed, with a thickness of 0.3 mm, a glass fiber content of 68%, and the remainder being plastic;

[0039] The adhesive used was Iron Anchor 204, purchased from Changzhou Jiama Baisheng Chemical Co., Ltd.

[0040] The adhesive used was epoxy resin adhesive 108T, purchased from Shenzhen Xiaodao Tiandi Technology Co., Ltd.

[0041] The aluminum alloy sheet was purchased from Dongguan Jinguang Metal Materials Co., Ltd.

[0042] In the following embodiments, the prepreg tape and the water-absorbing and swelling resin gel material are prepared according to the following steps:

[0043] Two layers of continuous glass fiber prepreg tape and two layers of continuous glass fiber film are alternately laid and then heated and fused to form a reinforcing core layer; then aluminum alloy sheet is bonded to the surface of the reinforcing core layer with adhesive to form prepreg tape;

[0044] Preparation of water-absorbing and swelling resin: The mass ratio of hydrophilic monomer acrylic acid, cationic monomer dimethyl diallyl ammonium chloride or dimethyl diallyl ammonium chloride, and acrylamide is 19:4.5:8; the amount of crosslinking agent added is 0.1%, and the crosslinking agent is N,N-methylenebisacrylamide. After the crosslinking agent forms a gel, it is stirred and cured, and the particles are shaped and cured to obtain water-absorbing and swelling resin particles. Then, the water-absorbing and swelling resin particles are put into a high molecular weight polyacrylol (molecular weight about 400,000) melt and stirred and mixed evenly to obtain water-absorbing and swelling resin gel material. The mass ratio of polyacrylol to water-absorbing and swelling resin particles is 10:0.8.

[0045] Example 1

[0046] A method for online repair of flexible composite pipes includes the following steps:

[0047] (1) Increase the gas flow rate into the pipeline to be repaired, and increase the pressure in the pipeline to be repaired (increase to...). ≥ The gas pressure is increased by 5MPa and then rapidly impacts the corroded area of ​​the pipeline to be repaired, causing the rust or unstable layer to fall off quickly and cleanly. The time for increasing the pressure does not exceed 1 minute.

[0048] (2) Reduce the pressure at the location of the pipeline to be repaired to the normal operating pressure to facilitate the laying of the prepreg tape;

[0049] (3) Heat the water-absorbing and swelling resin gel material (65°C) and apply it to the area of ​​the pipe to be repaired to fill the existing depressions or holes;

[0050] (4) After all the filling is completed, immediately after the water-absorbing and expanding resin gel material is applied, wrap the prepreg tape around the surface of the pipe to be repaired, and use adhesive to bond and wrap it to complete the repair.

[0051] Example 2

[0052] A method for online repair of flexible composite pipes includes the following steps:

[0053] (1) Increase the gas flow rate into the pipeline to be repaired and increase the pressure of the pipeline to be repaired (increase to ≥5MPa) so that the gas with increased pressure can quickly impact the corroded area of ​​the pipeline to be repaired, causing the rust layer or unstable layer to fall off quickly and cleanly. The time for increasing the pressure shall not exceed 1 minute.

[0054] (2) Reduce the pressure at the location of the pipeline to be repaired to facilitate the laying of prepreg tape.

[0055] (3) Wrap the prepreg tape around the surface of the pipe to be repaired, and use adhesive to bond and wrap it to complete the repair.

[0056] Result detection

[0057] Air tightness test method: Inject gas into the repaired pipe to a pressure of 1.5 MPa, maintain for 6 hours, and then measure the pressure.

[0058] Compressive strength test method: Gas is injected into the repaired pipe, and the pressure is gradually increased until the pipe breaks. The highest pressure before the pipe breaks is recorded.

[0059] Service life test method: Inject gas into the repaired pipe to a pressure of 3MPa and maintain it for 480 hours, then observe whether any damage occurs.

[0060] Table 1.

[0061] Serial Number Air tightness (6h) compressive strength Service life (3MPa, 480h) Example 1 1.5MPa (holding pressure) 12.5MPa No damage Example 2 1.5MPa (holding pressure) 11.7MPa No damage

[0062] The results show that the online repair method for flexible composite pipes of the present invention can achieve online repair, and the repaired pipe has good airtightness, high pressure resistance, and long service life.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of on-line repair of a flexible composite pipe, characterized by, Includes the following steps: (1) Increase the pressure of the pipeline to be repaired; (2) Reduce the pressure at the location of the pipeline to be repaired; (3) Wrap the outer surface of the pipe to be repaired with prepreg tape; The prepreg tape includes a reinforcing core layer and a surface layer. The reinforcing core layer includes a radial reinforcing layer and an axial reinforcing layer arranged sequentially from the inside to the outside. The surface layer is a flexible alloy layer. Each radial reinforcement layer is formed by obliquely winding glass fiber prepreg material; the glass fiber prepreg material is a continuous glass fiber prepreg tape with a thickness of 0.2-0.5 mm, a glass fiber content of 50-70%, and the remainder is plastic; Each axial reinforcing layer is formed by stacking prepregs made of glass fibers; the prepreg is a continuous glass fiber prepreg with a thickness of 0.2-0.5 mm and a glass fiber content of 50-70%; the remainder is plastic. The radial reinforcement layer is provided with at least two layers, the axial reinforcement layer is provided with at least two layers, the radial reinforcement layer and the axial reinforcement layer are alternately arranged, and a reinforcement core layer is formed by heating and welding, and the flexible alloy layer is an aluminum alloy layer; Before step (3), the following step is also included: applying a water-absorbing and swelling resin gel material to the location of the pipe to be repaired. The water-absorbing and swelling resin gel material includes a dispersion resin and water-absorbing and swelling resin particles, wherein the water-absorbing and swelling resin particles are dispersed inside the dispersion resin, and the mass ratio of the dispersion resin to the water-absorbing and swelling resin particles is 10:0.2-1; the dispersion resin is polyacrylol or polyethylene glycol with a molecular weight greater than 100,000; the water-absorbing and swelling resin particles are a water-absorbing and swelling resin material formed by copolymerization of hydrophilic monomers, cationic monomers, and acrylamide.

2. The online repair method for flexible composite pipes according to claim 1, characterized in that, In step (1), the pressure of the pipeline to be repaired is increased by increasing the amount of gas or liquid introduced into the pipeline. The introduced gas or liquid enters the pipeline along the tangent of the pipeline to be repaired.

3. The online repair method for flexible composite pipes according to claim 1, characterized in that, In step (1), the pressure increase time shall not exceed 1 minute.

4. The online repair method for flexible composite pipes according to claim 1, characterized in that, In step (3), the prepreg tape is bonded to the pipe to be repaired using an adhesive.

5. The online repair method for flexible composite pipes according to claim 1, characterized in that, The surface layer and the reinforcing core layer are bonded and fixed together by adhesive.