A composite oil well pipe and a method of manufacturing the same

Abstract

The application provides a composite oil well pipe and a manufacturing method thereof, and relates to the technical field of oil and gas exploitation equipment. The composite oil well pipe comprises, from inside to outside, an inner lining layer, an intermediate base layer and an outer coating layer. The intermediate base layer is made of alloy steel. The inner lining layer and the outer coating layer are made of corrosion-resistant alloy. The inner lining layer and the intermediate base layer are metallurgically combined, and the outer coating layer and the intermediate base layer are also metallurgically combined. The manufacturing method is used for manufacturing the composite oil well pipe, and comprises the following steps: sand blasting treatment and hot air drying are performed on the surfaces of the inner lining layer and the intermediate base layer; the inner lining layer is sleeved into the intermediate base layer, heated and hot drawn to make the inner lining layer and the intermediate base layer metallurgically combined; the outer coating layer is laser fused on the outer wall of the double-layer pipe material after the combination, so that the outer coating layer and the intermediate base layer are metallurgically combined; cutting is performed according to the target size; and double normalizing and quenching and tempering heat treatment are performed on the pipe material after cutting and shaping. The application improves the corrosion resistance of the inner and outer walls of the pipe and reduces the manufacturing cost under the premise of ensuring the strength of the oil well pipe.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction equipment technology, and in particular to a composite oil well pipe and its manufacturing method. Background Technology

[0002] During the oil and gas extraction process, as oil and gas field development gradually enters the middle and late stages, the wellbore service environment becomes increasingly harsh. Under the combined effects of high temperature, high pressure, and highly corrosive media, the inner wall of the oil well pipe suffers severe corrosion due to the transported medium.

[0003] Currently, oil well tubing mainly adopts the following two technical solutions: One type is the bimetallic composite pipe, which uses carbon steel as the outer matrix and a corrosion-resistant alloy layer on the inner side. By organically combining the high strength of the outer carbon steel layer and the corrosion resistance of the inner corrosion-resistant alloy layer, the corrosion resistance of the pipeline is improved and the cost is reduced, which has attracted widespread attention in the field of oil and gas well development. However, this type of bimetallic composite pipe only has the ability to protect against the medium inside the pipe and cannot resist the corrosion of the outer wall by the liquid and gaseous media in the wellbore annulus. In the pressurized and highly corrosive environment of the annulus, the outer wall is prone to corrosion failure, resulting in short service life and high safety risks.

[0004] Another type is oil wells made of corrosion-resistant materials. These typically use pure corrosion-resistant materials, such as chromium-based and nickel-based pure materials, or pure corrosion-resistant alloy oil well pipes made of chromium-based and nickel-based materials. Both the inner and outer walls of these pipes have excellent corrosion resistance. However, the raw materials are expensive, resulting in extremely high costs and significantly increasing investment in oil and gas field development, making it difficult to promote and apply them on a large scale.

[0005] In addition, most existing composite pipes are mechanically composited, resulting in low interfacial bonding strength and problems such as delamination and detachment, which cannot meet the requirements for long-term downhole service.

[0006] Therefore, there is an urgent need for a composite oil well pipe and its manufacturing method to solve the above-mentioned technical problems. Summary of the Invention

[0007] The purpose of this invention is to provide a composite oil well pipe and its manufacturing method, to solve the problems of existing technologies, such as bimetallic composite pipes which only protect against the internal medium and cannot resist corrosion of the outer wall by liquid and gaseous media in the wellbore annulus, easily leading to outer wall corrosion failure under annular pressure and high corrosion environment, resulting in short service life and high safety risks; chromium-based and nickel-based pure corrosion-resistant alloy oil well pipes, which have excellent corrosion resistance on both the inner and outer walls, but the raw materials are expensive, resulting in extremely high costs and significantly increasing investment in oil and gas field development, making large-scale application difficult; and existing composite pipes mostly use mechanical bonding, resulting in low interfacial bonding strength, easy delamination and detachment, and failing to meet the technical problems of long-term downhole service requirements. The various technical effects of the preferred technical solutions provided by this invention are detailed below.

[0008] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a composite oil well pipe, comprising an inner lining layer, an intermediate base layer, and an outer coating layer arranged sequentially from the inside to the outside, wherein: The intermediate base layer is made of alloy steel. Both the inner lining and the outer coating are made of corrosion-resistant alloy material; The inner lining layer and the intermediate base layer, as well as the outer cladding layer and the intermediate base layer, are all bonded together using metallurgical bonding.

[0009] Furthermore, the thickness of the inner lining layer is 2mm to 3mm, and the corrosion-resistant alloy is duplex stainless steel or nickel-based alloy.

[0010] Furthermore, the duplex stainless steel includes 2205 and 2507; the nickel-based alloy includes 825, 625, and G3.

[0011] Furthermore, the thickness of the intermediate base layer is 5mm to 8mm, and the alloy steel includes 27CrMo4 and 30CrMoA.

[0012] Furthermore, the thickness of the outer coating is 1.5mm to 2.5mm, and the corrosion-resistant alloy is austenitic stainless steel or duplex stainless steel.

[0013] Furthermore, the austenitic stainless steel includes 316 and 316L; the duplex stainless steel includes 2205 and 2507.

[0014] Secondly, the present invention provides a method for manufacturing a composite oil well pipe, comprising the following steps: S1: The surfaces of the inner lining and intermediate base layer are sandblasted and dried with hot air to make the inner and outer pipe walls dry and clean. S2: The inner lining is inserted into the intermediate base layer, and after being heated to 850℃~1150℃, it is hot-drawn to make the inner lining and the intermediate base layer metallurgically bonded. S3: Laser cladding is applied to the outer wall of the composite double-layer pipe to form an outer coating layer, thus metallurgically bonding the outer coating layer with the intermediate base layer. S4: Remove the head and tail of the composite three-layer pipe and cut it to the target size; S5: Perform double normalizing and tempering heat treatment on the cut and shaped pipes.

[0015] Further, in step S5, the double normalizing includes: First normalizing: Heat to 860℃~890℃, hold for 45min~60min, and air cool to room temperature; Second normalizing: Continue heating to 910℃~920℃, hold for 30min~40min, and then air cool to room temperature.

[0016] Further, in step S5, the tempering includes: heating to 860℃~890℃, holding for 45min~70min, water quenching, high-temperature tempering at 520℃~570℃, holding for 49min~70min, and air cooling to room temperature.

[0017] Furthermore, in step S2, the heating is eddy current heating, the hot drawing is necking hot drawing, and the inner mold and the inner liner tube are interference fit during hot drawing.

[0018] The composite oil well pipe provided by this invention has a multi-layer composite structure consisting of an inner liner, an intermediate base layer, and an outer coating layer, arranged from the inside out. The inner liner is made of corrosion-resistant alloy material, the intermediate base layer is made of alloy steel material, and the outer coating layer is also made of corrosion-resistant alloy material. Both the inner liner and the outer coating layer are metallurgically connected to the intermediate base layer to form a multi-layer metallurgical composite, which can effectively avoid the problem of detachment or failure. While ensuring the strength of the oil well pipe, it improves the corrosion resistance of both the inner and outer walls of the pipe. At the same time, the manufacturing cost is much lower than that of chromium-based and nickel-based pure material oil pipes.

[0019] The manufacturing method of the composite oil well pipe provided by this invention adopts a necking hot drawing process for the metallurgical composite of the inner lining layer and the intermediate base layer, and a laser coating process for the metallurgical composite of the outer layer and the intermediate base layer. After normalizing and modulating heat treatment, a stable multi-layer composite structure is formed. The manufactured multi-layer composite oil well pipe not only improves the corrosion resistance of the inner wall of the oil well pipe, but also ensures the corrosion resistance of the outer wall of the oil well pipe. Moreover, its manufacturing cost is much lower than that of chromium-based or nickel-based pure material oil well pipes, and it can replace chromium-based or nickel-based pure material oil well pipes in highly corrosive environments. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the composite oil well pipe of the present invention; Figure 2 This is a schematic diagram of the manufacturing process of the composite oil well pipe of the present invention.

[0022] In the diagram: 1. Inner lining layer; 2. Intermediate base layer; 3. Outer cladding layer; 4. Eddy current heating device; 5. Outer mold; 6. Inner mold; 7. Laser cladding device. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0024] In the description of this invention, it should be understood that the terms "center," "side," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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 invention.

[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Figure 1 This is a structural schematic diagram of this embodiment, as shown below. Figure 1 As shown, this embodiment provides a composite oil well pipe, comprising an inner liner 1, an intermediate base layer 2, and an outer coating layer 3 arranged sequentially from the inside out. The intermediate base layer 2 is made of alloy steel; both the inner liner 1 and the outer coating layer 3 are made of corrosion-resistant alloy material. Through this three-layer composite structure, the corrosion-resistant alloy inner liner 1 and outer coating layer 3 achieve bidirectional corrosion resistance both inside and outside the pipe, while the alloy steel intermediate base layer 2 ensures structural strength. Furthermore, the inner liner 1 and intermediate base layer 2, as well as the outer coating layer 3 and intermediate base layer 2, are metallurgically bonded, forming permanent molecular connections. This ensures a strong interface bond, eliminates the risk of delamination and detachment, and allows for long-term stable service even under highly corrosive oil and gas well conditions.

[0027] In this embodiment, the thickness of the inner lining layer 1 is 2mm to 3mm. While ensuring the corrosion resistance of the inner wall, the impact of the inner lining layer 1 on the pipe diameter is minimized, and the amount of corrosion-resistant alloy used is controlled to reduce costs. The corrosion-resistant alloy is selected from duplex stainless steel or nickel-based alloys. For example, using 2205 or 2507 duplex stainless steel or 825, 625, or G3 nickel-based alloys can provide excellent corrosion resistance and mechanical stability for extreme corrosive environments, thus meeting the service requirements of high-temperature and high-pressure oil and gas wells.

[0028] In this embodiment, the thickness of the intermediate base layer is 5mm to 8mm to ensure the overall strength, rigidity, and resistance to external pressure of the oil well pipe. Specifically, alloy steels such as 27CrMo4 and 30CrMoA are used, which combine high strength, good toughness, and weldability to meet the load-bearing requirements of the oil well pipe structure.

[0029] In this embodiment, the thickness of the outer coating is 1.5mm to 2.5mm, effectively resisting the erosion of the outer wall by the corrosive medium in the wellbore annulus. The corrosion-resistant alloy is austenitic stainless steel or duplex stainless steel, achieving long-term corrosion protection of the outer wall and solving the problem of easy corrosion failure of the outer wall in traditional composite pipes. Specifically, austenitic stainless steel includes 316 and 316L; duplex stainless steel includes 2205 and 2507, balancing corrosion resistance and economy, ensuring strong corrosion resistance and moderate cost of the outer coating, suitable for large-scale application.

[0030] Figure 2 This is a schematic diagram of the composite oil well pipe manufacturing process, such as... Figure 2 As shown, this embodiment provides a method for manufacturing a composite oil well pipe, which includes the following steps: S1: The surfaces of the inner lining layer 1 and the intermediate base layer 2 are sandblasted and dried with hot air to make the inner and outer pipe walls dry and clean.

[0031] Specifically, in this embodiment, sandblasting technology is used in the surface treatment of the inner lining layer 1 and the intermediate base layer 2. Quartz sand is used as the abrasive. A rotating nozzle is used on the inner surface, and hot air is used for drying to make the inner and outer pipe walls completely dry and clean.

[0032] S2: The inner lining layer 1 is fitted into the intermediate base layer 2, and after heating to 850℃~1150℃, it is hot-drawn to achieve a metallurgical bond between the inner lining layer and the intermediate base layer. The heating is eddy current heating, and the hot drawing is necking hot drawing. During hot drawing, the inner mold and the inner lining tube are interference-fitted. Eddy current heating ensures rapid and uniform temperature rise, and the necking hot drawing and interference fit ensure a tight fit between the inner lining layer 1 and the intermediate base layer 2, resulting in a strong metallurgical bond and higher interfacial bonding strength, further guaranteeing the long-term reliability of the composite pipe.

[0033] During the production process, the metallurgical composite process of the inner lining layer 1 and the intermediate base layer 2 specifically includes: First, after placing the intermediate base layer 2 horizontally, push the inner lining layer 1 into the inner hole of the intermediate base layer 2. If necessary, it can be done by pulling and pushing.

[0034] Then, the inner lining layer 1 and the intermediate base layer 2, which are nested together, are heated. The heating can be done using an eddy current heating device 4, with a heating temperature of 850-1150℃. Then, a suitable drawing machine is selected for hot drawing to ensure a stable drawing speed. A suitable outer mold 5 is selected to ensure accurate outer diameter dimensions. A suitable inner mold 6 is selected to maintain an interference fit with the inner lining tube, ensuring that the outer wall of the inner lining layer 1 and the inner wall of the intermediate base layer 2 are fully fused to form intermolecular bonds, making the thickness of the inner lining layer 1 2-3mm, thereby improving the corrosion resistance to the fluid inside the tube.

[0035] S3: Laser cladding is applied to the outer wall of the composite double-layer pipe to form an outer layer 3 that is metallurgically bonded to the intermediate base layer 2.

[0036] Specifically, an outer layer 3 is applied to the inner and outer double-layer tube after the drawing process. The outer layer 3 is applied using a laser automatic cladding device 7. Cladding is a forming technology of metal in the liquid phase, which is a permanent connection between molecules, forming an outer layer 3 with a thickness of 1.5 to 2.5 mm, thereby improving the corrosion resistance to corrosive media outside the tube.

[0037] S4: Remove the head and tail of the composite three-layer pipe and cut it to the target size.

[0038] S5: Perform double normalizing and tempering heat treatment on the cut and shaped pipes.

[0039] The double normalizing process includes: First normalizing: heating to 860℃~890℃, holding for 45min~60min, and air-cooling to room temperature; Second normalizing: further heating to 910℃~920℃, holding for 30min~40min, and air-cooling to room temperature. This double normalizing treatment refines the grains, homogenizes the microstructure, eliminates internal stress, and improves the toughness and structural stability of the composite pipe, preventing deformation and cracking during use.

[0040] The tempering process includes: heating to 860℃~890℃, holding for 45min~70min, water quenching, high-temperature tempering at 520℃~570℃, holding for 49min~70min, and air cooling to room temperature. Through quenching and high-temperature tempering, the alloy steel of the intermediate base layer 2 achieves optimal strength and toughness matching, while protecting the corrosion-resistant alloy layer from degradation, thus improving the overall load-bearing capacity and service life of the oil well pipe.

[0041] The following describes the manufacturing method of the composite oil well pipe, using a 3-1 / 2 inch 30CrMoA alloy steel pipe as the intermediate base layer 2, with dimensions of φ88.9mm × 5.45mm. A 2mm thick nickel-based alloy 625 is used as the inner lining layer 1, and a 1mm thick austenitic stainless steel 316L is used as the outer coating layer 3. Liquid phase fusion is achieved through a combination of hot and pressure, resulting in intermolecular bonding. The outer coating layer 3 is then laser-fused to achieve liquid phase fusion and intermolecular bonding. The specific steps are as follows: S1: Surface treatment of the inner lining layer 1 and the intermediate base layer 2, specifically including: S11: Surface treatment adopts sandblasting technology, using quartz sand as abrasive, with a blasting pressure of 0.5MPa~0.8MPa and a blasting speed of 70m / s~90m / s; S12: High-pressure water jet cleaning, using 100MPa~250MPa high-pressure water to clean the surface; rotating nozzles can be used for the inner surface. S13: Drying, using hot air drying, the inner and outer pipe walls are completely dry and clean.

[0042] S2: Metallurgical composite of inner lining layer 1 and intermediate base layer 2, specifically including: S21: After placing the intermediate base layer 2 horizontally, push the inner lining layer 1 into the inner hole of the intermediate base layer 2. If necessary, the pulling and pushing methods can be used. S22: Heat the inner lining layer 1 and the intermediate base layer 2 that are nested together. The heating can be done by eddy current heating, and the heating temperature is 950℃~1100℃. S23: Place one end of the heated inner lining layer 1 and the intermediate base layer 2 into the necking machine for necking operation; S24: Select a suitable drawing machine and a suitable outer die to ensure accurate outer diameter dimensions. Select a suitable inner die to ensure an interference fit with the inner liner tube. The interference amount is 200μm to 350μm to ensure that the outer wall of the inner liner layer and the inner wall of the intermediate base layer are fully fused together to form intermolecular connections. S25: The steel pipe is drawn according to the hot-drawn steel pipe process, and the drawing speed is 5m / min~10m / min.

[0043] S3: Outer layer 3 setting. Specifically, an outer layer is set for the inner and outer double-layer tube after the drawing process. The outer layer is automatically laser-bonded. The laser bonding can be done using single-channel or dual-channel automated equipment. The weld layer thickness is 0.3mm~0.4mm and the bonding speed is 5m / min~10m / min.

[0044] S4: Size determination, specifically including removing the head and tail of the three-layer pipe and cutting it to the specified size.

[0045] S5: Heat treatment is performed on pipelines with fixed dimensions. Heat treatment includes normalizing and quenching and tempering.

[0046] The double normalizing process involves heating to 860℃-890℃, holding for 45-60 minutes, and then air-cooling to room temperature; followed by heating to 910℃-920℃, holding for 30-40 minutes, and then air-cooling to room temperature.

[0047] The quenching and tempering process is as follows: heat to 860℃-890℃, hold for 45min-70min, water quench; high temperature tempering temperature 520℃-570℃, hold for 49min-70min, air cool to room temperature.

[0048] The manufacturing method of this composite oil well pipe adopts a necking hot drawing process for the metallurgical composite of the inner lining layer 1 and the intermediate base layer 2, and adopts a laser coating process for the metallurgical composite of the outer layer 3 and the intermediate base layer 2. After normalizing and modulating heat treatment, a stable multi-layer composite structure is formed, and the above-mentioned multi-layer composite structure oil well pipe is manufactured. While improving the corrosion resistance of the inner wall, it also ensures the corrosion resistance of the outer wall. Its manufacturing cost is far lower than that of chromium-based and nickel-based pure material oil pipes.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A composite oil well pipe, characterized in that, It includes, from the inside out, an inner lining layer, an intermediate base layer, and an outer cladding layer, wherein: The intermediate base layer is made of alloy steel. Both the inner lining and the outer coating are made of corrosion-resistant alloy material; The inner lining layer and the intermediate base layer, as well as the outer cladding layer and the intermediate base layer, are all bonded together using metallurgical bonding.

2. The composite oil well pipe according to claim 1, characterized in that: The thickness of the inner lining layer is 2mm to 3mm, and the corrosion-resistant alloy is duplex stainless steel or nickel-based alloy.

3. A composite oil well pipe according to claim 2, characterized in that: The duplex stainless steels include 2205 and 2507; the nickel-based alloys include 825, 625, and G3.

4. The composite oil well pipe according to claim 1, characterized in that: The thickness of the intermediate base layer is 5mm to 8mm, and the alloy steel includes 27CrMo4 and 30CrMoA.

5. A composite oil well pipe according to claim 1, characterized in that: The thickness of the outer coating is 1.5mm to 2.5mm, and the corrosion-resistant alloy is austenitic stainless steel or duplex stainless steel.

6. A composite oil well pipe according to claim 5, characterized in that: The austenitic stainless steel includes 316 and 316L; the duplex stainless steel includes 2205 and 2507.

7. A method for manufacturing a composite oil well pipe, used to manufacture the composite oil well pipe according to any one of claims 1-6, characterized in that, Includes the following steps: S1: The surfaces of the inner lining and intermediate base layer are sandblasted and dried with hot air to make the inner and outer pipe walls dry and clean. S2: The inner lining is inserted into the intermediate base layer, and after being heated to 850℃~1150℃, it is hot-drawn to make the inner lining and the intermediate base layer metallurgically bonded. S3: Laser cladding is applied to the outer wall of the composite double-layer pipe to form an outer coating layer, thus metallurgically bonding the outer coating layer with the intermediate base layer. S4: Remove the head and tail of the composite three-layer pipe and cut it to the target size; S5: Perform double normalizing and tempering heat treatment on the cut and shaped pipes.

8. The method for manufacturing the composite oil well pipe according to claim 7, characterized in that, In step S5, the double normalizing includes: First normalizing: Heat to 860℃~890℃, hold for 45min~60min, and air cool to room temperature; Second normalizing: Continue heating to 910℃~920℃, hold for 30min~40min, and then air cool to room temperature.

9. The method for manufacturing the composite oil well pipe according to claim 7, characterized in that, In step S5, the tempering includes: heating to 860℃~890℃, holding for 45min~70min, water quenching, high-temperature tempering at 520℃~570℃, holding for 49min~70min, and air cooling to room temperature.

10. The method for manufacturing the composite oil well pipe according to claim 7, characterized in that, In step S2, the heating is eddy current heating, the hot drawing is necking hot drawing, and the inner mold and the inner liner tube are interference fit during hot drawing.

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