Integral metallurgical composite bimetallic oil pipe and its manufacturing process

Abstract

This invention relates to the field of oil casing for energy exploration and development, and provides an integral metallurgical composite bimetallic tubing and its manufacturing process. The process includes: S1: performing a first external upsetting on the first end of the tubing, after which the outer surface dimensions of the tubing end meet the requirements of the outer diameter of the internal threaded joint, and the inner surface of the tubing end is conical; S2: performing a second upsetting on the internal threaded joint section of the first end, after which the outer surface dimensions of the first end of the tubing remain unchanged, the inner surface is conical, and the thickness of the corrosion-resistant alloy layer on the inner surface increases linearly from the end face along the axial direction inward; S3: performing overall heat treatment; S4: machining the internal thread on the first end of the tubing; S5: machining the external thread on the second end of the tubing. This invention forms a corrosion-resistant alloy torque shoulder at the thread end of the internal threaded joint, solving the problem of corrosion resistance treatment at the internal thread end of the corrosion-resistant alloy tubing thread; it eliminates the need to use corrosion-resistant alloy welding to form a corrosion-resistant alloy layer at the internal thread end, effectively reducing tubing production costs and improving production efficiency.

Description

Technical Field

[0001] This invention relates to the field of oil casing for energy exploration and development, and particularly to an integral metallurgical composite bimetallic tubing and its manufacturing process. Background Technology

[0002] Bimetallic composite pipes, due to their excellent corrosion resistance of the inner layer, are increasingly used in the exploration and development of energy resources such as oil, natural gas, and coalbed methane. For example, they are used to manufacture oil casing to stabilize the wellbore and form oil and gas channels. However, the corrosion resistance between the pipe body and the coupling at the threaded connection of bimetallic tubing fittings is a significant factor limiting their application. This includes potential difference corrosion between the surface substrate and the inner corrosion-resistant alloy layer of the bimetallic tubing, and potential difference corrosion between the tubing body and the coupling material. Currently, the common method for addressing the threaded connection of bimetallic composite pipes is to weld the same corrosion-resistant alloy material onto the pipe end and the coupling surface, ensuring that both the pipe body and the coupling connection use the same corrosion-resistant alloy material. This increases the cost of the threaded connection, adds manufacturing steps, and reduces production efficiency.

[0003] Therefore, it is necessary to study an integral metallurgical composite bimetallic tubing manufacturing process to address the shortcomings of existing technologies and to solve or mitigate one or more of the aforementioned problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an integral metallurgical composite bimetallic oil pipe and its manufacturing process, which solves the problems of high cost and low production efficiency of welding corrosion-resistant alloy inside the bimetallic composite threaded connection coupling in the prior art.

[0005] The present invention adopts the following technical solution:

[0006] On one hand, the present invention provides a manufacturing process for an integral metallurgical composite bimetallic oil pipe, wherein the outer layer of the bimetallic oil pipe is metal and the inner layer is a corrosion-resistant alloy, and the process includes:

[0007] S1. The first end of the initial double-layer metal tube is subjected to external thickening and upsetting. After upsetting, the outer surface dimension of the tube end meets the outer diameter requirements of the internal threaded joint, and the inner surface of the tube end is conical.

[0008] S2. The internal threaded joint section at the first end is upset a second time. After upset, the outer surface dimension of the first end of the pipe remains unchanged, the inner surface is conical, and the thickness of the corrosion-resistant alloy layer on the inner surface increases linearly from the end face along the axial direction inward.

[0009] S3. Perform overall heat treatment on the tube body after S1 and S2 treatment;

[0010] S4. Perform internal thread machining on the first end of the pipe body to form a corrosion-resistant alloy internal thread torque shoulder on the innermost side of the internal thread joint section.

[0011] S5. Perform external thread machining on the second end of the tube body, wherein the external thread matches the internal thread formed in step S4.

[0012] In addition to any of the possible implementations described above, a further implementation is provided in which the outer layer of the bimetallic tubing is made of carbon steel, and the thickness of the inner corrosion-resistant alloy layer is greater than or equal to 1.5 mm. Experiments show that if the thickness of the corrosion-resistant alloy is less than 1.5 mm, the protective function may be inadequate. This thickness limitation can better ensure the integrity of the corrosion-resistant alloy at the threaded connection.

[0013] In addition to any of the possible implementations described above, another implementation is provided in which, after the upsetting process in step S1, the outer surface of the first upsetting section of the tube body is composed of a first conical section and a cylindrical section, and the outer diameter of the cylindrical section is not less than 1.1 times the outer diameter of the tube body.

[0014] In addition to any of the possible implementations described above, another implementation is provided in which the outer diameter of the cylindrical segment is 1.2 times the outer diameter of the tube.

[0015] In addition to any of the possible implementations described above, another implementation is provided in which, after the upsetting process in step S1, the inner surface of the upsetting section at the first end of the tube body forms a second conical section with a taper of less than 1:16.

[0016] In addition to any of the possible implementations described above, another implementation is provided in which the taper of the second conical segment is 1:20.

[0017] In addition to any of the possible implementations described above, a further implementation is provided in which the secondary upsetting is performed by die forging upsetting, and the corrosion-resistant alloy layer flows and accumulates from the end to the inside.

[0018] In addition to any of the possible implementations described above, another implementation is provided in which, after the second upsetting process in step S2, a third conical section is formed on the inner surface of the first upsetting section of the tube body, and the thickness of the corrosion-resistant alloy layer at the small end of the inner diameter of the third conical section is not less than 3 mm.

[0019] In addition to any of the possible implementations described above, a further implementation is provided in which, in step S4, after the internal thread is machined at the first end of the pipe body, the torque shoulder surface at the end of the internal thread is made of a corrosion-resistant alloy, and the thickness of the torque shoulder surface is greater than 2mm. Experiments show that when the thickness is less than 2mm, the torque shoulder is easily deformed under compression, causing damage at this point.

[0020] In addition to any of the possible implementations described above, another implementation is provided in which the overall heat treatment in step S3 is a quenching and tempering treatment.

[0021] In addition to any of the possible implementations described above, another implementation is provided, in which the quenching and tempering treatment specifically comprises: quenching + tempering at 970°C for 30 minutes, quenching, tempering at 600°C for 120 minutes, and then air cooling.

[0022] On the other hand, the present invention also provides an integral metallurgical composite bimetallic oil pipe, which is obtained by the above-described integral metallurgical composite bimetallic oil pipe manufacturing process.

[0023] When the two integral metallurgical composite bimetallic oil pipes of the present invention are connected, since the torque shoulder is made of corrosion-resistant alloy and the inner end face of the external thread on the other end is also made of corrosion-resistant alloy, the entire inner surface of the pipe is made of corrosion-resistant alloy after connection and will not be corroded.

[0024] The beneficial effects of this invention are as follows: This invention provides a manufacturing process for an integral metallurgical composite bimetallic tubing. This process uses a special secondary upsetting process to integrally upset the internal thread end of the composite tubing, causing the corrosion-resistant alloy in the inner layer of the composite tubing to accumulate and flow from the end to the inside. Thus, after the internal thread is machined following upsetting, a corrosion-resistant alloy torque shoulder is formed at the thread end, solving the problem of corrosion resistance treatment at the internal thread end of the corrosion-resistant alloy tubing. Compared with the conventional method of welding corrosion-resistant alloy onto the inner surface of the coupling during threaded connection of current bimetallic composite tubing, this invention does not require corrosion-resistant alloy welding to form a corrosion-resistant alloy layer at the internal thread end, thereby effectively reducing the production cost of the tubing and improving production efficiency. Attached Figure Description

[0025] Figure 1 The diagram shown is a schematic diagram of the manufacturing process of an integral metallurgical composite bimetallic oil pipe according to an embodiment of the present invention.

[0026] Among them: 1. Double-layer metal pipe body; 1-1. Outer layer carbon steel; 1-2. Inner layer corrosion-resistant alloy; 1-3. Cylindrical section of internal threaded joint; 1-4. Outer conical section (first conical surface section) of internal threaded joint; 1-5. Second conical surface section inside internal threaded joint after first upsetting; 1-6. Third conical surface section inside internal threaded joint after second upsetting; 1-7. Internal thread; 1-8. Torque shoulder of internal thread; 1-9. External thread. Detailed Implementation

[0027] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, but can be combined with each other to achieve better technical effects.

[0028] like Figure 1As shown in the embodiment of the present invention, a manufacturing process for an integral metallurgical composite bimetallic oil pipe is provided. The outer layer of the bimetallic oil pipe is metal, and the inner layer is a corrosion-resistant alloy. The process includes:

[0029] S1. The first end of the initial double-layer metal pipe body 1 is subjected to external thickening and upsetting. After upsetting, the outer surface dimension of the pipe end meets the outer diameter requirements of the internal threaded joint, and the inner surface of the pipe end is conical.

[0030] S2. The internal threaded joint section at the first end is upset a second time. After upset, the outer surface dimension of the first end of the pipe remains unchanged, the inner surface is conical, and the thickness of the corrosion-resistant alloy layer on the inner surface increases linearly from the end face along the axial direction inward.

[0031] S3. Perform overall heat treatment on the tube body after S1 and S2 treatment;

[0032] S4. Perform internal thread machining on the first end of the pipe body to form a corrosion-resistant alloy internal thread torque shoulder 1-8 on the innermost side of the internal thread joint section.

[0033] S5. The second end of the tube body is machined with external threads 1-9, which match the internal threads 1-7 formed in step S4.

[0034] In one specific embodiment, the outer layer of the bimetallic tubing is made of carbon steel 1-2, and the thickness of the inner corrosion-resistant alloy 1-3 is greater than or equal to 1.5 mm.

[0035] In one specific embodiment, after the upsetting process in step S1, the outer surface of the first upsetting section of the tube body is composed of a first conical section 1-4 and a cylindrical section 1-3, and the outer diameter of the cylindrical section 1-3 is not less than 1.1 times the outer diameter of the tube body.

[0036] In a preferred embodiment, the outer diameter of the cylindrical segments 1-3 is 1.2 times the outer diameter of the tube.

[0037] In one specific embodiment, after the upsetting process in step S1, the inner surface of the upsetting section at the first end of the tube body forms a second conical section 1-5 with a taper of less than 1:16.

[0038] In a preferred embodiment, the taper of the second conical segment 1-5 is 1:20.

[0039] In one specific embodiment, the secondary upsetting is performed by die forging upsetting, during which the corrosion-resistant alloy layer flows and accumulates from the end inward.

[0040] In one specific embodiment, after the second upsetting process in step S2, a third conical section 1-6 is formed on the inner surface of the first upsetting section of the tube body, and the thickness of the corrosion-resistant alloy layer at the small end of the inner diameter of the third conical section 1-6 is not less than 3mm.

[0041] In one specific embodiment, in step S4, after the internal thread is machined at the first end of the pipe body, the torque shoulder 1-8 surface at the end of the internal thread 1-7 is made of corrosion-resistant alloy, and the thickness of the torque shoulder 1-8 surface is greater than 2mm.

[0042] In one specific embodiment, in step S3, the overall heat treatment is a quenching and tempering treatment.

[0043] In one specific embodiment, for a composite pipe with an outer layer of carbon steel and an inner layer of corrosion-resistant alloy, the heat treatment specifically includes: quenching + tempering at 970°C for 30 minutes, followed by quenching, tempering at 600°C for 120 minutes, and then air cooling.

[0044] On the other hand, the present invention also provides an integral metallurgical composite bimetallic oil pipe, which is obtained by the above-described integral metallurgical composite bimetallic oil pipe manufacturing process.

[0045] This invention utilizes a special secondary upsetting process to integrally upset the internal thread end of the composite tubing. This allows the corrosion-resistant alloy in the inner layer of the composite tubing to accumulate and flow from the outside inwards from the end. After the internal thread is machined in the upsetting section, a corrosion-resistant alloy torque shoulder is formed at the thread end, solving the corrosion resistance problem of the internal thread end of the corrosion-resistant alloy tubing. Compared to the conventional method of welding corrosion-resistant alloy onto the inner surface of the coupling during threaded connections in bimetallic composite tubing, this invention eliminates the need for welding corrosion-resistant alloy to form a corrosion-resistant alloy layer at the internal thread end, thereby effectively reducing tubing production costs and improving production efficiency.

[0046] While embodiments of the present invention have been provided herein, those skilled in the art should understand that modifications can be made to the embodiments without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.

Claims

1. A process for the production of a monolithic metallurgical clad bimetallic oil country tubular goods having an outer layer of a metal and an inner layer of a corrosion resistant alloy, characterized by, The process comprises: S1, once-upset of the first end of the initial double-layer metal pipe, the outer surface size of the upset end meets the outer diameter requirement of the internal thread joint, and the inner surface of the end is conical; S2, twice-upset of the internal thread joint section of the first end, the outer surface size of the first end of the pipe body remains unchanged after the upset, the inner surface is a conical surface, and the thickness of the corrosion-resistant alloy layer of the inner surface linearly increases from the end surface along the axial direction; S3, overall heat treatment of the pipe body after S1 and S2; S4, internal thread processing of the first end of the pipe body, forming a corrosion-resistant alloy internal thread torque shoulder at the innermost side of the internal thread joint section; S5, external thread processing of the second end of the pipe body, the external thread matches the internal thread formed in step S4.

2. The process for making a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 1 wherein, The outer layer of the double-metal oil pipe is carbon steel, and the thickness of the corrosion-resistant alloy layer of the inner layer is greater than or equal to 1.5 mm.

3. The process for making a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 1 wherein, After the once-upset treatment in step S1, the outer surface of the upset section of the first end of the pipe body is composed of a first conical section and a cylindrical section, and the outer diameter of the cylindrical section is not less than 1.1 times the outer diameter of the pipe body.

4. The process for producing a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 3 wherein, The outer diameter of the cylindrical section is 1.2 times the outer diameter of the pipe body.

5. The process for making a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 3 wherein, After the once-upset treatment in step S1, the inner surface of the upset section of the first end of the pipe body forms a second conical section, and the taper is less than 1:

16.

6. The process for making a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 5 wherein, The taper of the second conical section is 1:

20.

7. The process for making a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 1 wherein, After the twice-upset treatment in step S2, the inner surface of the upset section of the first end of the pipe body forms a third conical section, and the thickness of the corrosion-resistant alloy layer at the small end of the inner diameter of the third conical section is not less than 3 mm.

8. The process for making a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 1 wherein, In step S4, after the internal thread of the first end of the pipe body is processed, the torque shoulder surface at the end of the internal thread is corrosion-resistant alloy, and the thickness of the torque shoulder surface is greater than 2 mm.

9. The process for making a monolithic metallurgically bonded bimetallic oil country tubular goods of claim 1 wherein, In step S3, the overall heat treatment is quenching and tempering treatment.

10. A monolithic metallurgically bonded bimetallic oil country tubular goods characterized by, The integral metallurgical composite double-metal oil pipe is obtained by the preparation process of the integral metallurgical composite double-metal oil pipe according to any one of claims 1-9.

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