A composite bimetallic drill pipe and a method of making the same

Abstract

This invention provides a composite bimetallic drill pipe and its preparation method. A first aspect of this invention provides a method for preparing a composite bimetallic drill pipe, the method comprising the following steps: preparing a bimetallic drill pipe joint; preparing a bimetallic drill pipe body; friction welding the end of a first region of the drill pipe joint to the end of a second region of the drill pipe body; after welding, applying a third corrosion-resistant alloy layer to the inner wall of the weld area between the drill pipe joint and the drill pipe body, and fusing the third corrosion-resistant alloy layer with the first and second corrosion-resistant alloy layers. According to the preparation method provided by this invention, a complete corrosion-resistant alloy layer is formed on the entire inner wall of the drill pipe, effectively ensuring the corrosion resistance of the inside of the pipe body and improving the overall performance and service life of the drill pipe.

Description

Technical Field

[0001] This invention relates to a composite bimetallic drill pipe and its manufacturing method, and relates to the field of drilling tools for oil and gas exploration. Background Technology

[0002] In the exploration and development of oil and natural gas, the strata contain CO2, O2, H2S, Cl- - Corrosive media can easily corrode the inner surface of drill pipes, affecting their safety and service life, causing material loss and environmental pollution. In severe cases, it can lead to drill pipe puncture or breakage, which can easily cause major safety accidents.

[0003] Currently, corrosion protection measures for drill pipes typically include coating with organic liquids or powders, and chromium plating inside the drill pipe. However, coatings formed by organic liquids or powders are prone to embrittlement, are not resistant to strong acids or alkalis, have a short service life, and are not resistant to high temperatures or wear, making them easily damaged. Chromium plating involves complex preparation processes, requires acid pickling, and is prone to porosity during electroplating, making wastewater treatment difficult and detrimental to environmental protection and the ecological environment. Furthermore, once the coatings formed by the above two methods are damaged, they will exacerbate the corrosion of the inner wall of the drill pipe, increasing the risk of drill pipe failure. Summary of the Invention

[0004] This invention provides a composite bimetallic drill pipe and its preparation method, which can reduce the risk of corrosion on the inner wall of the drill pipe and improve the overall performance and service life of the drill pipe.

[0005] The first aspect of this invention provides a method for preparing a composite bimetallic drill pipe, the method comprising the following steps:

[0006] A drill pipe joint is prepared, the drill pipe joint including a drill pipe joint body and a first corrosion-resistant alloy layer disposed on the inner wall of the drill pipe joint body, and the first corrosion-resistant alloy layer located on the inner wall of a first region of the drill pipe joint is removed, the first region being located at the weld neck end of the drill pipe joint;

[0007] A drill pipe body is prepared, the drill pipe body including a drill pipe body body and a second corrosion-resistant alloy layer disposed on the inner wall of the drill pipe body body; the second corrosion-resistant alloy layer located on the inner wall of a second region of the drill pipe body is removed, the second region being located at the end of the drill pipe body;

[0008] Friction welding is performed on the end of the first region of the drill pipe joint and the end of the second region of the drill pipe body. After welding, a third corrosion-resistant alloy layer is applied to the inner wall of the weld area of ​​the drill pipe joint and the drill pipe body, and the third corrosion-resistant alloy layer is fused with the first corrosion-resistant alloy layer and the second corrosion-resistant alloy layer into one piece.

[0009] In one specific embodiment, the preparation of the drill pipe joint includes the following steps:

[0010] A drill pipe joint body is prepared, and the inner wall of the drill pipe joint body is processed to obtain an inner spiral groove. The first corrosion-resistant alloy tube is then bonded to the inner wall of the drill pipe joint body through the inner spiral groove to obtain the drill pipe joint.

[0011] In one specific embodiment, the method further includes:

[0012] The drill pipe joint body is heated to 280-320°C and held for 30-45 minutes. The first corrosion-resistant alloy tube body, which is forged in the die, is then cooled at -40-60°C and held for 5-10 minutes before being bonded to the inner wall of the drill pipe joint body.

[0013] In one specific embodiment, the width of the inner spiral groove is less than 0.5 mm and the depth is less than 0.3 mm.

[0014] In one specific embodiment, the preparation of the drill pipe body includes the following steps:

[0015] The drill pipe body is obtained by metallurgically bonding a second corrosion-resistant alloy layer to the inner wall of the drill pipe body.

[0016] In one specific embodiment, the method further includes:

[0017] Before removing the second corrosion-resistant alloy layer located in the second region of the drill pipe body, the drill pipe body is upset.

[0018] In one specific embodiment, the thickness of the first corrosion-resistant alloy layer, the second corrosion-resistant alloy layer, and the third corrosion-resistant alloy layer is 0.8 to 1.2 mm.

[0019] In one specific embodiment, the axial length of the first region and the second region is 10 to 13 mm.

[0020] In one specific embodiment, the first corrosion-resistant alloy layer, the second corrosion-resistant alloy layer, and the third corrosion-resistant alloy layer comprise 316L alloy, and the drill pipe joint body and the drill pipe tube body comprise carbon steel.

[0021] A second aspect of the present invention provides a composite bimetallic drill pipe prepared by any of the above-described preparation methods, comprising a drill pipe joint and a drill pipe body welded together. The drill pipe joint includes a drill pipe joint body and a first corrosion-resistant alloy layer located on the inner wall of the drill pipe joint body. The drill pipe body includes a drill pipe body body and a second corrosion-resistant alloy layer located on the inner wall of the drill pipe body body. The drill pipe joint and the drill pipe body are welded together to form a weld. The inner wall of the weld between the drill pipe joint and the drill pipe body includes a third corrosion-resistant alloy layer, which is fused together with the first and second corrosion-resistant alloy layers.

[0022] The implementation of this invention has at least the following advantages:

[0023] 1. According to the preparation method provided by the present invention, a complete corrosion-resistant alloy layer is formed on the entire inner wall of the drill pipe. The inner walls of the pipe body and the joint are made of the same corrosion-resistant material, making the welding and fusion process of the corrosion-resistant material layer on the inner wall of the drill pipe more reliable and effectively ensuring the corrosion resistance of the pipe body. In addition, since the strength of the alloy layer is obviously higher than that of the organic coating, it has the characteristics of wear resistance and damage resistance, realizing the ability of the inner wall of the pipe to resist erosion, wear, and mechanical damage (such as scratches on the inner wall when logging instruments are installed in the pipe body), significantly improving the comprehensive performance and service life of the inner wall of the drill pipe, and is suitable for drilling conditions such as high temperature, acid, and alkaline conditions. Furthermore, the manufacturing method provided by the present invention does not use chemical substances and does not generate waste liquid, dust, etc., resulting in zero pollution to the environment.

[0024] 2. This invention combines the drill pipe joint body and the corrosion-resistant alloy layer through an internal thread groove composite method, which effectively improves the bonding strength between the inner corrosion-resistant alloy layer and the outer carbon steel metal pipe, and prevents separation during pipe tensile and compressive deformation, thus effectively ensuring the composite effect. Attached Figure Description

[0025] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic flowchart of a method for preparing a composite bimetallic drill pipe according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the drill pipe joint body prepared in step 101;

[0028] Figure 3 This is a schematic diagram of the drill pipe joint prepared in step 102.

[0029] Figure 4 This is a schematic diagram of the drill pipe joint prepared in step 103.

[0030] Figure 5 This is a schematic diagram of the drill pipe body prepared in step 201;

[0031] Figure 6 This is a schematic diagram of the drill pipe body prepared in step 202;

[0032] Figure 7 This is a schematic diagram of the welding between the drill pipe joint and the drill pipe body according to an embodiment of the present invention;

[0033] Figure 8 This is a schematic diagram of the structure of a composite bimetallic drill pipe provided in an embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1: First drill pipe joint;

[0036] 1-1: First drill pipe joint body;

[0037] 1-2: The first corrosion-resistant alloy layer on the inner wall of the first drill pipe joint;

[0038] 1-3: The end of the first drill pipe joint;

[0039] 1-4: Internal thread groove;

[0040] 2: Second drill pipe joint;

[0041] 2-1: Second drill pipe body;

[0042] 2-2: The first corrosion-resistant alloy layer on the inner wall of the second drill pipe joint;

[0043] 2-3: End of the second drill pipe joint;

[0044] 3: Drill pipe body;

[0045] 3-1: Drill pipe body:

[0046] 3-2: Second corrosion-resistant alloy layer;

[0047] 3-3: End of drill pipe body;

[0048] 4: Welds;

[0049] 5: Third corrosion-resistant alloy layer. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] A drill pipe is a metal tube used to connect the surface equipment of a drilling rig to the bottom-end equipment of the well. It includes a drill pipe joint and a drill pipe body. To reduce the risk of corrosion on the inner wall of the drill pipe and improve its overall performance and service life, this invention forms a complete corrosion-resistant alloy layer on the inner wall of the drill pipe and provides a method for preparing a composite bimetallic drill pipe. Figure 1 A flowchart of a method for preparing a composite bimetallic drill pipe according to an embodiment of the present invention is shown below. Figure 1 As shown, the preparation method includes the following steps:

[0052] Step 100: Prepare a drill pipe joint, the drill pipe joint including a drill pipe joint body and a first corrosion-resistant alloy layer disposed on the inner wall of the drill pipe joint body, and remove the first corrosion-resistant alloy layer located on the inner wall of a first region of the drill pipe joint, the first region being located at the weld neck end of the drill pipe joint.

[0053] First, a drill pipe joint with a corrosion-resistant alloy layer is prepared, and the corrosion-resistant alloy layer in the weld neck region is removed to facilitate welding to the drill pipe body. The drill pipe joint includes a first drill pipe joint and a second drill pipe joint, which are respectively connected to both ends of the drill pipe body. This embodiment describes in detail the preparation method of the first drill pipe joint as an example, specifically including the following steps:

[0054] Step 101: Prepare the drill pipe joint body 1-1;

[0055] First, the raw material is subjected to high-temperature die forging to form a blank of drill pipe joint body 1-1. The raw material of drill pipe joint body 1-1 can be carbon steel. The mold and die forging process used can be carried out according to conventional technical means in this field. It should be noted that the inner diameter of the blank of drill pipe joint body 1-1 should be 2 to 2.2 mm larger than the inner diameter of the finished drill pipe joint 1, so as to facilitate the subsequent composite of the first corrosion-resistant alloy tube.

[0056] Next, the inner wall of the drill pipe joint body 1-1 is machined to obtain an inner spiral groove 1-4. The inner spiral groove 1-4 is located on the inner wall of the drill pipe joint body 1-1 and extends inward in a spiral shape from the weld neck end of the drill pipe joint 1. The structure of the machined drill pipe joint body 1-1 is as follows: Figure 2 As shown.

[0057] Considering the combined effect of the first corrosion-resistant alloy layer 1-2 and the drill pipe joint body 1-1, the groove width W of the inner spiral groove 1-4 is less than 0.5 mm and the groove depth D is less than 0.3 mm.

[0058] Step 102: The first corrosion-resistant alloy tube body is bonded to the inner wall of the drill pipe joint body through the inner spiral grooves 1-4 to obtain the drill pipe joint.

[0059] The raw materials are subjected to high-temperature die forging to form the first corrosion-resistant alloy tube body. The outer diameter of the first corrosion-resistant alloy tube body is equal to the inner diameter of the drill pipe joint body 1-1. The raw material of the first corrosion-resistant alloy tube body can be 316L alloy. 316L alloy has excellent corrosion resistance and strength, realizing the erosion resistance, wear resistance and mechanical damage resistance of the inner wall of the tube body, significantly improving the comprehensive performance and service life of the drill pipe inner wall, and is suitable for use in drilling conditions such as high temperature, acid, and alkaline conditions.

[0060] Furthermore, the wall thickness of the first corrosion-resistant alloy tube is 0.8 to 1.2 mm.

[0061] After high-temperature die forging, the drill pipe joint body 1-1 is heated to 280-320℃ and held for 30-45 minutes. The first corrosion-resistant alloy tube, formed by die forging, is cooled at -40--60℃ and held for 5-10 minutes before being bonded to the inner wall of the drill pipe joint body 1-1 at high temperature. The first corrosion-resistant alloy tube is pressed against the inner wall of the drill pipe joint body 1-1. The slight deformation of the alloy tube causes it to embed into the inner spiral groove 1-4, thus bonding the drill pipe joint body 1-1 and the first corrosion-resistant alloy tube together. A first corrosion-resistant alloy layer 1-2 is formed on the inner wall of the drill pipe joint body 1-1. The inner spiral groove 1-4 effectively increases the bonding force between the drill pipe joint body 1-1 and the first corrosion-resistant alloy layer 1-2. The prepared drill pipe joint 1-1 is as follows: Figure 3 As shown.

[0062] Step 103: Remove the first corrosion-resistant alloy layer located on the inner wall of the first region of the drill pipe joint, wherein the first region is located at the weld neck end of the drill pipe joint;

[0063] The drill pipe joint 1 is usually connected to the drill pipe body 3 by friction welding. However, friction welding inevitably results in material loss. In order to ensure that the welding is between the main body materials and avoid metal inclusions, it is necessary to remove a small portion of the first corrosion-resistant alloy layer 1-2 at the weld neck of the drill pipe joint 1. Considering that the axial length of the friction welding loss is on the order of millimeters, during the composite process of the first corrosion-resistant alloy layer 1-2, the first corrosion-resistant alloy layer 1-2 is covered on the inner wall of the drill pipe joint body 1-1. That is, the drill pipe joint body 1-1 and the end face of the first corrosion-resistant alloy layer 1-2 near the weld neck end 1-3 are flush to ensure the manufacturing quality of the joint.

[0064] The first corrosion-resistant alloy layer 1-2 of the first region wall of the drill pipe joint 1 is removed by turning. The weld neck end 1-3 of the first region near the drill pipe joint 1 is removed as follows: Figure 4 As shown, the axial length L of the first region is 10 to 13 mm.

[0065] Step 200: Prepare a drill pipe body, which includes a drill pipe body and a second corrosion-resistant alloy layer disposed on the inner wall of the drill pipe body; remove the second corrosion-resistant alloy layer located on the inner wall of the second region of the drill pipe body, the second region being located at the end of the drill pipe body.

[0066] A drill pipe body 3 with a second corrosion-resistant alloy layer 3-2 was prepared, and the second corrosion-resistant alloy layer 3-2 at its end was removed using the same method. The specific preparation method is described below:

[0067] Step 201: Prepare the drill pipe body and perform upsetting treatment on the drill pipe body;

[0068] First, the drill pipe body 3-1 is prepared by high-temperature die forging. Then, a second corrosion-resistant alloy layer 3-2 is laminated onto the inner wall of the drill pipe body 3-1 by metallurgical composite method to obtain the drill pipe body 3. The raw material of the drill pipe body 3-1 can be carbon steel, and the raw material of the second corrosion-resistant alloy layer 3-2 is 316L alloy. The specific die forging process, metallurgical composite process, and dimensions of the drill pipe body can all be carried out according to conventional technical means in this field.

[0069] Secondly, the conventional drill pipe body 3 has a relatively thin wall thickness and cannot be directly welded to the drill pipe joint 1. Therefore, it is necessary to upset a portion of the area near the end of the drill pipe body to increase the wall thickness at both ends of the drill pipe body 3. Figure 5 This is a schematic diagram of the structure of the drill pipe body prepared in step 201, as shown below. Figure 5 As shown, the wall thickness of the end 3-3 where the drill pipe body 3 connects to the first drill pipe joint 1 and the second drill pipe joint 2 is greater than the wall thickness of the middle part, which facilitates subsequent friction welding with the drill pipe joint.

[0070] Step 202: Remove the second corrosion-resistant alloy layer located in the second region of the drill pipe body, the second region being located near the end of the drill pipe body;

[0071] The second corrosion-resistant alloy layer 3-2 in the second region of the drill pipe body 3 is removed by turning. The second region is located near the end 3-3 of the drill pipe body 3. The resulting drill pipe body 3 is as follows: Figure 6 As shown, the axial length of the second region is 10–13 mm.

[0072] Step 300: Friction welding is performed on the end of the first region of the drill pipe joint and the end of the second region of the drill pipe body. After welding, a third corrosion-resistant alloy layer is applied to the inner wall of the weld area of ​​the drill pipe joint and the drill pipe body, and the third corrosion-resistant alloy layer is fused with the first corrosion-resistant alloy layer and the second corrosion-resistant alloy layer into one piece.

[0073] Based on the preparation of drill pipe joint 1 and drill pipe body 3, the two are welded together by friction welding, and a third corrosion-resistant alloy layer is applied to the inner wall near the weld. The specific steps include the following:

[0074] Step 301: Friction weld the end of the first region of the drill pipe joint to the end of the second region of the drill pipe body;

[0075] Figure 7 This is a schematic diagram of the welding between the drill pipe joint and the drill pipe body in step 301, as shown below. Figure 7 As shown, the end faces of the drill pipe joint 1 prepared in step 100 and the drill pipe body 3 prepared in step 200 are brought into contact and then welded together by friction welding. Friction welding can be performed according to conventional techniques in this field.

[0076] Friction welding forms weld 4. Since the resulting weld 4 will have burrs, it is necessary to process weld 4 to remove the burrs so that the inner diameter of the weld is 2 to 2.2 mm smaller than the inner diameter of the joint.

[0077] Step 302: After welding, a third corrosion-resistant alloy layer is applied to the inner wall of the weld area of ​​the drill pipe joint and the drill pipe body, and the third corrosion-resistant alloy layer is fused with the first corrosion-resistant alloy layer and the second corrosion-resistant alloy layer into one piece.

[0078] Continue to refer to Figure 7 After the welding in step 301 is completed, the weld 4 is subjected to local heat treatment, and a third corrosion-resistant alloy layer 5 is applied to the inner wall of the drill pipe joint 1 and the drill pipe body 3 near the weld 4. The application of the welding layer is a type of surfacing welding, which can be carried out according to conventional technical means in this field.

[0079] During the welding process, the two ends of the third corrosion-resistant alloy layer 5 are fused together with the first corrosion-resistant alloy layer 1-2 and the second corrosion-resistant alloy layer 3-2 to ensure the formation of a complete corrosion-resistant alloy layer on the inner wall of the drill pipe. After the welding is completed, the third corrosion-resistant alloy layer 5 is further processed so that the third corrosion-resistant alloy layer 5 is flush with the first corrosion-resistant alloy layer 1-2 and the second corrosion-resistant alloy layer 3-2, that is, the thickness of the first corrosion-resistant alloy layer 1-2, the second corrosion-resistant alloy layer 2-2 and the third corrosion-resistant alloy layer 5 is the same. Specifically, the thickness of the corrosion-resistant alloy layer is 0.8 to 1.2 mm.

[0080] The second drill pipe joint 2 is connected to the other end of the drill pipe body 3. Its preparation method and welding method with the drill pipe body 3 are the same as those of the first drill pipe joint 1. The present invention will not be described in detail here.

[0081] The composite bimetallic drill pipe prepared according to the above preparation method is as follows: Figure 8 As shown, the system includes a first drill pipe joint 1, a second drill pipe joint 2, and a drill pipe body 3. The first drill pipe joint 1 and the second drill pipe joint 2 are respectively connected to the two ends of the drill pipe body 3. The first drill pipe joint 1 includes a drill pipe joint body 1-1 and a first corrosion-resistant alloy layer 1-2 located on the inner wall of the drill pipe joint body 1-1. The second drill pipe joint 2 includes a second drill pipe joint body 2-1 and a first corrosion-resistant alloy layer 2-2 located on the inner wall of the second drill pipe joint body 2-1. The drill pipe body 3 includes a drill pipe body 3-1 and a second corrosion-resistant alloy tube body 3-2 located on the inner wall of the drill pipe body 3-1.

[0082] The ends 1-3 of the first drill pipe joint 1 and the ends 2-3 of the second drill pipe joint 2 are respectively connected to the two ends 3-3 of the drill pipe body 3 by friction welding to form a weld 4. The inner walls of the first drill pipe joint 1, the second drill pipe joint 2 and the drill pipe body 3 near the weld 4 are covered with a third corrosion-resistant alloy layer 5. The third corrosion-resistant alloy layer 5 is fused together with the first corrosion-resistant alloy layer 1-2 on the inner wall of the first drill pipe joint, the first corrosion-resistant alloy layer 2-2 on the inner wall of the second drill pipe joint and the second corrosion-resistant alloy layer 3-2, and the thickness of the corrosion-resistant alloy layers is the same, thereby forming a complete corrosion-resistant alloy layer on the inner wall of the drill pipe.

[0083] In summary, the preparation method provided by this invention forms a complete corrosion-resistant alloy layer on the entire inner wall of the drill pipe. The inner walls of the pipe body and joints are made of the same corrosion-resistant material, making the welding and fusion process of the corrosion-resistant material layer on the inner wall of the drill pipe more reliable and effectively ensuring the corrosion resistance of the pipe body. In addition, since the strength of the alloy layer is significantly higher than that of the organic coating, it has the characteristics of wear resistance and damage resistance, realizing the ability of the inner wall of the pipe to resist erosion, wear, and mechanical damage (such as scratches on the inner wall when logging instruments are installed inside the pipe). This significantly improves the comprehensive performance and service life of the inner wall of the drill pipe and is suitable for drilling conditions such as high temperature, acid, and alkaline conditions. Furthermore, the manufacturing method provided by this invention does not use chemical substances and does not generate waste liquid, dust, etc., resulting in zero pollution to the environment.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these 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 the present invention.

Claims

1. A method for preparing a composite bimetallic drill pipe, characterized in that, The method includes the following steps: A drill pipe joint body is prepared, and an inner spiral groove is machined on the inner wall of the drill pipe joint body. The drill pipe joint body is heated to 280~320℃ and held for 30~45 minutes. Then, a first corrosion-resistant alloy tube body formed by die forging is cooled at -40~-60℃ and held for 5~10 minutes. The tube body is then bonded to the inner wall of the drill pipe joint body through the inner spiral groove to prepare the drill pipe joint. The drill pipe joint includes the drill pipe joint body and a first corrosion-resistant alloy layer disposed on the inner wall of the drill pipe joint body. The first corrosion-resistant alloy layer located in the inner wall of a first region of the drill pipe joint is removed. The first region is located at the weld neck end of the drill pipe joint. The drill pipe body is prepared by high-temperature die forging process, and then a second corrosion-resistant alloy layer is laminated on the inner wall of the drill pipe body by metallurgical composite method to prepare the drill pipe body; wherein, the drill pipe body includes the drill pipe body and the second corrosion-resistant alloy layer disposed on the inner wall of the drill pipe body, and the second corrosion-resistant alloy layer located on the inner wall of the second region of the drill pipe body is removed, the second region being located at the end of the drill pipe body; Friction welding is performed on the end of the first region of the drill pipe joint and the end of the second region of the drill pipe body. After welding, a third corrosion-resistant alloy layer is applied to the inner wall of the drill pipe joint and the drill pipe body near the weld area, and the third corrosion-resistant alloy layer is fused with the first corrosion-resistant alloy layer and the second corrosion-resistant alloy layer to form a complete corrosion-resistant alloy layer on the inner wall of the drill pipe joint and the inner wall of the drill pipe body. Specifically, the drill pipe body is upset before the second corrosion-resistant alloy layer located on the inner wall of the second region of the drill pipe body is removed.

2. The preparation method according to claim 1, characterized in that, The width of the inner spiral groove is less than 0.5 mm and the depth is less than 0.3 mm.

3. The preparation method according to claim 1, characterized in that, The first corrosion-resistant alloy layer, the second corrosion-resistant alloy layer, and the third corrosion-resistant alloy layer have the same thickness, and the thickness of the corrosion-resistant alloy layer is 0.8~1.2mm.

4. The preparation method according to claim 1, characterized in that, The axial length of the first region is 10~13mm, and the axial length of the second region is 10~13mm.

5. The preparation method according to claim 1, characterized in that, The first corrosion-resistant alloy layer, the second corrosion-resistant alloy layer, and the third corrosion-resistant alloy layer are all made of 316L alloy, and the drill pipe joint body and the drill pipe tube body are made of carbon steel.

Images