A titanium alloy drill rod with equal inner diameter

Abstract

The invention discloses a titanium alloy drill rod with equal inner diameter, wherein the inner diameters of the internal thread joint, the external thread joint and the drill rod body of the main part of the titanium alloy drill rod with equal inner diameter are equal, and the three are integrally formed by extrusion molding, and there is no weld at the connection of the three, which effectively solves the problem of poor material performance at the friction weld between the drill rod body and the drill rod joint. At the same time, due to the integral extrusion molding, a production process flow of the drill rod is reduced, and the loss of titanium alloy raw materials and the manufacturing cost in the production process of the drill rod are reduced; when the titanium alloy drill rods with equal inner diameter are connected for use, because the entire inner diameter does not change, the wear resistance of the drill rod body is improved, the drilling fluid displacement and the water power at the drill bit are increased, and the cost performance of the titanium alloy drill rod is improved.

Description

[Technical field]

[0001] The invention belongs to the field of drill rods, and in particular relates to a titanium alloy drill rod with a constant inner diameter. [Background technology]

[0002] The friction welded drill pipe used in oil and gas exploration and development is made of a drill pipe body with two ends connected to a threaded internal thread joint and an external thread joint by friction welding. The drill pipe body and the drill pipe joint are first manufactured into semi-finished products using different processes: the drill pipe body is a thin-walled seamless pipe. Before friction welding with the joint, the pipe end needs to be upset to obtain a larger cross-sectional area, and then the pipe body is subjected to overall heat treatment to obtain the material properties of the drill pipe body. The drill pipe joint is formed by die forging or processing from round bar material, and then heat treated to obtain the material properties of the joint. Finally, the pipe body and the joint are friction welded, and the weld is locally heat treated to obtain the performance of the weld. Therefore, in the friction welding drill pipe standard, different material performance indicators are set for the drill pipe body, drill pipe joint and weld, and the inner diameter at the weld is much smaller than the inner diameter of the pipe body, causing high-pressure drilling fluid to generate eddy currents at the inner diameter change point, increasing hydraulic friction loss and corrosion of the inner wall of the drill pipe.

[0003] Titanium alloy drill pipe is a precious metal, and its material cost is about 25 times that of steel drill pipe. At the same time, the heat conduction of titanium alloy material is slow, and the local heat treatment of weld is technically difficult. The use of traditional steel drill pipe manufacturing process to manufacture titanium alloy drill pipe not only consumes a lot of titanium alloy material, increases the manufacturing cost of weld treatment, but also has poor weld performance, which reduces the cost performance of titanium alloy drill pipe. [Summary of the invention]

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a titanium alloy drill pipe with a constant inner diameter, which can solve the problem of poor material properties at the friction weld between the drill pipe body and the drill pipe joint, reduce the loss of titanium alloy raw materials and manufacturing costs in the drill pipe production process, increase the inner diameter size of the drill pipe body, improve the wear resistance of the drill pipe body, increase the drilling fluid displacement and the water power at the drill bit, and improve the cost performance of the titanium alloy drill pipe.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A titanium alloy drill pipe with equal inner diameter comprises a drill pipe body, the two ends of which are respectively connected to an external thread joint and an internal thread joint; the external thread joint, the internal thread joint and the drill pipe body are extruded into one piece; the inner vertical section of the internal thread joint, the external thread joint and the drill pipe body have the same inner diameters.

[0007] A further improvement of the present invention is:

[0008] Preferably, the drill pipe body includes an outer end portion, a connecting portion and a middle portion, the two ends of the middle portion are respectively connected to the inner end of a connecting portion, the outer end of each connecting portion is connected to the inner end of an outer end portion; the outer end of an outer end portion is connected to an external threaded joint, and the outer end of the other outer end portion is connected to an internal threaded joint.

[0009] Preferably, the outer diameter of the middle portion is 1.045-1.067 times the outer diameter of the connecting portion.

[0010] Preferably, the length of the middle portion is 0.053-0.084 of the length of a titanium alloy drill rod with the same inner diameter.

[0011] Preferably, the outer diameter of the outer end portion is 1.137-1.157 times the outer diameter of the connecting portion.

[0012] Preferably, a layer of wear-resistant material is disposed outside the middle portion; the thickness of the wear-resistant material is 1-2 mm, and the hardness is HRC55-60.

[0013] Preferably, the external threaded joint includes an external vertical section and a tapered section with equal inner diameters and connected, the inner end and outer end of the external vertical section are connected, and the outer end of the external vertical section is connected to the tapered section; the outer diameter of the outer end of the tapered section is smaller than the outer diameter of the inner end of the tapered section, the outer diameter of the inner end of the tapered section is smaller than the outer diameter of the external vertical section, and the outer diameter of the external vertical section is larger than the outer diameter of the outer end.

[0014] Preferably, the internal threaded joint includes a connected internal vertical section and a gradually expanding section; the inner end and the outer end of the internal vertical section are connected, and the outer end of the internal vertical section is connected to the gradually expanding section; the inner diameters of the outer end and the internal vertical section are equal; the inner diameter of the inner end of the gradually expanding section is larger than the inner diameter of the internal vertical section, and the inner diameter of the outer end of the gradually expanding section is larger than the inner diameter of the inner end of the gradually expanding section.

[0015] Preferably, an elevator step is provided at the connection between the internal thread joint and the drill pipe body, and the angle α between the outer side of the elevator step and the axis of the drill pipe body is 17-19°.

[0016] Preferably, a circular arc segment is provided at the connection between the external thread connector and the drill pipe body, and the radius R of the circular arc segment is 80-100 mm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The invention discloses a titanium alloy drill rod with equal inner diameter, wherein the inner diameters of the internal thread joint, the external thread joint and the drill rod body of the main part of the titanium alloy drill rod with equal inner diameter are equal, and the three are integrally formed by extrusion molding, and there is no weld at the connection of the three, which effectively solves the problem of poor material performance at the friction weld between the drill rod body and the drill rod joint. At the same time, due to the integral extrusion molding, a production process flow of the drill rod is reduced, and the loss of titanium alloy raw materials and the manufacturing cost in the production process of the drill rod are reduced; when the titanium alloy drill rods with equal inner diameter are connected and used, because the entire inner diameter does not change, the erosion and wear resistance of the drill rod body is improved, the drilling fluid displacement and the water power at the drill bit are increased, and the cost performance of the titanium alloy drill rod is improved.

[0019] Furthermore, according to actual application conditions, the length of the middle portion is limited, the wall thickness of the middle portion is increased, and the friction and wear resistance of the middle portion of the tube body is improved.

[0020] Furthermore, a layer of wear-resistant material is added to the middle portion to further improve the wear resistance of the middle portion pipe body.

[0021] Furthermore, the wall thickness of the outer end is increased to prevent the internal thread joint or the external thread joint from breaking due to the thin connection during thread processing.

[0022] Furthermore, the external thread is provided with a tapered section, and the internal thread joint is provided with a gradually expanding section. When the external and internal threads are processed, the processing allowance is small, saving raw materials. At the same time, when titanium alloy drill pipes of equal inner diameter are connected for use, the inner diameter of the connected titanium alloy drill pipes of equal inner diameter remains unchanged.

[0023] Furthermore, an elevator step is provided on the side of the internal thread joint to facilitate the clamping tool to apply axial force to the titanium alloy drill rod with equal inner diameter when the drill rod is used.

[0024] Furthermore, arc segments are provided to reduce stress concentration at the connection.

Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the existing friction welding drill pipe structure;

[0026] Figure 2 This is a schematic diagram of the structure of a titanium alloy drill rod with a constant inner diameter according to the present invention;

[0027] Among them: 1-external threaded joint; 2-internal threaded joint; 3-drill pipe body; 4-weld; 5-wear-resistant material; 1-1-external vertical section; 1-2 tapered section; 2-1-internal vertical section; 2-2-gradually expanding section; 3-1 middle part; 3-2-connecting part; 3-3-external end part; 14-lifting card step. [Specific implementation method]

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings; the present invention discloses a titanium alloy drill rod with a constant inner diameter.

[0029] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] See also Figure 1 The friction welded drill pipe of the prior art comprises an external thread joint 1, an internal thread joint 2 matched with the external thread joint 1, a drill pipe body 3, and two welds 4 used to respectively connect the drill pipe body 3 with the external thread joint 1 and the internal thread joint 2; when the specification of the drill pipe body 3 of the friction welded drill pipe is S135 88.9×9.35mm, the outer diameters of the external thread joint 1 and the internal thread joint 2 are 127mm, the inner diameter of the drill pipe body 3 is 70.2mm, and the outer diameters of the two welds 4 are 98.4mm and the inner diameters are 54.0mm.

[0031] See also Figure 2 , is a schematic structural diagram of a titanium alloy drill pipe of equal inner diameter according to the present invention, comprising a drill pipe body 3, the two ends of which are respectively connected to an external threaded joint 1 and an internal threaded joint 2; the external threaded joint 1, the internal threaded joint 2 and the drill pipe body 3 are integrally extruded, and there is no weld between the three.

[0032] The inner diameter of the drill pipe body 3 remains unchanged. According to the thickness of its outer wall, it is divided into an outer end portion 3-3, a connecting portion 3-2 and a middle portion 3-1. The middle portion 3-1 is located in the middle of the entire drill pipe body 3 in the length direction. The transverse center line of the middle portion 3-1 is the transverse center line of the entire drill pipe body 3. The two ends of the middle portion 3-1 are respectively connected to the inner end of a connecting portion 3-2, and the outer end of each connecting portion 3-2 is connected to an outer end portion 3-3. The inner diameter thickness of the outer end portion 3-3, the connecting portion 3-2 and the middle portion 3-1 is equal. The wall thickness of the connecting part 3-2 is the thinnest. The outer diameter of the connecting part 3-2 is set to D2, the outer diameter of the middle part 3-1 is set to D1, and the outer diameter of the outer end part 3-3 is set to D3. D1 / D2=1.045-1.067, D3 / D2=1.137-1.157; the length of the middle part 3-1 accounts for 0.053%-0.084% of the total length of the drill pipe; a layer of wear-resistant material 5 is welded on the outer surface of the middle part 3-1, the thickness of the wear-resistant material 5 is 1-2mm, and the hardness is HRC55-60. The wear-resistant material 5 is preferably a chromium-based alloy. When the friction welding drill pipe is in operation, the entire drill pipe body 3 will be subjected to radial force due to rotation. The drill pipe body 3 itself is relatively long, so that the middle part 3-1 is far away from the two ends, making the middle part 3-1 more susceptible to wear relative to the connecting part, which may cause breakage. Therefore, it is necessary to increase the wall thickness here. At the same time, a layer of wear-resistant material 5 is welded on the outside of the middle part 3-1 to increase the wear resistance here. The two outer ends 3-3 are respectively connected to the external threaded joint 1 and the internal threaded joint 2. Because the wall thickness of the external threaded joint 1 and the internal threaded joint 2 is large, the wall thickness of the two outer ends 3-3 is increased to ensure a smooth transition of the rigidity of the entire drill pipe.

[0033] The inner diameter of the external threaded joint 1 is equal to the inner diameter of the drill pipe body 3, the external threaded joint 1 is connected to an outer end 3-3, and the other outer end 3-3 of the drill pipe body 3 is connected to the internal threaded joint 2; the external threaded joint 1 includes an external vertical section 1-1 and a tapered section 1-2 with different outer diameters and equal inner diameters, the inner end of the external vertical section 1-1 is connected to the outer end of the outer end 3-3, and the outer end of the external vertical section 1-1 is connected to the inner end of the tapered section 1-2; along the axis of the titanium alloy drill pipe with equal inner diameter, from the center of the titanium alloy drill pipe with equal inner diameter to the direction of the external threaded joint 1, the outer diameter of the tapered section 1-2 gradually decreases, wherein the outer diameter of the inner end of the tapered section 1-2 is smaller than the outer diameter of the external vertical section 1-1, and the outer diameter of the outer end of the tapered section 1-2 is smaller than the outer diameter of the inner end of the tapered section 1-2; the purpose of setting the tapered section 1-2 is to cooperate with the following gradually expanding section 2-2.

[0034] The inner tube of the internal threaded joint 2 includes two parts with different inner diameters, an internal vertical section 2-1 and a gradually expanding section 2-2. The outer end 3-3 of the drill pipe body 3 is connected to the inner end of the internal vertical section 2-1, and the inner diameters of the two parts are the same; the outer end of the internal vertical section 2-1 is connected to the inner end of the gradually expanding section 2-2, and the inner tube diameter of the gradually expanding section 2-2 is a gradually expanding shape. Along the axis of the titanium alloy drill pipe with the same inner diameter, from the center of the titanium alloy drill pipe with the same inner diameter to the direction of the internal threaded joint 2, the inner tube diameter of the gradually expanding section 2-2 is The gradually expanding section 2-2 gradually increases in diameter and the connection between the inner end of the gradually expanding section 2-2 and the outer end of the internal vertical section 2-1 is in a step shape. The inner diameter of the inner end of the gradually expanding section 2-2 is larger than the inner diameter of the internal vertical section 2-1, and the inner diameter of the outer end of the gradually expanding section 2-2 is larger than the inner diameter of the inner end of the gradually expanding section 2-2. The gradually expanding inner tube diameter of the gradually expanding section 2-2 is mainly used for when titanium alloy drill pipes with equal inner diameters are connected to each other, the gradually expanding section 2-2 can cooperate with the tapering section 1-2 to realize the connection and use of the internal threaded joint 2 and the external threaded joint 1.

[0035] The outer diameter of the entire external threaded joint 12 is equal to the outer diameter of the external vertical section 1 - 1 and is set to D4, where D4 / D2=1.43.

[0036] From the above description, it can be seen that all changes in the equal inner diameter titanium alloy drill pipe in the present invention basically occur in the change of wall thickness. Different wall thicknesses are set according to the different functions of different parts, and the inner diameter has not changed except that the gradually expanding section 2-2 of the internal threaded joint 2 has undergone certain changes. When the equal inner diameter titanium alloy drill pipe is connected for use, after the gradually expanding section 2-2 and the gradually contracting section 1-2 are matched, the inner diameter of the connected equal inner diameter titanium alloy drill pipe remains unchanged. This inner diameter structure can directly reduce the hydraulic friction and erosion of the drilling fluid, improve the wear resistance of the drill pipe body, increase the drilling fluid displacement and the water power at the drill bit, and improve the comprehensive performance and cost performance of the titanium alloy drill pipe.

[0037] An elevator step 14 is formed by extrusion on the outside of the connection between the drill pipe body 3 and the internal threaded joint 2. The elevator step 14 is arranged in a circle around the connection, and the angle α between the side of the elevator step 14 and the axis of the drill pipe body 3 is 17 to 19°; when titanium alloy drill pipes of equal inner diameter are connected to each other, the elevator step 14 can facilitate the use of the clamping tool and provide a contact platform for the clamping tool, so that the clamping tool can apply axial force to the titanium alloy drill pipes of equal inner diameter.

[0038] The outside of the connection between the drill pipe body 3 and the external threaded joint 1 is provided with an arc segment transition by extrusion molding, and the arc segment is arranged around the connection, and the arc radius R of the arc segment is 80-100 mm. The setting of the arc segment can reduce stress concentration, so that the connection between the external threaded joint 1 and the drill pipe body 3 is evenly stressed.

[0039] Example

[0040] When the titanium alloy drill pipe of equal inner diameter is based on the above-mentioned S135, the specific dimensions of the drill pipe body 1 after the structural improvement of the present invention are as follows: the inner diameter of the drill pipe body 3, the inner diameter of the external threaded joint 1 and the inner diameter of the vertical section 121 are all 70.2, the outer diameter of the connecting part 3-2 is 89mm, and the length of the titanium alloy drill pipe of equal inner diameter is 9500mm; the outer diameters of the external vertical sections 1-1 of the internal threaded joint 2 and the external threaded joint 1 are 127mm, and the outer diameter of the middle part 3-1 is 92.9~94.9mm; the thickness of the two outer end parts 3-3 is 82.4~84.2mm, and the wall thickness of 3-3 of the two outer end parts is 12.2~14.0mm.

[0041] A wear-resistant material layer 5 is welded on the outer side of the middle part 3-1, the thickness of the wear-resistant material layer 5 is 1 to 2 mm, and the hardness is HRC55 to 60; an elevator step 14 is formed by extrusion between the outer end 3-3 and the internal threaded joint 2, and the angle of the elevator step 14 is 17 to 19°; an arc segment is formed by extrusion between the outer end 3-3 and the external threaded joint 1, and the arc radius of the arc segment is 80 to 100 mm.

[0042] The above description is only 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A titanium alloy drill pipe with a constant inner diameter, characterized in that: The drill pipe body (3) comprises a drill pipe body (3), wherein two ends of the drill pipe body (3) are respectively connected to an external threaded joint (1) and an internal threaded joint (2); the external threaded joint (1), the internal threaded joint (2) and the drill pipe body (3) are extruded and formed into one piece; the internal vertical section (2-1) of the internal threaded joint (2), the external threaded joint (1) and the drill pipe body (3) have the same inner diameter; The drill pipe body (3) comprises an outer end portion (3-3), a connecting portion (3-2) and a middle portion (3-1); the two ends of the middle portion (3-1) are respectively connected to the inner end of a connecting portion (3-2); the outer end of each connecting portion (3-2) is connected to the inner end of an outer end portion (3-3); the outer end of one outer end portion (3-3) is connected to an external threaded joint (1), and the outer end of another outer end portion (3-3) is connected to an internal threaded joint (2); The outer diameter of the outer end portion (3-3) is 1.137-1.157 times the outer diameter of the connecting portion (3-2); The outer diameter of the middle part (3-1) is 1.045-1.067 times the outer diameter of the connecting part (3-2); A circular arc section is provided at the connection between the external threaded joint (1) and the drill pipe body (3), and the radius R of the circular arc section is 80 to 100 mm; The external thread joint (1) comprises an external vertical section (1-1) and a tapered section (1-2) of equal inner diameter and connected; the inner end of the external vertical section (1-1) and the outer end (3-3) are connected; the outer end of the external vertical section (1-1) and the tapered section (1-2) are connected; the outer diameter of the outer end of the tapered section (1-2) is smaller than the outer diameter of the inner end of the tapered section (1-2); the outer diameter of the inner end of the tapered section (1-2) is smaller than the outer diameter of the external vertical section (1-1); and the outer diameter of the external vertical section (1-1) is larger than the outer diameter of the outer end (3-3); The internal thread joint (2) comprises an internal vertical section (2-1) and a gradually expanding section (2-2) which are connected; the inner end of the internal vertical section (2-1) is connected to an outer end (3-3), and the outer end of the internal vertical section (2-1) is connected to the gradually expanding section (2-2); the inner diameters of the outer end (3-3) and the internal vertical section (2-1) are equal; the inner diameter of the inner end of the gradually expanding section (2-2) is greater than the inner diameter of the internal vertical section (2-1), and the inner diameter of the outer end of the gradually expanding section (2-2) is greater than the inner diameter of the inner end of the gradually expanding section (2-2); An elevator step (14) is provided at the connection between the internal thread joint (2) and the drill pipe body (3), and an angle α between the outer side of the elevator step (14) and the axis of the drill pipe body (3) is 17-19°.

2. The titanium alloy drill rod with a constant inner diameter according to claim 1, characterized in that: The length of the middle part (3-1) is 0.053-0.084 of the length of the titanium alloy drill rod with the same inner diameter.

3. The titanium alloy drill rod with a constant inner diameter according to claim 1, characterized in that: A layer of wear-resistant material (5) is arranged outside the middle part (3-1); the wear-resistant material (5) has a thickness of 1-2 mm and a hardness of HRC55-60.

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