High-corrosion-resistance continuous pipe with variable wall thickness at inclined welding seam

Abstract

The high-corrosion-resistance continuous pipe with the variable wall thickness at the inclined weld joint comprises a first steel pipe, the first steel pipe is fixedly connected with a connecting pipe, and the other end of the connecting pipe is fixedly connected with a second steel pipe. According to the high-corrosion-resistance continuous pipe with the variable wall thickness at the inclined welding seam, due to the arrangement of the connecting pipe, the bending deformation service life of the inclined welding seam in the operation process is prolonged, the safety of the continuous pipe is improved, the continuous pipe is suitable for being used under the condition of a high-corrosion medium, and the problem that an existing high-corrosion-resistance continuous pipe is prone to failure at the inclined welding seam in the operation process is solved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to petroleum and natural gas pipe material technical field, and specifically relates to high corrosion resistance coiled tubing with variable wall thickness at inclined weld. BACKGROUND

[0002] Coiled tubing (CT, Coiled Tubing) is a new type of oil and gas pipe material with a single length of up to thousands of meters, high strength, high plasticity and certain corrosion resistance. Because coiled tubing technology has a series of technical advantages and operation advantages such as high efficiency, low cost, wide operation range and small land occupation, coiled tubing will play an increasingly important role in oil and gas field exploration, development, operation and yield increase, and has broad application prospects.

[0003] With the increasing difficulty of oil and gas exploration and development in China and the increasing number of unconventional oil and gas resource development, many complex oil and gas well engineering problems will appear. For example, in Tarim Basin, oil and gas wells are combined with ultra-deep, ultra-high pressure, ultra-high temperature and high corrosion, and the requirements for the comprehensive performance of coiled tubing such as strength, impact resistance and corrosion resistance have been further improved.

[0004] Traditional carbon steel coiled tubing cannot fully meet the production requirements of complex oil and gas well conditions, and corrosion-resistant alloy pipe is usually used instead. At present, the domestic and foreign corrosion-resistant coiled tubing products mainly include duplex stainless steel and austenitic stainless steel coiled tubing. Among them, 2205 duplex stainless steel coiled tubing has strong corrosion resistance in CO2 and a small amount of H2S corrosion medium, and the coiled tubing made of austenitic stainless steel has good CO2 corrosion resistance and pitting corrosion resistance, but the equal-wall-thickness corrosion-resistant coiled tubing is prone to failure at the butt joint of the inclined weld. SUMMARY

[0005] The utility model discloses a high corrosion resistance coiled tubing with variable wall thickness at inclined weld, which solves the problem of easy failure of the existing high corrosion resistance coiled tubing at the inclined weld during operation.

[0006] The utility model discloses the technical scheme that adopts is high corrosion resistance coiled tubing with variable wall thickness at inclined weld, and the utility model discloses the both ends of connecting pipe are all with first steel pipe, second steel pipe welding connection.

[0007] The utility model discloses the characteristics still lie in:

[0008] The both ends of the connecting pipe are welded to the first steel pipe and the second steel pipe.

[0009] The first steel pipe and the second steel pipe respectively extend into the connecting pipe, and the opposite ends of the first steel pipe and the second steel pipe are respectively welded to the inner wall of the connecting pipe.

[0010] The wall thickness of the first steel pipe is equal to the wall thickness of the second steel pipe.

[0011] The inner walls of both ends of the connecting pipe are provided with sawtooth-shaped bosses, the outer walls of both ends of the first steel pipe and the second steel pipe are provided with sawtooth-shaped grooves, the connecting pipe is connected with the first steel pipe and the second steel pipe through the sawtooth-shaped bosses and the sawtooth-shaped grooves, respectively, a sawtooth-shaped first weld is formed between the connecting pipe and the first steel pipe, and the angle of the sawtooth-shaped first weld is 30°-60°.

[0012] A sawtooth-shaped second weld is formed between the connecting pipe and the second steel pipe, and the angle of the sawtooth-shaped second weld is 30°-60°.

[0013] The wall thickness of the connecting pipe is 1.5 times of the wall thickness of the first steel pipe and the second steel pipe.

[0014] The length of the connecting pipe is 1% of the total length of the first steel pipe and the second steel pipe.

[0015] The high-corrosion-resistance continuous pipe with variable wall thickness at a bevel weld has the advantages that the connecting pipe is arranged, the bending deformation life of the bevel weld in the operation process is prolonged, the safety of the continuous pipe is improved, the continuous pipe is suitable for use in a high-corrosion medium condition, and the problem that the existing high-corrosion-resistance continuous pipe is prone to failure at the bevel weld in operation is solved.

[0016] The high-corrosion-resistance continuous pipe with variable wall thickness at a bevel weld provided by the utility model has the advantages that the connecting pipe is arranged, the bending deformation life of the bevel weld in the operation process is prolonged, the safety of the continuous pipe is improved, the continuous pipe is suitable for use in a high-corrosion medium condition, and the problem that the existing high-corrosion-resistance continuous pipe is prone to failure at the bevel weld in operation is solved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic view of the high-corrosion-resistance continuous pipe with variable wall thickness at a bevel weld of the utility model;

[0018] In the figure, 1 is a first steel pipe, 2 is a connecting pipe, 3 is a second steel pipe, 4 is a sawtooth-shaped first weld, and 5 is a sawtooth-shaped second weld. DETAILED DESCRIPTION

[0019] The utility model will be explained in detail in combination with the drawings and the specific implementation.

[0020] The high-corrosion-resistance continuous pipe with variable wall thickness at a bevel weld provided by the utility model has the advantages that the connecting pipe is arranged, the bending deformation life of the bevel weld in the operation process is prolonged, the safety of the continuous pipe is improved, the continuous pipe is suitable for use in a high-corrosion medium condition, and the problem that the existing high-corrosion-resistance continuous pipe is prone to failure at the bevel weld in operation is solved. Figure 1As shown, it comprises a first steel pipe 1, the first steel pipe 1 is fixedly connected with a connecting pipe 2, the other end of the connecting pipe 2 is fixedly connected with a second steel pipe 3; both ends of the connecting pipe 2 are welded with the first steel pipe 1 and the second steel pipe 3; the first steel pipe 1 and the second steel pipe 3 respectively extend into the connecting pipe 2, and the opposite ends of the first steel pipe 1 and the second steel pipe 3 are respectively welded to the inner wall of the connecting pipe 2; the wall thickness of the first steel pipe 1 is equal to that of the second steel pipe 3; the inner walls of both ends of the connecting pipe 2 are provided with sawtooth-shaped bosses, the outer walls of both ends of the first steel pipe 1 and the second steel pipe 3 are provided with sawtooth-shaped grooves, the connecting pipe 2 is connected with the first steel pipe 1 and the second steel pipe 3 through the sawtooth-shaped bosses and the sawtooth-shaped grooves, a sawtooth-shaped first weld 4 is formed between the connecting pipe 2 and the first steel pipe 1, the angle of the sawtooth-shaped first weld 4 is 30°-60°; a sawtooth-shaped second weld 5 is formed between the connecting pipe 2 and the second steel pipe 3, the angle of the sawtooth-shaped second weld 5 is 30°-60°; the wall thickness of the connecting pipe 2 is 1.5 times of the wall thickness of the first steel pipe 1 and the second steel pipe 3; the length of the connecting pipe 2 is 1% of the total length of the first steel pipe 1 and the second steel pipe 3.

[0021] The raw material chemical components of the first steel pipe 1, the connecting pipe 2 and the second steel pipe 3 are as follows:

[0022] C≤0.02%; Si≤0.70%; Mn≤1.5%; Cr: 24.5-27.5%; Ni: 5.5-7.5%; S≤0.02%; P≤0.02%; Mo: 3.5-5.5%; N: 0.28-0.37%; the rest is Fe;

[0023] The high corrosion-resistant continuous pipe with variable wall thickness at the inclined weld is manufactured according to the following steps:

[0024] Step 1, coil preparation;

[0025] Specifically, taking molten iron as the main raw material, alloying elements are added according to the designed chemical composition, and the coil is smelted and manufactured, and a coil with a length of more than 400 m is manufactured;

[0026] Step 2, coil slitting and butt welding;

[0027] Specifically, the prepared coil is cut into a steel strip with a suitable width of 50-300 mm through a slitting machine according to the continuous pipe specification; the butt welding process is used for the steel strip lengthening, the end parts of the front and rear two steel strips are processed into 30-60° sawtooth-shaped groove bevels before butt welding, and a certain length of thick wall steel strip is connected between the two steel strips, the two ends of the thick wall steel strip are processed into sawtooth-shaped bosses close to the side surfaces of the two steel strips, the sawtooth-shaped groove and the sawtooth-shaped boss are matched, the bevel is reasonably processed according to the thickness of the plate, the bevel is I-shaped, V-shaped or U-shaped, the welding process adopts friction stir welding, gas-protected laser welding, argon arc welding or plasma welding; the weld is heated to 1020-1100℃ for solid solution treatment after welding;

[0028] Step 3, preparing high corrosion-resistant continuous pipe with variable wall thickness at bevel weld;

[0029] According to the outer diameter and wall thickness requirements of the final product continuous pipe, the side of the steel strip is planed into I-shaped groove by milling method, and the width of the steel strip and the perpendicularity of the plate edge are accurately controlled; high-frequency induction welding, plasma welding or laser welding is used for welding, and inert gas with purity ≥ 99.99% is used as protective gas during the whole welding process; the bevel weld high corrosion-resistant continuous pipe with variable wall thickness is welded into a pipe with a diameter of Φ25.4-Φ88.9mm and a wall thickness of 2.4-6.4mm, the front steel strip coil is the first steel pipe 1, the rear steel strip coil is the second steel pipe 3, and the thick wall steel strip coil is the connecting pipe 2;

[0030] Step 4, heat treatment of longitudinal weld and whole pipe body.

[0031] After the longitudinal welding of the pipe is completed, the pipe is subjected to a certain amount of deformation by using a sizing method with an extrusion roller, and the whole pipe body is heated to 1020-1100℃ under an inert gas atmosphere by using a medium-frequency induction heating method, and is kept for 5-20min, and is cooled to room temperature, to obtain the finished pipe;

[0032] Step 5: winding on a reel;

[0033] The heat-treated continuous pipe is wound on a reel with a suitable core diameter by a coiling machine, and a continuous pipe with a length of more than 61m is continuously produced for transportation and use.

[0034] The bevel weld high corrosion-resistant continuous pipe prepared by the method has a tensile strength ≥552MPa, a yield strength ≥483MPa, an elongation ≥22%, an outer diameter range of Φ25.4-Φ88.9mm, a wall thickness range of 1.9-6.4mm, a length of more than 61m, and a hardness ≤22HRC, and under a corrosion condition with a pressure ≤0.1MPa, CO2 and a small amount of H2S, the corrosion rate is ≤0.076mm / a.

[0035] Example 1

[0036] The bevel weld high corrosion-resistant continuous pipe prepared by the method has a tensile strength ≥552MPa, a yield strength ≥483MPa, an elongation ≥22%, an outer diameter range of Φ25.4-Φ88.9mm, a wall thickness range of 1.9-6.4mm, a length of more than 61m, and a hardness ≤22HRC, and under a corrosion condition with a pressure ≤0.1MPa, CO2 and a small amount of H2S, the corrosion rate is ≤0.076mm / a. Figure 1 As shown in the figure, the bevel weld high corrosion-resistant continuous pipe prepared by the method has a tensile strength ≥552MPa, a yield strength ≥483MPa, an elongation ≥22%, an outer diameter range of Φ25.4-Φ88.9mm, a wall thickness range of 1.9-6.4mm, a length of more than 61m, and a hardness ≤22HRC, and under a corrosion condition with a pressure ≤0.1MPa, CO2 and a small amount of H2S, the corrosion rate is ≤0.076mm / a.

[0037] Example 2

[0038] The bevel weld high corrosion-resistant continuous pipe prepared by the method has a tensile strength ≥552MPa, a yield strength ≥483MPa, an elongation ≥22%, an outer diameter range of Φ25.4-Φ88.9mm, a wall thickness range of 1.9-6.4mm, a length of more than 61m, and a hardness ≤22HRC, and under a corrosion condition with a pressure ≤0.1MPa, CO2 and a small amount of H2S, the corrosion rate is ≤0.076mm / a.Figure 1 As shown, it includes a first steel pipe 1, a connecting pipe 2 fixedly connected to the first steel pipe 1, and a second steel pipe 3 fixedly connected to the other end of the connecting pipe 2; both ends of the connecting pipe 2 are welded to the first steel pipe 1 and the second steel pipe 3; the first steel pipe 1 and the second steel pipe 3 respectively extend into the connecting pipe 2, and the opposite ends of the first steel pipe 1 and the second steel pipe 3 are respectively welded to the inner wall of the connecting pipe 2; the wall thickness of the first steel pipe 1 is equal to the wall thickness of the second steel pipe 3.

[0039] Example 3

[0040] The high corrosion-resistant continuous pipe with variable wall thickness at the oblique weld seam proposed in this embodiment, such as... Figure 1 As shown, the system includes a first steel pipe 1, a connecting pipe 2 fixedly connected to the first steel pipe 1, and a second steel pipe 3 fixedly connected to the other end of the connecting pipe 2; both ends of the connecting pipe 2 are welded to the first steel pipe 1 and the second steel pipe 3; the first steel pipe 1 and the second steel pipe 3 extend into the connecting pipe 2 respectively, and opposite ends of the first steel pipe 1 and the second steel pipe 3 are welded to the inner wall of the connecting pipe 2 respectively; the wall thickness of the first steel pipe 1 is equal to the wall thickness of the second steel pipe 3; the inner walls of both ends of the connecting pipe 2 are provided with serrated bosses, and the outer walls of both ends of the first steel pipe 1 and the second steel pipe 3 are provided with serrated grooves; the connecting pipe 2 is connected to the first steel pipe 1 and the second steel pipe 3 respectively through the serrated bosses and serrated grooves; a serrated first weld 4 is formed between the connecting pipe 2 and the first steel pipe 1, and the angle of the serrated first weld 4 is 30°-60°.

[0041] Example 4

[0042] The high corrosion-resistant continuous pipe with variable wall thickness at the oblique weld seam proposed in this embodiment, such as... Figure 1 As shown, the system includes a first steel pipe 1, a connecting pipe 2 fixedly connected to the first steel pipe 1, and a second steel pipe 3 fixedly connected to the other end of the connecting pipe 2; both ends of the connecting pipe 2 are welded to the first steel pipe 1 and the second steel pipe 3; the first steel pipe 1 and the second steel pipe 3 extend into the connecting pipe 2 respectively, and opposite ends of the first steel pipe 1 and the second steel pipe 3 are welded to the inner wall of the connecting pipe 2; the wall thickness of the first steel pipe 1 is equal to the wall thickness of the second steel pipe 3; both ends of the connecting pipe 2 have serrated bosses on their inner walls, and both ends of the first steel pipe 1 and the second steel pipe 3 have serrated grooves on their outer walls; the connecting pipe 2 is connected to the first steel pipe 1 and the second steel pipe 3 respectively through the serrated bosses and serrated grooves; a serrated first weld 4 is formed between the connecting pipe 2 and the first steel pipe 1, with an angle of 30°-60°; a serrated second weld 5 is formed between the connecting pipe 2 and the second steel pipe 3, with an angle of 30°-60°.

[0043] Example 5

[0044] The high corrosion-resistant continuous pipe with variable wall thickness at the oblique weld seam proposed in this embodiment, such as... Figure 1As shown, the system includes a first steel pipe 1, a connecting pipe 2 fixedly connected to the first steel pipe 1, and a second steel pipe 3 fixedly connected to the other end of the connecting pipe 2; both ends of the connecting pipe 2 are welded to the first steel pipe 1 and the second steel pipe 3; the first steel pipe 1 and the second steel pipe 3 respectively extend into the connecting pipe 2, and opposite ends of the first steel pipe 1 and the second steel pipe 3 are respectively welded to the inner wall of the connecting pipe 2; the wall thickness of the first steel pipe 1 is equal to the wall thickness of the second steel pipe 3; both ends of the connecting pipe 2 have serrated protrusions on their inner walls; the first steel pipe 1 and the second steel pipe 3... Both ends of the outer wall are provided with serrated grooves. The connecting pipe 2 is connected to the first steel pipe 1 and the second steel pipe 3 respectively through the serrated boss and the serrated groove. A serrated first weld 4 is formed between the connecting pipe 2 and the first steel pipe 1. The angle of the serrated first weld 4 is 30°-60°. A serrated second weld 5 is formed between the connecting pipe 2 and the second steel pipe 3. The angle of the serrated second weld 5 is 30°-60°. The wall thickness of the connecting pipe 2 is 1.5 times the wall thickness of the first steel pipe 1 and the second steel pipe 3.

[0045] Example 6

[0046] The high corrosion-resistant continuous pipe with variable wall thickness at the oblique weld seam proposed in this embodiment, such as... Figure 1 As shown, the system includes a first steel pipe 1, a connecting pipe 2 fixedly connected to the first steel pipe 1, and a second steel pipe 3 fixedly connected to the other end of the connecting pipe 2; both ends of the connecting pipe 2 are welded to the first steel pipe 1 and the second steel pipe 3; the first steel pipe 1 and the second steel pipe 3 extend into the connecting pipe 2, and opposite ends of the first steel pipe 1 and the second steel pipe 3 are welded to the inner wall of the connecting pipe 2; the wall thickness of the first steel pipe 1 is equal to the wall thickness of the second steel pipe 3; the inner walls at both ends of the connecting pipe 2 are provided with serrated bosses, and the outer walls at both ends of the first steel pipe 1 and the second steel pipe 3 are provided with serrated grooves. The connecting pipe 2 is connected to the first steel pipe 1 and the second steel pipe 3 respectively through a serrated boss and a serrated groove. A serrated first weld 4 is formed between the connecting pipe 2 and the first steel pipe 1, with an angle of 30°-60°. A serrated second weld 5 is formed between the connecting pipe 2 and the second steel pipe 3, with an angle of 30°-60°. The wall thickness of the connecting pipe 2 is 1.5 times the wall thickness of the first steel pipe 1 and the second steel pipe 3. The length of the connecting pipe 2 is 1% of the total length of the first steel pipe 1 and the second steel pipe 3.

[0047] Example 7

[0048] The high corrosion-resistant continuous pipe with variable wall thickness at the oblique weld proposed in this embodiment uses molten iron as the main raw material. Alloying elements are added according to the chemical composition of the high corrosion-resistant continuous pipe with variable wall thickness at the oblique weld. The chemical composition is as follows: C: 0.015%; Si: 0.58%; Mn: 1.0%; Cr: 26.7%; Ni: 7.2%; S: 0.01%; P: 0.001%; ​​Mo: 4.3%; N: 0.30%. It is smelted and manufactured into coils with a thickness of 3.0 mm and a length of more than 400 m.

[0049] The prepared coil plate is cut into steel strips of 112 mm by a slitting machine group, and the end of the front and rear steel strips is processed into a 45° bevel, and an I-shaped groove is opened at the 45° bevel. The bevels of the front and rear steel strips are respectively butt welded with the two ends of a steel strip with the same width and the same material and 3.6 mm in thickness and 10 m in length by argon arc welding with argon protection. After the weld cools, the weld surface is polished and cleaned. The weld is heated to 1050°C for solid solution treatment after welding;

[0050] The steel strip side is planed into an I-shaped groove by a milling method, the steel strip is formed by a UO forming method, the formed pipe column is longitudinally welded by laser welding technology, and finally a high corrosion-resistant continuous pipe with a pipe diameter of Φ38.1 mm and a wall thickness of 3.0 mm is welded. After the forming and welding are completed, the continuous pipe is heated to 1020°C by a medium-frequency induction heating method, and then cooled to room temperature after 10 min of heat preservation. Finally, it is wound on a reel to form a disc-shaped high corrosion-resistant continuous pipe with a production length of 3500 m for convenient transportation;

[0051] The main performance of the finally produced high corrosion-resistant continuous pipe is that the yield strength is 708 MPa, the tensile strength is 784 MPa, the elongation reaches 28%, the hardness is 20 HRC, and the corrosion rate is 0.018 mm / a under the corrosion conditions of 10 MPa CO2 partial pressure and 0.08 MPa H2S partial pressure.

[0052] Example 8

[0053] The high corrosion-resistant continuous pipe with variable wall thickness at the inclined weld proposed in this embodiment uses molten iron as the main raw material, and increases alloying elements according to the chemical composition of the high corrosion-resistant continuous pipe with variable wall thickness at the inclined weld. The chemical composition is as follows: C: 0.01%; Si: 0.52%; Mn: 1.3%; Cr: 24.7%; Ni: 6.3%; S: 0.01%; P: 0.002%; Mo: 3.5%; N: 0.29%. The molten iron is smelted and made into a coil plate with a thickness of 4.0 mm and a length of more than 400 m;

[0054] The prepared coil plate is cut into steel strips of 153 mm by a slitting machine group, and the end of the front and rear steel strips is processed into a 45° bevel, and an I-shaped groove is opened at the 45° bevel. The bevels of the front and rear steel strips are respectively butt welded with the two ends of a steel strip with the same width and the same material and 4.5 mm in thickness and 15 m in length by plasma welding. After the weld cools, the weld surface is polished and cleaned. The weld is heated to 1080°C for solid solution treatment after welding;

[0055] The steel strip side is planed into I-shaped groove by milling method, the steel strip is formed by UO forming method, the formed pipe column is longitudinally welded by laser welding technology, and finally a straight seam high corrosion-resistant continuous pipe with a pipe diameter of Φ50.8 mm and a wall thickness of 4.0 mm is welded. After the forming and welding are completed, the whole pipe body of the continuous pipe is heated to 1080℃ by using the intermediate frequency induction heating method, and then the pipe body is kept at 1080℃ for 12 minutes, and then quickly cooled to room temperature. Finally, the pipe body is wound on a reel to form a disc-shaped high corrosion-resistant continuous pipe with a production length of 4200 m, so as to facilitate transportation.

[0056] The main performance of the finally produced high corrosion-resistant continuous pipe is that the yield strength is 690 MPa, the tensile strength is 758 MPa, the elongation rate reaches 27%, the hardness is 19HRC, and the corrosion rate is 0.031 mm / a under the corrosion condition of 10 MPa CO2 partial pressure and 0.08 MPa H2S partial pressure.

Claims

1. A high corrosion resistant continuous pipe with variable wall thickness at the bevel weld characterized in that, The first steel pipe (1) is fixedly connected with a connecting pipe (2), and the other end of the connecting pipe (2) is fixedly connected with a second steel pipe (3); The wall thickness of the connecting pipe (2) is 1.5 times of the wall thickness of the first steel pipe (1) and the second steel pipe (3).

2. The high corrosion resistant continuous pipe with variable wall thickness at the bevel weld of claim 1, wherein, Both ends of the connecting pipe (2) are welded to the first steel pipe (1) and the second steel pipe (3).

3. The high corrosion resistant, continuous pipe with variable wall thickness at the bevel weld of claim 1, wherein, The first steel pipe (1) and the second steel pipe (3) respectively extend into the connecting pipe (2), and the opposite ends of the first steel pipe (1) and the second steel pipe (3) are respectively welded to the inner walls of the connecting pipe (2).

4. The high corrosion resistant, continuous pipe with variable wall thickness at the bevel weld of claim 1, wherein, The wall thickness of the first steel pipe (1) is equal to the wall thickness of the second steel pipe (3).

5. The high corrosion resistant, continuous pipe with variable wall thickness at the bevel weld of claim 1, wherein, The inner walls of both ends of the connecting pipe (2) are provided with sawtooth-shaped bosses, the outer walls of both ends of the first steel pipe (1) and the second steel pipe (3) are provided with sawtooth-shaped grooves, the connecting pipe (2) is connected with the first steel pipe (1) and the second steel pipe (3) through the cooperation of the sawtooth-shaped bosses and the sawtooth-shaped grooves, a sawtooth-shaped first weld (4) is formed between the connecting pipe (2) and the first steel pipe (1), and the angle of the sawtooth-shaped first weld (4) is 30°-60°.

6. The high corrosion resistant, continuous pipe with variable wall thickness at the bevel weld of claim 5, wherein, A sawtooth-shaped second weld (5) is formed between the connecting pipe (2) and the second steel pipe (3), and the angle of the sawtooth-shaped second weld (5) is 30°-60°.

7. The high corrosion resistant, continuous pipe with variable wall thickness at the bevel weld of claim 1, wherein, The length of the connecting pipe (2) is 1% of the total length of the first steel pipe (1) and the second steel pipe (3).

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