Coiled tubing with high chloride ion corrosion resistance and manufacturing method thereof

Abstract

The invention discloses a high chloride ion corrosion resistance continuous pipe which comprises the following components in percentage by mass: less than or equal to 0.02% of C, less than or equal to 0.70% of Si, less than or equal to 1.5% of Mn, 24-27% of Cr, 6-8% of Ni, less than or equal to 0.02% of S, less than or equal to 0.02% of P, 3-5% of Mo, 0.28-0.34% of N and the balance of Fe and inevitable impurities, and the sum of the components is 100%. The invention further discloses a manufacturing method of the continuous pipe with high chloride ion corrosion resistance. The problem that an existing continuous pipe for the high chloride ion corrosion environment is short in service life is solved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas pipeline technology, specifically relating to highly chloride-resistant continuous tubing. This invention also relates to a method for manufacturing highly chloride-resistant continuous tubing. Background Technology

[0002] Coiled tubing (CT) is a new type of oil and gas pipeline material characterized by high strength, high plasticity, and certain corrosion resistance. Single sections can reach lengths of several kilometers. Due to its high efficiency, low cost, wide operating range, and small footprint, coiled tubing technology offers numerous technical and operational advantages. Therefore, it will play an increasingly important role in oil and gas field exploration, development, operation, and production enhancement, and has broad application prospects.

[0003] Continuous tubing operates in harsh environments in oil and gas wells, where the downhole environment contains corrosive gases such as CO2 and H2S, as well as high concentrations of Cl. - Corrosive anions, such as those found in the Klar and Klein blocks, contain corrosive gases like CO2 (around 1%) and H2S, as well as high concentrations of Cl. - Corrosive anions such as (above 50,000 mg / L) and high mineralization (generally above 100,000 mg / L) are present. Under certain temperature and pressure conditions, these substances act on the outer surface of the coiled tubing in ionic form for a long period of time, reacting with Fe or Fe in the tubing. 2+ The reaction occurs and corrodes the pipe body.

[0004] Traditional carbon steel coiled tubing cannot fully meet the production requirements of the complex oil and gas well conditions described above, and corrosion-resistant alloy tubing is usually used as a substitute. Currently, domestic and international corrosion-resistant coiled tubing products are mainly duplex stainless steel and austenitic stainless steel coiled tubing. Among them, 2205 duplex stainless steel coiled tubing exhibits strong corrosion resistance in CO2 and small amounts of H2S corrosive media, while coiled tubing made of austenitic stainless steel has good resistance to CO2 corrosion and pitting corrosion. Both materials have resistance to Cl... - The corrosion resistance of 2205 duplex stainless steel continuous tubing is relatively low. Preliminary tests revealed that it is effective against corrosion in high-Cl concentration environments such as the Kela and Keshen oilfields in the Tarim Oilfield, where concentrations exceed 40,000 mg / L. - Using gas wells as velocity tubing is not feasible for long-term service under the above conditions, and local pitting corrosion may occur under these conditions. Summary of the Invention

[0005] One objective of this invention is to provide a continuous tube with high resistance to chloride ion corrosion, thereby solving the problem of low lifespan of existing continuous tubes used in high chloride ion corrosion environments.

[0006] Another object of the present invention is to provide a method for manufacturing a continuous tube with high resistance to chloride ion corrosion.

[0007] The first technical solution adopted in this invention is: a continuous tube with high resistance to chloride ion corrosion, comprising the following components by mass percentage: C≤0.02%, Si≤0.70%, Mn≤1.5%, Cr: 24%-27%, Ni: 6%-8%, S≤0.02%, P≤0.02%, Mo: 3%-5%, N: 0.28%-0.34%, with the remainder being Fe and unavoidable impurities, and the sum of the above components being 100%.

[0008] The first technical solution of this invention is further characterized in that,

[0009] The continuous tube has a tensile strength ≥669MPa, yield strength ≥620MPa, elongation ≥22%, outer diameter range of Φ25.4~Φ88.9mm, wall thickness range of 1.9~6.4mm, length greater than 61m, and hardness ≤22HRC.

[0010] The second technical solution adopted in this invention is: a method for manufacturing a high chloride ion corrosion resistant continuous tube, wherein the manufacturing of the above-mentioned high chloride ion corrosion resistant continuous tube is carried out according to the following steps:

[0011] Step 1, prepare the rolled plate;

[0012] Step 2: Slitting the rolled plate longitudinally and butt welding the length;

[0013] Step 3, continuous tube forming and welding;

[0014] Step 4: Perform post-weld heat treatment on the longitudinal weld and the entire pipe body;

[0015] Step 5, winding the roll.

[0016] The second technical solution of the present invention is further characterized in that,

[0017] The specific process of step 1 is as follows:

[0018] Step 1.1: Weigh the following components by mass percentage: C≤0.02%, Si≤0.70%, Mn≤1.5%, Cr: 24%-27%, Ni: 6%-8%, S≤0.02%, P≤0.02%, Mo: 3%-5%, N: 0.28%-0.34%, with the remainder being Fe and unavoidable impurities. The sum of the above components shall be 100%.

[0019] Step 1.2: Using molten iron as the main raw material, alloying elements are added sequentially according to the chemical composition in Step 1.1 to obtain the first molten steel;

[0020] Step 1.3: In a vacuum oxygen blowing decarburization refining furnace, the first molten steel is smelted at 1600℃~1700℃ to obtain the second molten steel;

[0021] Step 1.4: Refine the steel in a ladle refining furnace at 1550℃~1650℃. After ladle refining, cast the steel into a continuous casting billet. The billet is cast into a slab with a thickness of 160mm~200mm using continuous casting technology and electromagnetic stirring control, and then cooled under controlled conditions.

[0022] Step 1.5: Rough rolling is carried out at 1260℃-1280℃ using hot charging. The time interval between slab cutting and furnace entry is ≤4h. The slab is then rolled into a hot-rolled plate with a thickness of 2.4mm to 6.35mm at a temperature ≥950℃. After finishing rolling, a front-end centralized laminar flow cooling is used with a cooling rate of 10℃ / s-30℃ / s. Subsequently, the temperature is controlled below 670℃ for coiling. After the steel coil is removed from the line, it is ventilated and cooled to room temperature to produce a coil plate with a length of more than 400 meters.

[0023] The specific process of step 2 is as follows:

[0024] Step 2.1: Cut the coil prepared in Step 1 into steel strips with a width of 50mm to 300mm according to the specifications of continuous pipe using a slitting machine;

[0025] Step 2.2: The steel strip is spliced ​​using a butt joint process. When butt jointing, the ends of the front and rear steel strips are processed into a 45° bevel before butt jointing. The bevel is processed according to the thickness of the plate, and the bevel can be I-shaped, V-shaped or U-shaped.

[0026] Step 2.3: The welding process adopts friction stir welding, gas-protected laser welding, argon arc welding or plasma welding; after welding, the weld is heated to 1020℃-1100℃ for solution treatment.

[0027] The specific process of step 3 is as follows:

[0028] Step 3.1: Based on the outer diameter and wall thickness requirements of the final finished continuous tube, the steel strip side in Step 2.3 is milled into an I-shaped bevel using the edge milling method to precisely control the steel strip width and plate edge perpendicularity.

[0029] Step 3.2: Welding is carried out using high-frequency induction welding, plasma welding or laser welding. Inert gas with a purity of ≥99.99% is used as shielding gas throughout the welding process. Welding results in continuous pipes with a diameter of φ25.4mm~φ88.9mm and a wall thickness of 2.4mm~6.4mm.

[0030] Step 4 is as follows: After the longitudinal welding of the pipe is completed, the pipe is sized by extrusion rollers to apply deformation to the weld. The entire pipe is heated to 1020℃-1100℃ in an inert gas atmosphere by medium frequency induction heating, held for 5min to 20min, and then cooled to room temperature to obtain the finished pipe.

[0031] The specific process of step 5 is as follows: the finished tube after heat treatment in step 4 is wound onto a drum with the corresponding core diameter using a winding machine to continuously produce a continuous tube with a length greater than 61m for transportation and use.

[0032] The beneficial effects of this invention are: the high chloride ion corrosion resistant coiled tubing of this invention has the advantages of high strength, long service life, and resistance to high chloride ion corrosion. While ensuring the strength, plasticity, and fatigue performance of the coiled tubing, it is used as a coiled tubing material in high chloride ion corrosion environments. Through steel strip butt welding, JCO forming, or UO forming; welding employs high-frequency induction welding, plasma welding, or laser welding, solution heat treatment, and other manufacturing processes, duplex stainless steel coiled tubing with high strength, long service life, and excellent corrosion resistance is produced, meeting the requirements for use in high chloride ion corrosion environments in oil and gas fields. Attached Figure Description

[0033] Figure 1 This is a photograph of the microstructure of the high chloride ion corrosion resistant continuous tube base material prepared in Example 1 of the present invention. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0035] The present invention relates to a high chloride ion corrosion resistant continuous tube, comprising the following components by mass percentage: C≤0.02%, Si≤0.70%, Mn≤1.5%, Cr: 24%-27%, Ni: 6%-8%, S≤0.02%, P≤0.02%, Mo: 3%-5%, N: 0.28%-0.34%, with the remainder being Fe and unavoidable impurities, the sum of which is 100%.

[0036] The continuous tube with high resistance to chloride ion corrosion of the present invention has a tensile strength ≥669MPa, a yield strength ≥620MPa, an elongation ≥22%, an outer diameter range of Φ25.4~Φ88.9mm, a wall thickness range of 1.9~6.4mm, a length greater than 61m, and a hardness ≤22HRC.

[0037] In Cl - Under corrosive conditions of water quality with a concentration ≤50000 mg / L, CO2 partial pressure ≤2 MPa, and containing a small amount of H2S (≤0.1 MPa), the corrosion rate is ≤0.076 mm / a.

[0038] The manufacturing method of the high chloride ion corrosion resistant continuous tube of the present invention is carried out according to the following steps:

[0039] Step 1, prepare the rolled plate;

[0040] Step 1.1: Weigh the following components by mass percentage: C≤0.02%, Si≤0.70%, Mn≤1.5%, Cr: 24%-27%, Ni: 6%-8%, S≤0.02%, P≤0.02%, Mo: 3%-5%, N: 0.28%-0.34%, with the remainder being Fe and unavoidable impurities. The sum of the above components shall be 100%.

[0041] Step 1.2: Using molten iron as the main raw material, alloying elements are added sequentially according to the chemical composition in Step 1.1 to obtain the first molten steel;

[0042] Step 1.3: In a vacuum oxygen decarburization (VOD) refining furnace, the first molten steel is smelted at 1600℃~1700℃ to obtain the second molten steel;

[0043] Step 1.4: Refine the steel in a ladle refining furnace (LF) at 1550℃~1650℃. After ladle refining, cast the steel into a continuous casting billet. The billet is cast into a slab with a thickness of 160mm~200mm using continuous casting technology and electromagnetic stirring control, and then cooled under controlled conditions.

[0044] Step 1.5: Rough rolling is carried out at 1260℃-1280℃ using hot charging. The time interval between slab cutting and furnace entry is ≤4h. The slab is then rolled into a hot-rolled plate with a thickness of 2.4mm to 6.35mm at a temperature ≥950℃. After finishing rolling, a front-end centralized laminar flow cooling is used with a cooling rate of 10℃ / s-30℃ / s. Subsequently, the temperature is controlled below 670℃ for coiling. After the steel coil is removed from the line, it is ventilated and cooled to room temperature to produce a coil plate with a length of more than 400 meters.

[0045] Step 2: Slitting the rolled plate longitudinally and butt welding the length;

[0046] Step 2.1: Cut the coil prepared in Step 1 into steel strips with a width of 50mm to 300mm according to the specifications of continuous pipe using a slitting machine;

[0047] Step 2.2: The steel strip is spliced ​​using a butt joint process. When butt jointing, the ends of the front and rear steel strips are processed into a 45° bevel before butt jointing. The bevel is processed according to the thickness of the plate, and the bevel can be I-shaped, V-shaped or U-shaped.

[0048] Step 2.3: The welding process adopts friction stir welding, gas-protected laser welding, argon arc welding or plasma welding; after welding, the weld is heated to 1020℃-1100℃ for solution treatment.

[0049] Step 3, continuous tube forming and welding;

[0050] Step 3.1: Based on the outer diameter and wall thickness requirements of the final finished continuous tube, the steel strip side in Step 2.3 is milled into an I-shaped bevel using the edge milling method to precisely control the steel strip width and plate edge perpendicularity.

[0051] Step 3.2: Welding is carried out using high-frequency induction welding, plasma welding or laser welding. Inert gas with a purity of ≥99.99% is used as shielding gas throughout the welding process. Welding results in continuous pipes with a diameter of φ25.4mm~φ88.9mm and a wall thickness of 2.4mm~6.4mm.

[0052] Step 4: Perform post-weld heat treatment on the longitudinal weld and the entire pipe body;

[0053] After the longitudinal welding of the pipe is completed, the pipe is sized by extrusion rollers to apply deformation to the weld. The entire pipe is heated to 1020℃-1100℃ in an inert gas atmosphere by medium frequency induction heating, held for 5min to 20min, and then cooled to room temperature to obtain the finished pipe.

[0054] Step 5, winding the roll.

[0055] The finished tube after heat treatment in step 4 is wound onto a drum of the corresponding core diameter using a coiler to continuously produce tubes with a length greater than 61m for transportation and use.

[0056] Example 1

[0057] The manufacturing method of the high chloride ion corrosion resistant continuous tube of the present invention is carried out according to the following steps:

[0058] Step 1, prepare the rolled plate;

[0059] Step 1.1 Weigh the following components by mass percentage: C: 0.01%, Si: 0.60%, Mn: 1.0%, Cr: 26.4%, Ni: 7.5%, S: 0.01%, P: 0.003%, Mo: 4%, N: 0.30%, with the remainder being Fe and unavoidable impurities. The sum of the above components is 100%.

[0060] Step 1.2: Using molten iron as the main raw material, alloying elements are added sequentially according to the chemical composition in Step 1.1 to obtain the first molten steel;

[0061] Step 1.3: In a vacuum oxygen blowing decarburization refining furnace, the first molten steel is smelted at 1650℃ to obtain the second molten steel;

[0062] Step 1.4: Refine the steel in a ladle refining furnace at 1650℃. After ladle refining, cast the steel into a continuous casting billet. The billet is then cast into a 200mm thick slab using continuous casting technology and electromagnetic stirring control, followed by controlled cooling.

[0063] Step 1.5: Rough rolling is performed at 1270℃ using hot charging, and final rolling is performed at 980℃ to form a 3mm thick hot-rolled plate. After finishing rolling, a front-end centralized laminar flow cooling is used with a cooling rate of 25℃ / s. Subsequently, the temperature is controlled at 600℃ for coiling. After the steel coil is taken off the line, it is ventilated and cooled to room temperature to produce a coil plate with a length of more than 400 meters.

[0064] Step 2: Slitting the rolled plate longitudinally and butt welding the length;

[0065] Step 2.1: Cut the coil prepared in Step 1 into steel strips with a width of 112mm using a slitting machine according to the specifications of continuous pipe.

[0066] Step 2.2: The steel strip is spliced ​​using a butt joint process, and the ends of the front and rear steel strips are processed into 45° bevels, with an I-shaped bevel cut on the 45° bevel.

[0067] Step 2.3: Use argon arc welding with argon gas protection to butt weld the beveled edges of the two steel strips. After the weld cools, grind and clean the weld surface. After welding, heat the weld to 1050℃ for solution treatment.

[0068] Step 3, continuous tube forming and welding;

[0069] Step 3.1: The steel strip is milled into an I-shaped bevel on the side using the edge milling method, and the steel strip is formed using the UO forming method;

[0070] Step 3.2: The formed tubular column is longitudinally welded using laser welding technology, and finally welded into a continuous tube with a straight seam for high chloride ion corrosion environment with a diameter of Φ38.1mm and a wall thickness of 3.0mm.

[0071] Step 4: Perform post-weld heat treatment on the longitudinal weld and the entire pipe body;

[0072] After the tubing is formed and welded, the entire continuous tube is heated to 1050℃ using medium-frequency induction heating, held at that temperature for 8 minutes, and then rapidly cooled to room temperature to obtain the finished tube.

[0073] Step 5, winding the roll.

[0074] The finished tube after heat treatment in step 4 is wound onto a drum of the corresponding core diameter using a coiler to form a disc-shaped continuous tube with a production length of 4000m for use in high chloride ion corrosion environments, so as to facilitate transportation.

[0075] like Figure 1 As shown, the high chloride ion corrosion resistant continuous tube prepared in Example 1 has a yield strength of 690 MPa, a tensile strength of 774 MPa, an elongation of 28%, and a hardness of 20 HRC. -Under corrosion conditions of water quality with a concentration of 50000 mg / L, a total pressure of 25 MPa, a CO2 partial pressure of 2 MPa, and a H2S partial pressure of 0.08 MPa, the corrosion rate is 0.016 mm / a.

[0076] Example 2

[0077] The manufacturing method of the high chloride ion corrosion resistant continuous tube of the present invention is carried out according to the following steps:

[0078] Step 1, prepare the rolled plate;

[0079] Step 1.1 Weigh the following components by mass percentage: C: 0.01%, Si: 0.52%, Mn: 1.1%, Cr: 24.4%, Ni: 6.4%, S: 0.01%, P: 0.002%, Mo: 3.7%, N: 0.31%, with the remainder being Fe and unavoidable impurities. The sum of the above components is 100%.

[0080] Step 1.2: Using molten iron as the main raw material, alloying elements are added sequentially according to the chemical composition in Step 1.1 to obtain the first molten steel;

[0081] Step 1.3: In a vacuum oxygen blowing decarburization refining furnace, the first molten steel is smelted at 1640℃ to obtain the second molten steel;

[0082] Step 1.4: Refine the steel in a ladle refining furnace at 1580℃. After ladle refining, cast the steel into a continuous casting billet. Use continuous casting technology and apply electromagnetic stirring control to cast the billet into a 200mm thick slab and control cooling.

[0083] Step 1.5: Rough rolling is performed at 1265℃ using hot charging, and final rolling is performed at 975℃ to form a 4mm thick hot-rolled plate. After finishing rolling, a front-end centralized laminar flow cooling is used with a cooling rate of 25℃ / s. Subsequently, the temperature is controlled at 580℃ for coiling. After the steel coil is taken off the line, it is ventilated and cooled to room temperature to produce a coil plate with a length of more than 400 meters.

[0084] Step 2: Slitting the rolled plate longitudinally and butt welding the length;

[0085] Step 2.1: Cut the coil prepared in Step 1 into steel strips with a width of 153mm using a slitting machine according to the specifications of continuous pipe.

[0086] Step 2.2: The steel strip is spliced ​​using a butt joint process, and the ends of the front and rear steel strips are processed into 45° bevels, with an I-shaped bevel cut on the 45° bevel.

[0087] Step 2.3: Butt weld the two steel strips at their bevels using argon-protected plasma welding. After the weld cools, grind and clean the weld surface. After welding, heat the weld to 1080℃ for solution treatment.

[0088] Step 3, continuous tube forming and welding;

[0089] Step 3.1: The steel strip is milled into an I-shaped bevel on the side using the edge milling method, and the steel strip is formed using the UO forming method;

[0090] Step 3.2: The formed tubular column is longitudinally welded using laser welding technology, and finally welded into a continuous tube with a diameter of Φ50.8mm and a wall thickness of 4.0mm.

[0091] Step 4: Perform post-weld heat treatment on the longitudinal weld and the entire pipe body;

[0092] After the tubing is formed and welded, the entire continuous tube is heated to 1080℃ using medium-frequency induction heating, held for 10 minutes, and then rapidly cooled to room temperature to obtain the finished tube.

[0093] Step 5, winding the roll.

[0094] The finished tube after heat treatment in step 4 is wound onto a drum of the corresponding core diameter using a coiler to form a disc-shaped continuous tube with a production length of 4000m for use in high chloride ion corrosion environments, so as to facilitate transportation.

[0095] The high chloride ion corrosion resistant continuous tube prepared in Example 2 has a yield strength of 639 MPa, a tensile strength of 718 MPa, an elongation of 26%, and a hardness of 19 HRC. - Under corrosion conditions of water quality with a concentration of 50000 mg / L, a total pressure of 25 MPa, a CO2 partial pressure of 2 MPa, and a H2S partial pressure of 0.08 MPa, the corrosion rate is 0.039 mm / a.

[0096] Example 3

[0097] The manufacturing method of the high chloride ion corrosion resistant continuous tube of the present invention is carried out according to the following steps:

[0098] Step 1, prepare the rolled plate;

[0099] Step 1.1 Weigh the following components by mass percentage: C: 0.02%, Si: 0.70%, Mn: 1.5%, Cr: 24%, Ni: 6%, S: 0.02%, P: 0.02%, Mo: 3%, N: 0.28%, with the remainder being Fe and unavoidable impurities. The sum of the above components is 100%.

[0100] Step 1.2: Using molten iron as the main raw material, alloying elements are added sequentially according to the chemical composition in Step 1.1 to obtain the first molten steel;

[0101] Step 1.3: In a vacuum oxygen blowing decarburization refining furnace, the first molten steel is smelted at 1600℃ to obtain the second molten steel;

[0102] Step 1.4: Refine the steel in a ladle refining furnace at 1550℃. After ladle refining, cast the steel into a continuous casting billet. The billet is then cast into a 160mm thick slab using continuous casting technology and electromagnetic stirring control, followed by controlled cooling.

[0103] Step 1.5: Rough rolling is performed at 1260℃ using hot charging, and the hot-rolled plate is finally rolled to a thickness of 2.4mm at a temperature of 950℃. After finishing rolling, the front-end centralized laminar flow cooling is used at a cooling rate of 10℃ / s. Then the temperature is controlled at 670℃ for coiling. After the steel coil is taken off the line, it is ventilated and cooled to room temperature to produce a coil plate with a length of more than 400 meters.

[0104] Step 2: Slitting the rolled plate longitudinally and butt welding the length;

[0105] Step 2.1: Cut the coil prepared in Step 1 into steel strips with a width of 50mm using a slitting machine according to the specifications of continuous pipe.

[0106] Step 2.2: The steel strip is spliced ​​using a butt joint process. When splicing, the ends of the front and rear steel strips are processed into a 45° bevel before being joined together. The bevel is V-shaped.

[0107] Step 2.3: The welding process adopts friction stir welding, and the weld is heated to 1020℃ for solution treatment after welding.

[0108] Step 3, continuous tube forming and welding;

[0109] Step 3.1: Based on the outer diameter and wall thickness requirements of the final finished continuous tube, the steel strip side in Step 2.3 is milled into an I-shaped bevel using the edge milling method to precisely control the steel strip width and plate edge perpendicularity.

[0110] Step 3.2: Plasma welding is used to weld a continuous pipe with a diameter of φ25.4mm and a wall thickness of 2.4mm.

[0111] Step 4: Perform post-weld heat treatment on the longitudinal weld and the entire pipe body;

[0112] Step 4.1: After the longitudinal welding of the pipe is completed, the pipe is sized using an extrusion roller to apply deformation to the weld. The entire pipe is then heated to 1020℃ in an inert gas atmosphere using medium-frequency induction heating, held for 5 minutes, and cooled to room temperature to obtain the finished pipe.

[0113] Step 5, winding the roll.

[0114] The finished tube after heat treatment in step 4 is wound onto a drum of the corresponding core diameter using a coiler to form a disc-shaped continuous tube with a production length of 4000m for use in high chloride ion corrosion environments, so as to facilitate transportation.

[0115] Example 4

[0116] The manufacturing method of the high chloride ion corrosion resistant continuous tube of the present invention is carried out according to the following steps:

[0117] Step 1, prepare the rolled plate;

[0118] Step 1.1 Weigh the following components by mass percentage: C: 0.02%, Si: 0.58%, Mn: 1.4%, Cr: 27%, Ni: 8%, S: 0.02%, P: 0.01%, Mo: 5%, N: 0.34%, with the remainder being Fe and unavoidable impurities. The sum of the above components is 100%.

[0119] Step 1.2: Using molten iron as the main raw material, alloying elements are added sequentially according to the chemical composition in Step 1.1 to obtain the first molten steel;

[0120] Step 1.3: In a vacuum oxygen blowing decarburization refining furnace, the first molten steel is smelted at 1700℃ to obtain the second molten steel;

[0121] Step 1.4: Refine the steel in a ladle refining furnace at 1650℃. After ladle refining, cast the steel into a continuous casting billet. The billet is then cast into a 160mm thick slab using continuous casting technology and electromagnetic stirring control, followed by controlled cooling.

[0122] Step 1.5: Rough rolling is performed at 1280℃ using hot charging, and the hot-rolled plate is finally rolled to a thickness of 6.35mm at a temperature of 960℃. After finishing rolling, a front-end centralized laminar flow cooling is used with a cooling rate of 30℃ / s. Subsequently, the temperature is controlled at 660℃ for coiling. After the steel coil is taken off the line, it is ventilated and cooled to room temperature to produce a coil plate with a length of more than 400 meters.

[0123] Step 2: Slitting the rolled plate longitudinally and butt welding the length;

[0124] Step 2.1: Cut the coil prepared in Step 1 into steel strips with a width of 300mm using a slitting machine according to the specifications of continuous pipe.

[0125] Step 2.2: The steel strip is spliced ​​using a butt joint process. During the butt joint, the ends of the front and rear steel strips are processed into a 45° bevel before being joined together. The bevel is U-shaped.

[0126] Step 2.3: The welding process uses plasma welding; after welding, the weld is heated to 1100℃ for solution treatment.

[0127] Step 3, continuous tube forming and welding;

[0128] Step 3.1: Based on the outer diameter and wall thickness requirements of the final finished continuous tube, the steel strip side in Step 2.3 is milled into an I-shaped bevel using the edge milling method to precisely control the steel strip width and plate edge perpendicularity.

[0129] Step 3.2: Laser welding is used, and an inert gas with a purity of ≥99.99% is used as a protective gas throughout the welding process; the welded pipe is a continuous pipe with a diameter of φ88.9mm and a wall thickness of 6.4mm.

[0130] Step 4: Perform post-weld heat treatment on the longitudinal weld and the entire pipe body;

[0131] Step 4.1: After the longitudinal welding of the pipe is completed, the pipe is sized by extrusion rollers to apply deformation to the weld. The entire pipe is heated to 1100℃ in an inert gas atmosphere by medium frequency induction heating, held for 20 minutes, and then cooled to room temperature to obtain the finished pipe.

[0132] Step 5, winding the roll.

[0133] The finished tube after heat treatment in step 4 is wound onto a drum of the corresponding core diameter using a coiler to form a disc-shaped continuous tube with a production length of 4000m for use in high chloride ion corrosion environments, so as to facilitate transportation.

[0134] The continuous tubing for high chloride ion corrosion environments prepared in the above four embodiments is equipped with alloying elements according to the composition requirements. The mass percentage of elements Cr and Ni in the composition is relatively high. The prepared continuous tubing not only meets the strength, plasticity, and fatigue performance requirements of conventional continuous tubing, but also has the ability to resist high chloride ions. It can meet the needs of tubing operation in high chloride ion environments in oil fields, greatly improve the corrosion resistance of the tubing in high chloride ion environments, reduce the reduction of tubing wall thickness, and thus improve its service life.

Claims

1. A high-chloride-corrosion-resistant continuous tube, characterized by, The following components are included by mass percentage: C≤0.02%, Si≤0.70%, Mn≤1.5%, Cr: 24%-27%, Ni: 6%-8%, S≤0.02%, P≤0.02%, Mo: 3%-5%, N: 0.28%-0.34%, the rest being Fe and inevitable impurities, and the sum of the above components being 100%.

2. The high-chloride-corrosion-resistant continuous tube of claim 1, wherein, The continuous pipe has a tensile strength ≥669 MPa, a yield strength ≥620 MPa, an elongation ≥22%, an outer diameter ranging from Φ25.4 to Φ88.9 mm, a wall thickness ranging from 1.9 to 6.4 mm, a length greater than 61 m, and a hardness ≤22 HRC.

3. A method of manufacturing a high-chloride-corrosion-resistant continuous tube, the high-chloride-corrosion-resistant continuous tube according to claim 2, characterized by, The implementation is specifically performed according to the following steps: Step 1, preparing a coiled plate; Step 2, coiled plate longitudinal cutting and butt welding; Step 3, continuous pipe forming and welding; Step 4, post-welding heat treatment on the longitudinal weld and the whole pipe body; Step 5, coiled plate winding.

4. The method of manufacturing a high-chloride-corrosion-resistant continuous tube according to claim 3, wherein The specific process of Step 1 is as follows: Step 1.1, the following components are included by mass percentage: C≤0.02%, Si≤0.70%, Mn≤1.5%, Cr: 24%-27%, Ni: 6%-8%, S≤0.02%, P≤0.02%, Mo: 3%-5%, N: 0.28%-0.34%, the rest being Fe and inevitable impurities, and the sum of the above components being 100%; Step 1.2, molten iron is used as the main raw material, and alloying elements are added according to the chemical components in Step 1.1 to obtain first molten steel; Step 1.3, the first molten steel is smelted at 1600℃-1700℃ in a vacuum oxygen-decarburization refining furnace to obtain second molten steel; Step 1.4, refining is performed at 1550℃-1650℃ in a ladle refining furnace, and after ladle refining, the continuous casting billet is poured into a cast slab with a thickness of 160mm-200mm by using continuous casting technology and applying electromagnetic stirring for controlled cooling; Step 1.5, rough rolling is performed at 1260℃-1280℃, hot charging is used for rolling, the cast slab is cut to an interval of ≤4h from charging time, and final rolling is performed at a temperature ≥950℃ to form a hot-rolled plate with a thickness of 2.4mm-6.35mm, after finish rolling, front-stage concentrated laminar cooling is used at a cooling speed of 10℃ / s-30℃ / s, and then the temperature is controlled below 670℃ for coiling, after the steel coil is discharged, it is cooled to room temperature by ventilation, and a coiled plate with a length exceeding 400m is prepared.

5. The method of manufacturing a high-chloride-corrosion-resistant continuous tube according to claim 4, wherein The specific process of Step 2 is as follows: Step 2.1, the coiled plate prepared in Step 1 is cut into steel strips with a width of 50mm-300mm by a longitudinal cutting machine according to the specifications of the continuous pipe; Step 2.2, butt joint technology is used for steel strip jointing, and the end parts of the front and rear steel strips are machined into 45° bevels before butt jointing; the bevels are machined according to the thickness of the plate, and the bevels are I-shaped, V-shaped or U-shaped; Step 2.3, the welding process uses 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.

6. The method of manufacturing a high-chloride-corrosion-resistant continuous tube according to claim 5, wherein The specific process of Step 3 is as follows: Step 3.1, according to the outer diameter and wall thickness requirements of the final product continuous tube, the steel strip side in step 2.3 is planed into I-shaped groove by milling method, and the steel strip width and plate edge perpendicularity are accurately controlled; Step 3.2, welding adopts high-frequency induction welding, plasma welding or laser welding, and inert gas with purity ≥ 99.99% is used as protective gas during the whole welding process; the welded tube has a diameter of φ25.4mm-φ88.9mm and a wall thickness of 2.4mm-6.4mm.

7. The method of manufacturing a high-chloride-corrosion-resistant continuous tube according to claim 6, wherein The specific process of step 4 is as follows: after the longitudinal welding of the pipe material is completed, the pipe material is subjected to sizing by using an extrusion roller to apply a deformation amount to the weld, and the whole tube body is heated to 1020℃-1100℃ under an inert gas atmosphere by using a medium-frequency induction heating method, and is kept for 5min-20min, and is cooled to room temperature, to obtain the finished pipe.

8. The method of manufacturing a high-chloride-corrosion-resistant continuous tube according to claim 7, wherein The specific process of step 5 is as follows: the finished pipe after heat treatment in step 4 is wound onto a corresponding core diameter winding drum by a winding machine, and a continuous tube with a continuous production length of greater than 61m is produced, so as to facilitate transportation and use.

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