A gas lift operation dual metal composite coiled tubing and a manufacturing method thereof

Abstract

A kind of gas lift operation with bimetallic composite coiled tubing, comprising: base layer, set in the base layer outer complex layer, the base layer and complex layer are welded to form pipe body;The pipe body outer diameter is Φ25.4~50.8mm, single length is 1000~2000m;The base layer material is low carbon steel, and the thickness is 2~3mm;The complex layer material is Inconel625 nickel-based alloy, and the thickness is 1~1.5mm.The gas lift operation with bimetallic composite coiled tubing is manufactured, solves the problem of poor corrosion resistance of existing carbon steel continuous tube, to provide support for the development of acid oil and gas field.

Description

Technical Field

[0001] This invention belongs to the field of coiled tubing technology and relates to a bimetallic composite coiled tubing for air lift operations and its manufacturing method. Background Technology

[0002] Coiled tubing is a type of tubing ranging from hundreds to thousands of meters in length. It is typically made of low-carbon microalloyed steel in HFW or laser-welded form and is transported and used while wound on a large-diameter drum. In the oil and gas industry, it is widely used in well workover, drilling, completion, logging, and production enhancement operations. During operation, the tubing on the drum can be repeatedly wound and unwound for reuse. However, in the development of highly acidic oil and gas fields containing corrosive media such as H2S, CO2, and Cl-, ordinary coiled tubing not only suffers from high-rate weight loss corrosion and localized corrosion, but also experiences operational failures, hindering the development of acidic oil and gas fields.

[0003] Therefore, it is necessary to develop a continuous tubing that can solve the above problems. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for manufacturing bimetallic composite coiled tubing for gas lift operations. The coiled tubing manufactured using this method solves the problem of poor corrosion resistance of existing carbon steel coiled tubing, thereby providing support for the development of acidic oil and gas fields.

[0005] The present invention is achieved through the following technical solution: a bimetallic composite continuous tubing for air lift operations is provided, comprising: a base layer and a cladding layer disposed outside the base layer, wherein the base layer and the cladding layer are welded together to form a tubing body; The outer diameter of the tube is Φ25.4~50.8mm, and the length of a single tube is 1000~2000m; The base layer is made of low-carbon steel with a thickness of 2-3 mm; The cladding material is Inconel 625 nickel-based alloy, with a thickness of 1–1.5 mm.

[0006] Specifically, the chemical composition of the base layer, calculated by mass percentage, includes the following components: C 0.08–0.10%, Si 0.10–0.24%, Mn 0.8–1.0%, P≦0.004%, S≦0.004%, Cr 0.80–1.2%, Mo 0.12–0.16%, Ni 0.18–0.22%, Ti 0.02–0.03%, Al 0.02–0.03%, with the remainder being Fe and unavoidable impurities.

[0007] Specifically, a plug and a one-way positive pressure valve are installed at the front end of the pipe body. The plug is made of Inconel 625 nickel-based alloy. A threaded through hole is opened at the end of the plug facing the pipe body. The one-way positive pressure valve is threadedly connected to the plug through the threaded through hole.

[0008] Specifically, a union is welded to the tail end of the tube.

[0009] This invention also provides a method for manufacturing bimetallic composite coiled tubing for gas lift operations, comprising the following steps: S1 The base layer and the cladding layer are bonded together by explosive welding to obtain a bimetallic composite coil. The base layer is made of low carbon steel and the cladding layer is made of Inconel 625 nickel-based alloy. S2 The bimetallic composite coil obtained in S1 is cut into steel strips according to the specifications of continuous tubing using a slitting machine, and the ends of the steel strips are spliced ​​together according to the required length. S3 According to the outer diameter and wall thickness requirements of the final bimetallic composite coiled tubing, the two ends of the extended steel strip are processed into I-shaped bevels by milling, and the steel strip is rolled into a tubular shape by roller forming method. The longitudinal weld is welded by laser filler wire process. The welding wire is ERNiCrMo-3 nickel-based alloy welding wire. The bimetallic composite coiled tubing obtained after welding is wound onto a drum I with an appropriate core diameter. S4 transports the bimetallic composite continuous tubing manufactured in S3 to the heat treatment unit, and uses a scraper to scrape a V-shaped groove with a depth of 0.8-1 mm and an angle of 60° along the longitudinal weld surface. Next, a cladding weld is performed to achieve the cladding of the bimetallic composite continuous tubing. In this invention, the depth of the V-shaped groove is set to 0.8-1 mm, which can control the welding penetration of the cladding nickel-based alloy layer to not exceed the thickness of the cladding nickel-based alloy layer, while ensuring that the chemical composition of the weld metal is closer to that of the cladding nickel-based alloy material, thereby improving the corrosion resistance of the weld joint. At the same time, the angle of the V-shaped groove is set to 60°, so that the welded cladding layer is wider than the base weld, ensuring that the base weld is not exposed on the outer surface of the tubing and causes corrosion.

[0010] S5 has a union welded to the tail end of the bimetallic composite continuous tubing and connected to the water injection pump, and is then subjected to quenching and tempering heat treatment in sequence. S6 inserts the plug equipped with a one-way positive pressure valve into the front end of the bimetallic composite coiled tubing, and uses argon arc welding to weld it to the end of the bimetallic composite coiled tubing at the external bevel position, thus completing the processing of the bimetallic composite coiled tubing for air lift operations.

[0011] Specifically, in S2, when splicing the steel strips at both ends, the ends of the two steel strips to be spliced ​​together need to be cut at a 45° angle to the length of the steel strips using a shearing machine. Next, the two steel strips are welded using plasma welding with ERNiCrMo-3 nickel-based alloy welding wire. After welding, the weld reinforcement is ground to be flush with the base material. In this invention, since the butt welds of the steel strips are spirally distributed in the pipe body after pipe forming, in S2, cutting the ends of the two steel strips to be spliced ​​together at a 45° angle to the length of the steel strips using a shearing machine can effectively reduce stress concentration at the weld when the weld is under stress during operation, thereby improving the safety of the welding operation.

[0012] Specifically, before the cladding welding in S4, a pressure roller is used to press a 1mm diameter ERNiCrMo-3 nickel-based alloy welding wire into the bottom of the V-groove. Then, two plasma welding guns, distributed at 30° intervals and spaced 300mm apart, are used to weld the cladding weld. The weld penetration depth is controlled between 0.8 and 1mm. In this step, the welding current is 100A, the voltage is 22V, the welding speed is 480mm / min, the ion gas flow rate is 2.8L / min, the shielding gas flow rate is 15L / min, the gas type is Ar+5%H2, and the weld cladding metal thickness is 1~1.5mm.

[0013] Specifically, S5 is implemented according to the following scheme: A bimetallic composite continuous oil tube is heated to 950°C in an inert atmosphere-protected medium-frequency heat treatment furnace. Simultaneously, water is injected into the tube for cooling via a water pump, performing a quenching heat treatment. The bimetallic composite continuous oil tube is then wound onto drum II. After quenching, the heat treatment unit is reversed, and the tube body is heated to 550°C under an inert atmosphere-protected environment, followed by air cooling for tempering heat treatment. The bimetallic composite continuous oil tube is then wound onto drum I. The medium-frequency induction heating coil of the medium-frequency heat treatment furnace is 150mm long, and the internal circulating water flow rate is 100m³ / h during water injection for cooling. 3 / h.

[0014] Specifically, the welding processes for S5 and S6 are the same, both using ERNiCrMo-3 nickel-based alloy welding wire, welding current of 75A, voltage of 16V, welding speed of 4.5cm / min, and shielding gas of argon with a gas flow rate of 12L / min.

[0015] During operation, the bimetallic composite coiled tubing manufactured by this invention is used for gas lift operations. The front end of the tubing string is lowered into the water layer in the well, and the rear end of the tubing string is connected to a nitrogen supply vehicle via a union. The nitrogen supply vehicle injects nitrogen into the tubing string. When the nitrogen injection pressure reaches a certain value, the one-way positive pressure valve opens and high-pressure nitrogen is injected into the well through the through hole in the plug. The nitrogen carries the bottom hole fluid out through the annulus between the bimetallic composite coiled tubing and the production tubing to perform the gas lift operation.

[0016] Compared with the prior art, the present invention provides a bimetallic composite coiled tubing for air lift operations, which has the following advantages: 1. This invention places a clad nickel-based alloy on the outer layer of the tubing, which effectively prevents the corrosion of the tubing by corrosive media such as hydrogen sulfide in the working environment; and places a base low-carbon steel layer on the inner layer of the tubing, and installs a plug and a one-way positive pressure valve at the front end, which effectively prevents corrosive media from entering the interior of the coiled tubing and corroding the inner low-carbon steel layer. 2. Adding Cr element with a mass fraction of 0.80-1.2% to the low carbon steel alloy of the base layer can effectively improve hardenability and ensure the mechanical properties of the tube. Adding Al element with a mass fraction of 0.02-0.03% can prevent the generation of porosity during laser welding of nickel-based alloys. 3. The welding joint form using a 60° V-groove and a pre-installed 1mm diameter nickel-based alloy welding wire at the root solves the process problem that the thin steel strip cannot reduce the dilution rate of the weld metal elements by welding a transition layer, effectively ensuring the corrosion resistance of the cladding weld. 4. During the tube quenching heat treatment process, water is injected into the tube for cooling. Compared with the traditional external spray cooling, this solves the oxidation problem of the cladding nickel-based alloy layer and also improves the hardenability of the inner low-carbon steel layer, ensuring the mechanical properties of the base metal. 5. Laser filler wire welding is used for the formed bimetallic composite continuous tubing, which has the advantages of high welding efficiency and small heat-affected zone, and prevents cracks caused by overheating during the welding of nickel-based alloys. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of a bimetallic composite coiled tubing for air lift operations according to the present invention; Figure 2 This is a schematic diagram of a bimetallic composite continuous tubing string structure for air lift operations according to the present invention; Figure 3 This is a schematic diagram of the multilayer welding and heat treatment unit in the manufacturing process of a bimetallic composite continuous tubing for air lift operations according to the present invention. Figure 4 This is a diagram of the bevel structure for multilayer welding during the fabrication process of a bimetallic composite continuous tubing for air lift operations according to the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings.

[0019] To address the problems of poor corrosion resistance of existing low-carbon microalloy steel coiled tubing and high cost of corrosion-resistant alloy coiled tubing in gas lift operations of highly acidic oil and gas wells exposed to high H2S, CO2, and Cl- corrosive media, this invention provides a bimetallic composite coiled tubing for gas lift and its preparation method.

[0020] Please see Figure 1 , Figure 1 A cross-sectional view of a bimetallic composite coiled tubing for air lift operations prepared for the invention. The composite coiled tubing includes: a base layer 101 and a cladding layer 102 disposed outside the base layer 101. The base layer 101 and the cladding layer 102 are welded together to form a tubing body (i.e., bimetallic composite coiled tubing 1). The outer diameter of the tube is Φ25.4~50.8mm, and the length of a single tube is 1000~2000m; The base layer 101 is made of low-carbon steel with a thickness of 2-3 mm. Its chemical composition, calculated by mass percentage, includes the following components: C 0.08~0.10%, Si 0.10~0.24%, Mn 0.8~1.0%, P≦0.004%, S≦0.004%, Cr 0.80~1.2%, Mo 0.12~0.16%, Ni 0.18~0.22%, Ti 0.02~0.03%, Al 0.02~0.03%, with the remainder being Fe and unavoidable impurities; The 102 layer is made of Inconel 625 nickel-based alloy and has a thickness of 1 to 1.5 mm.

[0021] Please see Figure 2 , Figure 2 This is a schematic diagram of the bimetallic composite coiled tubing string structure for air lift operations. The bimetallic composite coiled tubing for air lift operations includes: a plug 4 welded to the front end of the bimetallic composite coiled tubing 1, the upper end of the plug 4 being inserted into the interior of the bimetallic composite coiled tubing 1 and connected to the bimetallic composite coiled tubing 1 through a weld 3, a through hole 5 being opened inside the plug 4, and an internal thread being machined on its upper part and connected to a one-way positive pressure valve 2 through the thread, and a union 7 being welded to the tail end of the bimetallic composite coiled tubing 1. The entire bimetallic composite coiled tubing 1 is wound on a drum 6. Example 1

[0022] This invention provides a bimetallic composite coiled tubing for air lift operations, comprising the following steps: Preparation of S1 bimetallic composite coil The base layer and the cladding layer are combined by explosive welding and rolling to obtain a bimetallic composite coil.

[0023] S2 Bimetallic Composite Coil Slitting and Splicing The bimetallic composite coil prepared by S1 is cut into steel strips of about 500m in length according to the specifications of continuous tubing. The ends of the steel strips are spliced ​​together according to the required tubing length. During splicing, the ends of the two steel strips to be spliced ​​together are cut into bevels at 45° with the length direction of the steel strips by a shearing machine. Then, plasma welding is carried out, and the welding wire used is ERNiCrMo-3 nickel-based alloy. After welding, the weld reinforcement is ground to be flush with the base material.

[0024] S3 forming and first step welding Based on the final outer diameter and wall thickness requirements of the bimetallic composite coiled tubing, the two ends of the extended steel strip are milled into I-shaped bevels. The steel strip is then rolled into a tubular shape using a roller forming method. The longitudinal weld is then performed using a laser filler wire process, with ERNiCrMo-3 nickel-based alloy welding wire used, thus producing the bimetallic composite coiled tubing. Simultaneously, the bimetallic composite coiled tubing is wound onto a drum I with an appropriate core diameter.

[0025] S4 cladding welding Please see Figure 3 , Figure 3 This is a schematic diagram of a multi-layer welding and heat treatment unit, which includes: a heat treatment unit consisting of a water injection pump 8, a drum I, a delivery roller 9, a scraper 10, a pressure roller 12, a plasma welding torch 13, a plasma welding torch 14, a medium-frequency heat treatment furnace 15, and a drum II; the bimetallic composite continuous oil pipe made of S3 is moved to the heat treatment unit, and the bimetallic composite continuous oil pipe is transported to the heat treatment unit by the delivery roller 9. The scraper 10 scrapes a V-shaped groove with a depth of 0.8-1mm and an angle of 60° along the length direction of the longitudinal weld seam of S3; then, the pressure roller 12 presses the 1mm diameter ERNiCrMo-3 nickel-based alloy welding wire 11 into the bottom of the V-groove; next, two plasma welding torches 13 and 14 are distributed at 30° on both sides of the central axis of the groove, with a spacing of 300mm, to weld the multi-layer weld seam, and the weld penetration depth is controlled within the range of 1-1.5mm.

[0026] S5 heat treatment A union is welded to the tail end of the bimetallic composite continuous tubing and connected to a water injection pump 1. The bimetallic composite continuous tubing is heated to 950°C in an inert atmosphere using a medium-frequency heat treatment furnace 15. Simultaneously, water is injected into the bimetallic composite continuous tubing 1 through a water injection pump 8 for quenching heat treatment. At the same time, the quenched bimetallic composite continuous tubing is wound onto a reel II. After the quenching heat treatment is completed, the heat treatment unit is reversed, and the tube body is heated to 550°C in an inert atmosphere using a medium-frequency heating furnace and then air-cooled for tempering heat treatment. The bimetallic composite continuous tubing is then wound onto a reel I.

[0027] S6 Bimetallic Composite Coiled Tubing End Plug and Union Welding The plug 4, equipped with a one-way positive pressure valve, is inserted into the front end of the bimetallic composite coiled tubing and welded to the coiled tubing end at the external bevel position using argon arc welding. The welding wire is ERNiCrMo-3 nickel-based alloy welding wire, the welding current is 75A, the voltage is 16V, the welding speed is 4.5cm / min, the shielding gas is argon, and the gas flow rate is 12L / min. Subsequently, a union is welded to the tail end of the bimetallic composite coiled tubing, and its welding process is the same as that of the plug.

[0028] The bimetallic composite coiled tubing provided by this invention, during operation, involves lowering the front end of the tubing into the well fluid layer using a coiled tubing installation vehicle. The rear end of the tubing is connected to a nitrogen installation vehicle via a union, through which nitrogen gas at a certain pressure is injected into the tubing string. When the nitrogen injection pressure reaches the opening pressure of the one-way positive pressure valve (e.g., 12 MPa), the one-way positive pressure valve opens, and high-pressure nitrogen gas is injected into the well through a through-hole in the plug. The high-pressure nitrogen gas then discharges the bottomhole fluid through the annulus between the bimetallic composite coiled tubing and the production tubing, achieving a gas lift operation.

Claims

1. A method for manufacturing a bimetallic composite coiled tubing for air lift operations, characterized in that, The bimetallic composite coiled tubing for air lift operations includes a base layer and a cladding layer located outside the base layer. The base layer and the cladding layer are welded together to form a tubing body. The outer diameter of the tubing body is Φ25.4~50.8mm, and the length of a single tube is 1000~2000m. The base layer is made of low carbon steel and has a thickness of 2~3mm. The cladding material is Inconel 625 nickel-based alloy with a thickness of 1-1.5 mm. The chemical composition of the base layer, calculated by mass percentage, includes the following components: C 0.08-0.10%, Si 0.10-0.24%, Mn 0.8-1.0%, P≦0.004%, S≦0.004%, Cr 0.80-1.2%, Mo 0.12-0.16%, Ni 0.18-0.22%, Ti 0.02-0.03%, Al 0.02-0.03%, with the remainder being Fe and unavoidable impurities. A plug and a one-way positive pressure valve are installed at the front end of the tube. The plug is made of Inconel 625 nickel-based alloy, and a threaded through hole is opened at the end of the plug facing the tube. The one-way positive pressure valve is threadedly connected to the plug through the threaded through hole. The manufacturing method includes the following steps: S1 combines the base layer and the cladding layer by explosive welding to obtain a bimetallic composite coil. S2 uses a slitting machine to cut bimetallic composite coils into steel strips, and splices the ends of the steel strips according to the required length. S3 uses a roller forming method to roll the steel strip into a tubular shape, and uses a laser wire filling process to weld the longitudinal weld seam. After welding, the bimetallic composite continuous tubing is wound onto drum I. In step S4, the bimetallic composite continuous tubing manufactured in step S3 is transported to the heat treatment unit. A V-shaped groove with a depth of 0.8–1 mm and an angle of 60° is scraped out on the longitudinal weld surface along the length direction using a scraper. Next, a cladding weld is performed to achieve the cladding weld of the bimetallic composite continuous tubing. Before the cladding weld in step S4, a 1 mm diameter ERNiCrMo-3 nickel-based alloy welding wire is pressed into the bottom of the V-groove using a pressure roller. Then, two plasma welding guns are used to weld the cladding weld at a 30° angle on both sides of the central axis of the V-groove, with a spacing of 300 mm. The weld penetration depth is controlled at 0.8–1 mm. In this step, the welding current is 100 A, the voltage is 22 V, the welding speed is 480 mm / min, the ion gas flow rate is 2.8 L / min, the shielding gas flow rate is 15 L / min, the gas type is Ar + 5% H2, and the weld cladding metal thickness is 1–1.5 mm. S5 involves welding a union to the tail end of a bimetallic composite continuous tubing and connecting it to a water injection pump, followed by quenching and tempering heat treatments. S5 is specifically implemented according to the following scheme: A bimetallic composite continuous oil tube is heated to 950°C in an inert atmosphere-protected medium-frequency heat treatment furnace. Simultaneously, water is injected into the tube for cooling via a water pump, performing a quenching heat treatment. The bimetallic composite continuous oil tube is then wound onto drum II. After quenching, the heat treatment unit is reversed, and the tube body is heated to 550°C under an inert atmosphere-protected environment, followed by air cooling for tempering heat treatment. The bimetallic composite continuous oil tube is then wound onto drum I. The medium-frequency induction heating coil of the medium-frequency heat treatment furnace is 150mm long, and the internal circulating water flow rate is 100m³ / h during water injection for cooling. 3 / h S6 inserts the plug equipped with a one-way positive pressure valve into the front end of the bimetallic composite coiled tubing, and uses argon arc welding to weld it to the end of the bimetallic composite coiled tubing at the external bevel position, thus completing the processing of the bimetallic composite coiled tubing for air lift operations.

2. The method for manufacturing a bimetallic composite coiled tubing for air lift operations according to claim 1, characterized in that, The end of the tube is welded with a union.

3. The method for manufacturing a bimetallic composite coiled tubing for air lift operations according to claim 1, characterized in that, When splicing the steel strips at both ends in S2, the ends of the two steel strips to be spliced ​​together need to be cut into a 45° bevel with respect to the length of the steel strips using a shearing machine. Then, the two steel strips are welded using a plasma welding process with ERNiCrMo-3 nickel-based alloy welding wire. After welding is completed, the weld reinforcement is ground to be flush with the base material.

4. The method for manufacturing a bimetallic composite coiled tubing for air lift operations according to claim 1, characterized in that, In step S2, before preparing the tubular component, for steel strips that need to be extended, the two end faces of the steel strips need to be milled into type I bevels.

5. The method for manufacturing a bimetallic composite coiled tubing for air lift operations according to claim 1, characterized in that, The welding processes for S5 and S6 are the same, both using ERNiCrMo-3 nickel-based alloy welding wire, welding current of 75A, voltage of 16V, welding speed of 4.5cm / min, and shielding gas of argon with a gas flow rate of 12L / min.

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