A method of manufacturing a dual metal composite pipe for oil and gas wells

Abstract

The application provides a method for manufacturing a double-metal composite steel pipe for oil and gas wells, which forms a double-metal metallurgical composite interface under a thread mechanical device, explosion welding and high-temperature hot extrusion of a base material and an inner lining stainless steel material, improves the double-metal interface bonding strength, and relieves the deficiency of poor cooperative deformation of the existing double-metal composite pipe interface. The method can effectively improve the bonding strength of the double-metal composite pipe interface, the bearing capacity under the composite load and the interface cooperative deformation capacity, meets the requirement of machining the pipe blank into a special thread joint with high sealing pressure, and the double-metal composite steel pipe prepared by the method can be used for manufacturing and producing oil pipes, casing pipes and other oil pipes in the oil and gas industry, and has important engineering significance for safely and effectively solving the oil and gas corrosion problem.

Description

[Technical Field]

[0001] This invention belongs to the field of oil and gas exploration and development and uses petroleum pipes, and specifically relates to a method for manufacturing bimetallic composite steel pipes for oil and gas wells. [Background Technology]

[0002] As oil and gas field development moves towards "deep, high-temperature, high-pressure, and corrosive conditions," downhole oil and gas tubing is susceptible to corrosion due to complex conditions such as high temperature, high pressure, corrosive media, bacteria, and high flow rates. For example, in shale gas wells, sulfate-reducing bacteria can cause perforation corrosion starting from the inner wall of the tubing, even leading to pipe bursts and leaks during operation, seriously affecting the safety of oil and gas well production. Currently, to address increasingly severe corrosion problems, high-alloy stainless steel, nickel-based alloys, and even titanium alloys are commonly used as corrosion-resistant tubing materials. However, this significantly increases the cost of oil and gas resource extraction and, to some extent, limits resource production capacity. Therefore, there is an urgent need to adopt economical and effective corrosion-resistant tubing methods to solve the severe corrosion problems under harsh corrosive conditions.

[0003] Bimetallic composite pipes are made by bonding a layer of corrosion-resistant alloy lining material onto a carbon steel or alloy steel substrate. This combines the high strength of carbon steel with the corrosion resistance of the lining material, reducing the amount of alloy steel used, significantly lowering costs, and overcoming the shortcomings of non-metallic composite pipes, such as poor high-temperature resistance, low bonding strength, and high construction requirements. With increasingly stringent requirements for pipe cost and performance in oil and gas fields, this has become one of the main research directions for economical corrosion-resistant pipes in the oil and gas industry.

[0004] Currently, many domestic enterprises and research institutes have conducted relevant research on the preparation process of bimetallic composite pipes. The relatively mature metallurgical composite processes include centrifugal casting, hot extrusion, explosive welding, hot rolling, weld overlay composite and pressure anchor composite, etc. The products are generally used in the field of oil and gas transportation, and the steel pipes are continuously welded; while the oil and gas well downhole tubing is generally connected by threads, especially deep wells and high-pressure gas wells, which require the processing of gas-tight threaded joints.

[0005] According to the research results, during the downhole service of oil and gas tubing strings, the connection points of the tubing strings experience complex stress conditions under combined loads such as tensile / compressive forces, internal and external pressures, sealing contact pressures, and bending, which places high demands on the material properties of the steel pipes. Currently, common bimetallic composite processes both domestically and internationally improve interfacial microstructure and bonding strength through optimized manufacturing processes and methods. However, in actual production, they still cannot effectively solve problems such as compositional gradients, interfacial precipitates, and insufficient interfacial deformation coordination at the bimetallic composite pipe interface, thus creating potential risks for subsequent failures during the service life of the steel pipes.

[0006] Therefore, there is an urgent need for a manufacturing method for producing bimetallic composite steel pipes for oil and gas wells to solve the above problems. [Summary of the Invention]

[0007] To address the aforementioned problems, this invention provides a method for manufacturing bimetallic composite steel pipes for oil and gas wells. This method can produce bimetallic composite pipe interfaces with helix angles, combining mechanical thread fit with the metallurgical properties of bimetallic materials. This effectively improves the bonding strength of the bimetallic composite pipe interface, its load-bearing capacity under combined loads, and its interface deformation coordination ability. It also meets the requirements for processing special threaded joints with high sealing pressure into the pipe blank. This bimetallic composite steel pipe can be used in the oil and gas industry to manufacture oil pipes, casings, and other oil pipe materials, and has significant engineering implications for safely and effectively solving oil and gas corrosion problems.

[0008] This invention is achieved through the following technical solution, providing a method for manufacturing bimetallic composite steel pipes for oil and gas wells, comprising the following steps:

[0009] S1 manufactures and processes outer base pipes;

[0010] S2 production and processing of inner lining pipes;

[0011] S3 assembles the outer base tube and the inner liner tube and performs hot extrusion to produce a bimetallic composite tube blank.

[0012] S4 processes the bimetallic composite tube blank to obtain a bimetallic composite steel pipe.

[0013] Specifically, S1 is implemented according to the following scheme:

[0014] S11 involves cutting continuously cast round billets made of carbon steel or low alloy steel into the required length and forging them. After forging, the billets are machined into hollow outer base tube blanks. The raw materials for preparing the hollow outer base tube blanks are: C-Mn alloy steel with the addition of appropriate amounts of microalloying elements such as V and Nb. Specifically, calculated by mass percentage, the components include: C 0.20-0.25%, Si 0.2-0.4%, Mn 1.25-1.40%, P≤0.015%, S≤0.005%, Cr≤0.1%, Ni≤0.1%, Mo≤0.05%, Nb 0.02-0.03%, V 0.04-0.07%, with the balance being Fe and unavoidable impurities.

[0015] S12 processes the hollow outer base tube blank into an assembly with internal threads to obtain the outer base tube blank;

[0016] S13 performs water removal, oil removal, and drying treatment on the internal threads of the outer base tube blank to ensure that the thread surface is clean and free of contamination.

[0017] Specifically, S2 is implemented according to the following scheme:

[0018] The outer surface of the thick-walled stainless steel seamless tube is machined and peeled off, and then precision machined into an inner liner tube. At the same time, the inner liner tube is machined into an assembly with external threads, and the external threads are dehydrated, degreased, and dried to make the surface of the external threads clean and free of contamination. The material of the inner liner tube is austenitic stainless steel.

[0019] Specifically, S3 is implemented according to the following scheme:

[0020] S31 assembles the outer base tube and inner liner tube into a threaded assembly, and uses the explosive composite method to make a composite blank from the threaded assembly;

[0021] S32 heats the composite billet to a specified temperature and then hot-extrudes it using a horizontal extruder to produce a bimetallic composite pipe billet.

[0022] S33 involves cutting the bimetallic composite pipe blank, heat treatment, straightening, and sandblasting the outer surface.

[0023] S34 involves testing the tube blank after S33 treatment using ultrasonic testing and one or more non-destructive testing methods. After passing the test, the tube ends are threaded, couplings are tightened, hydrostatic pressure is tested, a protective ring is applied, marking is done, and painting is done to obtain the bimetallic composite steel pipe.

[0024] Specifically, in S31, when the outer base tube and inner liner tube are assembled, the circumferential gap is 1-1.5mm. This facilitates the subsequent explosive bonding to form an impact effect, so as to use the high-speed impact effect of explosive bonding to form a metallurgical composite layer between the bimetallic layers and enhance the interface performance of the composite steel pipe.

[0025] Specifically, the explosive bonding method in S31 adopts the internal explosive bonding method, which allows the detonation point to start from the center of the assembly during the explosive bonding process. Detonation from the center to both sides can shorten the explosive bonding time, eliminate residual air between the bimetallic interfaces during mechanical assembly, and improve the bimetallic bonding coverage. In S32, the heating is first carried out in an atmosphere-protected resistance furnace and heated to a specified temperature of 1100℃-1200℃.

[0026] Specifically, in S32, if the dimensions of the bimetallic composite tube blank do not meet the design requirements, the bimetallic composite tube blank needs to be cold rolled or cold drawn to ensure that the bimetallic composite tube blank meets the design dimensions.

[0027] In particular, in this invention, since the high-temperature rheological properties of the two metals are quite different, in order to make the high-temperature rheological rates of the two metals similar, S32 adopts a positive extrusion method with an extrusion rate of 250mm-400mm / s, which can avoid the fracture problem caused by the tensile stress between the bimetallic layers.

[0028] Specifically, the heat treatment in S33 adopts online medium-frequency induction heating for tempering heat treatment. This step uses medium-frequency induction heating to improve heating efficiency and has the advantages of fast heating rate. This heating method can reduce the adverse effects of heating on the corrosion-resistant lining layer and avoid deterioration of the corrosion resistance of the lining layer. The medium-frequency heating rate is 15℃-30℃ / s. After this step, the base material can obtain the required strength and toughness.

[0029] The present invention also provides a bimetallic composite steel pipe for oil and gas wells manufactured using a method for manufacturing bimetallic composite steel pipes for oil and gas wells. The interface of the bimetallic composite steel pipe has a spiral helix angle similar to that of a thread, and the interface bonding strength is ≥500MPa.

[0030] Compared with the prior art, the present invention provides a method for manufacturing bimetallic composite steel pipes for oil and gas wells, which has the following beneficial effects:

[0031] 1. This method forms a bimetallic composite interface between the base material and the inner stainless steel pipe under threaded mechanical device, explosive welding and high temperature hot extrusion, which improves the bonding strength of the bimetallic interface and alleviates the shortcomings of poor synergistic deformation of the existing bimetallic composite pipe interface.

[0032] 2. The bimetallic interface prepared by this method has the characteristics of circular thread helix angle and helix, which plays a dual role of "threaded connection" and metallurgical bonding. It can effectively avoid defects such as composite pipe delamination, inner lining collapse and interface stress concentration in bimetallic composite steel pipes.

[0033] In summary, the bimetallic composite steel pipes for oil and gas wells prepared using this method have advantages such as high strength, high toughness, high corrosion resistance, high strength of the bimetallic interface, and stable quality.

Detailed Implementation Methods

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0035] In this invention, the mass percentage (wt%) of the smelting chemical elements in the outer casing and inner lining of the bimetallic composite steel pipe are shown in Table 1 below. The outer casing is made of low-carbon C-Mn alloy steel with added microalloying elements such as Nb and V; the inner lining is made of 316L stainless steel.

[0036] Table 1. Smelting chemical composition of the bimetallic composite steel pipe of the present invention.

[0037] Lining 0.02 0.34 0.55 0.010 0.003 17.8 2.0 9.9 / / base tube 0.22 0.35 1.32 0.012 0.0039 0.083 0.022 0.070 0.05 0.02

[0038] Example 1

[0039] This embodiment manufactures a bimetallic composite sleeve with dimensions of Ф139.7mm*9.17mm. The specific manufacturing steps are as follows:

[0040] Step 1: Cut the Φ360mm*1000mm continuous casting round billet of low alloy steel with the base pipe composition described in Table 1 to the designed length and forge it. Drill and finish the forged billet to form a Φ229mm*1000mm hollow outer base pipe billet. Then, process the hollow billet into an assembly with internal threads as required. Subsequently, perform water removal, oil removal, and drying on the internal threads of the outer base pipe billet to keep the thread surface clean and free of contamination.

[0041] Step 2: The outer surface of the Φ232mm*36mm*1020mm thick-walled seamless inner liner tube described in Table 1 is machined and peeled off to produce a Φ229mm*35mm*1020mm inner liner tube. The inner liner tube is then machined into an assembly with external threads. Simultaneously, the internal threads of the outer base tube blank are treated with dehydration, degreasing, and drying to ensure the thread surface is clean and free of contamination.

[0042] Step 3: Assemble the outer substrate and inner liner tube prepared in Step 1 and Step 2 into a threaded assembly. Use the explosive composite method to make a composite blank and cool it to room temperature.

[0043] Step 4: The composite billet prepared in Step 3 is reheated to a specified temperature of 1100℃~1150℃ and directly hot-extruded into a bimetallic composite tube billet with a length of more than 20m and a specification of Φ139.7mm*9.17mm using a 60MN horizontal extrusion press. After running on the roller conveyor for a period of time, it is immersed in a water tank for cooling. The hot extrusion rate is 250mm~330mm / s, and the inner lining thickness is 2.5mm±0.5mm.

[0044] Step 5: The Φ139.7mm*9.17mm bimetallic composite tube blank produced in Step 4 is cut to length and then heated to 930℃ in multiple medium-frequency induction heating furnaces for internal and external quenching. Subsequently, it is heated to 700℃ in a medium-frequency induction heating furnace for tempering. After tempering, it is straightened in a straightening machine, and finally, the inner and outer surfaces are sandblasted to remove heat treatment oxide scale. The quenching heating at 930℃ is maintained for 8 minutes, the tempering heating at 700℃ is maintained for 16 minutes, the medium-frequency induction heating rate is 15℃~25℃ / s, and the straightening machine inlet temperature is ≥550℃.

[0045] Step 6: After step 5, the tube blank is tested for defects using ultrasonic testing and one or more other non-destructive testing methods. After passing the test, the tube ends are threaded, couplings are tightened, hydrostatic pressure test is performed, protective rings are applied, marking is applied, and painting is done.

[0046] Example 2

[0047] This embodiment manufactures a bimetallic composite oil pipe with dimensions of Ф88.9mm*7.34mm. The specific manufacturing steps are as follows:

[0048] Step 1: Cut the Φ320mm*600mm continuous casting round billet of low alloy steel with the base pipe composition described in Table 1 to the designed length and forge it. Drill and finish the forged billet to form a Φ170mm*600mm hollow outer base pipe billet. Then, process the hollow billet into an assembly with internal threads as required. Subsequently, perform water removal, oil removal, and drying on the internal threads of the outer base pipe billet to keep the thread surface clean and free of contamination.

[0049] Step 2: The outer surface of the Φ172mm*30mm*620mm thick-walled seamless inner liner tube described in Table 1 is machined and peeled off to produce a Φ170mm*28mm*620mm inner liner tube. The inner liner tube is then machined into an assembly with external threads. Simultaneously, the internal threads of the outer base tube blank are treated with dehydration, degreasing, and drying to ensure the thread surface is clean and free of contamination.

[0050] Step 3: Assemble the outer substrate and inner liner tube prepared in Step 1 and Step 2 into a threaded assembly. Use the explosive composite method to make a composite blank and cool it to room temperature.

[0051] Step 4: The composite billet prepared in Step 3 is reheated to a specified temperature within the range of 1150℃~1200℃, and directly hot-extruded into a 10m long bimetallic composite tube with a diameter of Φ127mm*11mm using a 60MN horizontal extrusion press. After running on the roller conveyor for a short distance, it is immersed in a water tank for cooling. Subsequently, the Φ127mm*11mm long tube is fed into a cold rolling mill and reduced in diameter to Φ88.9mm*7.34mm bimetallic composite tube in three passes. The hot extrusion rate is 320mm~380mm / s, and the thickness of the inner lining layer of the cold-rolled tube billet is 1.5mm±0.25mm.

[0052] Step 5: The Φ88.9mm*7.34mm bimetallic composite tube blank produced in Step 4 is cut to length and then heated to 915℃ using multiple medium-frequency induction heating furnaces for internal and external quenching. Subsequently, it is heated to 680℃ in a medium-frequency induction heating furnace for tempering. After tempering, it is straightened using a straightening machine, and finally, the inner and outer surfaces are sandblasted to remove heat treatment oxide scale. The quenching heating at 915℃ is maintained for 10 minutes, the tempering heating at 680℃ is maintained for 20 minutes, the medium-frequency induction heating rate is 20℃~30℃ / s, and the straightening machine inlet temperature is ≥530℃.

[0053] Step 6: After step 5, the tube blank is subjected to ultrasonic testing and one or more other non-destructive testing methods. After passing the test, the tube ends are processed with gas-tight threaded joints, couplings, hydrostatic pressure test, protective rings, marking and painting.

[0054] To test the performance of the steel pipes prepared in the above embodiments, the following explanation is provided through experiments.

[0055] The mechanical properties and bonding strength of the bimetallic composite steel pipes from Examples 1-2 were tested, and the results are shown in Table 3 below. Table 3 shows that the yield strength of the bimetallic composite steel pipes manufactured in Examples 1 and 2 ranges from 665 MPa to 785 MPa, the tensile strength from 815 MPa to 930 MPa, the elongation from 24% to 30%, the transverse impact energy at 0℃ is 115 J to 132 J, the longitudinal impact energy at 0℃ is 146 J to 155 J, and the interfacial bonding strength is 519 MPa to 672 MPa. Therefore, the method described in this invention can manufacture bimetallic composite steel pipes of 80 ksi-110 ksi steel grade, and the prepared bimetallic composite steel pipes have good strength-toughness matching and high interfacial bonding strength.

[0056] Table 3. Test results of mechanical properties and bonding strength of the bimetallic composite steel pipe of the present invention.

[0057]

Claims

1. A method for manufacturing a bimetallic composite steel pipe for oil and gas wells, characterized in that, Including the following steps: S1 is used to produce and process the outer base tube, and S1 is implemented according to the following scheme: S11 involves cutting continuously cast round billets made of carbon steel or low alloy steel into the required length and forging them. After forging, the billets are machined into hollow outer base tube blanks. The chemical composition of the hollow outer base tube blanks, calculated by mass percentage, includes the following components: C 0.20-0.25%, Si 0.2-0.4%, Mn 1.25-1.40%, P ≤ 0.015%, S ≤ 0.005%, Cr ≤ 0.1%, Ni ≤ 0.1%, Mo ≤ 0.05%, Nb 0.02-0.03%, V 0.04-0.07%, with the balance being Fe. S12 processes the hollow outer base tube blank into an assembly with internal threads to obtain the outer base tube blank; S13 performs water removal, oil removal, and drying treatment on the internal threads of the outer base tube blank to ensure that the thread surface is clean and free of contamination. S2 production and processing of inner lining pipes; S3 involves assembling the outer base tube and the inner liner tube, followed by hot extrusion to produce a bimetallic composite tube blank. S3 is specifically implemented according to the following scheme: S31 assembles the outer base tube and inner liner tube into a threaded assembly, and uses the explosive composite method to make a composite blank from the threaded assembly; S32 heats the composite billet to a specified temperature and then hot-extrudes it using a horizontal extruder to produce a bimetallic composite pipe billet. S33 involves cutting the bimetallic composite pipe blank, heat treatment, straightening, and sandblasting the outer surface. S34 involves using ultrasonic testing and one or more non-destructive testing methods to inspect the pipe blank after S33 treatment. After passing the inspection, the pipe ends are threaded, the couplings are tightened, a hydrostatic test is performed, a protective ring is applied, and the pipe is marked and painted to obtain a bimetallic composite steel pipe. S4 processes the bimetallic composite tube blank to obtain a bimetallic composite steel pipe.

2. The method for manufacturing a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, S2 is implemented according to the following scheme: The outer surface of the thick-walled stainless steel seamless tube is machined and peeled off, and then precision machined into an inner liner tube. At the same time, the inner liner tube is machined into an assembly with external threads, and the external threads are dehydrated, degreased, and dried to make the surface of the external threads clean and free of contamination. The material of the inner liner tube is austenitic stainless steel.

3. The method for manufacturing a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, In S31, the circumferential gap between the outer base tube and the inner liner tube is 1-1.5 mm.

4. The method for manufacturing a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, The explosion recombination method in S31 adopts the internal explosion recombination method, and the heating in S32 first adopts the atmosphere protection resistance furnace to heat to the specified temperature of 1100℃-1200℃.

5. A method for manufacturing a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, In step S32, the bimetallic composite tube blank is subjected to cold rolling or cold drawing.

6. The method for manufacturing a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, The S32 uses a positive extrusion method with an extrusion rate of 250mm-400mm / s.

7. The method for manufacturing a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, The heat treatment in S33 is carried out by online medium-frequency induction heating, with a medium-frequency heating rate of 15℃-30℃ / s.

8. A dual metal composite pipe for oil and gas wells manufactured by the method according to any one of claims 1 to 7, characterized by The interface of the bimetallic composite steel pipe has a spiral helix angle similar to that of a thread, and the interface bonding strength is ≥500MPa.

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