Manufacturing method of bimetal composite steel pipe for oil and gas well

Abstract

According to the manufacturing method of the bimetal composite steel pipe for the oil and gas well, a bimetal metallurgical composite interface is formed by a base material and a lining stainless steel material under the conditions of a thread mechanical device, explosive welding and high-temperature hot extrusion, and the bonding strength of the bimetal interface is improved; and the defect that the synergistic deformation of an interface of an existing bimetal composite pipe is poor is overcome. According to the method, the bonding strength of the interface of the bimetal composite pipe, the bearing capacity under the combined load and the interface coordinating deformation capacity can be effectively improved, and the requirement that the pipe blank can be used for machining a high-sealing-pressure special threaded connector is met; the bimetal composite steel pipe prepared by the method can be used for manufacturing and producing oil pipes, sleeves and other petroleum pipes in the petroleum and natural gas industry, and has important engineering significance for safely and effectively solving the problem of oil gas corrosion.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas exploration and production oil pipes, and particularly relates to a manufacturing method of a bimetal composite steel pipe for oil and gas wells.

Background Art

[0002] With the development of oil and gas field exploitation towards the direction of "deep layer, high temperature, high pressure and corrosion working conditions", the downhole oil and gas pipe string is easily corroded on the inner wall of the pipe string under complex working conditions such as high temperature, high pressure, corrosive medium, bacteria and high flow rate. For example, in shale gas wells, the sulfate reducing bacteria cause perforation corrosion starting from the inner wall of the oil pipe, and even lead to accidents such as in-service pipeline bursting and leakage of the pipe body, seriously affecting the production safety of oil and gas wells. At present, in order to solve the increasingly harsh corrosion problems, corrosion-resistant pipes such as high-alloy stainless steel, nickel-based alloy, and even titanium alloy are often used, which greatly increases the cost of oil and gas resource exploitation and restricts the resource production increase ability to a certain extent. Therefore, it is urgent to adopt an economical and effective corrosion-resistant pipe method to solve the serious corrosion problems under harsh corrosion working conditions.

[0003] The bimetal composite pipe is a corrosion-resistant alloy lining material compounded on a carbon steel or alloy steel matrix, combining the two major advantages of the high strength of carbon steel and the corrosion resistance of the lining material. This method reduces the consumption of corrosion-resistant alloy pipes, significantly reduces the cost, and overcomes the disadvantages of non-metal composite pipes such as poor high-temperature resistance, low bonding strength, and high construction requirements. With the increasing requirements of oil and gas fields for the cost and performance of pipes, it has become one of the main research directions of economical corrosion-resistant pipes in the oil and gas industry.

[0004] Nowadays, many domestic enterprises and scientific research institutions have carried out relevant research on the preparation process of bimetal composite pipes. The relatively mature metallurgical composite processes include centrifugal casting, hot extrusion, explosion welding, hot rolling, surfacing composite and press anchor composite, etc. And the products are generally applied to the oil and gas transportation field, and the steel pipes are continuously welded; while the downhole pipe string of oil and gas wells is generally connected by threads, especially for deep wells, high-pressure gas wells, etc., which require the processing of gas-tight threaded joints.

[0005] According to the research results: during the downhole service of the oil and gas pipe string, the stress situation of the pipe string connection part is complex under the action of combined loads such as tension / compression force, internal and external pressure, contact pressure of the seal surface and bending, etc., which puts forward high requirements for the material properties of the steel pipe. The common bimetal composite processes at home and abroad, through optimizing the manufacturing process and means, improve the interface structure and interface bonding strength, but in actual production, the problems such as composition gradient, interface precipitation phase and insufficient interface coordinated deformation ability existing at the interface of the bimetal composite pipe still cannot be effectively solved, laying a hidden danger for the subsequent failure of the steel pipe during service.

[0006] In view of this, there is an urgent need for a manufacturing method for preparing a bimetal composite steel pipe for oil and gas wells to solve the above problems.

Summary of the Invention

[0007] To solve the above problems, the present invention provides a manufacturing method for a bimetallic composite steel pipe for oil and gas wells. This method can prepare a bimetallic composite pipe interface with a spiral helix angle, combining mechanical thread fitting and the metallurgy of bimetallic materials, effectively improving the bonding strength of the bimetallic composite pipe interface, the load-bearing capacity under composite loads, the interface coordinated deformation ability, etc., meeting the requirements for processing high-sealing-pressure special thread joints for pipe blanks. This bimetallic composite steel pipe can be used in the oil and gas industry to manufacture and produce oil pipes, casing pipes, and other oil pipes, which has important engineering significance for safely and effectively solving the problem of oil and gas corrosion.

[0008] The present invention is realized through the following technical solutions. A manufacturing method for a bimetallic composite steel pipe for oil and gas wells is provided, including the steps:

[0009] S1 Process and manufacture the outer base pipe;

[0010] S2 Process and manufacture the inner lining pipe;

[0011] S3 Assemble the outer base pipe and the inner lining pipe, and perform hot extrusion treatment to make a bimetallic composite pipe blank;

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

[0013] Specifically, the implementation of S1 is as follows:

[0014] S11 Cut a continuous casting round billet made of carbon steel or low alloy steel into the required length and perform forging. After forging, machine it into a hollow outer base pipe blank. The preparation raw materials of the hollow outer base pipe blank are: on the basis of C-Mn alloy steel, add appropriate amounts of micro-alloying elements such as V and Nb. Specifically calculated by mass percentage, it 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%, and the balance is Fe and unavoidable impurities;

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

[0016] S13 Remove water, oil, and dry the internal threads of the outer base pipe blank to make the thread surface clean and pollution-free.

[0017] Specifically, the implementation of S2 is as follows:

[0018] The outer surface of the thick-walled seamless stainless steel pipe is machined and peeled, and then finely processed into a lining pipe. At the same time, the lining pipe is processed into a fitting with an external thread, and the external thread is dehydrated, degreased, and dried to make the surface of the external thread clean and pollution-free. The material of the lining pipe is: austenitic stainless steel.

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

[0020] S31 Assemble the outer base pipe and the lining pipe into a threaded fitting, and use the explosive cladding method to make the composite blank.

[0021] S32 Heat the composite blank to the specified temperature, and use a horizontal extruder to perform hot extrusion to make the billet of the bimetal composite pipe.

[0022] S33 Cut the head, perform heat treatment, straighten, and sandblast the outer surface of the billet of the bimetal composite pipe.

[0023] S34 Use ultrasonic and more than one non-destructive testing method to detect the billet after S33 treatment. After passing the inspection, perform threading at the pipe end, screw on the coupling, perform a hydrostatic test, install a protective ring, spray marking, and painting to obtain the bimetal composite steel pipe.

[0024] Specifically, in S31, when assembling the outer base pipe and the lining pipe, the circumferential gap is a void of 1 - 1.5 mm. This can facilitate the subsequent impact effect of explosive cladding, so as to use the explosive cladding to form a high-speed impact effect to form a metallurgical composite layer between the bimetal layers and enhance the interface performance of the composite steel pipe.

[0025] Specifically, in S31, the internal explosive cladding method is used for the explosive cladding method. In this way, during the explosive cladding process, the initiation point initiates from the center position of the fitting. From the center position to both sides, the explosive cladding time can be shortened, the air residue between the bimetal interfaces during mechanical assembly can be excluded, and the bimetal composite coverage rate can be improved. In S32, first use an atmosphere-protected resistance furnace for heating to the specified temperature of 1100°C - 1200°C.

[0026] Specifically, in S32, if the specification size of the billet of the bimetal composite pipe does not meet the design requirements, cold rolling or cold drawing treatment needs to be performed on the made billet of the bimetal composite pipe, so as to ensure that the billet of the bimetal composite pipe that meets the design specification size is made.

[0027] Specifically, in the present invention, due to the large difference in the high-temperature rheological properties of the two metals, in order to make the high-temperature flow rates of the two metals close, S32 adopts the forward extrusion method, and the extrusion rate is 250 mm - 400 mm / s. This can avoid the fracture problem caused by the tensile stress between the bimetal layers.

[0028] Specifically, in S33, heat treatment is carried out by online intermediate frequency induction heating for quenching and tempering heat treatment. This step uses intermediate frequency induction heating to improve the heating efficiency, and has advantages such as a fast heating rate. Using this heating method can reduce the adverse effects of heating on the corrosion-resistant layer of the inner lining and avoid deteriorating the corrosion resistance of the inner lining layer. Among them, the intermediate frequency heating rate is 15°C - 30°C / s. After processing by this step, the matrix material can obtain the required strength and toughness.

[0029] The present invention also provides a bimetal composite steel pipe for oil and gas wells manufactured by using the manufacturing method according to any one of claims 1 - 9. The interface of the bimetal composite steel pipe has a feature similar to the helix angle of a thread, and the interface bonding strength ≥ 500 MPa.

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

[0031] 1. This method forms a bimetal composite interface between the matrix material and the inner lining stainless steel pipe under a thread mechanical device, explosion welding, and high-temperature hot extrusion, improving the bimetal interface bonding strength and alleviating the deficiency of poor co-deformation existing in the interface of the existing bimetal composite pipe;

[0032] 2. The bimetal interface prepared by this method has the features of a round thread helix angle and a helix, giving play to the dual roles of "thread connection" and metallurgical bonding, and enabling the bimetal composite steel pipe to effectively avoid defects such as delamination of the composite pipe, collapse of the inner lining pipe, and concentrated interface stress distribution.

[0033] In summary, the bimetal composite steel pipe for oil and gas wells prepared by this method has the advantages of high strength, high toughness, high corrosion resistance, high strength of the bimetal interface, and stable quality.

Specific Embodiments

[0034] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in conjunction with specific embodiments.

[0035] In the present invention, the mass percentages (wt%) of the smelting chemical elements of the outer pipe and the inner lining pipe for preparing the bimetal composite steel pipe are as shown in Table 1 below. Among them, the outer pipe is a low-carbon C-Mn alloy steel, and micro-alloying elements such as Nb and V are added; the inner lining pipe is 316L stainless steel.

[0036] Table 1 Smelting Chemical Compositions of the Bimetal Composite Steel Pipe of the Present Invention

[0037] Material C Si Mn P S Cr Mo Ni V Nb Inner lining 0.02 0.34 0.55 0.010 0.003 17.8 2.0 9.9 / / Base pipe 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 casing with dimensions of Ф139.7mm * 9.17mm, and its specific manufacturing steps are as follows:

[0040] Step 1: Cut the Ф360mm * 1000mm continuous casting round billet of low alloy steel with the base tube composition described in Table 1 into the designed length and perform forging. After forging, drill and finish it into a hollow outer base tube blank with the specification of Ф229mm * 1000mm. Subsequently, process the hollow blank into a fitting with internal threads as required. Then, perform treatments such as water removal, oil removal, and air drying on the internal threads of the outer base tube blank to keep the thread surface clean and pollution-free.

[0041] Step 2: Perform external surface machining and peeling on the Ф232mm * 36mm * 1020mm thick-walled seamless lining tube with the lining material described in Table 1, and finish it into a lining tube with the specification of Ф229mm * 35mm * 1020mm. Subsequently, process the lining tube into a fitting with external threads. At the same time, perform treatments such as water removal, oil removal, and air drying on the internal threads of the outer base tube blank to keep the thread surface clean and pollution-free.

[0042] Step 3: Assemble the outer matrix and the lining tube prepared in Step 1 and Step 2 into a threaded fitting, and use the explosive cladding method to make a composite blank, and cool it to room temperature.

[0043] Step 4: Reheat the composite blank made in Step 3 to a specified temperature within the range of 1100°C to 1150°C, and directly hot extrude it into a bimetallic composite pipe blank with the specification of Ф139.7mm * 9.17mm and a length of more than 20m using a 60MN horizontal extrusion press, and immerse it in a water tank for cooling after a certain section on the roller path. The hot extrusion rate is 250mm - 330mm / s, and the thickness of the lining layer is 2.5mm ± 0.5mm.

[0044] Step 5: Cut the head and size the Ф139.7mm * 9.17mm bimetallic composite pipe blank made in Step 4, and perform quenching treatment with internal spraying and external spraying by heating it to 930°C using multiple intermediate frequency induction heating furnaces. Subsequently, heat it to 700°C using an intermediate frequency induction heating furnace for tempering treatment. After tempering, enter the straightening machine for straightening, and finally perform sandblasting treatment on the inner and outer surfaces to remove heat treatment oxide scales, etc. The constant temperature time at 930°C during quenching heating is 8min, the constant temperature time at 700°C during tempering heating is 16min, the intermediate frequency induction heating rate is 15°C - 25°C / s, and the inlet temperature of the straightening machine is ≥550°C.

[0045] Step 6: Detect the tube blank after Step 5 using ultrasonic and more than 1 other non-destructive testing methods. After passing the inspection, perform operations such as threading at the tube ends, screwing on the couplings, hydrostatic testing, installing protective rings, spraying marks, and painting.

[0046] Example 2

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

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

[0049] Step 2: Perform external surface machining and peeling on a thick-walled seamless lining pipe with a specification of Φ172mm * 30mm * 620mm of the lining material described in Table 1, and finish it into a lining pipe with a specification of Φ170mm * 28mm * 620mm. Subsequently, process the lining pipe into an assembly with external threads. At the same time, perform treatments such as water removal, oil removal, and air drying on the internal threads of the outer base pipe blank to keep the thread surface clean and pollution-free.

[0050] Step 3: Assemble the outer matrix and the lining pipe prepared in Step 1 and Step 2 into a threaded assembly, and use the explosive cladding method to make a composite blank, and cool it to room temperature.

[0051] Step 4: Reheat the composite blank made in Step 3 to a specified temperature within the range of 1150°C to 1200°C, and directly hot extrude it into a rough bimetallic composite pipe with a specification of Φ127mm * 11mm and a length of about 10m using a 60MN horizontal extrusion press, and immerse it in a water pool for cooling after a certain period on the roller table. Subsequently, send the rough pipe with a specification of Φ127mm * 11mm made into a cold rolling mill, and reduce the diameter to a bimetallic composite pipe with a specification of Φ88.9mm * 7.34mm through 3 passes. The hot extrusion rate is 320mm - 380mm / s, and the thickness of the inner lining layer of the pipe blank after cold rolling is 1.5mm ± 0.25mm.

[0052] Step 5: Cut the head and size the bimetallic composite pipe blank with a specification of Φ88.9mm * 7.34mm made in Step 4, and heat it to 915°C using multiple intermediate frequency induction heating furnaces for quenching treatment with internal spraying and external spraying. Subsequently, heat it to 680°C using an intermediate frequency induction heating furnace for tempering treatment. After tempering, enter a straightening machine for straightening, and finally perform sandblasting treatment on the inner and outer surfaces to remove heat treatment oxide scales, etc. The constant temperature time at 915°C during quenching heating is 10min, the constant temperature time at 680°C during tempering heating is 20min, the intermediate frequency induction heating rate is 20°C - 30°C / s, and the inlet temperature of the straightening machine is ≥530°C.

[0053] Step 6: After step 5, the tube blank is inspected by ultrasonic and more than one other non-destructive inspection method. After passing the inspection, gas-tight threaded joints are machined at the tube ends, couplings are screwed on, hydrostatic tests are carried out, protective rings are installed, marking and painting are done, etc.

[0054] In order to test the performance of the steel pipes prepared in the above embodiments, the following is explained through experiments.

[0055] The mechanical properties and bonding strength of the bimetallic composite steel pipes in Examples 1-2 were detected, and the test results are shown in Table 3 below. It can be seen from Table 3 that: the yield strength range of the bimetallic composite steel pipes manufactured in Examples 1 and 2 is 665 MPa - 785 MPa, the tensile strength is 815 MPa - 930 MPa, the elongation is 24% - 30%, the transverse impact energy at 0 °C is 115 J - 132 J, the longitudinal impact energy at 0 °C is 146 J - 155 J, and the interface bonding strength value is 519 MPa - 672 MPa. Thus, it can be seen that: the method of the present invention can manufacture bimetallic composite steel pipes with a steel grade of 80 ksi - 110 ksi, and the prepared bimetallic composite steel pipes have the characteristics of good strength and toughness matching and high interface bonding strength.

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

[0057]

Claims

1. A manufacturing method of a bimetallic composite steel pipe for oil and gas wells, characterized in that, Including the steps: S1: Produce and process the outer base pipe; S2: Produce and process the inner lining pipe; S3: Assemble the outer base pipe and the inner lining pipe, and conduct hot extrusion treatment to make a bimetal composite pipe blank; S4: Process the bimetal composite pipe blank to obtain a bimetal composite steel pipe.

2. The manufacturing method of a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, The specific implementation of S1 is as follows: S11: Cut the continuous casting round billet made of carbon steel or low alloy steel into the required length and conduct forging. After forging, machine it into a hollow outer base pipe blank. The chemical composition of the hollow outer base pipe blank is calculated by mass percentage and 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%, and the balance is Fe; S12: Process the hollow outer base pipe blank into a fitting with internal threads to obtain the outer base pipe blank; S13: Remove water, oil, and blow dry the internal threads of the outer base pipe blank to make the thread surface clean and pollution - free.

3. The manufacturing method of a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, The specific implementation of S2 is as follows: Conduct machining and peeling on the outer surface of the thick - wall stainless - steel seamless pipe, and finish - machine it into an inner lining pipe. At the same time, process the inner lining pipe into a fitting with external threads, and remove water, oil, and blow dry the external threads to make the external thread surface clean and pollution - free. The material of the inner lining pipe is austenitic stainless steel.

4. A manufacturing method of a bimetallic composite steel pipe for oil and gas wells according to claim 1, characterized in that, The specific implementation of S3 is as follows: S31: Assemble the outer base pipe and the inner lining pipe into a threaded fitting, and use the explosive cladding method to make a composite blank; S32: Heat the composite blank to the specified temperature and conduct hot extrusion using a horizontal extruder to make a bimetal composite pipe blank; S33: Cut the head, conduct heat treatment, straighten, and sandblast the outer surface of the bimetal composite pipe blank; S34: Use ultrasonic and more than one non - destructive testing method to detect the pipe blank after the treatment of S33. After passing the inspection, conduct pipe end threading, coupling screwing, hydrostatic test, installing a protective ring, spraying marks, and painting to obtain the bimetal composite steel pipe.

5. A manufacturing method of a bimetallic composite steel pipe for oil and gas wells according to claim 4, characterized in that, In S31, when assembling the outer base pipe and the inner lining pipe, the circumferential gap is a 1 - 1.5 mm void.

6. A manufacturing method of a bimetal composite steel pipe for oil and gas wells according to claim 4, characterized in that, In S31, the explosive cladding method uses the internal explosive cladding method. In S32, first use an atmosphere - protected resistance furnace to heat to the specified temperature of 1100℃ - 1200℃.

7. A manufacturing method of a bimetallic composite steel pipe for oil and gas wells according to claim 4, characterized in that, In S32, the made bimetal composite pipe blank is subjected to cold rolling or cold drawing treatment.

8. A manufacturing method of a bimetallic composite steel pipe for oil and gas wells according to claim 4, characterized in that, S32 adopts the forward extrusion method, and the extrusion rate is 250 mm - 400 mm / s.

9. A method for manufacturing a bimetallic composite steel pipe for oil and gas wells according to claim 4, characterized in that, In S33, the heat treatment is carried out by online medium - frequency induction heating for quenching and tempering heat treatment, and the medium - frequency heating rate is 15℃ - 30℃ / s.

10. A bimetallic composite steel pipe for oil and gas wells manufactured by the manufacturing method described in any one of claims 1-9, characterized in that, The interface of the bimetal composite steel pipe has a characteristic similar to the helix angle of the thread, and the interface bonding strength ≥ 500 MPa.

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