Coiled tubing for oil and gas well and manufacturing method

Abstract

The invention provides a continuous pipe for an oil and gas well and a manufacturing method, the continuous pipe for the oil and gas well comprises a pipe body, one end of the pipe body is provided with a plugging structure, and the pipe body is provided with a connecting hole used for connecting the pipe body and the oil and gas well; the gas lift valve is arranged on the inner wall of the pipe body, the gas lift valve is provided with a gas inlet and a gas outlet, and the gas inlet is matched with the connecting hole. The problem that in the prior art, efficient liquid drainage of an oil and gas well is limited is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas pipe manufacturing, in particular to a continuous pipe for oil and gas well and a manufacturing method. BACKGROUND

[0002] In the later stage of production, the wellbore liquid loading phenomenon often occurs in oil and gas wells, which affects the productivity and even leads to production stoppage. In order to solve this problem, the commonly used gas lift liquid discharge process is to inject high-pressure gas into the oil-casing annulus to displace the liquid into the oil pipe, thereby reducing the flow pressure gradient and discharging the liquid to the wellhead. However, this method has certain limitations, such as ground compressor output pressure limitation, increased bottom hole back pressure, etc.

[0003] In order to overcome these limitations, continuous pipe gas lift liquid discharge technology and gas lift valve gas lift liquid discharge technology have emerged. The continuous pipe gas lift liquid discharge technology injects high-pressure nitrogen or natural gas into the continuous pipe, uses the characteristics of gas expansion and rapid dispersion, and circulates the liquid in the well after gas-liquid mixing, which can effectively discharge the residual liquid in the well. The gas lift valve gas lift liquid discharge technology is to install a gas lift valve on the oil pipe to displace the high-pressure gas and the liquid in the oil-casing annulus into the oil pipe, and gradually reduce the liquid level in the oil pipe, thereby discharging the wellbore liquid loading and restoring the production of the oil and gas well.

[0004] However, these two technologies also have certain limitations. The continuous pipe gas lift liquid discharge technology needs to use a high-power compressor, which will suppress the formation when gas lifting in deep wells and low-pressure formations. The gas lift valve gas lift liquid discharge technology can only be applied to gas wells that have installed gas lift valves, which lacks flexibility.

[0005] As can be seen from the above, the existing technology has the problem of limited efficient liquid discharge of oil and gas wells. SUMMARY

[0006] The main purpose of the present application is to provide a continuous pipe for oil and gas well and a manufacturing method to solve the problem of limited efficient liquid discharge of oil and gas wells in the prior art.

[0007] In order to achieve the above purpose, according to one aspect of the present application, a continuous pipe for oil and gas well is provided, comprising: a pipe body, one end of the pipe body is provided with a plugging structure, and the pipe body is provided with a connecting hole for connecting the pipe body and the oil and gas well; a gas lift valve, the gas lift valve is arranged on the inner wall of the pipe body, and the gas lift valve has an air inlet and an air outlet, the air inlet is matched with the connecting hole.

[0008] Further, the material of the pipe body is duplex stainless steel, the yield strength is >600Mpa, the tensile strength is >750MPa, the elongation is >35%, the width range is 1000-1300mm, the length is >300m, and the thickness range is 3.0-6.5mm.

[0009] Further, the pipe body is made of 2205 duplex stainless steel, with yield strength of 690 MPa, tensile strength of 780 MPa, elongation of 38%, width of 1180 mm, length of 480 m, and thickness of 4.4 mm.

[0010] Further, the gas lift valve is made of duplex stainless steel, with a diameter of less than 25 mm and a length of less than 280 mm.

[0011] Further, the coiled tubing for oil and gas wells further comprises a plurality of identification parts, the plurality of gas lift valves are arranged on the inner wall of the pipe body along the length direction of the pipe body and located on the same straight line, the distance between two adjacent gas lift valves in the plurality of gas lift valves gradually increases in the direction away from the plugging structure, and the plurality of identification parts are arranged on the pipe body one by one corresponding to the plurality of gas lift valves.

[0012] Further, the opening and closing pressures of the plurality of gas lift valves gradually decrease in the direction away from the plugging structure.

[0013] Further, the gas lift valve comprises a valve body, a first valve rod and a second valve rod, the valve body has a first channel, a second channel and a third channel connected in sequence, the first valve rod and the second valve rod are movably arranged in the first channel and the third channel respectively, and are used for controlling the opening and closing of the first channel and the second channel and the third channel and the second channel.

[0014] Further, the gas lift valve further comprises a first sealing member and a second sealing member, the first sealing member and the second sealing member are connected with the two ends of the valve body respectively, and are used for sealing the valve body.

[0015] Further, the gas lift valve further comprises a first elastic member and a second elastic member, the first elastic member and the second elastic member are accommodated in the first channel and the third channel respectively, the first elastic member is located between the first sealing member and the first valve rod, and the second elastic member is located between the second sealing member and the second valve rod.

[0016] Further, the gas lift valve further comprises a gas pressure piston, the gas pressure piston is arranged in the first channel, and the first elastic member is in communication with the gas pressure piston.

[0017] According to another aspect of the present application, a manufacturing method of a coiled tubing for oil and gas wells is provided, which is used for manufacturing the coiled tubing for oil and gas wells, and comprises the following steps: S1: selecting duplex stainless steel as the material for preparing the pipe body, and selecting a plurality of gas lift valves with different opening and closing pressures; S2: preparing a steel strip, welding a plurality of steel strips to lengthen the steel strip, and marking the position; S3: arranging the plurality of gas lift valves on the pipe body along the axial direction of the pipe body at intervals, and spraying a plurality of identification parts; S4: welding the steel strip into the pipe body; S5: removing burrs and performing heat treatment on the pipe body; and S6: detecting the pipe body, and winding the qualified pipe body.

[0018] Further, the specific steps of S2 are: S21: cutting the duplex stainless steel into multiple steel strips with the same width, processing the two ends of the steel strips into 45° bevel U-shaped grooves, selecting multiple steel strips to weld into a combined steel strip, using ER2209 welding wire to weld, and using plasma welding under the protection of argon atmosphere; S22: after welding, solid solution treatment is performed on the weld, using medium-frequency heating to rapidly heat to 1050℃, keeping for 2min, water cooling, polishing and cleaning the weld, and setting the position of the weld as "0 position".

[0019] Further, the specific steps of S3 are: S31: the multiple gas lift valves are a first gas lift valve, a second gas lift valve, a third gas lift valve, a fourth gas lift valve and a fifth gas lift valve, the fifth gas lift valve is spaced apart from the positioning mark by 20m; S32: the first gas lift valve, the second gas lift valve, the third gas lift valve, the fourth gas lift valve and the fifth gas lift valve are welded on one side of the combined steel strip at intervals of 800m, 650m, 500m and 300m; S33: on the other side of the combined steel strip, multiple mark parts corresponding one by one to the first gas lift valve, the second gas lift valve, the third gas lift valve, the fourth gas lift valve and the fifth gas lift valve are sprayed.

[0020] Further, the specific steps of S4 are: S41: the combined steel strip is formed by the roller forming mode of alternating arrangement of horizontal rollers and vertical rollers; S42: the combined steel strip is welded by longitudinal laser welding, and the purity of the nitrogen protection during the welding process is ≥99.7%.

[0021] Further, the specific steps of S5 are: S51: local heat treatment, using high-frequency induction heating and inert atmosphere protection, rapidly heating the weld position to 1020-1100℃, keeping for 1-5min, and water cooling; S52: whole pipe heat treatment, using medium-frequency induction heating and inert atmosphere protection, rapidly heating the pipe body to 500-1000℃, keeping for 0.5-10min, and water cooling the pipe body below 300℃.

[0022] The oil and gas well continuous pipe provided by the application comprises a pipe body and a gas lift valve, one end of the pipe body is provided with a plugging structure, the pipe body is provided with a connecting hole for connecting the pipe body and the oil and gas well, the gas lift valve is arranged on the inner wall of the pipe body, the gas lift valve has an air inlet and an air outlet, the air inlet is matched with the connecting hole, the one end of the pipe body is plugged by the plugging structure, the gas lift valve is arranged in the pipe body and the air inlet of the gas lift valve is connected with the connecting hole, so that the pipe body and the oil and gas well are communicated; during use, the whole continuous pipe is inserted into a designated position of the oil and gas well, the accumulated liquid in the oil and gas well is discharged into the pipe body through the gas lift valve, and the accumulated liquid flows out along the other end of the pipe body; compared with the traditional gas pressure liquid discharge mode, the opening pressure of the gas lift valve is low, the accumulated liquid in the oil and gas well can be effectively discharged, the gas lift valve can be taken out after the liquid discharge is completed, so that the next oil and gas well can be entered for liquid discharge, the use is flexible, the stratum is not affected, the continuous pipe can be repeatedly used, the liquid discharge cost of the oil and gas well is reduced, the liquid discharge needs of oil and gas wells with different depths can be met, and the efficiency of the oil and gas well liquid discharge is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the application, serve to explain the application. In the drawings:

[0024] Figure 1 A working state structure schematic diagram of the oil and gas well continuous pipe in one specific embodiment of the application is shown;

[0025] Figure 2 A structure schematic diagram of the closed state of the gas lift valve in one specific embodiment of the application is shown;

[0026] Figure 3 A structure schematic diagram of the open state of the gas lift valve in one specific embodiment of the application is shown;

[0027] Figure 4 A manufacturing flowchart of the oil and gas well continuous pipe in one specific embodiment of the application is shown;

[0028] Figure 5 A working flowchart of the oil and gas well continuous pipe in one specific embodiment of the application is shown.

[0029] In the above drawings, the following reference signs are used:

[0030] 10. Pipe body; 20. Gas lift valve; 21. Valve body; 211. Air inlet; 212. Air outlet; 213. First channel; 214. Second channel; 215. Third channel; 22. First valve stem; 23. Second valve stem; 24. First sealing element; 25. Second sealing element; 26. First elastic element; 27. Second elastic element; 28. Gas piston; 29. ​​Welding point; 30. Oil and gas well; 40. Working machine; 50. Gas injection device. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0033] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0034] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0035] To address the problem of limited efficient fluid drainage in existing oil and gas wells, this invention provides a coiled tubing for oil and gas wells and a manufacturing method thereof.

[0036] like Figure 1 As shown, the coiled tubing for oil and gas wells includes a tubing body 10 and a gas lift valve 20. One end of the tubing body 10 is equipped with a sealing structure, and the tubing body 10 has a connection hole for connecting the tubing body 10 and the oil and gas well 30. The gas lift valve 20 is located on the inner wall of the tubing body 10 and has an inlet 211 and an outlet 212, with the inlet 211 being adapted to the connection hole.

[0037] One end of the pipe body 10 is sealed by a sealing structure. The gas lift valve 20 is installed inside the pipe body 10, and its air inlet 211 is connected to the connection hole, thus connecting the pipe body 10 and the oil and gas well 30. In use, the entire continuous pipe is inserted into the designated position of the oil and gas well 30, and the accumulated liquid in the oil and gas well 30 is discharged into the pipe body 10 through the gas lift valve 20. The accumulated liquid flows out along the other end of the pipe body 10. Compared with the traditional pneumatic drainage method, the opening pressure of the gas lift valve 20 is lower, which can effectively drain the accumulated liquid in the oil and gas well 30. After the drainage is completed, the gas lift valve 20 can be taken out by pulling out the continuous pipe, so that the next oil and gas well 30 can be drained. It is flexible in use, does not affect the formation, and the continuous pipe can be reused, reducing the drainage cost of the oil and gas well 30. It can meet the drainage needs of oil and gas wells 30 at various depths and ensure the high efficiency of the drainage of oil and gas wells 30.

[0038] In this embodiment, the tube body 10 is made of duplex stainless steel with a yield strength >600 MPa, tensile strength >750 MPa, elongation >35%, width range of 1000-1300 mm, length >300 m, and thickness range of 3.0-6.5 mm.

[0039] Specifically, after the tube body 10 is prepared, it needs to be wound onto the turntable of the working machine 40. The tube body 10 needs to have a certain elongation rate; if the elongation rate is too low, it will be difficult to store the tube body 10. Optionally, duplex stainless steel can be made of materials such as 2205 or 2507, which can be selected according to actual needs and cost.

[0040] In this embodiment, the tube body 10 is made of 2205 duplex stainless steel with a yield strength of 690MPa, a tensile strength of 780MPa, an elongation of 38%, a width of 1180mm, a length of 480mm, and a thickness of 4.4mm.

[0041] Specifically, the tube 10 formed under these parameters has better performance, and finally forms a continuous tube with parameters as shown in Table 1.

[0042] Table 1

[0043]

[0044] In this embodiment, the air lift valve 20 is made of duplex stainless steel, the diameter of the air lift valve 20 is <25mm, and the length of the air lift valve 20 is <280mm.

[0045] Specifically, the air lift valve 20 is made of the same material as the pipe body 10, which facilitates processing and production, improves material utilization, and avoids waste.

[0046] In this embodiment, the continuous tubing for oil and gas wells also includes a marking section. There are multiple marking sections and multiple gas lift valves 20. The multiple gas lift valves 20 are spaced apart along the length of the tubing 10 on the inner wall of the tubing 10 and are located on the same straight line. The distance between two adjacent gas lift valves 20 gradually increases in the direction away from the sealing structure. The multiple marking sections are correspondingly arranged on the tubing 10 with the multiple gas lift valves 20.

[0047] Specifically, the air lift valves 20 are spaced apart on the pipe wall before the pipe body 10 is formed. After the pipe body 10 is formed, the air lift valves 20 are enclosed within the pipe body 10. Multiple air lift valves 20 are arranged in a straight line on the pipe body 10, which facilitates the subsequent spraying of the marking section. Alternatively, the marking section can be sprayed first and then the air lift valves 20 are installed. The one-to-one arrangement of multiple air lift valves 20 and multiple marking sections allows for the determination of the opening status of the air lift valves 20. If one air lift valve 20 malfunctions, its location can be quickly determined. At the same time, the marking section is located on the outer wall of the pipe body 10, and the state of liquid drainage can be determined by the exposed marking section. Optionally, the marking section is integrally formed with the pipe body 10, and the marking section is formed by the outer wall of the pipe body 10 being concave inward or convex outward along the radial direction of the pipe body 10.

[0048] In another embodiment of this application (not shown), a plurality of air lift valves 20 are misaligned on the inner wall of the pipe body 10.

[0049] Optionally, a sensor is also installed at the position corresponding to the marking part of the pipe body 10 to determine the liquid accumulation in the oil and gas well 30.

[0050] In this embodiment, the opening pressure of the plurality of air lift valves 20 gradually increases in the direction away from the sealing structure.

[0051] Specifically, the usage of coiled tubing in oil and gas wells is as follows: Figure 5 As shown, the workover machine 40 first reaches the vicinity of the oil and gas well 30 and then extends the pipe body 10 into the designated position of the oil and gas well 30. Subsequently, it seals the wellhead of the oil and gas well 30, leaving only the pipe body 10 and the inlet of the gas injection pipe of the gas injection device 50. Since the diameter of the pipe body 10 is smaller than the diameter of the oil and gas well 30, an annulus is formed. The gas injection device 50 is started to inject one of the following into the annulus: natural gas from the adjacent well, high-pressure nitrogen, or compressed natural gas. When the gas injection begins, the pressure of the entire annulus is at its maximum, and multiple gas lift valves 20 are opened. The liquid accumulated in the annulus enters the pipe body 10 through the gas lift valve 20's inlet 211 and outlet 212, and is finally discharged from the other end. After releasing the pressure of the oil and gas well 30, the workover machine 40 retracts the pipe body 10.

[0052] In this process, by setting gas lift valves 20 with different opening pressures, and the gas lift valve 20 that is farther away from the sealing structure has a higher opening pressure, the gas pressure injected into the annulus can be gradually reduced when the gas lift valve 20 at the top of the pipe body 10 is exposed. This allows the gas lift valves 20 to close sequentially from high to low, thus preventing the liquid in the annulus from being discharged and avoiding the continuous injection of high-pressure gas into the oil and gas well 30, which could damage the formation.

[0053] like Figures 2-3 As shown, the air lift valve 20 includes a valve body 21, a first valve stem 22, and a second valve stem 23. The valve body 21 has a first channel 213, a second channel 214, and a third channel 215 that are connected in sequence. The first valve stem 22 and the second valve stem 23 are respectively movably disposed in the first channel 213 and the third channel 215 to control the on / off state between the first channel 213 and the second channel 214, and between the third channel 215 and the second channel 214.

[0054] Specifically, the end of the first valve stem 22 is provided with a spherical protrusion, which is adapted to the opening of the first channel 213. When the pressure is low, the air lift valve 20 remains closed, that is, the gas entering the valve body 21 through the air inlet 211 cannot lift the first valve stem 22 or move the second valve stem 23, so that the gas or liquid cannot enter the pipe body 10 through the air outlet 212 of the air lift valve 20.

[0055] Furthermore, the second valve stem 23 is also provided with a spherical protrusion, and the surface of the spherical protrusion at the end of the second valve stem 23 is treated with an anti-erosion KNM22 polymer ceramic coating to improve the wear resistance of the material surface. Optionally, the end of the first valve stem 22 is also coated with KNM22 polymer ceramic. To ensure the sealing and integrity of the air lift valve 20, the surface of the air lift valve 20 is coated with a high-temperature resistant silicon nitride ceramic coating to improve its temperature resistance up to 1000℃.

[0056] In this embodiment, the valve body 21 has multiple welding points 29 on the side near the pipe body 10. The valve body 21 is connected to the inner wall of the pipe body 10 through the welding points 29, thereby realizing that the gas lift valve 20 and the pipe body 10 are connected as a whole. Unlike traditional gas lift working cylinders, it does not need to be connected to the pipe body 10 through threaded joints or welded joints. Moreover, the built-in gas lift valve 20 does not need to consider the situation of being hit by the pipe body 10. This method improves the service life and reliability of the continuous tubing for oil and gas wells.

[0057] In this embodiment, the air inlet 211 and two air outlets 212 of the air lift valve 20 are spaced apart, and the two air outlets 212 are located on both sides of the valve body 21.

[0058] like Figures 2-3As shown, the air lift valve 20 also includes a first sealing element 24 and a second sealing element 25, which are respectively connected to both ends of the valve body 21 for sealing the valve body 21.

[0059] Specifically, the two ends of the air lift valve 20 are welded or threaded to the first sealing member 24 and the second sealing member 25 to ensure the airtightness of the air lift valve 20.

[0060] like Figures 2-3 As shown, the air lift valve 20 also includes a first elastic element 26 and a second elastic element 27. The first elastic element 26 and the second elastic element 27 are respectively housed in the first channel 213 and the third channel 215. The first elastic element 26 is located between the first sealing element 24 and the first valve stem 22, and the second elastic element 27 is located between the second sealing element 25 and the second valve stem 23.

[0061] Specifically, both the first sealing member 24 and the second sealing member 25 are provided with connecting protrusions extending axially along the valve body 21. The first elastic member 26 and the second elastic member 27 are respectively connected to the first sealing member 24 and the second sealing member 25. When the gas pressure entering the gas lift valve 20 decreases, the first elastic member 26 and the second elastic member 27 reset the first valve stem 22 and the second valve stem 23, and re-seal the first channel 213 and the third channel 215.

[0062] Optionally, both the first elastic element 26 and the second elastic element 27 are return springs.

[0063] like Figures 2-3 As shown, the air lift valve 20 also includes a pneumatic piston 28, which is disposed in the first channel 213, and the first elastic element 26 is connected to the pneumatic piston 28.

[0064] Specifically, the first elastic element 26 is a bellows. The first elastic element 26 is connected to the air outlet of the pneumatic piston 28. By injecting gas into the valve core of the pneumatic piston 28, after the bellows is squeezed, the pneumatic piston 28 inflates the bellows, causing the bellows to inflate and push the first valve stem 22 in the opposite direction.

[0065] The present invention also provides a method for manufacturing coiled tubing for oil and gas wells. The method for manufacturing the above-mentioned coiled tubing for oil and gas wells includes the following steps: S1: Selecting duplex stainless steel as the material for preparing the tubing body 10, and selecting multiple gas lift valves 20 with different opening and closing pressures; S2: Preparing steel strips, welding multiple steel strips to extend the steel strips, and marking them for positioning; S3: Arranging multiple gas lift valves 20 at intervals along the axial direction of the tubing body 10, and spraying multiple markings; S4: Welding the steel strips into the tubing body 10; S5: Deburring and heat-treating the tubing body 10; S6: Inspecting the tubing body 10, and winding the qualified tubing body 10.

[0066] Specifically, the production process of continuous tubes is as follows: Figure 4 As shown, in step S5, a test roll is also made, and the tube 10 is wound onto the test roll reel until the "0 position" is wound onto the test roll reel; the inspection in step S6 includes rewinding the continuous tube from the test roll reel onto the turntable of the work machine 40, and measuring the length of the tube 10, non-destructive testing, and hydrostatic pressure testing during the rewinding process, and re-spraying the air lift valve 20 to ensure the corresponding accuracy.

[0067] In this embodiment, the specific steps of S2 are as follows: S21: Cut duplex stainless steel into multiple steel strips of the same width, and process the two ends of the steel strips into 45° bevels with U-shaped bevels. Select multiple steel strips and weld them into a combined steel strip. Use ER2209 welding wire for welding. During welding, plasma welding is performed under argon atmosphere protection. S22: After welding, perform solution treatment on the weld. Use medium frequency heating to quickly heat to 1050°C, hold for 2 minutes, water cool, grind and clean the weld, and set the position of the weld as "position 0".

[0068] Specifically, the length, diameter, and wall thickness of the pipe body 10 are designed according to requirements. A shearing machine is used to cut duplex stainless steel into steel strips with a width ranging from 139mm to 229mm. Steel strips of the same length as those on the forming equipment production line are selected to hold multiple gas lift valves 20. Multiple subsequent steel strips are selected to be extended from this steel strip. Since multiple gas lift valves 20 have already been placed on this steel strip, the lengths of the other steel strips can be arbitrary, ensuring that the entire formed pipe body 10 meets the depth requirements of the oil and gas well 30.

[0069] Optionally, to improve the welding effect of two adjacent steel strips, the ends of the two adjacent steel strips are provided with a slope, which can be any angle from 40° to 50°, and the shape is not limited to the above-mentioned U-shape, but can also be I-shape or V-shape, so that the two steel strips form a slanted weld, thereby improving the welding effect.

[0070] Furthermore, various welding methods such as friction stir welding, plasma filler wire welding, or argon arc welding can be used to increase welding speed. To further ensure the uniformity of the two-phase microstructure of the weld, the weld is rapidly heated to 1020-1100℃ in a protective atmosphere using medium-frequency heating, held for 0.5-5 minutes, and then water-cooled. Optionally, welding wires other than ER2209 can be used, such as ER2594.

[0071] In this embodiment, the steel strip cutting production process also includes a steel strip length recording device, which is at least one of a laser length recorder, an electronic length recorder, and an image processing length recorder.

[0072] When spraying the "0" positioning mark, use a laser machine, inkjet printer, or paint spraying method to spray the mark.

[0073] In this embodiment, the specific steps of S3 are as follows: S31: The multiple air lift valves 20 are respectively a first air lift valve, a second air lift valve, a third air lift valve, a fourth air lift valve and a fifth air lift valve, with the fifth air lift valve spaced 20m apart from the positioning mark; S32: The first air lift valve, the second air lift valve, the third air lift valve, the fourth air lift valve and the fifth air lift valve are welded to one side of the combined steel strip at intervals of 800m, 650m, 500m and 300m; S33: On the other side of the combined steel strip, multiple marking parts corresponding to the first air lift valve, the second air lift valve, the third air lift valve, the fourth air lift valve and the fifth air lift valve are sprayed.

[0074] Specifically, the setting and selection of the gas lift valve 20 are not arbitrary. The pressure selection of the gas lift valve 20 is affected by the well depth and downhole pressure. As the well depth increases, the downhole pressure is greater. Therefore, the rated pressure of the gas lift valve 20 near the bottom of the oil and gas well 30 needs to be able to withstand the high-pressure environment downhole. At the same time, the installation position and number of gas lift valves 20 installed on the steel strip are related to the length of the pipe body 10 and the well depth. The gas lift valve 20 is installed near the bottom of the pipe body 10. The spacing between multiple gas lift valves 20 gradually decreases from top to bottom, and the opening and closing pressures of the gas lift valve 20 also decrease from top to bottom. This allows for better control of the closing sequence of the gas lift valve 20, so that the gas and liquid in the annulus can flow into the pipe body 10 through the air inlet 211 opening of the gas lift valve 20, thereby optimizing the gas lift drainage effect. Specific parameters are shown in Table 2.

[0075] Table 2

[0076]

[0077] Furthermore, the selection and installation positions of multiple air lift valves 20 can be referred to Table 2. In actual installation, starting from "position 0", the fifth air lift valve is first set, with the fifth air lift valve 20m away from "position 0" (too long or too short a distance is not conducive to drainage). Since the steel belt has been lengthened, it is only necessary to hold "position 0", rotate the collection plate on the working machine 40 to obtain the required length, and open a through hole at this position. To facilitate the installation of the air lift valve 20, the diameter of the through hole can be slightly larger than the diameter of the air inlet 211 of the air lift valve 20. Optionally, it can be slightly larger than the diameter of the air inlet 211 of the air lift valve 20. 1. Diameter 3.6mm; After installation, use welding wire to weld the welding point 29 of the air lift valve 20 to the steel strip. The length direction of the air lift valve 20 is consistent with the length direction of the steel strip. Then, grind the part of the air inlet 211 that extends beyond the steel strip and widen the air inlet 211 so that the air inlet 211 is flush with the surface of the steel strip and fits tightly with the through hole on the steel strip, thereby realizing the installation of the fifth air lift valve. Repeat the above process to install the first air lift valve, the second air lift valve, the third air lift valve and the fourth air lift valve according to Table 2, and spray the corresponding marking part on the other side of the steel strip.

[0078] In this embodiment, the specific steps of S4 are as follows: S41: The combined steel strip is formed by a roller forming method with alternating horizontal and vertical rollers; S42: The combined steel strip is longitudinally laser welded, and the purity of nitrogen protection during the welding process is ≥99.7%.

[0079] Specifically, the deformation is distributed by multiple frames using horizontal and vertical rollers, the edge of the steel strip is bent by edge bending, and the center of the steel strip is bent by circumferential bending, which ensures the reliability of forming and the non-destructive installation of the air lift valve 20, and controls the end forming bevel gap of the steel strip to ≤0.1mm.

[0080] Furthermore, the defocusing amount was +6mm, the laser power was 5.6Kw, the welding speed was 3.5m / min, and the external burrs of the weld were removed by grinding to produce a straight seam duplex stainless steel continuous pipe with a diameter of Φ50.8mm and a wall thickness of 4.4mm.

[0081] In this embodiment, the specific steps of S5 are as follows: S51: Local heat treatment, using high-frequency induction heating and inert atmosphere protection, rapidly heating the weld position to 1020-1100℃, holding for 1-5 minutes, and water cooling; S52: Full pipe heat treatment, using medium-frequency induction heating and inert atmosphere protection, rapidly heating the pipe body 10 to 500-1000℃, holding for 0.5-10 minutes, and water cooling the pipe body 10 below 300℃.

[0082] Specifically, by using the aforementioned local heat treatment and full-pipe heat treatment methods, the toughness of the pipe is improved, the residual stress in the weld and pipe body during the pipe manufacturing process is reduced, and finally, a duplex stainless steel continuous pipe with good comprehensive performance is obtained.

[0083] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: By setting a continuous tubing for oil and gas wells including a pipe body 10 and a gas lift valve 20, a sealing structure is provided at one end of the pipe body 10, and a connection hole for connecting the pipe body 10 and the oil and gas well 30 is provided on the pipe body 10. The gas lift valve 20 is located on the inner wall of the pipe body 10 and has an inlet 211 and an outlet 212. The inlet 211 is adapted to the connection hole. By sealing one end of the pipe body 10 with the sealing structure, and setting the gas lift valve 20 inside the pipe body 10 with the inlet 211 of the gas lift valve 20 connected to the connection hole, the connection between the pipe body 10 and the oil and gas well 30 is achieved. The entire coiled tubing is inserted into the designated position of the oil and gas well 30. The accumulated liquid in the oil and gas well 30 is discharged into the tubing body 10 through the gas lift valve 20. The accumulated liquid flows out along the other end of the tubing body 10. Compared with the traditional pneumatic drainage method, the opening pressure of the gas lift valve 20 is lower, which can effectively drain the accumulated liquid in the oil and gas well 30. After the drainage is completed, the gas lift valve 20 can be taken out by pulling out the coiled tubing, so that the next oil and gas well 30 can be drained. It is flexible in use, will not affect the formation, and the coiled tubing can be reused, which reduces the drainage cost of the oil and gas well 30. It can meet the drainage needs of oil and gas wells 30 at various depths and ensure the high efficiency of the drainage of oil and gas wells 30.

[0084] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0085] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coiled tubing for use in oil and gas wells, characterized by The oil and gas well continuous pipe comprises a pipe body (10), a gas lift valve (20) and a plurality of identification parts. The pipe body (10) is made of duplex stainless steel, and has a yield strength of >600Mpa, a tensile strength of >750MPa, an elongation of >35%, a width range of 1000-1300mm, a length of >300m, and a thickness range of 3.0-6.5mm. The pipe body (10) is made of 2205 duplex stainless steel, and has a yield strength of 690MPa, a tensile strength of 780MPa, an elongation of 38%, a width of 1180mm, a length of 480m, and a thickness of 4.4mm.

2. The coiled tubing for use in oil and gas wells according to claim 1, characterized in that, The gas lift valve (20) is made of duplex stainless steel, has a diameter of <25mm, and a length of <280mm.

3. The coiled tubing for use in oil and gas wells according to claim 2, characterized in that, The plurality of gas lift valves (20) are arranged on the inner wall of the pipe body (10) along the length direction of the pipe body (10) and located on the same straight line, the distance between two adjacent gas lift valves (20) gradually increases in the direction away from the sealing structure, and the plurality of identification parts are arranged on the pipe body (10) one by one corresponding to the plurality of gas lift valves (20).

4. The coiled tubing for use in oil and gas wells according to claim 1, characterized in that, The opening pressure of the plurality of gas lift valves (20) gradually increases in the direction away from the sealing structure.

5. The coiled tubing for use in oil and gas wells according to claim 1, characterized in that, The gas lift valve (20) comprises a valve body (21), a first valve rod (22) and a second valve rod (23), the valve body (21) has a first channel (213), a second channel (214) and a third channel (215) connected in sequence, the first valve rod (22) and the second valve rod (23) are movably arranged in the first channel (213) and the third channel (215) respectively, and are used for controlling the opening and closing of the first channel (213) and the second channel (214) and the third channel (215) and the second channel (214).

6. The coiled tubing for use in oil and gas wells according to claim 5, characterized in that, The gas lift valve (20) further comprises a first sealing member (24) and a second sealing member (25), the first sealing member (24) and the second sealing member (25) are connected with both ends of the valve body (21) respectively, and are used for sealing the valve body (21).

7. The coiled tubing for use in oil and gas wells according to claim 1, characterized in that, ​ 8. The coiled tubing for use in oil and gas wells according to claim 7, characterized in that, ​ 9. The coiled tubing for use in oil and gas wells according to claim 8, characterized in that, The gas lift valve (20) further comprises a first elastic member (26) and a second elastic member (27), the first elastic member (26) and the second elastic member (27) are respectively accommodated in the first channel (213) and the third channel (215), the first elastic member (26) is located between the first blocking member (24) and the first valve rod (22), and the second elastic member (27) is located between the second blocking member (25) and the second valve rod (23).

10. The coiled tubing for use in oil and gas wells according to claim 9, characterized in that, The gas lift valve (20) further comprises a gas pressure piston (28), the gas pressure piston (28) is arranged in the first channel (213), and the first elastic member (26) communicates with the gas pressure piston (28).

11. A method of manufacturing a coiled tubing for use in oil and gas wells, characterized by, The continuous pipe for oil and gas wells described in any one of claims 1 to 10 is manufactured, including the following steps: S1: selecting duplex stainless steel as the material for preparing the pipe body (10), and selecting a plurality of gas lift valves (20) with different opening and closing pressures; S2: preparing a steel strip, welding a plurality of the steel strips to lengthen the steel strip, and performing positioning marking; S3: arranging a plurality of the gas lift valves (20) on the pipe body (10) along the axial direction of the pipe body (10) at intervals, and spraying a plurality of identification parts; S4: welding the steel strip into the pipe body (10); S5: performing burr removal and heat treatment on the pipe body (10); S6: detecting the pipe body (10), and winding the qualified pipe body (10).

12. The method of manufacturing coiled tubing for use in oil and gas wells according to claim 11, characterized in that, The specific steps of S2 are: S21: cutting the duplex stainless steel into a plurality of steel strips with the same width, machining the two ends of the steel strip into a 45° bevel U-shaped groove, selecting a plurality of the steel strips to weld into a combined steel strip, using ER2209 welding wire to weld, and performing plasma welding under the protection of an argon atmosphere during welding; S22: after welding, performing solid solution treatment on the weld, using intermediate frequency heating to rapidly heat to 1050℃, maintaining for 2 min, water cooling, grinding and cleaning the weld, and setting the position of the weld as "0 position".

13. The method of making a coiled tubing for use in oil and gas wells according to claim 11, wherein, The specific steps of S3 are: S31: the plurality of gas lift valves (20) are respectively a first gas lift valve, a second gas lift valve, a third gas lift valve, a fourth gas lift valve and a fifth gas lift valve, and the fifth gas lift valve is spaced apart from the positioning mark by 20 m; S32: the first gas lift valve, the second gas lift valve, the third gas lift valve, the fourth gas lift valve and the fifth gas lift valve are welded on one side of the combined steel strip at intervals of 800 m, 650 m, 500 m and 300 m; S33: on the other side of the combined steel strip, a plurality of identification parts corresponding to the first gas lift valve, the second gas lift valve, the third gas lift valve, the fourth gas lift valve and the fifth gas lift valve are respectively sprayed.

14. The method of making a coiled tubing for use in oil and gas wells according to claim 11, wherein, The specific steps of S4 are: S41: the combined steel strip is formed by a roll forming mode in which horizontal rollers and vertical rollers are alternately arranged; S42: the combined steel strip is welded by longitudinal laser welding, and the purity of nitrogen protection during the welding process is ≥99.7%.

15. The method of making a coiled tubing for use in oil and gas wells according to claim 11, wherein, The specific steps of S5 are: S51: local heat treatment, using high-frequency induction heating, inert atmosphere protection, the weld position is rapidly heated to 1020-1100℃, holding 1-5min, water cooling; S52: whole tube heat treatment, using medium-frequency induction heating, inert atmosphere protection, the tube body (10) is rapidly heated to 500-1000℃, holding 0.5-10min, the tube body (10) is water cooled below 300℃.

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