Coiled tubing tractor

Abstract

This invention relates to a coiled tubing traction device, comprising a first traction device and a second traction device, symmetrically installed within the well. Each traction device includes a centralizing and tensioning unit, a drive assembly, and a hydraulic unit connected in sequence. The centralizing and tensioning unit includes a central shaft, multiple tensioning bearings, multiple centralizing blocks, a first piston, and a centralizing and tensioning housing. The centralizing and tensioning housing has tensioning holes and centralizing holes. Shoulders and linkage mechanisms are evenly arranged circumferentially around the central shaft at positions corresponding to the tensioning holes. The tensioning bearings are hinged to the shoulders via the linkage mechanisms. Inclined grooves are evenly arranged around the central shaft at positions corresponding to the centralizing holes. Each inclined groove slidably connects to a centralizing block. A spring is installed between two adjacent centralizing blocks on the same circumference. A first piston and a return spring are installed between the bottom of the inclined groove at the lowest point of the central shaft and the bottom of the centralizing and tensioning housing. This invention can effectively solve the problem of high resistance in coiled tubing operations and improve drilling efficiency.

Description

Technical Field

[0001] This invention relates to coiled tubing downhole traction tool technology in the field of oil and gas field engineering, specifically a coiled tubing traction device. Background Technology

[0002] Coiled tubing technology, with its advantages of high operational efficiency, minimal formation contamination, and uninterrupted fluid circulation, is now widely used in oil and gas field drilling, completion, well washing, acidizing, and fracturing operations, and is one of the core technologies for oil and gas reservoir exploration and development. Currently, oil and gas development is gradually extending to deeper, unconventional, and "low-pressure, low-permeability, low-production" reservoirs. Wells with complex structures, such as extended reach wells and long horizontal sections, are becoming the mainstream well types. These wells have complex trajectories, high friction between the tubing and the wellbore, and difficulty in extending the tubing string, which can even lead to accidents such as tubing buckling, self-locking, and stuck drill bits, severely limiting the application scope of coiled tubing technology. Summary of the Invention

[0003] The purpose of this invention is to provide a coiled tubing puller that solves problems such as buckling and self-locking caused by high friction between the coiled tubing and the wellbore in existing coiled tubing operations.

[0004] The technical solution adopted by this invention to solve its technical problem is as follows: This coiled tubing traction device consists of a first traction device and a second traction device, which are symmetrically installed in the oil well. Each traction device includes a centralizing and tensioning unit, a drive assembly, and a hydraulic unit connected in sequence. The centralizing and tensioning unit includes a central shaft, multiple tensioning bearings, multiple centralizing blocks, a first piston, and a centralizing and tensioning outer shell. The central shaft passes through the centralizing and tensioning outer shell. Tensioning holes are evenly arranged on the upper part of the centralizing and tensioning outer shell, and the lower part of the centralizing and tensioning outer shell is formed... The circumference is provided with a centering hole. Shoulders and linkage mechanisms are evenly arranged circumferentially at the corresponding positions of the center shaft and the tensioning hole. The tensioning bearing is hinged to the shoulder through the linkage mechanism. Inclined grooves are evenly arranged at the corresponding positions of the center shaft and the centering hole. Each inclined groove is slidably connected to a centering block. A hanging spring is arranged between two adjacent centering blocks on the same circumference. A first piston and a return spring are arranged between the bottom of the inclined groove at the lowest end of the center shaft and the bottom of the centering and tensioning housing. The lower end of the center shaft extends into the drive assembly and is connected to the upper piston. The lower piston of the drive assembly is connected to the piston rod of the hydraulic unit.

[0005] In the above scheme, the hydraulic unit includes a second piston, a piston rod, a hydraulic spring, a piston cylinder, and a hydraulic housing. The two ends of the piston cylinder are sealed by a cover. Each cover is bolted to the front end of a piston. The piston cylinder is set in the hydraulic housing through the front end of the piston. The second piston and piston rod are set in the piston cylinder. The two ends of the second piston have piston seals. A hydraulic spring is set between the piston seal at the upper end of the second piston and the cover at the upper end of the piston cylinder. The hydraulic spring surrounds the piston rod.

[0006] In the above scheme, three tensioning holes are evenly arranged circumferentially on the upper part of the straightening shell. There are three tensioning pads. The corresponding shoulders of the tensioning pads and the central shaft are hinged by connecting rods and pins. When the tensioning pads move to the highest position, they achieve the tensioning function. When they move to the lowest position, they fit tightly with the straightening tensioning shell.

[0007] The above scheme includes knurling on the surface of the tensioned roof tiles.

[0008] In the above scheme, the lower part of the straightening and tensioning shell is provided with two rings of straightening holes, each ring having three straightening holes. A slanted groove is provided at the position corresponding to the straightening hole on the central axis. A square groove is opened in each slanted groove. A straightening block is slidably connected to each slanted groove through the square groove. The straightening block has a sliding head. There is a gap between the straightening block and the straightening and tensioning shell, which is used to control the movement of the straightening block within the vertical range of the straightening and tensioning shell.

[0009] In the above scheme, the straightening block has a circular groove, the circular hoop is placed in the circular groove, and the inside of the circular groove has a groove that fits the circular hoop. The two ends of the hanging spring between two adjacent straightening blocks on the same circumference are connected to the circular hoop, so that all straightening blocks and circular hoops on the same circumference move synchronously, so that the entire structure is in the center position and the friction generated during forward movement is reduced.

[0010] In the above scheme, the end caps at both ends of the tensioning shell are threadedly connected to the shell cylinder, and the end caps have sealing grooves. Beneficial effects

[0011] 1. The traction device of this invention adopts a set of double piston rod hydraulic cylinders, which shortens the traction cycle and speeds up the traction speed compared with telescopic cylinders.

[0012] 2. The traction device of this invention is hydraulically driven, which is simpler in structure than wheeled traction devices and has greater traction force and more reliable traction than electric traction devices. It can effectively solve the problem of high resistance in coiled tubing operations and improve drilling efficiency.

[0013] 3. This invention adopts the method of first straightening and then tightening, and the tightening movement height is adaptive according to different drilling sizes, which is applicable to drilling of various sizes and has a wide range of applications. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the traction device in this invention; Figure 2 This is a cross-sectional view of the overall structure of the traction device in this invention; Figure 3 This is an enlarged view of the tensioning and straightening unit of the present invention; Figure 4 This is an overall structural appearance diagram of the present invention; Figure 5 yes Figure 2 Sectional view of AA in the middle; Figure 6 yes Figure 2 Cross-sectional view of the middle section (BB); Figure 7 This is an isometric view of the outer structure of the present invention; Figure 8 This is an isometric view of the internal structure of the present invention; In the diagram: 1-Central shaft; 2-End cap; 3-First piston; 4-Tensioning bearing; 5-Pin; 7-Connecting rod; 8-Centering block; 9-Hanging spring; 10-Sealing washer; 11-Reset spring; 12-Piston front end; 13-Screw; 14-Hydraulic housing; 15-Cover; 16-Hydraulic spring; 17-Piston cylinder; 18-Second piston; 19-Piston seal; 20-Piston rod; 21-Ring; 22-Drive assembly. Detailed Implementation

[0015] Combination Figures 1-8 As shown, this coiled tubing puller consists of a first puller and a second puller, which are symmetrically installed inside the well. Because this invention features a symmetrical distribution, Figure 1 Only half of the diagram is shown to facilitate a detailed demonstration of the internal structure. This invention only considers structural design; specific hydraulic aspects are not within the scope of this design and will not be explored in depth.

[0016] In this invention, each traction device includes a straightening and tensioning unit, a drive assembly 22, and a hydraulic unit connected in sequence. The straightening and tensioning unit includes a central shaft 1, multiple tensioning pads 4, multiple straightening blocks 8, a first piston 3, and a straightening and tensioning housing. The central shaft 1 passes through the straightening and tensioning housing. Tensioning holes are evenly arranged on the upper part of the straightening and tensioning housing, and straightening holes are arranged in a circle on the lower part of the straightening and tensioning housing. Shoulders and linkage mechanisms are evenly arranged circumferentially at positions corresponding to the tensioning holes on the central shaft 1. The tensioning pads are hinged to the shoulders through the linkage mechanism. The tensioning pads 4 are knurled on their surfaces. A set of inclined grooves is evenly arranged at the corresponding positions of the central shaft 1 and the straightening hole. Each inclined groove is slidably connected to a straightening block 8. A hanging spring 9 is set between two adjacent straightening blocks 8 on the same circumference. A first piston 3 and a return spring 11 are set between the bottom of the inclined groove at the lowest end of the central shaft 1 and the bottom of the straightening tension housing. The first piston 3 is loosely fitted on the central shaft 1 and arranged close to the shaft shoulder. The end caps 2 at the upper and lower ends of the straightening tension housing are threadedly connected to the housing cylinder. The end caps 2 have sealing grooves, and sealing gaskets 10 are set in the sealing grooves. The lower end of the central shaft 1 extends into the drive assembly and is connected to the upper piston. The lower piston of the drive assembly is connected to the piston rod 20 of the hydraulic unit. The return spring 11 is located between the first piston 3 and the bottom end cap of the straightening tension housing. The lower part of the annular space between the straightening tension housing and the central shaft 1 is the piston chamber.

[0017] In this embodiment, three tensioning holes are evenly arranged circumferentially on the upper part of the straightening shell. There are three tensioning pads 4, evenly distributed along a 60° circumference. The corresponding shoulders of the tensioning pads 4 and the central shaft 1 are hinged by the connecting rod 7 and the pin 5. The connecting rod 7 and the pin 5 constitute a linkage mechanism. When the tensioning pads 4 move to the highest position, the tensioning function is realized. When they move to the lowest position, they fit tightly with the straightening and tightening shell. Two rings of straightening holes are arranged at the lower part of the straightening and tightening shell, with three straightening holes in each ring. A slanted groove is provided at the corresponding position of the central shaft 1 and the straightening hole. Each slanted groove has a square groove. Each slanted groove is slidably connected to a straightening block 8 through the square groove. The straightening block 8 has a sliding head. The slanted groove is used to fix the path. There is a gap between the straightening block 8 and the straightening and tightening shell to control the movement of the straightening block within the vertical range of the straightening and tightening shell. The straightening block 8 has a circular groove, and the circular hoop 21 is placed in the circular groove. The inside of the circular groove has a groove that fits the circular hoop 21. The hanging spring 9 between two adjacent straightening blocks 8 on the same circumference is connected to the circular hoop 21 at both ends, so that all the straightening blocks 8 and circular hoops 21 on the same circumference keep moving synchronously, so that the whole structure is in the center position and the friction generated during forward movement is reduced.

[0018] The hydraulic unit includes a second piston 18, a piston rod 20, a hydraulic spring 16, a piston cylinder 17, and a hydraulic housing 14. The two ends of the piston cylinder 17 are closed by covers 15. Each cover 15 is connected to a piston front end 12 by screws 13. The piston cylinder 17 is disposed in the hydraulic housing 14 through the piston front end 12. The second piston 18 and the piston rod 20 are disposed in the piston cylinder 17. The two ends of the second piston 18 have piston seals 19. A hydraulic spring 16 is disposed between the piston seal 19 at the upper end of the second piston 18 and the cover 15 at the upper end of the piston cylinder 17. The hydraulic spring 16 surrounds the piston rod 20.

[0019] Work process: Hydraulic lines are installed inside the piston chamber and piston cylinder of the traction device in this application. Hydraulic switches are controlled by control elements to deliver hydraulic oil to each piston chamber and hydraulic unit, providing power to each hydraulic component and controlling the movement of the straightening and tensioning unit and the hydraulic unit. The technology for the specific hydraulic oil line layout and the rational design of the control elements is mature and will not be described in detail here.

[0020] During operation, the first and second traction devices are symmetrically installed inside the oil well. During operation, all hydraulic components are in their normal positions. First, oil is injected into the piston chamber of the centralizing and tensioning unit of the first traction device. The first piston 3 of the centralizing and tensioning unit drives the inclined groove on the central shaft 1 to move upwards. The centralizing block 8 works first; under the action of the circular hoop 21 and the hanging spring 9, the circumferentially arranged centralizing blocks 8 move synchronously. After the centralizing blocks 8 are pressed against the well wall, the entire traction device is centered. The tensioning bearing 4 then works. The tensioning bearing 4 has specially shaped grooves (i.e., knurling) to ensure tensioning efficiency. Under the action of hydraulic oil, the tensioning bearing 4 remains pressed against the well wall. At this time, the second piston 18 of the hydraulic unit of the second traction device is in the upper position. Oil is injected into its piston cylinder. Under the action of hydraulic oil, the second piston 18 of the hydraulic unit of the second traction device drives the piston rod 20 to slowly move downwards, completing one traction cycle. Under the action of the hydraulic spring 16, the second piston 18 of the first traction hydraulic unit returns to its normal position, preparing for the next traction stage.

[0021] Hydraulic oil is injected into the second traction unit's centering and tensioning unit. Under the action of the hydraulic oil, the first piston 3 drives the central shaft 1 downwards. Simultaneously, the centering block 8 rises, while the spring 9 remains taut. The centering block 8 presses firmly against the well wall, aligning the entire traction unit and coiled tubing in the center position. After the centering block 8 is in place, the tensioning bearing 4 on the central shaft 1 then operates. Under the action of hydraulic oil, the tensioning bearing 4 presses firmly against the well wall, and the second traction unit's centering and tensioning unit is ready to be positioned. After the second traction unit's centering and tensioning unit operates, the first piston 3 of the first traction unit's centering and tensioning unit, under the action of hydraulic oil, drives the central shaft 1 downwards, and the tensioning bearing 4 moves towards the well wall, ending the tensioning operation. Then, the centering block 8 also retracts to its normal position under the action of hydraulic oil, ending the centering operation. At this point, the first traction unit's centering and tensioning unit is in its initial position. When the second traction device straightening and tensioning unit is in working condition and the first traction device straightening and tensioning unit is in the initial position, hydraulic oil is input into the first traction device hydraulic unit. At this time, the second piston 18 of the first traction device hydraulic unit is in a high position. Under the action of the hydraulic oil, the second piston 18 of the first traction device hydraulic unit drives the piston rod 20 to move slowly downward, thus completing the second traction.

[0022] Subsequently, by controlling the centering and tensioning units at different positions and coordinating with the hydraulic unit, a certain motion cycle is completed, repeating continuously, thereby enabling the traction device to drive the continuous oil pipe to advance to the predetermined position.

[0023] During installation, the second piston 18 of the hydraulic unit is first fitted onto the piston rod 20, and then the second piston 18 is sealed using the piston seal 19. Next, a hydraulic spring 16 is fitted onto one side of the piston rod 20, and this entire assembly is then inserted into the piston 17. The side covers 15 and the piston front end 12 are fixed with screws 13. The aforementioned device is then inserted into the hydraulic housing 14, and the two sides of the hydraulic housing are tightened and fixed using end caps. Next, the straightening and tensioning unit is installed. The central shaft 1 is inserted into the straightening and tensioning housing 2, and the tensioning bearing 4 is fixed to the central shaft 1 using pins 5. The straightening block 8 is placed in the inclined groove of the central shaft. The left sides of the circular hoop 21 are first hinged together, and then the entire structure is fitted into the groove of the straightening block 8. The protrusions on the circular hoop 21 and the grooves of the straightening block 8 are tightly fitted together, and the circular hoop 21 is tightened in the groove of the straightening block using bolts. Finally, a special tool is used to hang the hanging spring 9 into the hole of the circular hoop. Next, install the other ring of straightening block 8, circular hoop 21, and hanging spring 9 according to the above steps. Then, loosely fit the first piston 3 on the side closest to the straightening block 8 onto the central shaft 1, and similarly, loosely fit the return spring 11 onto the central shaft 1 and place it close to the first piston 3. Then, tighten the end caps 2 on both sides of the outer casing through threaded connections.

Claims

1. A coiled tubing traction device, characterized in that: This coiled tubing tractor consists of a first tractor and a second tractor, which are symmetrically installed inside the well. Each tractor includes a centralizing and tensioning unit, a drive assembly, and a hydraulic unit connected in sequence. The centralizing and tensioning unit includes a central shaft, multiple tensioning bearings, multiple centralizing blocks, a first piston, and a centralizing and tensioning housing. The central shaft passes through the centralizing and tensioning housing. Tensioning holes are evenly arranged on the upper part of the centralizing and tensioning housing, and centralizing holes are arranged in a circle on the lower part. Shoulders and linkage mechanisms are evenly arranged circumferentially on the central shaft at positions corresponding to the tensioning holes. The tensioning bearings are hinged to the shoulders via the linkage mechanism. Inclined grooves are evenly arranged on the central shaft at positions corresponding to the centralizing holes. Each inclined groove slides to a centralizing block. A hanging spring is arranged between two adjacent centralizing blocks on the same circumference. A first piston and a return spring are arranged between the bottom of the inclined groove at the lowest end of the central shaft and the bottom of the centralizing and tensioning housing. The lower end of the central shaft extends into the drive assembly and is connected to the upper piston. The lower piston of the drive assembly is connected to the piston rod of the hydraulic unit.

2. The coiled tubing traction device according to claim 1, characterized in that: The hydraulic unit includes a second piston, a piston rod, a hydraulic spring, a piston cylinder, and a hydraulic housing. The two ends of the piston cylinder are sealed by caps, and each cap is bolted to the front end of a piston. The piston cylinder is located in the hydraulic housing through the front end of the piston. The second piston and piston rod are located in the piston cylinder. The two ends of the second piston have piston seals. A hydraulic spring is installed between the piston seal at the upper end of the second piston and the cap at the upper end of the piston cylinder. The hydraulic spring surrounds the piston rod.

3. The coiled tubing traction device according to claim 2, characterized in that: The upper part of the straightening shell is evenly provided with three tensioning holes along the circumference. There are three tensioning pads. The corresponding shoulders of the tensioning pads and the central shaft are hinged by connecting rods and pins. When the tensioning pads move to the highest position, they achieve the tensioning function. When they move to the lowest position, they fit tightly with the straightening tensioning shell.

4. The coiled tubing traction device according to claim 3, characterized in that: The surface of the tensioning tile is knurled.

5. The coiled tubing traction device according to claim 4, characterized in that: The lower part of the straightening and tensioning shell is provided with two rings of straightening holes, with three straightening holes in each ring. A slanted groove is provided at the position corresponding to the straightening hole on the central axis. A square groove is opened in each slanted groove. A straightening block is slidably connected to each slanted groove through the square groove. The straightening block has a sliding head. There is a gap between the straightening block and the straightening and tensioning shell, which is used to control the movement of the straightening block within the vertical range of the straightening and tensioning shell.

6. The coiled tubing traction device according to claim 5, characterized in that: The straightening block has a circular groove, and a circular hoop is placed in the circular groove. The inside of the circular groove has a groove that fits the circular hoop. The two ends of the hanging spring between two adjacent straightening blocks on the same circumference are connected to the circular hoop, so that all straightening blocks and circular hoops on the same circumference move synchronously, reducing the friction generated when moving forward.

7. The coiled tubing traction device according to claim 6, characterized in that: The end caps at the upper and lower ends of the tensioning shell are threadedly connected to the shell cylinder, and the end caps have sealing grooves.

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