Hydraulically controlled hydraulic drive coiled tubing tractor

Abstract

The application provides a liquid-controlled hydraulic drive coiled tubing tractor. The application is used to solve the problem of complex structure and low control stability of the existing tractor. The application comprises a central pipe, first, second and third piston cylinders arranged on the central pipe in sequence along the length direction of the central pipe, link support mechanisms arranged on the ends of the first and third piston cylinders away from the second piston cylinder, the first and third piston cylinders used for controlling the folding and unfolding of the two groups of link support mechanisms alternately, the first and second piston cylinders mounted on the central pipe, the third piston cylinder mounted on the piston rod of the second piston cylinder, a liquid-controlled drive assembly mounted on the outer wall of the central pipe and used for controlling the movement of the first, second and third piston cylinders, and a drilling fluid inlet formed on the side wall of the central pipe and communicated with the liquid inlet end of the liquid-controlled drive assembly. The application uses a single telescopic hydraulic cylinder to shorten the traction period and accelerate the traction speed. In addition, the traction process of the tractor only needs to control the pressure of the drilling fluid, and the system is stable and high in operation.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well engineering, and in particular to a hydraulically controlled coiled tubing traction device. Background Technology

[0002] In oil exploration and development, coiled tubing technology is widely used due to its high efficiency and flexibility. However, this technology has several problems: First, the small wellbore diameter and the lack of rotation of the coiled tubing make it difficult to carry cuttings downhole, leading to increased friction. Second, the small diameter and low material strength of the coiled tubing result in significant friction between the tubing and the wellbore when it is slidably fed into the bottom drill string assembly. When the axial pressure applied to the coiled tubing is less than the friction between the tubing and the wellbore, the coiled tubing is prone to buckling and self-locking, making it difficult to run downhole. This is especially true when drilling highly deviated wells, directional wells, horizontal wells, and deep wells, where the extension length is limited, hindering the widespread application of coiled tubing drilling technology. Currently, coiled tubing drilling technology is commonly used in directional well drilling operations with low axial friction or milling operations with low drilling pressure, such as drilling bridge plugs, and its application in horizontal wells is relatively rare. To improve the extension capability of coiled tubing horizontal wells, research on friction-reducing tools and processes has been conducted abroad. However, the extension length remains limited, and conventional friction-reducing technologies can no longer effectively solve the technical challenge of extending coiled tubing horizontal wells. Unlike conventional technologies, coiled tubing pullers prevent downhole tools from buckling and locking by providing axial tension to the coiled tubing, thereby increasing the extension length of coiled tubing horizontal wells.

[0003] Currently, commonly used traction devices can be generally divided into three types based on their structural design and movement method: First, wheeled traction devices, which press the drive wheel against the casing by tensioning the tensioning arm, and rely on the continuous rotation of the drive wheel to drive the traction device forward; second, tracked traction devices, which rely on the friction of the tracks on both sides of the body to drive the robot to move; and third, telescopic traction devices, which use two sets of alternating opening and closing grippers to alternately open and close the gripper and close the release mechanism of the casing or well wall, while the thruster continuously advances and resets, providing continuous traction force. Telescopic traction devices are classified into electrically controlled and hydraulically controlled types according to their control method, and into hydraulically driven and electrically driven types according to their drive method. Because it is difficult to run cables downhole in large-displacement horizontal wells, and long cables occupy valuable downhole space, have unstable signal transmission, and are prone to downhole accidents, hydraulically controlled devices have a wider range of applications and greater advantages than electrically controlled and electrically driven devices. Currently, most telescopic traction devices adopt a double telescopic cylinder structure design, which has a relatively large length, limited ability to pass through curved well sections, and the double telescopic structure results in a longer single traction cycle and slower traction speed. Furthermore, hydraulically controlled drive systems suffer from technical problems such as complex structure and low control stability. Summary of the Invention

[0004] The purpose of this invention is to provide a hydraulically controlled continuous tubing traction device. This addresses the technical problems of existing traction devices having complex structures and low control stability.

[0005] A hydraulically controlled coiled tubing traction device includes a central tube and first, second and third piston cylinders sequentially arranged on the central tube along its length.

[0006] Both the first and third piston cylinders are provided with a connecting rod support mechanism at the end away from the second piston cylinder. The first and third piston cylinders are used to control the two sets of connecting rod support mechanisms to alternately fold and unfold.

[0007] The first and second piston cylinders are mounted on the central tube, and the third piston cylinder is mounted on the piston rod of the second piston cylinder. A hydraulic control drive assembly for controlling the movement of the first, second, and third piston cylinders is installed on the outer wall of the central tube. A drilling fluid inlet is provided on the side wall of the central tube, and the drilling fluid inlet is connected to the inlet end of the hydraulic control drive assembly.

[0008] Optionally, a return spring is provided in the cylinder body of both the first and third piston cylinders at the end away from the second piston cylinder.

[0009] Optionally, the hydraulic drive assembly includes a pressure switching valve, the output of which is connected to a first control module and a second control module respectively.

[0010] The first control module includes a first reset valve, a first sequence valve, and a first directional valve whose inlet and outlet are connected in sequence; the outlet of the first reset valve is also connected to the cylinder body of the first piston cylinder near the second piston cylinder, and the outlet of the first directional valve is connected to the cylinder body of the second piston cylinder.

[0011] The second control module includes a second reset valve, a second sequence valve, and a second directional valve whose inlet and outlet are connected in sequence. The outlet of the second reset valve is also connected to the cylinder body of the third piston cylinder on the side close to the second piston cylinder, and the outlet of the second directional valve is connected to the cylinder body on the other side of the second piston cylinder.

[0012] Optionally, the liquid outlet of the first sequence valve is also connected to a control terminal of the first reversing valve, the second reset valve, and the second reversing valve.

[0013] The outlet of the second sequence valve is also connected to another control terminal of the first and second directional valves and one control terminal of the first reset valve.

[0014] Optionally, a first stroke valve and a second stroke valve are respectively installed in the cylinder bodies on both sides of the second piston cylinder;

[0015] The outlet of the first directional valve is also connected to the inlet of the first stroke valve, the outlet of the first stroke valve is connected to another control terminal of the second reset valve, the outlet of the second directional valve is also connected to the inlet of the second stroke valve, and the outlet of the second stroke valve is connected to another control terminal of the first reset valve.

[0016] Optionally, the first reset valve, the first sequence valve, the first directional valve, the second reset valve, and the second directional valve are all two-position three-way valves.

[0017] Optionally, the linkage support mechanism includes a support arm and a support base mounted on the outer wall of the central tube;

[0018] The support arm is connected to the support base via a driven link, and the support arm is connected to the piston rods of the first and third piston cylinders via a drive link. Both ends of the driven link and the drive link are hinged.

[0019] Optionally, the first piston cylinder includes a first cylinder body and a first piston rod, wherein a first piston head is mounted on one end of the first piston rod located inside the first cylinder body;

[0020] The first piston head slides along the inner wall of the first cylinder. Both ends of the first cylinder are mounted on the outer wall of the central tube. The first piston rod and the first piston head are slidably sleeved on the outer wall of the central tube. The return spring is sleeved on the outer wall of the first piston rod inside the first cylinder. The connecting rod support mechanism is located at the end of the first piston rod that extends out of the first cylinder.

[0021] Optionally, the second piston cylinder includes a second cylinder body and a second piston rod, wherein a second piston head is mounted on one end of the second piston rod located inside the second cylinder body;

[0022] The second piston head slides along the inner wall of the second cylinder. Both ends of the second cylinder are mounted on the outer wall of the central tube. The second piston rod and the second piston head are both slidably sleeved on the outer wall of the central tube. The end of the second piston rod near the third piston cylinder extends out of the second cylinder. The third piston cylinder is mounted on the second piston rod.

[0023] Optionally, the third piston cylinder includes a third cylinder body and a third piston rod, wherein a third piston head is installed at one end of the third piston rod located inside the third cylinder body;

[0024] The third piston head slides along the inner wall of the third cylinder. The two ends of the third cylinder are mounted on the outer wall of the piston rod of the second piston cylinder. The third piston rod and the third piston head are both slidably sleeved on the outer wall of the piston rod of the second piston cylinder. The return spring is sleeved on the outer wall of the third piston rod inside the third cylinder. The connecting rod support mechanism is located at the end of the third piston rod that extends out of the third cylinder.

[0025] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0026] 1. The traction device of this application adopts a telescopic design, which is simpler in structure than wheeled traction devices, reduces maintenance risks caused by structural complexity, and lowers the possibility of accidents in complex downhole environments. In addition, the linkage support mechanism allows for a wider range of applicable pipe diameters for the traction device.

[0027] 2. This application adopts a single telescopic hydraulic cylinder structure design, which shortens the traction cycle and speeds up the traction speed compared to a double telescopic cylinder.

[0028] 3. In this application, the traction process of the traction device only needs to control the pressure of the drilling fluid, without the need for complex electromagnetic control and signal transmission. The system operates with high stability and fast response, avoiding delays caused by signal transmission, and has high traction efficiency.

[0029] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0030] The accompanying drawings of this invention are described below.

[0031] Figure 1 This is a schematic diagram of the structure of the coiled tubing traction device of the present invention.

[0032] Figure 2 This is a cross-sectional view of the coiled tubing traction device of the present invention.

[0033] Figure 3 For the present invention Figure 2 A magnified view of a portion of point A in the middle.

[0034] Figure 4 For the present invention Figure 2 A magnified view of a section at point B.

[0035] Figure 5 For the present invention Figure 2 A magnified view of a section at point C.

[0036] Figure 6 This is a diagram illustrating the traction process of the coiled tubing traction device of the present invention.

[0037] Figure 7 This is a drilling fluid flow diagram of the hydraulic control drive assembly of the present invention.

[0038] In the diagram: 1-Central tube; 101-Drilling fluid inlet; 2-First piston cylinder; 201-First cylinder body; 202-First piston rod; 203-First piston head; 204-First return spring; 205-Upper hydraulic cylinder end cap; 206-Upper base; 3-Second piston cylinder; 301-Second cylinder body; 302-Second piston rod; 303-Second piston head; 4-Third piston cylinder; 401-Third cylinder body; 402-Third piston rod; 403-Third piston head; 404-Second return spring ; 405-Lower hydraulic cylinder end cap; 406-Lower base; 5-Linkage support mechanism; 501-Support arm; 502-Support base; 503-Driven linkage; 504-Drive linkage; 6-Hydraulic control drive assembly; 601-Pressure switch valve; 602-First reset valve; 603-First sequence valve; 604-First directional valve; 605-Second reset valve; 606-Second sequence valve; 607-Second directional valve; 608-First stroke valve; 609-Second stroke valve; 610-Filter. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] Example 1:

[0041] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 The hydraulically controlled continuous tubing tractor shown includes a central tube 1, and a first piston cylinder 2, a second piston cylinder 3 and a third piston cylinder 4 arranged sequentially along the length of the central tube 1.

[0042] Both the first piston cylinder 2 and the third piston cylinder 4 are provided with a connecting rod support mechanism 5 at the end away from the second piston cylinder 3. The first piston cylinder 2 and the third piston cylinder 4 are used to control the two sets of connecting rod support mechanisms 5 to alternately open and close.

[0043] The first piston cylinder 2 and the second piston cylinder 3 are mounted on the central tube 1, and the third piston cylinder 4 is mounted on the piston rod of the second piston cylinder 3. A hydraulic control drive assembly 6 for controlling the movement of the first piston cylinder 2, the second piston cylinder 3 and the third piston cylinder is mounted on the outer wall of the central tube 1. A drilling fluid inlet 101 is provided on the side wall of the central tube 1, and the drilling fluid inlet 101 is connected to the inlet end of the hydraulic control drive assembly 6.

[0044] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, the first piston cylinder 2 includes a first cylinder body 201 and a first piston rod 202, and a first piston head 203 is installed at one end of the first piston rod 202 located inside the first cylinder body 201.

[0045] The first piston head 203 slides along the inner wall of the first cylinder 201. Both ends of the first cylinder 201 are mounted on the outer wall of the central tube 1. The first piston rod 202 and the first piston head 203 are both slidably sleeved on the outer wall of the central tube 1. A first return spring 204 is sleeved on the outer wall of the first piston rod 202. The first return spring 204 is located inside the first cylinder 201. The connecting rod support mechanism is located at the end of the first piston rod 202 that extends out of the first cylinder 201.

[0046] In this embodiment, the first cylinder body 201 is attached to a boss of the central tube 1 by screws at one end near the second piston cylinder 3. The other end of the first cylinder body 201 is equipped with an upper hydraulic cylinder end cover 205 and an upper base 206. The first piston rod 202 slides through the upper hydraulic cylinder end cover 205 and the upper base 206. An O-ring is provided between the upper hydraulic cylinder end cover 205 and the side wall of the first cylinder body 201.

[0047] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the second piston cylinder includes a second cylinder body 301 and a second piston rod 302, and a second piston head 303 is installed at one end of the second piston rod 302 located inside the second cylinder body 301.

[0048] The second piston head 303 slides along the inner wall of the second cylinder 301. The two ends of the second cylinder 301 are mounted on the outer wall of the central tube 1. The second piston rod 302 and the second piston head 303 are both slidably sleeved on the outer wall of the central tube 1. The end of the second piston rod 302 near the third piston cylinder 4 extends out of the second cylinder 301.

[0049] In this embodiment, a placement cavity is provided at the end of the second cylinder 301 near the first piston cylinder 2, and the hydraulic drive assembly 6 is disposed in the placement cavity. The end of the second cylinder 301 near the first piston cylinder 2 is attached to another protrusion of the central tube 1 by screws. A telescopic hydraulic cylinder end cover 304 is installed at the end of the second cylinder 301 near the third piston cylinder 4. The second piston rod 302 slides through the telescopic hydraulic cylinder end cover 304, and an O-ring is provided between the second piston rod 302 and the telescopic hydraulic cylinder end cover 304.

[0050] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the third piston cylinder 4 includes a third cylinder body 401 and a third piston rod 402, and a third piston head 403 is installed at one end of the third piston rod 402 located inside the third cylinder body 401.

[0051] The third piston head 403 slides along the inner wall of the third cylinder 401. The two ends of the third cylinder 401 are mounted on the outer wall of the piston rod of the second piston cylinder 3. The third piston rod 402 and the third piston head 403 are both slidably sleeved on the outer wall of the piston rod of the second piston cylinder 3. A second return spring 404 is sleeved on the outer wall of the third piston rod 401. The second return spring 404 is located inside the third cylinder 401. The connecting rod support mechanism is located at the end of the third piston rod 402 that extends out of the third cylinder 401.

[0052] In this embodiment, one end of the third cylinder 401 near the second piston cylinder 3 is screwed to a boss of the second piston rod 302. The other end of the third cylinder 401 is equipped with a lower hydraulic cylinder end cover 405 and a lower base 406. The third piston rod 402 slides through the lower hydraulic cylinder end cover 405 and the lower base 406. An O-ring is provided between the lower hydraulic cylinder end cover 405 and the side wall of the third cylinder 401.

[0053] In this embodiment, through holes are formed on the sidewalls of the first cylinder 201 and the third cylinder 401 where the return spring is located. Gas in the well passage enters the cavities of the first cylinder 201 and the third cylinder 401 where the return spring is located through the through holes. The cylinder body of the first piston cylinder 2 without the return spring is defined as the first hydraulic chamber, the cylinder body of the third piston cylinder 4 without the return spring is defined as the second hydraulic chamber, the cylinder body of the second piston cylinder 3 near the first piston cylinder 2 is defined as the third hydraulic chamber, and the cylinder body of the second piston cylinder 3 near the third piston cylinder 4 is defined as the fourth hydraulic chamber.

[0054] like Figure 6As shown in (a)-6(e), the specific steps of the traction device are as follows: S1: The hydraulic control drive assembly 6 fills the first hydraulic chamber with fluid, the connecting rod support mechanism 5 at one end of the first piston cylinder 2 opens to contact the well wall, and at the same time, the second hydraulic chamber is depressurized, and the connecting rod support mechanism 5 at one end of the third piston cylinder 3 folds up and does not contact the well wall; S2: The hydraulic control drive assembly 6 fills the third hydraulic chamber with fluid, pushing the second piston rod 302, the third piston cylinder 4 and the connecting rod support mechanism 5 at the front end of the third piston cylinder 4 downward; S3: The hydraulic control drive assembly 6 fills the second hydraulic chamber with fluid, and the connecting rod support mechanism 5 at the front end of the third piston cylinder 4 opens to contact the well wall; S4: The first hydraulic chamber is depressurized, and the connecting rod support mechanism 5 at one end of the first piston cylinder 2 folds up and does not contact the well wall; S5: The hydraulic control drive assembly 6 fills the fourth hydraulic chamber with fluid, pulling the second cylinder 301, the first piston cylinder 2 and the connecting rod support mechanism 5 at the front end of the first piston cylinder downward; Repeat steps S1-S5 to achieve forward traction of the traction device.

[0055] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the linkage support mechanism 5 includes a support arm 501 and a support base 502 installed on the outer wall of the central tube 1;

[0056] The support arm 501 is connected to the support base 502 via a driven link 503, and the support arm 501 is connected to the first piston rod 202 and the third piston rod 402 via a drive link 504. Both ends of the driven link 503 and the drive link 504 are hinged.

[0057] In this embodiment, the support base 502 is fixedly installed on the central tube 1, and both the first piston rod 202 and the third piston rod 402 slide through the support base 502. When the first piston rod 202 or the third piston rod 402 is pushed out, under the action of the driven connecting rod 503 and the driving connecting rod 504, the support arm 501 abuts against the well wall, achieving support at one end. The linkage support mechanism 5 of this application can achieve support for wellbore of any width within its stroke width, and has a wide range of applications.

[0058] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the hydraulic control drive assembly 6 includes a pressure switch valve 601, and the output end of the pressure switch valve 601 is respectively connected to a first control module and a second control module.

[0059] The first control module includes a first reset valve 602, a first sequence valve 603, and a first directional valve 604, whose inlet and outlet are connected in sequence; the outlet of the first reset valve 602 is also connected to a first hydraulic chamber, and the outlet of the first directional valve 604 is connected to a third hydraulic chamber.

[0060] The second control module includes a second reset valve 605, a second sequence valve 606, and a second directional valve 607, whose inlet and outlet ends are connected in sequence. The outlet end of the second reset valve 605 is also connected to the second hydraulic chamber, and the outlet end of the second directional valve 607 is connected to the fourth hydraulic chamber.

[0061] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, a first stroke valve 608 and a second stroke valve 609 are respectively installed in the cylinder bodies on both sides of the second piston cylinder 3.

[0062] The outlet of the first directional valve 604 is also connected to the inlet of the first stroke valve 608. The outlet of the first stroke valve 608 is connected to another control terminal of the second reset valve 605. The outlet of the second directional valve 607 is also connected to the inlet of the second stroke valve 609. The outlet of the second stroke valve 609 is connected to another control terminal of the first reset valve 602.

[0063] In this embodiment, the first reset valve 602, the first reversing valve 604, the second reset valve 605, and the second reversing valve 607 are all two-position three-way valves, each equipped with a pressure relief port. The conduction pressure of the pressure switch valve 601 is P0, and the conduction pressure of the first sequence valve 603 and the second sequence valve 606 is P1. A filter 610 is provided at the front end of the pressure switch valve 601. When the traction device moves forward, such as Figure 7 (a)- Figure 7 (h) shows ( Figure 7 The red line in the middle indicates the drilling fluid flow direction. The specific steps are as follows:

[0064] S1: Control the drilling fluid pressure in the central pipe 1 to make it greater than P0, the pressure switch valve 601 is turned on, and the drilling fluid enters the first hydraulic chamber through the filter 610, the pressure switch valve 601 and the first reset valve 602 (the inlet and outlet of the first reset valve 602 are turned on at the initial moment), so that the connecting rod support mechanism 5 at the front end of the first piston cylinder 2 is opened and comes into contact with the well wall.

[0065] S2: When the connecting rod support mechanism 5 at the front end of the first piston cylinder 2 is opened and comes into contact with the well wall, the pressure at the inlet end of the first sequence valve 603 rises. When it is greater than P1, the first sequence valve 603 is opened.

[0066] The drilling fluid pushes the first directional valve 604 to switch direction through the control terminal of the first directional valve 604, and the inlet and outlet of the first directional valve 604 are connected; at the same time, the drilling fluid pushes the second reset valve 605 and the second directional valve 607 to switch direction through the control terminals of the second reset valve 605 and the second directional valve 607, so that their inlet and outlet are not connected, and their outlet is connected to the pressure relief end. Under the action of the second reset spring 404, the second hydraulic chamber is depressurized through the second reset valve 605.

[0067] S3: Drilling fluid enters the third hydraulic chamber through the inlet and outlet of the first directional valve 604, while the fourth hydraulic chamber is depressurized through the second directional valve 607.

[0068] S4: When the second piston head 303 moves to the end of its stroke, it pushes the first stroke valve 608 to open, and the drilling fluid passes through the first stroke valve 608 to the control end of the second reset valve 605 to push it to move, so that the inlet and outlet of the second reset valve 605 are connected.

[0069] S5: Drilling fluid enters the second hydraulic chamber through the inlet and outlet of the second reset valve 605, causing the connecting rod support mechanism 5 at the front end of the third piston cylinder 4 to open and contact the well wall.

[0070] S6: When the connecting rod support mechanism 5 at the front end of the third piston cylinder 4 is opened and comes into contact with the well wall, the pressure at the inlet end of the second sequence valve 606 rises. When it is greater than P1, the second sequence valve 606 is opened.

[0071] The drilling fluid pushes the second directional valve 607 to switch direction through the control terminal of the second directional valve 607, and the inlet and outlet ends of the second directional valve 607 are connected; at the same time, the drilling fluid pushes the first reset valve 602 and the first directional valve 604 to switch direction through the control terminals of the first reset valve 602 and the first directional valve 604, so that their inlet and outlet ends are not connected, and their outlet end is connected to the pressure relief end. Under the action of the first reset spring 204, the first hydraulic chamber is depressurized through the first reset valve 602.

[0072] S7: Drilling fluid enters the fourth hydraulic chamber through the inlet and outlet of the second directional valve 607, while the third hydraulic chamber is depressurized through the first directional valve 604.

[0073] S8: When the second piston head 303 moves to the end of its other stroke, it pushes the second stroke valve 609 to open, and the drilling fluid passes through the second stroke valve 609 to the control end of the first reset valve 602 to push it to move, so that the inlet and outlet of the first reset valve 602 are connected.

[0074] S9: Repeat steps S1-S8 to achieve forward traction of the traction device.

[0075] In this application, the traction process of the traction device only requires controlling the pressure of the drilling fluid, without the need for complex electromagnetic control and signal transmission. The system operates with high stability and fast control response, avoiding delays caused by signal transmission and achieving high traction efficiency.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A hydraulically controlled coiled tubing traction device, characterized in that, It includes a central tube, and first, second and third piston cylinders arranged sequentially on the central tube along its length. Both the first and third piston cylinders are provided with a connecting rod support mechanism at the end away from the second piston cylinder. The first and third piston cylinders are used to control the two sets of connecting rod support mechanisms to alternately fold and unfold. The first and second piston cylinders are mounted on the central tube, and the third piston cylinder is mounted on the piston rod of the second piston cylinder. A hydraulic control drive assembly for controlling the movement of the first, second, and third piston cylinders is mounted on the outer wall of the central tube. A drilling fluid inlet is provided on the side wall of the central tube, and the drilling fluid inlet is connected to the inlet end of the hydraulic control drive assembly. The hydraulic control drive assembly includes a pressure switching valve, and the output end of the pressure switching valve is respectively connected to a first control module and a second control module. The first control module includes a first reset valve, a first sequence valve, and a first directional valve whose inlet and outlet are connected in sequence; the outlet of the first reset valve is also connected to the cylinder body of the first piston cylinder near the second piston cylinder, and the outlet of the first directional valve is connected to the cylinder body of the second piston cylinder. The second control module includes a second reset valve, a second sequence valve, and a second directional valve whose inlet and outlet are connected in sequence. The outlet of the second reset valve is also connected to the cylinder body of the third piston cylinder on the side close to the second piston cylinder, and the outlet of the second directional valve is connected to the cylinder body on the other side of the second piston cylinder.

2. The hydraulically controlled continuous tubing traction device according to claim 1, characterized in that, Both the first and third piston cylinders have a return spring installed in the cylinder body at the end furthest from the second piston cylinder.

3. The hydraulically controlled continuous tubing traction device according to claim 1, characterized in that, The liquid outlet of the first sequence valve is also connected to a control terminal of the first reversing valve, the second reset valve, and the second reversing valve. The outlet of the second sequence valve is also connected to another control terminal of the first and second directional valves and one control terminal of the first reset valve.

4. A hydraulically controlled continuous tubing traction device according to claim 3, characterized in that, The second piston cylinder has a first stroke valve and a second stroke valve installed in the cylinder bodies on both sides, respectively. The outlet of the first directional valve is also connected to the inlet of the first stroke valve, the outlet of the first stroke valve is connected to another control terminal of the second reset valve, the outlet of the second directional valve is also connected to the inlet of the second stroke valve, and the outlet of the second stroke valve is connected to another control terminal of the first reset valve.

5. A hydraulically controlled coiled tubing traction device according to claim 4, characterized in that, The first reset valve, the first sequence valve, the first directional valve, the second reset valve, and the second directional valve are all two-position three-way valves.

6. A hydraulically controlled coiled tubing traction device according to claim 1, characterized in that, The linkage support mechanism includes a support arm and a support base installed on the outer wall of the central tube; The support arm is connected to the support base via a driven link, and the support arm is connected to the piston rods of the first and third piston cylinders via a drive link. Both ends of the driven link and the drive link are hinged.

7. A hydraulically controlled continuous tubing traction device according to claim 2, characterized in that, The first piston cylinder includes a first cylinder body and a first piston rod, wherein a first piston head is installed at one end of the first piston rod located inside the first cylinder body; The first piston head slides along the inner wall of the first cylinder. Both ends of the first cylinder are mounted on the outer wall of the central tube. The first piston rod and the first piston head are slidably sleeved on the outer wall of the central tube. The return spring is sleeved on the outer wall of the first piston rod inside the first cylinder. The connecting rod support mechanism is located at the end of the first piston rod that extends out of the first cylinder.

8. A hydraulically controlled continuous tubing traction device according to claim 1 or 2, characterized in that, The second piston cylinder includes a second cylinder body and a second piston rod, wherein a second piston head is mounted on one end of the second piston rod located inside the second cylinder body; The second piston head slides along the inner wall of the second cylinder. Both ends of the second cylinder are mounted on the outer wall of the central tube. The second piston rod and the second piston head are both slidably sleeved on the outer wall of the central tube. The end of the second piston rod near the third piston cylinder extends out of the second cylinder. The third piston cylinder is mounted on the second piston rod.

9. A hydraulically controlled continuous tubing traction device according to claim 2, characterized in that, The third piston cylinder includes a third cylinder body and a third piston rod, and a third piston head is installed at one end of the third piston rod located inside the third cylinder body. The third piston head slides along the inner wall of the third cylinder. The two ends of the third cylinder are mounted on the outer wall of the piston rod of the second piston cylinder. The third piston rod and the third piston head are both slidably sleeved on the outer wall of the piston rod of the second piston cylinder. The return spring is sleeved on the outer wall of the third piston rod inside the third cylinder. The connecting rod support mechanism is located at the end of the third piston rod that extends out of the third cylinder.

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