CN112065312A - Hydraulic telescopic coiled tubing tractor for dense gas operation and use method - Google Patents

Abstract

The invention provides a hydraulic telescopic coiled tubing tractor for dense gas operation and a use method thereof. According to the invention, the dovetail sliding blocks and the wedge-shaped dovetail sliding blocks are in sliding connection through the tooth-shaped sliding grooves and the protrusions, and the tooth-shaped groove structure can better provide arm-grabbing force and provide large traction force; the invention avoids the phenomenon that the tractor is blocked when meeting the underground concave-convex soft points; meanwhile, the capacity of assisting the coiled tubing and related downhole tools to go out of the well after the operation is finished is met, and the two-way obstacle crossing function is achieved.

Description

Hydraulic telescopic coiled tubing tractor for dense gas operation and use method

Technical Field

The invention relates to a tractor for horizontal well section downhole operation, belongs to the field of downhole tools in the petroleum industry, and particularly relates to a hydraulic telescopic coiled tubing tractor for dense gas operation and a using method thereof.

Background

The petroleum and natural gas are important strategic resources, are widely distributed in China and have high development difficulty, and the development of using a horizontal well is a novel and effective technology for compact oil and gas reservoirs. At the present stage, in order to reduce the exploitation cost and improve the recovery efficiency of oil and gas fields, a horizontal drilling technology is mostly adopted, and an instrument is often required to be lowered to the underground for logging, well repairing, conveying underground tools and the like. However, due to the special nature of horizontal wells, the conventional gravity-fed cable-suspended manner cannot feed downhole tools to the horizontal section. The feeding mode of adopting the flexible oil pipe has no advantages in cost and efficiency, and the transportation difficulty is increased correspondingly due to the increase of the size of the horizontal section. Therefore, a special traction device needs to be designed, and the traction device can pull the tool to move forwards by means of the traction force provided by the traction device, so that the related work requirement is met.

Through the development of more than ten years recently, the structure of the horizontal well tractor is continuously improved, and various tractors are formed, and the horizontal well tractor can be divided into the following traction modes in terms of the driving modes: wheeled tractor, telescopic tractor, crawler tractor. Despite the maturation of downhole tractor technology over the past decade, there are still many problems and issues to be improved.

At present, the design of the domestic tractor is still in the stages of theoretical research and design experiment, and the research result is immature. And since the foreign start is early, a large amount of products are put into practical production. In the aspect of traction force, the traction force of the underground tractor in the current domestic and foreign markets is below 1000kg, and only logging cables or light instruments can be pulled. In terms of driving mode, both telescopic tractors and wheel tractors adopt motor driving and screw nut transmission, so that although the design is simplified, the tractor structure is complex and the mechanical efficiency is reduced. Meanwhile, domestic and foreign tractors also have the defects of poor obstacle crossing capability and poor capability of adapting to casing diameter change or casing deformation.

Disclosure of Invention

The invention provides a hydraulic telescopic coiled tubing tractor for compact gas operation and a using method thereof, aiming at solving the problems that the existing tractor cannot pass in two directions, has weak adaptability and poor obstacle crossing capability.

The technical scheme adopted by the invention is as follows:

a hydraulic telescopic coiled tubing tractor for compact gas operation at least comprises an outer sleeve, coiled tubing, a joint component, two locking mechanisms, an oil discharge port sliding sleeve, a central tube, a telescopic reciprocating mechanism and a traction mechanism, wherein the two locking mechanisms comprise a left locking mechanism and a right locking mechanism; the coiled tubing is communicated with the central tube through a joint assembly; the outer sleeve comprises a left outer sleeve and a right outer sleeve, the left outer sleeve is provided with an oil discharge port A ', and the right outer sleeve is provided with an oil discharge port B'.

The connector assembly comprises a fishing neck, a locking slip, a sealing connector and an inclined connector, wherein the fishing neck is connected with the left end of the sealing connector through a trapezoidal thread, and the right end of the sealing connector is connected with the inclined connector through a trapezoidal thread; the external thread at the right end of the inclined joint is connected with the left outer sleeve, and the internal thread at the right end is connected with the left central tube; the locking slip is embedded in the fishing neck and sleeved on the coiled tubing, and the coiled tubing penetrates through the fishing neck and is connected with the sealing joint.

The left locking mechanism and the right locking mechanism are identical in structure, the left locking mechanism comprises a compression spring I, a left outer sleeve, a dovetail slide block retaining ring, a dovetail slide block and a wedge-shaped dovetail slide block, the right side of the wedge-shaped dovetail slide block is connected with an oil discharge port sliding sleeve, and the left side of the wedge-shaped dovetail slide block is connected with the dovetail slide block retaining ring; one end of the compression spring is fixed on the end face of the right side of the inclined joint, and the other end of the compression spring props against the dovetail slide block retainer ring; the dovetail sliding blocks are embedded on the wedge-shaped dovetail sliding blocks through wedge-shaped grooves at the bottoms; the contact surface of the dovetail sliding block and the wedge-shaped dovetail sliding block is an inclined surface, and a hole matched with the dovetail sliding block is formed in the left outer sleeve; an oil discharge port A' is arranged on the left outer sleeve and is positioned at the oil discharge port sliding sleeve; the oil inlet A is arranged on a central pipe positioned at the right side of the oil unloading port sliding sleeve.

The telescopic reciprocating mechanism comprises an inner piston sliding sleeve I, a hollow piston positioning baffle ring, a hollow piston and a clamping ring, the inner piston sliding sleeve I is sleeved on the central pipe, and the left end of the inner piston sliding sleeve I is fixedly connected with the oil discharge port sliding sleeve; the hollow piston positioning retaining ring is fixed in a groove at the left end of the inner piston sliding sleeve, one end of the hollow piston is sleeved into the inner piston sliding sleeve, the other end of the hollow piston is connected with the right outer sleeve, and the hollow piston can stretch and retract; the snap ring is fixed in a groove at the right end of the left central tube and limits the inner piston sliding sleeve.

The traction mechanism comprises an inner piston sliding sleeve II, a traction piston, a compression spring II, a traction sliding sleeve, a right central pipe and a right outer sleeve; the inner piston sliding sleeve II is sleeved between the right central pipe and the right outer sleeve, and the traction piston is sleeved between the inner piston sliding sleeve II and the traction sliding sleeve; a wedge-shapeddovetail slide block 9 in the right locking mechanism is connected with the left ends of the two inner piston sliding sleeves, and the traction sliding sleeve is connected with the right end part of the right central tube; the oil inlet B is arranged on the right central pipe at the second position of the inner piston sliding sleeve and is positioned at the left end of the traction piston; the oil outlet B' is arranged on the right outer sleeve at the traction sliding sleeve and is positioned at the lower part of the right outer sleeve; one end of the compression spring II is contacted with the bulge of the inner piston sliding sleeve II, and the other end of the compression spring II is propped against the traction sliding sleeve.

The traction sliding sleeve is of a hollow cylinder structure, the right end of the traction sliding sleeve is provided with an outer step hole, the left end of the traction sliding sleeve is provided with two inner step holes, and the step side surface of the inner step hole on the left side is connected with a sliding way; the right inner step hole is fixedly connected with the right end part of the right central tube; the diameter of the inner step hole on the left side is larger than that of the outer step hole, and the diameter of the outer step hole is larger than that of the inner step hole on the right side; and the second compression spring is supported on the step surface of the inner step hole on the left side.

The end parts of the two right ends of the inner piston sliding sleeve are provided with bulges which limit the traction sliding sleeve.

A use method of a hydraulic telescopic coiled tubing tractor for dense gas operation comprises the following specific steps:

when the oil inlet A works, oil is fed into the oil inlet A, the wedge-shaped dovetail sliding block pushes the dovetail sliding block to be in contact with a well wall and locked, meanwhile, the hollow piston extends out to reach an extension state, the inner piston sliding sleeve II is pushed to open the oil inlet B, and the extending position of the hollow piston is limited by the clamping ring; the oil inlet A and the oil inlet B simultaneously feed oil, when the hollow piston extends to a limit position, the oil discharge port A' is opened, and the wedge-shaped dovetail slide block is retracted under the action of a compression spring; the oil inlet B is filled with oil to enable the right locking mechanism to be locked, meanwhile, the traction piston is pushed to move right to reach a limit position, and then the right central tube is pulled to complete traction; after the tractor reaches the extreme position, the oil discharge port B' discharges oil, the right locking mechanism retracts, and the hydraulic telescopic coiled tubing tractor returns to the initial state.

The invention has the beneficial effects that:

the outer surfaces of dovetail slide blocks in the left locking mechanism and the right locking mechanism adopt a tooth-shaped groove structure, and the tooth-shaped groove structure can better provide arm-grasping force so as to improve the friction force between the obstacle crossing mechanism and a well wall and provide larger traction force; the tractor can effectively adapt to the complex underground environment to achieve the obstacle crossing function, and the phenomenon that the tractor is blocked when meeting underground concave-convex soft points is avoided; meanwhile, the capacity of assisting the coiled tubing and related downhole tools to go out of the well after the operation is finished is met, and the two-way obstacle crossing function is achieved.

Drawings

FIG. 1 is a schematic view of the structure of the present invention.

Fig. 2 is a schematic view of the locking mechanism.

FIG. 3 is a schematic view of a dovetail slide.

Fig. 4 is a schematic view of the telescoping mechanism.

Fig. 5 is a schematic view of the traction mechanism.

FIG. 6 is a schematic view of a wedge-shaped dovetail slide.

In the figures, the reference numbers are: 1. a coiled tubing; 2. fishing a neck; 3. locking slips; 4. sealing the joint; 5. an oblique joint; 6. a first compression spring; 7. a left side outer sleeve; 8. a dovetail slide block retainer ring; 9. a dovetail slide block; 10. a wedge-shaped dovetail slide block; 11. a first sealing ring; 12. a left center tube; 13. an oil discharge port sliding sleeve; 14. the inner piston is sleeved in a sliding sleeve I; 15. a hollow piston positioning baffle ring; 16. a second sealing ring; 17. a hollow piston; 18. a central tube; 19. a snap ring; 20. a limiting block; 21. a right side outer sleeve; 22. a right center tube; 23. an inner piston sliding sleeve II; 24. a third sealing ring; 25. a fourth sealing ring; 26. a second compression spring; 27. a traction sliding sleeve; 28. the piston is pulled.

Detailed Description

Example 1:

in order to solve the problems that the existing tractor cannot pass in two directions, is weak in adaptability and poor in obstacle crossing capability, the invention provides the hydraulic telescopic coiled tubing tractor for the dense gas operation and the use method thereof as shown in the figures 1-6.

A hydraulic telescopic coiled tubing tractor for compact gas operation at least comprises an outer sleeve, a coiled tubing 1, two joint components, two locking mechanisms, an oil dischargeport sliding sleeve 13, acentral tube 18, a telescopic reciprocating mechanism and a traction mechanism, wherein thecentral tube 18 is positioned in the outer sleeve, the joint components, the left locking mechanisms, the oil dischargeport sliding sleeve 13, the telescopic reciprocating mechanism, the right locking mechanism and the traction mechanism are sequentially connected and sleeved on thecentral tube 18, thecentral tube 18 comprises a leftcentral tube 12 and a rightcentral tube 22, the leftcentral tube 12 is provided with an oil inlet A, and the rightcentral tube 22 is provided with an oil inlet B; the coiled tubing 1 is communicated with acentral tube 18 through a joint assembly; the outer sleeve comprises a leftouter sleeve 7 and a rightouter sleeve 21, wherein an oil discharge port A 'is formed in the leftouter sleeve 7, and an oil discharge port B' is formed in the rightouter sleeve 21.

The working process of the invention is as follows:

during operation, the oil inlet A is filled with oil, the left locking mechanism is in contact with the well wall and locked, the telescopic reciprocating mechanism is in an extending state at the same time, the traction mechanism is pushed to slide rightwards, the oil inlet B is opened, the oil inlet A and the oil inlet B are filled with oil at the same time, the oil discharging port A' is opened when the telescopic reciprocating mechanism extends to a limit position, and the left locking mechanism is retracted; after the oil enters the oil inlet B, the right locking mechanism is locked, meanwhile, atraction piston 28 in the traction mechanism is pushed to move right to reach a limit position, and then the rightcentral tube 22 is pulled to complete traction; after the tractor reaches the extreme position, the oil discharge port B' discharges oil, the right locking mechanism retracts, and the hydraulic telescopic coiled tubing tractor returns to the initial state. In the invention, during operation, agap 20 is formed between the leftouter sleeve 7 and the rightouter sleeve 21 in a separated mode.

The invention can effectively adapt to complex underground environment to achieve the obstacle crossing function and avoid the phenomenon that the tractor is blocked when meeting underground concave-convex soft points; meanwhile, the capacity of assisting the coiled tubing and related downhole tools to go out of the well after the operation is finished is met, and the two-way obstacle crossing function is achieved. The invention can be used for shale gas or dense gas operation.

According to the invention, the oil discharge ports A ', the oil inlets A, the oil discharge ports B' and the oil inlets B are all multiple and are arranged circumferentially. In the invention, four oil inlets A and four oil inlets B are selected. The oil inlet is not necessarily circular.

The invention avoids the phenomenon that the tractor is stuck when meeting the underground concave-convex soft points, has good structural stability, is not easy to turn over laterally, and obviously improves the safety of the underground operation process; the invention meets the capability of assisting the coiled tubing and related downhole tools to go out of the well after the operation is finished, has stronger two-way obstacle crossing function, has good well wall adaptability, and is easy for the pipe column to reciprocate back and forth; meanwhile, the tractor adopts a self-excitation type hydraulic control design, coordinates and controls related actions, has the characteristics of high mechanical efficiency and high crawling speed, and can realize quick running-in and running-out of a pipe column; in addition, the tractor has wide application range in downhole operation, can be used for pulling out and pulling down a pipe column and can also be used for complex operation working conditions such as sand washing, drilling and grinding and the like.

Example 2:

based on embodiment 1, in this embodiment, preferably, the joint assembly includes afishing neck 2, a lockingslip 3, a sealing joint 4 and adiagonal joint 5, thefishing neck 2 is connected with the left end of the sealing joint 4 through a trapezoidal thread, and the right end of the sealing joint 4 is connected with the diagonal joint 5 through a trapezoidal thread; the external thread at the right end of theinclined joint 5 is connected with the leftouter sleeve 7, and the internal thread at the right end is connected with the leftcentral tube 18; the lockingslip 3 is embedded in thefishing neck 2 and sleeved on the coiled tubing 1, and the coiled tubing 1 penetrates through thefishing neck 2 and is connected with the sealing joint 4.

As shown in figure 1, theinclined joint 5 is funnel-shaped, inner step holes are formed in the left end and the right end of theinclined joint 5, and the diameter of the inner step hole in the left end is smaller than that of the outer step hole in the right end. The end part of the right end of theinclined joint 5 is connected with afirst compression spring 6 in the left locking mechanism.

The sealing joint 4 be the cavity cylindricality, both ends all opened outer step hole about sealing joint 4, all be equipped with trapezoidal thread on the outer step hole, sealing joint 4 is connected withscarf 5 and salvageneck 2 respectively through the outer trapezoidal thread at both ends. The left end of the sealing joint 4 is also provided with an inner step hole, and a continuous oil pipe is connected in the inner step hole.

Preferably, the left locking mechanism and the right locking mechanism are identical in structure, the left locking mechanism comprises a compression spring I6, a left outer sleeve 7, a dovetail slider retaining ring 8, a dovetail slider 9 and a wedge-shaped dovetail slider 10, the right side of the wedge-shaped dovetail slider 10 is connected with an oil discharge port sliding sleeve 13, and the left side of the wedge-shaped dovetail slider is connected with the dovetail slider retaining ring 8; one end of a first compression spring 6 is fixed on the end face of the right side of the inclined joint 5, and the other end of the first compression spring abuts against a dovetail slide block retainer ring 8; the dovetail sliding block 9 is embedded on the wedge-shaped dovetail sliding block 10 through a wedge-shaped groove at the bottom; the contact surface of the dovetail sliding block 9 and the wedge-shaped dovetail sliding block 10 is an inclined surface, and a hole matched with the dovetail sliding block 9 is formed in the left outer sleeve 7; an oil discharge port A' is arranged on the left outer sleeve 7 and is positioned at the oil discharge sliding sleeve 13; the oil inlet A is arranged on a central pipe 18 positioned at the right side of the oil discharge port sliding sleeve 13.

As shown in figure 2, wedge-shapeddovetail slide block 10 right side meets with oil dischargeopening sliding sleeve 13 among the locking mechanism, and the left side meets with dovetail slideblock retaining ring 8, and the top is contacted with the vertical inclined plane ofdovetail slide block 9 on the right-hand member portion of dovetail slideblock retaining ring 8, ensures thatdovetail slide block 9 only moves from top to bottom, can not sideslip under the locking state on the inner wall of left sideouter sleeve 7.

The oil dischargeport sliding sleeve 13 is of a hollow cylinder structure, and an inner step hole is formed in the right end of the oil dischargeport sliding sleeve 13.

As shown in fig. 3 and 6, thedovetail slide block 9 and the wedge-shapeddovetail slide block 10 are connected in a sliding manner through the tooth-shaped sliding groove and the protrusion, and the bottom of thedovetail slide block 9 is provided with a wedge-shaped groove which can be embedded into the wedge-shaped block of the wedge-shapeddovetail slide block 10 and can slide along the wedge-shaped block. 9 surfaces of forked tail slider be the tooth form groove, tooth form groove structure can provide the arm-grasping power better to improve the frictional force between the forkedtail slider 9 and the wall of a well, provide bigger traction force.

In the invention, the leftouter sleeve 7 and the wedge-shapeddovetail slide block 10 are in dynamic sealing connection and are in sealing connection by adopting two sealing rings I11.

Preferably, the telescopic reciprocating mechanism comprises a first innerpiston sliding sleeve 14, a hollow pistonpositioning baffle ring 15, ahollow piston 17 and aclamping ring 19, the first innerpiston sliding sleeve 14 is sleeved on acentral pipe 18, and the left end of the first innerpiston sliding sleeve 14 is fixedly connected with an oil dischargeport sliding sleeve 13; the hollow pistonpositioning baffle ring 15 is fixed in a groove at the left end of the inner piston sliding sleeve I14, one end of thehollow piston 17 is sleeved into the inner piston sliding sleeve I14, the other end of thehollow piston 17 is connected with the rightouter sleeve 21, and thehollow piston 17 can stretch and retract; thesnap ring 19 is fixed in a groove at the right end of the leftcentral tube 12 and limits the inner piston sliding sleeve I14.

As shown in FIG. 4, thehollow piston 17 of the present invention is a hollow cylinder structure, and has an inner step hole at the right end, and the right end of thehollow piston 17 is connected to thefirst compression spring 6 of the right locking mechanism. In the invention, the inner piston sliding sleeve I14 is connected with thehollow piston 17 in a sliding and sealing way, and is connected with thehollow piston 17 in a sealing way by adopting two sealingrings II 16. One end of thehollow piston 17 is sleeved into the innerpiston sliding sleeve 14, and the hollow piston positioning retainingring 15 limits the hollow piston. The outside of the right end of thehollow piston 17 is provided with an outer step hole, and the side surface of the outer step hole is in contact connection with the inner wall of the limitingblock 20. The left sideouter sleeve 7 and the right sideouter sleeve 21 are connected through a limitingblock 20, the outer wall of the limitingblock 20 is flush with the outer walls of the left sideouter sleeve 7 and the right sideouter sleeve 21, and the inner diameter of the limitingblock 20 is smaller than that of the left sideouter sleeve 7. The outer step hole at the right end of thehollow piston 17 is longer than the inner step hole.

The limitingblock 20 is in a hollow cylinder shape, the left end of the limiting block is provided with an outer step hole, the outer step hole is connected with the leftouter sleeve 7, and the end face of the right end of the limiting block is connected with the end face of the left end of the rightouter sleeve 21.

Preferably, the traction mechanism comprises a second innerpiston sliding sleeve 23, atraction piston 28, asecond compression spring 26, atraction sliding sleeve 27, a rightcentral tube 22 and a rightouter sleeve 21; the inner piston sliding sleeve II 23 is sleeved between the rightcentral pipe 22 and the rightouter sleeve 21, and thetraction piston 28 is sleeved between the inner piston sliding sleeve II 23 and thetraction sliding sleeve 27; a wedge-shapeddovetail slide block 9 in the right locking mechanism is connected with the left end of an inner piston slide sleeve II 23, and atraction slide sleeve 27 is connected with the right end part of a rightcentral tube 22; the oil inlet B is arranged on the rightcentral pipe 22 at the position of the inner piston sliding sleeve II 23 and is positioned at the left end of thetraction piston 28; the oil outlet B' is arranged on the rightouter sleeve 21 at thetraction sliding sleeve 27 and is positioned at the lower part of the rightouter sleeve 21; one end of thesecond compression spring 26 is contacted with the bulge of the second innerpiston sliding sleeve 23, and the other end of the second compression spring is propped against thetraction sliding sleeve 27.

As shown in FIG. 5, in the present invention, thetraction sliding sleeve 27 and thetraction piston 28 are connected in a sliding and sealing manner by two sealingrings III 24. The inner piston sliding sleeve II 23 is connected with thetraction piston 28 in a sliding and sealing way and is connected with the traction piston in a sealing way by adopting a sealing ring II 25.

Preferably, thetraction sliding sleeve 27 is a hollow cylinder structure, the right end of the traction sliding sleeve is provided with an outer step hole, the left end of the traction sliding sleeve is provided with two inner step holes, and the step side surface of the inner step hole on the left side is in sliding connection with thetraction sliding sleeve 28; the right inner step hole is fixedly connected with the right end part of the rightcentral tube 22; the diameter of the inner step hole on the left side is larger than that of the outer step hole, and the diameter of the outer step hole is larger than that of the inner step hole on the right side; thesecond compression spring 26 is supported on the step surface of the left inner step hole.

Preferably, the end part of the right end of the inner piston sliding sleeve II 23 is provided with a bulge which limits thetraction sliding sleeve 27.

The locking mechanism of the invention consists of a left locking mechanism and a right locking mechanism, wherein the right locking mechanism and the left locking mechanism have the same matching relationship. In the invention, the outer surfaces of thedovetail sliding blocks 9 in the left and right locking mechanisms adopt a tooth-shaped groove structure, and the tooth-shaped groove structure can better provide arm-grasping force so as to improve the friction force between the obstacle crossing mechanism and the well wall and provide larger traction force; the tractor can effectively adapt to the complex underground environment to achieve the obstacle crossing function, and the phenomenon that the tractor is blocked when meeting underground concave-convex soft points is avoided; meanwhile, the capacity of assisting the coiled tubing and related downhole tools to go out of the well after the operation is finished is met, and the two-way obstacle crossing function is achieved.

A use method of a hydraulic telescopic coiled tubing tractor for dense gas operation comprises the following specific steps:

when the oil inlet A works, oil is fed into the oil inlet A, the wedge-shapeddovetail sliding block 10 pushes thedovetail sliding block 9 to be in contact with a well wall and locked, meanwhile, thehollow piston 17 extends out to reach an extension state, the inner piston sliding sleeve II 23 is pushed to open the oil inlet B, and theclamp ring 19 limits the extending position of thehollow piston 17; the oil inlet A and the oil inlet B simultaneously feed oil, when thehollow piston 17 extends to the limit position, the oil discharge port A' is opened, and the wedge-shapeddovetail slide block 10 is retracted under the action of thecompression spring 6; the oil inlet B is fed to enable the right locking mechanism to be locked, meanwhile, thetraction piston 28 is pushed to move right to reach the extreme position, and then the rightcentral tube 22 is pulled to complete traction; after the tractor reaches the extreme position, the oil discharge port B' discharges oil, the right locking mechanism retracts, and the hydraulic telescopic coiled tubing tractor returns to the initial state.

All parts are machined, burrs and sharp edges are removed, and the parts are assembled after being cleaned; all parts are free from blocking during assembly; after the assembly is completed, all functions are tested, the maximum opened peripheral diameter of the lockingslip 3 is measured, and the stroke and the pressure are recorded. The left and right locking mechanisms can realize double locking, so that the traction force is increased. The obstacle crossing capability can be improved by the cooperation of the left locking mechanism and the right locking mechanism.

The above examples are merely illustrative and not intended to limit the scope of the present invention, and any design similar or equivalent to the present invention is within the scope of the present invention, and the structure and method steps of the apparatus not described in detail in the present invention are prior art and will not be further described in the present invention.

Claims (8)

1. The utility model provides a telescopic coiled tubing tractor of hydraulic pressure for dense gas operation which characterized in that: the oil pipe joint comprises at least an outer sleeve, a coiled oil pipe (1), a joint component, a locking mechanism, an oil discharge sliding sleeve (13), a central pipe (18), a telescopic reciprocating mechanism and a traction mechanism, wherein the number of the locking mechanisms is two, the locking mechanisms comprise a left locking mechanism and a right locking mechanism, the central pipe (18) is positioned in the outer sleeve, the joint component, the left locking mechanism, the oil discharge sliding sleeve (13), the telescopic reciprocating mechanism, the right locking mechanism and the traction mechanism are sequentially connected and sleeved on the central pipe (18), the central pipe (18) comprises a left central pipe (12) and a right central pipe (22), an oil inlet A is formed in the left central pipe (12), and an oil inlet B is formed in the right central pipe (22); the coiled tubing (1) is communicated with a central tube (18) through a joint component; the outer sleeve comprises a left outer sleeve (7) and a right outer sleeve (21), the left outer sleeve (7) is provided with an oil discharge port A ', and the right outer sleeve (21) is provided with an oil discharge port B'.

2. The hydraulic telescopic coiled tubing tractor for dense gas operation as claimed in claim 1, wherein: the connector assembly comprises a fishing neck (2), a locking slip (3), a sealing connector (4) and an inclined connector (5), wherein the fishing neck (2) is connected with the left end of the sealing connector (4) through a trapezoidal thread, and the right end of the sealing connector (4) is connected with the inclined connector (5) through a trapezoidal thread; the right end external thread of the inclined joint (5) is connected with the left outer sleeve (7), and the right end internal thread is connected with the left central tube (18); the locking slip (3) is embedded in the fishing neck (2) and sleeved on the coiled tubing (1), and the coiled tubing (1) penetrates through the fishing neck (2) and is connected with the sealing joint (4).

3. The hydraulic telescopic coiled tubing tractor for dense gas operation as claimed in claim 1, wherein: the left locking mechanism and the right locking mechanism are identical in structure, the left locking mechanism comprises a compression spring I (6), a left outer sleeve (7), a dovetail slider retaining ring (8), a dovetail slider (9) and a wedge-shaped dovetail slider (10), the right side of the wedge-shaped dovetail slider (10) is connected with an oil discharge port sliding sleeve (13), and the left side of the wedge-shaped dovetail slider (10) is connected with the dovetail slider retaining ring (8); one end of the compression spring I (6) is fixed on the right end face of the inclined joint (5), and the other end of the compression spring I props against the dovetail slide block retainer ring (8); the dovetail sliding block (9) is embedded on the wedge-shaped dovetail sliding block (10) through a wedge-shaped groove at the bottom; the contact surface of the dovetail sliding block (9) and the wedge-shaped dovetail sliding block (10) is an inclined surface, and a hole matched with the dovetail sliding block (9) is formed in the left outer sleeve (7); an oil discharge port A' is arranged on the left outer sleeve (7) and is positioned at the oil discharge port sliding sleeve (13); the oil inlet A is arranged on a central pipe (18) positioned at the right side of the oil discharge port sliding sleeve (13).

4. The hydraulic telescopic coiled tubing tractor for dense gas operation as claimed in claim 1, wherein: the telescopic reciprocating mechanism comprises a first inner piston sliding sleeve (14), a hollow piston positioning baffle ring (15), a hollow piston (17) and a clamping ring (19), wherein the first inner piston sliding sleeve (14) is sleeved on a central pipe (18), and the left end of the first inner piston sliding sleeve (14) is fixedly connected with an oil discharge port sliding sleeve (13); a hollow piston positioning baffle ring (15) is fixed in a groove at the left end of the inner piston sliding sleeve I (14), one end of a hollow piston (17) is sleeved into the inner piston sliding sleeve I (14), the other end of the hollow piston (17) is connected with a right outer sleeve (21), and the hollow piston (17) can stretch out and draw back; the snap ring (19) is fixed in a groove at the right end of the left central tube (12) and limits the inner piston sliding sleeve I (14).

5. The hydraulic telescopic coiled tubing tractor for dense gas operation as claimed in claim 1, wherein: the traction mechanism comprises a second inner piston sliding sleeve (23), a traction piston (28), a second compression spring (26), a traction sliding sleeve (27), a right central tube (22) and a right outer sleeve (21); the inner piston sliding sleeve II (23) is sleeved between the right central pipe (22) and the right outer sleeve (21), and the traction piston (28) is sleeved between the inner piston sliding sleeve II (23) and the traction sliding sleeve (27); a wedge-shaped dovetail slide block (10) in the right locking mechanism is connected with the left end of an inner piston sliding sleeve II (23), and a traction sliding sleeve (27) is connected with the right end of a right central tube (22); the oil inlet B is arranged on the right central pipe (22) at the position of the inner piston sliding sleeve II (23) and is positioned at the left end of the traction piston (28); the oil outlet B' is arranged on the right outer sleeve (21) at the traction sliding sleeve (27) and is positioned at the lower part of the right outer sleeve (21); one end of the second compression spring (26) is in contact with the bulge of the second inner piston sliding sleeve (23), and the other end of the second compression spring abuts against the traction sliding sleeve (27).

6. The hydraulic telescopic coiled tubing tractor for dense gas operation as claimed in claim 5, wherein: the traction sliding sleeve (27) is of a hollow cylinder structure, the right end of the traction sliding sleeve is provided with an outer step hole, the left end of the traction sliding sleeve is provided with two inner step holes, and the step side surface of the inner step hole on the left side is connected with the traction sliding sleeve (28) in a sliding manner; the right inner step hole is fixedly connected with the right end part of the right central tube (22); the diameter of the inner step hole on the left side is larger than that of the outer step hole, and the diameter of the outer step hole is larger than that of the inner step hole on the right side; and the second compression spring (26) is supported on the step surface of the left inner step hole.

7. The hydraulic telescopic coiled tubing tractor for dense gas operation as claimed in claim 5, wherein: and the end part of the right end of the inner piston sliding sleeve II (23) is provided with a bulge which limits the traction sliding sleeve (27).

8. The use method of the hydraulic telescopic coiled tubing tractor for the dense gas operation is characterized by comprising the following steps of: the method comprises the following specific steps:

when the oil inlet A works, oil is fed into the oil inlet A, the wedge-shaped dovetail sliding block (10) pushes the dovetail sliding block (9) to be in contact with a well wall and locked, meanwhile, the hollow piston (17) extends out to reach an extension state, the inner piston sliding sleeve II (23) is pushed to open the oil inlet B, and the extension position of the hollow piston (17) is limited by the clamping ring (19); the oil inlet A and the oil inlet B are simultaneously fed, when the hollow piston (17) extends to a limit position, the oil discharging port A' is opened, and the wedge-shaped dovetail slide block (10) is retracted under the action of the compression spring 6; the right locking mechanism is locked by feeding oil into the oil inlet B, the traction piston (28) is pushed to move right to reach the extreme position, and then the right central tube (22) is pulled to complete traction; after the tractor reaches the extreme position, the oil discharge port B' discharges oil, the right locking mechanism retracts, and the hydraulic telescopic coiled tubing tractor returns to the initial state.

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