Retrievable fishing device and method of fishing

Abstract

The application discloses a retrievable fishing device and a fishing method thereof, and relates to the technical field of oil drilling. The retrievable fishing device comprises a fishing barrel, an upper joint is arranged on the fishing barrel, and the fishing device further comprises a drill bit fixed to the lower end of the fishing barrel, and an inner support sleeve sleeved in the fishing barrel and axially slidably connected with the inner wall of the fishing barrel. At least two conical petals are circumferentially distributed on the lower end of the inner support sleeve, and the plurality of conical petals are enclosed to form a frustum structure. A guide hole is drilled by the drill bit in advance, the operation mode of directly biting the inner wall of the fish by the traditional public cone or the split public cone is changed, the guide hole is used for providing accurate axial guidance and circumferential positioning for the introduction of the conical petal combination, and the accuracy and consistency of the thread cutting position of the made-up thread are ensured, so that the initial success rate of the fishing operation and the made-up quality are significantly improved. In addition, the short frustum structure enclosed by the conical petals is matched with the drill bit, the made-up depth is reduced, and the retrievable fishing device is applicable to some fish with thin wall thickness.

Description

Technical Field

[0001] This invention relates to the field of oil drilling technology, specifically to a retractable fishing device and its fishing method. Background Technology

[0002] The male taper is currently the most commonly used internal hole snapping and retrieval tool in drilling or well workover projects. It can achieve snapping and retrieval by simply applying pressure and rotating. Its advantages are simple structure, easy operation, wide retrieval range, and compatibility with both positive and negative taper drill pipes. It can adapt to complex retrieval under different conditions. As long as the fallen fish has an internal hole (cavity) and a certain strength, it can be retrieved. It is the most effective and economical retrieval tool and method for retrieving fallen fish.

[0003] Chinese invention patent application CN109083610B discloses a retractable retrieval male cone. The retrieval male cone has a retractable function, which prevents accidents caused by retrieval failure from making the downhole environment more complex. In addition, the male cone adopts a three-lobed male cone body, and the gap formed between each pair of lobes is convenient for cutting and clipping.

[0004] However, due to the large length, high hardness, and strong brittleness of the male cone, it is prone to breakage. In addition, the large length of the male cone often requires it to penetrate deep into the fish's internal cavity when making a hook, which makes it less suitable for some equipment with thin walls. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a retractable salvage device and salvage method, solving the problems raised in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a retractable retrieval device, comprising a retrieval cylinder with an upper connector, and further comprising: a drill bit fixed to the lower end of the retrieval cylinder; an inner support sleeve fitted inside the retrieval cylinder and axially slidably connected to the inner wall of the retrieval cylinder, wherein at least two conical lobes are circumferentially distributed at the lower end of the inner support sleeve, the multiple conical lobes forming a frustum structure, and the inner diameter of the opening formed at the lower end of the frustum structure is adapted to the maximum outer diameter of the drill bit; a gap is provided between two adjacent conical lobes, and an inner support cylinder is axially slidably connected inside the inner support sleeve, the inner support cylinder moving downward to radially open the gap, thereby enhancing the connection strength between the conical lobes and the inner wall of the fish.

[0007] Furthermore, the retrieval cylinder has an internal cavity, and the upper end of the inner support sleeve is fixed with a first piston that is slidably connected to the cavity. The closed space between the first piston and the top of the cavity forms a first hydraulic chamber. A connecting pipe is fixed in the middle of the retrieval cylinder, the lower end of the connecting pipe is fixedly connected to the upper end of the drill bit, and the side wall of the connecting pipe is provided with a first oil guide hole that communicates with the top area inside the first hydraulic chamber.

[0008] Furthermore, the sealing space between the top of the inner support cylinder and the first piston constitutes the second hydraulic chamber; the inside of the retrieval cylinder is provided with a lifting chamber above the cavity, and a lifting pipe is provided inside the lifting chamber. The upper end of the lifting pipe is fixed with the second piston, and the lower end of the lifting pipe extends into the second hydraulic chamber. A second oil guide hole is provided on the outer side of the lifting pipe near the upper end, which is used to connect the first hydraulic chamber and the second hydraulic chamber when the fish is retrieved.

[0009] Furthermore, when the lifting pipe descends to its lowest point of travel, the height of the second oil guide hole is lower than the height of the first oil guide hole.

[0010] Furthermore, the outer surface of the cone is provided with a threaded joint, and the lower end of the cone is provided with a cutting head.

[0011] Furthermore, a balance hole is provided on the wall of the retrieval cylinder, which connects the lower part of the cavity to the outside of the retrieval cylinder.

[0012] Furthermore, a limiting ring is fixed at the lower end of the inner support sleeve; a third piston is provided at the upper end of the inner support cylinder and is slidably connected to the inner wall of the inner support sleeve, and a reset spring is provided on the outer side of the inner support cylinder between the third piston and the limiting ring.

[0013] Furthermore, the lower outer end of the inner support cylinder is provided with an inclined surface whose outer diameter gradually decreases from top to bottom, and the inclined surface abuts against the inner wall of the cone-shaped petal;

[0014] The inner support cylinder descends, and the inclined surface radially expands the conical petals to increase the cross-sectional area of ​​the frustum structure formed by the enclosing conical petals.

[0015] In addition, the present invention also provides a retrieval method for a retractable retrieval device, applicable to the aforementioned retractable retrieval device, comprising the following steps:

[0016] Step 1, Drilling Preparation: Connect the retrieval device to the lower end of the drill string, lower it to the top of the fish that fell into the well, and pump in flushing fluid to clean the fish's head;

[0017] Step 2, Drilling operation: Continue to lower the drill string so that the drill bit drills a guide hole at the center of the top surface of the fish;

[0018] Step 3, Clip Creation and Retrieval: Pump hydraulic medium into the drill string to drive the inner support sleeve and cone to descend, while rotating the drill string to mechanically create clips on the inner wall of the guide hole.

[0019] Step 4, Locking and Strengthening: Continuous pump pressure pushes the inner support cylinder downward to radially open the cone flap, making its engagement with the inner wall of the fish sinker more tight;

[0020] Step 5, Lifting and Judgment: Lift the drill string. If the fish moves with it, continue lifting to retrieve the fish.

[0021] Furthermore, if the fish gets stuck and cannot be pulled out during the lifting process in step five, the pump pressure inside the drill string is reduced, and the drill string is rotated in the opposite direction. At this time, the inner support cylinder moves upward, causing the inner support cylinder to separate from the cone. After the cone loses its radial support, it is pulled out of the fish thread under the action of rotation, thereby realizing the separation of the retrieval device from the fish and safely retrieving the retrieval device.

[0022] The present invention has the following beneficial effects:

[0023] (1) The retractable retrieval device and its retrieval method, by pre-drilling a guide hole with a drill bit, changes the traditional operation method of directly biting the inner wall of the fallen fish with a male cone or a split male cone. The guide hole provides precise axial guidance and circumferential positioning for the introduction of the cone-shaped assembly, ensuring the accuracy and consistency of the thread cutting position, thereby significantly improving the initial success rate and thread quality of the retrieval operation. In addition, the short cone structure formed by the cone-shaped assembly cooperates with the drill bit to reduce the thread depth, which is also applicable to some fallen fish with thin walls.

[0024] (2) The retractable fishing device and its fishing method replace the traditional one-piece long cone male cone with a short cone structure formed by multiple circumferentially distributed cone petals. This significantly shortens the axial length of the working section, reduces the risk of tool jamming in curved well sections or complex well holes, and improves tool passability. At the same time, it abandons the traditional slender guide tip at the front end of the male cone, so that the cone petals have a thicker cross section and a larger material bearing area from the root of the structure, which greatly enhances the overall compressive, torsional and tensile strength, and can withstand higher fishing and lifting loads and more severe torque fluctuations, thus improving the structural reliability and durability of the tool under heavy-load fishing conditions.

[0025] (3) When the retractable retrieval device and its retrieval method need to be withdrawn, only the pump pressure inside the drill string needs to be reduced. The preload of the reset spring can push the inner support cylinder upward, so that its inclined surface separates from the inner wall of the cone. The cone shrinks radially under its own elasticity, and the meshing force with the inner wall thread of the fallen fish is rapidly reduced. At this time, the drill string is rotated in the opposite direction, so that the cone thread can be smoothly screwed out. The entire withdrawal process does not depend on external equipment and has high reliability.

[0026] (4) The retractable fishing device and its fishing method drive the inner support sleeve and the cone to complete the downward buckling action by setting the first hydraulic chamber and the first piston. By setting the lifting pipe, the second piston, the second oil guide hole and the second hydraulic chamber, the oil circuit is automatically connected at the end of the first piston stroke, driving the inner support cylinder downward. The inclined surface at the lower end of the inner support cylinder opens the cone to achieve radial locking, which greatly enhances the meshing strength and connection reliability of the cone buckling thread and the inner wall of the fish. The entire hydraulic action sequence is guaranteed by the mechanical structure such as the relative height position of the first oil guide hole and the second oil guide hole. No complex external commands are required. The drilling-buckle-locking process can be completed automatically and reliably by the continuous and changing surface pump pressure. The operation is simple and the status judgment is intuitive (by the change of pump pressure), which greatly improves the controllability and success rate of downhole operations.

[0027] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the retractable salvage device during salvage operations.

[0029] Figure 2 This is a schematic diagram of a retractable salvage device.

[0030] Figure 3 This is a schematic diagram of the internal structure of a retractable salvage device.

[0031] Figure 4 For retractable salvage devices Figure 3 The main view;

[0032] Figure 5 This is a schematic diagram of the retractable salvage device when the first piston is at the highest point of the cavity.

[0033] Figure 6 This is a schematic diagram of the retractable salvage device when the first piston is located at the lowest point of the cavity.

[0034] Figure 7 This is a schematic diagram of the internal support cylinder in the retractable salvage device when it is descending.

[0035] Figure 8 For retractable salvage devices Figure 7 The main view;

[0036] Figure 9 This is a schematic diagram of the conical flap structure in a retractable retrieval device;

[0037] Figure 10 For retractable salvage devices Figure 9 A bottom view;

[0038] Figure 11This is a schematic diagram of the inner support cylinder in a retractable salvage device.

[0039] In the diagram, 1. retrieval tube; 2. upper connector; 3. balance hole; 4. cone; 5. drill bit; 6. connecting pipe; 7. first oil guide hole; 8. first piston; 9. first hydraulic chamber; 10. inner support sleeve; 11. lifting chamber; 12. lifting pipe; 13. second piston; 14. second oil guide hole; 15. cutter head; 16. inner support sleeve; 17. second hydraulic chamber; 18. return spring; 19. limit ring; 20. gap; 21. inclined plane. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "around", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0042] The following is based on Figures 1-11 This invention describes a retractable salvage device and salvage method provided in an embodiment of the present invention.

[0043] Please refer to Figures 1-11 This invention provides a technical solution: a retractable retrieval device, including a retrieval cylinder 1, an upper connector 2 on the retrieval cylinder 1, and a pin at the lower end of the retrieval cylinder 1. The pin can play a guiding and straightening role during the well running process, avoiding tool deflection and affecting retrieval accuracy. The upper connector 2 is preferably fixed to the external drill string by a threaded connection to ensure reliable connection and no detachment under high pressure and high torque drilling environment. It also includes a drill bit 5, which is fixed to the lower end of the retrieval cylinder 1 and is used to drill a guide hole at the center of the top surface of the fallen fish.

[0044] In addition, the retractable retrieval device provided by the present invention also includes an inner support sleeve 10, which is fitted inside the retrieval cylinder 1 and is axially slidably connected to the inner wall of the retrieval cylinder 1. At least two conical lobes 4 are circumferentially distributed at the lower end of the inner support sleeve 10, preferably three conical lobes 4. The multiple conical lobes 4 enclose each other to form a frustum structure, which can be used as a male cone. The inner diameter of the opening formed at the lower end of the frustum structure is adapted to the maximum outer diameter of the drill bit 5. When the conical lobes 4 are not in use, they retract into the retrieval cylinder 1, thereby providing effective protection for the conical lobes 4 and preventing damage to their surface. Regarding the thread damage during thread making, it should be noted that a guide hole is first drilled at the center of the top surface of the fish using drill bit 5. Then, the frustum structure composed of cone petals 4 is spun and introduced into the guide hole. The guide hole facilitates the subsequent thread making of cone petals 4, improves the traction effect, ensures the stability of thread making, and reduces the difficulty of thread making of cone petals 4. On the other hand, it is beneficial to improve the traditional conical male cone into the frustum-shaped male cone in this embodiment, thereby shortening the length of the male cone. This can avoid the excessive thread making depth caused by an excessively long male cone, and can also directly eliminate the thinner part at the front end of the traditional male cone, thereby improving the strength of the male cone.

[0045] To understand it in more detail, the truncated cone structure formed by the combination of cone 4 has a shorter axial length, reducing the risk of deviation or jamming in curved wellbores or complex fishing postures, and improving tool passability. Secondly, it abandons the slender tip used for guidance at the front end of the traditional male cone, so that cone 4 has sufficient cross-sectional area and material thickness from the root, thereby greatly improving the overall structural strength and torsional resistance, and can withstand higher threading torque and lifting load. The cooperation between the guide hole and cone 4 makes the threading process occur within the prefabricated hole wall, which makes the threading thread on cone 4 cut more smoothly and the force more even, effectively avoiding problems such as slippage, biting or incomplete threading caused by unclear initial contact points in traditional methods.

[0046] In cases where the fish cannot be retrieved, to facilitate separation of the retrieval device provided in this embodiment from the fish, a gap 20 is provided between two adjacent cone-shaped segments 4. An inner support cylinder 16 is axially slidably connected inside the inner support sleeve 10. The inner support cylinder 16 moves downward to radially open the gap 20, thereby enhancing the connection strength between the cone-shaped segments 4 and the inner wall of the fish. This forces each cone-shaped segment 4 to overcome its own elasticity and expand radially outward, thus tightly adhering to the thread of the guide hole. It can even perform secondary reinforcement engagement on the already manufactured thread, greatly enhancing the connection strength and tensile strength. When the inner support cylinder 16 moves upward, the cone-shaped segments 4 contract inward under the action of their own material elastic recovery force, reducing their radial dimension and making the engagement with the thread of the fish hole wall loose. At this time, applying a reverse torque can make the threaded part on the cone-shaped segment 4 relatively easy to unscrew, achieving reliable separation from the fish.

[0047] like Figures 3-8As shown, in order to realize the movement of the inner support sleeve 10, the retractable retrieval device provided in this embodiment has a cavity inside the retrieval cylinder 1. The upper end of the inner support sleeve 10 is fixed with a first piston 8 that is axially slidably connected to the cavity. The closed space between the first piston 8 and the top of the cavity forms a first hydraulic chamber 9. A connecting pipe 6 is fixed in the middle of the retrieval cylinder 1. The lower end of the connecting pipe 6 is fixedly connected to the upper end of the drill bit 5. The side wall of the connecting pipe 6 is provided with a first oil guide hole 7 that communicates with the top area inside the first hydraulic chamber 9. The area of ​​the connecting pipe 6 below the first oil guide hole 7 is a solid structure to improve the strength of the drill bit 5. In addition, it should be noted that when the first piston 8 is at the top of the cavity, the lower end of the inner support sleeve 10 is located below the bottom of the cavity to achieve relative sealing of the cavity and prevent impurities from entering the cavity.

[0048] Specifically, during the buckle-making process, hydraulic medium is pumped into the first hydraulic chamber 9 through the connecting pipe 6 and the first oil guide hole 7 to push the first piston 8 downward, causing the inner support sleeve 10 to drive the cone 4 downward. At this time, the retrieval cylinder 1 is rotated to press the cone 4 into the guide hole to form threads.

[0049] like Figures 3-8 As shown, in order to realize the movement of the inner support cylinder 16, the retractable retrieval device provided in this embodiment forms a second hydraulic chamber 17 in the sealed space between the top of the inner support cylinder 16 and the first piston 8. By pumping hydraulic medium into the second hydraulic chamber 17 and controlling the internal pressure of the second hydraulic chamber 17, the lifting and lowering of the inner support cylinder 16 can be controlled.

[0050] To facilitate the delivery of hydraulic medium, the retrieval cylinder 1 provided in this embodiment has a lifting chamber 11 located above the cavity. The lifting chamber 11 has a lifting pipe 12 inside, and a second piston 13 is fixed at the upper end of the lifting pipe 12. The lower end of the lifting pipe 12 extends into the second hydraulic chamber 17. A second oil guide hole 14 is provided on the outer side of the lifting pipe 12 near the upper end. This hole connects the first hydraulic chamber 9 and the second hydraulic chamber 17 when the fish is retrieved. When the second piston 13 moves to the lowest point of its stroke, there is a negative pressure above the second piston 13, which helps to assist the first piston 8 in resetting during later storage. At this time, the second oil guide hole 14 connects the first hydraulic chamber 9 and the second hydraulic chamber 17, so that the hydraulic medium inside the second hydraulic chamber 17 can flow into the second hydraulic chamber 17 through the second oil guide hole 14 and the lifting pipe 12, thereby achieving a hydraulic transmission effect to push the inner support cylinder 16 downward until the lower end of the inner support cylinder 16 abuts against the cone 4. At this time, the pump pressure increases instantaneously to facilitate the determination of whether the cone 4 has fully extended.

[0051] like Figures 6-8As shown, when the lifting pipe 12 provided in this embodiment descends to its lowest point of travel, the height of the second oil guide hole 14 is lower than that of the first oil guide hole 7. This ensures that the second oil guide hole 14 will only descend to a position sufficient to communicate with the first hydraulic chamber 9 after the first piston 8 drives the inner support sleeve 10 to complete its entire downward stroke (i.e., the cone 4 completes the buckling and reaches the predetermined position). This avoids operational disorder caused by misoperation or pressure fluctuations, ensures the strict execution of the salvage process steps, and improves the success rate and predictability of the operation.

[0052] like Figure 9 and Figure 10 As shown, in order to facilitate the entry of the cone 4 into the guide hole, the outer surface of the cone 4 provided in this embodiment is provided with a threaded thread, and the lower end of the cone 4 is provided with a cutting head 15 for cutting.

[0053] The cutter head 15 itself is also frustoconical, and its taper is greater than that of the upper cone 4. When the cutter head 15 enters the guide hole, it mainly serves to guide and slightly adjust or partially enlarge the guide hole, clearing obstacles for the subsequent cone 4 to enter smoothly. The larger taper means that the radial pressure of the cutter head 15 against the hole wall increases more slowly, focusing on cutting rather than strong extrusion. The taper of the thread-forming part of the cone 4 is smaller. When it follows, the contact area with the hole wall is larger, and the pressure per unit area is greater. This allows for more effective cold extrusion thread forming, effectively preventing the failure situation where there is not enough metal material for extrusion of the subsequent thread forming due to excessive hole enlargement at the front end, thus ensuring the quality of thread forming.

[0054] like Figures 1-8 As shown, to facilitate the reset of the first piston 8 after the retractable salvage device provided in this embodiment is completed, a balance hole 3 is provided on the wall of the salvage cylinder 1. The balance hole 3 connects the lower part of the cavity to the outside of the salvage cylinder 1. The setting of the balance hole 3 is conducive to the upward movement of the first piston 8. In addition, it should be noted that when the first piston 8 descends to the bottom to perform the snapping operation, the balance hole 3 is blocked by the first piston 8, ensuring the sealing of the first hydraulic chamber 9, thereby establishing an effective hydraulic thrust. When the internal reset of the tool is required (such as after withdrawal and retraction), the cone 4 is pushed to separate the first piston 8 from the balance hole 3, so that the balance hole 3 is in the open state. The space below the first piston 8 can be balanced with the external environmental pressure through the balance hole 3, avoiding the obstruction of the upward movement of the first piston 8 due to the formation of vacuum or high pressure, ensuring that the inner support sleeve 10 and the cone 4 can be smoothly retracted to the initial position, preparing for the next salvage operation or drilling.

[0055] like Figures 5-8As shown, in order to facilitate the upward movement of the inner support cylinder 16 and separate the inclined surface 21 from the cone 4, the lower end of the inner support sleeve 10 provided in this embodiment is fixed with a limiting ring 19, the upper end of the inner support cylinder 16 is provided with a third piston that is slidably connected to the inner wall of the inner support sleeve 10, and a return spring 18 is provided on the outer side of the inner support cylinder 16 between the third piston and the limiting ring 19.

[0056] In practical use, if the fish gets stuck and cannot be pulled out, the pump pressure inside the drill string is reduced so that the pump pressure intensity is less than the rebound force of the return spring 18. At this time, under the elastic force of the return spring 18, the inner support cylinder 16 is pushed upward, which further causes the hydraulic medium inside the second hydraulic chamber 17 to flow back to the first hydraulic chamber 9 through the lifting pipe 12 and the second oil guide hole 14.

[0057] like Figure 11 As shown, in order to improve the locking effect of the inner support cylinder 16 on the cone 4, the lower outer side of the inner support cylinder 16 provided in this embodiment is provided with an inclined surface 21 whose outer diameter gradually decreases from top to bottom. The inclined surface 21 abuts against the inner wall of the cone 4, increasing the contact area between the inner support cylinder 16 and the cone 4, thereby improving the locking effect of the inner support cylinder 16 on the cone 4. In specific use, as the inner support cylinder 16 moves downward, the inclined surface 21 radially expands the cone 4 to increase the cross-sectional area of ​​the frustum structure formed by the cone 4.

[0058] During use (operation), the retrieval device is lowered to the top of the fish in the well. A guide hole is drilled at the center of the top surface of the fish using drill bit 5. Hydraulic medium is pumped into the connecting pipe 6. The hydraulic medium flows into the first hydraulic chamber 9 through the first oil guide hole 7, thereby pushing the first piston 8 downward. This causes the inner support sleeve 10 to drive the cone 4 downward. At the same time, the retrieval cylinder 1 rotates, causing the cutter head 15 to act on the guide hole to continue expanding the hole. The threaded joint of the cone 4 presses against the inner wall of the guide hole, achieving mechanical threading. At this time, the pump pressure increases, and the first piston 8, through the riser pipe 12, causes... The second piston 13 moves downward, continuously pumping hydraulic medium until the second oil guide hole 14 is exposed inside the lifting chamber 11. At this time, the hydraulic medium flows into the second oil pressure chamber 17 through the lifting chamber 11 and the lifting pipe 12. At this time, the pump pressure drops instantly until the lower end inclined surface 21 of the inner support cylinder 16 abuts against the inner wall of the cone 4. At this time, the pump pressure increases rapidly. When the pressure is stabilized, the cone 4 completely enters the fish. At this time, the second oil guide hole 14 is located below the first oil guide hole 7, the return spring 18 contracts and the balance hole 3 is blocked by the first piston 8.

[0059] If the fish moves when the drill string is lifted, continue lifting to retrieve it. If the fish gets stuck and cannot be retrieved, reduce the pump pressure inside the drill string so that the pump pressure is less than the return force of the return spring 18. At this time, under the action of the return spring 18, the inner support cylinder 16 is pushed upward, further causing the hydraulic medium inside the second hydraulic chamber 17 to flow back to the first hydraulic chamber 9 through the lifting pipe 12 and the second oil guide hole 14, and enter the connecting pipe 6 through the first oil guide hole 7. At this time, the inclined surface 21 separates from the cone 4. After losing radial support, the cone 4 is pulled out of the fish thread under the action of rotation, thereby realizing the separation of the retrieval device from the fish and safely retrieving the retrieval device. The entire withdrawal process does not rely on external equipment and has high reliability.

[0060] In addition, the present invention also provides a salvage method for a retractable salvage device, applicable to retractable salvage devices, comprising the following steps:

[0061] Step 1, Drilling preparation: Connect the retrieval device to the lower end of the drill string, lower it to the top of the fish that fell into the well, and pump in flushing fluid to clean the head of the fish.

[0062] Step 2, Drilling operation: Continue to lower the drill string so that drill bit 5 drills a guide hole at the center of the top surface of the fish;

[0063] Step 3, threading and retrieval: Pump hydraulic medium into the drill string to increase the pressure in the first hydraulic chamber 9, drive the first piston 8 to move the inner support sleeve 10 and the cone 4 downward, and at the same time rotate the drill string so that the threading thread of the cone 4 mechanically threads on the inner wall of the guide hole.

[0064] Step 4, Locking Enhancement: Continuous pump pressure allows hydraulic medium to enter the second oil pressure chamber 17, pushing the inner support cylinder 16 downward. Its inclined surface 21 radially expands the cone 4, making the cone 4 more tightly engaged with the inner wall of the fish.

[0065] Step 5, Lifting and Judgment: Lift the drill string. If the fish moves with it, continue lifting to retrieve the fish.

[0066] If the fish gets stuck and cannot be pulled out during the lifting process in step five, the pump pressure inside the drill string is reduced, causing the pressure in the first hydraulic chamber 9 to drop, and the drill string is rotated in the opposite direction. At this time, the hydraulic medium in the second hydraulic chamber 17, with the assistance of the return spring 18, flows back through the lifting pipe 12 and the second guide oil hole 14, pushing the inner support cylinder 16 upward, causing its inclined surface 21 to separate from the cone 4. After losing radial support, the cone 4 is pulled out of the fish thread under the action of rotation, thereby realizing the separation of the retrieval device from the fish and safely retrieving the retrieval device.

[0067] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0068] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A retractable retrieval device, comprising a retrieval cylinder (1) having an upper connector (2) thereon, characterized in that, Also includes: The drill bit (5) is fixed to the lower end of the retrieval tube (1); The inner support sleeve (10) is fitted inside the retrieval tube (1) and is axially slidably connected to the inner wall of the retrieval tube (1). At least two cone lobes (4) are distributed circumferentially at the lower end of the inner support sleeve (10). Multiple cone lobes (4) are enclosed to form a frustum structure, and the inner diameter of the opening formed at the lower end of the frustum structure is adapted to the maximum outer diameter of the drill bit (5). A gap (20) is provided between two adjacent cones (4). An inner support cylinder (16) is slidably connected in the inner support sleeve (10) along the axial direction. The inner support cylinder (16) moves downward to radially open the gap (20) to enhance the connection strength between the cone (4) and the inner wall of the fish. The retrieval cylinder (1) has a cavity inside, and the upper end of the inner support sleeve (10) is fixed with a first piston (8) that is slidably connected to the cavity. The closed space between the first piston (8) and the top of the cavity forms a first hydraulic chamber (9). The middle part of the retrieval tube (1) is fixed with a connecting pipe (6), the lower end of the connecting pipe (6) is fixedly connected to the upper end of the drill bit (5), and the side wall of the connecting pipe (6) is provided with a first oil guide hole (7) that communicates with the top area inside the first oil pressure chamber (9). The sealing space between the top of the inner support cylinder (16) and the first piston (8) forms the second hydraulic chamber (17). The retrieval tube (1) has a lifting chamber (11) located above the cavity inside. The lifting chamber (11) has a lifting pipe (12) inside. The upper end of the lifting pipe (12) is fixed with a second piston (13), and the lower end of the lifting pipe (12) extends into the second hydraulic chamber (17). The outer side of the lifting pipe (12) is provided with a second oil guide hole (14) near the upper end, which is used to connect the first hydraulic chamber (9) and the second hydraulic chamber (17) when the fish is retrieved. When the lifting pipe (12) descends to its lowest point of travel, the height of the second oil guide hole (14) is lower than that of the first oil guide hole (7). The outer surface of the cone (4) is provided with a threaded thread, and the lower end of the cone (4) is provided with a cutting head (15). The lower end of the inner support sleeve (10) is fixed with a limit ring (19). The upper end of the inner support cylinder (16) is provided with a third piston that is slidably connected to the inner wall of the inner support sleeve (10), and a return spring (18) is provided on the outer side of the inner support cylinder (16) between the third piston and the limiting ring (19).

2. The retractable salvage device according to claim 1, characterized in that, The salvage cylinder (1) has a balance hole (3) on its wall, which connects the lower part of the cavity to the outside of the salvage cylinder (1).

3. The retractable salvage device according to claim 2, characterized in that, The lower outer side of the inner support cylinder (16) is provided with an inclined surface (21) whose outer diameter gradually decreases from top to bottom, and the inclined surface (21) abuts against the inner wall of the cone (4); The inner support cylinder (16) moves downward, and the inclined surface (21) radially expands the cone petals (4) to increase the cross-sectional area of ​​the frustum structure formed by the cone petals (4).

4. A salvage method using a retractable salvage device, characterized in that, An applicable retractable retrieval device according to any one of claims 1-3 includes the following steps: Step 1, Drilling Preparation: Connect the retrieval device to the lower end of the drill string, lower it to the top of the fish that fell into the well, and pump in flushing fluid to clean the fish's head; Step 2, Drilling operation: Continue to lower the drill string so that the drill bit (5) drills a guide hole at the center of the top surface of the fish; Step 3, snapping and retrieval: Pump hydraulic medium into the drill string to drive the inner support sleeve (10) and the cone (4) downward, while rotating the drill string to make the cone (4) mechanically snap on the inner wall of the guide hole; Step 4, Locking and Strengthening: Continuous pump pressure pushes the inner support cylinder (16) downward to radially open the cone (4), making it more tightly engaged with the inner wall of the fish; Step 5, Lifting and Judgment: Lift the drill string. If the fish moves with it, continue lifting to retrieve the fish.

5. The salvage method of the retractable salvage device according to claim 4, characterized in that, If the fish gets stuck and cannot be pulled out during the lifting process in step five, reduce the pump pressure inside the drill string and rotate the drill string in the opposite direction. At this time, the inner support cylinder (16) moves upward, causing the inner support cylinder (16) to separate from the cone (4). After the cone (4) loses its radial support, it exits from the fish-falling thread under the action of rotation, thereby realizing the separation of the retrieval device from the fish and safely retrieving the retrieval device.

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