Returnable salvage device and method capable of being pressed repeatedly

Abstract

The invention relates to the technical field of underground salvage, in particular to a salvage device and method capable of being repeatedly pressed and retreated, the salvage device comprises an upper connector, a sleeve, a connecting neck, a mandrel, a connecting sleeve, a reset spring, a slip, a valve seat and a valve element assembly, the sleeve is fixedly installed on the outer side of the lower end of the upper connector, and the connecting neck is fixedly installed in the center of the lower end of the lower connector; the method comprises the following steps: (1) entering a well, namely entering the retreating type salvaging device capable of being repeatedly pressed into the well, descending to a fish falling position, and starting a pump to circulate at a position close to a fish falling head; the fish retreating valve is reasonable and compact in structure and ingenious in conception, by arranging the upper sealing ring table and the lower sealing ring table, when the valve element assembly moves upwards to block the lower end, liquid in the mandrel enters the area between the upper sealing ring table and the lower sealing ring table through the fish retreating communicating hole and acts on the lower side of the upper sealing ring table, and therefore fish retreating operation is achieved; an upper taper hole is formed, so that the slips lock the fish; and by arranging the lower taper hole, the fish can be conveniently introduced into the slip, and the device has the characteristics of rapidness, stability and high efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of downhole salvage, and relates to a repeatedly pressurized and retractable salvage device and method. Background Art

[0002] With the rapid development of oilfield development technology in my country, various well repair tools have also developed rapidly. Problems often occur during the development process. During the normal development of oil and water wells, various well tools need to be put into the well for well repair operations. During the construction, drill sticking, sand buried pipe string, acid attack and fracture of tools may occur, which may easily cause the tool to fall off. At this time, it is necessary to salvage the tools in the well to restore the oil and water wells to continue production.

[0003] At present, the tools for salvaging the well are generally salvaged with a slip salvage tube. This salvage tool cannot be detached after catching the fish in the well. Only after being lifted to the ground and the internal parts are disassembled can the salvaged tool be separated from the salvage tube. When the fish is stuck and cannot be lifted out, the jam cannot be unstuck and the only way to unstuck it is to use a hard lifting method. This method will make the salvage work more difficult, increase the salvage workload, and increase the cost of restoring oil and water well production. In severe cases, the oil and water wells will be scrapped, resulting in significant economic losses. In addition, the existing salvage tools rely on the fish head to block the circulation channel and the pump pressure to increase to judge the degree of fish entry. The pump pressure on the ground does not change significantly, resulting in inaccurate judgment of the degree of fish entry. Summary of the invention

[0004] The present invention provides a reproducible pressure-retractable salvaging device and method, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problem that the existing salvaging tools cannot be effectively unstuck after being stuck by a fallen fish.

[0005] One of the technical solutions of the present invention is achieved through the following measures: a reproducible pressurizable and retractable salvage device, comprising an upper joint, a sleeve, a connecting neck, a core shaft, a connecting sleeve, a reset spring, a slip, a valve seat and a valve core assembly, wherein a sleeve is fixedly installed on the outer side of the lower end of the upper joint, a connecting neck is fixedly installed on the center of the lower end of the lower joint, a core shaft is fixedly installed on the inner side of the lower end of the connecting neck, a connecting sleeve is sleeved on the outer side of the lower end of the core shaft, a reset spring is arranged on the outer side of the connecting neck, the lower end of the reset spring abuts against the upper end of the connecting sleeve, and the upper end of the reset spring abuts against the lower end of the upper joint An upper sealing ring platform is provided on the inner side of the upper end of the connecting sleeve, a lower sealing ring platform is provided on the outer side of the lower end of the core shaft, and a number of fish-retracting connecting holes that penetrate inside and outside are provided along the circumference at intervals on the outer side of the lower part of the core shaft corresponding to the position between the upper sealing ring platform and the lower sealing ring platform; an upper tapered hole and a lower tapered hole are provided on the lower end of the sleeve, the upper tapered hole is a frustum hole that is larger at the top and smaller at the bottom, and the lower tapered hole is a frustum hole that is smaller at the top and larger at the bottom, and a slip is fixedly installed on the outer side of the lower end of the connecting sleeve; a valve seat is fixedly installed on the inner side of the lower end of the core shaft, and a valve core assembly is provided in the valve seat that can block the lower end of the core shaft when it moves upward.

[0006] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The above-mentioned valve core assembly may include a valve stem and a C-shaped ring, a valve seat is provided with a valve stem with its lower end located below it, a mounting ring groove is provided on the outer side of the upper part of the valve stem, a C-shaped ring is provided in the mounting ring groove, a hanging ring groove is provided on the inner side of the valve seat corresponding to the position of the C-shaped ring, the hanging ring groove includes an upper ring groove and a lower ring groove, and the upper ring groove is in the shape of a truncated cone with a smaller upper part and a larger lower part; a connecting blind hole opening upward is provided on the upper end of the valve stem, a plurality of internal connecting holes that can be connected to the connecting blind hole are provided along the circumference at intervals on the outer side of the middle part of the valve stem corresponding to the position of the connecting blind hole, a connecting ring groove is provided on the inner side of the valve seat corresponding to the position of the internal connecting hole, and external connecting holes that can be connected to the connecting ring groove are provided on the outer side of the valve seat corresponding to the position below the internal connecting hole.

[0007] The valve core assembly may further include a collision head, and the collision head is fixedly mounted on the lower end of the valve stem.

[0008] The above may also include O-rings, at least one O-ring is provided between the core shaft and the connecting neck at an interval of up and down; at least one O-ring is provided between the core shaft and the upper sealing ring platform at an interval of up and down; at least one O-ring is provided between the lower sealing ring platform and the connecting sleeve at an interval of up and down; at least one O-ring is provided between the core shaft and the valve seat at an interval of up and down; at least one O-ring is provided between the valve seat and the valve stem at an interval of up and down.

[0009] The above may also include set screws. At least two set screws are provided at intervals along the circumference on the outer side of the upper end of the slip to fix it to the outer side of the lower end of the connecting sleeve.

[0010] The outer side of the lower end of the above-mentioned upper joint can be fixedly installed with a sleeve through a threaded connection, the inner side of the lower end of the connecting neck can be fixedly installed with a core shaft through a threaded connection, the outer side of the lower end of the connecting sleeve can be fixedly installed with a slip through a threaded connection, and the inner side of the lower end of the core shaft can be fixedly installed with a valve seat through a threaded connection.

[0011] The second technical solution of the present invention is achieved by the following measures: a method of using the above-mentioned reproducible pressure-retractable salvage device, comprising the following steps: (1) Entering the well: The re-pressurizable and retractable fishing device is lowered into the well until the fish is dropped. The pump is turned on near the fish drop head. The circulation channel is kept unobstructed during the lowering process. That is, the liquid can pass through the central channel of the mandrel, the connecting blind hole, the internal connecting hole and the external connecting hole in sequence and then be discharged from the lower end of the sleeve. This ensures that the liquid can circulate normally through the central channel of the mandrel to flush the sand and wash the well; (2) Fish entering: After the fish completely enters the slip, the valve core assembly moves upward, the circulation channel is closed and locked, that is, the inner connecting hole is located above the outer connecting hole. At this time, the liquid cannot be discharged from the lower end of the sleeve through the central channel of the core shaft. The ground shows pressure build-up, the return spring is compressed, the lower end of the slip is located above the upper cone hole, and the slip opens; (3) Salvage: Lift the pipe string, and the reset spring pushes the slip downward. The slip anchors the fish under the action of the upper cone hole. Under the combined action of the elastic force of the reset spring and the gravity of the fish, the slip holds the fish tightly. The heavier the fish, the tighter the slip will hold it until it is lifted to the wellhead. (4) Fish withdrawal: After the slips lock the fish, the fish cannot be withdrawn by lifting the pipe string. The pump is turned on for circulation. The liquid produces a pressure drop under the throttling of the fish withdrawal connecting hole. The internal pressure is greater than the external pressure of the tool and acts on the lower side of the upper sealing ring platform, compressing the reset spring. The slips move upward with the connecting sleeve and open again, discarding the fish. (5) Re-salvage: lift the pipe string and replace other salvage tools, or rotate the pipe string to adjust the fish introduction position and repeat the above steps (2) to (4) until the fish is salvaged.

[0012] The present invention has a reasonable and compact structure and an ingenious conception. By arranging an upper sealing ring platform and a lower sealing ring platform, when the valve core assembly moves upward to block the lower end, the liquid in the core shaft enters into the area between the upper sealing ring platform and the lower sealing ring platform through the fish withdrawal connecting hole, and acts on the lower side of the upper sealing ring platform, thereby realizing the fish withdrawal operation; by arranging an upper tapered hole, the slip valve can hold the fallen fish; by arranging a lower tapered hole, it is convenient to introduce the fallen fish into the slip valve, and the invention has the characteristics of being fast, stable and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Attached Figure 1 It is a schematic diagram of the front cross-sectional structure of embodiments 1 to 7 of the present invention.

[0014] Attached Figure 2 For attachment Figure 1 Schematic diagram of the enlarged structure of the main view of the valve seat and valve core assembly.

[0015] Attached Figure 3 It is a schematic diagram of the main cross-sectional structure in the fish-entering state in Example 7.

[0016] Attached Figure 4 It is a schematic diagram of the main cross-sectional structure in the salvage state in Example 7.

[0017] Attached Figure 5 It is a schematic diagram of the main cross-sectional structure in the fish retreating state in Example 7.

[0018] The codes in the accompanying drawings are: 1 is an upper joint, 2 is a sleeve, 3 is a connecting neck, 4 is a core shaft, 5 is a connecting sleeve, 6 is a reset spring, 7 is a slip, 8 is a valve seat, 9 is an upper sealing ring platform, 10 is a lower sealing ring platform, 11 is a fish withdrawal connecting hole, 12 is an upper tapered hole, 13 is a lower tapered hole, 14 is a valve stem, 15 is a C-ring, 16 is an upper ring groove, 17 is a lower ring groove, 18 is a connecting blind hole, 19 is an inner connecting hole, 20 is an outer connecting hole, 21 is a collision head, 22 is an O-ring, 23 is a set screw, 24 is a connecting ring groove, and 25 is a fish drop. DETAILED DESCRIPTION

[0019] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0020] In the present invention, for the convenience of description, the relative position relationship of each component is described according to the attached Figure 1 The layout is described in detail, such as the positional relationship of front, back, top, bottom, left, right, etc., which is based on the attached manual. Figure 1 The layout direction is determined by the

[0021] The present invention will be further described below in conjunction with embodiments and drawings: Embodiment 1: As attached Figures 1 to 5As shown, the re-pressurizable and retractable salvage device comprises an upper joint 1, a sleeve 2, a connecting neck 3, a core shaft 4, a connecting sleeve 5, a reset spring 6, a slip 7, a valve seat 8 and a valve core assembly. The sleeve 2 is fixedly installed on the outer side of the lower end of the upper joint 1, the connecting neck 3 is fixedly installed on the center of the lower end of the lower joint, the core shaft 4 is fixedly installed on the inner side of the lower end of the connecting neck 3, the connecting sleeve 5 is sleeved on the outer side of the lower end of the core shaft 4, the outer side of the connecting neck 3 is provided with a reset spring 6 whose lower end abuts against the upper end of the connecting sleeve 5, the upper end of the reset spring 6 abuts against the lower end of the upper joint 1, and the upper end of the connecting sleeve 5 is provided with an upper seal A sealing ring platform 9 is provided, and a lower sealing ring platform 10 is provided on the outer side of the lower end of the core shaft 4. A plurality of fish-retracting connecting holes 11 are provided along the circumference at intervals and penetrate inside and outside the lower outer side of the core shaft 4 corresponding to the position between the upper sealing ring platform 9 and the lower sealing ring platform 10; an upper tapered hole 12 and a lower tapered hole 13 are provided on the lower end of the sleeve 2. The upper tapered hole 12 is a truncated cone hole with a larger upper part and a smaller lower part, and the lower tapered hole 13 is a truncated cone hole with a smaller upper part and a larger lower part. A slip 7 is fixedly installed on the outer side of the lower end of the connecting sleeve 5; a valve seat 8 is fixedly installed on the inner side of the lower end of the core shaft 4, and a valve core assembly is provided in the valve seat 8 which can seal the lower end of the core shaft 4 when it goes up. During use, the present invention is put into the well and lowered to the fish landing position. The pump circulation is started near the fish landing head position. The circulation channel is kept unobstructed during the lowering to ensure that the liquid can circulate normally through the central channel of the core shaft 4 to flush the sand and wash the well. After the fish completely enters the slip 7, the valve core assembly moves up, the circulation channel is closed and locked, the ground shows pressure buildup, the reset spring 6 is compressed, the lower end of the slip 7 is located above the upper tapered hole 12, the slip 7 is opened, the pipe column is lifted, the reset spring 6 pushes the slip 7 downward, and the slip 7 anchors the fish under the action of the upper tapered hole 12. Under the combined action of the elastic force of the reset spring 6 and the gravity of the fish, the slip 7 holds the fish. The heavier the fish, the tighter the slip 7 will hold it, until it is lifted to the wellhead and the slip 7 holds it. After the fish is dead, if the upper lifting string cannot lift the fish, the pump circulation is started, and the liquid produces a pressure drop under the throttling of the fish withdrawal connecting hole 11. The internal pressure is greater than the external pressure of the tool, and acts on the lower side of the upper sealing ring platform 9, so that the reset spring 6 is compressed, and the cava 7 moves upward with the connecting sleeve 5 and opens again to throw away the fish; in addition, by setting the upper sealing ring platform 9 and the lower sealing ring platform 10, when the valve core assembly moves upward to block the lower end, the liquid in the core shaft 4 can enter the area between the upper sealing ring platform 9 and the lower sealing ring platform 10 through the fish withdrawal connecting hole 11, and act on the lower side of the upper sealing ring platform 9, thereby realizing the fish withdrawal operation; by setting the upper tapered hole 12, the cava 7 can hold the fish; by setting the lower tapered hole 13, it is convenient to introduce the fish into the cava 7.

[0022] The above-mentioned reproducible pressure-retractable salvage device can be further optimized and / or improved according to actual needs: Embodiment 2: As attached Figures 1 to 5As shown, the valve core assembly includes a valve stem 14 and a C-shaped ring 15. The valve seat 8 is provided with a valve stem 14 with its lower end located below it, and a mounting ring groove is provided on the outer side of the upper part of the valve stem 14. The C-shaped ring 15 is provided in the mounting ring groove. A hanging ring groove is provided on the inner side of the valve seat 8 corresponding to the position of the C-shaped ring 15. The hanging ring groove includes an upper ring groove 16 and a lower ring groove 17. The upper ring groove 16 is in the shape of a truncated cone with a small upper part and a large lower part. The upper end of the valve stem 14 is provided with a communicating blind hole 18 with an opening upward, and a plurality of internal communicating holes 19 that can communicate with the communicating blind hole 18 are provided along the circumference at intervals on the outer side of the middle part of the valve stem 14 corresponding to the position of the communicating blind hole 18. A communicating ring groove 24 is provided on the inner side of the valve seat 8 corresponding to the position of the internal communicating hole 19, and an external communicating hole 20 that can communicate with the communicating ring groove 24 is provided on the outer side of the valve seat 8 corresponding to the position below the internal communicating hole 19. During use, an upper annular groove 16 with a smaller upper part and a larger lower part is provided to facilitate the withdrawal of the C-shaped ring 15 from the upper side of the mounting annular groove; a lower annular groove 17 with a straight hole is provided to prevent the C-shaped ring 15 from withdrawing from the lower side of the mounting annular groove; a valve stem 14 with its lower end located below the valve seat 8 is provided in the valve seat 8, so that only when the fish is introduced into the interior of the application and introduced in place, the circulation channel will be completely closed, causing a significant change in the surface pump pressure, thereby accurately judging the degree of fish entry; a connecting annular groove 24 is provided to facilitate the communication between the internal connecting hole 19 and the external connecting hole 20; in addition, in the well entry state, the liquid can pass through the central channel of the core shaft 4, the connecting blind hole 18, the internal connecting hole 19 and the external connecting hole 20 in sequence. 0 and then discharged from the lower end of the sleeve 2, thereby keeping the circulation channel unobstructed, and sand flushing and well washing operations can be carried out to create a good wellbore environment for subsequent salvage operations; in the fish-in state, the valve core moves upward under the action of the falling fish, and closes the circulation channel, creating a good wellbore environment for subsequent salvage operations; in the fish-out state, since the falling fish head contacts with the lower end of the valve stem 14 and provides supporting force, the liquid in the core shaft 4 enters the area between the upper sealing ring platform 9 and the lower sealing ring platform 10 through the fish-out connecting hole 11, and cannot act on the upper side of the lower sealing ring platform 10 to make the connecting sleeve 5 move downward, but can only act on the lower side of the upper sealing ring platform 9 to make the connecting sleeve 5 move upward, so that the lower end of the slip 7 is located above the upper tapered hole 12, that is, the slip 7 is opened to complete the fish withdrawal.

[0023] Embodiment 3: As attached Figures 1 to 5 As shown, the valve core assembly also includes a collision head 21, and the collision head 21 is fixedly installed at the lower end of the valve stem 14. During use, through such a setting, the contact area between the valve stem 14 and the fish head is increased. According to the requirements, the distance between the upper side of the collision head 21 and the lower side of the valve seat 8 is the first distance, and the distance between the inner connecting hole 19 and the upper end of the connecting ring groove 24 is the second distance. The first distance is greater than the second distance, thereby effectively ensuring that the fish is introduced in place and the circulation channel is completely blocked, and the degree of fish entry is accurately judged.

[0024] Embodiment 4: As attached Figures 1 to 5As shown, it also includes an O-ring 22, at least one O-ring 22 is arranged between the core shaft 4 and the connecting neck 3; at least one O-ring 22 is arranged between the core shaft 4 and the upper sealing ring platform 9; at least one O-ring 22 is arranged between the lower sealing ring platform 10 and the connecting sleeve 5; at least one O-ring 22 is arranged between the core shaft 4 and the valve seat 8; at least one O-ring 22 is arranged between the valve seat 8 and the valve stem 14. In use, through such an arrangement, the sealing between the components is ensured, especially to ensure that the liquid enters the area between the upper sealing ring platform 9 and the lower sealing ring platform 10 through the fish withdrawal connecting hole 11, and acts on the lower side of the upper sealing ring platform 9, thereby realizing the fish withdrawal operation.

[0025] Embodiment 5: As attached Figures 1 to 5 As shown, it also includes a set screw 23, and at least two set screws 23 are arranged at intervals along the circumference of the outer side of the upper end of the slip 7 to fix it to the outer side of the lower end of the connecting sleeve 5. During use, through such an arrangement, the connection between the slip 7 and the connecting sleeve 5 is more stable and reliable.

[0026] Embodiment 6: As attached Figures 1 to 5 As shown, a sleeve 2 is fixedly installed on the outer side of the lower end of the upper joint 1 through a threaded connection, a core shaft 4 is fixedly installed on the inner side of the lower end of the connecting neck 3 through a threaded connection, a slip 7 is fixedly installed on the outer side of the lower end of the connecting sleeve 5 through a threaded connection, and a valve seat 8 is fixedly installed on the inner side of the lower end of the core shaft 4 through a threaded connection. In the process of use, this arrangement facilitates the connection and disassembly of various components.

[0027] Embodiment 7: As attached Figures 1 to 5 As shown, a method of using the above-mentioned re-pressurizable and retractable salvage device comprises the following steps: (1) Entering the well: The re-pressurizable retractable fishing device is lowered into the well until the fish is dropped. The pump is turned on near the fish drop head. The circulation channel is kept unobstructed during the lowering process, that is, the liquid can pass through the central channel of the mandrel 4, the connecting blind hole 18, the internal connecting hole 19 and the external connecting hole 20 in sequence and then be discharged from the lower end of the sleeve 2, ensuring that the liquid can circulate normally through the central channel of the mandrel 4 to flush the sand and wash the well; (2) Fish entering: After the fish completely enters the slip 7, the valve core assembly moves upward, the circulation channel is closed and locked, that is, the inner communication hole 19 is located above the outer communication hole 20. At this time, the liquid cannot be discharged from the lower end of the sleeve 2 through the central channel of the core shaft 4. The ground shows pressure buildup, the return spring 6 is compressed, the lower end of the slip 7 is located above the upper cone hole 12, and the slip 7 opens; (3) Fishing: Lift the pipe string, and the reset spring 6 pushes the slip 7 downward. The slip 7 anchors the fish under the action of the upper cone hole 12. Under the combined action of the elastic force of the reset spring 6 and the gravity of the fish, the slip 7 holds the fish tightly. The heavier the fish, the tighter the slip 7 will hold it until it is lifted to the wellhead. (4) Fish withdrawal: After the slip 7 locks the fish, the fish cannot be withdrawn by lifting the pipe string. The pump is turned on for circulation. The liquid generates a pressure drop under the throttling of the fish withdrawal connecting hole 11. The internal pressure is greater than the external pressure of the tool and acts on the lower side of the upper sealing ring platform 9, compressing the return spring 6. The slip 7 moves upward with the connecting sleeve 5 and opens again, discarding the fish. (5) Re-salvage: lift the pipe string and replace other salvage tools, or rotate the pipe string to adjust the fish introduction position and repeat the above steps (2) to (4) until the fish is salvaged.

[0028] The above technical features constitute the best embodiment of the present invention, which has strong adaptability and best implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A reproducible and retractable salvage device, characterized in that The valve body is provided with a valve cap, a valve stem, a valve cap, a valve cap and a valve core assembly. The valve cap includes an upper joint, a sleeve, a connecting neck, a core shaft, a connecting sleeve, a valve seat and a valve core assembly. The sleeve is fixedly installed on the outer side of the lower end of the upper joint, a connecting neck is fixedly installed in the center of the lower end of the lower joint, a core shaft is fixedly installed on the inner side of the lower end of the connecting neck, a connecting sleeve is sleeved on the outer side of the lower end of the core shaft, a reset spring is arranged on the outer side of the connecting neck, the lower end of the reset spring is abutted against the upper end of the connecting sleeve, an upper sealing ring platform is arranged on the inner side of the upper end of the connecting sleeve, a lower sealing ring platform is arranged on the outer side of the lower end of the core shaft, and a plurality of fish-retracting connecting holes that are connected inside and outside are arranged at intervals along the circumference on the outer side of the lower part of the core shaft corresponding to the position between the upper sealing ring platform and the lower sealing ring platform; an upper conical hole and a lower conical hole are arranged on the lower end of the sleeve, the upper conical hole is a truncated cone hole that is larger at the top and smaller at the bottom, and the lower conical hole is a truncated cone hole that is smaller at the top and larger at the bottom, and a slip is fixedly installed on the outer side of the lower end of the connecting sleeve; a valve seat is fixedly installed on the inner side of the lower end of the core shaft, and a valve core assembly that can block the lower end of the core shaft when it goes up is arranged in the valve seat.

2. The re-pressurizable and retractable salvage device according to claim 1, characterized in that The valve core assembly includes a valve stem and a C-shaped ring. A valve stem with its lower end located below the valve seat is provided in the valve seat. A mounting ring groove is provided on the outer side of the upper part of the valve stem. A C-shaped ring is provided in the mounting ring groove. A hanging ring groove is provided on the inner side of the valve seat corresponding to the position of the C-shaped ring. The hanging ring groove includes an upper ring groove and a lower ring groove. The upper ring groove is in the shape of a truncated cone with a smaller upper part and a larger lower part. A connecting blind hole opening upward is provided on the upper end of the valve stem. A plurality of internal connecting holes that can be connected to the connecting blind hole are provided along the circumference at intervals on the outer side of the middle part of the valve stem corresponding to the position of the connecting blind hole. A connecting ring groove is provided on the inner side of the valve seat corresponding to the position of the internal connecting hole. External connecting holes that can be connected to the connecting ring groove are provided on the outer side of the valve seat corresponding to the position below the internal connecting hole.

3. The re-pressurizable and retractable salvage device according to claim 2, characterized in that The valve core assembly also includes a collision head, and the collision head is fixedly installed at the lower end of the valve stem.

4. The re-pressurizable and retractable salvage device according to claim 1, 2 or 3, characterized in that It also includes an O-ring, wherein at least one O-ring is provided at an interval of up and down between the core shaft and the connecting neck; at least one O-ring is provided at an interval of up and down between the core shaft and the upper sealing ring platform; at least one O-ring is provided at an interval of up and down between the lower sealing ring platform and the connecting sleeve; at least one O-ring is provided at an interval of up and down between the core shaft and the valve seat; and at least one O-ring is provided at an interval of up and down between the valve seat and the valve stem.

5. The re-pressurizable and retractable salvage device according to claim 1, 2 or 3, characterized in that It also includes fixing screws. At least two fixing screws are arranged at intervals along the circumference on the outer side of the upper end of the slip to fix it with the outer side of the lower end of the connecting sleeve.

6. The re-pressurizable and retractable salvage device according to claim 4, characterized in that It also includes fixing screws. At least two fixing screws are arranged at intervals along the circumference on the outer side of the upper end of the slip to fix it with the outer side of the lower end of the connecting sleeve.

7. The re-pressurizable and retractable salvaging device according to claim 1, 2, 3 or 6, characterized in that A sleeve is fixedly installed on the outer side of the lower end of the upper joint through a threaded connection, a core shaft is fixedly installed on the inner side of the lower end of the connecting neck through a threaded connection, a slip is fixedly installed on the outer side of the lower end of the connecting sleeve through a threaded connection, and a valve seat is fixedly installed on the inner side of the lower end of the core shaft through a threaded connection.

8. The re-pressurizable and retractable salvage device according to claim 4, characterized in that A sleeve is fixedly installed on the outer side of the lower end of the upper joint through a threaded connection, a core shaft is fixedly installed on the inner side of the lower end of the connecting neck through a threaded connection, a slip is fixedly installed on the outer side of the lower end of the connecting sleeve through a threaded connection, and a valve seat is fixedly installed on the inner side of the lower end of the core shaft through a threaded connection.

9. The re-pressurizable and retractable salvage device according to claim 5, characterized in that A sleeve is fixedly installed on the outer side of the lower end of the upper joint through a threaded connection, a core shaft is fixedly installed on the inner side of the lower end of the connecting neck through a threaded connection, a slip is fixedly installed on the outer side of the lower end of the connecting sleeve through a threaded connection, and a valve seat is fixedly installed on the inner side of the lower end of the core shaft through a threaded connection.

10. A method for repeatedly pressing and retracting a salvaging device according to any one of claims 2 to 9, characterized in that The steps include: (1) Entering the well: The re-pressurizable and retractable fishing device is lowered into the well until the fish is dropped. The pump is turned on near the fish drop head. The circulation channel is kept unobstructed during the lowering process. That is, the liquid can pass through the central channel of the mandrel, the connecting blind hole, the internal connecting hole and the external connecting hole in sequence and then be discharged from the lower end of the sleeve. This ensures that the liquid can circulate normally through the central channel of the mandrel to flush the sand and wash the well; (2) Fish entering: After the fish completely enters the slip, the valve core assembly moves upward, the circulation channel is closed and locked, that is, the inner connecting hole is located above the outer connecting hole. At this time, the liquid cannot be discharged from the lower end of the sleeve through the central channel of the core shaft. The ground shows pressure build-up, the return spring is compressed, the lower end of the slip is located above the upper cone hole, and the slip opens; (3) Salvage: Lift the pipe string, and the reset spring pushes the slip downward. The slip anchors the fish under the action of the upper cone hole. Under the combined action of the elastic force of the reset spring and the gravity of the fish, the slip holds the fish tightly. The heavier the fish, the tighter the slip will hold it until it is lifted to the wellhead. (4) Fish withdrawal: After the slips lock the fish, the fish cannot be withdrawn by lifting the pipe string. The pump is turned on for circulation. The liquid produces a pressure drop under the throttling of the fish withdrawal connecting hole. The internal pressure is greater than the external pressure of the tool and acts on the lower side of the upper sealing ring platform, compressing the reset spring. The slips move upward with the connecting sleeve and open again, discarding the fish. (5) Re-salvage: lift the pipe string and replace other salvage tools, or rotate the pipe string to adjust the fish introduction position and repeat the above steps (2) to (4) until the fish is salvaged.

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