Reverse circulation hydraulic power-assisted one-grip fisher
By designing a reverse circulation hydraulically assisted one-handed retrieval device, reverse circulation of well fluid and protection of the gripping teeth are achieved, solving the problems of high retrieval difficulty and easy deformation of the gripping teeth in the existing technology, and improving the retrieval success rate and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- MUDANJIANG AOTAI REFINING TECH CO LTD
- Filing Date
- 2025-06-09
- Publication Date
- 2026-04-28
AI Technical Summary
The existing single-grip retrieval tool has several drawbacks when retrieving fish that have fallen into the well. These drawbacks include increased difficulty in retrieval due to the fish being eccentrically attached to the well wall, and easy deformation of the gripping teeth. Furthermore, it lacks an effective well fluid circulation assist function, resulting in a high failure rate in retrieval.
A reverse circulation hydraulically assisted grabber was designed. By hiding the grab teeth at the bottom of the grabbing cylinder, the grabber is converted to a grabbing state by hydraulic drive, forming a reverse circulation flow of well fluid to help the fish get away from the well wall. The grab teeth are protected under the basic structure to avoid collision.
It improved the salvage effect, reduced the salvage difficulty, enhanced the safety and reliability of the salvage device, ensured that the gripping teeth were not easily deformed, and improved the salvage success rate.
Smart Images
Figure CN224174055U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of oilfield salvage technology, specifically to a reverse circulation hydraulically assisted one-handed salvage device. Background Technology
[0002] The one-grab retrieval tool is a widely used retrieval tool in oilfield downhole operations. It is mainly used to retrieve irregular small non-magnetic objects that have fallen into the well. Its working principle is to cover the fallen object inside the grabbing teeth or between the grabbing teeth, and use the rotating and lowered tubing string to bend and twist the grabbing teeth. Through the plastic deformation of the grabbing teeth, the object is gripped or locked in place, thus retrieving the object from the well. It has the characteristics of simple structure, easy operation, and wide applicability. Based on the working principle of the one-grab fishing tool, it is known that in order to cover the fallen fish with the grabbing teeth during the fishing process, the grabbing teeth must be inserted between the fallen fish and the well wall. Obviously, the fallen fish being in an eccentric state against the well wall will increase the difficulty of fishing with the one-grab fishing tool. The normally circulating mud fluid is pumped into the central shaft hole of the tubing string and then flows back from the external space of the tubing string. The flow direction in the downhole obviously tends to push the fallen fish towards the well wall, which is obviously not conducive to the one-grab fishing tool grabbing the fallen fish. Therefore, when using the one-grab fishing tool to fish, except for flushing the fallen fish with circulating well fluid to remove the mud and sand deposited on the fallen fish when necessary before fishing, fishing is usually carried out under the condition of no well fluid circulation. Although this can avoid interference and impact on the fishing process, at the same time, due to the lack of supporting means and measures to coordinate the intervention, the difficulty of fishing the downhole fish that is initially in an eccentric state against the well wall cannot be alleviated or improved, and fishing failures have occurred in production. Meanwhile, in existing single-grip fishing devices, the gripping teeth are fixedly connected to the tubing string (lower end) in an external position. During the retrieval process, there is a risk of accidental collision with the well wall, causing the gripping teeth to deform and lose their retrieval function, resulting in retrieval failure and accidents. Based on the above problems, it is necessary to research and improve existing single-grip fishing devices, optimize their design structure, improve their supporting functions, and enhance retrieval efficiency. Utility Model Content
[0003] The purpose of this invention is to provide a reverse circulation hydraulically assisted grabber, equipped with a well fluid reverse circulation assist function and a hidden protection function for the grab teeth, thereby enhancing the safety and reliability of production and use, and improving the grabbing effect.
[0004] A reverse-circulation hydraulically assisted grabber includes: an upper connector, a grabbing cylinder, a protective sleeve, a piston sleeve, a limiting sleeve, and a delivery steel ball; both the upper connector and the protective sleeve are cylindrical structures. The upper end of the upper connector is provided with an internal thread for connection to a drill pipe string, and the lower end is fixedly connected to the protective sleeve. A limiting guide groove is formed on the inner circumferential surface of the protective sleeve, perpendicularly arranged along the axial direction. The diameter of the lower region of the central shaft hole of the upper connector is larger than the diameter of the upper region, forming an annular shoulder between the lower and upper regions. An annular limiting groove is formed on the inner circumferential surface of the lower end of the lower region. The piston sleeve is disposed on the upper connector. The head has a piston head with an increased diameter at the upper end within the central shaft hole. The piston head forms a sealing fit with the inner circumferential surface of the upper region of the central shaft hole. The sleeve of the piston sleeve forms an annular space with the circumferential surface of the upper region of the central shaft hole. A limiting sleeve is disposed in the upper region of the central shaft hole, fixedly connected to the upper connector, and fitted around the sleeve of the piston sleeve. The limiting sleeve not only seals the annular space but also corresponds to the piston head to limit the axial travel distance of the piston sleeve. The cylinder of the retrieval tube is disposed in the lower region of the central shaft hole of the upper connector and fixedly connected to the lower end of the piston sleeve, with its upper outer circumferential surface... An annular insert groove is formed, corresponding to the annular limiting groove structure formed on the inner circumference of the upper connector. An elastic retaining ring is inserted into the annular insert groove. A gripping tooth protrudes from the outer circumference of the cylinder and is evenly distributed along the circumference of the cylinder. The gripping tooth extends into the protective sleeve and is respectively fitted into the limiting guide groove formed on the inner circumference of the protective sleeve. The limiting guide groove can guide the axial movement of the retrieval cylinder and restrict its axial rotation. A downstream channel and a return channel are respectively formed on the upper connector to guide the mud well fluid. The downstream channel extends from the inner circle of the upper region of the central shaft hole of the upper connector. The circumferential surface is connected to the external space of the upper connector. The return channel is connected from the shoulder surface of the annular shoulder to the external space of the upper connector. On the outer circumferential surface of the upper connector, the channel opening of the return channel and the external space is located above the channel opening of the downstream channel and the external space. At the same time, a guide channel is also provided on the retrieval cylinder. The guide channel is connected from the upper end face of the retrieval cylinder body to the interior of the retrieval cylinder body. Between the corresponding shoulder surfaces of the annular shoulder and the upper end face of the retrieval cylinder body, the channel openings of the return channel and the guide channel are staggered to avoid mutual communication.In its basic structural state, the piston head is connected to the upper connector via a shear screw. The upper end face of the retrieval cylinder corresponds to and engages with the shoulder face of the annular shoulder. The upper end face of the retrieval cylinder closes the opening of the return channel on the shoulder face of the annular shoulder, while the shoulder face of the annular shoulder closes the opening of the guide channel on the upper end face of the retrieval cylinder. The connecting opening of the downstream channel on the circumferential surface within the upper region of the central shaft hole of the upper connector is constrained within the fully enclosed annular space. The downstream channel, the return channel, and the guide channel... Since the flow channels cannot facilitate the participation of mud and well fluid in well fluid circulation, the aforementioned reverse circulation hydraulically assisted grabber maintains a conventional well fluid circulation structure. In the retrieval configuration, the deployed steel ball sets and seals the central fluid flow channel of the piston sleeve, the shear screw is sheared, and the connection between the piston sleeve and the upper connector is released. The piston sleeve and the retrieval cylinder move downward relative to the upper connector until the annular groove on the retrieval cylinder and the annular limiting groove on the upper connector correspond and overlap. The elastic expansion portion of the elastic retaining ring is embedded in the annular limiting groove and locked in place. The connection structure between the retrieval cylinder and the upper connector is such that, at this time, the upper end face of the retrieval cylinder body and the shoulder surface of the annular shoulder are separated and no longer in contact. The guide channel opening on the upper end face of the retrieval cylinder body and the return channel opening on the shoulder surface of the annular shoulder are simultaneously opened. The downstream channel connection opening on the circumferential surface within the upper region of the central shaft hole of the upper connector is also simultaneously released from the constraint of the annular space and directly connected to the central shaft hole. This forms a flow of mud well fluid from the central shaft hole of the upper connector through the downstream channel. The well fluid reverse circulation structure, consisting of the channel, the interior of the retrieval cylinder, the guide channel, the return channel, and finally the well fluid flowing back to the surface from the external space of the upper connector, allows the mud well fluid to form a flow direction opposite to that in the conventional well fluid circulation structure in the lower port area of the retrieval cylinder. That is, the mud well fluid flows from the external space into the interior of the retrieval cylinder. This reverse circulation of the mud well fluid helps to impact and move the eccentrically attached fish downhole away from the well wall, or to center it, thereby effectively reducing the difficulty of the grabbing teeth in grasping the fish downhole and improving the retrieval effect.
[0005] The aforementioned reverse circulation hydraulic-assisted one-handed grabber, preferably in its basic structural state, has the grab teeth, located at the lower part of the grabbing cylinder, entirely concealed within the protective sleeve. In the grabbing structure state, when the grabbing cylinder moves downward relative to the protective sleeve, the grab teeth concealed within the protective sleeve can be fully extended, presenting a grabbing structure state for fish falling into the well. During the grabbing operation, the drill string can be sent in the basic structural state of the reverse circulation hydraulic-assisted one-handed grabber, protecting the grab teeth. Once the drill string is sent to the grabbing operation area, hydraulic drive is used to transform the basic structural state into the grabbing structure state to retrieve the fish falling into the well. This avoids potential collision damage to the grab teeth during the drill string's descent, ensuring the safety and reliability of the grabbing operation.
[0006] The aforementioned reverse circulation hydraulically assisted grabber preferably has the same total flow capacity in the downstream channel and the return channel opened on the upper connector and the guide channel opened on the grabber cylinder, so as to avoid structural bottlenecks in the well fluid reverse circulation structure formed in the grabber structure state, which would affect the continuity and smoothness of the mud well fluid circulation.
[0007] The aforementioned reverse circulation hydraulically assisted grabber preferably has the same number of downstream channels, return channels, and guide channels, with the same flow capacity per channel, and their positions correspond to each other. These channels are evenly distributed along the circumference of the upper connector and the grabber cylinder, respectively, to improve the uniformity of the mud well fluid flow along the circumference of the upper connector and the grabber cylinder. This maintains the mud well fluid in a stable longitudinal flow state, improves the uniformity of the circumferential distribution of the mud well fluid flow when it flows concentrically from the outer circumference of the grabber cylinder to the lower port area, reduces turbulence tendency, and enhances the stability and continuity of the mud well fluid flowing in the reverse circulation direction, keeping the fish impacted and separated from the well wall in a centered position. Hydraulic assistance further improves the grabbing effect.
[0008] The aforementioned reverse circulation hydraulically assisted grabber preferably has an upper sealing plate fixedly installed on the shoulder surface of the annular shoulder inside the upper connector. The upper sealing plate has correspondingly distributed connecting holes on its disc surface, each communicating with a return channel. A lower sealing plate is fixedly installed on the upper end face of the grabber cylinder. The lower sealing plate has correspondingly distributed connecting holes on its disc surface, each communicating with a guide channel. The upper and lower sealing plates are correspondingly arranged and respectively fitted around the piston sleeve. In this basic structural state, the upper end face of the grabber cylinder and the shoulder surface of the annular shoulder are correspondingly fitted through the contact between the upper and lower sealing plates. Between the contacting upper and lower sealing plates, the upper sealing plate maintains a corresponding seal to the guide channel, and the lower sealing plate maintains a corresponding seal to the return channel, thereby enhancing the reliability of the seal between the guide channel and the return channel in the basic structural state.
[0009] The reverse circulation hydraulically assisted grabber preferably has an alloy layer welded onto the lower end face and the outer circumference of the end of the protective sleeve to improve the impact resistance and wear resistance of the leading area of the protective sleeve.
[0010] The beneficial effects of this utility model are that it provides a reverse circulation hydraulically assisted one-handed retrieval device. Through optimized structural design, it can achieve two structural states: basic and retrieval. In the basic structural state, the retrieval device maintains a conventional well fluid circulation structure, which can wash and clean the sediment and debris deposited on the surface of the fish in the well. After the basic structural state is transformed into the retrieval structural state by the action of well fluid pressure, the well fluid reverse circulation structure is reconstructed through the combination of the smooth channel, the return channel and the guide channel. At the port area of the retrieval cylinder, the mud well fluid will flow from the outer circumference of the oil well wall to the inside of the retrieval cylinder in a reverse circulation motion state. This is conducive to impacting and driving the fish in the well to move away from the oil well wall and towards the center, thereby keeping the fish in the well in a centered state, creating favorable conditions for retrieval, effectively reducing the difficulty of retrieval and improving the retrieval effect. Furthermore, in the basic structural state, the grab teeth on the retrieval cylinder can be completely hidden and housed in a protective sleeve, which protects the grab teeth during the dropping process and prevents them from colliding with the well wall and causing damage, thus affecting the retrieval effect. When transformed into the retrieval structure state, they can be fully extended to realize their function, fully ensuring the safety and reliability of the retrieval operation. Attached Figure Description
[0011] Figure 1 This is a diagram showing the basic structure of a reverse-circulation hydraulically assisted grabber.
[0012] Figure 2 for Figure 1 Sectional view along line AA.
[0013] Figure 3 for Figure 1 Sectional view along the BB line.
[0014] Figure 4 for Figure 1 Sectional view along the CC line.
[0015] Figure 5 for Figure 1 Enlarged view of section I in the middle.
[0016] Figure 6 This is a diagram showing the retrieval structure of a reverse-circulation hydraulically assisted grabber.
[0017] Among them: 1 is the upper connector, 2 is the retrieval tube, 3 is the protective sleeve, 4 is the piston sleeve, 5 is the limiting sleeve, 6 is the delivery steel ball, 7 is the elastic retaining ring, 8 is the upper sealing plate, 9 is the lower sealing plate, 10 is the gripping tooth, 11 is the downstream channel, 12 is the return channel, 13 is the guide channel, 14 is the annular limiting groove, 15 is the alloy layer, 16 is the annular space, and 17 is the shearing screw. Detailed Implementation
[0018] Furthermore, the technical solution for which protection is sought in this utility model will be described in detail below with reference to specific embodiments and accompanying drawings.
[0019] A reverse circulation hydraulically assisted grabber retrieval device, such as Figures 1 to 6 As shown, it consists of an upper connector 1, a retrieval cylinder 2, a protective sleeve 3, a piston sleeve 4, a limiting sleeve 5, a delivery steel ball 6, an elastic retaining ring 7, an upper sealing plate 8, and a lower sealing plate 9.
[0020] The upper connector 1 has an annular shoulder in its central shaft hole. The diameter of the upper region is smaller than that of the lower region, with the annular shoulder as the boundary. A limiting sleeve 5 is fixedly installed at the lower end of the upper region. An annular limiting groove 14 is formed on the inner circumferential surface at the lower end of the lower region. Ten downstream channels 11 and return channels 12 are formed on the sidewalls. The downstream channel 11 is located between the circumferential surface of the upper region of the central shaft hole of the upper connector 1 and the outer circumferential surface of the upper connector 1. The return channel 12 is located between the shoulder surface of the annular shoulder and the outer circumferential surface of the upper connector 1. On the outer circumferential surface of the upper connector 1, the opening of the return channel 12 is higher than the opening of the downstream channel 11. The upstream channel 11 and the downstream channel 12 are configured to have the same diameter, and are staggered and evenly distributed along the circumference of the upper connector 1. An upper sealing plate 8 is fixedly installed on the shoulder surface of the annular shoulder, and the upper sealing plate 8 has corresponding connecting holes on its disc surface that connect the upstream channel 11 and the downstream channel 12. The protective sleeve 3 is fixedly connected to the lower end of the upper connector 1, and has seven axially perpendicular limiting guide grooves evenly distributed along the circumference on its inner circumference. An alloy layer 15 is partially welded to the lower end face and the outer circumference of the end head. The alloy layer 15 is formed by welding tungsten alloy powder using an oxy-acetylene welding process. The piston sleeve 4 consists of a sleeve body and a... The piston head at the upper end of the sleeve is installed in the central shaft hole of the upper connector 1. The piston head and the circumferential surface in the upper region of the central shaft hole form a sealing fit. A setting structure is provided at the upper end, which can be used by the delivery steel ball 6 to set the liquid flow channel inside the piston sleeve 4. The sleeve and the circumferential surface in the upper region of the central shaft hole form an annular space 16. The retrieval cylinder 2 is composed of a cylinder and 7 gripping teeth 10 set at the front end of the cylinder. It is set in the lower region of the central shaft hole of the upper connector 1 and fixedly connected to the lower end of the piston sleeve 4. An annular insert groove is opened at the upper end of the outer circumferential surface of the cylinder. The annular insert groove corresponds to the annular limiting groove 14 opened on the upper connector 1. An elastic retaining ring 7 is embedded in the annular mounting groove. Seven gripping teeth 10 protrude from the outer circumference of the cylinder and are evenly distributed along the circumference of the cylinder. They are respectively fitted into the seven limiting guide grooves opened on the protective sleeve 3. Ten through guide channels 13 are opened on the upper end face of the retrieval cylinder 2. The guide channels 13 have the same circular hole diameter as the return channel 12 and the guide channels 13. Their positions on the annular shoulder are staggered with those of the return channel 12 and are evenly distributed along the cross-sectional circumference of the retrieval cylinder 2. At the same time, a lower sealing plate 9 is fixedly installed on the upper end face of the retrieval cylinder 2. The disc surface of the lower sealing plate 9 has corresponding connecting holes that connect to the guide channels 13.
[0021] In production, the reverse circulation hydraulically assisted one-handed grabber described in this embodiment is used. First, as follows: Figures 1 to 5 As shown, the reverse circulation hydraulically assisted grabber is connected to the drill string and lowered into the well in its basic structural state. In this basic structural state, the piston head on the piston sleeve 4 is connected to the upper connector 1 via shear screws 17. The upper end face of the grabber cylinder 2 is in contact with the shoulder surface of the annular shoulder inside the upper connector 1. The connecting port of the downstream channel 11 on the circumferential surface in the area above the central shaft hole of the upper connector 1 is constrained in the annular space 16. The grabber teeth 10 on the grabber cylinder 2... All components are concealed within the protective sleeve 3. When the drill string is lowered to the retrieval depth, the pump is started to circulate the mud well fluid. After flushing and cleaning the sediment and debris deposited on the surface of the fish in the well, the pump is stopped to cease the circulation of the mud well fluid. A delivery steel ball 6 is then inserted into the water hole of the drill string, causing the delivery steel ball 6 to fall and seal the liquid flow channel opening of the piston sleeve 4. The pump is then started again to pump the mud well fluid. As the well fluid pressure gradually increases, the well fluid pressure will push the piston sleeve 4 to shear the shear line. The cutting screw 17 moves downward relative to the upper connector 1 along with the retrieval cylinder 2. As the piston sleeve 4 and the retrieval cylinder 2 move, the annular space 16 is gradually compressed axially. When the piston head moves to below the connecting hole opened on the inner circumferential surface of the downstream channel 11, the two ends of the downstream channel 11 are interconnected. At the same time, the upper sealing plate 8 and the lower sealing plate 9 separate, and the sealing state of the connecting ports of the guide channel 13 and the return channel 12 is released. The guide channel 13 and the return channel 12 are also connected at the same time. The gripping teeth 10 also begin to extend from the lower port of the protective sleeve 3 until the annular insert groove on the retrieval cylinder 2 and the annular limiting groove 14 on the upper connector 1 correspond to each other and overlap. The elastic retaining ring 12, which is embedded in the annular limiting groove 14, locks the connection between the retrieval cylinder 2 and the upper connector 1. The movement of the piston sleeve 4 and the retrieval cylinder 2 terminates. Figure 6As shown, the reverse circulation hydraulically assisted grabber transforms into a grabbing structure state. At this time, the grabbing teeth 10 have fully extended from the protective sleeve 3. In the grabbing structure state, since the downstream channel 11, the return channel 12, and the guide channel 13 are all open, the pumping pressure of the mud well fluid is maintained. At the lower port area of the grabbing cylinder, the mud well fluid will form a reverse circulation motion state, flowing from the outer circumference of the well wall to the inside of the grabbing cylinder 2. This reverse circulation flow of the mud well fluid... Obviously, the impact will cause the fish that fell into the well to move away from the well wall and towards the center. This may keep the fish in a centered position under the continuous action of a balanced and stable fluid flow, creating favorable conditions for retrieval. After that, once the flow of the mud fluid stabilizes, the fish can be retrieved while maintaining fluid circulation. This involves slowly rotating the drill string while applying a certain amount of pressure. Once it is confirmed that the gripper 10 has successfully grabbed the fish, the pumping of mud fluid into the well is stopped, and the drill string is lifted until it exits the well, thus completing the retrieval operation.
Claims
1. A reverse-circulation hydraulically assisted one-handed retrieval device, characterized in that, include: The upper connector (1), the retrieval cylinder (2), the protective sleeve (3), the piston sleeve (4), the limiting sleeve (5), and the delivery steel ball (6) are all cylindrical structures. The upper end of the upper connector (1) is provided with an internal thread, and the lower end is fixedly connected to the protective sleeve (3). A limiting guide groove is provided on the inner circumferential surface of the protective sleeve (3) and is arranged vertically along the axial direction. The diameter of the lower region of the central shaft hole of the upper connector (1) is larger than the diameter of the upper region, forming an annular shoulder between the lower region and the upper region. An annular limiting groove (14) is provided on the inner circumferential surface of the lower end of the lower region. The piston sleeve (4) is set in the... In the central shaft hole of the upper connector (1), the upper end has a piston head with an increased diameter. The piston head and the inner circumferential surface of the upper region of the central shaft hole form a sealing fit. The sleeve of the piston sleeve (4) and the circumferential surface of the upper region of the central shaft hole form an annular space (16). The limiting sleeve (5) is set in the upper region of the central shaft hole, fixedly connected to the upper connector (1), and fits around the sleeve of the piston sleeve (4). The cylinder of the retrieval tube (2) is set in the lower region of the central shaft hole of the upper connector (1) and fixedly connected to the lower end of the piston sleeve (4). The upper outer circumferential surface is opened with the openings that are opened on the inner circumferential surface of the upper connector (1). The annular limiting groove (14) has corresponding annular insert grooves. An elastic retaining ring (7) is inserted in the annular insert groove. The lower part is provided with gripping teeth (10) that protrude from the outer circumferential surface of the cylinder and are evenly distributed along the circumference of the cylinder. The gripping teeth (10) extend into the protective sleeve (3) and are respectively fitted into the limiting guide grooves opened on the inner circumferential surface of the protective sleeve (3). A downstream channel (11) and a return channel (12) are respectively opened on the upper connector (1). The downstream channel (11) connects from the inner circumferential surface of the upper region of the central shaft hole of the upper connector (1) to the external space of the upper connector (1). The return channel (12) The return channel (12) is connected to the outer space of the upper connector (1) from the shoulder surface of the annular shoulder. On the outer circumference of the upper connector (1), the channel opening of the return channel (12) and the outer space is set at the upper part of the channel opening of the downstream channel (11) and the outer space. At the same time, a guide channel (13) is also provided on the salvage cylinder (2). The guide channel (13) is connected from the upper end face of the salvage cylinder (2) to the inside of the salvage cylinder (2). Between the shoulder surface of the annular shoulder and the upper end face of the salvage cylinder (2), the channel openings of the return channel (12) and the guide channel (13) are staggered.In the basic structural state, the piston head is connected to the upper connector (1) via a shear screw (17). The upper end face of the retrieval cylinder (2) is in contact with the shoulder face of the annular shoulder. The upper end face of the retrieval cylinder (2) closes the channel opening of the return channel (12) on the shoulder face of the annular shoulder. The shoulder face of the annular shoulder closes the channel opening of the guide channel (13) on the upper end face of the retrieval cylinder (2). The connecting port of the downstream channel (11) on the circumferential surface in the upper region of the central shaft hole of the upper connector (1) is constrained in the fully enclosed annular space (16). In the retrieval structure state, the delivery steel ball (6) sets and seals the central liquid flow channel of the piston sleeve (4). The shear screw (17) is sheared. The annular insert groove on the retrieval cylinder (2) and the annular limiting groove (14) on the upper connector (1) correspond to each other and overlap. The elastic retaining ring ( 7) The connection structure between the retrieval cylinder (2) and the upper connector (1) is locked in the annular limiting groove (14) embedded in the elastic expansion part. The upper end face of the retrieval cylinder (2) is separated from the shoulder face of the annular shoulder. The channel opening of the guide channel (13) on the upper end face of the retrieval cylinder (2) and the channel opening of the return channel (12) on the shoulder face of the annular shoulder are opened at the same time. The connecting port of the downstream channel (11) on the circumferential surface in the upper region of the central shaft hole of the upper connector (1) is also released from the constraint of the annular space (16) and directly connected to the central shaft hole. This forms a reverse circulation structure for the well fluid, which flows from the central shaft hole of the upper connector (1) through the downstream channel (11), the inside of the retrieval cylinder (2), the guide channel (13), and the return channel (12), and finally flows back to the ground from the external space of the upper connector (1).
2. The reverse circulation hydraulically assisted one-handed retrieval device as described in claim 1, characterized in that: In the basic structural state, the gripping teeth (10) located at the lower part of the retrieval tube (2) are completely hidden and housed in the protective sleeve (3). In the retrieval structural state, the retrieval tube (2) moves downward relative to the protective sleeve (3), and the gripping teeth (10) hidden and housed in the protective sleeve (3) can be fully extended.
3. The reverse circulation hydraulically assisted one-handed retrieval device as described in claim 2, characterized in that: The downstream channel (11) and the return channel (12) opened on the upper connector (1) and the guide channel (13) opened on the retrieval cylinder (2) have the same total flow capacity.
4. The reverse circulation hydraulically assisted one-handed retrieval device as described in claim 3, characterized in that: The number of the downstream channel (11), the return channel (12) and the guide channel (13) are the same, the single channel flow rate is the same, and their positions correspond to each other. They are evenly distributed along the cross-sectional circumference of the upper connector (1) and the retrieval tube (2).
5. A reverse circulation hydraulically assisted one-handed retrieval device as described in any one of claims 1 to 4, characterized in that: An upper sealing plate (8) is fixedly installed on the shoulder surface of the annular shoulder inside the upper connector (1). A connecting hole, corresponding to each of the return channels (12), is provided on the disc surface of the upper sealing plate (8). A lower sealing plate (9) is fixedly installed on the upper end face of the retrieval cylinder (2). A connecting hole, corresponding to each of the guide channels (13), is provided on the disc surface of the lower sealing plate (9). The upper sealing plate (8) and the lower sealing plate (9) are correspondingly arranged and respectively... The fitting ring is sleeved on the piston sleeve (4). In the basic structural state, the upper end face of the retrieval cylinder (2) and the shoulder face of the annular shoulder are correspondingly fitted through the mutual contact between the upper sealing plate (8) and the lower sealing plate (9). Between the mutually contacting upper sealing plate (8) and the lower sealing plate (9), the upper sealing plate (8) maintains a corresponding seal to close the guide channel (13), and the lower sealing plate (9) maintains a corresponding seal to close the return channel (12).
6. The reverse circulation hydraulically assisted one-handed retrieval device as described in claim 5, characterized in that: An alloy layer (15) is welded onto the lower end face and the outer circumference of the end of the protective sleeve (3).