A fishing device and method

Abstract

The application discloses a fishing device and a fishing method, and belongs to the technical field of downhole operation. The fishing device comprises a fishing tool, a magnetic detector and a leading shoe which are connected in sequence. The magnetic detector comprises a sealed cavity formed by a coaxial sleeve of a shell and an inner cylinder, a perforated ball head which is coaxially sleeved on the outer wall of the inner cylinder, a ball socket which is sleeved on the outer wall of the perforated ball head and combined into a ball hinge structure, an inner wall of the ball socket and a key groove of the perforated ball head are in sliding connection, the ball socket can only rotate along the longitudinal section of the ball socket, a Halbach array permanent magnet which is fixedly connected with the ball socket, a plurality of force sensors which are arranged in an annular array on the inner cylinder, and each force sensor is fixedly connected with the Halbach array permanent magnet through an elastic element. The fishing device can realize the judgment of the fish top attitude, significantly improve the centering accuracy and the one-time fishing success rate, thereby effectively shortening the operation cycle and reducing the non-production time.

Description

Technical Field

[0001] This invention relates to the field of downhole operation technology, specifically to a retrieval device and method for retrieving fish that have fallen into wells. Background Technology

[0002] During drilling, completion, and workover of oil and gas wells, drilling tools and downhole equipment are prone to breakage or detachment due to factors such as equipment fatigue, operational deviations, or sudden geological changes, resulting in "fish" (drill bits falling off the well). This type of failure is particularly common in directional wells, highly deviated wells, and horizontal wells. Because the "fish" tends to lean against the wellbore under the combined effects of gravity and wellbore friction, the posture of the "fish" top (fracture, opening, or misalignment) becomes complex and variable. This not only disrupts normal drilling operations but may also induce complex risks such as stuck pipe and wellbore collapse. Therefore, the core prerequisite for efficient and safe fishing operations is the rapid and reliable identification and positioning of the "fish" top's spatial location, tilt direction, and contact state with the wellbore.

[0003] Currently, the methods used in the industry for recovering fallen fish are mainly divided into several categories, all of which have obvious technical limitations:

[0004] Firstly, a "blind retrieval" method is employed, where, lacking precise information about the exact location, attitude, and shape of the fish's top, the operator relies solely on experience to select retrieval tools such as retrieval tubes, retrieval spears, or strong magnetic tools for exploratory retrieval. When using retrieval tubes or spears, the retrieval tool and drilling plan are selected based on well depth, approximate fracture location, logging data, and wellhead parameters. The tool is brought into contact with the bottom of the well or the suspected fish's location by controlling the drill string's descent speed. The contact status is assessed by observing changes in the top drive's suspended weight. Then, a rotational motion is used to attempt to engage the fish. During tripping, fluctuations in suspended weight and pump pressure are used to further determine the capture status. This method securely connects the retrieval tool to the fish and is applicable to fish of various masses. However, it lacks direct perception of the fish's top, making misjudgments (such as tool jamming or misalignment with the fish's top) prone to occur. Especially in deviated or horizontal wells where the fish is close to the well wall, problems often arise where the retrieval tool "rides" the fish, "grazes" the edge, or repeatedly passes over the fish's top without being able to engage. This necessitates multiple tripping operations to adjust the tool or plan, resulting in low operational efficiency. Although strong magnetic suction blind fishing can directly attract fish with magnetic force and eliminate the above problems, it is limited by magnetic force. For large fish at the bottom of the well, it is easy to "attract but not hold firmly" or fall off during the drilling process. Therefore, it is only suitable for small fish.

[0005] Secondly, detection methods such as lead mold imprints and acoustic imaging are used for "look first, then retrieve," but their detection effect is easily affected by factors such as well temperature, well fluid density, gas intrusion, and control consistency, resulting in distorted imprints and images. Moreover, the interpretation results are highly subjective and cannot achieve accurate acquisition of information about the fish head.

[0006] In summary, existing fish retrieval technologies generally suffer from problems such as insufficient accuracy in locating the top of the fish, uncontrollable centering and capture processes, and difficulty in accurately confirming the capture status. These defects are even more pronounced in complex well conditions such as deviated wells and deep wells, which seriously restrict the efficiency and safety of retrieval operations. A new technical solution is urgently needed to address these issues. Summary of the Invention

[0007] To address at least one of the aforementioned problems, the present invention provides a retrieval device that can quickly, accurately, and stably provide clues to the suspicious location of the fish's top / break, thereby improving the success rate of a single retrieval and effectively reducing non-productive time.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A salvage device includes a salvage tool, a magnetic detector, and a guide shoe connected in sequence. The guide shoe is made of a non-magnetic material, and the magnetic detector includes:

[0010] A tubular shell;

[0011] An inner cylinder is coaxially fitted with the outer shell, and the inner cylinder and the outer shell are sealed together to form a sealed cavity;

[0012] A perforated ball head located inside the sealed cavity and coaxially sleeved on the outer wall of the inner cylinder;

[0013] The ball socket is fitted onto the outer wall of the perforated ball head and combined with it to form a ball hinge structure. The inner wall of the ball socket slides with the keyway of the perforated ball head, so that the ball socket can only rotate along the longitudinal section of the ball socket.

[0014] Heilbeck array permanent magnets fixedly connected to the ball socket;

[0015] Multiple force sensors are arranged in a ring array on the inner cylinder, and each force sensor is fixedly connected to the Heilbeck array permanent magnet through an elastic element.

[0016] The display and power supply device is electrically connected to the force sensor and is used to power and display the force magnitude applied to the force sensor.

[0017] In one specific embodiment of the present invention, the perforated ball head is slidably connected to the inner cylinder, so that the perforated ball head can slide along the axial direction of the inner cylinder.

[0018] In one specific embodiment of the present invention, the end of the Hellbeck array permanent magnet facing the guide shoe is provided with an annular pole shoe, which is used to guide the magnetic field generated by the Hellbeck array permanent magnet, so that the magnetic field distribution is more uniform.

[0019] As a specific embodiment of the present invention, it also includes a magnetic yoke, which includes a magnetic yoke body and a transition magnetic circuit section located between the Hellbeck array permanent magnet and the pole shoe. The transition magnetic circuit section is made of soft magnetic material and is used to continuously introduce magnetic flux into the pole shoe. The magnetic yoke body is located on the end face of the Hellbeck array permanent magnet away from the pole shoe.

[0020] In one specific embodiment of the present invention, the sealed cavity is provided with an inverted funnel-shaped guide section at the end opposite to the guide shoe, which facilitates guiding the fish into the inner cylinder.

[0021] In one specific embodiment of the present invention, the sealing body is filled with an insulating fluid, and the end of the sealing cavity facing the salvage tool is a piston ring, which is located between the inner cylinder and the outer shell and is slidably connected to both.

[0022] As a specific embodiment of the present invention, the piston ring is provided with limiting members at both the upper and lower parts, which are fixedly connected to the inner cylinder or the shell, to limit the piston ring to slide between the inner cylinder and the shell.

[0023] A method for retrieving fish that have fallen into a well using the aforementioned retrieval equipment includes the following steps:

[0024] S1. Place the display and power supply equipment on the ground and establish an electrical connection with the force sensor of the magnetic detector; connect the retrieval tool, magnetic detector and guide shoe to the lower end of the tubing string and lower them into the well along with the tubing string;

[0025] S2. During the lowering of the tubing, the overall force change of each force sensor is monitored in real time through the display and power supply equipment. When the force of each force sensor increases synchronously, it is determined that the magnetic detector has entered the magnetic field range of the fish, thus completing the preliminary confirmation of the fish's location.

[0026] S3. Continue lowering the tube column. During the lowering process, obtain the force distribution of the Heilbeck array permanent magnet based on the force data of each force sensor, and determine the tilt direction of the top of the falling fish and its relative position with the guide shoe.

[0027] S4. Based on the force distribution of the Hellbeck array permanent magnet, the deflection direction of the top of the fish and its relative position with the guide shoe, the ground operator adjusts the azimuth angle of the column or performs a small lifting and lowering to gradually align the axis of the guide shoe with the direction of the top of the fish, thereby completing the centering correction before capture.

[0028] S5. After completing the attitude correction, continue to lower the tubing to guide the fish into the retrieval tool; then, use the retrieval tool to mechanically capture the fish.

[0029] S6. After capturing the fish, pull the drill string out and bring the fish and the retrieval equipment to the wellhead to complete the retrieval operation.

[0030] In one specific embodiment of the present invention, the lowering speed of the tubing in step S3 is greater than that in step S2, so as to reduce the overall salvage time.

[0031] As a specific embodiment of the present invention, it also includes simulating the force conditions of each force sensor when the Hellbeck array permanent magnet and the fish are at different distances in a simulated well environment on the ground, so that in step S2, the distance between the fish and the guide shoe can be estimated based on the force conditions of each force sensor, and the lowering speed can be controlled.

[0032] As a specific embodiment of the present invention, it also includes simulating the force distribution of the Hellbeck array permanent magnet corresponding to different fish falling postures in a simulated well environment on the ground, so that in step S3, the posture of the fish falling and the relative position relationship between the guide shoe and the top of the fish can be deduced based on the force distribution of the Hellbeck array permanent magnet.

[0033] Compared with existing technologies, it has the following advantages:

[0034] (1) It can determine the attitude of the fish top: The present invention monitors the force distribution of the Heilbeck array permanent magnet in real time through the force sensors in the magnetic detector, and can obtain the spatial position and tilt direction information of the fish top before retrieval, thus avoiding the problem of relying entirely on experience judgment in the traditional blind retrieval process.

[0035] (2) It can significantly improve the centering accuracy and the success rate of one-time retrieval: By correcting the attitude of the retrieval tool before capture, the retrieval tool can be effectively aligned with the top of the fish, reducing failure conditions such as "riding the fish" and "grabbing the edge", and reducing the number of times the drill is repeatedly pulled up and down.

[0036] (3) It can effectively shorten the operation cycle and reduce non-productive time: Compared with the traditional blind fishing method of multiple trial explorations, the present invention can complete the positioning, correction and capture in one well run, significantly reducing the ineffective operation time and improving the operation efficiency. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of a specific embodiment of the salvage equipment of the present invention;

[0038] Figure 2 for Figure 1 A schematic diagram of the magnetic detector in the salvage equipment shown.

[0039] Figure 3 for Figure 2 The diagram shows the state of the magnetic detector when a fish is attracted to it.

[0040] Figure 4 for Figure 2Top view of the Hellbeck array permanent magnets in the magnetic detector shown;

[0041] Figure 5 for Figure 4 The diagram shows the magnetic field distribution of the Heilbeck array permanent magnets.

[0042] In the diagram, 100-salvage tool; 200-magnetic detector; 300-guide shoe; 210-shell; 220-inner cylinder; 230-perforated ball head; 240-ball socket; 250-Haelbeck array permanent magnet; 260-force sensor; 270-elastic element; 280-sealed cavity; 290-pole shoe; 201-magnetic yoke body; 202-transition magnetic circuit section; 281-piston ring; 282-limiting component. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0044] Please refer to Figures 1 to 5 This illustrates the structure of a specific embodiment of the salvage device of the present invention. For example... Figure 1 As shown, the retrieval device of the present invention includes a retrieval tool 100, a magnetic detector 200, and a guide shoe 300 connected sequentially from top to bottom. The retrieval tool 100 is a retrieval tube used to capture fallen fish, and the guide shoe 300 is used to guide the fallen fish into the retrieval device. Both of these parts are conventional components of existing retrieval devices. For example, one can refer to the fully reversible extended retractable slip retrieval tube disclosed in CN202323356091 and the related settings in a slip retrieval tube disclosed in CN202420053682, which will not be detailed here. The key feature of this invention is the inclusion of the magnetic detector 200, used to detect the location of the fallen fish, especially the posture of the fish's head, thus saving retrieval time. The magnetic detector 200 will be described in detail below with reference to the accompanying drawings.

[0045] Please refer to Figures 2-5The magnetic detector 200 in this embodiment mainly comprises several core components: a housing 210, an inner cylinder 220, a perforated ball head 230, a ball socket 240, a Helbeck array permanent magnet 250, multiple force sensors 260, an elastic element 270, and a display and power supply device. The housing 210 is tubular. The inner cylinder 220 and housing 210 are assembled coaxially and sealed together. This sealed assembly structure forms a closed cavity 280 between the housing 210 and the inner cylinder 220, which accommodates other components and prevents drilling fluid from damaging them. The perforated ball head 230 is located within the sealed cavity 280 and is also coaxially mounted on the outer wall of the inner cylinder 220. The ball socket 240 is fitted onto the outer wall of the perforated ball head 230, and the two together form a ball socket. The hinge structure prevents the ball socket 240 and the perforated ball head 230 from separating, but allows them to rotate relative to each other. Furthermore, the inner wall of the ball socket 240 and the outer wall of the perforated ball head 230 are connected by a keyway sliding fit. This sliding fit restricts the movement direction of the ball socket 240, allowing it to rotate only along its longitudinal section (parallel to the centerline of the inner cylinder 220). The Helbeck array permanent magnet 250 is fixedly connected to the ball socket 240, enabling synchronous movement. Multiple force sensors 260 are uniformly fixed in a ring array. Fixed on the inner cylinder 220, each force sensor 260 is equipped with a corresponding elastic element 270. The force sensors 260 are fixedly connected to the Heilbeck array permanent magnet 250 through their respective elastic elements 270. The elastic elements 270 can buffer and transmit force between the two, so that during the lowering process, the longitudinal section of the ball socket 240 is aligned / parallel with the longitudinal section of the ball head, and the force on each force sensor is small and basically similar. When the top of the falling fish is sensed, the various parts of the Heilbeck array permanent magnet 250 are aligned with the top of the falling fish. The positional differences of the parts cause variations in force, resulting in the rotation of the ball socket 240 around the ball head. The display and power supply device is electrically connected to the force sensor 260. On the one hand, this provides power support for the operation of the force sensor 260; on the other hand, the relevant signals detected by the force sensor 260 can also be transmitted to the display and power supply device via electrical connection, where the data is displayed. The attitude of the top of the fish is then determined by the relative magnitude of the data from each force sensor (i.e., the force distribution on the Hellbeck array permanent magnet 250). Figure 3 As shown, when the top of the fish tilts to the left, the magnetic attraction between the Hellbeck array permanent magnet 250 and the fish varies at different points, causing the Hellbeck array permanent magnet to deflect. The situation of the top of the fish can be determined by the force state of each force sensor on the ground.

[0046] In some embodiments, the perforated ball head 230 is slidably connected to the inner cylinder 220, allowing the perforated ball head 230 to slide along the axial direction of the inner cylinder 220. When the retrieval equipment moves in the well, the magnetic force on the Heilbeck array permanent magnet 250 increases as the distance between the retrieval equipment and the fallen fish decreases, thereby driving the retrieval ball head to move, which increases the overall force on all force sensors 260. Thus, the distance between the retrieval equipment and the fallen fish can be initially estimated by the overall force change of the force sensors 260.

[0047] In some embodiments, the end of the Hellbeck array permanent magnet 250 facing the guide shoe 300 is provided with a pole shoe, and the end of the pole shoe facing the guide shoe 300 is a flared mouth, which is used to guide the magnetic field generated by the Hellbeck array permanent magnet, so that the magnetic field distribution is more uniform.

[0048] In some embodiments, the sealed cavity 280 is provided with an inverted funnel-shaped guide section at one end opposite the guide shoe 300, which facilitates guiding the fish into the inner cylinder 220.

[0049] In some embodiments, the sealed cavity 280 is filled with an insulating fluid (such as silicone oil or transformer oil). The end of the sealed cavity 280 facing the retrieval tool 100 is a piston ring 281, which is located between the inner cylinder 220 and the housing 210 and is slidably connected to both. To prevent the piston ring 281 from detaching from the inner cylinder 220, limiting members 282 are provided above and below the piston ring 281, which are fixedly connected to the inner cylinder 220 or the housing 210, thereby limiting the piston ring 281 from sliding between the inner cylinder 220 and the housing 210. The specific structure of the limiting member 282 can be selected as needed, for example... Figure 2 As shown, the limiting member 282 is annular and has a through hole to facilitate fluid to pass through the limiting member 282 and contact the piston ring 281.

[0050] In some embodiments, the magnetic detector 200 further includes a magnetic yoke, which comprises a yoke body 201 and a transition magnetic circuit section 202 (also referred to as a transition yoke or magnetically conductive transition element), both made of the same or similar materials. The transition magnetic circuit section 202 is disposed between the Halebeck array permanent magnet 250 and the pole shoe 290, and is made of soft magnetic material. It forms a continuous low-resistivity magnetically conductive channel between the output end of the Halebeck array permanent magnet 250 and the inlet end of the pole shoe 290. The cross-section of the transition magnetic circuit section 202 has a gradient structure to ensure a smooth transition in magnetic flux density, reduce local saturation and magnetic flux leakage, and improve the magnetic flux concentration effect and effective operating distance at the working end of the pole shoe 290. Simultaneously, the transition magnetic circuit section 202, the housing 210, and the pole shoe 290 form a rigid connection, serving as one of the transmission paths for the magnetic attraction reaction force. This stably transmits the reaction force generated by the magnetic attraction effect of the Halebeck array permanent magnet to the housing's force-bearing structure and the sensor, thereby improving the stability and repeatability of the circumferential differential signal. The magnetic yoke body 201 is located on the end face of the Hellbeck array permanent magnet 250 away from the guide shoe 300.

[0051] In some embodiments, the Heilbeck array permanent magnet 250, force sensor 260, pole shoe 290, and yoke are encapsulated in a housing (such as a high-temperature resistant plastic housing). In other embodiments, these components may also be fixed together in other ways.

[0052] A method for retrieving fish that have fallen into a well using the aforementioned retrieval equipment includes the following steps:

[0053] S1. Place the display and power supply equipment of the retrieval equipment on the ground and establish an electrical connection with the force sensor in the magnetic detector. Connect the retrieval tube, magnetic detector, and guide shoe to the lower end of the tubing string in sequence to form a complete retrieval tool string. Simulate the force conditions of each force sensor when the fish is at different distances from the Hellbeck array permanent magnet in a simulated wellbore environment on the ground. In step S2, the distance between the fish and the guide shoe can be roughly estimated based on the force conditions of each force sensor to control the lowering speed. Simulate the force distribution of the Hellbeck array permanent magnet corresponding to different fish postures in a simulated wellbore environment on the ground. In step S3, the posture of the fish and the relative positional relationship between the two (guide shoe and fish top) can be deduced based on the force distribution of the Hellbeck array permanent magnet. After the simulation is completed, the retrieval tool string is lowered into the well along with the tubing string.

[0054] S2. During the lowering of the tubing string, control the lowering speed so that the magnetic detector gradually approaches the location where the fish fell in the well. Monitor the overall force change of each force sensor in real time through the display and power supply equipment. When the output signal of each force sensor increases synchronously, it is determined that the magnetic detector has entered the magnetic effect range of the fish, thus completing the preliminary confirmation of the location of the fish.

[0055] S3. Continue to slowly lower the tube column (lower than the lowering speed in step S2). At this time, the Hellbeck array permanent magnet has a magnetic attraction effect on the top or near-top area of ​​the fish. Due to the different postures of the fish top and its spatial positional relationship with the Hellbeck array permanent magnet, the magnetic attraction force on different parts of the Hellbeck array permanent magnet is different, which will cause different force sensors to produce different force outputs. Therefore, during the magnetic attraction process, the force data of each force sensor is collected in real time, and the deflection direction of the fish top and its relative position with the guide shoe are determined based on the relative force difference between different force sensors (i.e., the force distribution of the Hellbeck array permanent magnet).

[0056] S4. Based on the force distribution of the Hellbeck array permanent magnet, the deflection direction of the top of the fish and its relative position with the guide shoe, the ground operator adjusts the azimuth angle of the column or performs a small lifting and lowering to gradually align the axis of the guide shoe with the direction of the top of the fish, thereby completing the centering correction before capture.

[0057] S5. After completing the attitude correction, continue to lower the tubing to guide the fish into the retrieval tube. Then, the fish is mechanically captured through the retrieval tube.

[0058] S6. After capturing the fish, pull the drill string out and bring the fish and the retrieval equipment to the wellhead to complete the retrieval operation.

[0059] Compared to existing blind fishing methods, this invention transforms the operational process from "post-judgment" to "pre-judgment and correction." Traditional blind fishing attempts to capture fish directly without obtaining information about the fish's top posture; its success can only be inferred from changes in the suspended weight and pump pressure after drilling. In contrast, this invention obtains the spatial position information of the fish's top using a magnetic detector before capture and adjusts its posture accordingly, thereby achieving targeted and purposeful fishing operations and significantly reducing the uncertainty caused by blind attempts.

[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes, modifications, substitutions and variations made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A salvage device, characterized in that, The system includes a salvage tool, a magnetic detector, and a guide shoe connected in sequence. The guide shoe is made of a non-magnetic material, and the magnetic detector includes: A tubular shell; An inner cylinder is coaxially sleeved with the shell, and the inner cylinder is sealed to the shell to form a sealed cavity; A perforated ball head located within the sealed cavity and coaxially sleeved on the outer wall of the inner cylinder; A ball socket is fitted onto the outer wall of the perforated ball head and combined with it to form a ball hinge structure. The inner wall of the ball socket slides with the keyway of the perforated ball head, so that the ball socket can only rotate along the longitudinal section of the ball socket. The Heilbeck array permanent magnet is fixedly connected to the ball-and-socket joint; Multiple force sensors are arranged in a ring array on the inner cylinder, and each force sensor is fixedly connected to the Heilbeck array permanent magnet through an elastic element; The display and power supply device is electrically connected to the force sensor and is used to power and display the force magnitude of the force sensor.

2. The salvage equipment according to claim 1, characterized in that, The Helbeck array permanent magnet has a ring-shaped pole shoe at one end facing the guide shoe.

3. The salvage equipment according to claim 2, characterized in that, It also includes a magnetic yoke, which includes a yoke body and a transition magnetic circuit section located between the Helbeck array permanent magnet and the pole shoe. The transition magnetic circuit section is made of soft magnetic material and is used to continuously introduce magnetic flux into the pole shoe. The magnetic yoke body is located on the end face of the Helbeck array permanent magnet away from the pole shoe.

4. The salvage equipment according to claim 1, characterized in that, The sealed cavity has an inverted funnel-shaped guide section at one end facing the shoe.

5. The salvage equipment according to claim 1, characterized in that, The sealed cavity is filled with insulating fluid. The end of the sealed cavity facing the salvage tool is a piston ring, which is located between the inner cylinder and the outer shell and is slidably connected to both.

6. The salvage equipment according to claim 5, characterized in that, The piston ring is provided with limiting members at both the upper and lower parts, which are fixedly connected to the inner cylinder or the housing, to limit the piston ring from sliding between the inner cylinder and the housing.

7. A salvage method, characterized in that, Retrieving fish from a well using any one of the retrieval devices described in claims 1-6 includes the following steps: S1. Place the display and power supply equipment on the ground and establish an electrical connection with the force sensor of the magnetic detector; connect the retrieval tool, magnetic detector and guide shoe to the lower end of the tubing string and lower them into the well along with the tubing string; S2. During the lowering of the tubing, the overall force change of each force sensor is monitored in real time through the display and power supply equipment. When the force of each force sensor increases synchronously, it is determined that the magnetic detector has entered the magnetic field range of the fish, thus completing the preliminary confirmation of the fish's location. S3. Continue lowering the tube column. During the lowering process, obtain the force distribution of the Heilbeck array permanent magnet based on the force data of each force sensor, and determine the tilt direction of the top of the falling fish and its relative position with the guide shoe. S4. Based on the force distribution of the Hellbeck array permanent magnet, the deflection direction of the top of the fish and its relative position with the guide shoe, the ground operator adjusts the azimuth angle of the column or performs a small lifting and lowering to gradually align the axis of the guide shoe with the direction of the top of the fish, thereby completing the centering correction before capture. S5. After completing the attitude correction, continue to lower the tubing to guide the fish into the retrieval tool; then, use the retrieval tool to mechanically capture the fish. S6. After capturing the fish, pull the drill string out and bring the fish and the retrieval equipment to the wellhead to complete the retrieval operation.

8. The salvage method according to claim 7, characterized in that, It also includes simulating the force conditions of each force sensor when the Hellbeck array permanent magnet and the fish are at different distances in a simulated well environment on the ground, so that in step S2, the distance between the fish and the guide shoe can be estimated based on the force conditions of each force sensor, and the descent speed can be controlled.

9. The salvage method according to claim 7, characterized in that, It also includes simulating the force distribution of the Hellbeck array permanent magnets corresponding to different fish falling in a simulated well environment on the ground, so that in step S3, the posture of the falling fish and the relative position relationship between the guide shoe and the top of the fish can be deduced based on the force distribution of the Hellbeck array permanent magnets.

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