A tubing fishing device

Abstract

The utility model relates to the fishing tool used for fishing the object in the well from the outside, especially relates to a oil pipe fishing device. The oil pipe fishing device includes outer anchoring cylinder and inner anchoring sleeve, is equipped with the sleeve anchor section at the lower end of outer anchoring cylinder, is provided with the inner engagement tooth on the inner wall of sleeve anchor section, and the inner anchoring sleeve is fixed in the outer anchoring cylinder, is provided with the expansion anchor claw of insertable drop well oil pipe on the inner anchoring sleeve, is equipped with the outer engagement tooth on the back of expansion anchor claw, is installed with the taper head hollow piston in the inner anchoring sleeve, and the expansion anchor claw can be driven to expand to anchor the inner wall of drop well oil pipe through the ball pressure of throwing ball to the taper head hollow piston. The oil pipe fishing device of the utility model sets up the inner anchoring sleeve, and sets up expansion anchor claw on the inner anchoring sleeve, solves the problem of the insufficient gripping force, the engagement easy to slip off and the final fishing failure of the existing fishing tool due to the dependence on the mother cone thread engagement when fishing the oil pipe with the seriously corroded outer wall or the irregular form damage, and the problem of fishing failure is solved.

Description

Technical Field

[0001] This utility model relates to a salvage tool used for retrieving objects from a well from the outside, and in particular to an oil pipe salvage device. Background Technology

[0002] In oil and water well production, the loss of downhole tubing due to corrosion and uneven wear is a common operational challenge. Current mainstream retrieval tools (such as female cones, male cones, and sliding spears) are designed for intact, regularly shaped tubing objects. However, for the numerous cases of severely damaged or fractured tubing caused by corrosion and uneven wear in actual operations, existing tools often fail to achieve effective engagement and gripping, leading to retrieval failures. Faced with such problems, work teams are usually forced to abandon retrieval efforts and resort to milling operations. This approach not only significantly prolongs the well workover period and greatly increases operational costs, but the milling process also poses a direct risk of damage to the casing, making it time-consuming, costly, and fraught with hidden dangers.

[0003] To address the aforementioned issues, patent specification CN2906039Y provides a downhole damaged pipe retrieval tool. This tool comprises core components such as an upper connector, a female cone, a guide shoe, a piston, and an inner cone. The upper and lower ends of the female cone are connected to the upper connector and the guide shoe, respectively. The piston is located at the upper part of the internal cavity, and a movable inner cone is installed at the lower part. After the guide shoe guides the broken top (the upper surface of the fallen object), a steel ball is dropped from the wellhead to sit on the piston and pressurize it, pushing the inner cone downwards. The cone's surface acts like "wire cutters," squeezing and locking the irregularly shaped damaged pipe string. This eliminates the need for pre-milling and trimming the top, enabling direct retrieval, effectively simplifying the operation and improving retrieval efficiency.

[0004] Although the retrieval tools disclosed in the aforementioned patents enable the direct retrieval of damaged pipes without the need for trimming the top of the pipe, their reliability and adaptability in practical applications still have certain limitations. First, their gripping mechanism relies entirely on the mechanical engagement between the inner wall thread of the female cone and the outer surface of the object. When dealing with objects whose walls have thinned and strength significantly reduced due to long-term corrosion, the female cone thread struggles to effectively cut into the fragile pipe body. This not only fails to create sufficient embedment depth but also easily causes shear damage to the remaining pipe wall during the retrieval process, leading to engagement failure. Second, while they rely on hydraulic pressure to push the inner cone downwards to compress the object, the inner cone itself lacks a mechanical locking function. During tripping out of the well, complex downhole vibrations, the elastic expansion and contraction of the tubing string, and potential resistance fluctuations can easily cause the inner cone to retract, disrupting the established compression state and ultimately leading to a loosening of the grip or even the object falling off, resulting in retrieval failure. Utility Model Content

[0005] The purpose of this utility model is to provide an oil pipe retrieval device to solve the problems of insufficient gripping force, easy slippage of the gripping mesh, and eventual retrieval failure when retrieving oil pipes with severe outer wall corrosion or irregular shape damage due to the reliance on the female tapered thread engagement of existing retrieval tools.

[0006] To solve the above problems, the oil pipe retrieval device of this utility model adopts the following technical solution: An oil pipe retrieval device includes an outer anchoring cylinder and an inner anchoring sleeve. The lower end of the outer anchoring cylinder is provided with a sleeve anchoring section, and the inner wall of the sleeve anchoring section is provided with internal interlocking teeth. The inner anchoring sleeve is fixed in the outer anchoring cylinder. An expansion anchor claw that can be inserted into the downhole oil pipe is provided on the inner anchoring sleeve. The back of the expansion anchor claw is provided with external interlocking teeth. A conical hollow piston is installed in the inner anchoring sleeve. By throwing a ball into the conical hollow piston to pressurize it, the expansion anchor claw can be driven to expand outward to anchor the inner wall of the downhole oil pipe.

[0007] Furthermore, the lower end of the expanding anchor claw converges towards the center in the initial state to form an inverted cone-shaped structure.

[0008] Furthermore, the upper end of the hollow cone piston is provided with a position locking section, and a one-way locking mechanism that only allows the hollow cone piston to move downward is provided between the position locking section and the outer anchoring cylinder.

[0009] Furthermore, the one-way locking mechanism is a ratchet mechanism or a one-way clamp mechanism.

[0010] Furthermore, a shear pin is provided between the position locking section and the outer anchoring cylinder to lock the initial position of the cone-shaped hollow piston. When in the initial position, the cone-shaped hollow piston is locked by the shear pin and cannot move downward, thus not acting on the expanding anchor claw.

[0011] Furthermore, the outer anchoring cylinder comprises a separate upper section and a lower section, and the inner anchoring sleeve is provided with an adapter, with the upper section and the lower section respectively threadedly connected to the adapter.

[0012] Furthermore, the cross-sections of both the internal and external biting teeth are wedge-shaped.

[0013] Furthermore, the internal engagement teeth are helical teeth, formed by machining threads on the inner wall of the outer anchoring cylinder.

[0014] Furthermore, the inner anchor sleeve has multiple expanded anchor claws, which are evenly distributed around the center line of the inner anchor sleeve.

[0015] Furthermore, a guide shoe is provided at the lower end of the outer anchoring cylinder.

[0016] The beneficial effects of the technical solution of the tubing retrieval device of this utility model: The tubing retrieval device of this utility model is an improved invention. Specifically, the tubing retrieval device of this utility model sets an inner anchoring sleeve, and sets an expanding anchor claw on the inner anchoring sleeve. An external biting tooth is set on the back of the expanding anchor claw, and a conical hollow piston is installed in the inner anchoring sleeve. By throwing a ball into the conical hollow piston and pressing it, the expanding anchor claw can be driven to expand outward to anchor the inner wall of the fallen tubing. Thus, in conjunction with the outer anchoring cylinder, the tubing wall of the fallen tubing is clamped (tightened). This solves the problem that existing retrieval tools rely on the biting of the female conical thread, which leads to insufficient gripping force, easy slippage of the biting, and ultimately retrieval failure when retrieving tubing with severe outer wall corrosion or irregular shape damage. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of one embodiment of the oil pipe retrieval device of this utility model; Figure 2 yes Figure 1 Diagram showing the operational status of the tubing retrieval device (clamping the tubing that has been lowered into the well). Figure 3 yes Figure 1 A schematic diagram of the structure of the conical hollow piston; Figure 4 yes Figure 1 A schematic diagram of the inner anchoring sleeve in the middle; Figure 5 yes Figure 1 A schematic diagram of the lower section of the outer anchoring cylinder.

[0018] In the diagram: 1. Outer anchoring sleeve; 101. Inner engagement tooth; 102. Upper connector; 103. Guide shoe; 2. Inner anchoring sleeve; 201. Expanding anchor claw; 202. Outer engagement tooth; 203. Adapter connector; 3. Well tubing; 4. Conical hollow piston; 401. Flow channel; 402. Valve seat; 5. Sealing ring; 6. Valve ball; 7. Shear pin; 801. Straight rack; 802. Elastic pawl. Detailed Implementation

[0019] The features and performance of this utility model will be further described in detail below with reference to specific embodiments.

[0020] During the production process of oil and water wells, the downhole tubing is subjected to the dual effects of corrosion from the fluid inside the well and mechanical wear on the well wall for a long time. This causes the tubing wall to become thinner and the mechanical strength to decrease, eventually leading to tubing rupture or thread stripping, resulting in tubing falling into the well.

[0021] Currently, retrieval tools rely on mechanical engagement with the outer wall of the fallen tubing to achieve retrieval. However, when the engagement point of the tool happens to be located in a severely corroded or damaged area of ​​the tubing, the fallen tubing may not provide sufficient structural strength to support an effective engagement. This not only prevents the tool threads from "biting" into the tubing wall, resulting in insufficient gripping force, but may also cause the engagement point to slip during the retrieval process, leading to the failure of the entire retrieval operation. This uncertainty not only prolongs the well workover cycle but also causes a sharp increase in labor and material costs due to repeated attempts and ineffective operations.

[0022] This invention is based on the concept of "clamping (tightening) the pipe wall," which simultaneously engages the inner and outer walls of the pipe during retrieval, thereby effectively reducing the probability of pipe retrieval failure or slippage. Based on the above invention concept, this invention proposes a technical solution for a pipe retrieval device.

[0023] The specific implementation method of the oil pipe retrieval device of this utility model will be described below.

[0024] like Figures 1-5 As shown, the tubing retrieval device of this utility model includes an outer anchoring cylinder 1 and an inner anchoring sleeve 2. In use, the tubing retrieval device can be sent from the wellhead to the upper end of the downhole tubing 3 using a retrieval string. The string is then lowered to place the outer anchoring cylinder 1 over the outside of the downhole tubing 3, while the inner anchoring sleeve 2 is inserted into the inside of the downhole tubing 3. The outer anchoring cylinder 1 anchors the outer wall of the downhole tubing 3, and the inner anchoring sleeve 2 anchors the inner wall of the downhole tubing 3. This achieves bidirectional, double anchoring of the inner and outer walls of the downhole tubing 3, improving the success rate of retrieving the downhole tubing 3 and the reliability of the retrieved tubing.

[0025] The structure of the outer anchoring cylinder 1 is as follows Figure 1 , Figure 2 , Figure 5 As shown, the device is cylindrical in shape, with a sleeve anchor section at the bottom for fitting over the fall-off tubing 3 and anchoring it. To achieve reliable anchoring of the fall-off tubing 3, internal engagement teeth 101 are provided on the inner wall of the sleeve anchor section. These internal engagement teeth 101 are formed by internal threads within the sleeve anchor section, and their cross-section is wedge-shaped to facilitate barbed engagement. In other embodiments, as another typical structure, the internal engagement teeth 101 can also be annular, coaxial with the sleeve anchor section. Besides the wedge shape described above, the cross-section of the internal engagement teeth 101 can also be equilateral triangular, etc. Furthermore, Figure 5 In the illustrated embodiment, the internal engagement teeth 101 are spiral-shaped. In other embodiments, the internal engagement teeth 101 can also be arc-shaped teeth or discretely distributed multi-tooth structures. This should be understood by those skilled in the art, and will not be elaborated here.

[0026] An upper connector 102 is provided at the upper end of the outer anchoring cylinder 1. The upper connector 102 is used to connect the retrieval pipe string used for retrieval. The upper connector 102 is a threaded connector, and its structure is existing technology, so it will not be described in detail here.

[0027] A guide shoe 103 is provided at the lower end of the outer anchoring cylinder 1. The guide shoe 103 is used to guide the upper end of the downhole tubing 3 into the outer anchoring cylinder 1. Since the installation of a guide shoe on the outer anchoring cylinder 1 is common knowledge in this field, the structure and installation method of the guide shoe 103 will not be described in detail here.

[0028] The inner anchoring sleeve 2 is fixedly installed in the outer anchoring cylinder 1. An expanded anchor claw 201 is provided at its lower end corresponding to the position of the inner interlocking teeth. An outer interlocking tooth 202 is provided on the back of the expanded anchor claw 201. The shape and arrangement of the outer interlocking tooth 202 can refer to the inner interlocking tooth 101 described above, and will not be elaborated further here. The outer interlocking tooth 202 can engage with the inner wall surface of the downhole tubing 3, thereby fixing the downhole tubing 3. When the inner interlocking tooth 101 and the outer interlocking tooth 202 act simultaneously on the wall of the downhole tubing 3, they will form a clamp-like structure, firmly clamping the wall of the downhole tubing 3, thereby achieving reliable clamping of the downhole tubing 3.

[0029] To facilitate insertion into the downhole tubing 3, the front ends of each expanding anchor claw 201 at the lower end of the inner anchoring sleeve 2 are tilted towards the center. This creates a conical structure at the lower end of the inner anchoring sleeve 2 when the expanding anchor claws 201 are in the retracted state. This allows the expanding anchor claws 201 to smoothly enter the downhole tubing 3 in the initial state. When they are engaged and fixed with the downhole tubing 3, appropriate components are needed to expand them radially. The expansion of the expanding anchor claws 201 is achieved through a conical hollow piston 4, which is installed in the inner anchoring sleeve 2. The sealing ring 5 on the piston 4 serves as the piston ring, and a vertically penetrating flow channel 401 is formed in the hollow of the conical hollow piston 4 to flush the top of the fish before retrieval.

[0030] In the initial state, the conical hollow piston 4 is in a high position, and its conical head does not exert force on the expanding anchor claws 201, which remain in a retracted state. When it is necessary to retrieve the downhole tubing 3, the conical hollow piston 4 is pushed downward, and its conical head immediately embeds into the space enclosed by the expanding anchor claws 201. Under the action of the conical surface, all the expanding anchor claws 201 are forced to expand radially outward synchronously, so that the outer biting teeth 202 on their outer surface work together with the inner biting teeth 101 on the inner wall of the outer anchoring cylinder 1 to bite and clamp the tubing wall of the downhole tubing 3 from both the inside and outside, thereby achieving reliable retrieval.

[0031] The downward movement of the conical hollow piston 4 is achieved by a combination of ground ball dropping and pump pressure operation. Specifically, a valve seat 402 is provided at the upper end of the conical hollow piston 4. During operation, a valve ball 6 of a specific size is dropped from the wellhead. The valve ball 6 moves downward with the circulating medium until it sits on the valve seat 402, thereby completely sealing the flow channel in its center.

[0032] Once the flow channel 401 is sealed, continued pump pressure from the surface causes the workover fluid pressure to rapidly build up above the sealed piston chamber. With the central flow channel 401 blocked, the hydraulic force is concentrated on pushing the conical hollow piston 4 downwards against resistance. This process converts the hydraulic energy supplied from the surface into the mechanical displacement of the conical hollow piston 4, which in turn drives the conical head at its front end to compress and expand the anchor claw 201, ultimately completing the anchoring action.

[0033] To ensure the absolute reliability of the retrieval tool under complex downhole conditions, the conical hollow piston 4 must have a dual locking function: First, during the tool lowering process, an initial position locking mechanism is required to resist vibration and impact, preventing premature piston displacement that could cause the expansion anchor claw 201 to open accidentally, thus avoiding tool jamming or damage; Second, after the hydraulically driven conical hollow piston 4 is in place and anchored, a locking position locking mechanism must be immediately used to mechanically lock it, overcoming the risk of backlash caused by the elastic expansion and contraction of the tubing and vibration during subsequent tripping, preventing secondary detachment of the object due to loosening of the clamping force, and ultimately ensuring a high success rate for retrieval in one attempt.

[0034] To meet the above requirements, a position locking section is provided at the upper end of the conical hollow piston 4. This position locking section engages with the outer anchoring cylinder 1 via a shear pin 7 to lock its initial position. Furthermore, a one-way locking structure is provided between the position locking section and the outer anchoring cylinder 1 to restrict the conical hollow piston to move only downwards. Figures 1-5 In the embodiment shown, the one-way locking structure specifically adopts a ratchet mechanism, including a straight rack 801 formed on the outer wall of the position locking section and an elastic pawl 802 disposed on the inner wall of the outer anchoring cylinder. The elastic pawl 802 engages with the straight rack 801, allowing the piston to move downward and preventing it from retracting.

[0035] Although the one-way locking structure in the above embodiments uses a ratchet mechanism, those skilled in the art should understand that in other embodiments, the one-way locking mechanism can also use a one-way clamp mechanism. The one-way clamp mechanism includes an annular groove provided in the position locking section and an elastic clamp provided in the inner wall of the outer anchoring cylinder. When the conical hollow piston moves to the working position, the elastic clamp is engaged in the annular groove under the action of radial elastic force to achieve one-way locking. As a further optimization, the elastic clamp can be set as a C-shaped open elastic retaining ring, and guide slopes are designed at both ends of the opening.

[0036] To simplify the assembly of the inner anchoring sleeve, the conical hollow piston, and the outer anchoring cylinder, in Figure 1 , Figure 4 In the embodiment shown, the upper end of the inner anchoring sleeve 2 is integrally formed with an adapter 203, and the outer anchoring cylinder 1 is divided into upper and lower sections. The upper end of the adapter 203 is threadedly connected to the upper section of the outer anchoring cylinder 1 through an internal thread, and the lower end of the adapter 203 is threadedly connected to the lower section of the outer anchoring cylinder through an internal thread.

[0037] In implementation, the upper connector 102 is connected to the bottom of the retrieval string and lowered into the well along with the retrieval string. When the retrieval string is lowered to the position of the downhole tubing 3, the downhole tubing 3 is guided into the outer anchoring cylinder 1 of the retrieval device by the guiding action of the guide shoe 103, while the expanding anchor claw 201 of the inner anchoring sleeve 2 is inserted into the interior of the downhole tubing 3.

[0038] Subsequently, valve ball 6 is inserted from the wellhead and tubing is pressurized on the surface. The pressure inside the tubing pushes the conical hollow piston 4 downward. During the downward movement of the conical hollow piston 4, its locking section first squeezes and shears the shear pin 7, causing the conical head at the bottom of the conical hollow piston 4 to move downward. As the conical hollow piston 4 continues to move downward, its bottom conical head forces the expanding anchor claw 201 to expand radially outward, tightly engaging with the inner wall of the downhole tubing 3, forming an outward anchoring force; at the same time, the tension generated by the outward expansion of the expanding anchor claw 201 firmly engages the outer wall of the downhole tubing 3 with the inner engagement teeth 101 of the inner wall of the outer anchoring cylinder 1, forming external anchoring.

[0039] To eliminate the risk of backlash, a one-way locking mechanism between the conical hollow piston and the outer anchoring cylinder provides mechanical locking, preventing loosening of the engagement during vibration or load changes. Ultimately, this tool forms a stable pincer-like engagement structure on the inner and outer walls of the well tubing, achieving reliable anchoring and significantly improving the success rate of salvage operations.

[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. The patent protection scope of the present utility model shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present utility model shall also be included within the protection scope of the present utility model.

Claims

1. A pipe retrieval device, characterized in that, It includes an outer anchoring cylinder and an inner anchoring sleeve. The lower end of the outer anchoring cylinder is provided with a sleeve anchoring section. The inner wall of the sleeve anchoring section is provided with internal interlocking teeth. The inner anchoring sleeve is fixed in the outer anchoring cylinder. An expansion anchor claw that can be inserted into the well tubing is provided on the inner anchoring sleeve. The back of the expansion anchor claw is provided with external interlocking teeth. A conical hollow piston is installed in the inner anchoring sleeve. By throwing a ball into the conical hollow piston to pressurize it, the expansion anchor claw can be driven to expand outward to anchor the inner wall of the well tubing.

2. The oil pipe retrieval device according to claim 1, characterized in that, The lower end of the expanding anchor claw converges towards the center in the initial state to form an inverted cone shape.

3. The oil pipe retrieval device according to claim 1 or 2, characterized in that, The upper end of the hollow cone piston is provided with a position locking section, and a one-way locking mechanism that only allows the hollow cone piston to move downward is provided between the position locking section and the outer anchoring cylinder.

4. The oil pipe retrieval device according to claim 3, characterized in that, The one-way locking mechanism is a ratchet mechanism or a one-way clamp mechanism.

5. The oil pipe retrieval device according to claim 3, characterized in that, A shear pin is also provided between the position locking section and the outer anchoring cylinder to lock the initial position of the cone-shaped hollow piston. When it is in the initial position, the cone-shaped hollow piston is locked by the shear pin and cannot move downward, and does not act on the expanding anchor claw.

6. The oil pipe retrieval device according to claim 1, 2, 4, or 5, characterized in that, The outer anchoring cylinder includes a separate upper section and a lower section, and the inner anchoring sleeve is provided with an adapter. The upper section and the lower section are respectively threadedly connected to the adapter.

7. The oil pipe retrieval device according to claim 1, 2, 4, or 5, characterized in that, Both the internal and external biting teeth have wedge-shaped cross sections.

8. The oil pipe retrieval device according to claim 1, 2, 4, or 5, characterized in that, The internal engagement teeth are helical teeth, formed by machining threads on the inner wall of the outer anchoring cylinder.

9. The oil pipe retrieval device according to claim 1, 2, 4, or 5, characterized in that, The inner anchor sleeve has multiple expansion anchor claws, which are evenly distributed around the center line of the inner anchor sleeve.

10. The oil pipe retrieval device according to claim 1, 2, 4, or 5, characterized in that, The lower end of the outer anchoring cylinder is provided with a guide shoe.

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