Downhole milling and fishing integrated anti-sticking tool

Abstract

The application relates to the technical field of oil and gas well workover tool, and particularly discloses a downhole milling and fishing integrated anti-sticking tool which comprises an outer cylinder, a mandrel, a grinding head, slips and a centralizing block; the centralizing block is arranged in a radial sliding mode along the outer cylinder; an adjusting rod on the centralizing block is matched with a guide groove at the lower end of the mandrel, so that when the tool is lowered, the multiple centralizing blocks move synchronously and limit the center of the outer cylinder; the slip is provided with a sliding groove, a connecting rod drives a guide rod to move along the sliding groove, so that the slip is inwardly closed and holds the fish when the slip is pulled up; when the mandrel is pulled up, the adjusting rod is separated from the guide groove, so that the centralizing block is switched from the synchronous state to an asynchronous avoiding state capable of being independently extended and retracted; the application can keep the grinding head centered when the tool is lowered, and allows the centralizing block to be independently retracted and avoided after the fish is held and pulled up, so that the risk of sticking in the process of pulling up the fish is reduced.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well workover tools, specifically to an integrated downhole milling and retrieval anti-sticking tool. Background Technology

[0002] During oil and gas well production, workover, and intervention operations, debris such as bridge plugs, tubing subs, tool remnants, sand-clamped parts, and deformed metal parts may be left behind in the wellbore. After long-term exposure to corrosion, compression, sand accumulation, or casing deformation, these debris often develop burrs, flaked edges, deflection, scale buildup, or irregular deformation at the top. Directly using conventional retrieval tools can easily lead to problems such as the debris failing to enter the retrieval chamber, slips getting stuck, tool wear, and jamming during retrieval. Therefore, in downhole debris handling operations, it is usually necessary to first mill and trim the top of the debris before using slips, a retrieval tube, or a retrieval spear to grab and lift it.

[0003] Retractable milling and fishing tools have been disclosed in related technologies. For example, patent document CN201027515Y discloses a retractable milling and fishing tool, which includes an upper connector, a milling sleeve, a milling shoe, and fishing slips. It can retrieve objects dropped into the well after milling using the fishing slips. This type of tool combines milling and fishing into a single tool, reducing the number of tripping operations and improving fishing efficiency.

[0004] Patent document CN201090165Y discloses a drillable bridge plug milling and retrieval tool, which includes an outer cylinder, slips, a limiting sleeve, a retractable locking sleeve, a fixing ring, and a milling shoe. It enables milling and retrieval to be completed in one operation, and the tool can be safely withdrawn when jammed during operation via the retractable locking sleeve. This solution focuses on the withdrawal problem after jamming during milling and retrieval; it ensures safe tool retrieval by allowing the slips to loosen through breakage or release of the locking sleeve.

[0005] Chinese patent document CN107288567B discloses a retractable milling and fishing integrated device and its fishing method. Through the cooperation of the milling shoe, slip outer cylinder, release ring, and slips, it achieves the retrieval of fish that has fallen during the milling process and maintains the slips' grip on the fish during the fishing process. This solution can retrieve fish while milling the top of the fish, reducing the risk of the fish falling back to the bottom of the well after retrieval.

[0006] The relevant technologies still have shortcomings: they mainly focus on the integration of milling and fishing, and the withdrawal through slip release or tool release after jamming. They do not fully consider the different requirements of the tool for the straightening state at different operation stages. When the tool is lowered close to the fish, the straightening structure needs to support it synchronously so that the grinding head is centered and aligned with the top of the fish to reduce the risk of uneven grinding and skewed introduction. When the slip clamps the fish and is lifted, the tool and the fish form a whole. The fish may be in an eccentric state, and there may be steps, diameter reduction, sand bridges or other obstructions on the well wall or casing. If the straightening structure is still synchronously centered at this time, it is easy to form a rigid top between the straightening block, outer cylinder or fish and the well wall, causing the fish to get stuck when lifted. Even if the ordinary straightening block can retract, if its extreme retraction position still forms a right angle or shoulder, it is easy to get caught on the well wall step when lifting again, causing secondary jamming. Summary of the Invention

[0007] This application provides an integrated anti-jamming tool for downhole milling and fishing, which aims to solve the problem that in related technologies, milling and fishing tools need to be centered during lowering, and when the fish is lifted, forced centering can easily cause jamming of the straightening structure, the fish, or the outer cylinder with the well wall steps or the casing diameter reduction section.

[0008] This application discloses an integrated anti-jamming tool for downhole milling and fishing, comprising an outer cylinder, a mandrel disposed within the outer cylinder, a grinding head disposed at the lower end of the outer cylinder, and slips disposed within the outer cylinder. Multiple centering blocks are spaced circumferentially on the outer cylinder, and these centering blocks slide radially along the outer cylinder. Each centering block is equipped with an adjusting rod. The lower end of the mandrel has multiple guide grooves that correspond one-to-one with the adjusting rods. The guide grooves are used to restrict the synchronous movement of the multiple centering blocks via the adjusting rods when the tool is lowered, ensuring the outer cylinder remains centered. Each slip has a sliding groove. The mandrel is connected to a connecting rod, which is connected to a guide rod extending into the sliding groove. The connecting rod is used to move the guide rod along the sliding groove when the tool is lifted, causing the slips to move inward and clamp the fish. When the tool is lifted, the outer cylinder experiences frictional resistance from the well wall, causing the mandrel to move upward relative to the outer cylinder before it. After the mandrel moves upward, the adjusting rod disengages from the guide groove, switching the multiple centering blocks from a synchronous movement state to a non-synchronous avoidance state where they can extend and retract independently.

[0009] The effect is as follows: When the tool is lowered, multiple adjusting rods engage with their corresponding guide slots, and multiple centering blocks are synchronously constrained by the mandrel, enabling them to collectively center the outer cylinder, ensuring the grinding head is stably aligned with the top of the fish, reducing uneven grinding and skewed entry. When the tool begins to lift, the outer cylinder experiences frictional resistance from the well wall, causing the mandrel to move upward relative to the outer cylinder. This upward movement, on the one hand, drives the slips to move inward and clamp the fish through the connecting rod and guide rod; on the other hand, it causes the adjusting rods to disengage from the guide slots, freeing the multiple centering blocks from synchronous constraint. Instead, they can retract and reset independently based on local obstructions from the well wall, casing diameter reduction, or steps. Therefore, the tool has a centering entry capability during the lowering phase and a non-synchronous avoidance capability during the lifting phase, reducing the risk of jamming during the fish lifting process.

[0010] Preferably, the mandrel and the outer cylinder are rotatably arranged, and a torsion spring is provided between the mandrel and the outer cylinder. The torsion spring has a preload in the initial state. A locking block is provided on the inner side of the outer cylinder, and a limiting groove is provided on the mandrel. The locking block abuts against one end of the limiting groove to limit the initial relative rotational position between the mandrel and the outer cylinder. A limiting block is provided inside the outer cylinder to limit the extreme positions of the mandrel's axial upward and axial downward movement relative to the outer cylinder.

[0011] Its effects are as follows: by cooperating with the locking block and the limiting groove, the initial relative rotational position between the mandrel and the outer cylinder can be limited, so that the mandrel remains stable during normal lowering and grinding; by limiting the upper and lower limits of the mandrel by the limiting block, the mandrel can have a certain axial sliding stroke when the tool is lifted, avoiding excessive upper movement or insufficient reset of the mandrel, thereby improving the stability of the clamping action of the slip and the synchronous action of the straightening block.

[0012] Preferably, multiple guide grooves are provided on the lower end face of the mandrel and are arranged at intervals along the circumference of the mandrel. Each guide groove is correspondingly engaged with an adjusting rod. The guide grooves extend along the circumference of the mandrel and have a guide surface for driving the adjusting rod to move radially. When the rotational resistance of the outer cylinder increases, the mandrel rotates relative to the outer cylinder and causes the torsion spring to undergo further torsional deformation. The adjusting rod moves along the corresponding guide groove to drive multiple straightening blocks to retract inward together, thereby reducing the outer peripheral support size of the tool.

[0013] Its effect is as follows: multiple guide grooves correspond one-to-one with multiple adjusting rods, so that each centralizing block has a clear guiding constraint path, which can avoid the problem of uneven force or asynchronous movement when multiple centralizing blocks share the same guiding structure. When the outer cylinder is subjected to abnormal rotational resistance, the mandrel rotates relative to the outer cylinder, the torsion spring undergoes torsional deformation, and at the same time, each adjusting rod moves along the guide surface of the corresponding guide groove, causing multiple centralizing blocks to retract inward together, reducing the outer peripheral support size of the tool, thereby reducing the risk of the centralizing blocks rigidly hitting the well wall and causing jamming during the lowering or grinding stage.

[0014] Preferably, each straightening block is connected to a telescopic rod, one end of which abuts against the connecting rod and the other end is connected to the straightening block. A spring is installed inside the telescopic rod, which is used to push the straightening block to extend radially outward along the outer cylinder in the initial state. When the adjusting rod is disengaged from the guide groove, each straightening block extends and retracts radially through the corresponding telescopic rod, so that a single straightening block can retract or reset independently relative to other straightening blocks.

[0015] Its effect is as follows: one end of the telescopic rod abuts against the connecting rod, and the other end connects to the centralizing block, allowing the connecting rod to serve as the inner support base for the telescopic rod. The spring inside the telescopic rod provides the centralizing block with an outward elastic force. After the adjusting rod is disengaged from the guide groove, each centralizing block is no longer constrained by synchronous guidance, but extends and retracts independently through the corresponding telescopic rod. During the lifting process of the fish, when a centralizing block on one side is locally squeezed by the well wall step, casing diameter reduction, or sand bridge, only the centralizing block on that side compresses the corresponding telescopic rod and retracts inward, while other centralizing blocks can still remain extended outward or partially extended, so that the tool can form a local offset avoidance while maintaining a certain centralizing effect.

[0016] Preferably, the outer side of the straightening block is provided with a crescent-shaped support surface, which extends in an arc along the circumference of the outer cylinder, and the middle part of the crescent-shaped support surface protrudes outward, while the two ends narrow towards the outer cylinder.

[0017] Its effects are as follows: the middle part of the crescent-shaped stabilizer can form stable contact with the well wall or casing inner wall during lowering, playing a role in centering and centering; the two ends of the crescent-shaped stabilizer narrow towards the outer cylinder, which can reduce the possibility of sharp snagging points or shoulders forming at the ends of the stabilizer. Thus, the stabilizer can not only stably center the block during lowering, but also provide a relatively smooth contact transition when deviation occurs during lifting, reducing scraping and friction between the stabilizer and the well wall.

[0018] Preferably, the upper end of the straightening block is provided with an upper sliding inclined surface, and the lower end of the straightening block is provided with a lower sliding inclined surface. The upper sliding inclined surface is used to contact the well wall step or the narrowing part during the lifting process and guide the straightening block to retract inward. The lower sliding inclined surface is used to guide and avoid well wall protrusions or foreign objects during the lowering process.

[0019] Its effects are as follows: the sliding deflector can guide and avoid wellbore protrusions, casing diameter reductions, or foreign objects in the well during tool descent, reducing the hard collision between the lower end of the centralizing block and the obstruction; the upper sliding deflector can convert the axial resistance force into a radial inward force pushing the centralizing block when it encounters wellbore steps, diameter reduction sections, or sand bridges during tool descent, making it easier for the centralizing block to be pushed back. Therefore, the centralizing block has guiding and obstacle-avoiding capabilities in both descent and descent directions.

[0020] Preferably, when the centralizing block is contracted to its limit position, the upper sliding ramp is at least partially exposed on the outer periphery of the outer cylinder, so that the centralizing block can still contact the well wall step or the reduced diameter part through the ramp when it is in the limit contraction state.

[0021] The effect is that even if the centralizing block is subjected to significant compression and retracts to its limit position, the exposed portion of the centralizing block along the lifting direction remains a sloped structure, rather than a right-angled edge or a stepped edge. This allows the wellbore steps or reduced diameter sections to still slide relative to each other along the upward sliding slope during continued lifting, preventing the centralizing block from forming new entrapment points in its shortest retraction state and improving the reliability of the tool through complex well sections.

[0022] Preferably, there are multiple slips, which are spaced apart circumferentially along the outer cylinder. The sliding groove gradually moves away from the axis of the mandrel in the upward lifting direction. The guide rod extends into the sliding groove and is used to move along the sliding groove during lifting to pull the slips inward toward the axis of the mandrel.

[0023] Its effect is that, through the cooperation of the guide rod and the inclined sliding groove, the upward movement of the connecting rod can be converted into the radial inward movement of the slip. As the sliding groove gradually moves away from the axis of the spindle along the upward direction, the guide rod can pull the slip inward through the groove wall when it moves upward with the connecting rod, so that the slip actively clamps the falling fish in the initial stage of upward movement, improving the reliability of the grasping after the falling fish enters the clamping area.

[0024] Preferably, the slip has slip teeth on the side facing the fish, and a guide slope is provided at the lower end of the slip. The guide slope is used to guide the fish entering the outer cylinder so that the fish enters the clamping area of ​​the slip. The slip teeth are used to clamp the fish after the guide rod drives the slip to move inward.

[0025] Its effects are as follows: the guide ramp guides the fish entering the outer cylinder, directing it into the clamping area of ​​the slip, reducing the hard contact between the top of the fish and the bottom of the slip; the slip teeth engage with the outer wall of the fish after the slip closes inward, improving clamping stability. Thus, the slip guides the fish during the lowering phase through the guide ramp, and actively clamps it during the lifting phase through the slip teeth, clearly defining the functional division between the two phases.

[0026] Preferably, the outer cylinder is provided with a retrieval chamber and a guide platform. The guide platform is located between the grinding head and the slip. The grinding head is used to grind and trim the top of the fish, and the guide platform is used to guide the fish after it has been trimmed by the grinding head to the clamping area of ​​the slip.

[0027] Its effects are as follows: the grinding head first trims the burrs, folds, scale, or deformed parts on the top of the fish, making the shape of the top of the fish more conducive to entering the outer cylinder; the guide table guides the fish trimmed by the grinding head to the clamping area of ​​the slip, which can reduce the slip biting caused by the fish entering at an angle, and make the grinding, guiding and clamping actions completed continuously in the same tool.

[0028] By adopting the above technical solution, the beneficial effects of this application are as follows: 1. This application uses multiple guide grooves at the lower end of the mandrel to correspond one-to-one with the adjusting rods on multiple centering blocks. During the tool lowering process, each guide groove restricts the movement trajectory of the corresponding adjusting rod, so that multiple centering blocks move synchronously and extend or retract radially along the outer cylinder, thereby forming a central limit on the outer cylinder. This enables the grinding head to be more stably aligned with the top of the fish during the lowering milling process, reducing the risk of uneven grinding of the grinding head, skewed introduction of the fish, and scraping between the tool and the well wall.

[0029] 2. This application utilizes the sliding grooves on the connecting rod, guide rod, and slips. When the tool begins to lift, the outer cylinder experiences frictional resistance from the well wall, causing the mandrel to move upward relative to the outer cylinder. The mandrel then drives the connecting rod and guide rod upward. The guide rod moves along the sliding grooves and pulls multiple slips towards the axis of the mandrel, thereby allowing the slips to actively clamp the fish that has fallen into the clamping area. Thus, the lifting action itself can trigger the slips to clamp the fish, eliminating the need for a separate special grabbing tool and improving the reliability of grabbing the fish after it enters the retrieval chamber.

[0030] 3. This application utilizes the axial upward movement of the mandrel relative to the outer cylinder to disengage the adjusting rod on the centralizing block from the guide groove corresponding to the lower end of the mandrel, thereby releasing the synchronization restriction between multiple centralizing blocks. After the synchronization is released, each centralizing block can extend and retract independently via its corresponding telescopic rod. When the tool lifts the fish, if any centralizing block encounters a wellbore step, casing diameter reduction, or sand bridge obstruction, it can retract inward independently, while the other centralizing blocks can still maintain support, allowing the tool to deflect and avoid obstruction caused by forced centering.

[0031] 4. This application sets the straightening block with a crescent-shaped straightening face, an upper slip ramp, and a lower slip ramp. This allows the straightening block to stably contact the well wall and straighten itself when lowered. When it encounters a step or a narrowing section during lifting, the upper slip ramp can convert the axial resistance force into a radial retraction force, guiding the straightening block to avoid it. When the straightening block retracts to its limit position, the upper slip ramp is still at least partially exposed, allowing the straightening block to still contact the step through the ramp even in the limit retraction state. This avoids the formation of a right-angle hook structure and improves the tool's ability to pass through steps, narrowing sections, or sand bridge sections. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of this application.

[0033] Figure 2 This is a schematic cross-sectional view of the overall structure of this application.

[0034] Figure 3This is a schematic diagram of the assembly structure of the outer cylinder and the mandrel in this application.

[0035] Figure 4 This is a schematic diagram of the mandrel structure in this application.

[0036] Figure 5 This is a schematic diagram of the mating structure between the mandrel and the straightening block in this application.

[0037] Figure 6 This is a schematic diagram of the structure of the straightening block in this application.

[0038] Figure 7 This is a schematic diagram of the structure of the slip and connecting rod in this application.

[0039] Figure 8 This is a schematic diagram of the structure of the Kava in this application.

[0040] Figure 9 This is a schematic diagram of the limit block in this application.

[0041] Figure 10 This is a schematic diagram of the torsion spring in this application.

[0042] Figure label: 1. Outer cylinder; 11. Clamping block; 12. Retrieval chamber; 13. Guide platform; 14. Limiting block; 2. Mandrel; 21. Guide groove; 22. Limiting groove; 3. Grinding head; 4. Clamping slip; 41. Sliding groove; 42. Clamping slip teeth; 43. Guide inclined surface; 5. Straightening block; 51. Adjusting rod; 52. Crescent-shaped straightening front; 53. Upper sliding inclined surface; 54. Lower sliding inclined surface; 6. Connecting rod; 7. Guide rod; 8. Torsion spring; 9. Telescopic rod. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0044] like Figures 1 to 10As shown, this application discloses an integrated downhole milling and fishing anti-jamming tool, comprising an outer cylinder 1, a mandrel 2, a grinding head 3, slips 4, a centralizing block 5, a connecting rod 6, a guide rod 7, a torsion spring 8, and a telescopic rod 9. The outer cylinder 1 is a hollow cylindrical structure. The mandrel 2 is arranged axially within the outer cylinder 1. The grinding head 3 is located at the lower end of the outer cylinder 1, and the slips 4 are arranged within the outer cylinder 1 and above the grinding head 3. A fishing cavity 12 is formed within the outer cylinder 1 for fish to enter. A guide platform 13 is provided within the fishing cavity 12, located between the grinding head 3 and the slips 4. Multiple centralizing blocks 5 are spaced apart circumferentially along the outer cylinder 1 and are slidably mounted on the outer cylinder 1 radially. The connecting rod 6 is connected to the mandrel 2, the guide rod 7 is connected to the connecting rod 6, the torsion spring 8 is located between the mandrel 2 and the outer cylinder 1, and the telescopic rod 9 is located between the connecting rod 6 and the centralizing block 5.

[0045] The outer cylinder 1 serves as the external support for the tool. The upper end of the mandrel 2 inside the outer cylinder 1 can be connected to the workover string, tubing, or drill string via a threaded joint. The lower end of the outer cylinder 1 can be connected to the grinding head 3 via thread, welding, or integral machining. The outer cylinder 1 is sleeved around the mandrel 2 and can slide axially relative to the mandrel 2. When the tool is lifted, the lifting force is first transmitted to the mandrel 2. The outer cylinder 1 moves upward with a lag due to frictional resistance between itself and the well wall, casing inner wall, or foreign objects in the well, thus causing the mandrel 2 to move upward relative to the outer cylinder 1 first. This relative upward movement, on the one hand, causes the connecting rod 6 and guide rod 7 to move upward, causing the slips 4 to move inward and clamp the fish; on the other hand, it causes the adjusting rod 51 to disengage from the corresponding guide groove 21, releasing the synchronous constraint of the multiple centering blocks 5 and switching to a asynchronous avoidance state. Because downhole milling and fishing tools need to withstand rotational torque, axial tension, well fluid erosion, and sand abrasion during operation, load-bearing components such as the outer cylinder 1, mandrel 2, and connecting rod 6 can be made of high-strength alloy steel. Wear-resistant bushings, sealing rings, or sand-proof rings can be installed at the relative movement points of the outer cylinder 1 and mandrel 2 to reduce the entry of mud and sand into the movement gap and improve the stability of the tool in sand-containing well fluids.

[0046] The grinding head 3 is located at the lower end of the outer cylinder 1 and is used to grind and repair burrs, flaked edges, scale, hardened sand deposits, or irregularly deformed parts on the top of the fish when the tool is lowered to the top. The grinding head 3 can adopt the annular grinding structure commonly used in downhole milling tools. Its end face or inner edge can be inlaid with carbide teeth, tungsten carbide particles, or wear-resistant layers to enhance the grinding head 3's ability to repair deformed metal edges, bridge plug remnants, or short sections of the tubing.

[0047] A guide platform 13 is positioned between the grinding head 3 and the slip 4. The guide platform 13 can be configured as a conical guide surface or an arc-shaped transition surface, allowing the fish, after being trimmed by the grinding head 3, to enter the retrieval chamber 12 along the guide platform 13 and be guided to the clamping area of ​​the slip 4. By guiding the fish through the guide platform 13, the problem of the slip 4 biting off-center due to the fish entering at an angle can be reduced.

[0048] The centralizing blocks 5 are spaced apart circumferentially along the outer cylinder 1, preferably in three evenly distributed circumferentially, but can also be four or more depending on the wellbore diameter and tool outer diameter. The outer cylinder 1 has mounting windows corresponding to the centralizing blocks 5, and the centralizing blocks 5 are slidably mounted within these windows radially along the outer cylinder 1. Guide rails, limiting edges, or dovetail-shaped limiting grooves can be provided on both sides of the mounting windows, and guide protrusions that cooperate with the centralizing blocks 5 are provided on both sides, enabling the centralizing blocks 5 to stably extend and retract radially and preventing them from detaching from the outer cylinder 1.

[0049] An adjusting rod 51 is provided on the straightening block 5, and multiple guide grooves 21 are provided on the lower end face of the mandrel 2. The multiple guide grooves 21 are arranged at intervals along the circumference of the mandrel 2 and correspond one-to-one with the adjusting rods 51 on the multiple straightening blocks 5. Each adjusting rod 51 extends into the corresponding guide groove 21. The guide groove 21 can be an arc-shaped groove extending along the circumference of the mandrel 2, or a curved groove with a radial gradient trend. A guide surface is formed in the guide groove 21 for driving the adjusting rod 51 to move radially. In the lowered state, the multiple adjusting rods 51 are constrained by the corresponding guide grooves 21, so that the multiple straightening blocks 5 move synchronously, thereby forming a central limit on the outer cylinder 1, so that the grinding head 3 can be stably aligned with the top of the fish.

[0050] The mandrel 2 is rotatably mounted to the outer cylinder 1, and a torsion spring 8 is provided between the mandrel 2 and the outer cylinder 1. The torsion spring 8 has a preload in its initial state. A retaining block 11 is provided on the inner side of the outer cylinder 1, and a limiting groove 22 is provided on the mandrel 2. The retaining block 11 abuts against one end of the limiting groove 22 to limit the initial relative rotational position between the mandrel 2 and the outer cylinder 1. A limiting block 14 is also provided inside the outer cylinder 1. The limiting block 14 is used to limit the extreme positions of the mandrel 2 relative to the outer cylinder 1 in axial upward and axial downward movement, so that the mandrel 2 can rotate relative to the outer cylinder 1 within a set angle and can also move axially relative to the outer cylinder 1 within a set stroke when the tool is lifted.

[0051] When the outer cylinder 1 experiences significant rotational resistance during lowering or grinding, the mandrel 2 can rotate relative to the outer cylinder 1, causing the torsion spring 8 to undergo further torsional deformation. At this time, multiple adjusting rods 51 move along the guide surfaces of their corresponding guide grooves 21, and multiple centering blocks 5 retract inward together with the cooperation of the guide grooves 21 and the adjusting rods 51, reducing the outer peripheral support dimension of the tool. After the abnormal rotational resistance is relieved, the torsion spring 8 releases its torsional energy and drives the mandrel 2 to reset, allowing the centering blocks 5 to return to their synchronous center limit state.

[0052] Multiple slippers 4 are arranged at intervals along the circumference of the outer cylinder 1, preferably three slippers evenly distributed circumferentially. The slippers 4 are located within the retrieval chamber 12 and have sliding grooves 41 that gradually move away from the axis of the mandrel 2 in the upward lifting direction. The mandrel 2 is connected to a connecting rod 6, which is connected to a guide rod 7 that extends into the sliding groove 41. When the tool is lifted, the mandrel 2 moves the connecting rod 6 upward, which in turn moves the guide rod 7 along the sliding groove 41. The guide rod 7 pulls the slippers 4 inward toward the axis of the mandrel 2 through the groove wall of the sliding groove 41, causing the multiple slippers 4 to converge inward and clamp the fallen fish.

[0053] The slipper 4 has slipper teeth 42 on the side facing the fish, and a guide ramp 43 at its lower end. When the fish enters the outer cylinder 1, the guide ramp 43 guides the fish into the clamping area of ​​the slipper 4. After the fish is in place, the guide rod 7 moves the slipper 4 inward, and the slipper teeth 42 engage with the outer wall of the fish, thus clamping it. This structure does not allow the fish to enter by the slipper 4 moving backward, but rather guides the fish into the clamping area of ​​the slipper 4 through the guide ramp 43, and then the slipper 4 actively clamps it.

[0054] Each straightening block 5 is connected to a corresponding telescopic rod 9. One end of the telescopic rod 9 abuts against the connecting rod 6, and the other end is connected to the straightening block 5. A spring is installed inside the telescopic rod 9. The telescopic rod 9 can adopt a sleeve-type telescopic structure, including an outer rod, an inner sliding rod, and a spring. The inner sliding rod is connected to the straightening block 5, and the outer rod abuts against or supports the connecting rod 6. The spring is used to push the straightening block 5 to extend radially outward along the outer cylinder 1 in the initial state, so that the straightening block 5 can maintain its elastic straightening ability.

[0055] When the tool begins to lift, the outer cylinder 1 experiences frictional resistance from the well wall or the dropped fish, and the mandrel 2 moves upward relative to the outer cylinder 1 before the outer cylinder 1. After the mandrel 2 moves upward, the adjusting rod 51 on the centering block 5 disengages from the guide groove 21 corresponding to the lower end of the mandrel 2. After the adjusting rod 51 disengages, the multiple centering blocks 5 are no longer synchronously constrained by the guide groove 21, but instead extend and retract radially through their respective telescopic rods 9. At this time, the tool switches from the synchronous center-limiting state of the lowering stage to the asynchronous avoidance state of the lifting stage. If a centering block 5 on one side encounters a well wall step, casing diameter reduction, or sand bridge during the lifting of the dropped fish, that centering block 5 can compress the corresponding telescopic rod 9 and retract inward individually, while the other centering blocks 5 can still remain extended or partially extended, allowing the outer cylinder 1 and the clamped dropped fish to make a small offset to avoid collisions.

[0056] The outer side of the centering block 5 is provided with a crescent-shaped centering face 52. The crescent-shaped centering face 52 extends in an arc along the circumference of the outer cylinder 1, and the middle part of the crescent-shaped centering face 52 protrudes outward, while the two ends narrow towards the outer cylinder 1. When the crescent-shaped centering face 52 is lowered, it can form a stable contact with the well wall or the inner wall of the casing, playing a role in centering and centering. After its two ends are narrowed, it can reduce the possibility of sharp corners or shoulders forming at the ends of the centering block 5, and reduce the risk of scraping against the well wall.

[0057] The upper end of the centralizing block 5 is provided with an upper slip ramp 53, and the lower end is provided with a lower slip ramp 54. The lower slip ramp 54 is used to guide and avoid well wall protrusions, casing diameter reduction, or foreign objects in the well during the tool's descent. The upper slip ramp 53 is used to contact the well wall step or diameter reduction part during the tool's descent and convert the axial resistance force into a component force that pushes the centralizing block 5 to retract radially. When the centralizing block 5 is retracted to its limit position, the upper slip ramp 53 is still at least partially exposed on the outer periphery of the outer cylinder 1, so that even when the centralizing block 5 is in its shortest retraction state, it still contacts the well wall step or diameter reduction part through the ramp, avoiding the formation of right angle edges or shoulders that could cause secondary jamming.

[0058] The working principle of this application is as follows: When the tool is lowered into the well, the torsion spring 8 is in a pre-tightened state, the locking block 11 abuts against one end of the limiting groove 22, the spindle 2 and the outer cylinder 1 maintain their initial relative rotational position, and the spindle 2 is simultaneously restricted by the limiting block 14 inside the outer cylinder 1 and is in its initial axial position. At this time, the adjusting rods 51 on the multiple centering blocks 5 extend into the guide grooves 21 corresponding to the lower end of the spindle 2, and the multiple centering blocks 5 are in a synchronous outward extension state, forming a central limit on the outer cylinder 1, so that the grinding head 3 can be aligned with the top of the fish relatively stably.

[0059] During the lowering or grinding process, if the outer cylinder 1 experiences abnormal rotational resistance, the mandrel 2 rotates relative to the outer cylinder 1, causing the torsion spring 8 to undergo further torsional deformation. Multiple adjusting rods 51 move along their corresponding guide grooves 21, driving multiple straightening blocks 5 to retract inwards together, thus synchronously reducing the tool's diameter. After the abnormal rotational resistance is relieved, the torsion spring 8 releases its torsional energy and drives the mandrel 2 to reset, and the straightening blocks 5 return to their synchronous center limit state.

[0060] Once the tool reaches the fish-dropping position, the grinding head 3 first grinds and trims the burrs, flanges, scale, or irregularly deformed parts on the top of the fish. After grinding and trimming, the fish enters the clamping area of ​​the slip 4 under the guidance of the guide table 13 and the guide inclined surface 43.

[0061] When the lifting begins, the outer cylinder 1 experiences frictional resistance from the well wall or the fallen fish, causing the mandrel 2 to move upward relative to the outer cylinder 1. As the mandrel 2 moves upward, it drives the connecting rod 6 upward, which in turn drives the guide rod 7 to move along the sliding groove 41 on the slip 4. Because the sliding groove 41 gradually moves away from the axis of the mandrel 2 in the lifting direction, the guide rod 7, as it moves upward, pulls the slip 4 inward through the sliding groove 41, causing multiple slips 4 to clamp the fallen fish. Simultaneously, the upward movement of the mandrel 2 causes the adjusting rod 51 to disengage from the corresponding guide groove 21, releasing the synchronous restriction on the multiple centering blocks 5 and switching to a asynchronous avoidance state where they extend and retract independently via the telescopic rod 9.

[0062] As the tool continues to lift, the slip 4 maintains its grip on the fallen fish, and the outer cylinder 1 and the fallen fish move upwards as a whole. If one side of the centering block 5 encounters a wellbore step, casing reduction, or sand bridge, that side's centering block 5 retracts inwards individually via the corresponding telescopic rod 9, while the other centering blocks 5 remain supported, allowing the tool to deflect and avoid the obstruction. After the tool passes the obstruction, the spring inside the telescopic rod 9 pushes the corresponding centering block 5 to extend outwards again, and the tool returns to its elastic centering state. If the centering block 5 is compressed to its limit position, the upper slip ramp 53 remains at least partially exposed and in contact with the step or reduction, allowing the tool to continue lifting along the ramp and reducing the risk of jamming.

[0063] This application can keep the tool centered and have synchronous diameter reduction capability during the grinding stage, and can also allow the straightening block 5 to avoid collisions asynchronously after the fish is lifted and clamped, thereby improving the stability and anti-jamming capability of downhole milling and fishing operations.

[0064] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A downhole integrated anti-sticking tool for milling and fishing, comprising an outer cylinder (1), a mandrel (2) arranged in the outer cylinder (1), a milling head (3) arranged at the lower end of the outer cylinder (1), and a slip (4) arranged in the outer cylinder (1), characterized in that, Multiple centering blocks (5) are spaced circumferentially on the outer cylinder (1). The centering blocks (5) slide radially along the outer cylinder (1). An adjusting rod (51) is provided on the centering block (5). Multiple guide grooves (21) are provided at the lower end of the spindle (2) and correspond one-to-one with the adjusting rods (51). The guide grooves (21) are used to restrict the synchronous movement of multiple centering blocks (5) by the adjusting rods (51) when the tool is lowered, so as to keep the outer cylinder (1) centered. A sliding groove (41) is provided on the slip (4). A connecting rod (6) is connected to the spindle (2). The connecting rod (6) is connected to a guide rod (7) that extends into the sliding groove (41). The connecting rod (6) is used to drive the guide rod (7) to move along the sliding groove (41) when the tool is lifted, so that multiple slips (4) move inward and clamp the fish. When the tool is lifted, the outer cylinder (1) is subjected to the frictional resistance of the well wall, so that the mandrel (2) moves upward relative to the outer cylinder (1) first. After the mandrel (2) moves upward, the adjusting rod (51) is dislodged from the guide groove (21), so that multiple straightening blocks (5) switch from synchronous movement state to asynchronous avoidance state that can extend and retract independently.

2. The anti-sticking tool of claim 1, wherein, The spindle (2) is rotatably mounted to the outer cylinder (1). A torsion spring (8) is provided between the spindle (2) and the outer cylinder (1). The torsion spring (8) has a preload in the initial state. A locking block (11) is provided on the inner side of the outer cylinder (1). A limiting groove (22) is provided on the spindle (2). The locking block (11) abuts against one end of the limiting groove (22) to limit the initial relative rotation position between the spindle (2) and the outer cylinder (1). A limiting block (14) is provided inside the outer cylinder (1). The limiting block (14) is used to limit the extreme positions of the spindle (2) moving upward and downward relative to the outer cylinder (1).

3. The anti-sticking tool of claim 2, wherein, Multiple guide grooves (21) are provided on the lower end face of the mandrel (2) and are arranged at intervals along the circumference of the mandrel (2). Each guide groove (21) is correspondingly engaged with an adjusting rod (51). The guide groove (21) extends along the circumference of the mandrel (2) and has a guide surface for driving the adjusting rod (51) to move radially. When the rotational resistance of the outer cylinder (1) increases, the mandrel (2) rotates relative to the outer cylinder (1) and causes the torsion spring (8) to undergo further torsional deformation. The adjusting rod (51) moves along the corresponding guide groove (21) to drive multiple straightening blocks (5) to retract inward together, thereby reducing the outer peripheral support size of the tool.

4. The anti-sticking tool of claim 1, wherein, Each straightening block (5) is connected to a telescopic rod (9). One end of the telescopic rod (9) abuts against the connecting rod (6), and the other end is connected to the straightening block (5). A spring is provided inside the telescopic rod (9). The spring is used to push the straightening block (5) to extend outward along the radial direction of the outer cylinder (1) in the initial state. When the adjusting rod (51) is dislodged from the guide groove (21), each straightening block (5) performs radial extension and retraction through the corresponding telescopic rod (9) so that a single straightening block (5) can retract or reset independently relative to other straightening blocks (5).

5. The anti-sticking tool of claim 4, wherein, The outer side of the straightening block (5) is provided with a crescent-shaped support surface (52). The crescent-shaped support surface (52) extends in an arc along the circumference of the outer cylinder (1), and the middle part of the crescent-shaped support surface (52) protrudes outward, while the two ends narrow towards the outer cylinder (1).

6. The anti-sticking tool of claim 5, wherein, The upper end of the straightening block (5) is provided with an upper sliding inclined surface (53), and the lower end of the straightening block (5) is provided with a lower sliding inclined surface (54). The upper sliding inclined surface (53) is used to contact the well wall step or the narrowing part during the lifting process and guide the straightening block (5) to retract inward. The lower sliding inclined surface (54) is used to guide and avoid well wall protrusions or foreign objects during the lowering process.

7. The anti-sticking tool of claim 6, wherein, When the centralizing block (5) is contracted to its limit position, the upper sliding inclined surface (53) is at least partially exposed on the outer periphery of the outer cylinder (1) so that the centralizing block (5) can still contact the well wall step or the reduced diameter part through the inclined surface in the limit contraction state.

8. The anti-sticking tool of claim 1, wherein, There are multiple slips (4), and the multiple slips (4) are spaced apart along the circumference of the outer cylinder (1). The sliding groove (41) gradually moves away from the axis of the spindle (2) along the lifting direction. The guide rod (7) extends into the sliding groove (41) and is used to move along the sliding groove (41) when lifting, so as to pull the slips (4) inward toward the axis of the spindle (2).

9. The anti-sticking tool of claim 8, wherein, The slip (4) has slip teeth (42) on the side facing the fish. The lower end of the slip (4) has an inlet ramp (43). The inlet ramp (43) is used to guide the fish into the outer cylinder (1) so that the fish enters the clamping area of ​​the slip (4). The slip teeth (42) are used to clamp the fish after the guide rod (7) drives the slip (4) to move inward.

10. The anti-sticking tool of claim 1, wherein, The outer cylinder (1) is provided with a retrieval chamber (12) and a guide platform (13). The guide platform (13) is located between the grinding head (3) and the slip (4). The grinding head (3) is used to grind and trim the top of the fish. The guide platform (13) is used to guide the fish after it has been trimmed by the grinding head (3) to the clamping area of ​​the slip (4).

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