Underground hydraulic flexible milling shoe structure

Abstract

The utility model discloses an underground hydraulic flexible milling shoe structure which is characterized in that a milling head and a top joint are movably sleeved together, a torque transmission mechanism is arranged at the movable sleeved part of the milling head and the top joint, and a liquid circulation hole is formed in the torque transmission mechanism; a piston installation cavity is formed between the periphery of the milling head and the adjacent step face of the inner hole of the top connector, the two ends of the liquid circulation hole are communicated with the piston installation cavity and the inner hole of the top connector respectively, the periphery of the milling head at the position of the piston installation cavity is sleeved with a piston, and limiting mechanisms are arranged on the milling head on the left side of the piston and the top connector. According to the utility model, by utilizing the dynamic characteristics of liquid fluid, closure is formed on drilling fluid through the end face of the inner hole, inner cavity pressure is generated, the thrust of the milling head is formed through the internal structure of the milling shoe and the area of the piston, the reverse acting force of the milling head is buffered, and the purpose of constant milling thrust value is achieved; and the dual purposes of protecting the milling tool and improving the milling efficiency are achieved.

Description

Technical Field

[0001] This utility model relates to a downhole hydraulic flexible grinding shoe structure, belonging to the technical field of oil and gas extraction equipment. Background Technology

[0002] In oil and gas extraction operations, milling operations are required in many situations, such as accident handling, window drilling, downhole casing repair, and packer milling. Milling tools are essential tools for downhole milling operations.

[0003] During downhole milling operations, a continuous and stable downward pressure needs to be applied to the milling tool to ensure its cutting performance. However, in actual use, the milling tool often operates at extremely deep depths. The downward pressure is applied by surface personnel intermittently lowering the drill string at the wellhead. The weight of the upper drill string acts on the milling tool. Each lowering of the drill string applies a specified pressure, which gradually decreases as the milling tool mills the lower drill string. This process is repeated, resulting in a constantly changing downward pressure during actual use – a force that decreases repeatedly.

[0004] The downward pressure acting on the milling tool is balanced by the reaction force between the milling teeth and the drill bit being milled. If the reaction force on the milling teeth is too small, the optimal milling effect cannot be achieved, leading to reduced efficiency. If the reaction force on the milling teeth is too large, it can easily cause tooth breakage. In actual operation, existing pressure application methods are not only inefficient but also frequently result in tooth breakage, rendering the milling tool unusable.

[0005] Therefore, a constant downward pressure can not only effectively prevent tooth breakage during tool grinding, but also maximize grinding efficiency. Utility Model Content

[0006] The purpose of this invention is to provide a downhole hydraulic flexible grinding shoe structure. This structure provides a constant downward pressure during use, effectively preventing tooth breakage during tool grinding and maximizing grinding efficiency.

[0007] The technical solution of this utility model is as follows: A downhole hydraulic flexible grinding shoe structure includes a milling head, which is movably sleeved with a top connector, and the inner holes of the two are interconnected. The end of the inner hole of the milling head is connected to the outside through the inner hole end face. A torque transmission mechanism is provided at the movable sleeve of the milling head and the top connector. A liquid flow hole is provided on the torque transmission mechanism. The outer periphery of the milling head on the left side of the torque transmission mechanism and the inner hole of the top connector are both stepped structures. A piston mounting chamber is formed between the adjacent stepped surfaces of the outer periphery of the milling head and the inner hole of the top connector. The two ends of the liquid flow hole are connected to the piston mounting chamber and the inner hole of the top connector, respectively. A piston is sleeved on the outer periphery of the milling head at the piston mounting chamber. The length of the piston is less than the length of the piston mounting chamber. A limit mechanism is provided on the milling head and the top connector on the left side of the piston.

[0008] In the aforementioned downhole hydraulic flexible grinding shoe structure, the limiting mechanism includes a limiting nut threaded onto the outer periphery of the milling head on the left side of the piston, and a limiting retaining ring with an inverted L-shaped structure threaded onto the top connector on the left side of the limiting nut.

[0009] In the aforementioned downhole hydraulic flexible grinding shoe structure, the torque transmission mechanism includes a rib on the outer periphery of the milling head, the rib being inserted into a groove on the inner wall of the top connector, and a liquid flow hole on the rib.

[0010] In the aforementioned downhole hydraulic flexible grinding shoe structure, multiple ribs and slots are evenly arranged.

[0011] In the aforementioned downhole hydraulic flexible grinding shoe structure, both the outer periphery and the inner wall of the piston are fitted with sealing elements.

[0012] The beneficial effects of this utility model are as follows: Compared with the prior art, this utility model sets a piston mounting chamber between the milling head and the top connector, and installs a piston inside it. The piston mounting chamber is connected to the inner hole through a liquid flow hole. Utilizing the fluid dynamic characteristics, the drilling fluid is intercepted through the end face of the inner hole, generating internal pressure. Then, through the internal structure of the milling shoe, the piston area is used to generate the thrust of the milling head while buffering the reverse force of the milling head, so as to achieve the purpose of constant milling thrust value and play a dual role in protecting the milling tool and improving milling efficiency. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of this utility model;

[0014] Figure 2 for Figure 1 A cross-sectional structural diagram.

[0015] Reference numerals: 1-milling head, 2-top connector, 3-inner hole end face, 4-torque transmission mechanism, 5-liquid flow hole, 6-piston mounting chamber, 7-piston, 8-limit nut, 9-limit retaining ring, 10-rib, 11-slot, 12-seal. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0017] An embodiment of this utility model: A downhole hydraulic flexible grinding shoe structure includes a milling head 1, which is movably sleeved with a top connector 2, and the inner holes of the two are interconnected. The end of the inner hole of the milling head 1 is connected to the outside through the inner hole end face 3. The end of the milling head 1 is also provided with end face milling teeth. A torque transmission mechanism 4 is provided at the movable sleeve of the milling head 1 and the top connector 2. A liquid flow hole 5 is provided on the torque transmission mechanism 4. The outer periphery of the milling head 1 on the left side of the torque transmission mechanism 4 and the inner hole of the top connector 2 are both stepped structures. A piston mounting chamber 6 is formed between the adjacent stepped surfaces of the outer periphery of the milling head 1 and the inner hole of the top connector 2. The two ends of the liquid flow hole 5 are connected to the piston mounting chamber 6 and the inner hole of the top connector 2, respectively. A piston 7 is sleeved on the outer periphery of the milling head 1 at the piston mounting chamber 6. The length of the piston 7 is less than the length of the piston mounting chamber 6. The left end of the piston 7 abuts against the stepped surface of the outer periphery of the milling head 1. A limit mechanism is provided on the milling head 1 and the top connector 2 on the left side of the piston 7.

[0018] The method for preventing tooth breakage using the downhole hydraulic flexible grinding shoe structure of this utility model utilizes the inner end face 3 of the milling head 1 to intercept the drilling fluid, generating internal cavity pressure. This internal cavity pressure enters the piston mounting chamber 6 through the liquid flow hole 5 and ultimately acts on the piston 7. Because the piston 7 abuts against the stepped surface of the milling head 1, it generates a constant thrust value acting on the milling head 1. Simultaneously, since a torque transmission mechanism 4 is provided between the milling head 1 and the top connector 2, the rotation of the top connector 2 will drive the milling head 1 to rotate together, enabling the milling head 1 to perform milling operations. The thrust value of the piston 7 acting on the milling head 1 remains constant when the drilling fluid discharge rate remains unchanged. Once the lower reaction force value is greater than the thrust value, the milling head 1 moves upward to reduce the milling amount and continue to maintain a balanced state; when the reaction force value is less than the thrust value, the milling head 1 extends downward to increase the milling amount until dynamic equilibrium is reached, ensuring that the thrust value always remains constant.

[0019] Depending on the material to be milled, different internal cavity pressures can be obtained by changing the drilling fluid discharge rate and replacing different milling heads 1 (different milling heads 1 have different inner hole end faces 3), ultimately achieving different milling thrust values.

[0020] The limiting mechanism includes a limiting nut 8 threaded onto the outer periphery of the milling head 1 on the left side of the piston 7. An inverted L-shaped limiting retaining ring 9 is threaded onto the top connector 2 on the left side of the limiting nut 8. When the milling head 1 moves downwards, causing the end face of the limiting nut 8 to contact the vertical portion of the limiting retaining ring 9, the movement of the milling head 1 is restricted, preventing it from continuing downwards. When a new drill bit is connected to the top connector 2, the top connector 2 is pressed downwards, causing the limiting nut 8 to separate from the limiting retaining ring 9. The milling head 1 can then descend under the pressure of the internal cavity to perform milling work. When the entire milling head structure needs to be removed, the top connector 2 moves upwards, causing the limiting retaining ring 9 to contact the limiting nut 8, thereby removing the milling head 1 along with the drill bit. By setting up the limiting mechanism, mutual limiting between the milling head 1 and the top connector 2 can be achieved.

[0021] The torque transmission mechanism 4 includes a rib 10 on the outer periphery of the milling head 1. The rib 10 is inserted into a groove 11 on the inner wall of the top connector 2. The rib 10 is provided with a liquid flow hole 5. Since the rib 10 is inserted into the groove 11, the top connector 2 can drive the milling head 1 to rotate together during rotation. At the same time, the milling head 1 can also slide downward along the groove 11 under the action of thrust or its own weight.

[0022] The ribs 10 and slots 11 are evenly arranged in multiple rows to ensure a reliable connection between the milling head 1 and the top connector 2.

[0023] Both the outer periphery and the inner wall of the piston 7 are fitted with seals 12 to prevent drilling fluid from seeping out from the gap between the piston 7 and the outer periphery of the milling head 1 and the inner wall of the top connector 2.

[0024] The specific component structures constituting the downhole hydraulic flexible grinding shoe structure of this utility model will be described one by one below, so as to better understand the technical solution of this utility model:

[0025] Top connector 2:

[0026] 1. The right side is provided with a connecting thread that matches the drill bit for connecting the drill bit;

[0027] 2. A connecting thread is provided on the left outer side, which connects with the limiting retaining ring 9, making the tool a single unit;

[0028] 3. The entire inner bore is provided with a flow-through inner hole for drilling fluid circulation;

[0029] 4. An internal torque transmission mechanism (slot 11) is provided in the middle of the inner hole, which cooperates with the external torque transmission mechanism (protruding rib 10) on the upper part of the milling head 1 to realize torque transmission;

[0030] 5. The left end of the inner hole is provided with a piston movement inner hole to ensure the piston 7 movement is sealed;

[0031] Pistons 7:

[0032] 1. Both the outer circle and the inner hole are equipped with sealing elements 12, which cooperate with the corresponding surfaces of the top connector 2 and the milling head 1 to convert the internal pressure into axial thrust, which is then applied to the end face milling teeth through the milling head 1 to obtain the working thrust value.

[0033] Limit nut 8

[0034] 1. It is connected to the milling head 1 by connecting threads to form a whole, and cooperates with the limit ring 9 to realize tool limit.

[0035] Limiting ring 9

[0036] 1. It is connected to the top connector 2 by connecting threads to form a whole, and cooperates with the limit nut 8 to realize the tool limit.

[0037] Milling head 1

[0038] 1. The left side is equipped with end face milling teeth to realize the milling function of the tool;

[0039] 2. The inner bore is provided with a flow-through inner bore for drilling fluid circulation. A flow-stopping hole 3 is provided on the left side near the end of the inner bore. By utilizing the fluid characteristics, the pressure in the inner cavity is generated. The size of the flow-through inner bore can be selected to obtain different pressures in the inner cavity. For details of the structure of the left end of the milling head 1, please refer to patent CN201310729711.8.

[0040] 3. An external torque transmission mechanism (protruding rib 10) is provided on the right side, which cooperates with the internal torque transmission mechanism (slot 11) in the middle of the inner hole of the top connector 1 to realize torque transmission. The outer circle of the torque transmission mechanism 4 is provided with a liquid flow hole 5 to ensure smooth internal liquid flow.

[0041] 4. A connecting thread is provided in the middle to connect with the limit nut 8, making the tool a whole unit;

[0042] 5. The right end of the middle section is provided with the outer circle for piston movement to ensure the sealing of piston 7 movement.

Claims

1. A downhole hydraulic flexible grinding shoe structure, characterized in that: It includes a milling head (1), which is movably connected to the top connector (2) with their inner holes communicating with each other. The end of the inner hole of the milling head (1) is connected to the outside through the inner hole end face (3). A torque transmission mechanism (4) is provided at the movable connection between the milling head (1) and the top connector (2). A liquid flow hole (5) is provided on the torque transmission mechanism (4). The outer periphery of the milling head (1) on the left side of the torque transmission mechanism (4) and the inner hole of the top connector (2) are both stepped structures. A piston mounting chamber (6) is formed between the adjacent stepped surfaces of the outer periphery of the milling head (1) and the inner hole of the top connector (2). The two ends of the liquid flow hole (5) are connected to the piston mounting chamber (6) and the inner hole of the top connector (2) respectively. A piston (7) is sleeved on the outer periphery of the milling head (1) at the piston mounting chamber (6). The length of the piston (7) is less than the length of the piston mounting chamber (6). A limit mechanism is provided on the milling head (1) and the top connector (2) on the left side of the piston (7).

2. The downhole hydraulic flexible grinding shoe structure according to claim 1, characterized in that: The limiting mechanism includes a limiting nut (8) threaded onto the outer periphery of the milling head (1) on the left side of the piston (7), and a limiting retaining ring (9) with an inverted L-shaped structure threaded onto the top connector (2) on the left side of the limiting nut (8).

3. The downhole hydraulic flexible grinding shoe structure according to claim 1, characterized in that: The torque transmission mechanism (4) includes a rib (10) on the outer periphery of the milling head (1), the rib (10) is inserted into a groove (11) on the inner wall of the top connector (2), and a liquid flow hole (5) is provided on the rib (10).

4. The downhole hydraulic flexible grinding shoe structure according to claim 3, characterized in that: The ribs (10) and slots (11) are evenly arranged in multiple rows.

5. The downhole hydraulic flexible grinding shoe structure according to claim 1, characterized in that: The piston (7) has a seal (12) attached to both its outer circumference and inner bore wall.

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