A dual casing segment milling tool

Abstract

The application provides a double-layer casing section milling tool, which comprises an outer cylinder assembly, an inner-layer casing section milling mechanism and an outer-layer casing section milling mechanism arranged on the side wall of the outer cylinder assembly, a reversing joint arranged in the outer cylinder assembly, the reversing joint being telescopic in the axial direction under the action of pressure and rotating by a fixed angle each time the telescopic operation is performed, a camshaft arranged below the reversing joint, and a plurality of blocks arranged on the camshaft and used for pushing the inner-layer casing section milling mechanism or the outer-layer casing section milling mechanism to be unfolded, wherein the reversing joint rotates by the fixed angle, the blocks of the camshaft are alternately arranged on the inner-layer casing section milling mechanism or the outer-layer casing section milling mechanism, and the inner-layer casing section milling mechanism or the outer-layer casing section milling mechanism is unfolded by the blocks when the reversing joint is telescopic downwards. The application realizes that two adjacent casings are milled by one drilling, and the operation efficiency is improved.

Description

A double-layer sleeve segment milling tool Technical Field

[0001] This invention relates to a double-layer casing section milling tool, belonging to the field of petroleum technology. Background Technology

[0002] As offshore oil and gas fields operate for extended periods, an increasing number of wells are entering a non-productive state. These non-productive wells require immediate abandonment to permanently eliminate their potential environmental threats. The basic requirements for permanent offshore well abandonment include four aspects:

[0003] (1) Seal off and protect all freshwater and near-freshwater layers; (2) Seal off and protect all future producing layers with commercial exploitation value; (3) Prevent fluid from leaking or flowing out of the well; (4) Remove all facilities above the seabed and cut off pipes below the mudline.

[0004] This requires milling off a certain length of casing and then cementing the exposed formation to seal the production layer and prevent oil and gas leaks. In some cases, it is necessary to mill off two layers of casing before cementing. Conventional casing milling technology requires milling off two layers of casing from the inside out. For example, when milling off two layers of casing, 9-5 / 8” × 13-3 / 8”, the milling tool is run down into the 9-5 / 8” casing to the target depth, extending a short blade to mill off a certain length of the 9-5 / 8” casing; then, the drill is pulled back to the wellhead to switch to a milling tool with a long blade, and then it is run down into the 9-5 / 8” casing to the predetermined depth, extending the long blade to mill off a certain length of the 13-3 / 8” casing. This requires multiple trips up and down, resulting in low operational efficiency. Summary of the Invention

[0005] To address the aforementioned technical problems in the existing technology, this invention proposes a double-layer casing section milling tool that can control the extension of different cutter wings to achieve milling of two adjacent casing layers in one pass, resulting in high work efficiency.

[0006] This invention proposes a double-layer sleeve segment milling tool, comprising:

[0007] An outer cylinder assembly, wherein an deployable inner sleeve segment milling mechanism and an outer sleeve segment milling mechanism are provided on the side wall of the outer cylinder assembly;

[0008] The reversing joint installed inside the outer cylinder assembly extends and retracts axially downward under pressure, and rotates by a fixed angle with each extension and retraction.

[0009] A camshaft located below the reversing joint is provided with several blocks on the camshaft that push the inner sleeve section milling mechanism or the outer sleeve section milling mechanism to unfold.

[0010] When the reversing joint rotates at the fixed angle, it drives the stop of the camshaft to act alternately on the inner sleeve section milling mechanism or the outer sleeve section milling mechanism; when the reversing joint extends downward, it drives the inner sleeve section milling mechanism or the outer sleeve section milling mechanism to unfold through the stop.

[0011] A further improvement of the present invention is that a pressure regulating device is provided above the reversing joint, and the pressure regulating device pushes the reversing joint downward under the action of fluid pressure;

[0012] A reset mechanism is provided between the reversing joint and the outer cylinder assembly to provide an upward thrust to the reversing joint.

[0013] A further improvement of the present invention is that the outer cylinder assembly includes a bypass connector for mounting the reversing joint, the lower end of the bypass connector is connected to a lower cavity connector for mounting the camshaft, the lower end of the lower cavity connector is provided with a fixed wing stabilizer, and the upper end of the bypass connector is provided with an upper connector.

[0014] A further improvement of the present invention is that the reversing joint includes an upper reversing joint cap and a lower reversing joint rod, and the lower end face of the reversing joint cap forms an annular upper shoulder.

[0015] The inner wall of the bypass connector is provided with an upward-facing lower shoulder, and the reset mechanism is installed in the annular space between the upper shoulder and the lower shoulder.

[0016] A further improvement of the present invention is that the reset mechanism includes a thrust bearing and a spring.

[0017] A further improvement of the present invention is that a set screw is provided inside the bypass connector, and a limiting groove is provided on the outer wall of the reversing connector cap; the set screw is limited within the limiting groove.

[0018] When the reversing joint extends or retracts axially, the limiting groove slides relative to the set screw, causing the reversing joint to rotate at a fixed angle.

[0019] A further improvement of the present invention is that the limiting groove includes an upper groove section and a lower groove section arranged along the axial direction, the upper groove section and the lower groove section are located at different axial positions and are arranged at intervals, and the upper groove section is connected to two adjacent lower groove sections by a first inclined groove section and a second inclined groove section respectively;

[0020] When the reversing joint extends downward, the set screw slides out in the lower groove section and enters the upper groove section through the first inclined groove section; when the reversing joint retracts upward, the set screw slides out in the upper groove section and enters another lower groove section through the second inclined groove section.

[0021] A further improvement of the present invention is that the upper end of the upper groove section is the upper dead point of the set screw, and the lower end of the lower groove section is the lower dead point of the set screw.

[0022] The two endpoints where the first inclined trough segment and the second inclined trough segment intersect are the first turning point and the second turning point, respectively. The first turning point corresponds to the lower trough segment and is deflected at a certain angle; the second turning point corresponds to the upper trough segment and is deflected at a certain angle.

[0023] A further improvement of the present invention is that the inner sleeve segment milling mechanism includes a short blade hinged to the lower part of the lower cavity joint, the short blade rotating along the hinge axis under the push of the stop block and thus unfolding in the radial direction of the outer cylinder assembly.

[0024] A further improvement of the present invention is that the outer sleeve segment milling mechanism includes a long blade hinged to the upper part of the lower cavity joint and a straightening short blade hinged to the middle part of the lower cavity joint. The long blade and the straightening short blade are pushed by the stop block to rotate along the hinge axis and thus unfold in the radial direction of the outer cylinder assembly.

[0025] A further improvement of the present invention is that the stop block includes a first stop block evenly distributed circumferentially on the upper part of the camshaft, a second stop block evenly distributed circumferentially on the middle part of the camshaft, and a third stop block evenly distributed circumferentially on the lower part of the camshaft.

[0026] The first stop pushes the long blade wing to unfold, the second stop pushes the straightening short blade wing to unfold, and the third stop pushes the short blade wing to unfold.

[0027] A further improvement of the present invention is that the first stop and the second stop are in the same circumferential position, and the third stop differs from the first stop and the second set of stop in circumferential position by a fixed angle.

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] The present invention discloses a double-layer casing section milling tool, which can control the extension of different cutter wings to achieve milling of two adjacent casing layers in one pass, resulting in high work efficiency. Attached Figure Description

[0030] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0031] Figure 1 shows a schematic diagram of the structure of a double-layer sleeve segment milling tool according to an embodiment of the present invention;

[0032] Figure 2 shows a schematic diagram of the working state of a double-layer sleeve segment milling tool according to an embodiment of the present invention, illustrating the state when cutting the inner sleeve.

[0033] Figure 3 shows a schematic diagram of the working state of a double-layer sleeve segment milling tool according to an embodiment of the present invention, illustrating the state when cutting the outer sleeve.

[0034] Figure 4 shows a schematic diagram of the reversing connector according to an embodiment of the present invention;

[0035] Figure 5 shows a schematic diagram of the camshaft structure according to an embodiment of the present invention;

[0036] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale.

[0037] The meanings of the reference numerals in the attached drawings are as follows: 1. Outer cylinder assembly; 2. Reversing joint; 3. Camshaft; 11. Bypass joint; 12. Lower cavity joint; 13. Upper joint; 14. Fixed wing stabilizer; 111. Lower shoulder; 112. Set screw; 121. Long blade; 122. Stabilizing short blade; 123. Short blade; 21. Reversing joint cap; 22. Reversing joint rod; 23. Pressure regulating device; 24. Reset mechanism; 25. Upper shoulder; 211. Limiting groove; 212. Upper groove section; 213. Lower groove section; 214. First inclined groove section; 215. Second inclined groove section; 216. Top dead center; 217. Bottom dead center; 218. First turning point; 219. Second turning point; 241. Thrust bearing. 242. Spring; 31. First stop block; 32. Second stop block.

[0038] 33. The third stop.

[0039] 34. Nozzle. Detailed Implementation

[0040] To make the technical solutions and advantages of the present invention clearer, exemplary embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. Furthermore, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0041] Figure 1 schematically shows a double-layer sleeve segment milling tool according to an embodiment of the present invention, including an outer cylinder assembly 1. An deployable inner sleeve segment milling mechanism and an outer sleeve segment milling mechanism are disposed on the side wall of the outer cylinder assembly 1. The inner sleeve segment milling mechanism is used to mill the inner sleeve, and the outer sleeve segment milling mechanism is used to mill the outer sleeve. A reversing joint 2 is disposed inside the outer cylinder assembly 1. The reversing joint 2 extends and retracts axially downward under pressure, and rotates by a fixed angle with each extension and retraction. This fixed angle can be 30-60 degrees, or other angles can be selected according to actual conditions. A camshaft 3 is disposed below the reversing joint 2, and the camshaft 3 is provided with several stops that push the inner or outer sleeve segment milling mechanism to unfold.

[0042] When using the double-layer casing segment milling tool according to this embodiment, under the action of fluid pressure, the reversing joint 2 extends, retracts, and rotates, driving the camshaft 3 to extend, retract, and rotate. When the camshaft 3 extends downward, the stop block drives the inner casing segment milling mechanism or the outer casing segment milling mechanism to start and unfold. In this embodiment, when the reversing joint 2 rotates at the fixed angle, it drives the stop block of the camshaft 3 to alternately act on the inner casing segment milling mechanism or the outer casing segment milling mechanism. The stops acting on the inner casing segment milling mechanism and the outer casing segment milling mechanism are different, and there is a fixed angular deviation between them in the circumferential direction.

[0043] In the initial state, the reversing joint 2 is in a retracted state, as are the inner and outer sleeve section milling mechanisms. When the reversing joint 2 extends downward under the action of fluid pressure, the camshaft 3 extends accordingly, and the stop pushes the inner sleeve section milling mechanism to unfold, at which point the inner sleeve can be milled (as shown in Figure 4).

[0044] When the fluid pressure decreases, the reversing joint 2 retracts upward, and the camshaft 3 also retracts accordingly. The stop block moves away from the inner sleeve section milling mechanism, causing the inner sleeve section milling mechanism to retract. During the retraction of the reversing joint 2, the reversing joint 2 drives the camshaft 3 to rotate by a fixed angle, so that the stop block acting on the outer sleeve section milling mechanism during the next extension can push the outer sleeve section milling mechanism to unfold (as shown in Figure 3).

[0045] When the fluid pressure increases again, it pushes the reversing joint 2 to extend downward, and the camshaft 3 extends accordingly. The stop block pushes the outer sleeve section milling mechanism to unfold, at which point the outer sleeve can be milled.

[0046] When the fluid pressure decreases, the reversing joint 2 retracts upward, and the camshaft 3 also retracts accordingly. The stop block moves away from the outer sleeve section milling mechanism, causing the outer sleeve section milling mechanism to retract. During the retraction of the reversing joint 2, the reversing joint 2 drives the camshaft 3 to rotate by a fixed angle, so that the stop block acting on the inner sleeve section milling mechanism can push the inner sleeve section milling mechanism to unfold when it extends again.

[0047] According to the double-layer casing segment milling tool described in this embodiment, segment milling of double-layer casing can be performed in one drilling pass.

[0048] In one embodiment, as shown in Figure 1, a pressure regulating device 23 is provided above the reversing joint 2. The pressure regulating device 23 pushes the reversing joint 2 downward under the action of fluid pressure. A reset mechanism 24 is provided between the reversing joint 2 and the outer cylinder assembly 1 to provide an upward thrust to the reversing joint 2.

[0049] In this embodiment, the pressure regulating device 23 receives the fluid pressure from above. When the fluid pressure increases, it can move downward, thereby driving the reversing joint 2 to move downward. When the fluid pressure decreases, under the pushing action of the reset mechanism 24, the reversing joint 2 moves upward to its original position. This completes one extension and retraction process, thereby alternately activating the inner sleeve section milling mechanism and the outer sleeve section milling mechanism to mill the inner sleeve or the outer sleeve.

[0050] In a preferred embodiment, the pressure regulating device 23 includes a conical straightening mechanism at the upper end and a disc-shaped structure at the lower end, which engages with the step between the bypass connector 11 and the upper connector 13. The disc-shaped structure has several flow holes on its side for fluid flow. The lower end is connected to the upper end of the reversing structure.

[0051] In one embodiment, the outer cylinder assembly 1 includes, from top to bottom, an upper connector 13, a bypass connector 11, a lower cavity connector 12, and a fixed-wing centralizer 14. A reversing connector 2 is installed inside the bypass connector 11, allowing it to extend and retract axially. A camshaft 3 is installed inside the lower cavity connector 12, allowing it to extend and retract axially. The inner sleeve section milling mechanism and the outer sleeve section milling mechanism are also installed on the side wall of the lower cavity connector 12.

[0052] In one embodiment, as shown in FIG4, the reversing connector 2 includes an upper reversing connector cap 21 and a lower reversing connector rod 22. The lower end face of the reversing connector cap 21 forms an annular upper shoulder 25. An upward-facing lower shoulder 111 is provided on the inner wall of the bypass connector 11, and the reset mechanism 24 is installed in the annular space between the upper shoulder 25 and the lower shoulder 111.

[0053] Preferably, the reset mechanism 24 includes a thrust bearing 241 and a spring 242.

[0054] In the double-layer sleeve section milling tool according to this embodiment, the spring 242 is installed between the upper shoulder 25 and the lower shoulder 111, with the upper end fixed on the upper shoulder 25 and the lower end fixed on the lower shoulder 111. When the fluid pressure increases, the spring 242 is pushed to compress, and when the fluid pressure decreases, the spring 242 pushes the reversing joint 2 to reset.

[0055] In a preferred embodiment, the upper connector 13 and the bypass connector 11 are connected by threads; the pressure regulating device 23 and the reversing connector 2 are connected by threads (preferably, the tightening of the threads is in the same direction as the rotation of the reversing connector 2 to avoid loosening); the reversing connector 2 and the camshaft 3 are connected by threads. A hexagonal socket head cap set screw 112 is threaded onto the bypass connector 11, and the reversing connector 2 uses a Y-type sealing ring to ensure a tight seal between itself and the bypass connector 11.

[0056] The thrust ball bearing and spring 242 are mounted on the reversing joint rod 22 of the reversing joint 2, and the axial movement is restricted by the upper shoulder 25 and lower shoulder 111 of the reversing joint 2 and the bypass joint 11.

[0057] The bypass connector 11 and the lower cavity connector 12 are connected by threads; the lower cavity connector 12 and the fixed wing centralizer 14 are connected by threads; the nozzle is fixed inside the camshaft 3 by an elastic retaining ring.

[0058] In one embodiment, a set screw 112 is provided inside the bypass connector 11. The set screw 112 is preferably a socket head cap screw 112 with its end extending into the interior of the bypass connector 11. A limiting groove 211 is provided on the outer wall of the reversing connector cap 21; the set screw 112 is limited within the limiting groove 211.

[0059] When the reversing joint 2 extends or retracts axially, the limiting groove slides relative to the set screw 112, causing the reversing joint 2 to rotate at a fixed angle.

[0060] In one embodiment, as shown in FIG4, the limiting groove 211 includes an upper groove section 212 and a lower groove section 213 arranged along the axial direction. The upper groove section 212 and the lower groove section 213 are located at different axial positions and are arranged at intervals. The upper groove section 212 connects two adjacent lower groove sections 213 through a first inclined groove section 214 and a second inclined groove section 215, respectively.

[0061] When the reversing joint 2 extends downward, the set screw 112 slides out in the lower groove section 213 and enters the upper groove section 212 through the first inclined groove section 214; when the reversing joint 2 retracts upward, the set screw 112 slides out in the upper groove section 212 and enters another lower groove section 213 through the second inclined groove section 215.

[0062] The angle generated by the circumferential distance between the upper groove sections 212 is the fixed angle, and the angle generated by the circumferential distance between the lower groove sections 213 is also the fixed angle. After the reversing joint 2 completes one extension and retraction, it passes through the lower groove section 213, the first inclined groove section 214, the upper groove section 212, and the second inclined groove section 215, finally returning to the next lower groove section 213, causing the reversing joint 2 to complete one rotation, with the rotation angle being the fixed angle. This drives the camshaft 3 to rotate, causing the stop block to align with the inner or outer sleeve section milling mechanism, thereby controlling and adjusting the deployment of the inner or outer sleeve section milling mechanism.

[0063] In a preferred embodiment, the upper end of the upper groove section 212 defines the upper dead point 216 of the set screw 112, and the lower end of the lower groove section 213 defines the lower dead point 217 of the set screw 112; during the extension and retraction of the reversing joint 2, the set screw 112 can be locked on the upper dead point 216 or the lower dead point 217 to determine the maximum displacement of the extension and retraction of the reversing joint 2.

[0064] The two endpoints where the first inclined groove segment 214 and the second inclined groove segment 215 intersect are the first turning point 218 and the second turning point 219, respectively. The first turning point 218 corresponds to the lower groove segment 213 and is deflected at a certain angle; the second turning point 219 corresponds to the upper groove segment 212 and is deflected at a certain angle.

[0065] In the double-layer sleeve section milling tool according to this embodiment, the apex of the sharp angle formed by the intersection of the upper edges of the first inclined groove section 214 and the second inclined groove section 215 is the first turning point 218. The sharp angle of the first turning point 218 points downwards, is located above the lower groove section 213, and is slightly inclined to one side of the first inclined groove section 214. This ensures that the set screw 112 sliding out of the first inclined groove section 214 can smoothly enter the lower groove section 213, and also ensures that the set screw 112 sliding out of the lower groove section 213 can enter the second inclined groove section 215.

[0066] The tip of the sharp angle formed by the intersection of the lower edges of the first inclined groove section 214 and the second inclined groove section 215 is the second turning point 219. The sharp angle of the second turning point 219 points upward, is located below the upper groove section 212, and is slightly inclined to one side of the second inclined groove section 215. This ensures that the set screw 112 sliding out of the second inclined groove section 215 can smoothly enter the upper groove section 212, and also ensures that the set screw 112 sliding out of the upper groove section 212 can enter the first inclined groove section 214.

[0067] This ensures that the reversing joint 2 rotates in one direction throughout the entire process, avoiding the reciprocating rotation in two directions during the extension or retraction process.

[0068] In one embodiment, the inner sleeve segment milling mechanism includes a short blade 123 hinged to the lower part of the lower cavity connector 12, the short blade 123 rotating along the hinge axis under the push of the stop block to unfold in the radial direction of the outer cylinder assembly 1.

[0069] In this embodiment, the lower cavity connector 12 has a radially opening groove at its lower part, and the short blade 123 is disposed in the groove. The tip of the short blade 123 points downward, and its upper end is hinged to the lower cavity connector 12. It also has an inwardly extending support leg that can cooperate with the third stop 33. When the third stop 33 moves downward, it pushes the support leg downward, causing the short blade 123 to rotate along the hinge axis, and the lower blade tip unfolds outward, as shown in Figure 4. The unfolded short blade 123 can cut the inner sleeve.

[0070] In one embodiment, the outer sleeve segment milling mechanism includes a long blade 121 hinged to the upper part of the lower cavity joint 12 and a straightening short blade 122 hinged to the middle part of the lower cavity joint 12. The long blade 121 and the straightening short blade 122 rotate along the hinge axis under the push of the stop block, thereby unfolding in the radial direction of the outer cylinder assembly 1.

[0071] In this embodiment, slots are provided in the middle and upper parts of the lower cavity connector 12 for mounting the long blade 121 and the straightening short blade 122, respectively. The structure and installation method of the long blade 121 and the straightening short blade 122 are the same as those of the short blade 123. Both have the blade tip pointing downwards, the upper end hinged to the lower cavity connector 12, and a support leg extending inwards. The support leg of the long blade 121 can cooperate with the first stop block 31, and the support leg of the straightening short blade 122 can cooperate with the second stop block 32. When the first stop block 31 and the second stop block 32 move downwards, they push the support leg downwards, causing the straightening short blade 122 and the long blade 121 to rotate along the hinge axis. The lower blade tip unfolds outwards, as shown in Figure 5. The unfolded short blade 123 can cut the inner sleeve.

[0072] The tips of the short blade 123 and the long blade 121 are sharp, while the tip of the straightening short blade 122 is flat. During the cutting of the outer sleeve, the straightening short blade 122 can support the inner sleeve, providing support for the long blade 121 to mill the outer sleeve.

[0073] In one embodiment, as shown in FIG5, the stop blocks include a first stop block 31 evenly distributed circumferentially on the upper part of the camshaft 3, a second stop block 32 evenly distributed circumferentially on the middle part of the camshaft 3, and a third stop block 33 evenly distributed circumferentially on the lower part of the camshaft 3. The first stop block 31 pushes the long blade 121 to unfold, the second stop block 32 pushes the straightening short blade 122 to unfold, and the third stop block 33 pushes the short blade 123 to unfold.

[0074] In one embodiment, the three slots on the lower cavity connector 12 for mounting the long blade 121, the short blade 123, and the straightening short blade 122 are all located at the same circumferential angle.

[0075] The first stop block 31 and the second stop block 32 are in the same circumferential position, and the third stop block 33 is circumferentially different from the first stop block 31 and the second stop block 32 by a fixed angle.

[0076] Preferably, alloy blocks are welded to the ends of the short blade 123, the straightening short blade 122, and the long blade 121. The short blade 123, the straightening short blade 122, and the long blade 121 are mounted on the lower cavity connector 12 via pins, evenly distributed circumferentially, with a preferred number of 3-5 per group; this embodiment uses 3. The third stop 33 is circumferentially offset from the first stop 31 or the second stop 32 by a 60-degree angle. The fixed angle is 120 degrees.

[0077] In the double-casing section milling tool according to this embodiment, the operation process is as follows: Drilling fluid enters the tool through the upper connector 13 and acts on the pressure regulating device 23. By adjusting the drilling fluid discharge rate, the pressure on the pressure regulating device 23 is controlled. Gradually increasing the drilling fluid pressure pushes the reversing connector 2 and camshaft 3 downwards, and the set screw 112 moves upwards from the bottom dead center 217 of the lower groove section 213 of the reversing connector 2, passes through the first inclined groove, enters the next upper groove section 212, and finally reaches the top dead center 216, at which point the spring 242 is compressed. The third stop 33 presses against the tail support of the short blade 123 and pushes the short blade 123 out. The short blade 123 unfolds radially to begin milling the inner casing (as shown in Figure 2).

[0078] After the inner casing is milled off, the control pressure regulating device 23 gradually reduces the drilling fluid pressure. The spring 242 pushes the reversing joint 2 to reset, and the set screw 112 leaves the top dead center 216 of the reversing joint 2, slides out through the upper groove section 212, and enters the lower groove section 213 through the second inclined groove, finally locking at the bottom dead center 217. During this process, the camshaft 3 stop block leaves the support foot at the tail of the short cutter wing 123, and the short cutter wing 123 retracts (as shown in Figure 1). During the milling process, the alloy block of the short cutter wing 123 wears down, and the tail support foot of the short cutter wing 123 is limited by the structure of the camshaft 3 shaft and the lower cavity joint 12. Therefore, the short cutter wing 123 rotates slightly around the pin shaft and will not affect the next operation.

[0079] The control pressure regulating device 23 gradually increases the drilling fluid pressure, pushing the reversing joint 2 and camshaft 3 downwards. The set screw 112 moves upwards again from the bottom dead center 217 of the lower groove section 213 of the reversing joint 2, passes through the first inclined groove, enters the upper groove section 212, and finally reaches the top dead center 216. At this time, the spring 242 is compressed. The first stop block 31 abuts against the tail support of the long cutter wing 121, and the second stop block 32 abuts against the right angle of the straightening short cutter wing 122, pushing out the long cutter wing 121 and the straightening short cutter wing 122. The straightening short cutter wing 122 is supported on the inner casing, and the long cutter wing 121 unfolds radially to begin milling the inner casing (as shown in Figure 3).

[0080] After the outer casing is milled off, the control pressure regulating device 23 gradually reduces the drilling fluid pressure. Spring 242 pushes the reversing joint 2 to reset, and the set screw 112 moves away from the top dead center 216 of the reversing joint 2, slides out through the upper groove section 212, passes through the second inclined groove, and enters the lower groove section 213, finally locking at the bottom dead center 217. During this process, the first stop 31 and the second stop 32 of the camshaft 3 move away from the support feet at the tail of the long cutter wing 121 and the straightening short cutter wing 122, respectively, causing the long cutter wing 121 and the straightening short cutter wing 122 to retract (as shown in Figure 1). This completes one round of milling operation for the double casing section.

[0081] In this invention, "upper" refers to the direction closer to the wellhead, and "lower" refers to the direction farther from the wellhead.

[0082] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and / or modifications falling within the scope of the invention, and all changes and / or modifications made according to embodiments of the invention should be covered within the protection scope of the invention.

Claims

1. A double-layer sleeve segment milling tool, characterized in that, include: An outer cylinder assembly (1) is provided with an expandable inner sleeve section milling mechanism and an outer sleeve section milling mechanism on its side wall; a reversing joint (2) is provided inside the outer cylinder assembly (1), which extends and retracts axially downward under pressure, and rotates by a fixed angle each time it extends and retracts; a camshaft (3) is provided below the reversing joint (2), and the camshaft (3) is provided with several stops that push the inner sleeve section milling mechanism or the outer sleeve section milling mechanism to unfold; wherein, when the reversing joint (2) rotates at the fixed angle, it carries... The stop block of the camshaft (3) alternately acts on the inner sleeve section milling mechanism or the outer sleeve section milling mechanism; when the reversing joint (2) extends downward, it drives the inner sleeve section milling mechanism or the outer sleeve section milling mechanism to unfold through the stop block; a pressure regulating device (23) is provided above the reversing joint (2), and the pressure regulating device (23) pushes the reversing joint (2) to extend downward under the action of fluid pressure; a reset mechanism (24) is provided between the reversing joint (2) and the outer cylinder assembly (1) to provide an upward thrust for the reversing joint (2); The outer cylinder assembly (1) includes a bypass connector (11) for mounting the reversing connector (2), the lower end of the bypass connector (11) is connected to a lower cavity connector (12) for mounting the camshaft (3), the lower end of the lower cavity connector (12) is provided with a fixed wing stabilizer (14), and the upper end of the bypass connector (11) is provided with an upper connector (13); the reversing connector (2) includes an upper reversing connector cap (21) and a lower reversing connector rod (22), the... The lower end face of the reversing connector cap (21) forms an annular upper shoulder (25); an upward-facing lower shoulder (111) is provided on the inner wall of the bypass connector (11), and the reset mechanism (24) is installed in the annular space between the upper shoulder (25) and the lower shoulder (111); a set screw (112) is provided inside the bypass connector (11), and a limiting groove (211) is provided on the outer wall of the reversing connector cap (21); the set screw (112) limits the space between the upper shoulder (25) and the lower shoulder (111). Within the limiting groove (211); when the reversing joint (2) extends and retracts axially, the limiting groove (211) slides relative to the set screw (112), causing the reversing joint (2) to rotate at a fixed angle; the limiting groove (211) includes an upper groove section (212) and a lower groove section (213) arranged axially, the upper groove section (212) and the lower groove section (213) are located at different axial positions and are arranged at intervals, the upper groove section (212) is respectively connected to the first inclined groove section ( 214) and the second inclined groove section (215) connect two adjacent lower groove sections (213); when the reversing joint (2) extends downward, the set screw (112) slides out in the lower groove section (213) and enters the upper groove section (212) through the first inclined groove section (214); when the reversing joint (2) retracts upward, the set screw (112) slides out in the upper groove section (212) and enters another lower groove section (213) through the second inclined groove section (215).

2. The double-layer sleeve segment milling tool according to claim 1, characterized in that, The reset mechanism (24) includes a thrust bearing (241) and a spring (242).

3. The double-layer sleeve segment milling tool according to claim 2, characterized in that, The upper end of the upper groove section (212) is the upper dead point (216) of the set screw (112), and the lower end of the lower groove section (213) is the lower dead point (217) of the set screw (112). The two endpoints of the intersection of the first inclined groove section (214) and the second inclined groove section (215) are the first turning point (218) and the second turning point (219), respectively. The first turning point (218) corresponds to the lower groove section (213) and is deflected at a certain angle. The second turning point (219) corresponds to the upper groove section (212) and is deflected at a certain angle.

4. The double-layer sleeve segment milling tool according to claim 3, characterized in that, The inner sleeve segment milling mechanism includes a short blade (123) hinged to the lower part of the lower cavity connector (12), which rotates along the hinge axis under the push of the stop block and thus unfolds in the radial direction of the outer cylinder assembly (1).

5. The double-layer sleeve segment milling tool according to claim 4, characterized in that, The outer sleeve segment milling mechanism includes a long blade (121) hinged to the upper part of the lower cavity joint (12) and a straightening short blade (122) hinged to the middle part of the lower cavity joint (12). The long blade (121) and the straightening short blade (122) rotate along the hinge axis under the push of the stop block, thereby unfolding in the radial direction of the outer cylinder assembly (1).

6. The double-layer sleeve segment milling tool according to claim 5, characterized in that, The stop blocks include a first stop block (31) evenly distributed circumferentially on the upper part of the camshaft (3), a second stop block (32) evenly distributed circumferentially on the middle part of the camshaft (3), and a third stop block (33) evenly distributed circumferentially on the lower part of the camshaft (3); wherein, the first stop block (31) pushes the long blade (121) to unfold, the second stop block (32) pushes the straightening short blade (122) to unfold, and the third stop block (33) pushes the short blade (123) to unfold.

7. The double-layer sleeve segment milling tool according to claim 6, characterized in that, The first stop (31) and the second stop (32) are in the same circumferential position, and the third stop (33) is in a circumferential position that differs from the first stop (31) and the second stop (32) by a fixed angle.

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