Downhole Electric Milling Tool for Casing Damage

Abstract

The present invention relates to a downhole electric casing milling tool for casing milling. It consists of a housing, a hydraulic anchoring assembly, and a milling booster assembly. The upper end cover is threadedly connected to the positioning sleeve, with a clearance left in the middle for mating with a cable, and the downhole tool is vertically hoisted. The hydraulic anchoring assembly includes a motor, an axial piston pump, and an anchoring cylinder. The milling booster assembly is composed of a hollow shaft motor, a spline motor, a lower housing, a ball screw, a spline rotating shaft, a positioning block, and a milling head. The structure of the present invention is reliable, capable of meeting the requirements of complex downhole milling operation conditions, and improving the milling efficiency of downhole casings.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil drilling equipment, and relates to a downhole electric milling tool for casing wear cutting. Background Art

[0002] To meet the needs of workover operations, drilling and milling tools are developing towards fast and efficient performance. Improvements have been made from the material of the cutting and milling elements to the layout structure to develop efficient milling tools. Coupled with the use of downhole motor drills and new hydraulic boosters and other tools, the drilling and milling method will be an important and effective treatment method in future workover operations.

[0003] Electric milling technology is a new type of milling technology that combines machinery, hydraulics, hydraulic fracturing, and downhole electric milling, greatly improving the construction efficiency of casing wear milling and reducing the construction cost. With the development and popularization of efficient milling tools and the matching of new downhole motor drills, the future workover market will replace the history of simply using large-load lifting methods to salvage large-diameter downhole tools. This invention is of great significance for promoting the development of new milling technologies. Summary of the Invention

[0004] The purpose of the present invention is to optimize the casing milling method to improve the milling efficiency, reduce the operation cost of drilling and milling, and support new downhole motor drills.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The downhole electric milling tool for casing wear of the present invention mainly consists of a housing, a hydraulic anchoring component, and a milling booster component; the upper end cover is threadedly connected to the positioning sleeve, with a clearance left in the middle for cable fitting, and the downhole tool is vertically hoisted; the hydraulic anchoring component is composed of a motor, an oil storage chamber, a plunger pump, an oil circuit component, an anchoring cylinder, an upper housing, an anchoring plate, a support frame, a spring, an elastic plate, a cable tube, and a limit block; the upper housing is threadedly connected to the positioning sleeve, and the lower external thread is threadedly connected to the upper internal thread of the middle housing; the motor in the inner cavity is connected to the plunger pump through a coupling; the lower part of the plunger pump is threadedly connected to the upper part of the cable hole of the oil circuit component; the plunger pump is circumferentially fixed to the oil storage chamber, and the oil suction hole is coaxially limited with the oil storage chamber hole. The anchoring plate and the support frame are bolted to the lower part of the anchoring cylinder, and the spring limits the anchoring cylinder to realize the return stroke of the anchoring cylinder during pressure relief. The external thread of the limit block is threadedly connected to the lower internal thread of the lower housing; the milling booster component is composed of a hollow shaft motor, a spline motor, a lower housing, a ball screw, a spline rotating shaft, a positioning block, and a milling head; the hollow shaft motor is fixedly connected to the limit block by screws, the spline motor is fixedly connected to the lower housing by screws, the spline motor is spline-connected to the spline rotating shaft, the ball screw axially fixes the spline rotating shaft, the lower part of the spline rotating shaft is in interference fit with the bearing of the ball screw, and the internal thread of the milling head is threadedly connected to the external thread of the spline rotating shaft.

[0007] For the downhole electric milling tool for casing damage in the above solution, the upper housing of the hydraulic anchoring assembly is provided with an oil suction hole, a throttle valve groove, and a cable tube; the oil circuit component is provided with an oil drain hole, an oil inlet hole, and a cable hole; the oil storage chamber stores hydraulic oil from the oil suction hole, and the plunger pump sucks oil from the oil storage chamber and then pumps the high-pressure oil into the oil inlet hole to the sealed inner cavity above the anchoring cylinder and the middle housing, pushing the anchoring cylinder to axially tension the anchoring mechanism.

[0008] For the downhole electric milling tool for casing damage in the above solution, the hollow shaft motor rotates to drive the nut of the ball screw to move axially downward, transmitting axial pressure to the milling head; the spline motor rotates to drive the spline rotating shaft to rotate, and cooperates with the rotation and axial movement of the milling head to couple for downhole milling of casing damage.

[0009] Compared with the prior art, the beneficial effects of the present invention are:

[0010] (1) The anchoring structure of this tool has strong hydraulic anchoring ability, ensuring the stability of the milling working condition and ensuring good milling effect;

[0011] (2) This tool can ensure the smooth transmission of the drilling pressure and torque to the drill bit without energy transfer loss;

[0012] (3) This tool has a simple structure, is suitable for various working conditions, and further reduces the operation cost. Description of the Drawings

[0013] Figure 1 is a schematic structural diagram of the downhole electric milling tool for casing damage of the present invention;

[0014] Figure 2 is a schematic structural diagram of the upper housing of the present invention;

[0015] Figure 3 is a schematic cross-sectional view of the oil circuit component of the present invention;

[0016] Figure 4 is a schematic structural diagram of the anchoring cylinder of the present invention;

[0017] Figure 5 is a schematic structural diagram of the anchoring plate of the present invention;

[0018] Figure 6 is a schematic structural diagram of the spline rotating shaft of the present invention

[0019] In the figure: 1. Cable; 2. Upper end cover; 3. Positioning sleeve; 4. Upper housing, 4a Oil suction hole, 4b Throttle valve groove, 4c Cable pipe; 5. Motor; 6. Coupling; 7. Oil storage chamber; 8. Plunger pump; 9. Oil circuit component, 9a Oil drain hole, 9b Oil inlet hole, 9c Cable hole; 10. Middle housing; 11. Cable sleeve; 12. Hydraulic cylinder; 13. Anchoring plate, 13a Fastening groove; 14. Anchoring support frame; 15. Spring; 16. Elastic plate; 17. Limit block; 18. Hollow shaft motor; 19. Ball screw; 20. Lower housing; 21. Spline motor; 22. Spline rotating shaft; 23. Nut; 24. Positioning block; 25. Milling head. Detailed implementation manner

[0020] The present invention will be further described below in conjunction with the accompanying drawings and the detailed implementation manner:

[0021] Referring to Figure 1, the downhole electric milling tool for casing damage of the present invention mainly consists of a housing, a hydraulic anchoring assembly, and a milling and boosting assembly.

[0022] The upper end cover 2 is threadedly connected to the positioning sleeve 3, with a clearance left in the middle to fit the cable 1, and the downhole tool is vertically hoisted. The hydraulic anchoring assembly is composed of a motor 5, an oil storage chamber 7, a plunger pump 8, an oil circuit component 9, an anchoring cylinder 12, an upper housing 4, an anchoring plate 13, a support frame 14, a spring 15, an elastic plate 16, a cable pipe 11, and a limit block 17. The upper housing 4 is threadedly connected to the positioning sleeve 3, and the lower external thread is connected to the upper internal thread of the middle housing 10. The inner cavity motor 5 is connected to the plunger pump 8 through a coupling 6. The lower part of the plunger pump 8 is threadedly connected to the upper part of the cable hole 9c of the oil circuit component 9. The plunger pump 8 is circumferentially fixed to the oil storage chamber 7, and the oil suction hole 4a is coaxially limited with the oil storage chamber hole. The anchoring plate 13 and the support frame 14 are bolted to the lower part of the anchoring cylinder 12. The spring 15 limits the anchoring cylinder 12 and enables the anchoring cylinder 12 to return during pressure relief. The external thread of the limit block 17 is connected to the lower internal thread of the lower housing body 20. The milling and boosting assembly is composed of a hollow shaft motor 18, a spline motor 21, a lower housing 20, a ball screw 19, a spline rotating shaft 22, a positioning block 24, and a milling head 25. The hollow shaft motor 18 is fixedly connected to the limit block by screws. The spline motor 21 is screwed to the lower housing 20. The spline motor 21 is spline-connected to the spline rotating shaft 22. The ball screw 19 axially fixes the spline rotating shaft 22. The lower part of the spline rotating shaft 22 is in interference fit with the bearing of the ball screw 19. The inner thread of the milling head 25 is connected to the external thread of the spline rotating shaft 22.

[0023] As shown in Figures 2 and 3, the upper housing 4 of the hydraulic anchoring assembly is provided with an oil suction hole 4a, a throttle valve groove 4b, and a cable tube 4c; the oil circuit component 9 is provided with an oil discharge hole 9a, an oil inlet hole 9b, and a cable hole 9c; the oil storage chamber 7 stores hydraulic oil from the oil suction hole 4a, and the plunger pump 8 sucks oil from the oil storage chamber 7 and then pumps the high-pressure oil into the oil inlet hole 9b to the upper sealed inner cavity of the anchoring cylinder 12 and the middle housing 10, pushing the axial anchoring mechanism of the anchoring cylinder 12 to be tensioned.

[0024] As shown in the attached Figure 6 figure, the hollow shaft motor 18 rotates to drive the nut 23 of the ball screw 19 to move axially downward, transmitting axial pressure to the mill bit 25; the spline motor 21 rotates to drive the spline rotating shaft 22 to rotate, cooperating with the rotation and axial movement of the mill bit 25 to couple and perform downhole milling of casing wear.

[0025] Working principle: When using this tool, the tool is suspended into the cased well through a cable, lowered to a predetermined position, and the sensor feeds back the position information. The power is transmitted through the cable in the cable tube to drive the hydraulic anchoring assembly to open the anchoring plate, tension the elastic plate, and anchor the tool to a predetermined position on the casing wall. The milling booster assembly drives the drilling pressure and torque to the milling oil at the predetermined position. The tool completes the axial feed through the ball screw, mills off the damaged part of the casing, and completes the work of well repair at the predetermined position.

[0026] The above specific embodiments are used to illustrate this patent rather than limit the scope of this patent. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principle of this patent fall within the protection scope of this patent system.

Claims

1. Downhole electric milling tool for casing damage, mainly composed of a housing, a hydraulic anchoring assembly, and a milling boost assembly; characterized in that: The upper end cover (2) is threadedly connected to the positioning sleeve (3), with a gap left in between to vertically hoist the downhole tool with the cable (1) in clearance fit; The hydraulic anchoring assembly consists of an upper housing (4), a motor (5), an oil storage chamber (7), a plunger pump (8), an oil circuit component (9), an anchoring cylinder (12), an anchoring plate (13), a support frame (14), a spring (15), an elastic plate (16), a cable pipe (11), and a limit block (17); The upper housing (4) is threadedly connected to the positioning sleeve (3), and the lower end external thread is connected to the upper end internal thread of the middle housing (10); In the inner cavity, the motor (5) is connected to the plunger pump (8) through a coupling (6); The lower part of the plunger pump (8) is threadedly connected to the upper part of the cable hole (9c) of the oil circuit component (9); The plunger pump (8) is circumferentially fixed to the oil storage chamber (7), and the oil suction hole (4a) is coaxially fixed with the oil storage chamber hole. The anchoring plate (13) and the support frame (14) are bolted to the lower part of the anchoring cylinder (12). During hydraulic operation, the spring (15) limits the position of the anchoring cylinder (12), and during pressure relief, it enables the anchoring cylinder (12) to return. The external thread of the limit block (17) is connected to the lower part of the middle housing (10) and the upper part of the lower housing (20) by internal threads; The milling and boosting assembly consists of a hollow shaft motor (18), a ball screw (19), a spline motor (21), a lower housing (20), a spline rotating shaft (22), a positioning block (24), and a milling head (25); The hollow shaft motor (18) is fixedly connected to the lower part of the limit block (17) by screws. The hollow shaft motor (18) rotates to drive the nut (23) of the ball screw (19) to move axially downward, transmitting axial pressure to the milling head (25); The spline motor (21) is screw-connected to the lower housing (20), and the spline motor (21) is connected to the spline rotating shaft (22) through splines. The ball screw (19) axially fixes the spline rotating shaft (22). The lower part of the spline rotating shaft (22) has an interference fit with the bearing of the ball screw (19). The internal thread of the milling head (25) is connected to the external thread of the spline rotating shaft (22). The spline motor (21) rotates to drive the spline rotating shaft (22) to rotate, causing the milling head (25) to couple rotational motion and axial motion to complete downhole casing milling work.

2. The downhole electric milling tool for casing damage according to claim 1, wherein: The upper housing (4) of the hydraulic anchoring assembly is provided with an oil suction hole (4a), a throttle valve groove (4b), and a cable pipe (4c); The oil circuit component (9) is provided with an oil drain hole (9a), an oil inlet hole (9b), and a cable hole (9c); The oil storage chamber (7) stores hydraulic oil from the oil suction hole (4a). After the plunger pump (8) sucks oil from the oil storage chamber (7), it pumps the high-pressure oil into the upper sealed inner cavity of the anchoring cylinder (12) and the middle housing (10) through the oil inlet hole (9b), pushing the axial anchoring mechanism of the anchoring cylinder (12) to tighten.

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