Underground hydraulic cutting knife

Abstract

The underground hydraulic cutting knife comprises an outer sleeve, a pressure pushing mechanism and a cutting knife mechanism, wherein a plurality of knife grooves are uniformly formed in the outer sleeve in the circumferential direction; the pressure pushing mechanism is arranged in the outer sleeve; the cutting knife mechanism is arranged in the outer sleeve and is positioned below the pressure pushing mechanism; the cutter mechanism comprises a blade bushing which can move up and down and is arranged in the outer sleeve, and a plurality of blade assemblies which are circumferentially and rotatably arranged on the blade bushing; the pressure pushing mechanism can move up and down so as to extrude the blade assemblies, so that the blade assemblies are expanded and extend out of the blade grooves respectively; the blade assembly comprises a first blade and a second blade which are attached to each other, and the length of the first blade is larger than that of the second blade. According to the utility model, the second blade and the first blade are respectively adopted to cut the inner and outer layers of sleeves, so that the resistance to a single blade is reduced, and the risk of blade breakage is reduced.

Description

A type of downhole hydraulic cutter Technical Field

[0001] This utility model relates to the field of oil and gas field tools technology, specifically to a downhole hydraulic cutter. Background Technology

[0002] During drilling, multiple layers of casing are run to stabilize the wellbore and separate the wellbore from the producing formation. After running, the casing may corrode, deform, or experience pressure buildup due to geological movements or long-term production, all of which affect wellbore integrity. Such problems require prompt and timely intervention to prevent significant well control issues. However, once the casing has been run and cemented, retrieving the problematic casing or addressing the pressure buildup in the cement sheath becomes extremely challenging. Therefore, cutting the casing becomes a crucial step in effectively addressing wellbore integrity issues related to the casing and annulus.

[0003] Hydraulic cutters are a type of mechanical cutter used to cut through the inside of casing, tubing, and drill pipe. They are primarily used for operations requiring precise control of shape and cutting position. However, existing hydraulic cutters are prone to breakage when used for cutting double-layer casing, affecting the progress of construction work. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a downhole hydraulic cutting tool.

[0005] The purpose of this utility model is achieved through the following technical solution: a downhole hydraulic cutter, comprising an outer sleeve with a plurality of blade grooves evenly arranged in the circumferential direction, a pressure pushing mechanism disposed inside the outer sleeve, and a cutting mechanism disposed inside the outer sleeve and located below the pressure pushing mechanism;

[0006] The cutting mechanism includes a blade bushing that can move up and down inside the outer sleeve, and a plurality of blade assemblies that can be rotatably arranged on the blade bushing; the pressure pushing mechanism can move up and down to squeeze the blade assemblies, causing the blade assemblies to expand and extend out of the blade groove respectively;

[0007] The blade assembly includes a first blade and a second blade that are fitted together, wherein the length of the first blade is longer than the length of the second blade.

[0008] Furthermore, a second spring is fitted on the blade bushing for pushing the cutting mechanism upward to reset.

[0009] The pressure-driven mechanism includes a support plate fixedly installed inside the outer casing, a piston disposed inside the outer casing and located below the support plate, a connecting sleeve disposed on the top of the piston, a packing ring disposed on the piston, a guide rod with its lower end penetrating through the support plate and its upper end disposed on a nozzle, and a first spring sleeved on the guide rod and located between the nozzle and the support plate; the lower end of the guide rod is connected to the connecting sleeve.

[0010] The upper part of the outer jacket is detachably connected to an upper connector.

[0011] The lower end of the outer jacket is connected to a guide cone, and the guide cone has a liquid outlet hole that communicates with the inner hole of the outer jacket in a radial direction.

[0012] Compared with the prior art, this application has the following beneficial effects: the present invention uses a second blade and a first blade to cut the inner and outer sleeves respectively, reducing the resistance of a single blade and reducing the risk of blade breakage.

[0013] Some of the additional features of this application will be described in the following description. These additional features will become apparent to those skilled in the art upon examination of the following description and the accompanying drawings, or upon understanding the production or operation of the embodiments. The features disclosed in this application can be implemented and achieved through the practice or use of various methods, means, and combinations thereof with respect to the specific embodiments described below. Attached Figure Description

[0014] The accompanying drawings, which are provided to further illustrate this application and constitute a part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute a limitation thereof. In the drawings, the same reference numerals denote the same components.

[0015] Figure 1 is a schematic diagram of the structure of this utility model.

[0016] Figure 2 is a cross-sectional view of this utility model.

[0017] Figure 3 is a schematic diagram of the blade assembly of this utility model.

[0018] The reference numerals in the above figures are as follows: 1-upper connector, 2-nozzle, 3-guide rod, 4-first spring, 5-support plate, 6-outer sleeve, 7-piston, 8-blade assembly, 81-first blade, 82-second blade, 9-blade bushing, 10-second spring, 11-liquid outlet, 12-guide cone, 13-packing, 14-connecting sleeve, 15-blade groove. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments.

[0020] Example

[0021] As shown in Figure 1, this embodiment discloses a downhole hydraulic cutter, which includes an outer sleeve 6, a pressure pushing mechanism, and a cutting mechanism. The outer sleeve 6 has an axial through hole inside, with the diameter of the upper section of the through hole being larger than the diameter of the lower section. The upper end of the outer sleeve 6 is detachably connected to an upper connector 1 via a thread, and its lower end is also detachably connected to a guide cone 12 via a thread. Similarly, the upper connector 1 also has an axial through hole inside, which communicates with the through hole inside the outer sleeve 6. The guide cone 12 has a radially opening liquid outlet hole 11 that communicates with the internal through hole of the outer sleeve 6. Setting the opening direction of the liquid outlet hole 11 perpendicular to the axis of the guide cone 12 reduces the risk of the liquid outlet hole 11 becoming blocked.

[0022] Both the pressure pushing mechanism and the cutting mechanism are located inside the outer sleeve 6, with the cutting mechanism positioned below the pressure pushing mechanism. The outer wall of the outer sleeve 6 has several uniformly spaced cutting grooves 15. Specifically, the cutting mechanism includes a blade bushing 9 that can move vertically inside the outer sleeve 6, and several blade assemblies 8 that are rotatably mounted on the blade bushing 9. During setup, the blade assemblies 8 are mounted on the blade bushing 9 via pins, allowing them to rotate around these pins, thus expanding or contracting. The number and position of the blade assemblies 8 correspond one-to-one with the number and position of the cutting grooves 15; that is, one cutting groove 15 corresponds to one blade assembly 8. When the blade assembly 8 expands, its cutting end extends from the cutting groove 15, thereby cutting the sleeve.

[0023] As shown in Figure 3, the blade assembly 8 includes a first blade 81 and a second blade 82 that are fitted together. The length of the first blade 81 is longer than the length of the second blade 82. When the tool performs a rotary cutting motion, the second blade 82 is located in front of the first blade 81. The second blade 82 first cuts the inner sleeve, and then the first blade 81 cuts the outer sleeve. By distributing the cutting resistance of the inner and outer sleeves to the second and first blades, the resistance experienced by a single blade is reduced, thus lowering the risk of blade breakage.

[0024] In addition, a second spring 10 is fitted on the blade bushing 9 for pushing the cutting mechanism upward to reset. Specifically, the second spring 10 is located at the bottom of the large-diameter section of the inner through hole of the outer sleeve 6. The diameter of the second spring 10 is larger than the diameter of the small-diameter section of the through hole of the outer sleeve 6. The cutting mechanism is located above the first spring 10, so when the cutting mechanism moves downward, the second spring 10 is compressed.

[0025] The pressure-driven mechanism can move up and down and is used to push the cutting mechanism. When the pressure-driven mechanism moves downward, its lower end presses against the upper end of all blade assemblies 8, causing all blade assemblies 8 to expand around the pin. At the same time, due to the pressure from the pressure-driven mechanism, the entire cutting mechanism also moves downward, and the second spring 10 is compressed. When the pressure from the pressure-driven mechanism disappears, the cutting assembly 8 contracts under its own weight, and the second spring 10 pushes the cutting mechanism upward to reset. The cutting assembly 8 then abuts against the upper end of the blade groove 15, further promoting the contraction of the cutting assembly 8.

[0026] As shown in Figure 2, the pressure pushing mechanism includes a support plate 5 fixedly installed inside the outer casing 6, a piston 7 disposed inside the outer casing 6 and located below the support plate 5, a connecting sleeve 14 disposed on the top of the piston 7, a packing 13 disposed on the piston 7, a guide rod 3 with its lower end penetrating through the support plate 5 and its upper end disposed on a nozzle 2, and a first spring 4 sleeved on the guide rod 3 and located between the nozzle 2 and the support plate 5; the lower end of the guide rod 3 is connected to the connecting sleeve 14.

[0027] Specifically, the support plate 5 can be fixed inside the outer casing 6 by pins. Multiple liquid inlets are evenly arranged around its circumference. The guide rod 3 passes through the center of the support plate 5, with a clearance fit between them. Therefore, the guide rod 3 can move up and down relative to the support plate 5. The positioning function of the support plate 5 makes the guide rod 3 more stable when moving up and down. When the guide rod 3 and the nozzle 2 move down together, the first spring 4 is compressed.

[0028] The diameter of the packing 13 matches the inner diameter of the outer sleeve 6, serving as a sealing plug. When the packing 13 is subjected to downward pressure, it pushes the piston 7 downward, causing the lower end of the piston 7 to press against the upper end of the cutter assembly 8, thereby expanding the cutter assembly 8. The connecting sleeve 14 is located at the center of the packing 13. The nozzle 2, guide rod 3, connecting sleeve 14, packing 13, and piston 7 all have inner holes, and the inner holes of the nozzle 2, guide rod 3, connecting sleeve 14, packing 13, and piston 7 are connected to form a passage. The inner hole of the guide rod 3 is smaller than the inner holes of the connecting sleeve 14, packing 13, and piston 7.

[0029] In use, the hydraulic cutter is lowered to the designated position using a tool string. Drilling fluid is introduced through the tool string's upper connector 1. Part of the drilling fluid flows downwards along the nozzle 2, guide rod 3, connecting sleeve 14, packing 13, and piston 7, while the other part passes through the fluid inlet on the support plate 5 and impacts the packing 13. Once the nozzle 2, guide rod 3, connecting sleeve 14, packing 13, and piston 7 are filled with drilling fluid, all the drilling fluid flows downwards from the inner holes of the nozzle 2, guide rod 3, and connecting sleeve 14, creating a pressure drop. This causes the guide rod 3, packing, and piston 7 to descend. The lower end of piston 7 pushes the cutting assembly 8 to expand, which in turn drives the hydraulic cutter to rotate via the tool string. The cutting assembly 8 then cuts the inner and outer casings. The downward-flowing drilling fluid can be discharged from the cutter groove or through the inner holes of the blade bushing 9 and outer casing 6, and then discharged from the outlet hole 11 on the guide cone 12. After the drilling fluid supply is stopped, the guide rod and the cutting mechanism return to their original position upwards under the action of the first and second springs, and the cutting assembly retracts.

[0030] It should be noted that all features disclosed in this specification, or all steps in all methods or processes disclosed, may be combined in any way, except for mutually exclusive features and / or steps.

[0031] Furthermore, the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this utility model, and these solutions all fall within the scope of this utility model and its protection. Those skilled in the art should understand that this utility model specification and its drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this utility model is defined by the claims and their equivalents.

Claims

1. A downhole hydraulic cutter, characterized in that, The device includes an outer sleeve (6) with a plurality of uniformly arranged circumferential grooves (15), a pressure pushing mechanism disposed inside the outer sleeve (6), and a cutting mechanism disposed inside the outer sleeve (6) and below the pressure pushing mechanism; the cutting mechanism includes a blade bushing (9) disposed inside the outer sleeve (6) that can move up and down, and a plurality of blade assemblies (8) disposed on the blade bushing (9) that can rotate circumferentially; the pressure pushing mechanism can move up and down to squeeze the blade assemblies (8), so that the blade assemblies (8) expand and extend from the grooves (15); the blade assembly (8) includes a first blade (81) and a second blade (82) that fit together, wherein the length of the first blade (81) is longer than the length of the second blade (82).

2. The downhole hydraulic cutter according to claim 1, characterized in that, The blade bushing (9) is fitted with a second spring (10) for pushing the cutting mechanism upward to reset.

3. The downhole hydraulic cutter according to claim 1, characterized in that, The pressure-driven mechanism includes a support plate (5) fixedly installed inside the outer casing (6), a piston (7) disposed inside the outer casing (6) and located below the support plate (5), a connecting sleeve (14) disposed on the top of the piston (7), a packing (13) disposed on the piston (7), a guide rod (3) with its lower end penetrating through the support plate (5) and its upper end provided with a nozzle (2), and a first spring (4) sleeved on the guide rod (3) and located between the nozzle (2) and the support plate (5); the lower end of the guide rod (3) is connected to the connecting sleeve (14).

4. The downhole hydraulic cutter according to claim 1, characterized in that, The upper end of the outer jacket (6) is detachably connected to an upper connector (1).

5. The downhole hydraulic cutter according to claim 1, characterized in that, The lower end of the outer jacket (6) is connected to a guide cone (12), and the guide cone (12) has a liquid outlet hole (11) that communicates with the inner hole of the outer jacket (6) in a radial direction.

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