DOWNHOLE CUTTING TOOL

Abstract

A downhole cutting tool (13) for perforating a tubular (14) in an oil or gas well comprises a body (4); radially moveable cutting members (3) mounted on the body (4); a helical profiled member (1) rotatable relative to the body (4); and activation members (2) axially movable relative to the body (4). Rotation of the helical profiled member (1) generates axial movement of the activation members (2), and the activation members (2) configured to actuate the cutting members (3) from a retracted configuration to an extended configuration.

Claims

1. A downhole cutting tool for perforating a tubular in an oil or gas well, comprising: a body; a radially moveable cutting member mounted on the body; a helical profiled member rotatable relative to the body; and an activation member axially movable relative to the body; wherein rotation of the helical profiled member generates axial movement of the activation member, and wherein the activation member is configured to actuate the cutting member from a retracted configuration to an extended configuration.

2. A downhole cutting tool as claimed in claim 1, wherein the activation member is axially movable along the helical profiled member.

3.-5. (canceled)

6. A downhole cutting tool as claimed in claim 1, wherein the tool further comprises an annular sealing tool.

7. A downhole cutting tool as claimed in claim 6, wherein the tool comprises separable parts allowing a first part of the tool to be retrieved from a well and a second part to remain in the well, and wherein the second part includes the annular sealing tool.

8. (canceled)

9. A downhole cutting tool as claimed in claim 1, the tool comprising multiple radially moveable cutting members and wherein the cutting members are actuated at least one of singularly, in sequence, and simultaneously.

10. A downhole cutting tool as claimed in claim 1, wherein the tool comprises at least two activation members.

11. (canceled)

12. A downhole cutting tool as claimed in claim 1, the tool comprising an anchor mechanism and wherein the anchor mechanism comprises at least one anchor.

13. A downhole cutting tool as claimed in claim 1, wherein the activation member is axially translatable along an axial profile provided in the body.

14. A downhole cutting tool as claimed in claim 1, wherein the tool body comprises a through bore which allows fluids and members to pass through the bore of the tool.

15.-16. (canceled)

17. A method of perforating a downhole tubular in an oil or gas well, the method comprising: locating a downhole cutting tool in a downhole tubular; axially translating an activation member along a body of the downhole cutting tool by rotating a helically profiled member; and translating the activation member into engagement with a cutting member mounted on the body to actuate the cutting member from a retracted configuration to an extended configuration.

18. The method of claim 17, further comprising axially translating the activation member along the helical profiled member.

19. The method of claim 17, further comprising anchoring the cutting tool in the downhole tubular.

20. The method of claim 17, further comprising sealing the cutting tool in the downhole tubular.

21. The method of claim 17, further comprising retrieving a first part of the downhole cutting tool from the downhole tubular while a second part of the tool remains in the downhole tubular.

22. The method of claim 21, further comprising sealing the downhole tubular with the second part of the tool.

23. The method of claim 17, further comprising perforating the downhole tubular by radially translating the cutting member through the tubular.

24. The method of claim 17, further comprising actuating multiple cutting members in sequence.

25. The method of claim 17, further comprising translating multiple activation members.

26. The method of claim 17, further comprising passing fluid through the downhole cutting tool, and then occluding a through bore in the downhole cutting tool.

27. (canceled)

28. A downhole cutting tool for perforating a downhole tubular in an oil or gas well, comprising: a body; an anchor mechanism comprising at least one anchor for selectively anchoring the body relative to a surrounding downhole tubular; a radially moveable cutting member mounted on the body and having an inner cam surface; a helical profiled member rotatable relative to the body and for coupling to a drill string; and an activation member axially movable relative to the body and having an outer cam surface; wherein, with the anchoring mechanism activated to anchor the body to a surrounding downhole tubular, rotation of the helical profiled member relative to the body and driven by rotation of a drill string coupled to the helical profiled member, generates axial movement of the activation member, and wherein the outer cam surface of the activation member is configured to cooperate with the inner cam surface of the radially movable cutting member and actuate the radially movable cutting member from a retracted configuration to an extended cutting configuration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In the accompanying drawings,

[0066] FIG. 1 shows a schematic side view of the proposed embodiment of the tool.

[0067] FIG. 2 shows a perspective view of the proposed cutting tool in the dormant position, prior to making any cuts.

[0068] FIG. 3 shows a perspective side view of the proposed cutting tool during a conduit cut.

[0069] FIG. 4 shows a perspective side view of the proposed cutting tool following a conduit cut.

[0070] FIG. 5 shows a schematic side view of the proposed cutting tool assembly whilst running into the conduit.

[0071] FIG. 6 shows a schematic side view of the proposed cutting tool assembly with the anchor engaged, prior to making any conduit cuts.

[0072] FIG. 7 shows a schematic side view of the proposed cutting tool assembly during the initial conduit cut.

[0073] FIG. 8 shows a schematic side view of the proposed cutting tool assembly following the completion of the conduit cuts with the anchor still set.

[0074] FIG. 9 shows a schematic side view of the anchor set in the conduit with the proposed cutting tool disconnected via the disconnect sub.

[0075] FIG. 10 shows a schematic side view of the proposed cutting tool assembly following the completion of the conduit cuts, with the anchor released, being recovered to surface.

DETAILED DESCRIPTION OF THE DRAWINGS

[0076] FIG. 1 shows a schematic side view of one possible embodiment of the device which encompasses the cutting tool 13, anchor 12 and disconnect tool 6. The tool assembly can be made up to the drill string 20 (FIG. 2) using the upper drill string connection 9. The lower connection 11 allows the tool to be positioned at any location within the drill string 20 and allows for further components to be added below such as but not limited to scrapers, mills, etc. The tool assembly is illustrated located within a conduit 14 which will typically be a section of casing, but may be production tubing, liner, or the like. The design of the tool allows for a through bore 10 to be maintained such that fluid and objects such as balls, darts and plugs may pass through the tool.

[0077] FIG. 1 shows the cutting tool 13 which comprises of a series of radially movable cutting members 3 housed in windows or ports 22 in the tool body 4. The windows 22 permit radial movement of the respective cutting members 3 while restricting axial and circumferential movement. The cutting members 3 are circumferentially and axially spaced along the body 4. An outer surface 24 of each cutting member 3 tapers to a point 26 to facilitate penetration of the surrounding conduit 14. An inner cutting member surface 28 is cammed to cooperate with an activation member 2.

[0078] The helical profiled member 1 is located within the tool body 4. The member 1 is secured to prevent axial movement relative to the body 4 but is rotatable relative to the body 4 and is supported on appropriate bearings 30, 32. An outer surface of the member features a helical profile 5, for example an Acme thread, but any appropriate thread form may be utilised. The profile 5 cooperates with a corresponding profile 34 provided on an inner surface of each activation member 2. Each activation member 2 has a cammed outer surface 36 to cooperate with the inner cutting member surfaces 28, as will be described below. The activation members 2 are located in respective axially extending slots 38 on the tool body inner diameter 40; the slots 38 permit axial translation of the activation members 2 but prevent radial and circumferential translation of the members 2.

[0079] The upper drill string connection 9 is provided in the upper end of the helical profiled member 1 such that, as the drill string is rotated (with the tool body 4 fixed against rotation), the helical profiled member 1 rotates and the activation member 2 is translated along the axis of the tool. After a predetermined torque value and/or number of rotations of the string, the activation member 2 will activate the cutting member 3. In particular, the activation member 2 will be axially translated down through the tool body 4 and the activation member cam surface 36 will engage with an inner cutting member cam surface 28, further axial translation pushing the cutting member 3 radially outwards and into contact with the inner surface of the surrounding conduit 14. The radial movement of the cutting member 3 is continued to the extent necessary to breach the wall of conduit 14; the operator will be aware of the dimensions and material properties of the conduit 14 and whether the conduit 14 is surrounded by a cement sheath, and will thus have determined the radial extension of the cutting member 3 that will be required to perforate the conduit 14 and configured the tool accordingly.

[0080] Further rotation continues the movement of the activation member 2 beyond the cutting member 3, allowing the cutting member 3 to retract. Where multiple cutting members 3 are present a continuation of the above will activate cutting members 3 sequentially or in unison. Sequential operation allows all the torque being applied to the tool to be utilised to translate a single cutting member 3 at a time.

[0081] FIG. 1 depicts an embodiment of the tool with a disconnect tool 6, which allows the cutting tool 13 to be recovered to surface, leaving the anchor 12 downhole if desired. The disconnect tool 6 is provided between the lower end of the cutting tool 13 and the anchor 12 and includes releasable couplings, such as shear pins 42. Of course, the force necessary to shear the pins 42, which may be at least one of string torque and tension, will be higher than that necessary to operate the cutting tool 13.

[0082] The anchor 12 comprises a tubular body 44 which carries upper and lower anchor slips 7, and a sealing element 8 between the slips 7. The illustrated anchor 12 is fluid pressure activated and includes an external actuating piston 46 having an upper end face bearing against the lower slips 7. A pressure-communicating port 48 extends between the tool bore 10 and an annular chamber 50 provided between the anchor body 44 and the piston 46 such that an increase in pressure within the tool bore 10 is communicated to the chamber 50 and urges the piston 46 to travel upwards and against the slips 7, causing the slips 7 to extend radially outwards to grip the conduit 14, and the sealing element 8 to be axially compressed and radially extended into sealing contact with the conduit.

[0083] The anchor 12 may be initially retained in a dormant position, for example by provision of shear couplings between the piston 46 and the body 44, or a spring may be provided to bias the piston 46 towards a slip and seal retracting position.

[0084] The fluid pressure required to set the anchor 12 may be achieved by, for example, providing a flow restriction or occlusion below the anchor 12 and operating surface pumps to increase the pressure in the bore 10. The flow restriction may take any suitable form, for example a valve that remains open at low flow rates but closes when the flow rate through the valve increases, or may be a ball or dart that may be dropped into the string from surface to land on a seat below the anchor 12. The ball or dart may be subsequently displaced, for example by deforming the ball or by reconfiguring the dart to pass through the seat.

[0085] FIGS. 2, 3 and 4 show the cutting tool 13 with the activation member 2 at various positions, showing the activation cycle of the cutting member 3.

[0086] In FIG. 2, rotation of the drill string 20 and the helical profiled member 1 has moved the activation member 2 along the axis of the helical profiled member 1 and into contact with the uppermost cutting member 3.

[0087] FIG. 3 shows the activation member 2 having moved further along the axis of the helical profiled member 1 and fully energising the cutting member 3, driving the cutting member 3 outwards in contact with the conduit 14 being cut, resulting in a cut 15 to the conduit.

[0088] In FIG. 4, the cutting tool 13 has seen further rotation moving the activation member 2 further along the axis of the helical profiled member 1. The activation member 2 is positioned in a manner so that the cutting tool 13 is dormant, and the activation member 2 is not activating any of the cutting members 3. This allows the uppermost cutting member 3 to retract back into the tool body 4.

[0089] FIG. 5 shows the cutting tool assembly whilst running into the conduit 14. The activation member 2 is at the upper end of the helical screw feature 5 and the cutting members 3 have not been activated.

[0090] FIG. 6 shows the tool in position at the required cut depth with the anchor 12 activated and engaged. The anchor slips 7 and the sealing element 8 are engaged with the conduit bore 14, securing the tool in place and allowing for rotation of the drill pipe to be transmitted to the helical profiled member 1.

[0091] FIG. 7 shows the position of the components following the transmission of torque to the helical profiled member 1. The drill string rotation results in the activation member 2 moving along the axis of the helical screw feature 5 and driving the cutting member 3 outwards into contact with the conduit 14, resulting in a cut 15 being made. At this point the anchor 12 is still set in the conduit bore 14.

[0092] FIG. 8 shows the positioning of components once the required cuts 15 have been made in the conduit 14. The activation member 2 is at the end of the helical screw feature 5 and the cutting members 3 have retracted into the tool body 4 after sequentially making the cuts 15 as the activation member 2 moved along the helical profiled member 1 (as shown in FIGS. 2 to 4). The anchor 12 is still set with the anchor slips 7 and the sealing element 8 engaged with the conduit 14.

[0093] FIG. 9 illustrates the option to disconnect from the anchor 12, leaving the anchor 12 set downhole. In this figure the cutting tool 13 can be seen to have been released from the anchor 12 by the disconnect tool 6, for example by application of an over-torque, overpull, or combination of both. The tool through bore 10 is maintained and therefore provides a means of placing cement or other fluids on top of the anchor 12. The cutting members 3 have retracted into the body and the cutting tool 13 can be pulled out of hole.

[0094] FIG. 10 shows the option of recovering the system by releasing the anchor 12 and recovering the anchor 12 and cutting tool 13 from the wellbore. As the cutting members 3 are retracted this can be completed without risk of engaging with the existing cuts 15 in the conduit 14.

[0095] From the above description it will be apparent that the illustrated tool assembly allows downhole tubing to be perforated by a relatively simple operation, and without the use of perforation charges. As described above, the torque to operate the tool may be provided via a drill pipe string, which may be rotated at surface using a top drive or rotary table. In other examples the torque may be provided by other arrangements, for example downhole motors.

[0096] The above example features a helical profile 5 having a thread-like form, however in other examples the activation members 2 may travel along a plain helical slot or groove. The form of the helical profile may be constant, such that the relationship between rotation of the helical profiled member 1 and axial translation of the activation member 2 remains constant as the activation members 2 travel down the member 1. However, in other examples the helix angle or other feature of the profile may vary such that, for example, with a constant rate of rotation of the drill string 20 and the member 1, the rate of axial translation of an activation member 2 decreases as the member 2 engages a cutting member 3.

[0097] The tool is described above for use in perforating tubing, but in certain operations an operator may wish only to deform a tubular and in such an example the cutting members may have a different external profile.

[0098] When a cutting member is extended into contact with the surrounding tubular there will be a tendency for the tool to move towards the opposite side of the bore. The radial extension of the cutting members may be selected to accommodate this movement, or in other examples stabilising or supporting members may be provided to limit the movement of the tool. The stabilising or supporting members may be static, for example solid stabiliser blades, or support members may extend from the opposite side of the body in unison with the cutting members. Such support members may be activated in a similar manner to the cutting members, that is via activation members that are axially translated down the tool body.

[0099] The cutting members 3 may be in sealing engagement with the respective body windows 22 or may simply be a close or loose fit with the windows 22. If in sealing engagement the extension of the members 3 may be assisted by internal tool pressure if, for example, a flow restriction is provided in the bore 10 below the tool. The cutting members 3 may be biased towards the retracted configuration by appropriate springs or may simply be free to retract once the activation member 2 has moved past the member 3.

[0100] The tool bore 10 may be selectively occluded by, for example, dropping a ball or dart into the tool. The ball or dart may be subsequently displaced to reinstate flow through the tool.

REFERENCE NUMERALS

[0101] helical profiled member 1 [0102] activation member 2 [0103] cutting members 3 [0104] tool body 4 [0105] helical profile 5 [0106] disconnect tool 6 [0107] anchor slips 7 [0108] sealing element 8 [0109] upper drill string connection 9 [0110] through bore 10 [0111] lower drill string connection 11 [0112] anchor 12 [0113] cutting tool 13 [0114] conduit 14 [0115] cut 15 [0116] drill string 20 [0117] windows 22 [0118] cutting member outer surface 24 [0119] cutting member point 26 [0120] cutting member inner surface 28 [0121] bearings 30, 32 [0122] activation member profile 34 [0123] cam surface 36 [0124] axially extending slots 38 [0125] tool body inner diameter 40 [0126] shear pins 42 [0127] anchor body 44 [0128] actuating piston 46 [0129] pressure-communicating port 48 [0130] chamber 50