Improvements In Or Relating To Wellbore Operations

Abstract

A method and apparatus to move an object in an open hole section of a wellbore. A bottom hole assembly including a downhole pulling tool and fishing device is described. The downhole pulling tool includes an open hole anchor to allow location of the downhole pulling tool in the open hole section of the wellbore so as to reduce the operating distance between the downhole pulling tool and the fishing device. An embodiment in which a cut section of tubular is removed from the open hole section is described. A casing cutter may also be located in the bottom hole assembly to cut the tubular on the same trip in the well as removing the cut section of tubular.

Claims

1. A method to move an object in an open hole section of a wellbore, comprising the steps: (a) providing a downhole assembly on a work string, the downhole assembly including a downhole pulling tool and a fishing device; (b) running the work string in the well bore and the downhole assembly into the open hole section; (c) gripping the object with the fishing device; (d) anchoring the downhole assembly to a wall of the open hole section by contacting an elastomeric anchor element of the assembly to the wall of the open hole section; (e) operating the downhole pulling tool to pull the object; (f) releasing the downhole assembly from the wall of the open hole section; and (g) raising the work string to remove the downhole assembly from the wellbore.

2. The method according to claim 1 wherein at step (g) the object is removed from the wellbore on the work string.

3. The method according to claim 1 wherein the elastomeric anchor element comprises a packer element and step (d) comprises inflating the packer element to contact the wall and step (f) comprises deflating the packer element to disengage from the wall of the open hole section.

4. The method according to claim 1 wherein step (d) further comprises engaging the wall with at least one gripping element of the downhole assembly and step (f) comprises releasing the gripping element from the wall of the open hole section.

5. The method according to claim 3 wherein the packer element is on an open hole packer which is retrievable.

6. The method according to claim 4 wherein the open hole packer is resettable.

7. (canceled)

8. (canceled)

9. The method according to claim 8 wherein the method includes the additional steps, between steps (f) and (g), of raising the work string to move the downhole pulling tool until movement is prevented as the cut section of tubular remains stuck; re-anchoring the downhole assembly to the wall of the open hole section; operating the downhole pulling tool to pull the cut section of tubular; and releasing the downhole assembly from the wall of the open hole section.

10. The method according to claim 8 wherein the method includes the additional steps, between steps (f) and (g), of raising the work string to move the downhole pulling tool until movement is prevented as the cut section of tubular is stuck; re-anchoring the downhole assembly to a wall of outer casing located uphole of the open hole section; operating the downhole pulling tool to pull the cut section of tubular; and releasing the downhole assembly from the wall of outer casing.

11. The method according to claim 1 wherein the method includes an additional step of jetting fluid from the downhole assembly to wash the wall of the open hole section against which the downhole assembly will be anchored.

12. The method according to claim 1 wherein the object is a cut section of tubular and the method includes the additional steps of including a cutting tool in the downhole assembly at step (a) and using the cutting tool to cut the tubular to form the cut section of tubular.

13. Apparatus to move an object in an open hole section of a wellbore, comprising a string for running into the well, the string being arranged to carry a fluid in a throughbore thereof and including a downhole assembly, the downhole assembly comprising: a downhole pulling tool, the downhole pulling tool comprising an open hole anchor including an elastomeric anchor element for axially fixing the downhole assembly to a borehole wall of an open section of the wellbore and an inner mandrel axially moveable relative to the anchor in response to the fluid in the throughbore; a fishing device connected to the inner mandrel for engaging the object; wherein an increase in fluid pressure in the throughbore operates the downhole pulling tool to anchor the downhole assembly to the borehole wall, raise the inner mandrel relative to the open hole anchor and pull the object.

14. Apparatus according to claim 13 wherein the open hole anchor is re-settable.

15. Apparatus according to claim 14 wherein the elastomeric anchor element comprises an inflatable packer element.

16. Apparatus according to claim 14 wherein the anchor further comprises at least one gripping element to engage the borehole wall in the open hole section.

17. Apparatus according to claim 13 wherein the downhole pulling tool includes a housing supported in the well by the string and enclosing a plurality of axially stacked pistons generating a cumulative axial force, each of the plurality of pistons axially movable in response to the fluid increase in the throughbore; and wherein movement of the pistons also moves the inner mandrel.

18. Apparatus according to claim 13 wherein the fixing device is selected from a group comprising: a spear, an overshot, a grapple and an anchor.

19. Apparatus according to claim 18 wherein the spear comprises: a sliding assembly mounted on the inner mandrel; at least one gripper for gripping onto an inner wall of the object, the gripper being coupled to the sliding assembly; the sliding assembly being operable for moving the gripper between a first position in which the gripper is arranged to grip onto the inner wall of the object in at least one gripping region of the object and a second position in which the gripper is held away from the inner wall; and a switcher which, when advanced into the object, locks the sliding assembly to the inner mandrel with the gripper in the second position; and, when the casing spear is pulled upward out of the stuck object and the switcher exits the end of the object, automatically allows engagement of the object by the gripper in the first position.

20. Apparatus according to claim 13 wherein the downhole assembly includes a valve for blocking the flow of fluid through the throughbore, the valve being located between the downhole pulling tool and the fishing device, wherein the valve is closed by raising the downhole pulling tool relative to the fishing device when the fishing device engages the object and opened by setting pressure down on the downhole pulling tool.

21. Apparatus according to claim 13 wherein the object is a cut section of tubular and the downhole assembly further comprises a cutting tool to cut the tubular and form the cut section of tubular.

22. Apparatus according to claim 13 wherein the downhole assembly further comprises a jetting tool to wash an inner wall of the open hole section.

Description

[0046] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which:

[0047] FIG. 1 is a schematic illustration of a downhole apparatus for moving an object in an open hole section of a wellbore according to an embodiment of the present invention;

[0048] FIG. 2 is a schematic illustration of a wellbore with an open hole section in which tubular is to be retrieved using apparatus according to an embodiment of the present invention;

[0049] FIG. 3 is the arrangement of FIG. 2 now showing the spear engaged and the tubular being cut according to an embodiment of the present invention;

[0050] FIG. 4 is the arrangement of FIG. 2 now showing the spear engaged and the downhole assembly anchored to the borehole wall of the open hole section according to an embodiment of the present invention;

[0051] FIG. 5 is the arrangement of FIG. 2 now showing the downhole pulling tool operating to pull the cut section of tubular according to an embodiment of the present invention; and

[0052] FIG. 6 is the arrangement of FIG. 2 now showing the cut section of tubular being recovered from the open hole section of the wellbore.

[0053] Reference is initially made to FIG. 1 of the drawings which illustrates apparatus, generally indicated by reference numeral 10, for removing an object 12 from an open hole section 14 of a wellbore 16 according to an embodiment of the present invention. The apparatus 10 is located in the wellbore 16.

[0054] Wellbore 16 may be a vertical, horizontal or deviated well. In the example shown in FIG. 1, the wellbore 16 was completed using a casing string 18 which is typically run from surface (not shown) to a downhole location at the heel 20 of the wellbore 16. The casing 18 is cemented 19 in place, as is known in the art of well construction. The wellbore may then have been completed by drilling a borehole 22 and hanging a liner 24, or other tubular, from the casing shoe 26 at the heel 20. The liner 24 was held in place by packers 28 arranged along the length of the liner 24. Completion tools such as frac valves or sand screens may have been located between the packers 28. In FIG. 1, a section of the liner 24 has already been removed from the well from the heel 20 to the location of the packer 24a. This removal will have been completed by known casing recovery techniques. These casing recovery techniques would rely on anchoring removal apparatus to the inner wall 30 of the casing string 18. Operating any tools from a distant anchor point can cause elongation or reduced torqueing on the drill string therebetween which limits the operation of such tools. Thus, recovery of the liner 24 becomes difficult at distances further from the casing 18. This is further hampered by the packers or other equipment, together with sand and debris, which can be holding the liner 24 in place. While a lower completion of liner and packers 28 is illustrated, it will be appreciated that any arrangement in which a borehole is drilled to form an open hole section 14, where the borehole 22 wall 34 is exposed i.e. there is no cemented casing string, could be used. The object 12 is shown as the end of a liner 24, however, the object may be any object 12 located in the open hole section 14 such as other downhole components such as a valve, or an actuator of a downhole component for which movement thereof will cause an operation to be performed by the component e.g. moving a sliding sleeve to open a valve.

[0055] Apparatus 10 comprises a work string 32 which may be a drill string comprised of drill pipe sections run from surface, through which fluid can flow in a throughbore 36 thereof. A bottom hole assembly 38 is located at the end 40 of the work string 32. The bottom hole assembly 38 comprises in order from the end 40, a fishing device 47 (an overshot 49), a jetting tool 45, a valve 50 and a downhole pulling tool 52 made up of an open hole anchor 56 and an actuator system 58. Valve 50 is shown in the mandrel 54 of the pulling tool 52 but could be in the throughbore 36 anywhere below the pulling tool 52. Adjacent parts of the assembly 38 may be formed integrally on a single tool body or may be constructed separately and joined together by box and pin sections as is known in the art. Two or more parts may also be integrally formed and joined to any other part. Further parts may be included and drill pipe sections can be inserted between parts to provide a desired spaced apart relationship between the component parts. The work string 32 is typically run from a rig (not shown) via a top drive/elevator system which can raise and lower the string 32 in the wellbore 16.

[0056] The downhole pulling tool 52 can be considered as a hydraulic jack and has an open hole anchor 56 and an actuator system 58 which pulls the inner mandrel 54 up into a housing 60 of the tool 52. In a preferred embodiment the downhole pulling tool 52 is a modification of the DHPT available from Ardyne AS. It is described in U.S. Pat. No. 8,365,826, the disclosure of which is incorporated herein in its entirety by reference.

[0057] The open hole anchor 56 may be any arrangement of known open hole anchor but is preferably operated by fluid pressure in the throughbore 36. The open hole anchor 56 includes an elastomeric anchor element 62. In a preferred embodiment the elastomeric anchor element 62 is an inflatable packer which uses fluid from the throughbore 36 to fill a rubber bladder so as to expand and adhere to the borehole wall 34. By reducing the fluid pressure in the throughbore 36 the packer 62 may be deflated so as to be retrievable and re-settable in the wellbore 16. The packer 62 is used to hold the assembly 38 to the borehole wall 34 and thus does not need to create a seal. As the packers 62 use is also temporary, a rubber bladder will be suitable as the packer is not left downhole for isolation purposes.

[0058] Gripping elements 64 may also be present to assist in anchoring the assembly 38 to the borehole wall 34 of the open hole section 14 to allow the open hole packer 62 to set. While traditional slips could be used, it is likely that the gripping elements 64 will require to have a greater degree of travel to be able to span the annulus 66 and contact the borehole wall 34. As the open hole anchor 56 is to be retrievable, the gripping elements 64 need to be retractable and also preferably fluid operated. If used with a packer 62, the gripping elements 64 need not fully anchor to the borehole wall 34, but just provide sufficient hold for the packer 62 to be set.

[0059] The downhole pulling tool 52 also has an actuator system 58. This is as described in U.S. Pat. No. 8,365,826, the disclosure of which is incorporated herein by reference. The actuator system 52 has an outer housing 60 connected to the work string 32 and an inner mandrel 54 extending from the tool 52. Inside the housing 60, the mandrel 54 and housing 52 have an array of stacked pistons arranged therebetween. Fluid from the throughbore 36 enters a chamber between each pair of pistons and causes movement of the inner mandrel 54 relative to the static housing 60 (anchored to the borehole wall 34 by virtue of the anchor 56) to move the inner mandrel 54 into the housing 60 and so raise or pull any object connected to the mandrel 54. In FIG. 1, the remaining elements of the bottom hole assembly 38 are connected to the inner mandrel 54. The movement of a piston across a chamber to meet a neighbouring piston constitutes a stroke of the pulling tool 52. As there are multiple stacked pistons, the combined cross-sectional areas of the end faces when fluid pressure is applied generates a considerable lifting force via the inner mandrel 54.

[0060] The pulling tool 52 is configured to operate the open hole anchor 56 ahead of the actuator system 58. This creates the pulling action. The downhole pulling tool 52 is configured such that the grip force of the anchor is greater than the pull force on the object. The grip force of the packer used to anchor the assembly and the pull force of the downhole assembly are both proportional to the fluid pressure applied. By configuring the pulling tool such that the packer grip force is always higher than the mandrel pull force, the downhole pulling tool cannot stroke before the packer gets enough grip to prevent the packer sliding down the hole as you stroke the assembly, instead of the object moving up hole.

[0061] When fluid pressure is reduced, the anchor will unset, by virtue of the packer 62 being retrievable, and the fluid will exit the chambers so as to allow the pistons to return to their initial positions, at the opposite end of the stroke as the work string 32 is raised. The raising of the work string 32 repositions the pulling tool 52 at a location higher up in the wellbore 16. Fluid pressure in the throughbore 36 can be increased again and the process repeated to sequentially anchor the tool 52 and pull an object attached to the inner mandrel 54, any number of times, to move the object 12. Once the object is free, pulling the work string 32 should be able to pull the bottom hole assembly 38 and the object 12, in this case a cut section of liner 24, to surface for recovery.

[0062] To provide the increase in fluid pressure in the throughbore 36, a valve 50 is located below the pulling tool 52, in the mandrel 54. In FIG. 1, the valve 50 is illustrated as sitting directly below the housing 60, however the valve 68 may be positioned in any part of the mandrel below the pulling tool 52, its position being determined by other tools on the string 32. A suitable valve 50 is described in U.S. Pat. No. 8,365,826 being a ball valve operated via a drop ball. In a preferred embodiment, an ALO valve as supplied by Ardyne AS is used. The ALO valve is designed to form part of mandrel 54, and in which a valve is provided with a passage for fluid, the passage including an opening and closing mechanism. In use: a first valve portion is connected to the mandrel 54; second valve portion telescopic relative to the first valve portion is connected to a fishing device 47; in an initial position, the first valve portion and the second valve portion are held together under the force of a spring and arranged so that the opening and closing mechanism is open; pulling the mandrel 54 moves the first valve portion relative to the second valve portion thereby extending the valve to close the opening and closing mechanism. Thus the valve 50 advantageously can be cycled between open and closed positions by applying tension to the mandrel 54 on which the upper portion of the valve is attached. The ALO valve is described in WO2015065196, the disclosure of which is incorporated herein in its entirety by reference.

[0063] In the embodiment shown in FIG. 1, the fishing device 47 is an overshot 49. These are known and comprise a barrel arrangement which fits over the object, typically a tubular. A friction device in the overshot, usually either a basket or a spiral grapple, firmly grips the outer surface of the tubular, allowing the tubular to be pulled. The fishing device 47 may be any known device such as a grapple, anchor or spear.

[0064] Also shown in FIG. 1 is a jetting tool 45. Jetting tool 45 has a tubular body and a plurality of ports 51 through which washing fluid passed down the throughbore 36 is ejected. The ports 51 are arranged around the tool body to provide 360 degree coverage. Nozzles may be located in the ports 51 to increase the speed of the fluid, so that it crosses the annulus 66 and impacts the inner wall 34 of the open hole section 14. This allows the wall 34 to be cleared of sand and other debris which may prevent the packer 62 making a strong contact to the wall 34.

[0065] Reference is now made to FIGS. 2 to 5 which show the steps of removing an object, being a cut section of tubular, from the wellbore 16 according to an embodiment of the present invention. Like parts to those of FIG. 1 have been given the same reference numerals to aid clarity. The bottom hole assembly 38 comprises in order from the end 40, a taper mill 42, a casing cutter 44, a motor 46, a jetting tool 45, a fishing device being a spear 48, a valve 50 and a downhole pulling tool 52 made up of an open hole anchor 56 and an actuator system 58. Valve 50 is shown in the mandrel 54 of the pulling tool 52 but could be in the throughbore 36 anywhere below the pulling tool 52. The taper mill 42, casing cutter 44 and motor 46 are optional. Adjacent parts of the assembly 38 may be formed integrally on a single tool body or may be constructed separately and joined together by box and pin sections as is known in the art. Two or more parts may also be integrally formed and joined to any other part. Further parts may be included and drill pipe sections can be inserted between parts to provide a desired spaced apart relationship between the component parts. Incorporation of the casing cutter 44 and motor 46 allows the liner 24 to be cut to provide the cut section of tubular 12 on the same trip in the well as its recovery. The work string 32 is typically run from a rig (not shown) via a top drive/elevator system which can raise and lower the string 32 in the wellbore 16.

[0066] The downhole pulling tool 52 and valve 50 are as described hereinbefore. The jetting tool 45 is now located below the fishing device, spear 48, and has a narrower body so that it can locate in the liner 24.

[0067] Casing spear 48 operates as an anchor to grip the inner surface 70 of the length of liner 24. The casing spear anchors as a slip designed to ride up a wedge and by virtue of wickers or teeth on its outer surface grip and anchor to the inner surface 70 of the liner 24. The spear 48 includes a switch which allows the spear to be inserted into the liner 24 and hold the slips in a disengaged position until such time as the grip is required. At this time, the spear 48 is withdrawn from the end 72 of the liner 24 and, as the switch exits the liner 24, it automatically operates the slips which are still within the liner 24 at the upper end thereof. This provides the ideal setting position of the spear 48. In a preferred embodiment the casing spear 20 is the Flow Release Mechanism (FRM) Spear as provided by the Ardyne AS. The FRM Spear is described in WO2017059345, the disclosure of which is incorporated herein in its entirety by reference. The casing spear 48 is attached to the mandrel 54 below the valve 68 via a standard complimentary male and female screw threads as are known the art as a box and pin section.

[0068] Casing cutter 44 is a standard fluid pressure operated casing cutter. These casing cutters have a number of blades, typically three, which are held inside the body of the cutting mechanism as it is run in the wellbore 16. When cutting is required, fluid is pumped down the throughbore 36 of the string 32 from surface through the bottom hole assembly 38 and when sufficient fluid pressure is reached in the cutting mechanism, pistons are displaced which extend the pivoted blades outwards from the body to contact the inner wall 70 of the liner 24. By rotating the cutter mechanism by use of the downhole motor 46 located above the casing cutter 44, the blades will cut the liner 24 and produce a section of cut tubular 12. Downhole motor 46 is a positive displacement motor configured to convert hydraulic force of a pumped fluid through the work string 32 into a mechanical force to rotate the cutting mechanism.

[0069] At the end 40 of the work string 32 and bottom hole assembly 38 is a taper mill 42. The taper mill 42 has a pilot and an abrasive surface. It is rotated in use. Taper mill 42 will clear material in the open hole section 14 and bore through any material within the liner 24 as the bottom hole assembly 38 is run-in.

[0070] FIG. 2 shows the bottom hole assembly 38 has been lowered into the liner 24 on the work string 32. The bottom hole assembly 38 is lowered into the open hole section 14 after passing through the cased section 18. As the assembly 38 is run in, fluid will be circulated through the bore 36 and the assembly 38 and circulated up the annulus 66 to surface. The taper mill 42 clears a route through any material in the path and enters the end 72 of the liner 24. In this configuration, fluid pressure through the bottom hole assembly 38 is kept sufficiently low so that the pulling tool 52 and casing cutter 44 are not actuated. The jetting tool 45 is operated at locations where the packer 62 is to be set so as to clean the inner wall 34 of the borehole 22. The jetting tool 45 may also operate as the bottom hole assembly 38 enters the liner 24. In this way the inner surface of the liner 24 is cleaned in preparation to be gripped by the spear 48.

[0071] FIG. 3 shows the spear 48 now engaged to grip the inner surface 70 at the top of the liner 24. Weight is set down on the liner 24 so as to keep the valve 50 open to allow fluid flow to the casing cutter 48. Fluid pressure is increased sufficiently to operate the motor 46 and the casing cutter 48 to cut the liner 24 at a desired location. The pressure level is not sufficient to actuate the pulling tool 52. By engaging the spear 48 the liner 24 can be held partially in tension when the cut is made. A cut section of tubular 12 is now formed. This step is optional and may be performed on a separate trip into the well. The length of the cut section 12 is determined from the lengths which has previously been removed and is based on the tools and other matter surrounding the liner 24 which will cause it to stick in the wellbore 16 and prevent its easy removal.

[0072] Once the cut is made, the work string 32 is raised to initially determine if the cut section of tubular 12 is free. This is unlikely and further raising will now extend the mandrel 54 to place the pulling tool 52 at the end of its stroke. Tension will now be applied to the valve 50 and cause its closure. This closes the throughbore and pressure at the pulling tool 52 will now increase sufficiently to set the open hole anchor 56 against the borehole wall 34 at the open hole section 14 of the well bore 16. This is as illustrated in FIG. 4. The spear 48 remains anchored to the cut section of tubular 12.

[0073] With the housing 60 and work string 32 anchored to the borehole wall 34, further increase in pressure will now operate the actuator system 58. Pistons attached to the inner mandrel 54 will move, raising the inner mandrel 54 and placing a large tensile load on the cut section of tubular 12 via the spear 48. This force is multiplied by the action on the plurality of stacked pistons as described hereinbefore. The distance over which the force acts is from the open hole anchor 56 over the mandrel 54 to the connection point at the spear 48. By having the open hole anchor 56 located in the open hole section 14 close to the position of the spear 48, the entire force can be committed to raising the cut section of tubular 12 without causing elongation or torqueing of the mandrel 54.

[0074] The tensile static force on the cut section of tubular 12 should begin to release it from the wellbore 16. The downhole pulling tool 52 will stroke as the mandrel 54 is raised into the housing 60. It is likely that only a small amount of movement of the cut section of tubular 12 will be possible and the tool 52 will only have partially stroked.

[0075] At this point, the tension in the string is reduced so as to cause the valve 50 to open, reducing fluid pressure in the throughbore, which is further reduced by the stopping of pumping at surface. The open hole anchor 56 is released as fluid exits the bladder and the pulling tool 52 is now free to move. The spear 48 remains anchored to the inner surface 70 of the liner 24. The string 32 is raised, which will raise the housing 60 and position of the pulling tool 52 as the mandrel 54 extends to place the pulling tool 52 at the end of its stroke. This is shown in FIG. 5.

[0076] The steps described with reference to FIGS. 4 and 5 are repeated so as to free the cut section of tubular 12. When free, the work string 32 can be raised to recover the cut section of tubular 12. This is shown in FIG. 6. It will be appreciated that, if at any time during the removal of the cut section of tubular it were to stick in the borehole 22, the steps of applying tension to close the valve 50, set the open hole anchor 56 and operate the actuator system 58 of the pulling tool 52, as shown and described with reference to FIGS. 4 and 5, could be repeated to free the cut section of tubular 12. Additionally, if the cut section of tubular were to stick at the location of the heel 20, the open hole anchor 56 could be set against the inner wall 30 of the casing 18, so as to allow the pulling tool 52 to be operated and free the cut section of tubular 12.

[0077] While the method is described with reference to the object being a cut section of tubular, the object may be any component which is stuck in an open hole section of the wellbore. The apparatus and method can be used to move an actuator on a downhole component in the open hole section to perform an operation such as opening and/or closing a valve. Additionally, while the steps of jetting and cutting a tubular are described as occurring on the same trip into the well, these steps may be omitted or performed on separate trips into the well.

[0078] The principle advantage of the present invention is that it provides a method to move an object in an open hole section of a wellbore in which the force applied from a downhole pulling tool is applied directly to the object by anchoring the downhole pulling tool in the open hole section of the wellbore.

[0079] A further advantage of an embodiment of the present invention is that it provides a method of removing a cut section of tubular from an open hole section of a wellbore.

[0080] A yet further advantage of the present invention is that it provides apparatus to move an object in an open hole section of a wellbore in the form of a bottom hole assembly including a downhole pulling tool incorporating an open hole anchor.

[0081] A still further advantage of an embodiment of the present invention is that it provides apparatus for the removal of a cut section of tubular from an open hole section of a wellbore.

[0082] The foregoing description of the invention has been presented for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, further modifications or improvements may be incorporated without departing from the scope of the invention herein intended with the invention being defined within the scope of the claims.