Downhole tool

Abstract

The invention provides a downhole initiator tool (10, 210, 410, 610) for use in initiating a downhole operation, and a method of use. The downhole initiator tool comprises a mandrel (34, 234, 434, 634), an initiator assembly (26, 226, 426, 626), and an anchor assembly (28, 228, 428, 628) mounted on the mandrel. The anchor assembly comprises a radially extendable anchor member (26, 226, 426, 626) for engaging an outer bore structure. The anchor assembly and the mandrel are axially moveable relative to each other in a first axial direction to sequentially extend the anchor member and activate the initiator assembly.

Claims

1. A downhole initiator tool for use in actuating a downhole tool or system, comprising: a mandrel; an initiator assembly; and an anchor assembly mounted on the mandrel and comprising a radially extendable anchor member for engaging an outer bore structure, wherein the anchor assembly and the mandrel are axially moveable relative to each other in a first axial direction to sequentially extend the anchor member and activate the initiator assembly; wherein the anchor assembly and the mandrel are axially moveable relative to each other in the first axial direction in a first relative movement action to cause the anchor member to be extended, and wherein the anchor assembly and the mandrel are axially moveable relative to each other in the same first axial direction in a second relative movement action to cause activation of the initiator assembly; wherein the anchor member is retracted or permitted to be retracted during the second relative movement action.

2. The downhole initiator tool according to claim 1, wherein the creation of an anchor by the anchor member defines a limit or the end of a first movement action.

3. The downhole initiator tool according to claim 2, wherein the anchor assembly and the mandrel are axially moveable relative to each other in the first axial direction in a third relative movement action to cause the anchor member to be retracted.

4. The downhole initiator tool according to claim 2, wherein the anchor assembly and the mandrel are axially moveable relative to each other in a preliminary movement action prior to the first movement action.

5. The downhole initiator tool according to claim 1, wherein the anchor assembly and the mandrel are axially moveable relative to each other in the first axial direction to sequentially extend and retract the anchor member.

6. The downhole initiator tool according to claim 1, comprising an indexing arrangement provided between the mandrel and the anchor assembly.

7. The downhole initiator tool according to claim 6, wherein the indexing arrangement comprises a first indexing portion associated with one of the mandrel and the anchor assembly and comprising an indexing track, and a second indexing portion associated with the other of the mandrel and the anchor assembly and comprising a track follower to be received and move within the indexing track.

8. The downhole initiator tool according to claim 7, wherein one of the first and second indexing portions is rotatably fixed relative to one of the mandrel and the anchor assembly, and the other of the first and second indexing portions is rotatably mounted relative to the other of the mandrel and the anchor assembly.

9. The downhole initiator tool according to claim 1, wherein the downhole initiator tool comprises a provisional anchor assembly associated with the anchor assembly.

10. The downhole initiator tool according to claim 1, wherein the anchor member comprises a slip.

11. The downhole initiator tool according to claim 1, wherein the anchor member comprises a toggle arrangement comprising a toggle anchor portion configured to be pivoted to be radially extended and retracted.

12. The downhole initiator tool according to claim 1, wherein the anchor member comprises a dog arranged to be moved radially within the anchor assembly.

13. The downhole initiator tool according to claim 1, wherein the initiator assembly comprises a hydraulic initiator assembly.

14. The downhole initiator tool according to claim 1, wherein the initiator assembly comprises a valve or valve structure.

15. The downhole initiator tool according to claim 1, wherein the initiator assembly comprises at least first and second components which are caused to move relative to each other to activate the initiator assembly; and wherein a first component is fixed relative to the mandrel, and a second component is fixed, at least temporarily, relative to the anchor assembly, such that relative movement between the anchor assembly and the mandrel provides relative movement between the first and second components of the initiator assembly.

16. The downhole initiator tool according to claim 15, configured such that one of the first and second components of the initiator assembly becomes fixed relative to the anchor assembly after the anchor member has been extended.

17. The downhole initiator tool according to claim 15, wherein the first and second components of the initiator assembly are moveable relative to each other to open a fluid port.

18. The downhole initiator tool according to claim 1, further comprising a control assembly mounted on the mandrel, wherein the control assembly is configured to permit, cause or facilitate the anchor member of the anchor assembly to be positioned in its extended position and/or is configured to permit, cause or facilitate the anchor member of the anchor assembly to be retracted from its extended configuration.

19. The downhole initiator tool according to claim 18, further comprising a releasable connection between the mandrel and the control assembly.

20. The downhole initiator tool according to claim 19, wherein the releasable connection comprises a latch member extending between the control assembly and the mandrel and moveable relative to the control assembly and the mandrel to selectively provide and release the connection therebetween.

21. The downhole initiator tool according to claim 1, wherein the mandrel comprises one or more ports which are initially sealed by a control assembly, and wherein relative movement between the mandrel and the control assembly permits the one or more ports in the mandrel to be opened.

22. The downhole initiator tool according to claim 1, wherein the initiator assembly is configured, when activated, to establish fluid communication between the fluid source and the downhole tool or system, to cause or facilitate actuation of the downhole tool or system.

23. The downhole initiator tool according to claim 1, wherein the initiator assembly, when activated, provides fluid/pressure communication between a wellbore environment and a downhole system, which permits hydrostatic pressure within the wellbore environment to be utilised to actuate the downhole system.

24. A method for downhole actuation of a downhole tool or system, the method comprising: coupling an initiator tool to a downhole tool or system, wherein the initiator tool comprises a mandrel, an anchor assembly and an initiator assembly; positioning the initiator tool in a wellbore; establishing relative axial movement in a first axial direction between the anchor assembly and the mandrel to extend an anchor member of the anchor assembly into engagement with a bore structure; and establishing subsequent relative axial movement in the same first axial direction between the anchor assembly and the mandrel to cause activation of the initiator assembly to actuate the downhole tool or system, wherein activation of the initiator assembly establishes fluid communication between a fluid source and the downhole tool or system to thereby actuate the downhole tool or system.

25. The method according claim 24, comprising causing the anchor member of the anchor assembly to be retracted during or as a result of relative axial movement between the anchor assembly and the mandrel in the first axial direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

(2) FIGS. 1A to 1C diagrammatically illustrate the sequential operation of a downhole tool assembly in accordance with an embodiment of the present invention;

(3) FIG. 2 illustrates a downhole initiator tool in accordance with an embodiment of the present invention;

(4) FIG. 3 is a longitudinal cross-sectional view of the tool of FIG. 2, taken along line 3-3;

(5) FIGS. 4A to 4D are enlarged views of the tool in FIG. 3, in regions 4A to 4D, respectively;

(6) FIG. 5 is an enlarged view of an indexing portion provided on a mandrel of the tool first shown in FIG. 2;

(7) FIG. 6 illustrates the development of track of the indexing portion of FIG. 5 over a full 360 degrees;

(8) FIG. 7 is a perspective view of a portion of a releasable connection assembly, shown isolated from the tool of FIG. 2;

(9) FIGS. 8A to 8F illustrate sequential stages of operation of the tool of FIG. 2;

(10) FIGS. 9A to 9C illustrate sequential stages of operation of a downhole initiator tool in accordance with an alternative embodiment of the present invention;

(11) FIGS. 10A to 10C illustrate sequential stages of operation of a downhole initiator tool in accordance with a further alternative embodiment of the present invention; and

(12) FIGS. 11A to 11D illustrate sequential stages of operation of a downhole initiator tool in accordance with another alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(13) Aspects of the present invention relate to a downhole initiator tool which may be used in various downhole applications for actuating a downhole tool or system. An exemplary embodiment and use of a downhole initiator tool, generally identified by reference numeral 10, is shown in FIGS. 1A to 1C, which illustrate, diagrammatically, the sequential operation of the initiator tool 10 in actuating a sealing apparatus, generally identified by reference numeral 12. The sealing apparatus 12 may be of any suitable form and is configured to provide a seal against a wall 14 of a wellbore 16. The bore 16 may be an open hole or lined bore. In the example shown the sealing apparatus 12 includes a bellows or concertina sealing element 18 which is axially compressed and collapsed to become radially extended to engage the bore wall 14, as will be described in more detail below.

(14) Referring initially to FIG. 1A, the sealing apparatus 12 is connected to the initiator tool 10 via a lower connector 20 on the tool 10, and both the initiator tool 10 and sealing apparatus 12 are deployed into the wellbore 16 on wireline 22. In some cases, for example in deviated wellbores, a wireline tractor may be utilised, although this is not shown for clarity purposes.

(15) The initiator tool 10 includes an anchor assembly 24 which includes a plurality of circumferentially arranged anchor members 26. As will be described in more detail below, the anchor members 26 are operated to be radially extended into engagement with the bore wall 14 to provide a temporary anchor within the wellbore 16.

(16) The initiator tool 10 includes a preliminary anchor assembly 28 which is coupled with and may be considered to form part of the anchor assembly 24. The preliminary anchor assembly 28 includes a number of circumferentially arranged bowed elements 30 which are configured to frictionally engage the bore wall 14.

(17) The initiator tool 10 further includes a mandrel 32 upon which the anchor assembly 24 is mounted, wherein the mandrel 32 and anchor assembly 24 are moveable axially relative to each other. The mandrel carries an upper connector portion 34, such as a rope socket, which facilitates connection with the wireline 22.

(18) The initiator tool 10 further includes an initiator assembly 36, shown in broken outline, which provides actuation of the connected sealing apparatus 12. Any suitable form of initiator assembly may be provided, to establish any suitable form of actuation for the sealing apparatus 12. However, in the present embodiment the initiator assembly 36 is configured to provide hydraulic actuation of the sealing apparatus 12. In particular, the initiator assembly 36, once activated, establishes fluid/pressure communication between the surrounding wellbore fluid with the sealing apparatus 12, permitting wellbore hydrostatic pressure to be used to activate the sealing element 18.

(19) In use, the initiator tool 10 and seal assembly 12 may be deployed into the wellbore 16 to the required depth, as illustrated in FIG. 1A. Following this the mandrel 32 may be pulled via the wireline 22 in the direction of arrow 38, as shown in FIG. 1B. Due to the frictional engagement of the bowed elements 30 with the bore wall 14 the anchor assembly 24 is, to a large extent, held stationary within the wellbore 16, such that a first relative axial movement action is established between the mandrel 32 and the anchor assembly 24. This first relative movement action causes the anchor members 26 to become extended and engage the bore wall 14, providing an anchor within the wellbore 16.

(20) The anchor achieved by the anchor members 26 provides a greater axial resistance than the preliminary anchor assembly 28, and permits the mandrel 32 to be subsequently moved further in the direction of arrow 38, to establish a second relative movement action between the mandrel 32 and the anchor assembly 24, as illustrated in FIG. 1C. Such second relative movement action permits the initiator assembly 36 to become activated, to cause the sealing element 18 of the sealing apparatus 12 to be axially compressed/collapsed and establish a seal against the bore wall 14. Once the initiator assembly 36 has been activated, the anchor members 26 become retracted. This may prevent the anchor members 26 and their anchoring function from interfering with the setting and operation of the sealing apparatus 12.

(21) Accordingly, the initiator tool 10 may be configured to permit the anchor members 26 to be extended, the initiator assembly 36 to be activated, and the anchor members 26 to be subsequently retracted again, all in response to a single movement of the mandrel 32 in the common axial direction illustrated by arrow 38.

(22) In FIGS. 1A to 1C the initiator tool 10 is illustrated in schematic form, to permit the basis of its operation to be briefly illustrated and described. However, various embodiments of the tool 10 are possible, and some exemplary embodiments will be described below with reference to FIGS. 2 to 11.

(23) Reference is initially made to FIG. 2, which illustrates an elevation view of a first embodiment of the tool 10, and FIG. 3 which provides a longitudinal cross-sectional view of the tool in FIG. 2, in combination with FIGS. 4A to 4D which provide enlarged views of regions 4A to 4D of FIG. 3 for clarity purposes.

(24) As described above, the tool 10 includes a mandrel 32 upon which is mounted an anchor assembly 24. In the present embodiment shown the anchor assembly 24 is defined by a slip assembly (still identified by reference numeral 24), wherein the anchor members 26 are provided in the form of slips (still identified by reference numeral 26, and three in the embodiment shown) which are pivotally mounted via respective pin connections 40 to the lower end of a sleeve portion 42 of the slip assembly 24. Each slip 26 is provided in combination with a biasing arrangement 27, as most clearly illustrated in the larger view of FIG. 4C. Each biasing arrangement 27 includes a pin 29 which engages a rear face 31 of a respective slip 26, at an offset distance from the slip pivot axis defined by the pin connections 40. The pin 29 is acted on by a spring 33 in such a manner that a turning moment is created to bias the slips 26 to pivot towards their retracted positions.

(25) The slip assembly 24 includes the preliminary anchor assembly 28 which carries the bowed members 30. FIGS. 4A and 4B provide larger views of the preliminary anchor assembly 28. The preliminary anchor assembly 28 also includes a sleeve member 44 which is coupled, via a threaded connection 46, to the sleeve portion 42 of the slip assembly 24.

(26) The sleeve member 44 of the preliminary anchor assembly 28 includes a number of circumferentially arranged and axially extending surface channels 48, wherein opposing ends 30a, 30b of each bowed member 30 are positioned within a respective channel 48. One end 30a of each bowed member 30 is radially disposed and retained between the sleeve portion 42 and sleeve member 44. The opposite end 30b of each bowed member 30 is radially secured relative to the sleeve member 44 via a threaded retaining ring 50, which is threadedly secured to the outer surface of the sleeve member 44. A number of grub screws 52 extend through the retaining ring 50 from an outer side thereof to engage the ends 30b of the individual bowed members 30 to ensure the members 30 are secured within the preliminary anchor assembly 28.

(27) An upper end of the mandrel 32 is connected to the connector portion 34 which facilitates connection with wireline. Specifically, an upper end of the mandrel 32 includes a threaded portion 54 which is threadedly coupled to the connector portion 34.

(28) A lower end of the mandrel 32 defines the lower connector 20 which facilitates connection with the sealing assembly 12 (FIG. 1).

(29) The tool 10 further includes an indexing arrangement or mechanism 56, which provides a degree of relative movement control between the slip assembly 24 and the mandrel 32. As will be described in further detail below, the indexing arrangement 56 is configured to permit only a predetermined relative movement to be achieved between the slip assembly 24 and the mandrel 32.

(30) The indexing arrangement 56, which can be seen in larger detail in FIG. 4A, comprises a rotatable follower component or ring 58 which is rotatably mounted within an upset end portion 60 of the sleeve member 44 of the preliminary anchor assembly 28. The rotatable follower 58 is mounted to the sleeve member 44 in such a way that the follower 58 is free to rotate relative to the sleeve member 44, and thus relative to the entire slip assembly 24, yet is axially fixed relative to the sleeve member 44 and slip assembly 24.

(31) One axial end 58a of the follower 58 is received within the upset end 60 of the sleeve 44, and is axially retained via a latch ring 62, which may be a split ring, which has teeth for engaging complimentary teeth on the follower 58. The latch ring 62, once locked against the follower 58 via the complimentary teeth, axially secures the follower 58 to the sleeve 44, while permitting relative rotation therebetween, by engagement with an annular shoulder 64 provided on the upset end portion 60. The upset end portion 60 includes a window 66 which allows access to the latch ring 62 with an appropriate tool to permit this to be released to allow the follower 58 and the sleeve 44 to be separated.

(32) The indexing arrangement 56 further includes a pin 68 which extends radially through the follower ring 58 and protrudes from a radially inner surface thereof. The pin 68, which is threadedly secured to the follower ring 58, is partially covered by the upset end 60 of the sleeve 44, which may prevent the pin 68 from being removed.

(33) The pin 68 is engaged within an indexing track 70 formed within the outer surface of the mandrel 32. It should be noted that in FIGS. 3 and 4A the pin 68 appears to sit outside the track 70. However, it will be appreciated by those of skill in the art that the pin 68 sits outside the plane of the cross-section in FIGS. 3 and 4A, but has been included for the purposes of the present description.

(34) An enlarged view of the mandrel 32 in the region of the track 70, with the slip assembly 24 removed, is illustrated in FIG. 5. In the embodiment shown the track 70 extends circumferentially around the mandrel 32 in a defined pattern. The development of the track over a full 360 degrees is illustrated in FIG. 6. The track includes short channel portions 72 and long channel portions 74.

(35) When the mandrel 32 is moved axially relative to the slip assembly 24, the pin 68 will move within the track 70, progressing, or indexing, between the short and long channel portions 72, 74. During such relative movement the follower ring 58 will be caused to rotate. Without any relative rotation the pin 68 would not be able to progress along the track 70. It should be noted, however, that due to the rotatable connection between the follower ring 58 and the sleeve 44, and thus slip assembly 24, there is no requirement for either the mandrel 32 or the slip assembly 24 to be rotated at all. In this respect, the effect of the indexing arrangement 56 may be achieved while only requiring the smaller mass of the follower ring 58 to rotate, rather than the larger mass of either the slip assembly 24 and mandrel 32.

(36) The mandrel 32 includes a number of ports 71 which assist to prevent any hydraulic lock occurring between the mandrel 32 and slip assembly 24.

(37) The mandrel 32 includes a slip supporting region 76 which provides support to the slip members 26. Specifically, the slip supporting region 76 comprises a plurality of planar regions 78 which provide respective planar surfaces on which each slip 26 may be slidably mounted. Such an arrangement may cause the mandrel 32 and the slip assembly 24 to be rotatably fixed together.

(38) The tool 10 further comprises a control assembly 80 mounted on the mandrel 32, below the slip assembly 24, and initially axially separated from the slip assembly 24. The control assembly 80, which is shown in larger view in FIGS. 4C and 4D, is mounted on the mandrel 32 and includes a sleeve structure 82.

(39) The tool 10 also includes a deflector arrangement 81 configured to permit deflection of the slips 26 of the slip assembly 24 radially outwardly during relative movement between the slip assembly 24 and the mandrel 32. In the embodiment shown the deflector arrangement 81 is mounted on, and may be considered to form part of, the control assembly 80, and comprises a plurality (three in the embodiment shown) of slip wedges 84 which are pivotally connected to the sleeve structure 82 via respective pin connections 86. Specifically, the slip wedges 84 are mounted on a wedge ring 83 which forms part of the sleeve structure 82.

(40) The slip assembly 24 and the control assembly 80 (including the deflector arrangement 81) are mounted on the mandrel 32 such that the slips 26 and slip wedges 84 axially face each other, and are in axial alignment. As will be described in further detail below, relative axial movement between the slip assembly 24 and the control assembly 80, caused by movement of the mandrel 32 by a connected wireline, will cause the slips 24 to eventually engage and be deflected by the slip wedges 84, radially outwardly to engage a bore wall.

(41) The mandrel 32 further includes a plurality of mandrel pockets 88, each one in circumferential alignment with a respective slip wedge 84. As will be described in further detail below, following relative axial movement between the mandrel 32 and the control assembly 80, the slip wedges 84 may pivot and drop into the respective mandrel pockets 88, to de-support an associated slip 26 when extended, allowing the slips 26 to become retracted.

(42) The control assembly 80 further comprises a releasable connection arrangement 90 (or latch assembly), which functions to provide a releasable connection between the mandrel 32 and the control assembly 80. The releasable connection arrangement 90, which is shown most clearly in the enlarged view of FIG. 4D, includes a plurality of balls 92, arranged circumferentially around the mandrel 32 at a common axial location. The connection arrangement 90 further comprises an biasing sleeve 94. One axial end 96 of the sleeve 94 is inwardly tapered, and engages the circumferential array of balls 92. A plurality of rods 100 extend from an opposite axial end 98 of the sleeve 94, wherein each rod caries a coil spring 102. FIG. 7 illustrates the assembly of the balls 92, sleeve 94, rods 100 and springs 102, removed from the tool 10. This assembly is located within an annular space 104 defined between the mandrel 32 and the sleeve structure 82 of the control assembly 80, wherein the balls 92 are axially engaged with an end face 93 of the wedge ring 83, and the springs 102 engage an annular shoulder 106 of the sleeve structure. The action of the springs 102 against the shoulder 106 biases the sleeve 94 axially, wherein the tapered surface 96, as a result, biases the balls 92 axially against the end face 93 of the wedge ring 83, and also radially inwardly against the mandrel 32.

(43) The mandrel 32 includes a first annular groove 110 in an outer surface thereof which is arranged to receive the balls 92 when appropriate axial alignment therebetween is achieved, to provide a releasable connection between the control assembly 80 and the mandrel 92, as will be described in more detail below. The mandrel 92 further includes a second, deeper annular groove 112, axially spaced below the first annular groove 110, and also arranged to receive the balls when appropriate axial alignment therebetween is achieved, to provide a more permanent locking between the control assembly 80 and the mandrel 32, as will also be described in more detail below.

(44) As noted above, the tool 10 includes an initiator assembly 36. In the present embodiment this initiator assembly 36 is defined by both the mandrel 32 and the control assembly 80. A larger view of the initiator assembly 36 is provided in FIG. 4D.

(45) The sleeve assembly 82 of the control assembly 80 includes a number of bores 114 which extend axially between respective ports 115 formed in an axial end face 116 of the sleeve structure 82, and an annular chamber 118 defined between the sleeve structure 82 and the mandrel 32. Such an arrangement provides fluid communication of ambient wellbore fluid with the annular chamber 118.

(46) The mandrel 32 includes a central bore 120 at its lower end which will be provided in fluid communication with the sealing apparatus 12 (FIG. 1) when connected therewith. A number of radial bores 122 extend from the central bore to an outer surface of the mandrel 32.

(47) When the initiator assembly 36 is in its deactivated state, as shown in the larger view of FIG. 4D, the mandrel 32 and the control assembly 80 are axially positioned relative to each other such that the radial bores 122 are offset from the annular chamber 118, thus preventing any fluid communication therebetween. Seals 124, 126 are provided on either axial side of the bores 122 to assist with maintaining fluid isolation from the annular chamber 118. As will be described in further detail below, activation of the initiator assembly 36 is achieved by establishing relative axial movement between the mandrel 36 and the control assembly 80, such that the bores 122 become aligned with the annular chamber 118, and permit wellbore pressure to be communicated to a connected sealing apparatus 12 (FIG. 1), or indeed any other tool or system which may be connected to the initiator tool 10.

(48) Reference is now made to FIGS. 8A to 8F which illustrate the sequential operation of the detailed illustrated initiator tool 10 within a wellbore 16. It should be noted that the tool 10 is illustrated in the sequential drawings of FIGS. 8A to 8F without connection to a further tool to be actuated, nor a wireline. This is intended to reflect that the initiator tool 10 could be used to actuate any downhole tool or system, and could be deployed into a wellbore 16 on any suitable deployment mechanism.

(49) The tool 10 is deployed into the wellbore 16 to the desired position, as illustrated in FIG. 8A, with the tool 10 in the configuration shown in FIGS. 2 to 4. While in this configuration the pin 68 of the indexing mechanism 56 is located at position “1” in the track 70, as illustrated in FIG. 6.

(50) When at the desired location within the bore 16, the mandrel 32 is pulled upwardly, with the bowed elements 30 of the preliminary anchor assembly 28 frictionally engaging the bore wall 14 to provide a preliminary axial holding force of the slip assembly 24 relative to the bore wall 14, allowing the mandrel 32 to move axially in the direction of arrow 38 relative to the slip assembly 24. Such relative movement is permitted until the pin 68 of the indexing arrangement 56 becomes located at position “2” of the track 70 (FIG. 6). Such permitted initial relative movement is insufficient to extend the slips 26, as the slips 26 are still maintained at an axial separation distance from the slip wedges 84.

(51) Following this the mandrel 32 may be set back down, in the direction of arrow 130, as shown in FIG. 8C, with the pin 68 of the indexing assembly 56 becoming located at position “3” within the track 70 (FIG. 6). It should be noted that during the progress, or indexing, of the pin 68 from position “1” to “3”, the follower ring 58 is rotated, rather than either the mandrel 32 or the slip assembly 24.

(52) It should be noted that this initial relative movement between the mandrel 32 and slip assembly 24, firstly in the direction of arrow 38 (FIG. 8B), and secondly in the direction of arrow 130 (FIG. 8C), may be considered to define a preliminary relative movement action, in that neither the slips 26 nor the initiator assembly 36 is activated. This preliminary relative movement action must be performed before the initiator tool 10 can be activated. The requirement or ability to perform the preliminary movement action may provide an operator with numerous advantages. For example, this may prevent an inadvertent activation of the initiator tool 10, for example due to an upward pull on the mandrel 32 being required for repositioning of the entire tool 10, for assisting in establishing depth correlation or the like.

(53) As illustrated in FIG. 8D, a subsequent upward pull on the mandrel 32 establishes a further relative axial movement between the mandrel 32 and the slip assembly 24, in the direction of arrow 38, in this case causing the pin 68 of the indexing assembly to enter the long channel portion 74 of the indexing track 70, as shown in FIG. 6. Accordingly, relative axial movement may be permitted beyond that previously achievable, allowing the slips 26 to engage and be deflected radially outwardly by the slip wedges 84 to establish an anchor against the bore wall 14. At this point the pin 68 of the indexing arrangement 56 is located at position “4” within the indexing track 70, as illustrated in FIG. 6. This movement to reposition the pin 68 from position “3” to “4” (FIG. 6) may be considered to be a first relative movement action.

(54) When the anchor is established, continued pulling on the mandrel 32 in the direction of arrow 38 will generate an increasing axial force against the control assembly 80, which will, ultimately, act against the balls 92 of the releasable connection arrangement 90 via the wedge ring 83. This will cause the balls 92 to be urged radially outwardly from the first recess 110 in the mandrel 32, thus axially loading the sleeve 94 via its tapered end face 96. When this axial load applied via the balls 92 exceeds the axial force in the opposite direction established by the springs 102, the balls 92 will become released from the first recess 110, releasing the axial connection between the control assembly 80 and the mandrel 32. Accordingly, the force of the springs may dictate the required axial force necessary to release the connection. When the connection is released, the mandrel 32 and the control assembly 80 may now be moveable axially relative to each other, as shown in FIG. 8E, such that the bores 122 of the mandrel 32 may become aligned with the annular chamber 118, establishing fluid communication between the surrounding wellbore fluid and mandrel bore 120, and thus activating the initiator assembly 36. At this point any connected tool or system may begin to be actuated.

(55) Continued relative movement between the mandrel 32 and the slip assembly 24 may eventually cause the slip wedges 84 to become fully aligned with the mandrel pockets 88, allowing the slip wedges 84 to collapse into the pockets 88 and slips 26 to be retracted and release the anchor. At this point the pin 68 of the indexing arrangement 56 will be located at position “5” within the indexing track 70, as shown in FIG. 6. The relative movement between the mandrel 32 and the slip assembly 24 to reposition the pin 68 from position “4” to “5” may be considered to be a second relative movement action.

(56) At the point when the slips 26 become retracted, the balls 92 of the releasable connection arrangement 90 become aligned and received within the second deeper annular groove 112. The depth of this groove 112 is such that the balls 92 cannot be radially displaced by an applied axial force, and as such the initiator tool 10 becomes locked-out.

(57) An alternative embodiment of an initiator tool, identified by reference number 210, will now be described with reference to FIGS. 9A to 9C, which are sequential cross-sectional views of the tool 210 during operation. The tool 210 shares many similar features and functions in a very similar manner to the tool 10 first shown in FIG. 2, and as such like features share like reference numerals, incremented by 200. In view of the similarities between tool 210 and tool 10, only the principal differences will be highlighted.

(58) In this case the tool 210 includes a mandrel 232 upon which is mounted an anchor assembly 224 which carries a number of anchor members 226. In this embodiment the anchor members 226 each comprise a toggle arrangement including a toggle anchor portion 226a, an activator arm portion 226b and a toggle ring 226c. One end of each toggle anchor portion 226a is pivotally mounted to a sleeve portion 242 of the anchor assembly 224. An opposite end of each toggle anchor portion 226a is pivotally connected to one end of a respective activator arm portion 226b. Each opposite end of the activator arm portions 226b are pivotally connected to the toggle ring 226c. As will be described in more detail below, upon application of an axial force against the toggle ring 226c the toggle anchor portion 226a is caused to be radially extended.

(59) The tool 210 further comprises a preliminary anchor assembly 228 which is similar in form and function to anchor assembly 28 of tool 10, and as such no further detailed description will be given.

(60) The tool 210 further comprises an upper connector portion 234 for facilitating connection to wireline, for example, and a lower connector portion 220 for facilitating connection to, for example, a tool to be initiated or operated by the initiator tool 210.

(61) The tool 210 further comprises an indexing arrangement or mechanism 256 which is similar in form and function to the indexing arrangement 56 of tool 10, and as such no further detailed description will be given.

(62) The tool 210 further comprises an initiator assembly 236 which is similar in form and function to the initiator assembly 36 of tool 10, and as such no further detailed description will be given.

(63) The tool 210 further comprises a deflector arrangement 281. However, in this present embodiment the deflector arrangement 281 is defined by an annular face or shoulder 130 provided on a control assembly 280 which is mounted on the mandrel. The control assembly 280 is otherwise similar in form and function to the control assembly 80 of tool 10, and as such no further detailed description will be given, except to confirm that the control assembly 280 of tool 210 also comprises a releasable connection arrangement 290, similar to the releasable connection arrangement 90 of the tool 10.

(64) In use, the tool 210 may be deployed into a wellbore (not shown) in the initial configuration of FIG. 9A. Deployment may be achieved on wireline (also not shown) connected via connector 234, and the tool 210 may carry a downhole tool (also not shown) to be activated via connector 220. When initiation is required an upward pulling force may be applied on the mandrel 232 via connector 234 (for example by an upward pull on wireline) in the direction of arrow 238, wherein the anchor assembly 224 may be held substantially stationary relative to the wellbore by action of the preliminary anchor assembly 228 acting against the bore wall, permitting relative movement between the mandrel 232 and the anchor assembly 224 to be achieved. In a similar manner to tool 10 described above, a preliminary movement sequence may be required to be performed, controlled by the indexing arrangement 256, before the mandrel 232 and anchor assembly 224 can be sufficiently moved relative to each other to engage the toggle ring 226c against the shoulder 130 of the deflector arrangement 281, as illustrated in FIG. 9B. Continued relative movement between the mandrel 232 and the anchor assembly 224 may cause the toggle arrangements 226 to be activated and the anchor toggle portions 226a to be pivoted and radially extended to engage and grip an outer bore wall.

(65) Once an anchor is established by the toggle arrangements 226, further axial force applied between the mandrel 232 and the anchor assembly 224 will cause the releasable connection 290 to become loaded, eventually releasing the connection between the control assembly 280 and the mandrel, and allowing the initiator assembly 236 to become activated, as shown in FIG. 9C. Also, following release of the connection between the control assembly 280 and the mandrel 232, the toggle arrangements 226 may be retracted again to remove any anchor. In a similar manner as in tool 10, respective biasing arrangements 227 act against each toggle arrangement 226 to assist in retraction.

(66) An alternative embodiment of an initiator tool, identified by reference number 410, will now be described with reference to FIGS. 10A to 10C, which are sequential cross-sectional views of the tool 410 during operation. The tool 410 shares many similar features and functions in a very similar manner to the tool 10 first shown in FIG. 2, and as such like features share like reference numerals, incremented by 400. In view of the similarities between tool 410 and tool 10, only the principal differences will be highlighted.

(67) In this case the tool 410 includes a mandrel 432 upon which is mounted an anchor assembly 424 which carries a number of anchor members 426. In this embodiment the anchor members 426 each comprise a dog radially mounted in a respective slot in a sleeve portion 442 of the anchor assembly 424.

(68) The tool 410 further comprises a preliminary anchor assembly 428 which is similar in form and function to anchor assembly 28 of tool 10, and as such no further detailed description will be given.

(69) The tool 410 further comprises an upper connector portion 434 for facilitating connection to wireline, for example, and a lower connector portion 420 for facilitating connection to, for example, a tool to be initiated or operated by the initiator tool 410.

(70) The tool 410 further comprises an indexing arrangement or mechanism 456 which is similar in form and function to the indexing arrangement 56 of tool 10, and as such no further detailed description will be given.

(71) The tool 410 further comprises an initiator assembly 436 which is similar in form and function to the initiator assembly 36 of tool 10, and as such no further detailed description will be given.

(72) The tool 410 further comprises a deflector arrangement 481. However, in this present embodiment the deflector arrangement 481 is defined by an annular protrusion 132 integrally formed on an outer surface of the mandrel 432, wherein the annular protrusion comprises opposing ramp profiles 134, 136. As will be described in more detail below, the dogs 426 are radially extended when axially aligned with the annular protrusion 132.

(73) The tool 410 further comprise a control assembly 480 which is mounted on the mandrel 432, wherein the control assembly 480 is similar in form and function to the control assembly 80 of tool 10, and as such no further detailed description will be given, except to indicate that the control assembly 480 comprises an annular shoulder 140, and to confirm that the control assembly 480 of tool 410 also comprises a releasable connection arrangement 490, similar to the releasable connection arrangement 90 of the tool 10.

(74) In use, the tool 410 may be deployed into a wellbore (not shown) in the initial configuration of FIG. 10A. Deployment may be achieved on wireline (also not shown) connected via connector 434, and the tool 410 may carry a downhole tool (also not shown) to be activated via connector 420. When initiation is required an upward pulling force may be applied on the mandrel 432 via connector 434 (for example by an upward pull on wireline) in the direction of arrow 438, wherein the anchor assembly 424 may be held substantially stationary relative to the wellbore by action of the preliminary anchor assembly 428 acting against the bore wall, permitting relative movement between the mandrel 432 and the anchor assembly 424 to be achieved. In a similar manner to tool 10 described above, a preliminary movement sequence may be required to be performed, controlled by the indexing arrangement 456, before the mandrel 432 and anchor assembly 424 can be sufficiently moved relative to each other to align the dogs 426 with the annular protrusion 132, permitting the dogs 426 to radially extended, as shown in FIG. 10B. When extended the dogs 426 may grip an outer bore structure, such as a bore wall, and/or be received within a suitable profile.

(75) When in the configuration shown in FIG. 10B, an end of the sleeve 442 of the anchor assembly 424 abuts the annular shoulder 140 of the control assembly 480. When the releasable connection 490 is configured to provide a connection between the control assembly 480 and the mandrel 432, as in FIG. 10B, the control assembly 480 functions to limit relative movement between the anchor assembly 424 and the mandrel 432. Such a limit is provided at a location in which the dogs 426 are aligned with the annular protrusion 132 and thus extended.

(76) Once an anchor is established by the dogs 426, further axial force applied between the mandrel 432 and the anchor assembly 424 will cause the releasable connection 490 to become loaded, via the engagement between the sleeve 442 of the anchor assembly 424 and the annular shoulder 140 of the control assembly 480, eventually releasing the connection between the control assembly 480 and the mandrel 432, and allowing the initiator assembly 436 to become activated, as shown in FIG. 10C.

(77) Following release of the connection between the control assembly 480 and the mandrel 432, the mandrel 432 may be free to move further in the same direction relative to the anchor assembly 424, causing misalignment between the dogs 426 and the annular protrusion 132, permitting the dogs 426 to be retracted, as shown in FIG. 10C.

(78) A further alternative embodiment of an initiator tool, identified by reference number 610, will now be described with reference to FIGS. 11A to 11D, which are sequential cross-sectional views of the tool 610 during operation. The tool 610 shares many similar features and functions in a very similar manner to the tool 10 first shown in FIG. 2, and as such like features share like reference numerals, incremented by 600. In view of the similarities between tool 610 and tool 10, only the principal differences will be highlighted.

(79) In this case the tool 610 includes a mandrel 632 upon which is mounted an anchor assembly 624 which carries a number of anchor members 626. In this embodiment the anchor members 626 each comprise a dog radially mounted in a respective slot in a sleeve portion 642 of the anchor assembly 624. Each dog 626 includes a profile 150 on a radially outwardly facing surface thereof.

(80) The tool 610 further comprises a preliminary anchor assembly 628 which is similar in form and function to anchor assembly 28 of tool 10, and as such no further detailed description will be given.

(81) The tool 610 further comprises an upper connector portion 634 for facilitating connection to wireline, for example, and a lower connector portion 620 for facilitating connection to, for example, a tool to be initiated or operated by the initiator tool 610.

(82) The tool 610 further comprises an indexing arrangement or mechanism 656 which is similar in form and function to the indexing arrangement 56 of tool 10, and as such no further detailed description will be given.

(83) The tool 610 further comprises an initiator assembly 636 which is similar in form and function to the initiator assembly 36 of tool 10, and as such no further detailed description will be given.

(84) The tool 610 further comprises a deflector arrangement 681. However, in this present embodiment the deflector arrangement 681 is defined by a number of spring elements 152 mounted on an outer surface of the mandrel 632. As will be described in more detail below, each dog 626 is radially extended when axially aligned with a respective spring element 152.

(85) The tool 610 further comprise a control assembly 680 which is mounted on the mandrel 632, wherein the control assembly 680 is similar in form and function to the control assembly 80 of tool 10, and as such no further detailed description will be given, except to indicate that the control assembly 680 comprises an annular shoulder 154, and to confirm that the control assembly 680 of tool 610 also comprises a releasable connection arrangement 690, similar to the releasable connection arrangement 90 of the tool 10.

(86) In use, the tool 610 may be deployed into a wellbore (not shown) in the initial configuration of FIG. 11A. Deployment may be achieved on wireline (also not shown) connected via connector 634, and the tool 610 may carry a downhole tool (also not shown) to be activated via connector 620. When initiation is required an upward pulling force may be applied on the mandrel 632 via connector 634 (for example by an upward pull on wireline) in the direction of arrow 638, wherein the anchor assembly 624 may be held substantially stationary relative to the wellbore by action of the preliminary anchor assembly 628 acting against the bore wall, permitting relative movement between the mandrel 632 and the anchor assembly 624 to be achieved. In a similar manner to tool 10 described above, a preliminary movement sequence may be required to be performed, controlled by the indexing arrangement 656, before the mandrel 632 and anchor assembly 624 can be sufficiently moved relative to each other to axially align the dogs 626 with the spring elements 152, permitting the dogs 626 to be radially extended, as shown in FIG. 11B.

(87) FIG. 11B illustrates the tool 610 positioned within an outer bore structure 160 (only a portion of the outer bore structure is illustrated) which includes a profile section 162. The profile section 162 compliments the profiles 150 of the dogs 626. As shown in FIG. 11B, the tool 610 is initially positioned relative to the outer bore structure 160 such that the dogs 626 are axially misaligned from the profile section 162 of the outer bore structure 160. In such a situation, the dogs 626 may not be fully extended and press against the radially outward bias of the spring elements 152. Movement of the entire tool 610 in the direction of arrow 638 will eventually align the dogs 626 with the profile section 162, as shown in FIG. 11C, permitting the dogs 626 to be radially extended by action of the spring elements 152, and allowing the profiles 150 of the dogs 626 to engage the complimentary profile section 162 and establish an anchor. Such an arrangement may allow the tool 610 to be set or anchored at a desired location, for example to ensure correct positioning of a further downhole tool to be initiated.

(88) As the dogs 626 are extended on spring elements 152, the dogs may be radially compliant, and may be moved or deflected in a radial direction until such time as the profile section 162 is engaged. In some embodiments (not illustrated), a number of different profile sections may be provided in the outer bore structure 160, wherein the dogs 626 are configured only to match one of the profile sections. In such an arrangement as the tool 610 is moved relative to the outer bore structure 160 the dogs may simply be deflected by non-matching profiles until the matching profile is reached. This may provide a degree of downhole addressability, in that the ultimate location of the downhole initiator tool 610 may be selected in accordance with the type or form of dogs 626 utilised. In this respect, the dogs 626 may be readily interchangeably to utilise a number of different profiles 150.

(89) When in the configuration shown in FIGS. 11B and 11C, an end of the sleeve 642 of the anchor assembly 624 abuts the annular shoulder 154 of the control assembly 680. When the releasable connection 690 is configured to provide a connection between the control assembly 680 and the mandrel 432, as in FIGS. 11B and 11C, the control assembly 680 functions to limit relative movement between the anchor assembly 624 and the mandrel 632. Such a limit is provided at a location in which the dogs 626 are axially aligned with the spring elements 152 and thus extended.

(90) Once an anchor is established by the dogs 626, as shown in FIG. 11C, further axial force applied between the mandrel 632 and the anchor assembly 624 will cause the releasable connection 690 to become loaded, via the engagement between the sleeve 642 of the anchor assembly 624 and the annular shoulder 154 of the control assembly 680, eventually releasing the connection between the control assembly 680 and the mandrel 632, and allowing the initiator assembly 636 to become activated, as shown in FIG. 11D.

(91) Following release of the connection between the control assembly 680 and the mandrel 632, the mandrel 632 may be free to move further in the same direction relative to the anchor assembly 624, causing misalignment between the dogs 626 and the spring elements 152, permitting the dogs 626 to be retracted, as shown in FIG. 100.

(92) It should be understood that the embodiment described herein is merely exemplary and that various modifications may be made thereto without departing from the scope of the invention. For example, the releasable connection, such as connection 90 shown in FIG. 3, may be provided in isolation from other features in the illustrated embodiments, and may function to provide a latch assembly according to an embodiment of an aspect of the present invention. Also, the indexing arrangement, such as arrangement 56 illustrated in FIG. 3, may be provided in isolation form other features in the illustrated embodiments, and may function as an indexing apparatus according to an embodiment of an aspect of the present invention.

(93) The invention provides a downhole initiator tool for use in initiating a downhole operation, and a method of use. The downhole initiator tool comprises a mandrel, an initiator assembly, and an anchor assembly mounted on the mandrel. The anchor assembly comprises a radially extendable anchor member for engaging an outer bore structure. The anchor assembly and the mandrel are axially moveable relative to each other in a first axial direction to sequentially extend the anchor member and activate the initiator assembly.

(94) The invention extends to combinations of features other than those expressly claimed herein.