Downhole tool

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.