Downhole apparatus

1. Downhole apparatus comprising:

first and second tools for location in a tubing string, the first tool having a first seat of a first diameter and the second tool having a second seat of a second diameter larger than the first diameter, and

first and second activating devices for use in activating the respective first and second tools, the first activating device including a first activating profile having an extended diameter larger than the first diameter and smaller than the second diameter and a retracted diameter smaller than the first diameter, and the second activating device including a second activating profile having an extended diameter larger than the second diameter and a retracted diameter smaller that the first diameter.

2. The apparatus of claim 1 , further comprising a third tool and a third activating device, the third tool having a third seat of a third diameter larger than the second diameter, and the third activating device including a third activating profile having an extended diameter larger than the third diameter and a retracted diameter smaller that the first diameter.

3. The apparatus of claim 1 , further comprising a tubing string.

4. The apparatus of claim 3 , wherein the tubing string is at least one of: a drill string, fishing string, milling string, running string, tool string, casing, liner, or a completion.

5. The apparatus of claim 1 , wherein the tools are one or more of: drill bits, reamers, downhole motors, agitators, MWD tools, LWD tools, downhole steering tools, stabilisers, under-reamers, bypass tools, fishing tools, milling tools, cutting tools, tubing expanders, setting tools, packers, valves, plugs, hangers, perforating guns, or inflow control devices (ICDs).

6. The apparatus of claim 1 , wherein the first and second tools form part of a single tool or apparatus requiring or capable of multiple activations.

7. The apparatus of claim 1 , wherein the tools perform a similar function and are located at spaced locations in the string.

8. The apparatus of claim 1 , wherein the tools perform different functions.

9. The apparatus of claim 1 , wherein at least two activating devices are of the same or similar form.

10. The apparatus of claim 1 , wherein at least two activating devices are of different forms.

11. The apparatus of claim 1 , wherein at least one activating device substantially occludes the string when landed on the respective seat.

12. The apparatus of claim 1 , wherein at least one activating device only partially occludes the string when landed on the respective seat.

13. The apparatus of claim 1 , wherein at least one activating device includes a flow restriction.

14. The apparatus of claim 1 , wherein at least one activating device includes a flow restriction configured to resist wear.

15. The apparatus of claim 1 , wherein at least one activating device includes a flow restriction configured to erode such that the degree of occlusion provided by the restriction reduces over time.

16. The apparatus of claim 1 , wherein at least one activating profile is formed by a member retractable from the extended diameter to define a smaller retracted diameter.

17. The apparatus of claim 1 , wherein at least one activating profile is biased to assume the extended diameter.

18. The apparatus of claim 1 , wherein at least one activating profile is biased to assume the retracted diameter.

19. The apparatus of claim 1 , wherein at least one activating profile is formed by a member radially supported to define the extended diameter, whereby removal of the radial support permits movement of the member to define the retracted diameter.

20. The apparatus of claim 1 , wherein at least one activating profile is formed by a split ring.

21. The apparatus of claim 1 , wherein at least one activating profile is formed by one or more dogs or keys.

22. The apparatus of claim 1 , wherein at least one activating profile is reconfigurable by elevated fluid pressure.

23. The apparatus of claim 1 , wherein at least one activating profile is reconfigurable by mechanical force.

24. The apparatus of claim 1 , comprising at least one release device operable to reconfigure an activating profile.

25. The apparatus of claim 24 , wherein the release device is configured to be passed through the string to reconfigure an activating profile.

26. The apparatus of claim 24 , wherein the activating profile is integral with each, activating device and is contracted out of engagement with the seat by the release device.

27. The apparatus of claim 1 , wherein at least one seat and at least one profile is formed of a non-deformable material.

28. The apparatus of claim 1 , further comprising an activating device catcher.

29. The apparatus of claim 28 , wherein the catcher is located below the first tool.

30. The apparatus of claim 28 , wherein the catcher is arranged to permit fluid bypass around an activating device in the catcher.

31. The apparatus of claim 28 , wherein the catcher no-go with a diameter smaller than the first diameter.

32. The apparatus of claim 28 , wherein the catcher is dimensioned to accommodate multiple activating devices.

33. The apparatus of claim 1 , wherein at least one tool includes a seal for cooperating with the respective activating device.

34. The apparatus of claim 1 , wherein at least one activating device includes a seal for cooperating with the respective tool.

35. The apparatus of claim 1 , wherein at least one activating device and respective seat includes a latch arrangement.

36. A tool activating method comprising:

providing first and second tools in a tubing string, the second tool being located above the first tool in the string, the first tool having a first seat of a first diameter and the second tool having a second seat of a second diameter larger than the first diameter;

providing first and second activating devices for use in activating the respective first and second tools, the first activating device including a first activating profile with an extended diameter larger than the first diameter and smaller than the second diameter and a retracted diameter smaller than the first diameter, and the second activating device having a second activating profile with an extended diameter larger than the second diameter and a retracted diameter smaller that the first diameter;

passing the second activating device through the string such that the second activating profile engages the second seat;

activating the second tool;

retracting the second activating profile from the extended diameter to the retracted diameter; and

passing the second activating device through the second seat and then through the first seat.

37. The method of claim 36 , further comprising:

passing the first activating device through the string such that the first activating device passes through the second tool and the first activating profile then engages the first seat;

activating the first tool;

retracting the first activating profile from the extended diameter to the retracted diameter, and

passing the first activating device through the first seat.

38. The method of claim 37 , comprising passing the first activating device through the string after the second activating device.

39. The method of claim 36 , further comprising:

providing a third tool and a third activating device, the third tool being located in the string above the second tool and having a third seat of a third diameter larger than the second diameter, and the third activating device including a third activating profile having an extended diameter larger than the third diameter and a retracted diameter smaller that the first diameter,

passing the third activating device through the string such that the third activating profile engages the third seat;

activating the third tool;

retracting the third activating profile from the extended diameter to the retracted diameter; and

passing the third activating device through the third seat, then through the second seat, and then through the first seat.