CA2429459A1

CA2429459A1 - Adjustable stabiliser for directional drilling

Info

Publication number: CA2429459A1
Application number: CA002429459A
Authority: CA
Inventors: Mark Alexander Russell; Andrew Ollerenshaw
Original assignee: Individual
Current assignee: Toolbox Drilling Solutions Ltd
Priority date: 2000-11-20
Filing date: 2001-11-15
Publication date: 2002-05-23
Anticipated expiration: 2021-11-15
Also published as: ATE373159T1; DE60130483T2; DE60130483D1; AU2002218396A1; GB0028243D0; WO2002040823A1; GB2369136A; CA2429459C; EP1346128A1; EP1346128B1

Abstract

A stabiliser (10) has a body (12) having a through-bore (16). A mandrel (14), also having a through-bore (20), is axially slidable in the body bore to actuate and de-actuate the tool. A step (64) in the body defines annular chambers (102, 104) between the mandrel and body on either side of the step. A control piston (18) in the mandrel alternately directs drilling mud pumped under pressure along said body bore and mandrel bore to the chambers to drive the mandrel hydraulically to actuate and de-actuate the tool. The control piston has a through-bore (46) and is slidable in the mandrel bore against the force of a return spring (40) by drilling mud pressure from a low-pressure position to a pressure position. The pressure position is alternately one of an actuate position (a) and a de-actuate position (b), axially spaced along the mandrel bore from said actuate position.

Claims

1. A down-hole tool comprising:
a body having a through-bore;
a mandrel, being axially slidable in the body bore to actuate and de-actuate the tool; and a valve to control hydraulically the movement of the mandrel by drilling mud pumped under pressure along said body bore.

2. A tool as claimed in claim 1, wherein said valve controls the drilling mud to drive the mandrel hydraulically both to actuate and de-actuate the tool.

3. A tool as claimed in claim 1 or 2, wherein the mandrel has a through bore and the valve comprises a control piston slidable in the mandrel bore, against the force of a return spring, by drilling mud pressure from a low-pressure position to a pressure position.

4. A tool as claimed in claim 3, wherein, said pressure position is alternately one of an actuate position and a de-actuate position axially spaced along the mandrel bore from said actuate position, the tool being actuated by mud pressure when the piston is in said actuate position and de-actuated when in said de-actuate position.

5. A tool as claimed in claim 4, in which the actuate position is between the de-actuate and low-pressure positions of the piston.

6, A tool as claimed in claim 4 or 5, when dependent on claim 2, in which a return step is formed in the body and mandrel to define annular chambers between them on either side of the return step, one chambers when pressurised with mud, serving to actuate the tool while the other serves to de-actuate the tool.

7. A tool as claimed in claim 6, in which said control piston has an axially disposed passage and a seal against the mandrel at both ends of the passage, the mandrel having two ports communicating each of said annular chambers with the mandrel bore and an intermediate port venting said passage, the piston in the actuate position connecting one chamber with the passage and the other chamber with the piston bore beyond the seals, and vice-versa in said de-actuate position.

8. A tool as claimed in any of claims 3 to 7, in which the mandrel bore and piston are stepped, the annular piston chamber formed by said step between them being vented so that pressure of drilling mud in the body moves the piston along the mandrel to close said piston chamber,

9. A tool as claimed in any of claims 3 to 8, in which the piston and mandrel between them define a barrel cam so that the piston rotates on axial movement thereof relative to the mandrel, the cam permitting different strokes of the piston in dependence upon the angular position of the piston in the mandrel.

10. A tool as claimed in claim 9, in which the piston and mandrel have inter-digitating castellations which, when they oppose one another in a first angular position of the piston with respect to the mandrel, as determined by the barrel cam, permit the piston to move to one of said actuate and de-actuate positions and, when they inter-digitate, permit the piston to move to the other of said actuate and de-actuate positions.

11. A tool as claim in claim 10, in which the barrel cam comprises a pin in a track and the track is arranged so that rotation. of the piston with respect to the mandrel is complete before the castellations engage one another.

12. A tool as claimed in claim 11, in which the track is on the piston and the pin is on the mandrel.

13. A tool as claimed in claim 11 or 12, in which the track is so arranged that the castellations abut in either the actuate or de-actuate positions and transmit axial hydraulic forces between the piston and mandrel before the pin reaches the end of the track.

14. A tool as claimed in claim 6, or any of claims 7 to 13 when dependent on claim 6, in which the return step is inward of the body and comprises two rings interconnected and captivating between them ring sectors received in an annular groove in the body.

15. A tool as claimed in claims 7 and 14, in which a passage through the return step is vented and.
communicates with said intermediate port of the mandrel, the mandrel being sealed to the return step on either side of said passage and intermediate port.

16. A tool as claimed in claim 6, or any of claims 7 to 15 when dependent on claim 6, in which the diameter of the chambers are different, the chamber serving to actuate the tool when pressurised having the larger diameter.

17. A tool as claimed in claim 6, or any of claims 7 to 16 when dependent on claim 6, in which the diameter of the mandrel in the body on the sides of the chambers remote from the return step is larger on the side where hydraulic pressure moves the mandrel to actuate the tool.

18. A tool as claimed in any preceding claim, in which a choke is activated when the tool is actuated, such activation to change the pressure drop of the drilling mud across the tool so as to signal the states of actuation of the tool.

19. A tool as claimed in claim 18, in which the piston carries a piston restrictor plate across the piston bore in face to face contact with a mandrel restrictor plate, the restrictor plates being angularly fixed with respect to the piston and mandrel respectively and restricting mud flow through the tool in dependence upon their relative angular position.

20. A tool as claimed in claim 19, in which the mandrel restrictor plate is angularly fixed with respect to the body, the body being angularly fixed with respect of the mandrel.

21. A tool as claimed in claim 19 or 20, in which the restrictor plates have a central aperture in register with one another and alternating sector spaces and sector lobes so that, when the lobes on the piston and mandrel plates are in register with one another, mud flows through both the central aperture and spaces, and when the lobes and spaces are in register, mud flows through the central aperture.

22. A tool as claimed in claim 1, or in any of claims 3 to 21 when not dependent on claim 2, in which said mandrel is moved to actuate the tool by hydraulic pressure of said drilling mud when said valve permits bleeding of a bleed chamber.

23. A tool as claimed in claim 22, in which said mandrel is moved to de-actuate the tool, on release of said hydraulic pressure, by a mandrel return spring.

24. A tool as claimed in claim 22 or 23, in which said bleed chamber is formed by a step between the mandrel and body.

25. A tool as claimed in claims 3 and 24, in which said piston serves to open and close a port between said bleed chamber and the body bore.

26. A tool as claimed in claims 4 and 25, in which said piston, when it moves from said low-pressure position to said pressure position, only opens said port when it moves to said actuate position.

27. A tool as claimed in claim 18 and claim 25 or 26, in which said body defines, with the ends of said piston and mandrel, a valve chamber, said choke comprising a path between said piston and body which is opened when said piston moves to said actuate position and the mandrel moves to actuate the tool, and which is restricted when the piston moves to said de-actuate position.

28. A stabiliser comprising a tool as claimed in any preceding claim, and members radially disposed in the body and pressed outwardly by the mandrel during actuation of the tool to increase the effective diameter of the stabiliser.

29. A drill string comprising a drill bit, and a near-bit stabiliser as claimed in claim 28.

30. A drill string stabiliser substantially as hereinbefore described with reference to the drawings.