DOWNHOLE DEVICE

• US 20110198126A1
• Filed: 09/04/2008
• Published: 08/18/2011
• Est. Priority Date: 09/04/2007
• Status: Active Grant

• Current Assignee: George Swietlik, Stephen John Mcloughlin
• Original Assignee: George Swietlik, Stephen John Mcloughlin
• Inventors: McLoughlin, Stephen John, Swietlik, George
• Granted Patent: US 9,109,410 B2
• Time in Patent Office: Days
• US Class Current: 175/55
• CPC Class Codes: E21B 17/07 Telescoping joints for varying drill string lengths; Shock absorbers
• CPC Class Codes: E21B 17/073 with axial rotation

Abstract

A downhole device comprising a mandrel (21) suitable for connection to a drilling assembly (3), a housing (22) surrounding said mandrel said housing being suitable for connection to the alternate end of a drilling assembly and a compensating mechanism (25) configured to adjust an axial force applied to said mandrel by changing the relative position of the mandrel with respect to the housing.

Claims

1. A downhole device comprising a mandrel suitable for connection to a drilling assembly, a housing surrounding said mandrel said housing being suitable for connection to the alternate end of a drilling assembly and a compensating mechanism configured to adjust an axial force applied to said mandrel by changing the relative position of the mandrel with respect to the housing.

2. A device according to claim 1, wherein said compensating mechanism is configured to adjust an axial force applied to said mandrel when said mandrel rotates with respect to said housing.

3. A device according to either of claim 1 or 2, wherein said compensating mechanism further comprises a primary resilient damping means and a secondary damping means which is variable in situ to alter the natural frequencies of the device in order to responsively damp oscillatory motion over one or both of a range of input frequencies and amplitudes.

4. A device according to claim 3, wherein the secondary damping means comprises fluid displacement means.

5. A device according to any preceding claim, wherein said compensating mechanism decouples and adjusts simultaneously for axial and torsional compliance in response to varying dynamic and inertial forces generated by the drilling process.

6. A device according to claim 5, wherein said compensating mechanism comprises a sleeve element, contained within a housing, said sleeve element being axially encapsulated and subjected to compression by at least one pre-loaded compression spring providing concurrent axial and torsional pre-load within said housing, said control assembly being configured such that when said compression spring means is overcome said sleeve element is rotated and axial translation occurs with respect to mandrel and housing.

7. A device according to claim 6, wherein the sleeve rotational translation has in excess of 90°

freedom of motion.

8. A device according to either of claim 6 or 7, the compensating mechanism being adapted such that device can be calibrated or accommodated to the specific drilling conditions by varying its emplacement along the drilling assembly or drillstring.

9. A device according to any preceding claim, further comprising sensors and instrumentation configured to iteratively, adaptively or otherwise intelligently control the damping of the device.

10. A device according to claim 9, wherein said sensors and instrumentation are further adapted to allow for inclusion and integration of both proximally and distally mounted external sensor information which information may be input via downlink communications, hardwire, electro-magnetic telemetry or other means for the purposes of identifying and informing on state changes in drillstring harmonic frequencies and amplitudes.

11. A device according to any preceding claim, wherein the compensating mechanism comprises active hydraulic damping using magneto-rheological fluid, said active hydraulic damping being adapted to provide axial and torsional compliance means at least at a second specific harmonic frequency.

12. A device according to claim 11, wherein the variable active hydraulic damping comprises a first and a second reservoir containing hydraulic fluid, and means to control damping by controlling the transfer of fluids between these two reservoirs.

13. A device according to claim 12, wherein the active hydraulic damping comprises a plurality of fluid transfer conduits and said fluid transfer is effected through said conduits.

14. A device according to any of claims 11 to 13, further comprising rare earth magnet means, configured to alter properties of the magneto-rheological fluid.

15. A device according to any of claims 11 to 13, further comprising electro-magnetic coil assembly means configured to alter properties of the magneto-rheological fluid.

16. A device according to any preceding claim, further comprising stabilizer means.

17. A device according to any preceding claim, further comprising a non-rotatable element configured to be in contact with the borehole.

18. A method of compensating for unwanted local variations in the drilling process, the method comprising:

providing a mandrel suitable for connection to a drilling assembly,

providing a housing, suitable for connection to the alternate end of a drilling assembly and surrounding said mandrel; and

adjusting an axial force applied to said mandrel by changing the relative position of the mandrel with respect to the housing.

19. A method according to claim 20, wherein the axial force is adjusted by rotating the mandrel with respect to the housing.

20. A method according to either of claim 18 or 19, further configured to damp vibrations by controlling hydraulic fluid flow within channels by means of simultaneous axial and rotational translation of an element of the device.

21. A method according to claim 20, whereby the hydraulic fluid characteristics are altered through variable application of a magnetic field.