Downhole tool

• US 7,975,392 B1
• Filed: 03/10/2010
• Issued: 07/12/2011
• Est. Priority Date: 03/10/2010
• Status: Active Grant

• Current Assignee: National Oilwell Varco LP (NOV, Inc.)
• Original Assignee: National Oilwell Varco LP (NOV, Inc.)
• Inventors: Spaulding, Paul D.
• Primary Examiner(s): Guadalupe; Yaritza
• Application Number:
  US12/720,758
• Time in Patent Office: 489 Days
• Field of Search: 333/02, 333/03, 333/13, 333/18, 333/21, 333/22, 333/23, 335/42, 335/44
• US Class Current: 33/302
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: F16F 15/002 characterised by the control method or circuitry control of mechanical oscillations per se G05D19/00

Abstract

Tools and methods for subsurface operations. Circuit arrangements providing a damping effect against undesired vibration effects on inertial data signals derived from inertial sensors disposed in a downhole tool.

Claims

1. A tool for use in a downhole operation, comprising:

at least one inertial sensor configured to provide inertial data signals during a downhole operation;

wherein the inertial data signals are affected by undesired vibration;

an electronic circuit configured to provide a damping effect against the undesired vibration effects on the inertial data signals;

wherein the electronic circuit is configured to magnify a capacitance effect to compensate against the undesired vibration effects on the inertial data signals.

2. A tool as claimed in claim 1, wherein the electronic circuit is configured to actively source or sink current to/from ground to magnify the capacitance effect of the circuit.

3. A tool as claimed in claim 2, wherein the electronic circuit is configured to provide a variable damping effect.

4. A tool as claimed in claim 3, wherein the electronic circuit is configured to provide the damping effect when the tool is disposed downhole.

5. A tool as claimed in claim 4, wherein the electronic circuit is configured to maintain an output DC voltage substantially within a capture range despite vibration on the inertial sensor.

6. A tool as claimed in claim 5, wherein the tool comprises three mutually orthogonal inertial sensors, each sensor configured to provide inertial data signals during a downhole operation.

7. A tool as claimed in claim 6, wherein each sensor is linked to an electronic circuit configured to provide a damping effect against undesired vibration effects on the inertial data signals.

8. A tool as claimed in claim 7, wherein each electronic circuit is configured to actively source or sink current to/from ground to magnify the capacitance effect of the circuit.

9. A tool as claimed in claim 8, wherein each electronic circuit is configured to provide a variable damping effect.

10. A tool as claimed in claim 9, wherein each electronic circuit is configured to provide the damping effect when the tool is disposed downhole.

11. A tool as claimed in claim 10, wherein each electronic circuit is configured to maintain an output DC voltage substantially within a capture range despite vibration on the inertial sensor.

12. A method of operating a downhole tool, comprising:

obtaining inertial data signals during a downhole operation using at least one inertial sensor disposed on the downhole tool, wherein the inertial data signals are affected by undesired vibration; and

providing a damping effect against the undesired vibration effects on the inertial data signals using an electronic circuit disposed on the downhole tool, the circuit configured to magnify a capacitance effect to compensate against the undesired vibration effects on the inertial data signals.

13. The method as claimed in claim 12, further comprising configuring the electronic circuit to actively source or sink current to/from ground to magnify the capacitance effect of the circuit.

14. The method as claimed in claim 13, further comprising configuring the electronic circuit to provide a variable damping effect.

15. The method as claimed in claim 14, further comprising configuring the electronic circuit to provide the damping effect when the tool is disposed downhole.

16. The method as claimed in claim 15, further comprising configuring the electronic circuit to maintain an output DC voltage substantially within a capture range despite vibration on the inertial sensor.

17. The method as claimed in claim 12, wherein the tool comprises three mutually orthogonal inertial sensors, each sensor configured to provide inertial data signals during a downhole operation.

18. The method as claimed in claim 17, wherein each sensor is linked to an electronic circuit configured to provide a damping effect against undesired vibration effects on the inertial data signals.

19. The method as claimed in claim 18, further comprising configuring each electronic circuit to actively source or sink current to/from ground to magnify the capacitance effect of the circuit.

20. The method as claimed in claim 19, wherein each electronic circuit is configured to provide a variable damping effect.

21. The method as claimed in claim 20, wherein each electronic circuit is configured to provide the damping effect when the tool is disposed downhole.

22. The method as claimed in claim 21, wherein each electronic circuit is configured to maintain an output DC voltage substantially within a capture range despite vibration on the inertial sensor.