Downhole dynamics measurements using rotating navigation sensors

• US 9,483,607 B2
• Filed: 11/10/2011
• Issued: 11/01/2016
• Est. Priority Date: 11/10/2011
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Sugiura, Junichi
• Primary Examiner(s): Lee, Paul D
• Application Number:
  US13/293,944
• Publication Number:
  US 20130124095A1
• Time in Patent Office: 1,818 Days
• Field of Search: 702/9
• US Class Current: 1/1
• CPC Class Codes: E21B 44/00 Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
• CPC Class Codes: E21B 47/007 Measuring stresses in a pipe string or casing for locating blocked portions of pipes E21B47/09
• CPC Class Codes: E21B 7/04 Directional drilling
• CPC Class Codes: G01H 11/00 Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A method for making downhole dynamics measurements using rotating navigational sensors includes rotating navigational accelerometers in a subterranean borehole to obtain a string of accelerometer measurements while rotating. The measurements are differentiated to obtain a string of differentiated accelerometer measurements and may then be further processed to obtain a drill string vibration parameter. Substantially simultaneous magnetometer measurements may be obtained and utilized to compute a corrected vibration parameter in which at least one of a gravitational acceleration component, a tangential acceleration component, and a centripetal acceleration component is removed from the vibration parameter.

Claims

1. A method for making downhole dynamics measurements in a drill string, the method comprising:

(a) rotating a downhole navigational sensor set in a borehole, the navigational sensor set deployed in the drill string and including at least first, second, and third tri-axial accelerometers;

(b) causing the navigational sensor set to obtain a string of accelerometer measurements, the string of accelerometer measurements including a plurality of tri-axial accelerometer measurements made at a predetermined measurement interval;

(c) differentiating the string of accelerometer measurements obtained in (b) to obtain a corresponding string of differentiated accelerometer measurements;

(d) causing a downhole processor to process the differentiated accelerometer measurements obtained in (c) to obtain a drill string vibration parameter;

(e) causing the downhole processor to further process the drill string vibration parameter obtained in (d) so as to remove at least one of a gravitational acceleration component, a tangential acceleration component, and a centripetal acceleration component to obtain a corrected drill string vibration parameter; and

(f) implementing one or more corrective measures based on the corrected drill string vibration parameter, wherein the corrective measures comprise the step of adjusting a dynamic drilling condition, the dynamic drilling condition comprising axial vibration, lateral shock, lateral vibration, torsional vibration and/or stick/slip.

2. The method of claim 1, wherein the corrected drill string vibration parameter is obtained in (e) by subtracting a gravitational acceleration component from the drill string vibration parameter obtained in (d).

3. The method of claim 2, wherein the gravitational acceleration component is proportional to a borehole inclination and a rotation rate of the navigational sensor set in the borehole.

4. The method of claim 2, wherein the gravitational acceleration component is computed according to one of the following equations:

5. The method of claim 1, wherein the corrected drill string vibration parameter is obtained in (e) by subtracting a tangential acceleration component from the drill string vibration parameter obtained in (d).

6. The method of claim 5, wherein the tangential acceleration component is computed using magnetic field measurements made substantially simultaneously with the accelerometer measurements.

7. The method of claim 5, wherein the tangential acceleration component is computed according to one of the following equations:

Ti_Δ

=maxTi−

minTi

Ti_Δ

=2maxTi

wherein Ti_Δ

represents the tangential acceleration component, Ti represents a substantially instantaneous tangential acceleration, maxTi and minTi represent the maximum and minimum instantaneous tangential accelerations within a set of measurements, and i represents the x- or y-axis.

8. The method of claim 7, wherein the instantaneous tangential acceleration is computed according to the following equation:

9. The method of claim 1, wherein the corrected drill string vibration parameter is obtained in (e) by subtracting a centripetal acceleration component from the drill string vibration parameter obtained in (d).

10. The method of claim 9, wherein the centripetal acceleration component is computed using magnetic field measurements made substantially simultaneously with the accelerometer measurements.

11. The method of claim 9, wherein the centripetal acceleration component is computed according to the following equation:

Ci_Δ

=maxCi−

minCi

wherein Ci_Δ

represents the centripetal acceleration component, Ci represents a substantially instantaneous centripetal acceleration, maxCi and minCi represent the maximum and minimum tangential accelerations within a set of measurements, and i represents the x- or y-axis.

12. The method of claim 11, wherein the instantaneous centripetal acceleration is computed according to the following equation: