Method and apparatus for determining drill string movement mode

• US 20050071120A1
• Filed: 10/01/2004
• Published: 03/31/2005
• Est. Priority Date: 04/19/2002
• Status: Active Grant

• Current Assignee: Mark W. Hutchinson
• Original Assignee: Mark W. Hutchinson
• Inventors: Hutchinson, Mark W.
• Granted Patent: US 7,114,578 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• 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 47/04 Measuring depth or liquid level

Abstract

A method is disclosed for determining movement mode in a drill string. The method includes measuring lateral acceleration of the drill string, determining lateral position of the drill string from the acceleration measurements, and determining mode from the position with respect to time. Also disclosed is a method including measuring drill string acceleration along at least one direction, spectrally analyzing the acceleration, and determining existence of a particular mode from the spectral analysis. Also disclosed is a method for determining destructive torque on a BHA including measuring angular acceleration at at least one location along the BHA, and comparing the acceleration to a selected threshold. The threshold relates to a moment of inertia of components of the BHA and a maximum torque applicable to threaded connections between BHA components. A warning is generated when acceleration exceeds the threshold.

Claims

1. A method for determining a mode of movement in a drill string, comprising:

measuring lateral acceleration of the drill string;

determining a lateral position of the drill string with respect to time from the acceleration measurements; and

determining the mode from the position with respect to time.

2. The method as defined in claim 1 wherein the lateral acceleration is measured in two directions orthogonal to each other and to an axis of the drill string.

3. The method as defined in claim 1 wherein the measuring acceleration is performed in a bottom hole assembly.

4. The method as defined in claim 1 further comprising transmitting an indication of the identified mode to the earth'"'"'s surface.

5. The method as defined in claim 4 wherein the transmitting comprises formatting a mud pressure modulation telemetry scheme.

6. The method as defined in claim 1 further comprising adjusting at least one drilling operating parameter in response to the identified mode to reduce effects of the identified mode on the drill string.

7. The method as defined in claim 6 wherein the at least one drilling operating parameter comprises at least one of weight on bit, rotary speed of the drill string and flow rate of a drilling fluid.

8. The method as defined in claim 1 wherein the determining the lateral position comprises doubly integrating the measurements of lateral acceleration.

9. The method as defined in claim 1 further comprising actuating an automatic downhole control system in response to the identified mode to reduce the effects of the identified mode on the drill string.

10. A method for determining a mode of motion of a drill string, comprising:

measuring a parameter related to acceleration of the drill string along at least one direction;

spectrally analyzing the measurements of acceleration; and

determining existence of a particular mode from the spectrally analyzed measurements, wherein the determining the particular mode comprises identifying a component frequency in the spectrally analyzed measurements which corresponds to at least one of a resonant frequency and a whirl frequency of a selected component of the drill string.

11. The method as defined in claim 10 wherein the at least one frequency corresponds to at least one of whirling rate, torsional resonance, axial resonance and lateral resonance of the selected component of the drill string.

12. The method as defined in claim 11 further comprising determining when an amplitude of the component frequency exceeds a selected threshold, and transmitting an indication of a destructive condition to the earth'"'"'s surface.

13. The method as defined in claim 12 wherein the transmitting comprises formatting a mud pressure modulation telemetry scheme.

14. The method as defined in claim 12 further comprising adjusting at least one drilling operating parameter in response to receipt of the indication so as to reduce the amplitude of the resonant frequency.

15. The method as defined in claim 14 wherein the at least one drilling parameter comprises at least one of weight on bit, rotational speed of the drill string and a rate of flow of a drilling fluid

16. The method as defined in claim 10 further comprising communicating existence of the mode to an automatic downhole control system to reduce effects of the mode on components of the drill string.

17. The method as defined in claim 10 wherein the resonant frequency is determined by modeling components of the drill string.

18. The method as defined in claim 10 wherein the particular mode comprises at least one of lateral shock and whirl

19. A method for determining destructive torque on a bottom hole assembly, comprising:

measuring a parameter related to angular acceleration at at least one location along the drill string;

comparing angular acceleration determined from the measured parameter to a selected threshold, the selected threshold related to a moment of inertia of selected components of the drill string and a maximum torque applicable to at least one of threaded connections between the selected components, and tubular components of a drill string; and

generating a warning indication when the angular acceleration exceeds the selected threshold.

20. The method as defined in claim 19 wherein the generating a warning indication comprises reformatting a mud pressure modulation telemetry scheme.

21. The method as defined in claim 19 wherein the selected components comprise at least one of a bit, a mud motor, an MWD tool, a joint of drill pipe, a stabilizer and a drill collar.

22. The method as defined in claim 19 further comprising changing at least one drilling operating parameter in response to the generating the warning indication.

23. The method as defined in claim 22 wherein the at least one drilling operating parameter comprises at least one of weight on bit, rotary speed of the drill string and flow rate of a drilling fluid

24. The method as defined in claim 19 wherein the parameter comprises angular acceleration

25. The method as defined in claim 19 wherein the parameter comprises torque measured in at least one component of the bottom hole assembly.

26. The method as defined in claim 25 further comprising determining a periodicity of the torque, measuring a rotational speed variation of the bottom hole assembly, and determining angular acceleration from a waveform having amplitude corresponding to the variation of rotational speed and periodicity corresponding to the periodicity of the torque.

27. The method as defined in claim 19 wherein the parameter comprises rotational speed of the bottom hole assembly.

28. The method as defined in claim 27 further comprising determining angular acceleration from the rotational speed of the bottom hole assembly.

29. The method as defined in claim 28 wherein the determining angular acceleration comprises fitting a periodic waveform to the rotational speed of the bottom hole assembly, and determining the angular acceleration from the periodic waveform.

30. The method as defined in claim 19 wherein the parameter comprises torque applied to a drill string at the earth'"'"'s surface.

31. The method as defined in claim 19 further comprising:

measuring a parameter related to axial acceleration of the bottom hole assembly;

determining axial forces from the measured parameter;

combining the determined axial forces with a torque determined from the parameter related to angular acceleration; and

generating a warning signal when the combined torque and axial force exceeds a combined safe operating threshold.

32. A method for estimating wear on a drill string, comprising:

determining a mode of motion of the drill string;

calculating side forces generated by contact between affected components of the drill string and a wall of a wellbore as a result of the mode of motion; and

estimating a wear rate corresponding to the side forces and a rate of rotation of the drill string.

33. The method as defined in claim 32, wherein the determining the mode of motion comprises measuring a parameter related to acceleration at at least one location along the drill string, determining a lateral position of the drill string with respect to time from the acceleration measurements, and determining the mode from the position with respect to time.

34. A method for estimating fatigue on a drill string, comprising:

determining a mode of motion of the drill string;

calculating flexural forces generated as a result of the mode of motion; and

estimating a fatigue rate from the flexural forces.

35. The method as defined in claim 34, wherein the determining the mode of motion comprises measuring a parameter related to acceleration at at least one location along the drill string, determining a lateral position of the drill string with respect to time from the acceleration measurements, and determining the mode from the position with respect to time.

36. An apparatus for determining mode of movement in a drill string, comprising:

a sensor for measuring lateral acceleration of the drill string;

means for determining a lateral position of the drill string with respect to time from the acceleration measurements; and

means for determining the mode from the position with respect to time.

37. The apparatus as defined in claim 36 wherein the sensor for measuring acceleration includes components disposed in two directions orthogonal to each other and to an axis of the drill string.

38. The apparatus as defined in claim 36 wherein the sensor for measuring acceleration is disposed in a bottom hole assembly.

39. The apparatus as defined in claim 36 further comprising means for transmitting an indication of the identified mode to the earth'"'"'s surface.

40. The apparatus as defined in claim 39 wherein the means for transmitting comprises means for formatting a mud pressure modulation telemetry scheme.

41. The apparatus as defined in claim 39 wherein the means for determining the lateral position comprises means for doubly integrating an output of the sensor for measuring lateral acceleration.

42. A apparatus for determining a mode of motion of a drill string, comprising:

a sensor for measuring a parameter related to acceleration of the drill string along at least one direction;

a spectral analyzer operatively coupled to the sensor; and

means for determining existence of a particular mode from the spectrally analyzed measurements the means for determining the particular mode comprising means for identifying a component frequency operatively coupled to the spectral analyzer, the component frequency corresponds to at least one of whirl rate, torsional resonance, axial resonance and lateral resonance of the selected component of the drill string.

43. The apparatus as defined in claim 42 further comprising means for determining when an amplitude of the component frequency exceeds a selected threshold, and means for transmitting an indication of a destructive condition to the earth'"'"'s surface.

44. The apparatus as defined in claim 43 wherein the means for transmitting comprises means for formatting a mud pressure modulation telemetry scheme.

45. The apparatus as defined in claim 42 wherein the component frequency is determined by modeling components of the drill string.

46. An apparatus for determining destructive torque on a bottom hole assembly, comprising:

a sensor measuring angular acceleration at at least one location along the drill string;

means for comparing angular acceleration to a selected threshold operatively coupled to the sensor, the selected threshold related to a moment of inertia of selected components of the bottom hole assembly and a maximum torque applicable to threaded connections between the selected components; and

means for generating a warning indication when the angular acceleration exceeds the selected threshold.

47. The apparatus as defined in claim 46 wherein the means for generating a warning indication comprises means for reformatting a mud pressure modulation telemetry scheme.

48. The apparatus as defined in claim 46 wherein the selected components comprise at least one of a bit, a joint of drill pipe, a mud motor, an MWD tool, a stabilizer and a drill collar.

49. A method for determining an excessive torque condition in a wellbore, comprising:

measuring a parameter related to torque on components of a drill string in the wellbore;

determining a torque exerted by a drill bit coupled to a lower end of the bottom hole assembly;

determining a torque needed to rotate a drill string coupled above the bottom hole assembly;

determining a difference between a sum of the drill bit torque and the required drill string torque, and a torque determined from the measured parameter required to rotate the drill string from the earth'"'"'s surface; and

indicating the excessive torque condition when the difference exceeds a selected threshold.