METHOD OF DETERMINING WHEN TOOL STRING PARAMETERS SHOULD BE ALTERED TO AVOID UNDESIRABLE EFFECTS THAT WOULD LIKELY OCCUR IF THE TOOL STRING WERE EMPLOYED TO DRILL A BOREHOLE AND METHOD OF DESIGNING A TOOL STRING

• US 20160076368A1
• Filed: 09/11/2014
• Published: 03/17/2016
• Est. Priority Date: 09/11/2014
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Forstner, Ingo, Linke, Christian
• Granted Patent: US 10,053,913 B2
• Time in Patent Office: Days
• 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 7/00 Special methods or apparatus for drilling

Abstract

A method of determining when tool string parameters should be altered to avoid undesirable effects that would likely occur if the tool string were employed to drill a borehole includes, modeling portions or an entirety of the tool string in the borehole under steady state loading conditions, identifying deflections of the tool string with the modeling when buckling would occur for specific tool string parameters, and calculating whether whirl exhibiting similar deflections of the tool string to those identified during buckling would be undesirable.

Claims

1. A method of determining when tool string parameters should be altered to avoid undesirable effects that would likely occur if the tool string were employed to drill a borehole, comprising:

modeling portions or an entirety of the tool string in the borehole under steady state loading conditions;

identifying deflections of the tool string with the modeling when buckling would occur for specific tool string parameters; and

calculating whether whirl exhibiting similar deflections of the tool string to those identified during buckling would be undesirable.

2. The method of claim 1, further comprising varying the specific tool string parameters during the modeling.

3. The method of claim 1, further comprising determining a contribution that a dimension between adjacent stabilizers has to buckling of the tool string.

4. The method of claim 1, further comprising determining a contribution that radial clearance between the tool string and walls of the borehole has to buckling of the tool string.

5. The method of claim 1, further comprising calculating where the tool string will make contact with walls of the borehole.

6. The method of claim 1, further comprising calculating individual and/or cumulative normal forces between the tool string and walls of the borehole.

7. The method of claim 1, further comprising calculating fatigue of the tool string.

8. The method of claim 1, further comprising calculating frictional wear of the tool string against walls of the borehole.

9. The method of claim 1, further comprising calculating impact forces between the tool string and walls of the borehole using assumptions, estimates, measurements, and analytically derived values of lateral acceleration.

10. The method of claim 1, further comprising calculating inaccuracies of at least one sensor disposed in the tool string due to variations in a relationship between the at least one sensor and walls of the borehole.

11. The method of claim 1, further comprising calculating damage to at least one sensor disposed in the tool string.

12. The method of claim 1, further comprising assuming the whirl is backwards whirl.

13. The method of claim 1, wherein portions of the tool string modeled include a bottom hole assembly positioned within a borehole in an earth formation.

14. A method of designing a tool string comprising:

modeling the tool string;

applying simulated loads at steady state on the tool string as modeled that create buckling;

determining whether whirl of the tool string with a similar deflection and contact force distribution as simulated buckling will be undesirable; and

setting design parameters that allow buckling of the modeled tool string as long as whirling at similar deflection and contact force distribution as simulated buckling is not undesirable.

15. The method of claim 14, further comprising modeling the tool string with finite element analysis.

16. The method of claim 14, wherein the setting design parameters includes setting dimensions of stabilizers on the tool string.

17. The method of claim 14, wherein the setting design parameters includes setting dimensions between adjacent stabilizers along the tool string.

18. The method of claim 14, wherein the setting design parameters includes setting a dimensions between a sensor and a stabilizer.

19. The method of claim 14, wherein the setting design parameters includes setting stiffness of a portion of the tool string.

20. The method of claim 14, wherein the setting design parameters includes setting clearance between the tool string and walls of a borehole.