Bending moment

• US 20050165589A1
• Filed: 12/10/2004
• Published: 07/28/2005
• Est. Priority Date: 03/13/2000
• Status: Active Grant

• Current Assignee: Smith International Incorporated (SLB)
• Original Assignee: Smith International Incorporated (SLB)
• Inventors: Huang, Sujian J.
• Granted Patent: US 7,260,514 B2
• Time in Patent Office: Days
• US Class Current: 703/6
• CPC Class Codes: E21B 10/16 characterised by tooth form or arrangement

Abstract

A method for designing a roller cone drill bit comprising selecting bit design parameters, selecting parameters of an earth formation, selecting drilling parameters, simulating drilling a selected earth formation, determining force on at one of a cutting element, a cone, and a drill bit, determining a location of the force, calculating bending moment, and varying at least one of the bit design parameters and repeating the simulating and the calculating until the bending moment meets a selected criterion. The method further comprising converting said bending moment into a visual representation.

Claims

1. A method for designing a drill bit, the method comprising:

selecting bit design parameters;

selecting parameters of an earth formation;

selecting drilling parameters;

simulating drilling the earth formation;

calculating a bending moment acting on the drill bit; and

varying at least one of the bit design parameters and repeating the simulating and the calculating until the bending moment meets a selected criterion.

2. The method of claim 1, wherein the bit design parameters comprise at least one of cutting element count, cutting element height, cutting element geometrical shape, cutting element spacing, cutting element orientation, cone axis offset, cutting element material, cutting element location, cone diameter profile, and bit diameter.

3. The method of claim 1, further comprising determining force acting on at least one of a cutting element, a cone, and a drill bit.

4. The method of claim 3, further comprising determining location of the force.

5. The method of claim 1, further comprising determining of bending moments amplitudes.

6. The method of claim 5, further comprising limiting the amplitudes of the bending moments.

7. The method of claim 4, further comprising determining the frequency of bending moments.

8. The method of claim 7, further comprising limiting the frequency of bending moments.

9. The method of claim 5, further comprising determining the frequency of a selected bending moment amplitude.

10. The method of claim 9, further comprising limiting the frequency of a selected bending moment amplitude.

11. The method of claim 1, wherein the parameters of the earth formation comprise a hardness of the formation.

12. The method of claim 1, wherein said bit design parameters form part of a computer aided design file.

13. The method of claim 1, wherein said drilling parameters comprise weight on bit.

14. The method of claim 1, wherein said drilling parameters comprise rotational speed of a bit.

15. The method of claim 1, wherein the simulating incrementally rotating said drill bit is repeated until an optimized roller cone drill bit design is achieved.

16. The method of claim 1, further comprising converting said bending moment into a visual representation.

17. The method of claim 16, wherein the visual representation is in tabular form.

18. The method of claim 16, wherein the visual representation is a graphical display of the drill bit showing said calculated bending moments.

19. A drill bit designed by the method of claim 1.