Tensile and compressive stresses

• US 20050159937A1
• Filed: 12/10/2004
• Published: 07/21/2005
• Est. Priority Date: 03/13/2000
• Status: Active Grant

• Current Assignee: Smith International Incorporated (Schlumberger NV)
• Original Assignee: Smith International Incorporated (Schlumberger NV)
• Inventors: Huang, Sujian J.
• Granted Patent: US 7,356,450 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 bit that includes steps of selecting design parameters for the roller cone bit, drilling parameters, and parameters of an earth formation, simulating drilling of the earth formation by the roller cone bit using the selected drilling parameters, calculating drilling performance parameters from the simulated drilling, and analyzing at least one of a tensile stress or a compressive stress parameters for a cutting element of the roller cone bit from the calculated drilling performance parameters is disclosed.

Claims

1. A method for designing a roller cone bit, comprising:

(a) selecting design parameters for the roller cone bit, drilling parameters, and parameters of an earth formation;

(b) simulating drilling of the earth formation by the roller cone bit using the selected drilling parameters;

(c) calculating drilling performance parameters from the simulated drilling; and

(d) analyzing at least one of a tensile stress or a compressive stress parameters for a cutting element of the roller cone bit from the calculated drilling performance parameters.

2. The method of claim 1, further comprising

(e) adjusting at least one of the design parameters for the roller cone bit, drilling parameter, and the parameters of the earth formation;

and

(f) repeating steps (b)-(d) to change a simulated performance of the roller cone bit.

3. The method of claim 1, wherein the tensile stress parameter comprises at least one of a maximum tensile stress, a median tensile stress, and an average tensile stress.

4. The method of claim 1, wherein the compressive stress parameter comprises at least one of a maximum compressive stress, a median compressive stress, and an average compressive stress.

5. The method of claim 1, wherein the tensile stress parameter is calculated for the cutting element of the roller cone bit from the calculated drilling performance parameters

6. The method of claim 1, wherein the tensile stress parameter is calculated for a row of cutting elements of the roller cone bit from the calculated drilling performance parameters.

7. The method of claim 1, wherein the tensile stress parameter is calculated for a roller cone of the roller cone bit from the calculated drilling performance parameters.

8. The method of claim 1, wherein the compressive stress parameter is calculated for the cutting element of the roller cone bit from the calculated drilling performance parameters.

9. The method of claim 1, wherein the compressive stress parameter is calculated for a row of cutting elements of the roller cone bit from the calculated drilling performance parameters.

10. The method of claim 1, wherein the compressive stress parameter is calculated for a roller cone of the roller cone bit from the calculated drilling performance parameters.

11. The method of claim 1, wherein both the tensile stress parameter and the compressive stress parameter are analyzed.

13. A roller bit designed by the method of claim 1.

12. The method of claim 12, wherein the tensile stress parameter for the cutting element is related to the compressive stress parameter for the cutting element.

14. A method for optimizing drilling performance of a roller cone bit design, comprising:

selecting a roller cone bit design, drilling parameters, and parameters of an earth formation desired to be drilled;

calculating at least one of the tensile stress value and compressive stress value induced on the roller cone bit based on the drilling parameters and the parameters of the earth formation;

adjusting at least one of the roller cone bit design, the drilling parameters, and the parameters of the earth formation according to at least one of the tensile stress value and the compressive stress value; and

repeating the calculating and adjusting until an optimized drilling performance is achieved.

15. The method of claim 15, wherein both the tensile stress value and compressive stress value are calculated.

16. A method for generating a visual representation of a roller cone bit drilling in an earth formation, comprising:

simulating the roller cone bit drilling in the earth formation;

calculating at least one of a tensile stress parameter and compressive stress parameter; and

displaying at least one of the tensile stress parameter and compressive stress parameter in said visual representation.