Radial force distributions in rock bits
A method for designing a drill bit in an earth formation, including defining parameters for a simulation of the drill bit drilling in earth formation, where the parameters comprise at least bit design parameters; executing the defined simulation; obtaining radial forces resulting from the executing of the defined simulation; applying a criterion to the obtained radial forces; and adjusting one of the at least bit design parameters in response to the applying of the criteria.
1. A method for designing a drill bit, comprising:
determining radial forces acting on a selected drill bit during simulated drilling;
summing magnitudes of the radial forces with respect to a direction to generate a sum of the radial forces;
comparing the sum of the radial forces to an applied weight on bit;
generating a ratio between the sum of the radial forces and the applied weight on bit;
adjusting at least one parameter of the selected drill bit based on the generated ratio until the magnitude of the radial forces remains at a value less than a predetermined value for a duration of a preselected amount of time during simulated drilling; and
outputting a drill bit design based on the generated ratio and the adjusting.
2. The method of claim 1 , wherein the at least one parameter comprises at least one selected from the group consisting of a performance parameter, an environment parameter, and a simulation parameter.
3. The method of claim 2 , wherein the performance parameter comprises drilling parameters.
4. The method of claim 2 , wherein the environment parameter comprises cutting element interaction data and bottom hole geometry data.
5. The method of claim 1 , wherein the determining the radial forces comprises:
rotating the selected drill bit;
calculating a new location of a cutting element on the selected drill bit;
determining an interference between the cutting element and an earth formation at the new location; and
calculating a radial force acting on the earth formations based on the interference at the new location.
6. The method of claim 1 , wherein the selected drill bit is a roller cone drill bit.
7. The method of claim 6 , wherein bit design parameters of the selected drill bit comprise at least one selected from the group consisting of a cone profile, a cone axis offset, a number of cutting elements on each cone, a location of a cutting element of the selected drill bit, a size of a cutting element of the selected drill bit, a shape of a cutting element of the selected drill bit, and an orientation of a cutting element of the selected drill bit.
8. The method of claim 1 , wherein the selected drill bit is a fixed cutter drill bit.
9. The method of claim 8 , wherein bit design parameters of the selected drill bit comprise at least one selected from the group consisting of a cutter location, a cutter orientation, a cutter size, a cutter shape, and a cutter bevel size, a bit profile, a bit diameter, a number of blades on the selected drill bit, a blade geometry, a blade location, a junk slot area, and a bit axial offset.
10. The method of claim 1 , wherein the ratio of the sum of the radial forces to the applied weight on bit is less than or equal to 0.20.
11. The method of claim 1 , wherein the ratio of the sum of the radial forces to the applied weight on bit is less than or equal to 0.10.
12. The method of claim 1 , wherein the ratio of the sum of the radial forces to the applied weight on bit is less than or equal to 0.05.
13. The method of claim 1 , wherein the simulated drilling comprises dynamic simulation.
14. The method of claim 1 , wherein the evaluating the radial forces comprises:
plotting magnitudes of the radial forces with respect to at least one selected from the group consisting of a direction of force, a frequency of occurrence, and time, to generate a radial force plot.
15. The method of claim 14 , wherein the radial force plot comprises a polar plot of the magnitudes and directions of the resultant radial forces.
16. The method of claim 15 , wherein the polar plot indicates that the resultant radial forces are less than a predetermined value for a selected percentage of the time during the simulated drilling.
17. The method of claim 16 , wherein the selected percentage of the time during the simulated drilling is 70%.
18. The method of claim 14 , wherein the radial force plot comprises a chart plot of the resultant radial force.
19. The method of claim 18 , wherein the chart plot indicates that the radial resultant forces are less than a predetermined value for a selected percentage of the time during the simulated drilling.
20. The method of claim 19 , wherein the selected percentage of the time during the simulated drilling is 70%.
21. The method of claim 14 , wherein the radial force plot comprises a box-whisker plot of the resultant radial forces.
22. The method of claim 21 , wherein the box-whisker plot indicates that the resultant radial forces are less than a predetermined value for a selected percentage of the time during simulated drilling.
23. The method of claim 22 , wherein the selected percentage of the time during the simulated drilling is 70%.
24. A method for designing a bottomhole assembly, comprising:
determining radial forces acting on a bottom hole assembly during simulated drilling, said bottom hole assembly including a drill bit;
summing magnitudes of the radial forces with respect to a direction to generate a sum of the radial forces;
comparing the sum of the radial forces to an applied weight on bit;
generating a ratio between the sum of the radial forces and the applied weight on bit;
adjusting at least one parameter of the bottom hole assembly based on the generated ratio until the generated ratio remains at a value less than a predetermined value for a duration of a preselected amount of time during simulated drilling; and
outputting a bottom hole assembly design based on the generated ratio and the adjusting.
25. The method of claim 24 , wherein the graphically displaying occurs in real time.
26. The method of claim 24 , wherein the evaluating the radial forces comprises:
plotting a magnitude of the radial forces with respect to at least one selected from a group of direction of force, frequency of occurrence, time, to generate a radial force plot.
27. The method of claim 26 , wherein the radial force plot comprises a polar plot of the magnitudes and directions of the resultant radial forces.
28. The method of claim 27 , wherein the polar plot indicates that the resultant radial forces are less than a predetermined value for a selected percentage of the time during the simulated drilling.
29. The method of claim 28 , wherein the selected percentage of the time during the simulated drilling is 70%.
30. The method of claim 26 , wherein the radial force plot comprises a chart plot of the resultant radial force.
31. The method of claim 30 , wherein the chart plot indicates that the radial resultant forces are less than a predetermined value for a selected percentage of the time during the simulated drilling.
32. The method of claim 31 , wherein the selected percentage of the time during the simulated drilling is 70%.
33. The method of claim 26 , wherein the radial force plot comprises a box-whisker plot of the resultant radial forces.
34. The method of claim 33 , wherein the box-whisker plot indicates that the resultant radial forces are less than a predetermined value for a selected percentage of the time during simulated drilling.
35. The method of claim 34 , wherein the selected percentage of the time during the simulated drilling is 70%.
36. The method of claim 24 , further comprising adjusting bit design parameters.
37. The method of claim 36 , wherein the bottomhole assembly comprises a roller cone drill bit; and wherein the bit design parameters comprise at least one of a group consisting of a cone profile, a cone axis offset, a number of cutting elements on each cone, a location of a cutting element of the drill bit, a size of a cutting element of the drill bit, a shape of a cutting element of the drill bit, and an orientation of a cutting element of the drill bit.
38. The method of claim 36 , wherein the bottomhole assembly comprises a fixed cutter drill bit; and wherein the bit design parameters comprise at least one of a group consisting of a cutter location, a cutter orientation, a cutter size, a cutter shape, and a cutter bevel size, a bit profile, a bit diameter, a number of blades on the bit, a blade geometry, a blade location, a junk slot area, and a bit axial offset.
39. The method of claim 24 , wherein the simulated drilling comprises dynamic simulation.