Methods for modeling, displaying, designing, and optimizing fixed cutter bits

• US 20050133272A1
• Filed: 07/09/2004
• Published: 06/23/2005
• Est. Priority Date: 03/13/2000
• Status: Active Grant

• Current Assignee: Smith International Incorporated (Schlumberger NV)
• Original Assignee: Smith International Incorporated (Schlumberger NV)
• Inventors: Cariveau, Peter T., Huang, Sujian
• Granted Patent: US 7,693,695 B2
• Time in Patent Office: Days
• US Class Current: 175/327
• CPC Class Codes: E21B 10/00 Drill bits specially adapted for deflecting the direction of boring E21B7/064; with means for collecting substances E21B27/00

Abstract

In one aspect, the invention provides a method for modeling the performance of a fixed cutter bit drilling an earth formation. In one embodiment, the method includes selecting a drill bit and an earth formation to be represented as drilled, simulating the bit drilling the earth formation, displaying the simulating, and adjusting at least one parameter affecting the performance. The method of design is used to make a fixed cutter drill bit. In another embodiment the method includes numerically rotating the bit, calculating bit interaction with the earth formation during the rotating, and determining the forces on the cutters during the rotation based on the calculated interaction with earth formation and empirical data.

Claims

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

simulating the fixed cutter drill bit drilling in an earth formation;

graphically displaying of at least a portion of the simulating;

adjusting a value of at least one design parameter for the fixed cutter drill bit according to the graphical display; and

repeating the simulating, displaying and adjusting to change a simulated performance of the fixed cutter drill bit.

2. The method of claim 1, further comprising repeating the simulating and adjusting to optimize a performance characteristic.

3. The method of claim 1, further comprising graphically displaying at least one fixed cutter drill bit design parameter.

4. The method of claim 1, wherein simulating further comprises:

simulating one or more performance characteristics at a plurality of increments of simulated fixed cutter drill bit rotation.

5. The method of claim 1, wherein simulating further comprises:

selecting one or more parameters affecting drilling performance from the group consisting of control model type parameters, drill string design parameters, drill bit design parameters, earth formation parameters, drill bit/formation interface configuration parameters, and drilling operating parameters.

6. The method of claim 5, wherein the control model type parameters comprise at least one of cutter/formation control model, weight on bit (WOB) control model, and rate of penetration control (ROP) control model, constrained centerline model, and dynamic model.

7. The method of claim 5, wherein the drill string design parameters comprise at least one of number of components, type of components, material of components, length, strength and elasticity of components, O.D. of components, I.D. of components, nodal division of components, type of down hole assembly, length, strength, elasticity, density, density in mud, O.D. and I.D. of down hole assembly, hook load, drill bit type, drill bit design parameters, length, diameter, strength, elasticity, O.D., I.D. and wear model of drill bit, number of blades, orientation of blades, shape, size strength, elasticity, OD, ID and wear model of blades.

8. The method of claim 5, wherein the drill bit design parameters comprise at least one of number of cutters, bit cutting profile, position of cutters on drill bit blades, bit axis offset of the cutter, bit diameter, cutter radius on bit, cutter vertical height on bit, cutter inclination angle on bit, cutter body shape, cutter size, cutter height, cutter diameter, cutter orientation, cutter back rake angle, cutter side rake angle, working surface shape, working surface orientation, bevel size, bevel shape, bevel orientation, cutter hardness, PDC table thickness, and cutter wear model.

9. The method of claim 5, wherein the earth formation parameters comprise at least one of formation layer type, formation mechanical strength, formation density, formation wear characteristics, formation non-homogeneity, formation strength, anisotropic orientation, borehole diameter, empirical test data for earth formation type, multiple layer formation interfaces, formation layer depth, formation layer interface dip angle, formation layer interface strike angle, and empirical test data for multiple layer interface.

10. The method of claim 5, wherein the drilling operation parameters comprise at least one of the group consisting of weight on bit, bit torque, rate of penetration, rotary speed, rotating time, wear flat area, hole diameter, mud type, mud density, vertical drilling, drilling tilt angle, platform/table rotation, directional drilling, down hole motor rotation, bent drill string rotation, and side load.

11. The method of claim 5, wherein the graphically displaying comprises graphically displaying at least one of the group consisting of bottom hole pattern, forces on bit, torque, weight on bit, imbalanced force components, total imbalanced force on bit, vector angle of total imbalanced force on bit, imbalance of forces on blade, forces on blades, radial force, circumferential force, axial force, total force on blade, vector angle of total force, imbalance of forces on blade, forces on cutters, cutter forces defined in a selected Cartesian coordinate system, radial cutter force, circumferential cutter force, axial cutter force, an angle (Beta) between the radial force component and the circumferential force component of total imbalance force, total force on cutter, vector angle of total force, imbalance of forces on cutter, back rake angle of cutter against the formation, side rake angle, cut shape on cutters, wear on cutters, and contact of bit body with formation, impact force, restitution force, location of contact on bit or drill string, and orientation of impact force.

12. The method of claim 1, wherein simulating comprises determining one or more from the group consisting of bottom hole pattern, forces on bit, torque, weight on bit, imbalanced force components in a selected Cartesian coordinate system, total imbalanced force on bit, vector angle of total imbalanced force on bit, imbalance of forces on blade, forces on blades, forces defined in a selected Cartesian coordinate system, total force on blade, vector angle of total force on blade, imbalance of forces on blade, forces on cutters, forces on the cutter defined in a selected Cartesian coordinate system, normal cutter force (Fn), cutting force (Fc), side force (Fs), total force on cutter (Ft), vector angle of total force, imbalance of forces on cutter, back rake angle of cutter against the formation, side rake angle, cut shape on cutters, wear on cutters, and contact of bit body with formation, impact force, restitution force, location of contact on bit or drill string, and orientation of impact force.

13. The method of claim 1, wherein simulating further comprises simulating a plurality of increments of rotation of the fixed cutter drill bit drilling in the earth formation.

14. The method of claim 13, wherein graphically displaying at least a portion of the simulating further comprises:

graphically displaying a portion of the simulating at a selected one of the plurality of increments of rotation of the fixed cutter drill bit drilling in the earth formation.

15. The method of claim 13, wherein graphically displaying at least a portion of the simulating further comprises:

graphically displaying a portion of the simulating corresponding to the plurality of increments of rotation of the fixed cutter drill bit drilling in the earth formation.

16. The method of claim 1, wherein the graphically displaying comprises:

displaying, on a single display screen, a combination of numeric values representing input parameters affecting simulated performance of the fixed cutter drill bit and simulated performance characteristics.

17. The method of claim 1, wherein the graphically displaying comprises:

displaying a three-dimensional graphical depiction of a bottomhole pattern cut into the earth formation by the dill bit.

18. The method of claim 1, wherein the graphically displaying comprises:

displaying a three-dimensional graphical depiction of at least one cutter of the dill bit of the simulation spatially oriented relative to the drill bit, the three-dimensional graphical depiction including a cutter/formation interface contact area shape.

19. The method of claim 1, wherein the graphically displaying comprises:

displaying a three-dimensional graphical depiction of at least one cutter of the fixed cutter dill bit of the simulation, spatially oriented relative to at least one other cutter of the fixed cutter drill bit of the simulation, the three-dimensional graphical depiction including a cutter/formation interface contact area shape.

20. The method of claim 19, wherein the three-dimensional graphical depiction including a cutter/formation interface contact area shape further comprises a color coded indication of force distribution on the contact area.

21. The method of claim 20, further comprising a graphical depiction of a force vector acting on the at least one spatially oriented cutter.

22. The method of claim 1, wherein the graphically displaying comprises:

displaying a three-dimensional graphical depiction of at least one cutter of the fixed cutter dill bit of the simulation spatially oriented relative to the fixed cutter dill bit, the three-dimensional graphical depiction including a graphical depiction of cut force and normal force vectors acting on the at least one spatially oriented cutter.

23. The method of claim 1, wherein the graphically displaying comprises:

displaying a three-dimensional depiction of a cut force vector and a normal force vector acting on spatially oriented cutters.

24. The method of claim 1, wherein the graphically displaying comprises:

displaying a total imbalance force vector on the drill bit spatially oriented relative to the drill bit.

25. The method of claim 1, wherein the graphically displaying comprises:

displaying a total imbalance force vector on the drill bit spatially oriented relative to at least one cutter of the drill bit.

26. The method of claim 1, wherein the graphically displaying comprises:

displaying a radial imbalance force component, a circumferential force imbalance component, and a beta angle between the radial imbalance force component and the circumferential force imbalance component.

27. The method of claim 1, wherein the graphically displaying comprises:

displaying a graphical plot of the angle, beta, between the radial component of the total imbalance force vector on the fixed cutter drill bit and the circumferential component of the total imbalance force vector on the fixed cutter drill bit.

28. The method of claim 1, wherein the graphically displaying comprises:

displaying a three-dimensional graphical depiction of the fixed cutter drill bit of the simulation and a graphical depiction of a total imbalance force vector on the drill bit, the graphical depiction of the total imbalance force vector including a circumferential component, a radial component, and a beta angle between the radial and circumferential components spatially oriented relative to at least one cutter of the fixed cutter drill bit and depicted dynamically over a selected interval of time, corresponding to a sequence of a number of incremental portions of rotation.

29. The method of claim 1, wherein the graphically displaying comprises:

displaying a number of cutters in contact with the earth formation at a given point in time during simulated drilling.

30. The method of claim 1, wherein the graphically displaying comprises:

displaying a number of cutters in contact with the earth formation at a plurality of incremental rotation intervals over a selected period of time during simulated drilling.

31. The method of claim 1, wherein the simulating comprises:

solving for a dynamic response of the drill bit to an incremental rotation using a mechanics analysis model, and repeating said solving for a select number of successive incremental rotations.

32. The method of claim 1, wherein the simulating comprises:

solving for a dynamic response of the fixed cutter drill bit to an increment of simulated rotation using a mechanics analysis model, and

repeating the solving, for a plurality of successive increments of simulated rotations.

33. The method of claim 1, wherein the simulating comprises:

determining an offset distance between a centerline of the fixed cutter drill bit and a theoretical centerline of a borehole drilled through an earth formation in response to an increment of simulated rotation of the fixed cutter drill bit using a mechanics analysis model, and

repeating the determining to determine a plurality of offset distances for successive increments of simulated rotation.

34. The method of claim 33, wherein the graphically displaying comprises displaying the determined offset distance between the centerline of the fixed cutter drill bit and the theoretical centerline of the borehole at an increment of simulated rotation of the fixed cutter drill bit.

35. The method of claim 33, wherein the graphically displaying comprises displaying a plurality of determined offset distances between the centerline of the fixed cutter drill bit and the theoretical centerline of the borehole at the plurality of successive increments of simulated rotation.

36. The method of claim 1, wherein the graphically displaying comprises displaying a historical plot of a plurality of determined offset distances between a centerline of the fixed cutter drill bit and a theoretical centerline of the borehole for a plurality of increments of simulated rotation.

37. The method of claim 1, wherein the graphically displaying comprises displaying a dynamic sequence of a plurality of determined offset distances between a centerline of the fixed cutter drill bit and a theoretical centerline of a borehole for a plurality of increments of simulated rotation over a period of time.

158. A fixed cutter drill bit designed by the method of claim 1.

38. A method for designing a fixed cutter drill bit, comprising:

determining a performance characteristic of the fixed cutter drill bit;

graphically displaying the performance characteristic to a design engineer, as the design engineer adjusts at least one design parameter for a fixed cutter bit.

39. The method of claim 38, further comprising graphically displaying at least one fixed cutter drill bit design parameter.

40. The method of claim 38, wherein determining the performance characteristic of the drill bit further comprises:

calculating the performance characteristic at a plurality of increments of rotation.

41. The method of claim 38, wherein determining the performance characteristic of the fixed cutter drill bit comprises:

selecting one or more parameters affecting drilling performance from the group consisting of control model type parameters, drill string design parameters, drill bit design parameters, earth formation parameters, drill bit/formation interface configuration parameters, and drilling operating parameters.

42. The method of claim 41, wherein the control model type parameters comprise at least one of cutter/formation control model, weight on bit (WOB) control model, and rate of penetration control (ROP) control model, constrained centerline model, and dynamic model.

43. The method of claim 41, wherein the drill string design parameters comprise at least one of number of components, type of components, material of components, length, strength and elasticity of components, O.D. of components, I.D. of components, nodal division of components, type of down hole assembly, length, strength, elasticity, density, density in mud, O.D. and I.D. of down hole assembly, hook load, drill bit type, drill bit design parameters, length, diameter, strength, elasticity, O.D., I.D. and wear model of drill bit, number of blades, orientation of blades, shape, size strength, elasticity, OD, ID and wear model of blades.

44. The method of claim 41, wherein the drill bit design parameters comprise at least one of number of cutters, bit cutting profile, position of cutters on drill bit blades, bit axis offset of the cutter, bit diameter, cutter radius on bit, cutter vertical height on bit, cutter inclination angle on bit, cutter body shape, cutter size, cutter height, cutter diameter, cutter orientation, cutter back rake angle, cutter side rake angle, working surface shape, working surface orientation, bevel size, bevel shape, bevel orientation, cutter hardness, PDC table thickness, and cutter wear model.

45. The method of claim 41, wherein the earth formation parameters comprise at least one of formation layer type, formation mechanical strength, formation density, formation wear characteristics, formation non-homogeneity, formation strength, anisotropic orientation, borehole diameter, empirical test data for earth formation type, multiple layer formation interfaces, formation layer depth, formation layer interface dip angle, formation layer interface strike angle, and empirical test data for multiple layer interface.

46. The method of claim 41, wherein the drilling operation parameters comprise at least one of the group consisting of weight on bit, bit torque, rate of penetration, rotary speed, rotating time, wear flat area, hole diameter, mud type, mud density, vertical drilling, drilling tilt angle, platform/table rotation, directional drilling, down hole motor rotation, bent drill string rotation, and side load.

47. The method of claim 41, wherein determining the performance characteristic of the fixed cutter drill bit comprises determining at least one of bottom hole pattern, forces on bit, torque, weight on bit, imbalanced force components in a selected Cartesian coordinate system, total imbalanced force on bit, vector angle of total imbalanced force on bit, an angle (Beta) between the radial force component and the circumferential force component of total imbalance force, imbalance of forces on blade, forces on blades, forces defined in a selected Cartesian coordinate system, radial force (normal force), circumferential force (tangential force), axial force (vertical force), total force on blade, vector angle of total force, imbalance of forces on blade, forces on cutters, cutter forces defined in a selected Cartesian coordinate system, radial cutter force (normal force), circumferential cutter force (tangential force), axial cutter force (vertical force), total force on cutter, vector angle of total force, imbalance of forces on cutter, back rake angle of cutter against the formation, side rake angle, cut shape on cutters, wear on cutters, and contact of bit body with formation, impact force, restitution force, location of contact on bit or drill string, and orientation of impact force.

48. The method of claim 41, wherein the graphically displaying the performance characteristic comprises graphically displaying at least one of the group consisting of bottom hole pattern, forces on bit, torque, weight on bit, imbalanced force components, total imbalanced force on bit, vector angle of total imbalanced force on bit, imbalance of forces on blade, forces on blades, radial force, circumferential force, axial force, total force on blade, vector angle of total force, imbalance of forces on blade, forces on cutters, cutter forces defined in a selected Cartesian coordinate system, radial cutter force, circumferential cutter force, axial cutter force, an angle (Beta) between the radial force component and the circumferential force component of total imbalance force, total force on cutter, vector angle of total force, imbalance of forces on cutter, back rake angle of cutter against the formation, side rake angle, cut shape on cutters, wear on cutters, and contact of bit body with formation, impact force, restitution force, location of contact on bit or drill string, and orientation of impact force.

49. The method of claim 38, wherein determining a performance characteristic of the fixed cutter drill bit comprises:

calculating the performance characteristics over a plurality of incremental portions of rotation; and

graphically displaying the performance characteristics at a selected incremental portion of calculated rotation.

50. The method of claim 38, wherein:

determining a performance characteristic comprises calculating the performance characteristic over a plurality of incremental portions of rotation; and

graphically displaying comprises displaying the performance characteristic in a sequence of displays over a series of sequential incremental portions of calculated rotation.

51. The method of claim 38, wherein the graphically the performance characteristic comprises:

displaying a calculated performance characteristic selected from the group consisting of bottom hole pattern, forces on blades, forces on cutters, cut shape on cutters, wear on cutters, and contact of bit body with earth formation.

52. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a combination of numeric values representing input parameters affecting performance calculation and performance characteristics on a single screen.

53. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of a bottomhole pattern cut into a formation by the dill bit in the earth formation.

54. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of at least one cutter spatially oriented relative to the fixed cutter drill bit, the three-dimensional graphical depiction including a cutter/formation interface contact area shape.

55. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of at least one cutter, spatially oriented relative to at least one other cutter of the fixed cutter drill bit, the three-dimensional graphical depiction including a cutter/formation interface contact area shape.

56. The method of claim 54, wherein the cutter contact/formation interface contact area shape depiction further comprises a color coded indication of force distribution on the contact area.

57. The method of claim 55, wherein the cutter contact/formation interface contact area shape depiction further comprises a color coded indication of force distribution on the contact area.

58. The method of claim 54, further comprising a graphical depiction of a force vector acting on the at least one spatially oriented cutter.

59. The method of claim 55, further comprising a graphical depiction of a force vector acting on the at least one spatially oriented cutter.

60. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of at least one cutter spatially oriented relative to the drill bit, the three-dimensional graphical depiction including a graphical depiction of cut force, and normal force vectors acting on the at least one spatially oriented cutter.

61. The method of claim 38, wherein the displaying a graphical display a performance characteristic comprises:

displaying a three-dimensional graphical depiction of a plurality of cutters of a dill bit of the calculation, the cutters depicted spatially oriented relative each other, the three-dimensional graphical depiction including a graphical depiction of a cut force vector and a normal force vector acting on the spatially oriented cutters.

62. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of the fixed cutter dill bit and a graphical depiction of a total imbalanced force vector on the fixed cutter drill bit spatially oriented relative to the fixed cutter drill bit.

63. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of the fixed cutter dill bit and a graphical depiction of a total imbalanced force vector on the fixed cutter drill bit spatially oriented relative to at least one cutter of the fixed cutter drill bit.

64. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of a fixed cutter dill bit and a graphical depiction of a total imbalance force vector on the fixed cutter drill bit, the three-dimensional graphical depiction including a radial imbalance force component and a circumferential force imbalance component, and a Beta angle between the radial imbalance force component and the circumferential force imbalance components.

65. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a graphical plot of the angle, beta, between the radial component of the total imbalance force vector on the fixed cutter drill bit and the circumferential component of the total imbalance force vector on the fixed cutter drill bit.

66. The method of claim 38, wherein the graphically displaying the performance characteristic comprises:

displaying a three-dimensional graphical depiction of a fixed cutter dill bit and a graphical depiction of a total imbalance force vector on the fixed cutter drill bit, the graphical depiction of a total imbalance force vector including a circumferential component, a radial component, and a beta angle between the radial and circumferential components spatially oriented relative to at least one cutter of the fixed cutter drill bit and depicted dynamically over a selected interval of time.

67. The method of claim 38, wherein the graphically displaying the performance characteristic comprises displaying a graphical display of the number of cutters in contact with the earth formation a given point in time.

68. The method of claim 38, wherein the graphically displaying the performance characteristic comprises displaying a graphical display of the number of cutters in contact with the earth formation at a plurality of incremental rotation intervals over a selected period of time.

69. The method of claim 38, wherein the determining a performance characteristic of the fixed cutter drill bit comprises:

solving for a response to an increment of rotation of the fixed cutter drill bit, using a mechanics analysis model of the fixed cutter drill bit on a drill string; and

repeating the solving for a select number of successive increments of rotation.

70. The method of claim 38, wherein the determining a performance characteristic of the fixed cutter drill bit comprises:

calculating an offset of a centerline of the fixed cutter drill bit from a central axis of a borehole in response to rotation of the fixed cutter drill bit on a drill string; and

repeating the calculating for a select number of successive increments of the rotation.

71. The method of claim 70, wherein the calculating an offset of a centerline of the fixed cutter drill bit from a central axis of a borehole drilled through the earth formation in response to rotation comprises:

calculating the offset of the centerline of the fixed cutter drill bit from the central axis of a borehole drilled through the earth formation in response to an increment of rotation of the fixed cutter drill bit using a mechanics analysis model.

72. The method of claim 38, wherein the graphically displaying the performance characteristic comprises displaying a graphical display of a calculated offset of the fixed cutter drill bit centerline from a central axis of a borehole drilled into the earth formation.

73. The method of claim 38, wherein the graphically displaying the performance characteristic comprises displaying a graphical display of an offset between a centerline of the fixed cutter drill bit and the central axis of a borehole drilled through the earth formation, the offset calculated for an increment of rotation of the fixed cutter drill bit using a mechanics analysis model.

74. The method of claim 73, wherein the graphically displaying the performance characteristic comprises displaying a graphical display of a calculated centerline offset at an increment of rotation of the fixed cutter drill bit.

75. The method of claim 73, wherein the graphically displaying the performance characteristic comprises displaying a historical plot of a plurality of calculated centerline offsets at a plurality of increments of rotation of the fixed cutter drill bit.

76. The method of claim 73, wherein the graphically displaying the performance characteristic comprises displaying a dynamic sequence of a plurality of calculated centerline offsets at a plurality of respective increments of rotation of the fixed cutter drill bit.

159. A fixed cutter drill bit designed by the method of claim 38.

77. A method for designing a fixed cutter drill bit, comprising:

calculating the trajectories and cut patterns of at least two cutters on separate blades of the fixed cutter drill bit, the cutters having partially overlapping trajectories such that a ridge is formed between grooves of material removed from an earth formation being drilled by the separate cutters during drilling, and

visually displaying to a design engineer, the groove portion removed by the cutters from the earth formation and the ridge formed between the grooves.

78. The method of claim 77, wherein the visually displaying comprises displaying as the design engineer is adjusting design parameters of the fixed cutter drill bit.

79. The method of claim 77, wherein the visually displaying comprises displaying as the design engineer is adjusting design parameters of the fixed cutter drill bit to reduce the size of the ridges.

160. A fixed cutter drill bit designed by the method of claim 77.

80. A method for designing a fixed cutter drill bit, comprising:

calculating the trajectories and cut patterns of a plurality of cutters of the fixed cutter drill bit, the cutters having partially overlapping trajectories such that a ridge is formed between grooves of material removed from an earth formation being drilled by the separate cutters during drilling, and

visually displaying, to a design engineer, a visual representation of a bottom hole cutting pattern, including a scaled three dimensional depiction of the cutting paths and ridges between respective cutting paths of a plurality of cutters on a leading blade and a plurality of cutters on a trailing blade.

81. The method of claim 80, wherein the visually displaying comprises displaying the visual representation of the bottom hole cutting pattern as the design engineer adjusts the design parameters of the fixed cutter drill bit.

82. The method of claim 80, wherein the visually displaying comprises displaying the visual representation of the bottom hole cutting pattern as the design engineer adjusts the design parameters of the cutters.

161. A fixed cutter drill bit designed by the method of claim 80.

83. A method for designing a fixed cutter drill bit, comprising:

calculating a cutter/formation interface area size, shape, and force vectors for each of at least two cutters on separate blades of the fixed cutter drill bit, the cutters having partially overlapping trajectories such that material removed from an earth formation being drilled by one of the at least two cutters affects the cutter/formation interface area, size, shape and force vectors of the other of the at least two separate cutters during drilling; and

visually displaying the cutter/formation interface area to a design engineer.

84. The method of claim 83, wherein the visually displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

162. A fixed cutter drill bit designed by the method of claim 83.

85. A method for designing a fixed cutter drill bit, comprising:

calculating dynamic force vectors acting upon a plurality of fixed cutters on the fixed cutter drill bit during drilling of an earth formation; and

graphically displaying, to a design engineer, the dynamic force vectors of the plurality of cutters over a selected time interval.

86. The method of claim 85, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

163. A fixed cutter drill bit designed by the method of claim 85.

87. A method for designing a fixed cutter drill bit, comprising:

calculating imbalance force vectors acting upon the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the imbalance force vectors.

88. The method of claim 87, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

164. A fixed cutter drill bit designed by the method of claim 87.

89. A method for designing a fixed cutter drill bit, comprising:

calculating imbalance force vectors acting upon the fixed cutter drill bit during drilling through an earth formation, including components of circumferential imbalance force and radial imbalance force and an angle, Beta, between the imbalance for components; and

graphically displaying, to a design engineer, the imbalance force vectors.

90. The method of claim 89, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

165. A fixed cutter drill bit designed by the method of claim 89.

91. A method for designing a fixed cutter drill bit, comprising:

calculating imbalance force vectors acting upon the fixed cutter drill bit during drilling through an earth formation, including components of circumferential imbalance force and radial imbalance force and an angle, Beta, between the components of the imbalance force; and

graphically displaying, to a design engineer, a historic plot of the angle, Beta, between the components of the imbalance force vector over a selected time interval.

92. The method of claim 91, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

166. A fixed cutter drill bit designed by the method of claim 91.

93. A method for designing a fixed cutter drill bit, comprising:

calculating an angle, Beta, between components of an imbalance force acting on the fixed cutter drill bit drilling through an earth formation; and

graphically displaying, to a design engineer, the angle, Beta, between the components of the imbalance force at selected time interval.

94. The method of claim 93, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

167. A fixed cutter drill bit designed by the method of claim 93.

95. A method for designing a fixed cutter drill bit, comprising:

calculating a force acting upon each of a plurality of blades of the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the calculated force on each of the plurality of blades at a selected time interval.

96. The method of claim 95, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

168. A fixed cutter drill bit designed by the method of claim 95.

97. A method for designing a fixed cutter drill bit, comprising:

calculating forces acting upon a plurality of blades of the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the calculated force on each of the plurality of blades over a selected time interval, corresponding to a number of incremental portions of calculated rotation at a selected rotation speed.

98. The method of claim 97, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

169. A fixed cutter drill bit designed by the method of claim 97.

99. A method for designing a fixed cutter drill bit, comprising:

calculating forces acting upon a plurality of cutters of the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the calculated force on each of the plurality of blades at a selected time interval.

100. The method of claim 99, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

170. A fixed cutter drill bit designed by the method of claim 99.

101. A method for designing a fixed cutter drill bit, comprising:

calculating forces acting upon a plurality of cutters of the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the calculated force on each of the plurality of cutters over a selected time interval.

102. The method of claim 101, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

171. A fixed cutter drill bit designed by the method of claim 101.

103. A method for designing a fixed cutter drill bit, comprising:

calculating a wear pattern on a plurality of cutters on the fixed cutter drill bit over a selected time interval;

graphically displaying, to a design engineer, the wear pattern on the plurality of cutters.

104. The method of claim 103, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

172. A fixed cutter drill bit designed by the method of claim 103.

105. A method for designing a fixed cutter drill bit, comprising:

calculating force vectors acting upon at least one cutter on the fixed drill bit during drilling through a transition between different layers of an earth formation; and

graphically displaying, to a design engineer, the dynamic force vectors at a selected depth through the transition.

106. The method of claim 105, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

173. A fixed cutter drill bit designed by the method of claim 105.

107. A method for designing a fixed cutter drill bit, comprising:

calculating dynamic force vectors acting upon at least one cutter on the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the dynamic force vectors over a selected time interval.

108. The method of claim 107, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

174. A fixed cutter drill bit designed by the method of claim 107.

109. A method for designing a fixed cutter drill bit, comprising:

calculating dynamic force vectors acting upon a plurality of cutters on the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the dynamic force vectors over a selected time interval.

110. The method of claim 109, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

175. A fixed cutter drill bit designed by the method of claim 109.

111. A method for designing a fixed cutter drill bit, comprising:

calculating dynamic force vectors acting upon at least one cutter on the fixed cutter drill bit during drilling through a transition between a plurality of different layers of an earth formation; and

graphically displaying, to a design engineer, the dynamic force vectors over a selected time interval.

112. The method of claim 111, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

176. A fixed cutter drill bit designed by the method of claim 111.

113. A method for designing a fixed cutter drill bit, comprising:

calculating dynamic force vectors acting upon a plurality of cutters on the fixed cutter drill bit during drilling through a transition between a plurality of different layers of an earth formation; and

graphically displaying, to a design engineer, the dynamic force vectors over a selected time interval.

114. The method of claim 113, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

177. A fixed cutter drill bit designed by the method of claim 113.

115. A method for designing a fixed cutter drill bit, comprising:

calculating the rate of penetration of the fixed cutter drill bit during drilling through an earth formation; and

graphically displaying, to a design engineer, the calculated rate of penetration at a selected time interval.

116. The method of claim 115, wherein the graphically displaying comprises displaying as the design engineer adjusts design parameters of the fixed cutter drill bit.

178. A fixed cutter drill bit designed by the method of claim 115.

117. A method for designing a fixed cutter drill bit, comprising:

calculating a plurality of performance characteristics of the fixed cutter drill bit selected form the group comprising;

trajectories and cut patterns of at least two cutters on separate blades of a fixed cutter drill bit, the cutters having partially overlapping trajectories such that a ridge is formed between grooves of material removed from an earth formation being drilled by the separate cutters during drilling;

a cutter/formation interface area size, shape, and force vectors for each of at least two cutters on separate blades of the fixed cutter drill bit, the cutters having partially overlapping trajectories such that material removed from an earth formation being drilled by one of the at least two cutters affects the cutter/formation interface area, size, shape and force vectors of the other of the at least two separate cutters during drilling;

imbalance force vectors acting upon a fixed cutter drill bit during drilling through an earth formation;

imbalance force vectors acting upon the fixed cutter drill bit during drilling through an earth formation, including components of circumferential imbalance force and radial imbalance force and an angle, Beta, between the imbalance for components;

Beta angle, between components of an imbalance force acting on the fixed cutter drill bit drilling through an earth formation;

forces acting upon a plurality of blades of a fixed cutter drill bit during drilling through an earth formation;

forces acting upon a plurality of cutters of the fixed cutter drill bit during drilling through an earth formation;

wear pattern on a plurality of cutters on the fixed cutter drill bit over a selected time interval;

force vectors acting upon at least one cutter on the fixed drill bit during drilling through a transition between different layers of an earth formation;

dynamic force vectors acting upon at least one cutter on the fixed cutter drill bit during drilling through an earth formation;

dynamic force vectors acting upon a plurality of cutters on the fixed cutter drill bit during drilling through an earth formation;

dynamic force vectors acting upon at least one cutter on the fixed cutter drill bit during drilling through a transition between a plurality of different layers of an earth formation;

dynamic force vectors acting upon a plurality of cutters on the fixed cutter drill bit during drilling through a transition between a plurality of different layers of an earth formation; and

selectively graphically displaying, to a design engineer, the plurality of calculated performance characteristics of the fixed cutter drill bit, as the design engineer adjusts design parameters.

118. The method of claim 117, wherein the selectively displaying further comprised toggling by the design engineer between two or more of the plurality of calculated parameters and characteristics of the fixed cutter drill bit, as the design engineer adjusts design parameters.

179. A fixed cutter drill bit designed by the method of claim 117.

119. A method for designing a fixed cutter drill bit, comprising:

simulating one or more performance characteristics of a fixed cutter drill bit with the fixed cutter drill bit drilling in an earth formation;

displaying a graphical display of at least one of the one or more simulated performance characteristics, together with a visual display representing at least one fixed cutter drill bit design parameter;

adjusting a value of at least one fixed cutter drill bit design parameter; and

repeating the adjusting, the simulating and the displaying to optimize the at least one of the one or more drilling performance characteristics.

120. The method of claim 119, wherein the visual display representing the at least one fixed cutter drill bit design parameter comprises a graphical display.

121. The method of claim 119, wherein simulating one or more performance characteristics of the fixed cutter drill bit further comprises:

simulating the one or more performance characteristics at a plurality of increments of simulated fixed cutter drill bit rotation.

122. The method of claim 119, wherein simulating one or more performance characteristics of the fixed cutter drill bit further comprises selecting one or more parameters affecting performance selected from among the group consisting of control model type parameters, drill string design parameters, fixed cutter drill bit design parameters, earth formation parameters, drill bit/formation interface configuration parameters, and drilling operating parameters.

123. The method of claim 122, wherein the control model type parameters comprise, cutter/formation control model, weight on bit (WOB) control model, and rate of penetration control (ROP) control model, constrained centerline model, and dynamic model.

124. The method of claim 122, wherein the drill string design parameters comprise number of components, type of components, material of components, length, strength and elasticity of components, O.D. of components, I.D. of components, nodal division of components, type of down hole assembly, length, strength, elasticity, density, density in mud, O.D. and I.D. of down hole assembly, hook load, drill bit type, drill bit design parameters, length, diameter, strength, elasticity, O.D., I.D. and wear model of drill bit, number of blades, orientation of blades, shape, size strength, elasticity, OD, ID and wear model of blades.

125. The method of claim 122, wherein the drill bit design parameters comprise number of cutters, bit cutting profile, position of cutters on drill bit blades, bit axis offset of the cutter, bit diameter, cutter radius on bit, cutter vertical height on bit, cutter inclination angle on bit, cutter body shape, cutter size, cutter height, cutter diameter, cutter orientation, cutter back rake angle, cutter side rake angle, working surface shape, working surface orientation, cutter hardness, PDC table thickness, and cutter wear model.

126. The method of claim 122, wherein the earth formation parameters comprise at least one of a group consisting of formation layer type, formation mechanical strength, formation density, formation wear characteristics, formation non-homogeneity, formation anisotropic strength, wear characteristics and orientation, borehole diameter, empirical test data for earth formation type, multiple layer formation interfaces, formation layer depth, formation layer interface angle, formation layer interface orientation, and empirical test data for multiple layer interface.

127. The method of claim 122, wherein the drilling operation parameters comprise at least one of the group consisting of weight on bit, bit torque, rate of penetration, rotary speed, rotating time, wear flat area, hole diameter, mud type, mud density, vertical drilling, drilling tilt angle, platform/table rotation, directional drilling, down hole motor rotation, bent drill string rotation, and side load.

128. The method of claim 122, wherein the drilling performance characteristics comprise at least one of a group consisting of bottom hole pattern, forces on bit, torque, weight on bit, imbalanced force components in a selected Cartesian coordinate system, total imbalanced force on bit, vector angle of total imbalanced force on bit, imbalance of forces on blade, forces on blades, forces defined in a selected Cartesian coordinate system, radial force (normal force), circumferential force (tangential force), axial force (vertical force), total force on blade, vector angle of total force, imbalance of forces on blade, forces on cutters, cutter forces defined in a selected Cartesian coordinate system, radial cutter force (normal force), circumferential cutter force (tangential force), axial cutter force (vertical force), an angle (Beta) between the radial force component and the circumferential force component of total imbalance force, total force on cutter, vector angle of total force, imbalance of forces on cutter, back rake angle of cutter against the formation, side rake angle, cut shape on cutters, wear on cutters, and contact of bit body with formation, impact force, restitution force, location of contact on bit or drill string, and orientation of impact force.

129. The method of claim 119, wherein the one or more performance characteristic simulated being selected from at least one of the group consisting of bottom hole pattern, forces on bit, torque, weight on bit, imbalanced force components in a selected Cartesian coordinate system, total imbalanced force on bit, vector angle of total imbalanced force on bit, imbalance of forces on blade, forces on blades, forces defined in a selected Cartesian coordinate system, radial force (normal force, x ordinate), tangential force (circumferential force, y ordinate), vertical force (axial force, z ordinate), total force on blade, vector angle of total force on blade, imbalance of forces on blade, forces on cutters, forces on the cutter defined in a selected Cartesian coordinate system, normal cutter force (Fn) cutting force (Fc), side force (Fs), total force on cutter (Ft), vector angle of total force, imbalance of forces on cutter, back rake angle of cutter against the formation, side rake angle, cut shape on cutters, wear on cutters, and contact of bit body with formation, impact force, restitution force, location of contact on bit or drill string, and orientation of impact force.

130. The method of claim 119 wherein simulating one or more performance characteristics of the drill bit further comprises simulating the one or more performance characteristics over a plurality of incremental portions of simulated drill bit rotation.

131. The method of claim 119 wherein simulating one or more performance characteristics of the drill bit further comprises:

simulating the one or more performance characteristics over a plurality of incremental portions of simulated drill bit rotation; and

displaying a graphical display of at least one of the one or more simulated performance characteristics comprises displaying the at least one performance characteristic at a selected incremental portion of simulated rotation.

132. The method of claim 119 wherein simulating one or more performance characteristics of the drill bit further comprises:

simulating the one or more performance characteristics over a plurality of incremental portions of simulated drill bit rotation; and

displaying a graphical display of at least one of the one or more simulated performance characteristics comprises displaying the at least one performance characteristic in a timed sequence of displays over a series of sequential incremental portions of simulated rotation.

133. The method of claim 119, wherein the displaying of at least one performance characteristic comprises

displaying a simulated performance characteristic selected from among the group of bottom hole pattern, forces on blades, forces on cutters, cut shape on cutters, wear on cutters, and contact of bit body with earth formation.

134. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a combination of numeric values representing all input parameters affecting performance simulation and all simulated performance characteristics on a single screen after a pre-selected simulated rotation of the drill bit.

135. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of a bottomhole pattern cut into a formation by the dill bit in the earth formation.

136. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of at least one cutter of a dill bit of the simulation spatially oriented relative to the drill bit, the three-dimensional graphical depiction including a cutter/formation interface contact area shape.

137. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of at least one cutter, of a dill bit of the simulation, spatially oriented relative to at least one other cutter of the drill bit of the simulation, the three-dimensional graphical depiction including a cutter/formation interface contact area shape.

138. The method of claim 137, wherein the cutter contact/formation interface contact area shape depiction further comprises a color coded indication of force distribution on the contact area.

139. The method of claim 138, wherein the cutter contact/formation interface contact area shape depiction further comprises a color coded indication of force distribution on the contact area.

140. The method of claim 137, further comprising a graphical depiction of a force vector acting on the at least one spatially oriented cutter.

141. The method of claim 138, further comprising a graphical depiction of a force vector acting on the at least one spatially oriented cutter.

142. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of at least one cutter of a dill bit of the simulation spatially oriented relative to the drill bit, the three-dimensional graphical depiction including a graphical depiction of cut force, and normal force vectors acting on the at least one spatially oriented cutter.

143. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of a plurality of cutters of a dill bit of the simulation, the cutters depicted spatially oriented relative each other, the three-dimensional graphical depiction including a graphical depiction of a cut force vector and a normal force vector acting on the spatially oriented cutters.

144. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of a dill bit of the simulation and a graphical depiction of a total imbalanced force vector on the drill bit, spatially oriented relative to the drill bit.

145. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises;

displaying a three-dimensional graphical depiction of a dill bit of the simulation and a graphical depiction of a total imbalanced force vector on the drill bit, spatially oriented relative to at least one cutter of the drill bit.

146. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of a dill bit of the simulation and a graphical depiction of a total imbalance force vector on the drill bit, the three-dimensional graphical depiction including a radial imbalance force component and a circumferential force imbalance component, and a beta angle between the radial imbalance force component and the circumferential force imbalance components.

147. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a graphical plot of the angle, beta, between the radial component of the total imbalance force vector on the drill bit and the circumferential component of the total imbalance force vector on the drill bit.

148. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises:

displaying a three-dimensional graphical depiction of a dill bit of the simulation and a graphical depiction of a total imbalance force vector on the drill bit, the graphical depiction of a total imbalance force vector including a circumferential component, a radial component, and a beta angle between the radial and circumferential components spatially oriented relative to at least one cutter of the drill bit and depicted dynamically over a selected interval of time, corresponding to a sequence of a number of incremental portions of rotation.

149. The method of claim 119, wherein the simulating comprises,

solving for the dynamic response of the drill bit to an incremental rotation using a mechanics analysis model, and

repeating said solving for a select number of successive incremental rotations

150. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises displaying a graphical display of the number of cutters in contact with the earth formation a given point in time during simulated drilling.

151. The method of claim 119, wherein the displaying a graphical display of at least one performance characteristic comprises displaying a graphical display of the number of cutters in contact with the earth formation at a plurality of incremental rotation intervals over a selected period of time during simulated drilling.

180. A fixed cutter drill bit designed by the method of claim 119.

152. A method for designing a fixed cutter drill bit, comprising:

simulating a dynamic performance of the fixed cutter drill bit drilling into a borehole without the centerline of the fixed cutter drill bit constrained into alignment with the centerline of the borehole;

displaying a visual display of at least one characteristic of the simulated performance; and

adjusting a value of at least one design parameter for a fixed cutter bit assembly according to the visual display.

153. The method of claim 152, comprising repeating the simulating, the displaying and the adjusting to change the characteristic of the simulated performance.

154. The method of claim 153, the characteristic of performance is changed to optimize the characteristic of the simulated performance.

155. A method for designing a fixed cutter bit assembly of claim 152, wherein the displaying comprises displaying a characteristic of the dynamic performance over a selected time interval.

181. A fixed cutter drill bit designed by the method of claim 152.

156. A method of designing a fixed cutter drill bit, comprising:

(a) inputting drill bit design parameters;

(b) simulating drilling an earth formation in accordance with the input drill bit design parameters to obtain at least one performance characteristic;

(c) graphically displaying the at least one of the performance characteristic;

(d) adjusting a drill bit design parameter in accordance with the at least one of the performance characteristics displayed;

(e) simulating drilling an earth formation in accordance with the input drill bit design parameters adjusted in accordance with step (d) to obtain adjusted performance characteristics;

(f) graphically displaying at least one of the adjusted performance characteristics;

(g) repeating the steps (d), (e), and (f), until a pre-selected criteria for a simulated performance characteristic is obtained.

157. The method of claim 156, wherein the pre-selected criteria is the optimum performance of a selected performance characteristic.

182. A fixed cutter drill bit designed by the method of claim 156.