Method for designing cutting structure for roller cone drill bits
First Claim
1. A roller cone drill bit for drilling an earth formation, comprising:
- a bit body;
three roller cones attached to the bit body and able to rotate with respect to the bit body; and
a plurality of cutting elements arranged on each of the roller cones so that cutting elements on adjacent cones intermesh between the adjacent cones, the cutting elements being arranged such that axial force exerted on the bit during drilling is substantially balanced between the cones, wherein the axial force on the cones is determined by selecting bit design parameters, comprising at least a geometry of a cutting element on said bit;
selecting drilling parameters, comprising at least an axial force on said bit;
selecting an earth formation to be represented as drilled;
calculating from said selected drilling parameters, said selected bit design parameters and said earth formation, parameters for a crater formed when one of a plurality of said cutting elements contacts said earth formation;
calculating a bottomhole geometry, wherein said crater is removed from a bottomhole surface;
simulating incrementally rotating said bit, and repeating said calculating of said crater parameters and said bottomhole geometry, based on calculated roller cone rotation speed and geometrical location with respect to rotation of said roller cone drill bit about its axis; and
summing axial force developed by each of said cutting elements in creating said craters.
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Abstract
New cutting structures for roller cone drill bits are disclosed. In one aspect, a drill bit includes a bit body, roller cones attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on each of the roller cones, such that axial force on the bit during drilling is substantially balanced between the cones. In another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that the amount of work performed by each cone during drilling is substantially the same as the amount of work performed by each of the other cones. In yet another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that distribution of axial force on the bit is optimized. Additional aspects of the invention are also disclosed.
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Citations
136 Claims
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1. A roller cone drill bit for drilling an earth formation, comprising:
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a bit body;
three roller cones attached to the bit body and able to rotate with respect to the bit body; and
a plurality of cutting elements arranged on each of the roller cones so that cutting elements on adjacent cones intermesh between the adjacent cones, the cutting elements being arranged such that axial force exerted on the bit during drilling is substantially balanced between the cones, wherein the axial force on the cones is determined by selecting bit design parameters, comprising at least a geometry of a cutting element on said bit;
selecting drilling parameters, comprising at least an axial force on said bit;
selecting an earth formation to be represented as drilled;
calculating from said selected drilling parameters, said selected bit design parameters and said earth formation, parameters for a crater formed when one of a plurality of said cutting elements contacts said earth formation;
calculating a bottomhole geometry, wherein said crater is removed from a bottomhole surface;
simulating incrementally rotating said bit, and repeating said calculating of said crater parameters and said bottomhole geometry, based on calculated roller cone rotation speed and geometrical location with respect to rotation of said roller cone drill bit about its axis; and
summing axial force developed by each of said cutting elements in creating said craters. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for designing a roller cone drill bit having a plurality of roller cones and initial design parameters, comprising:
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simulating drilling with the bit and determining for each of the roller cones as a result of the simulating, a distribution of time that each of a number of cutting elements is in contact with an earth formation being simulated as drilled;
adjusting at least one of the initial design parameters;
repeating the simulating drilling; and
repeating the adjusting, the simulating and the determining until the distribution of time is substantially the same for each one of the roller cones. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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46. A method for designing a roller cone drill bit having a plurality of roller cones and initial design parameters, comprising:
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simulating drilling an earth formation with the bit and determining as a result of the simulating, a distribution of axial force on the bit;
adjusting at least one of the initial design parameters;
repeating the simulating drilling; and
repeating the adjusting, the simulating and the determining until the distribution of axial force is optimized. - View Dependent Claims (47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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61. A method for designing a roller cone drill bit having a plurality of roller cones and initial design parameters, comprising:
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simulating drilling an earth formation with the bit and determining for each of the roller cones as a result of the simulating, a work performed by each roller cone;
adjusting at least one of the initial design parameters;
repeating the simulating drilling; and
repeating the adjusting, the simulating and the determining until the work performed is substantially the same for each one of the roller cones. - View Dependent Claims (62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75)
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76. A method for designing a roller cone drill bit having a plurality of roller cones and initial design parameters, comprising:
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simulating drilling an earth formation with the bit and determining for each of the roller cones as a result of the simulating, a projected area of contact of cutting elements on each roller cone with the earth formation;
adjusting at least one of the initial design parameters;
repeating the simulating drilling; and
repeating the adjusting, the simulating and the determining until the projected area is substantially the same for each one of the roller cones. - View Dependent Claims (77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90)
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91. A method for designing a roller cone drill bit having a plurality of roller cones and initial design parameters, comprising:
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simulating drilling an earth formation with the bit and determining for each of the roller cones as a result of the simulating, a depth of penetration of cutting elements on each roller cone with the earth formation;
adjusting at least one of the initial design parameters;
repeating the simulating drilling; and
repeating the adjusting, the simulating and the determining until the depth of penetration is substantially the same for each one of the roller cones. - View Dependent Claims (92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105)
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106. A method for designing a roller cone drill bit having a plurality of roller cones and initial design parameters, comprising:
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simulating drilling an earth formation with the bit and determining for each of the roller cones as a result of the simulating, an axial force acting on each row of cutting elements;
adjusting at least one of the initial design parameters;
repeating the simulating drilling; and
repeating the adjusting, the simulating and the determining until the axial force acting on corresponding rows of cutting elements on each of the roller cones is substantially the same. - View Dependent Claims (107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120)
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121. A method for designing a roller cone drill bit having a plurality of roller cones and initial design parameters, comprising:
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simulating drilling an earth formation with the bit and determining for each of the roller cones as a result of the simulating, an axial force acting on each one of the cutting elements;
adjusting at least one of the initial design parameters;
repeating the simulating drilling; and
repeating the adjusting, the simulating and the determining until the axial force acting on corresponding cutting elements on each of the roller cones is substantially the same. - View Dependent Claims (122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136)
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Specification