Force-balanced roller-cone bits, systems, drilling methods, and design methods
First Claim
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1. A method for determining an axial force acting on each one of a plurality of roller cones on a roller cone drill bit during drilling, comprising:
- calculating, from a geometry of cutting elements on each of the roller cones and an earth formation being drilled by the drill bit, an axial force acting on each of the cutting elements;
incrementally rotating the bit and recalculating the axial forces acting on each of the cutting elements;
repeating the incrementally rotating and recalculating for a selected number of incremental rotations; and
combining the axial force acting on the cutting elements on each one of the roller cones.
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Abstract
Roller cone drilling wherein the bit optimization process equalizes the downforce (axial force) for the cones (as nearly as possible, subject to other design constraints). Bit performance is significantly enhanced by equalizing downforce.
90 Citations
28 Claims
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1. A method for determining an axial force acting on each one of a plurality of roller cones on a roller cone drill bit during drilling, comprising:
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calculating, from a geometry of cutting elements on each of the roller cones and an earth formation being drilled by the drill bit, an axial force acting on each of the cutting elements;
incrementally rotating the bit and recalculating the axial forces acting on each of the cutting elements;
repeating the incrementally rotating and recalculating for a selected number of incremental rotations; and
combining the axial force acting on the cutting elements on each one of the roller cones. - View Dependent Claims (2, 3, 4)
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5. A method for determining a volume of formation cut by each one of a plurality of roller cones on a drill bit drilling in earth formations, comprising:
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selecting bit design parameters, comprising at least a geometry of a cutting element on the drill bit;
selecting an earth formation;
calculating from the selected bit design parameters and the selected earth formation, parameters for a crater formed when each one of a plurality of cutting elements on each of the roller cones contacts the earth formation, the parameters including at least a volume of the crater;
incrementally rotating the bit, and repeating the calculating of the crater parameters for a selected number of incremental rotations; and
combining the volume of each crater formed by each of the cutting elements on each of the roller cones to determine the volume of formation cut by each of the roller cones. - View Dependent Claims (6, 7, 8, 9)
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10. A method for balancing axial forces acting on each one of a plurality of roller cones on a roller cone drill bit during drilling, comprising:
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calculating, from a geometry of cutting elements on each of the roller cones and an earth formation being drilled by the drill bit, an axial force acting on each of the cutting elements;
incrementally rotating the bit and recalculating the axial forces acting on each of the cutting elements;
repeating the incrementally rotating and recalculating for a selected number of incremental rotations;
combining the axial force acting on the cutting elements on each one of the roller cones; and
adjusting at least one bit design parameter, and repeating the calculating the axial force, incrementally rotating and combining the axial force, until a difference between the combined axial force on each one of the roller cones is less than a difference between the combined axial force determined prior to adjusting the at least one initial design parameter. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for balancing a volume of formation cut by each one of a plurality of roller cones on a drill bit drilling in earth formations, comprising:
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selecting bit design parameters, comprising at least a geometry of a cutting element on the drill bit;
selecting an earth formation;
calculating from the selected bit design parameters and the selected earth formation, parameters for a crater formed when each one of a plurality of cutting elements on each of the roller cones contacts the earth formation, the parameters including at least a volume of the crater;
incrementally rotating the bit, and repeating the calculating of the crater parameters for a selected number of incremental rotations;
combining the volume of each crater formed by each of the cutting elements on each of the roller cones to determine the volume of formation cut by each of the roller cones; and
adjusting at least one of the bit design parameters, and repeating the calculating the crater volume, incrementally rotating and combining the volume until a difference between the combined volume cut by each of the cones is less than the combined volume determined prior to the adjusting the at least one of the bit design parameters. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A method for optimizing a design of a roller cone drill bit, comprising:
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simulating the bit drilling through a selected earth formation;
adjusting at least one design parameter of the bit;
repeating the simulating the bit drilling; and
repeating the adjusting and simulating until an optimized design is determined. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification