Roller-cone bits, systems, drilling methods, and design methods with optimization of tooth orientation
First Claim
1. A method of designing a roller cone bit, comprising the steps of:
- adjusting the orientation of at least one tooth on a cone, in dependence on an expected trajectory of said tooth through formation material at the cutting face, in dependence on an estimated ratio of cone rotation to bit rotation;
recalculating said ratio, if the location of any row of teeth on said cone changes during optimization;
recalculating the trajectory of said tooth in accordance with a recalculated value of said cone speed; and
adjusting the orientation of said tooth again, in accordance with a recalculated value of said tooth trajectory.
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Accused Products
Abstract
A novel and improved roller cone drill bit and method of design are disclosed. A roller cone drill bit for drilling through subterranean formations having an upper connection for attachment to a drill string, and a plurality cutting structures rotatably mounted on arms extending downward from the connection. A number of teeth are located in generally concentric rows on each cutting structure. The actual trajectory by which the teeth engage the formation is mathematically determined. A straight-line trajectory is calculated based on the actual trajectory. The teeth are positioned in the cutting structures such each tooth having a designed engagement surface is oriented perpendicular to the calculated straight-line trajectory.
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Citations
21 Claims
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1. A method of designing a roller cone bit, comprising the steps of:
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adjusting the orientation of at least one tooth on a cone, in dependence on an expected trajectory of said tooth through formation material at the cutting face, in dependence on an estimated ratio of cone rotation to bit rotation;
recalculating said ratio, if the location of any row of teeth on said cone changes during optimization;
recalculating the trajectory of said tooth in accordance with a recalculated value of said cone speed; and
adjusting the orientation of said tooth again, in accordance with a recalculated value of said tooth trajectory. - View Dependent Claims (2, 3, 15, 20, 21)
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4. A method of designing a roller cone bit, comprising the steps of:
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calculating the trajectory of at least one tooth on each cone through formation material at the cutting face; and
jointly optimizing both the orientations of said teeth and the width of uncut rings on said cutting face, in dependence on said trajectory. - View Dependent Claims (5, 16)
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6. A method of designing a roller cone bit comprising the steps of:
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a) adjusting the orientation of at least one row of teeth on a cone, in dependence on an expected trajectory of said tooth through formation material at the cutting face;
b) calculating the width of uncut rings of formation material, in dependence on the orientation of said row of teeth, and adjusting the position of said row of teeth in dependence on said calculated width; and
c) recalculating the rotational speed of said cone, if the position of said row is changed, and accordingly recalculating said trajectory of teeth in said row. - View Dependent Claims (7, 8, 17)
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9. A method of designing a roller cone bit, comprising the steps of:
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calculating the respective trajectories, of at least two non-axisymmetric teeth in different rows of a roller cone bit, through formation material at the cutting face; and
graphically displaying, to a design engineer, both said trajectories and also respective orientation vectors of said teeth, as the engineer adjusts design parameters. - View Dependent Claims (10, 18)
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11. A method of designing a roller cone bit, comprising the steps of:
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calculating the curved trajectory of a non-axisymmetric tooth through formation material at the cutting face, as the bit and cones rotate;
calculating a straight line approximation to said curved trajectory; and
orienting said tooth with respect to said approximation, and not with respect to said curved trajectory. - View Dependent Claims (12, 13, 14, 19)
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Specification