Importance

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Abstract

A PDC bit for cutting a hole below a point in a formation, the diameter of the hole being greater than the diameter of the hole above the point, comprising: a bit body having an axis of rotation, a first cutting portion having a first radial extent from the axis of rotation, a second cutting portion that is not axially spaced apart from the first cutting portion and that has a second radial extent that is greater than said first radial extent, wherein the total imbalance forces resulting from engagement of said first and said second cutting portions with the formation are balanced such that the resulting torque on the bit is minimized and in particular, the component of the torque on the bit about an axis normal to the axis of rotation is minimized. In some embodiments, the bit has a central recessed portion on its face, which receives a short 'core' portion that enhances stabilization of the bit.

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First Claim