Anti-Tracking Spear Points for Earth-Boring Drill Bits

A roller cone bit comprising:

• a plurality of non-axially-symmetric teeth mounted on rotatable elements, one of the rotatable elements comprising a spearpoint at its apex having a plurality of cutting teeth arranged about the central axis of rotation of the rotatable element and of the spearpoint, wherein ones of the cutting teeth which follow the same path on a cutting face have different axial orientations;
• wherein a first plurality of the cutting teeth are contiguous and all have a first orientation, and a second plurality of the cutting teeth are contiguous and all have a second orientation, the first and second orientations being asymmetric about the central axis of rotation of the rotatable element;
• and
• whereby the likelihood of bit tracking is reduced.

A bit for downhole rotary drilling, comprising:

• a plurality of roller cones, each cone being rotatably mounted on a bit body;
• a plurality of cutting elements on each of the cones;
• and
• a spearpoint at the apex of one of the cones comprising a plurality of cutting elements surrounding a central axis of rotation of the cone and the spearpoint;
• wherein at least one of the cutting elements on the spearpoint being non-asymmetrically oriented with respect to at least one other cutting element;
• and
• wherein an angle between at least two of the non-asymmetrically oriented cutting elements on the spearpoint, relative to the axis of rotation of the cone on which the spearpoint is disposed is selected to reduce the bit tracking drilling performance parameter.

A rotary drilling system for use in drilling a subterranean formation, the system comprising:

• a drill string which is connected to a drill bit;
• and
• a rotary drive which rotates at least part of the drill string together with the bit;
• wherein the bit comprises:
• a plurality of rotatable elements mounted to roll along a cutting face when the drill bit is rotated under load, each of the rotatable element having teeth thereon;
• a spearpoint at the apex of one of the rotatable elements comprising a plurality of cutting elements surrounding a central axis of rotation of the rotatable element and the spearpoint;
• wherein at least one of the cutting elements on the spearpoint is non-asymmetrically oriented with respect to at least one other cutting element;
• and
• wherein an angle between at least two of the non-asymmetrically oriented cutting elements on the spearpoint, relative to the axis of rotation of the rotatable element on which the spearpoint is disposed.

A rotatable cone for use with a roller cone drill bit, the cone comprising:

• a plurality of cutting elements arranged on the exterior of the cone;
• and
• a spearpoint at the apex of the cone, the spearpoint comprising a plurality of cutting elements surrounding a central axis of rotation of the cone and the spearpoint;
• wherein at least one of the cutting elements on the spearpoint being non-asymmetrically oriented with respect to at least one other cutting element on the spearpoint.