Cutting structure for earth boring drill bits

A drill bit for drilling a borehole, the drill bit comprising a bit body having an axis of rotation, a leading face, a plurality of blades upstanding from the leading face, at least two of the blades terminating in gauge pads, the gauge pads interconnected to form a continuous a gauge surface arranged, in use, to face a wall of the borehole, the gauge surface being devoid of cutting elements, the gauge surface terminating at an end thereof remote from the blade at a junction with an end wall, wherein the gauge pad carries a cutter having a face and a cutting edge located radially inward of the gauge surface, the radial spacing of the cutting edge from the gauge surface being greater than about 0.15 mm.

A drill bit for drilling a borehole, the drill bit comprising a bit body having an axis of rotation, a leading face, a plurality of blades upstanding from the leading face, at least two of the blades terminating in gauge pads, the gauge pads interconnected to form a continuous a gauge surface arranged, in use, to face a wall of the borehole, the gauge surface being devoid of cutting elements, the gauge surface terminating at an end thereof remote from the blade at a junction with an end wall, wherein the gauge pad carries a cutter having a face and a cutting edge located radially inward of the gauge surface, and wherein a notional line between the junction and the cutting edge makes an angle with the axis of rotation of less than about 0.1°.

A drill bit for drilling a borehole, the drill bit comprising a bit body having an axis of rotation, a leading face, a plurality of blades upstanding from the leading face, at least two of the blades terminating in gauge pads, the gauge pads interconnected to form a continuous gauge surface arranged, in use, to face a wall of the borehole, the gauge surface being devoid of cutting elements, the gauge surface terminating at an end thereof remote from the blade at a junction with an end wall, wherein the gauge pad carries a cutter having a face and a cutting edge located radially inward of the gauge surface, and wherein an axial position of the junction of the gauge surface and the pad end wall lies between an axial position of an edge of the cutter face closest to the blade and an edge thereof furthest from the blade.

A steerable drilling system for use in the drilling of a borehole comprising a bottom hole assembly adapted to permit control over the direction of drilling of a drill bit, the drill bit comprising a bit body having a plurality of blades, at least two of the blades terminating in gauge pads, the gauge pads interconnected to form a continuous gauge surface arranged, in use, to face a wall of the borehole, the gauge surface being devoid of cutting elements, the gauge surface terminating at an end thereof remote from the blade at a junction with an end wall, wherein the gauge pad carries a cutter located inward of the gauge surface and such that an axial position of a junction between the gauge surface and the end wall lies between an axial position of an edge of the cutter closest to the blade and an axial position of an edge of the cutter furthest from the blade.

A drill bit for drilling a borehole, the drill bit comprising a bit body having an axis of rotation, a leading face, a plurality of blades upstanding from the leading face, and a continuous gauge surface extending around the bit body and arranged, in use, to face a wall of the borehole, the gauge surface being devoid of cutting elements, the gauge surface terminating at an edge thereof remote from the blades at a junction with a gauge pad end wall, wherein the bit body carries a plurality of cutters each having a face and a cutting edge located radially inward of the gauge surface, and wherein the junction of the gauge surface and the gauge pad end wall crosses, radially, between the face of each cutter and the wall of the borehole.