An earth-boring tool for drilling a subterranean formation includes a bit body having a central axis and a cavity extending into the bit body from an outer surface thereof. A bearing element assembly may be mounted within the cavity. The bearing element assembly comprises a lower retaining member, an upper retaining member mounted over to the lower retaining member, the upper retaining member comprising an aperture formed therethrough, and a spherical bearing element disposed over the lower retaining member and extending through the aperture formed through the upper retaining member. The spherical bearing element is rotatable about three axes of rotation within the lower retaining member and the upper retaining member.

Various drill bits, drilling systems and related methods are provided. In one embodiment, a drill bit comprises a bit body having a face and a shank, at least one insert having a convex engagement surface coupled with the face and at least one wear insert coupled with the shank. In one particular embodiment, the at least one wear insert may be positioned immediately adjacent a coupling end of the shank. The at least one wear insert may include a superabrasive table which may be bonded with a substrate. The at least one wear insert includes a wear surface defined in the superabrasive table. In one embodiment, the superabrasive table may comprise polycrystalline diamond. Similarly, the inset having a convex engagement surface may include a superabrasive material, such as polycrystalline diamond, bonded with a substrate. Such a drill bit may be used, for example, in a top hammer percussion drilling operation.

A method includes positioning at least one guide projection on a substrate of a metal part such that the at least one guide projection extends outwardly from an outer surface of the substrate to an exposed length. Hardfacing is then applied to the substrate of the metal part at or near a location of the at least one guide projection. The exposed length of the at least one guide projection is then referenced in determining when to cease application of the hardfacing.

An expandable reamer for a borehole has a plurality of support elements (202) distributed around a central axis of the tool with cutters (234, 236) and stabilising pads (250) on the support elements, arranged such that at least one of the support elements comprises at least one region comprising cutters and at least one support element comprises a stabilising pad having a front surface positioned to face the wall of the borehole. The reamer includes drive mechanism for expanding the support elements (202) radially outwardly from the central axis. The support elements differ in the presence or axial positions of stabilising pads (250) thereon such that at least one support element differs from at least one other support element in the presence or axial position of at least one stabilising pad. This arrangement allows the stabilising pads to be positioned at or close to full gauge, thereby reducing vibration.

A concentric alignment device is provided that elevates the working face of a drill bit off of the inner wall of a casing or tubing to prevent premature wear of the working face of the drill bit. In horizontal drilling applications, the working face of a drill bit has a tendency to contact or rest on the inner wall of a casing or tubing, which negatively affects the working face of a drill bit. In some embodiments, one or more optional inserts are provided on the shank of a drill bit or on a centralizing sub such that the inserts contact the inner wall of a casing or tubing instead of the working face of the drill bit. In other embodiments, blade packages on a drill bit or sub contact the inner wall of a casing or tubing and also pump drilling fluid in a downhole direction.

A cutting table for use in subterranean formations comprises a base structure of hard material and at least one ridge structure of hard material. The base structure comprises a side surface, an upper surface, and a cutting edge between the upper surface and the side surface. The at least one ridge structure vertically extends from the base structure and is positioned horizontally inward of the cutting edge. A cutting element for use in subterranean formations and an earth-boring tool are also described.

Earth-boring tools include a body, at least one first blade extending outward from the body, and at least one second blade extending outward from the body. The at least one first blade includes an upper surface, a first gage region having a first longitudinal length, and a recess extending at least partially into the at least one first blade from the upper surface. The at least one second blade includes a second gage region having a second, greater longitudinal length. Additional earth-boring tools include first blades having first gage regions of a first longitudinal length and second blades having second gage regions of a second, greater longitudinal length. An upper external surface is tapered radially outward in a longitudinally upward direction relative to a central axis of the earth-boring tool. Methods including forming such first and second blades and removing material from the first blades to form recesses.

A drill bit comprises a bit body having a longitudinal axis and a blade extending radially outward from the longitudinal axis along a face region and axially along a gauge region. A gauge region includes a gauge feature and first and second recessed regions extending axially above and below the gauge feature, respectively. The gauge feature comprises an outermost surface extending radially beyond outer surfaces of the blade in the recessed regions. A method of drilling a borehole comprises rotating the bit about the longitudinal axis, engaging a formation with cutting elements mounted to the face region, and increasing a lateral force applied substantially perpendicular to the longitudinal axis such that radially outer surfaces in the gauge region engage the formation and such that side cutting exhibited by the bit is initially minimal and substantially constant and subsequently increases in a substantially linear manner with increasing lateral force.

A drilling machine for a wellbore is provided. The drilling machine may include a dynamic lateral pad that is movable between an extended and retracted position. In the extended position, the pad moves the drill bit in a direction for drilling. The drilling machine may include a dynamic lateral cutter that is movable between an extended and retracted position. In at least the extended position, the cutter engages the wellbore and removes formation. The drilling machine may include a monolithic or integral drill bit/drive shaft to reduce the distance between a positive displacement motor and a distal end of the monolithic or integral drill bit/drive shaft. The drilling machine may include separate cutting structures that have different rotational speeds and can further utilize the integral drill bit/drift shaft and/or a bent housing that generates an off-axis rotation which helps optimize the formation removal in the center area of the wellbore.

An earth-boring tool for drilling a subterranean formation includes a bit body having a central axis and a cavity extending into the bit body from an outer surface thereof. A bearing element assembly may be mounted within the cavity. The bearing element assembly comprises a lower retaining member, an upper retaining member mounted over to the lower retaining member, the upper retaining member comprising an aperture formed therethrough, and a spherical bearing element disposed over the lower retaining member and extending through the aperture formed through the upper retaining member. The spherical bearing element is rotatable about three axes of rotation within the lower retaining member and the upper retaining member.