The disclosure provides downhole tools with shaft regions that are hardened by a compressive residual stress created when an allotropic material in a precursor region transforms from a first allotrope to a second allotrope in response to heat, while continuing to occupy the same physical space. The disclosure further provides methods of forming such downhole tools.

The disclosure provides rotary drill bits with bit head regions or other downhole tools with regions in which an allotropic material in a precursor region has been transformed from a first allotrope to a second allotrope in response to a trigger. The disclosure further provides methods of forming such downhole tools and methods of triggering an allotropic phase transformation during their use.

A drilling assembly comprises a bit body having a central axis and a blade extending radially outward from the bit body. The blade is defined by a leading edge and a trailing edge. A gauge surface extends from the leading edge to a surface break and may be disposed at a gauge diameter from the central axis. A recessed surface extends from the surface break to the trailing edge. The recessed surface may be configured to avoid contact between the trailing edge and the wellbore wall.

A well drilling system can include a drilling tool with at least one component which is displaced by a material that changes shape. The material can be a shape memory material. The material may change shape in response to a temperature change. The component can be a drill bit cutter, a depth of cut control surface, a gauge surface or a stabilizer surface. A method of controlling a drilling operation can include configuring a drilling tool with a material which changes shape, and the material displacing at least one component of the drilling tool during the drilling operation. Displacement of the component can be controlled downhole to maintain drilling parameters (such as torque, vibration, steering performance, etc.) in desired ranges.

A drill bit for use in a wellbore is disclosed, including a bit body having a longitudinal axis; and at least one moveable member associated with a lateral extent of the bit body, wherein the at least one moveable member is configured to translate in a member axis that is substantially longitudinal. Further, a method of drilling a wellbore is disclosed, including providing a drill bit including a bit body having a longitudinal axis and at least one movable member associated with a lateral extent of the bit body; conveying a drill string into a formation, the drill string having the drill bit at the end thereof; drilling the wellbore using the drill string; and selectively translating at least one movable member in a member axis that is substantially longitudinal.

A downhole stabilizer (5), such as a drill motor stabilizer, comprises at least one reaming means and/or reinforcing means (10). The present invention also relates to an assembly (30), such as a downhole drilling assembly (31), comprising at least one such stabilizer (5) and/or a drill bit (40,41) comprising a gauge bit (42) at or near a drilling end (45) thereof, and a connection means (46) for connecting the drill bit (40,41) to a drill motor assembly (60), wherein the drill bit gauge (42) comprises a substantially cylindrical portion having a length less than or equal to approximately 1.0 times the nominal bit diameter. The present invention also relates to a novel locking mechanism (80), such as a lock and key mechanism, to allow locking of a shaft (70), e.g. a motor drive shaft (71), through or together with a stabilizer (5).

Earth-boring tools may include a body and a passively adjustable, aggressiveness-modifying member secured to the body. The passively adjustable, aggressiveness-modifying member may be movable between a first position in which the earth-boring tool exhibits a first aggressiveness and a second position in which the earth-boring tool exhibits a second, different aggressiveness responsive to forces acting on the passively adjustable, aggressiveness-modifying member.

A component of a drilling assembly comprises at least one blade having a gauge region comprising a bearing face for engaging a sidewall of a wellbore in a subterranean formation during rotation of the drilling assembly, and a rotationally leading edge rotationally preceding the bearing face and comprising an engagement profile comprising at least one of at least one chamfered surface and at least one radiused surface, the engagement profile different than another engagement profile of another rotationally leading edge of another region of the at least one blade. A drilling assembly, and a method for stabilizing a drilling assembly in a wellbore in a subterranean formation are also provided.

A drill bit and a method of drilling a wellbore utilizing the drill bit is disclosed. The method includes providing a drill bit including a bit body and at least one movable member associated with a lateral extent of the bit body. The method further includes conveying a drill string into a formation, the drill string having the drill bit at the end thereof and drilling the wellbore using the drill string. During drilling, the drill bit can selectively extend the at least one moveable member from the lateral extent of the bit body at a first rate and selectively retract the at least one moveable member to a retracted position at a second rate that is less than the first rate.

A polycrystalline diamond drill bit for percussion drilling, in small hole high silica ground. The bit is made having a bit body, and a series of inserts locating in the bit body, and the bits are made using a double chisel design, or a modified double chisel design. The inserts are either chiseled shaped inserts, or the inserts are a combination of chisel shaped inserts and conical inserts, and are set into the bit body at very specific angles, in order to attain slicing of the earth when percussion drilling is performed. The inserts have specific lengths to cut clearance for the bit body. The cutting angle and the radius of the tip of each insert in addition to the diameter of the inserts, provide for use of a machine thrust pressure and machine torque pressure at low ranges when the PCD bits are used in percussion drilling.