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.

The present invention relates to a drilling device. The device comprises at least one drill rod, the or each drill rod having a first cylindrical wall defining an elongate chamber for receiving a working fluid to form a fluid column, the length of the fluid column being equal to a total length of the elongate chambers of the or each drill rod. The device also comprises a displacement excitation device arranged at a proximal end of the fluid column and configured to excite the fluid column to cause the working fluid in the fluid column to oscillate, wherein the excitation device is configured to excite the fluid column at an excitation frequency at or within 10% of a natural frequency of the fluid column determined based on the fluid column having a fixed boundary condition at a proximal end thereof. The device further comprises a tool piston moveably mounted at a distal end of the fluid column and a drilling tool connected to the tool piston such that the oscillation of the working fluid in the fluid column imparts an oscillating force to the drilling tool.

A method of steering a drill bit while drilling a wellbore can include periodically delivering an impact to the drill bit as the drill bit is rotated by a drill string. The impact may be delivered to the drill bit when an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of the drill string. Another method of steering a drill bit while drilling a wellbore may include interconnecting a bend in a drill string between an impact tool and the drill bit, and periodically delivering an impact from the impact tool to the drill bit as the drill bit is rotated by the drill string. A directional drilling system can include a drill string having a bend interconnected therein, an impact tool, and a drill bit, the bend being interconnected in the drill string between the drill bit and the impact tool.

A method of steering a drill bit while drilling a wellbore can include periodically delivering an impact to the drill bit as the drill bit is rotated by a drill string. The impact may be delivered to the drill bit when an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of the drill string. Another method of steering a drill bit while drilling a wellbore may include interconnecting a bend in a drill string between an impact tool and the drill bit, and periodically delivering an impact from the impact tool to the drill bit as the drill bit is rotated by the drill string. A directional drilling system can include a drill string having a bend interconnected therein, an impact tool, and a drill bit, the bend being interconnected in the drill string between the drill bit and the impact tool.

A choke assembly for controlling air flow into a piston of a percussion tool for downhole drilling includes a choke and a choke adapter. The choke comprises a choke body and a choke opening in the choke body for fluid to flow therethrough. The choke further includes one or more arm slots formed into the choke body between an inner wall of the choke body and an outer wall of the choke body. The one or more arm slots are designed to receive one or more arms of a choke change tool. The choke adapter has an adapter opening extending through the choke adapter. The choke is sized to fit in the adapter opening. The choke is removable from the choke adapter after the choke is inserted into the adapter opening.

A choke assembly for controlling air flow into a piston of a percussion tool for downhole drilling includes a choke and a choke adapter. The choke comprises a choke body and a choke opening in the choke body for fluid to flow therethrough. The choke further includes one or more arm slots formed into the choke body between an inner wall of the choke body and an outer wall of the choke body. The one or more arm slots are designed to receive one or more arms of a choke change tool. The choke adapter has an adapter opening extending through the choke adapter. The choke is sized to fit in the adapter opening. The choke is removable from the choke adapter after the choke is inserted into the adapter opening.

This disclosure describes methods and systems for remote control of stroke length and frequency of percussion apparatus, such as a rock hammer drill. At a high level, the hammer drill is allowed to stay at a default low stroke length and high frequency to avoid applying excessive cyclic stress to the housing of the hammer drill and can be controlled to operate at a long stroke length and low frequency when the hammer drill has engaged the target material. The long stroke length and low frequency during operation can be initiated when a sufficient forward feed pressure is provided. While the hammer drill is idling or retracting, the forward fee pressure is not sufficient for the long stroke length operation and thus the drill operates at the default state and at a safe stress level to avoid premature damage.

A drill assembly for percussive drilling, includes a drill bit having a downhole portion and an attachment portion having a cylindrical male coupling thread, and a drill string element for transferring impacts from a percussion device to the drill bit and having a female coupling thread for threadedly coupling with the male coupling thread. The drill bit includes a first annular impact surface arranged on an uphole-side end the downhole portion, the first annular impact surface surrounding the attachment portion, and the drill string element includes, at a downhole-side end thereof, a second annular impact surface. The first and second impact surfaces are inclined with respect to a plane perpendicular to the longitudinal direction. A drill bit and drill string element are also disclosed.

A drill assembly for percussive drilling, includes a drill bit having a downhole portion and an attachment portion having a cylindrical male coupling thread, and a drill string element for transferring impacts from a percussion device to the drill bit and having a female coupling thread for threadedly coupling with the male coupling thread. The drill bit includes a first annular impact surface arranged on an uphole-side end the downhole portion, the first annular impact surface surrounding the attachment portion, and the drill string element includes, at a downhole-side end thereof, a second annular impact surface. The first and second impact surfaces are inclined with respect to a plane perpendicular to the longitudinal direction. A drill bit and drill string element are also disclosed.