A down-the-hole hammer drill bit retaining assembly is arranged to releasably retain a drill bit at a hammer arrangement of a percussion drilling apparatus. The retaining assembly includes a drive sub and a retainer ring. The drive sub has at least one indent to provide a fluid communication pathway for a flushing fluid extending over a radially outward facing surface of the retainer ring and into an internal region of the drive sub in contact with inwardly projecting splines.

A containment head comprises a center aperture, a reservoir, a wiping rubber, an outer body, a bottom plate and a support cylinder. The center aperture comprises a central portion of the containment head configured to pass around a tubing. The reservoir comprises a space within the outer body and above the bottom plate. The containment head is configured to selectively attach to a tubing cleaning assembly.

A downhole tool (30) particularly for controlling torque and torsion and also for absorbing/dampening vibration in a downhole string is provided and comprises an inner mandrel (1, 7, 11, 15) and an outer mandrel (14, 13, 12, 19) and a coupling mechanism (8) to couple the inner and the outer mandrel, the coupling mechanism comprising one or more longitudinally elongate members (8) acting between the inner and outer mandrel, wherein the one or more longitudinally elongate members are substantially fixed in their longitudinal length but substantially do not resist relative compressive longitudinal movement occurring between the inner and outer mandrels. The coupling mechanism is arranged such that compression of the inner and outer mandrels results in compression of the one or more longitudinally elongate members without necessarily resulting in relative rotation of the inner and outer mandrels.

A hammer drill assembly is arranged for coupling to a drill string, wherein the drill bit is releasably attached to a driver sub via a retaining sleeve. The retaining sleeve includes a body that extends between a ring at its forward end and a plurality of tips at its rearward end. Also, methods of attaching and detaching a drill bit from the rest of the assembly are provided.

An apparatus and method for alleviating spiraling in boreholes is disclosed. The apparatus includes a sub, which adjusts the length of the bottom-hole assembly in response to tension/compression, flexural bending and/or torque measurements made above and below the reamer so that the drill bit and the reamer cut at the same depth rate. The sub is connected between the drill bit and the reamer. The apparatus further includes measurement devices disposed on the bottom-hole assembly above and below the reamer, which are capable of measuring the tension/compression, flexural bending and torque in the bottom-hole assembly. The method includes use of a data processor, which determines which operational output signals to supply to the sub in order to adjust its length and thereby accomplish the desired drilling rates.

A down the hole hammer (10) incorporates: an inner tube assembly (100); a fluid flow control system (200); a bit retaining system (400); a porting sleeve (600); and a piston (700). Each of the: inner tube assembly (100); fluid flow control system (200); bit retaining system (400); porting sleeve (600); and piston (700) in their own right provide benefit to the overall operation and/or reliability of the hammer (10).

A length-adjustable connector for a downhole tool has an outer tubular body with an inner bore and a first locking profile accessible from the inner bore. A rotatable inner tubular body having a second locking profile is within the outer tubular body. The connector also has a threaded connection between the outer and- inner tubular bodies that causes axial movement of the inner tubular body relative to the outer tubular body as the inner tubular body rotates, and a locking sleeve having first and second ends sized to engage the first and second locking profiles respectively. The locking sleeve prevents relative rotation of the tubular bodies when engaged with the locking profiles. A connector is carried by the inner tubular body that extends axially away from the locking sleeve, and moves axially relative to the outer tubular body as the inner tubular body is rotated.

This invention relates to a torque control device for a downhole drilling assembly, the torque control device being adapted for connection to a drill bit. The torque control device includes an outer sleeve and an inner shaft, the outer sleeve being movable longitudinally relative to the inner shaft. The torque control device has a cylinder, a piston located within the cylinder, and a rotary valve to control the volume of the cylinder. The volume of the cylinder can be changed by way of the rotary valve whereby to adjust the weight on bit and thereby control the torque upon the drill bit.

Embodiments of a reciprocating tool, used to engage and clear obstructions in a wellbore, have a biasing spring located externally about an axially reciprocating and rotatable sleeve to act between the rotatable sleeve and the non-rotatable mandrel to bias the rotatable sleeve to an extended position. During a drill out operation, a non-rotatable sleeve, connected to the mandrel for telescoping over the mandrel and the rotatable sleeve during a downstroke of the mandrel, guides a drill string for drill-out of at least the mandrel and other internal components. Positioning the biasing spring external to the rotating sleeve and downhole of the non-rotating sleeve prevents engaging the spring with the drill string. The rotating sleeve provides an internal guide for the drill out string to further avoid engagement with the spring.

Vibration assisted rotary drilling (VARD) tools that provide axial compliance and low amplitude axial displacements at the drill bit while transmitting the full rotary speed and torque of the drill string to increase drilling penetration rate. The VARD tools consist essentially of: i) an axially compliant section which transfers axial load across the tool; ii) a mechanism for opposing ends of the tool to displace axially relative to each other; iii) an energy absorbing section which dampens axial bit displacements; iv) a rotation transfer section which allows any rotation and torque applied to the drill string above the tool to be applied to the bit; and v) an optional axial force generating section.