A damping device for use with a downhole tool having a tool axis and an expected operational temperature range, may comprise a device housing mechanically coupled to the tool and including a volume; and an inertia element movably supported in the receptacle and having a volume, a mass, and a non-zero moment of inertia about the tool axis. The inertia element may be supported within the receptacle such that the inertia element can move relative to the device housing and an interface between the device housing and the tool may include an area-altering feature. The device housing has a coefficient of thermal expansion that allows the interface to transmit a predetermined amount of torque and a predetermined amount heat across at expected operational temperatures. The interface may include a thermally conductive material in thermal contact with the device housing and the tool.

There is disclosed a torque transfer apparatus for a mineral drilling tool used in a downhole assembly of a drill string. The drilling tool has a downhole drill bit and one or more uphole drill bits spaced apart from the downhole drill bit, with the torque transfer apparatus being located between them. The apparatus has an axial bore therethrough for fluid flow and comprises first and second members being rotatably joined to each other. The apparatus rotationally couples and transfers torque between the first and second members when a torque difference between torque on the downhole drill bit and torque on the uphole drill bit is below a threshold torque value. The apparatus disengages the rotational coupling while the torque difference exceeds the threshold torque value. The flow rate of drilling fluid flowing through the axial bore is altered when the apparatus engages and disengages the coupling.

The present disclosure relates to coupler for connecting a drill pipe to a drill bit as well as methods for manufacturing the same. In particular, the present disclosure describes a coupler which includes a housing including a first connecting portion at a first end for connecting to a drill pipe, a base coupled to the housing and including a second connecting portion at a second end for connecting to a drill bit, and an intermediate component disposed between the base and the housing, wherein the coupler is configured for rotation about an axis during use, with the intermediate component allowing limited relative rotation between the housing and the base about the axis.

A damping device for use with a downhole tool having a tool axis and an expected operational temperature range, may comprise a device housing mechanically coupled to the tool and including a volume; and an inertia element movably supported in the receptacle and having a volume, a mass, and a non-zero moment of inertia about the tool axis. The inertia element may be supported within the receptacle such that the inertia element can move relative to the device housing and an interface between the device housing and the tool may include an area-altering feature. The device housing has a coefficient of thermal expansion that allows the interface to transmit a predetermined amount of torque and a predetermined amount heat across at expected operational temperatures. The interface may include a thermally conductive material in thermal contact with the device housing and the tool.

A drive sub for a drilling assembly includes a tubular body configured to receive and releasably engage a drilling tool. The body has inner and outer faces and further has a castellated edge provided on its operative downhole end, which edge defines a plurality of lugs separated from each other by intervening slots. In one aspect the drive sub has a contour profile provided at least in partially along a circumference of the castellated edge, wherein the contour profile traverses the castellated edge substantially from the inner face to the outer face. In another aspect the drive sub has a channel provided in each of the lugs, wherein the channel at least partially traverses the lugs and leads from an inlet opening on the castellated edge to an outlet opening on the outer face. The contour profile and/or channel facilitate flow of drilling fluid and cuttings past the lugs during use.

A shock absorber apparatus includes a rod; a tool connection on a first end of the rod; a piston on a second end of the rod; a flange on the rod between the tool connection and the piston; a ring connection slidably connected to the rod between the tool connection and the flange; a first spring between the ring connection and the flange to bias the ring connection axially away from the flange; a sleeve, connected to a second spring between the second spring and the piston, slidably encircling the piston and a portion of the rod, and extending past the piston to a pumpdown connection; and a fin. A method for a placing a tool in a landing ring of a drilling tubular includes using the shock absorber apparatus to absorb shocks caused by the landing operation.

A vibration damping device for use with a downhole tool having a tool axis and a drill string component (DSC), may comprise an inertia ring rotatably mounted on the DSC and including at least one cutout defining a chamber therein such that the DSC forms an end wall of the chamber, and a leaf spring disposed in the chamber, the leaf spring having first and second spring ends, the first end being attached to the inertia ring or the DSC such that relative rotation between the inertia ring and the DSC distorts the leaf spring. The second spring end may engage the other of the inertia ring or the DSC. A fluid may be included in the chamber and the spring may divide the chamber into two portions, so that relative rotation between the inertia ring and the DSC distorts the leaf spring and varies the volumes of the portions.

A ball transfer mechanism for a harmonic drive and linear piston motor is disclosed. The ball transfer mechanism includes a spherical ball and a cylindrical seat portion. The seat portion defines a hemispherical shaped recess with a contour for receiving the ball. The ball transfer mechanism is in an exterior wall of a housing for converting rotary motion to linear motion, driving a linear piston motor. The harmonic drive drives a rotor of the linear piston motor. The harmonic drive includes a hollow cylindrical coupler portion engaging a rotor portion for transferring torque to the rotor portion. Transfer mechanisms disposed along a housing wall of the linear piston motor engage the coupler portion. The coupler portion includes harmonic cam grooves for receiving spherical balls in the ball transfer mechanism that drives rotational motion in the rotor in response to axially linear movement of the piston assembly.

A vibration isolating coupler including a first coupler portion, a second coupler portion including an external surface and an internal surface portion, and a vibration isolating portion extending between the first coupler portion and the second coupler portion. The vibration isolating portion including a first solid annular portion and a second solid annular portion. The vibration isolating portion including a plurality of slots extending from the first solid annular portion toward the second solid annular portion forming a plurality of vibration isolating elements. Each of the plurality of vibration isolating elements is disconnected from adjacent ones of the plurality of vibration isolating elements by a corresponding one of the plurality of slots. The plurality of vibration isolating elements enabling torsional rotation of the first coupler portion relative to the second coupler portion.

Systems and methods for damping torsional oscillations of downhole systems are described. The systems include a downhole drilling system disposed at an end of the downhole system in operative connection with a drill bit. A damping system is installed on the downhole drilling system, the damping system having at least one damper element configured to dampen at least one HFTO mode. At least one mode-shape tuning element is arranged on the drilling system. The at least one mode-shape tuning element is configured and positioned on the drilling system to modify at least one of a shape of the HFTO mode, a frequency of the HFTO mode, an excitability of the HFTO mode, and a damping efficiency of the at least one damper element.