The compensating device has a through passage that goes to the borehole tool. There is a lateral passage to a piston housing. Through the use of a differential piston area on the outer housing, a net uphole force results from backpressure as a result of flow pumped through a section mill that mills in an uphole direction. If the vessel goes down the mill is just pushed away from the tubular being cut. If wave action takes the vessel up fluid is displaced back into the mandrel but the constant force up that is dependent on the existing backpressure in the tubing keeps a steady uphole force on the mill. The tool can be reversed for applications that require a net down force during milling. Rotational locking between the mandrel and the outer housing can be used. Ports are sized to prevent damping responses.

Methods and systems for damping torsional oscillations of downhole systems are described. The systems include a downhole string, a bit support assembly configured to support and receive a disintegration device, wherein the disintegration device is disposed on an end of the downhole string and mounted to the bit support assembly, and a damping system configured at least one of on and in the bit support assembly, the damping system comprising at least one damper element arranged in contact with a portion of the bit support assembly.

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 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.

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.

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 petroleum drill-string shock absorber includes a drill collar nipple, a driving unit, an outer shell, a helical guideway, a drill bit base, a woven metal ring and a vibration-absorbing composite beam, the vibration-absorbing composite beam consists of a sheet metal and a flexible material gasket bonded by an adhesive; the drill collar nipple is connected with the helical guideway; the helical guideway is connected with the drill bit base; the driving unit rotates on the helical guideway; the outer shell is connected with the drill bit base; a metal seal ring is configured to seal a space formed between the outer shell and the drill collar nipple, a sealed space is formed among the drill collar nipple, the outer shell and the drill bit base; the woven metal ring is placed between the helical guideway and the drill bit base configured to absorb an axial impact vibration.

The invention relates to a composite shock absorber for a polycrystalline diamond compact bit, comprising a drilling tool body having a water inlet, an impact body having a water outlet and forming a shock absorption cavity, a disc spring group having an annular pressing sleeve, a cylindrical torsion bar spring which has an external thread and a spline, is connected to the drilling tool body through threads and extended into an impactor and connected thereto through the spline, and the annular pressing sleeve, wherein bit vibration impact force is transmitted therebetween through a torsion transmission joint, and a bearing group is arranged between the lower end surface of the annular pressing sleeve and an annular step of the impact body. The composite shock absorber can weaken damage of the slippage effect to polycrystalline diamond compact cutting teeth, absorb axial vibration from a drill stem and prolong the service life of the bit.

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.