Force coupling or torque coupling assemblies, apparatuses, systems, and methods include assemblies that each include superhard contact elements. At least some of the superhard contact elements may be configured to remain in contact with each other when a rotational force and/or a thrust force is applied between the assemblies.

A lubricating system is disclosed. The lubricating system includes: at least one first to-be-lubricated component, wherein an inlet of each of the at least one first to-be-lubricated component is connected with a first lubrication oil inlet pipe, and an outlet of the each of the at least one first to-be-lubricated component is connected with a first lubrication oil outlet pipe; and at least one second to-be-lubricated component, wherein an inlet of each of the second to-be-lubricated component is connected with a second lubrication oil inlet pipe, and an outlet of the each of the at least one second to-be-lubricated component is connected with a second lubrication oil outlet pipe. An operating pressure of the each of the at least one first to-be-lubricated component is different from a working pressure of the each of the at least one second to-be-lubricated component.

A downhole-type device includes an electric machine. The electric machine includes an electrical rotor configured to couple with a device to drive or be driven by the electric machine. An electrical stator surrounds the electric rotor. The electric stator includes a seal configured to isolate stator windings from an outside, downhole environment. An inner surface of the seal and an outer surface of the electric rotor define an annulus exposed to the outside environment. A bearing couples the electric rotor to the electric stator. A lubrication system is fluidically coupled to the downhole-type device. The lubrication system includes a topside pressure pump and a downhole-type distribution manifold configured to be used within a wellbore. The distribution manifold is fluidically connected to the topside pressure pump and the bearing to receive a flow of lubricant from the topside pressure pump.

A rotary steerable drilling tool and a method according to which a universal joint is sealed. In one embodiment, the method includes providing the collar, the shaft, the universal joint, and first and second shoulders between which the universal joint is positioned; providing first and second self-energizing seals between the collar and the shaft on opposite sides of the universal joint; rotating the collar and the shaft; seating the first self-energizing seal against the first shoulder; and seating a second self-energizing seal against the second shoulder. In one embodiment, the universal joint includes a convex surface formed on the shaft; a first concave surface extending circumferentially about the shaft and adapted to mate with the convex surface to carry a first axial load; and a spacer ring defining a second concave surface adapted to mate with the convex surface to carry a second axial load.

A speed-enhancing drilling tool includes an upstream drill string (10), which has a drive motor and a first driving rod coupled therewith, a downstream drilling bit; and a percussive device connected between the upstream drilling string and the downstream drilling bit. The first driving rod extending axially and the drive motor are configured to drive the first driving rod in rotation. The percussive device has a rotary driving part having an upper end engaged with the first driving rod to rotate together therewith; and a rotary working part having an upper end engaged with a lower end of the rotary driving part and a lower end connected with the downstream drilling bit. The rotary working part can be driven by the rotary driving part to rotate about its axis, and axially movable relative thereto; and a percussion generating part arranged around the rotary working part.

A high-power turbine fracturing system may include a lubrication system, which may include a first lubrication unit configured to lubricate a plunger pump. The first lubrication unit may further include a high-pressure lubrication unit. The high-pressure lubrication unit may include a high-pressure motor, a high-pressure pump, and a high-pressure oil line. The high-pressure motor may be configured to drive the high-pressure pump, which may be configured to pump high-pressure lubricating oil into the high-pressure oil line. The high-pressure oil line may be configured to lubricate at least one of connecting rod bearing bushes or crosshead bearing bushes in the plunger pump.

A thrust bearing is described comprising first and second bearing assemblies (15, 17) rotatable relative to each and a plurality of axially arranged bearing stages (14a, 14b) formed between the first and second bearing assemblies (15, 17). Each bearing stage comprises a first load shoulder (16) provided on the first bearing assembly (15), a second load shoulder (18) provided on the second bearing assembly (17), a bearing structure (30) defined between the first and second load shoulders; and an extrudable component (32) forming part of the bearing structure. Wherein axial load applied between the first and second bearing assemblies (15, 17) in a first relative axial direction is transmitted between respective pairs of first and second load shoulders via the extrudable components (32) of respective bearing structures (30). The extrudable components (30) provide for load balancing between each bearing stage (14a, 14b).

A drilling system for drilling a borehole. The drilling system may include a drill string, a drill bit coupled to the drill string, a mud motor coupled to the drill string uphole of the drill bit and operable to rotate the drill bit via a driveshaft, a bearing assembly coupled to a downhole end of the mud motor and operable to support the driveshaft, and a rotary steerable system (“RSS”) operable to push the drill bit in a desired direction via pads extended using drilling fluid flowing through the driveshaft and to the RSS. The bearing assembly may include bearings positioned circumferentially around a bore of the bearing assembly, a fluid flowpath through the bearings to allow drilling fluid to pass through the bearings, and a choke assembly positioned in the fluid flowpath and operable to restrict a flow of the drilling fluid through the fluid flowpath.

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.

An apparatus for damping vibrations includes an inertial mass disposed in a cavity in a rotatable downhole component, the rotatable component configured to be disposed in a borehole in a subsurface formation, such as a resource bearing formation, the inertial mass coupled to a surface of the cavity by a damping fluid and configured to move within the cavity relative to the downhole component. The apparatus also includes a damping fluid disposed in the cavity between the inertial mass and an inner surface of the cavity, where rotational acceleration of the rotatable downhole component causes shear in the damping fluid to dissipate energy from rotational acceleration of the rotatable downhole component and causing the rotational acceleration to be reduced.