Certain aspects and features relate to a drilling system usable to drill a borehole. The drilling system may include a first housing defining a main fluid flow path and a second housing defining a bypass flow path toward an annulus of a wellbore. A flow control choke may be positioned between the first housing and the second housing. The flow control choke may include a rotatable section and a stationary section that is stationary relative to the rotatable section. The stationary section may have a curved interface with the rotatable section for restricting a flow of a drilling fluid through the bypass flow path.

A communication system can include a first subsystem of a well tool that can include a first cylindrically shaped band positioned around the first subsystem. The first cylindrically shaped band can be operable to electromagnetically couple with a second cylindrically shaped band. The communication system can also include a second subsystem of the well tool. The second subsystem can include the second cylindrically shaped band positioned around the second subsystem. The communication system can further include an intermediate subsystem positioned between the first subsystem and the second subsystem. The intermediate subsystem can include an insulator positioned coaxially around the intermediate subsystem.

A sealing unit (115) for sealing an annular gap (109) formed between a seal wear ring (106) and a seal carrier (112) has a sealing ring holder (118) which is U-shaped in a receptacle region and which, together with the receptacle region, encloses a fixing region (209) of the sealing ring (121).

A downhole drilling motor, system, and method for using same are disclosed. A downhole drilling motor can include a power section stator having a first end, a second end, an internal cavity passing therethrough. The downhole drilling motor can further include a rotor assembly positioned and fully encased in the internal cavity. The rotor assembly includes a power section rotor, a drivetrain operably coupled to the power section rotor and a bearing set. The power section rotor is positioned at the first end within the internal cavity of the power section stator. The power section rotor, the drivetrain, and the bearing set are fully encased in the internal cavity of the power section stator. Additional apparatuses, systems, and methods are disclosed.

A downhole motor for directional drilling includes a driveshaft assembly including a driveshaft housing and a driveshaft rotatably disposed within the driveshaft housing, a bearing assembly including a bearing housing and a bearing mandrel rotatably disposed within the bearing housing, wherein the bearing mandrel is configured to couple with a drill bit, a bend adjustment assembly including a first position that provides a first deflection angle between a longitudinal axis of the driveshaft housing and a longitudinal axis of the bearing mandrel, and a second position that provides a second deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel that is different from the first deflection angle, and one or more hydraulic pumps configured to actuate the bend adjustment assembly between the first position and the second position.

A universal joint assembled in a drill string transfers torque between two components where rotation of the components may not be completely aligned. The universal joint includes upper and lower members with radial teeth connected by a serpentine retainer. As the joint rotates the members can pivot within the confines of the serpentine retainer to accommodate misalignment of the components. Axial force can be transferred through a bearing member between the members.

A method for actuation of a downhole device includes rotating a drill pipe relative to a cylindrical pipe disposed coaxially within the drill pipe. First segments including a first material are disposed on the inner surface of the drill pipe. Second segments including a degradable material are disposed on the outer surface of the cylindrical pipe, with each of the second segments aligned with a corresponding first segment. The first material and the degradable material are insoluble in the downhole fluid, and a solubility of the degradable material in a solvent is greater than a solubility of the first material in the solvent. The method includes generating a first electrical signal pattern during rotation of the drill pipe; introducing the solvent into the drill pipe, in which the degradable material degrades responsive to introduction of the solvent; and generating a second electrical signal pattern after introduction of the solvent.

A drilling system for drilling a wellbore using drilling fluid includes a drillstring, a drill bit coupled to the drillstring, and a mud motor coupled to the drillstring and operable to rotate the drill bit by rotating a driveshaft with a bore. The drilling system also includes a bearing assembly that includes a bypass fluid flowpath through the bearings for drilling fluid to divert from the bore. A choke assembly positioned in the bypass fluid flowpath restricts flow of the diverted drilling fluid such that some diverted drilling fluid flows into an annulus in the wellbore outside of the bearing assembly through an unsealed annulus port and some of diverted drilling fluid is recaptured through a return flowline. The drilling system also includes a rotary steerable system operable to push the drill bit in a desired direction using pads extendable with the drilling fluid.

A bearing element for a bearing assembly has a body of polycrystalline diamond (PCD) material having a bearing contact surface, and a substrate bonded to the body of PCD material along an interface and having a free end surface. The substrate has a through-bore extending longitudinally therethrough, the body of PCD material having a portion extending through the through-bore in the substrate to at least the free end surface thereof, the substrate extending around the peripheral side edge of the portion of PCD material extending therethrough.

Methods for manufacturing bearings and wear resistant surfaces usable in various downhole tools are described herein. A housing is provided. A laser configured for insertion into the housing, such as an inner diameter laser, is used to connect a fusible material to the inner surface of the housing or an insert disposed therein to form a hard facing layer on the inner surface. Simultaneously or independently, the laser can be used to connect the fusible material to the outer surface of a mandrel within the housing to form a second hard facing layer. The present methods thereby produce durable radial bearings having extended operational life, which can be produced within a bearing housing, or externally for transport and installation in existing bearing housings.