A universal joint assembled in a drill string transfers torque between two shafts where the shafts are not completely aligned. The universal joint includes a cable that passes through joint components. The cable limits separation or deflection of the joint components.

An improved sealed bearing pack for a downhole mud motor is disclosed. More specifically, embodiments of the present invention relate to a mud motor for straight and directional drilling with a sealed bearing pack designed to withstand higher torques, loads, and pressure operations and with a reduced failure rate. In some embodiments, the sealed bearing pack has more lateral support for improved horizontal drilling and extended operational life. Thus, one embodiment includes an adapter housing extending the length of the outer housing and a bearing within the adapter housing for increased support. Additionally, some embodiments include two thrust bearing assemblies for improved operations and reduced failures. Various embodiments include a longer flow sleeve than prior art sealed bearing packs.

A jet flow adjustment method for rotary steerable downhole release relates to a technical field of downhole drilling equipment for oil wells, which includes steps of: defining a diversion ratio p of a jet nozzle (2) by a ground control system according to a cleaning requirement of a cuttings bed; and sending the diversion ratio p of the jet nozzle (2) to a control unit of a downhole rotary steerable system; and determining an opening area s of the jet nozzle (2) by the control unit of the downhole rotary steerable system according to the diversion ratio p of the jet nozzle (2) and an equivalent channel area S of a drilling tool, wherein a calculation formula is: s=p*S/(1−p); controlling an adjustable bypass valve (3) by the control unit of the downhole rotary steerable system according to the calculated opening area s of the jet nozzle (2), so as to control an overlapping area between sector holes (9) of a rotor end (7) and a stator end (8), thereby opening the jet nozzle (2) for release. The present invention has simple control and strong release ability, which can effectively solve the jamming problem of the rotary steerable downhole tool.

A disclosed mud motor includes a rotor head, a motor block, a hollow rotor, an inlet shaft, and an outlet shaft. In the operation of one embodiment, a pressurized drilling mud enters the rotor head through the inlet shaft. Some or all of the drilling mud is directed through an included inlet passage onto pistons which are included in the motor block and disposed concentrically around the outlet shaft. A downward action of the pistons resulting from the drilling mud causes an included power plate to rotate. Rotation of the power plate causes the hollow rotor and the rotor head to also rotate. The hollow rotor may be attached to a drilling implement. Rotation of the power plate also causes some or all of the drilling mud directed onto the pistons to be discharged into the outlet shaft through an included discharge passage. During the operation of one embodiment of the mud motor, the pistons do not rotate around the outlet shaft, but instead remain substantially in their original concentric alignment.

Methods and apparatuses for controlling a trajectory of a borehole being drilled into the earth are provided. The apparatus includes a drilling system including a drill tubular, a disintegrating device, and a steering system coupled to the drill tubular configured to steer the drilling system, the drilling system configured to drill the borehole by receiving control outputs from at least one control unit for controlling parameters of the drilling system, the at least one control unit configured to provide the control outputs to the steering system, the at least one control unit being configured to provide depth-based control.

This invention relates to an apparatus and method for controlling a part of a downhole assembly, and to the downhole assembly. The downhole assembly may include a steering mechanism adapted to steer a drill bit in a chosen direction, and the steering mechanism may be the part of the downhole assembly which is controlled by the apparatus. The downhole assembly includes a drill bit and a motor, the motor having a stator and a rotor, the rotor being driven to rotate relative to the stator by the passage of a drilling fluid along a drilling fluid path between the rotor and the stator. The motor has a conduit through which the drilling fluid can pass, the conduit being separate from the drilling fluid path, and the apparatus has a valve to control the flow of drilling fluid through the conduit. The invention provides a robust and reliable means of delivering high pressure drilling fluid downstream of the motor.

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 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.

An apparatus for drilling curved and straight sections of a wellbore is disclosed that in one non-limiting embodiment includes a drilling assembly configured to include a drill bit at an end thereof that can be rotated by a drive in the drilling assembly and by the rotation of the drilling assembly, and wherein the drilling assembly includes: a deflection device that (i) tilts a section of the drilling assembly within a selected plane when the drilling assembly is substantially rotationally stationary to allow drilling of a curved section of the wellbore by rotating the drill bit by the drive; and (ii) straightens the section of the drilling assembly when the drilling assembly is rotated to allow drilling of a straight section of the wellbore.

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.