Abstract: A drilling system can be used 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Anti-rotation pad assemblies are provided for restraining rotation of a non-rotating housing in geologic drilling system. The anti-rotation pad assemblies include extensible members, which extend from an internal cavity in the anti-rotation pad assemblies and are capable of engaging a wellbore wall. The extensible members may include rollers that are biased radially outwardly to engage the wellbore wall such that the anti-rotation pad assemblies may move axially within the wellbore while restraining the non-rotating housing in a particular rotational orientation. Flow ports are defined in the anti-rotation pad assemblies to encourage mud flow through the internal cavity, and thereby discourage the accumulation and solidification of drilling fluids around the extensible members. The extensible members thus remain free to move under the bias of a biasing mechanism within the internal cavity and can thus effectively maintain the rotational orientation of the non-rotating housing in the wellbore.

Abstract: Anti-rotation pad assemblies are provided for restraining rotation of a non-rotating housing in geologic drilling system. The anti-rotation pad assemblies include extensible members, which extend from an internal cavity in the anti-rotation pad assemblies and are capable of engaging a wellbore wall. The extensible members may include rollers that are biased radially outwardly to engage the wellbore wall such that the anti-rotation pad assemblies may move axially within the wellbore while restraining the non-rotating housing in a particular rotational orientation. Flow ports are defined in the anti-rotation pad assemblies to encourage mud flow through the internal cavity, and thereby discourage the accumulation and solidification of drilling fluids around the extensible members. The extensible members thus remain free to move under the bias of a biasing mechanism within the internal cavity and can thus effectively maintain the rotational orientation of the non-rotating housing in the wellbore.