A downhole device delivery and drive transfer system includes a sub which is arranged to attach to a drill string and a tool which is configured to enable it to travel through the drill string and releasably couple to the sub. The sub and the tool are arranged so that when they are releasably coupled to each other torque imparted to the drill string is transferred by the sub to the tool. The tool is arranged to carry one or more devices for performing one or more downhole functions such as core drilling, hole reaming or wedge placement for directional drilling. The system also has a guide mechanism that operates between the sub and the tool to guide the tool to a known rotational orientation relative to the sub as the tool travels into the sub. A fluid control system controls the flow of fluid through the tool through a downhole outlet and a plurality of ports intermediate opposite ends of the tool.

A method of performing an intervention operation at a multilateral well includes deploying a directional guide to an axial position within the multilateral well at which a lateral section of the multilateral well is located. The method further includes installing a main body of the directional guide to an inner surface profile arranged along a casing that surrounds the directional guide at the axial position. The method further includes closing a bore that passes through the main body along an elongate axis of the main body. The method further includes deflecting an intervention assembly along a guide surface of the main body into the lateral section. The method further includes controlling the intervention assembly to perform the intervention operation within the lateral section.

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.

Provided, in one aspect, is a well system and a method for forming a well system. The well system, in one aspect, includes a main wellbore, the main wellbore having a main wellbore open hole section, and a lateral wellbore extending from the main wellbore, the lateral wellbore having a lateral wellbore open hole section. The well system, according to this aspect, further includes a main bore completion located within the main wellbore and a lateral bore completion located within the lateral wellbore, and a multilateral junction positioned at an intersection between the main wellbore open hole section of the main wellbore and the lateral wellbore open hole section of the lateral wellbore, the multilateral junction including a main bore leg forming a first pressure tight seal with the main bore completion and a lateral bore leg forming a second pressure tight seal with the lateral bore completion such that the main bore completion and the lateral bore completion are hydraulically isolated from one another.

A method of performing an intervention operation at a multilateral well includes deploying a directional guide to an axial position within the multilateral well at which a lateral section of the multilateral well is located, installing a main body of the directional guide to an inner surface profile arranged along a casing that surrounds the directional guide at the axial position, closing a bore that passes through the main body along an elongate axis of the main body, deflecting an intervention assembly along a guide surface of the main body into the lateral section, and controlling the intervention assembly to perform the intervention operation within the lateral section.

A bottom hole assembly (BHA) includes a whipstock having a latch release mechanism and a milling tool having a plurality of blades and a lock mechanism. The BHA also includes a collar coupled to the whipstock and disposed about a portion of the milling tool, wherein the blades of the milling tool abut the collar. The milling tool is releasably coupled to the whipstock by the interaction of the latch release mechanism and the lock mechanism.

Provided is a multilateral junction, a well system, and a method. The multilateral junction, in at least one aspect, includes a mainbore leg having a first mainbore leg end and a second opposing mainbore leg end, as well as a lateral bore leg having a first lateral bore leg end and a second opposing lateral bore leg end. The multilateral junction, according to this aspect, further includes a lateral locating assembly coupled to the second opposing lateral bore leg end, the lateral locating assembly including: a tubular; and a bendable deflection tip coupled to the tubular, the bendable deflection tip configured to move between a straight position and a bent position upon the application of fluid pressure thereto.

A method of performing a well bore operation in a well bore includes connecting a window mill to a whipstock connector forming a tubular section, supporting a tool below the whipstock connector, running the window mill, the whipstock connector, and the tool into the well bore, and axially loading the tool to perform the well bore operation.

Provided is a mill bit and well system. The mill bit, in one aspect, includes a tubular having an uphole end and a downhole end. The mill bit, in accordance with this aspect, further includes a first cutting section having one or more first cutting surfaces disposed about the tubular, the first cutting section having a first material removal rate and configured to engage with wellbore casing disposed within a wellbore. The mill bit, in accordance with this disclosure, further includes a second cutting section having one or more second cutting surfaces disposed about the tubular, the second cutting section having a second material removal rate less than the first material removal rate and configured to engage with a whipstock disposed within the wellbore.

A mill including a housing having a fluid bypass pathway, a milling feature at a longitudinal end of the housing, a chamber defined by the housing, and a piston disposed in communication with the chamber, the piston defining a fluid passageway initially aligned with the fluid bypass pathway, the piston responsive to pump pressure to move toward the milling feature, the movement misaligning the fluid passageway with the fluid bypass pathway.