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 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 drill bit for a drill assembly including a friction bolt defining a longitudinal axial passage, the drill bit being adapted to be releasibly attached to the friction bolt and comprising: (i) a leading end including a cutting part; (ii) a following end; and (iii) an outer surface defining a friction bolt engaging means adapted to releasibly engage with the leading end of the friction bolt.

A drill bit for a drill assembly including a friction bolt defining a longitudinal axial passage, the drill bit being adapted to be releasibly attached to the friction bolt and comprising: (i) a leading end including a cutting part; (ii) a following end; and (iii) an outer surface defining a friction bolt engaging means adapted to releasibly engage with the leading end of the friction bolt.

A directional casing drilling system includes a casing string, a drilling rig and a retrievable Bottom Hole Assembly (BHA). The drilling rig includes a casing drive for rotating the casing string in the borehole, a control system for controlling the casing drive, and a mud pump for pumping a continuous flow of drilling mud into the casing string. The BHA includes a torque transfer section, with which it is secured in the casing string, and a drill bit section held in a drilling position in the torque transfer section. It further includes a mud drive that rotates the drilling position of the drill bit section about the longitudinal axis of the torque transfer section, and a communicating device for communicating the orientation of the drill bit to the control system. The BHA is steered by adjusting the rotational speed of the casing string.

A directional casing drilling system includes a casing string, a drilling rig and a retrievable Bottom Hole Assembly (BHA). The drilling rig includes a casing drive for rotating the casing string in the borehole, a control system for controlling the casing drive, and a mud pump for pumping a continuous flow of drilling mud into the casing string. The BHA includes a torque transfer section, with which it is secured in the casing string, and a drill bit section held in a drilling position in the torque transfer section. It further includes a mud drive that rotates the drilling position of the drill bit section about the longitudinal axis of the torque transfer section, and a communicating device for communicating the orientation of the drill bit to the control system. The BHA is steered by adjusting the rotational speed of the casing string.

The present invention relates to a downhole tool for removing a restriction in a well tubular metal structure having a wall and an inner diameter, the restriction partly blocking the inner diameter, creating an opening defined at least partly by a rim section of the restriction, the downhole tool having a tool axis and comprising a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge, wherein the second part of the downhole tool further comprises a locator for locating the rim section, a collecting means for collecting part of the restriction to be cut out by the cutting edge, the locator and the collecting means are rotating with the core bit until the locator locates the rim section and a threshold value is reached.

The present invention relates to a downhole tool for removing a restriction in a well tubular metal structure having a wall and an inner diameter, the restriction partly blocking the inner diameter, creating an opening defined at least partly by a rim section of the restriction, the downhole tool having a tool axis and comprising a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge, wherein the second part of the downhole tool further comprises a locator for locating the rim section, a collecting means for collecting part of the restriction to be cut out by the cutting edge, the locator and the collecting means are rotating with the core bit until the locator locates the rim section and a threshold value is reached.

A downhole tool, for removing a restriction in a well tubular metal structure having a wall and an inner diameter, has a tool axis and a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, and a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge. The second part of the downhole tool further includes a locator for locating the rim section, the locator being rotable with the core bit until the locator locates the rim section and a threshold value is reached.

A downhole tool, for removing a restriction in a well tubular metal structure having a wall and an inner diameter, has a tool axis and a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, and a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge. The second part of the downhole tool further includes a locator for locating the rim section, the locator being rotable with the core bit until the locator locates the rim section and a threshold value is reached.