A reverse-circulation drilling assembly having an overshot subassembly and a head subassembly. In the event retrieval of the drilling assembly by reverse-circulation fails, the drilling assembly can be retrieved using a secondary overshot.

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 cutting tool with a cutting region and a connecting support region where the support region is designed to connect to an external motor assembly. The cutting tool is also has a porous region that is integrated within a portion of the tool such that as the tool cuts material the porous region can allow samples of the cut material to permeate into an internal chamber of the tool. Once in the internal chamber material samples can be analyzed in-situ for direct composition analysis.

Fluid control assemblies including at least one ring. The fluid control assemblies are used within core barrel assemblies to: provide an indication that a core barrel assembly has reached a drilling position and is latched to a drill string; serve as a mechanical shut-off valve that restricts the flow of drilling fluid within a core barrel assembly; and/or serve as a grease seal at the connection between an inner tube cap and an inner tube that receives a core sample.

A drill rod for assembly with other drill rods to form a drillstring used for fluid reverse circulation drilling comprising: an outer drill rod comprising a lightweight drill rod used in core drilling with a bore, an inner drill rod comprising a bore, a first coupling member removably coupled to one end of the inner drill rod, a second coupling member removably coupled to a second end of the inner drill rod, wherein the first and second coupling members centre the inner drill rod within the outer drill rod.

A drill rod for assembly with other drill rods to form a drillstring used for fluid reverse circulation drilling comprising: an outer drill rod comprising a lightweight drill rod used in core drilling with a bore, an inner drill rod comprising a bore, a first coupling member removably coupled to one end of the inner drill rod, a second coupling member removably coupled to a second end of the inner drill rod, wherein the first and second coupling members centre the inner drill rod within the outer drill rod.

[Problem] To provide: a core barrel head capable of definitely recovering an inner tube in which a geological sample has been collected in a situation where excavation is performed in a horizontal direction and in a rising gradient direction; an inner tube assembly provided with said core barrel head; and an inner tube recovery method.

[Solution] The present invention has: a main shaft 31 connected to the rear end of an inner tube 2; an inner fixing latch 32 that is axially supported at a substantially intermediate position along an axial direction of the main shaft 31; a latch disengagement slide tube 33 that is mounted to the outer circumferential surface of the main shaft 31 slidably in the axial direction and that disengages the inner fixing latch 32 from a locking groove 43 by inclining the inner fixing latch 32 against a biasing force; and a slide tube fixing latch 34 that locks the latch disengagement slide tube 33 at a position where the inner fixing latch 31 is in an expansion state and that disengages the lock of the latch disengagement slide tube 33 by being inclined by an overshot.

[Problem] To provide: a core barrel head capable of definitely recovering an inner tube in which a geological sample has been collected in a situation where excavation is performed in a horizontal direction and in a rising gradient direction; an inner tube assembly provided with said core barrel head; and an inner tube recovery method.

[Solution] The present invention has: a main shaft 31 connected to the rear end of an inner tube 2; an inner fixing latch 32 that is axially supported at a substantially intermediate position along an axial direction of the main shaft 31; a latch disengagement slide tube 33 that is mounted to the outer circumferential surface of the main shaft 31 slidably in the axial direction and that disengages the inner fixing latch 32 from a locking groove 43 by inclining the inner fixing latch 32 against a biasing force; and a slide tube fixing latch 34 that locks the latch disengagement slide tube 33 at a position where the inner fixing latch 31 is in an expansion state and that disengages the lock of the latch disengagement slide tube 33 by being inclined by an overshot.

In one aspect the present invention may be said to comprise a drill rod for assembly with other drill rods to form a drillstring used for fluid reverse circulation drilling comprising: an outer drill rod comprising a bore that is tapered at each end, an inner drill rod within the outer drill rod, and a retention member removably coupled to each end of the inner drill rod to retain the inner drill rod between the tapered ends of the outer drill rod.