Patent ID: 8439131

Claim:
A drill bit assembly comprising: a bit body connectable to a tubular drill string, which bit body is provided with a longitudinal passageway therethrough for an operating tool to pass from an internal position in an attached drill string to an external position; a closure element for closing the passageway when the closure element is in a closing position, which closure element is externally removable from the passageway; and a passage tool attached to or connectable to the closure element in its closing position and disposed inside the bit body when the closure element is in a closing position, wherein the passage tool comprises: a lower part to which the closure element is attached or connectable, which lower part is arranged so that it can be moved out of the bit body together with the closure element, and an upper tubular part which is arranged so that it can be moved along the passageway in the bit body, the upper tubular part forming a passage with a downstream opening for the passage of at least a portion of the operating tool to a position external to the passage tool, when the lower part of the passage tool has been moved out of the bit body.