| 摘要 |
A drill bit assembly comprising a bit body connectable to a tubular drill string, and provided with a longitudinal passageway for an operating tool f rom an internal position in an attached drill string to an external position ; an externally removable closure element for closing the passageway for the operating tool; and a passage tool attached to or connectable to the closur e element in its closing position from inside the bit body, wherein the pass age 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, t he upper tubular part forming a passage with a downstream opening for the op erating tool, when the lower part of the passage tool has been moved out of the bit body; as well as the use of the drill bit assembly in a method of pe rforming an operation in the wellbore.
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