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ins.: 2014-08-17 00:00; ( Age: 10 yrs )
By: Scientists
Category: COSC1

COSC: 2014-08-17

6 m of drill core were lost in the hole ...
The drill bit that was worn out by over-drilling 6 m of lost core.

6 m of drill core were lost in the hole (empty core barrel) last Thursday, before the round trip during which the gear box and rotation unit broke down. The drill core was standing at the bottom of the drill hole as whole, or more likely in pieces, and it was inevitable to over-drill the drill core with the new drill bit to catch it - with the risk that loose, rotating pieces of the lost core damage the drill bit. 3.5 m of the lost core could be retrieved. The missing 2.5 m are the first core loss in the COSC-1 drilling, at 2.2 km depth! The core pieces look really bad - oval, incised, with clear sign that large forces were acting on it. Thus, it wasn't a big surprise that the drill bit didn't last for more than 3 core runs.