Undereaming/Bi Center Bits

Wonder if anyone has experience of undereaming through fractured /
karsified limestone or of using a bi-centre bit to open hole
through same.

We're planning to hole open whilst drilling, from 10 5/8" to 12" or
12 1/4" through 400m+ of limestone.

Looking at using a 435 insert bit if we go with the undereamer.

Any suggestions or advice much appreciated.
2 Answer(s)

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