Hole-opening pilot holes : Hole-opener vs. bit

15 April 2012 Hi folks,

At a recent DWOP, we were discussing how best to hole-open (to 26") a 12-1/4" surface pilot hole, drilled largely through volcanics. Hole is vertical.

The current plan is to use a 26" bit with no MWD capability. However, there was concern about whether or not the 26" bit/assy could be relied upon to follow the pilot-hole. The topic turned to using a hole opener assy instead.

I'd be interested in members' experience of opening a pilot-hole using a bit only. In our case it's relatively soft formations, but it would be good to expand the discussion to include harder formations as well.

Many thanks

Dave Taylor

8 Answer(s)

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