Well control after drilling with casing


I am struggling to get my head around an issue I am having with
casing drilling and request your help at the above time to help make
a decision as to the appropriate forward plan.

- The well has been casing drilled 3m into the Torro.
- The well is clean and the PDRT has been released and confirmed
- The casing has been washed over the drilling BHA to the top of the
underreamer, but the hole condition is such that it is not possible
to get the casing to the top of the underreamer without reaming,
which therefore negates the use of the standard casing hanger
(running tool is RH release).

Question. How do I recover the drilling BHA on drill pipe, while
still maintaining full well control, especially if there is not a
convenient casing coupling at the rig floor?

Useful information
Mwt expected to be 13.5ppg.
Drilling with 9-5/8" casing.
8-1/2" bit 1m ahead of underreamer arms.
Assume CRT still installed in TDS.
Assume nearest casing collar is in the air above the RT.
BOP has 9-5/8" casing rams in the middle ram blocks, with DP above
and blind below.
Split type SH3 wellhead installed on 13-3/8" casing.
CRT cannot take the weight of a 5" drill string. Its elevators and
bails are rated to 13,000lbs.

Cheers Mike
4 Answer(s)

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