Any cementing issue with long rat hole

05 April 2008 I plan to directional drill and underream 17.5"x20" hole for 16"
casing using RSS and underreamer. Hole inclination is between 30 - 55
degree. The underreamer will be placed +/- 25 - 30m above the bit
(above LWD). The section will be drilled with SOBM. Team has concerns
about cement quality around the shoe and well bore stabity in the
rathole if we set the 16" shoe above 17.5" hole. The current practice
is to run another trip to open up the rat hole to 20" prior to running
16" casing. The questions for forum are as follows:

1) Does anyone have the same experience and run casing +/-30m off
bottom? Any problem with LOT and hole problem while cleaning out rat hole?
2) What is the best practice? commit to additional rat hole open up
trip or set 16" casing off bottom?

Thanks.
Chakrit

5 Answer(s)

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