PDC Under-reamers - Bit-BHA-UR systems approach

11 March 2014 With more exotic contingency strings being planned, PDC under-reaming is becoming much more common and successfull so I am informed.

We are therefore looking at planning, engineering and working to be able to under ream (as a contingency) in what will be a "Cretacous formation" potentially 700-800m sequence on a offshore well, from a floating rig, at a tangent angle of 38deg in hole size potentially from 8½ to 13½ using SOBM.

Lessons learned?, recent experiences?, knowledge gained items to discuss with manufacturers etc, appreciated.
- optimal bit under reaming configuraiton
- stabilisation on lead bit and behind undereamer
- weight and length below under-reamer?
- under -reamer preferences (size of cutters?)
- flow balancing, nozzling preference
- drilling measurement tools below under reamer (benefits seen?)
- operating hazards, risks to watch out for an how to best mitigate these?

6 Answer(s)

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