Luciano.....for differential sticking to occur you need two...

Luciano.....for differential sticking to occur you need two things - permeability and an overbalanced mud system.I really believe that the original well bore was highly overbalanced and the despite the adjustment in mud properties the side track was also overbalanced.

Thank you Kiwigeo I seem to recall SM mentioning that they did go down ST with slightly underbalanced Midweight, and that eventually differential sticking happened due to high porosity pressure, may be it occurred because of the length of time the hole was left open ...?!
Thank you anyway.