Kiwi and Geo,just to add my 2 centsThe pipe in this case would...

Kiwi and Geo,
just to add my 2 cents

The pipe in this case would have been stuck by chips of granite approx 1/2 to 2 cm diameter which settled and packed off around the BHA. This would probably have occurred when circulation stopped when a new pipe was being added. Although there are standard methods to minimise this risk, it will always happen from time to time. GDY's decision to drill bigger holes allows the use of beefier equipment, as you recall the skinny 3.5" pipe in the 6" hole was too delicate.
Being granite there are a number of problems not normally encountered when drilling sedimentary rocks.
The use of surfactants and other filtercake softening agents are inaffective, there is no filtercake in granite, there are no formation clays, no sticky or swelling shales. It's just granite. When it packs off it jambs for good, that's it. The next step is as mentioned by others is to back-off and side track. Normally in oilwells a cement plug is set and when the bit is run in it will drill off into the softer wall. However being granite, they will have to set a wedge or whipstock, (which is harder than the granite) and away they go again with a new hole. They've done it many times and got it down to fine art, this won't be any different. (google whipstock)