Ann: Cooper Basin Project Update , page-13

Opaline,
I think you are right, there are a number of obstacles to deal with,
5" drill pipe,
Bottom hole assembly consisting of 6 1/2" drill collars and then a couple of 8 1/2" stabilisers, maybe a motor and then the drill bit. The larger diameter stabiliser and bit can't be washed over.
I guess the course of action is washover the drill pipe and possibly the drill collars to recover as much as possible, this is faster than drilling a new side track hole, then try and yank the remainder but it is probably stack fast with angular chips of granite wedging it, so after a few attempts set a wedge and drill a new hole.