Actually Neil_WA the closest refinery is not very far at all.... about 80 minutes drive from the flax rigs in a town called Moomba which is practically owned by Santos Oil and has an airfield as well as major pipelines running through and truck depots.
From Moomba a pipeline goes all the way to Adelaide... mind you all this is owned by Santos so negotiations would have to take place if the company decided to use existing infrastructure.