Could oil rigs be good for the ocean?

More than a thousand oil and gas wells off the Australian coastline are nearing the end of their lives. Once they're decommissioned, it'll fall to the extractive industries to foot the $50 billion clean-up bill. There is a cheaper alternative though: for half the price, they can leave everything more or less exactly where it is. Today on The Signal, are these companies just pitching an elaborate version of ocean dumping? Or could it somehow be a win for the environment too? Featured: Mikey Slezak, ABC National Science, Technology and Environment Reporter