> "Since the oil price crash, investment in exploration has gone down dramatically, so I would argue the contrary...."
The fracking technology for oil and gas is still on it's Moore's Law curve and is getting cheaper and cheaper so in fact more and more fracking is coming on-line so that we're unlikely to see prices much above $50 per barrel.
Good point. It just occurred to me that the spectre of shale that you highlight also counter-incentivises exploration, perhaps more so than alternative energy.