As shale oil makes a comeback, the United States could outstrip Russia and Saudi Arabia to become the world’s biggest oil producer. But is this new boom in black gold sustainable? Fracking in Texas (Getty Images/S. Platt) Three years ago, the US shale oil boom appeared to be over, apparently starved to death when OPEC flooded the market with cheap oil. As prices plummeted from over $100 (€81) to $40 a barrel, shale oil production — the drilling and hydraulic fracturing (fracking) of unconventional oil deposits found in shale formations — quickly became uneconomic. In just under a year, more than 130 US shale producers, from Pennsylvania to North Dakota, declared bankruptcy, leaving tens of thousands of American oil workers without jobs. But the highly cyclical nature of the energy sector, and a rebound in oil prices to more than $60 a barrel, have helped revive the fortunes of […]