When Daniel Lacalle, in his early 20s, took a job with Spanish oil company Repsol YPF SA in 1991, friends chided him for entering a field with no future. "They all said, 'Why do you want to do that? Don't you know only 20 years of oil is left in the whole world?'" he recalls.
Two decades and four energy crises later, the U.S. Geological Survey estimates that more than 2 trillion barrels of untouched crude is still locked in the ground, enough to last more than 70 years at current rates of consumption. Technological advances enable companies to image, drill and shatter subterranean rocks with precision never dreamed of in decades past. Trillions of barrels of petroleum previously thought unreachable or nonexistent have been identified, mapped and in many cases bought and sold during the past half decade, from the boggy wastes of northern Alberta, to the arid mountain valleys of Patagonia, to Africa's Rift Valley. Read More