Energy Secretary: "the days of easily accessible oil are coming to a close"

Having more, and better, information about reserves would also clarify some of the challenges we will be facing in developing future petroleum reserves. We believe that the days of easily accessible oil are coming to a close. That is already the case for the lower 48 in the United States. Increasingly, the global oil demand will have to be met by developing petroleum resources that involve serious technical, and often political, challenges.
The technical challenges, of course, include drilling in deep waters and other harder-to-reach, frontier regions as well as enhanced oil recovery technologies such as CO2 injection and thermal processes. All of which means that such projects will be more capital intensive, have higher risks, and require greater lead times. These are difficult circumstances in and of themselves. But the challenges are multiplied several times over when compounded by political or regulatory uncertainty.