According to one study by the United States Geological survey, 86 percent of oil reserves in the United States are the result not of what is estimated at the time of discovery but of the revisions and additions that come with further development.
Daniel YerginBut that's not enough: To maintain energy security, one needs a supply system that provides a buffer against shocks. It needs large, flexible markets. And it's important to acknowledge the fact that the entire energy supply chain needs to be protected.
Daniel YerginThe bulk of extra supplies that could be put into the market come from two places. One, they come from other Persian Gulf suppliers, of which Saudi Arabia is at the top of the list.
Daniel YerginBut the key thing is that Iraq, while it's got very large oil reserves, has marginalized itself as an oil exporter and these days its exports are only about one tenth that of neighboring Saudi Arabia.
Daniel Yergin