It's getting increasingly difficult for Big Oil to move the needle on recoverable reserves, and the quest to discover the next giant oilfield has become outrageously expensive. For example, ExxonMobil (XOM 1.12%) is committed to spending $37 billion a year for the next three years. In this video, Fool.com contributor Aimee Duffy talks to Tyler Crowe about how this trend will lead to greater industry consolidation and analyzes what makes a good takeover target for Big Oil.