Exxon Mobil and ConocoPhillips -- who fled Venezuela last week after refusing to agree to President Hugo Chavez's more nationalistic terms -- are already among the biggest oil sands players. They know well that new projects take years to build as the rush to exploit the unconventional resource fattens costs and schedules.

"I think everybody in the investment community understands it's not easy," FirstEnergy Capital Corp. analyst Martin Molyneaux said. "It might be easy mathematically, but execution-wise it's unbelievably challenging."