Exploiting Brazil’s untapped offshore oil reserves will be huge undertaking, and some companies will likely get hugely rich. If you want an idea of the colossal amounts of money involved, check out the details in this otherwise unremarkable bit of news: Shares of the deepwater driller Enco rose 2.3 percent yesterday after it closed a deal to move just one of its drilling units to Brazil. Rental on the deepwater rig is going to be $320,000, per day, for period of 950 days.