When you hear about news like that, remember that 1) a billion barrels is about 50 days of US consumption and the Us is less than half of global consumption 2) that the announcements are usually about "oil in place" which an estimate of the total size of the deposit, of which 10-40% is usually recoverable.

If you are talking about Alpine High, it's less than 1/2 a year of US consumption of oil and less than 3 years of US consumption of natural gas at current rates (and very likely less depending on the recovery ratio).