The NCPA !! Ha ha. Newt Gingrich's favourite think tank. Yeah right, I'll believe them.
Continental Resources would like you to think there is 900 billion barrels in there because then you would buy their shares.
However if you look at what the company tells the SEC in their filings (and they are more likely to tell the truth when dealing with the SEC)
Estimates of recoverable reserves for the Bakken field have grown from 4.3 billion barrels of crude oil, as published in a report issued by the USGS in April 2008, to potentially 11 billion barrels of crude oil in North Dakota alone, as reported by the North Dakota Industrial Commission (“NDIC”) in January 2011
Link from the following page, Download Annual Report.
http://phx.corporate-ir.net/phoenix.zhtml?c=197380&p=irol-irhome
it's a big pdf and they say 'potential' 11 billion barrels when they are made to say what they really think. So now only 899 billion barrels to find.
But feel free to buy their shares.