This is a really bad summary of the original statement by Continental Resources. They didn't claim the oil that could be produced was raised by 57%, they said the original oil in place estimate was increased by 57%, not the same thing.
Continental estimated in late 2010 that the Bakken field would eventually yield 24 billion barrels of oil equivalent (Boe), based on technology available at that time. This estimate included 20 billion barrels of oil and 4 billion Boe of natural gas, and assumed 577 billion barrels of original oil in place in the Bakken and TF1. With the addition of oil found in the lower Three Forks benches, which includes the TF2, TF3 and TF4, the Company now estimates the field has 903 billion barrels of original oil in place, a 57 percent increase.
http://phx.corporate-ir.net/phoenix.zhtml?c=197380&p=irol-newsArticle&ID=1763542
Never underestimate the technical ignorance and lack of arithmetic skills of the “real” news reporters employed by the State-run Media.