Thackney knows a lot more than I, and Smokin' Joe here in the Bakken too.
But living in the area you hear the same thing from the oil men, some of the good ones, that the amount of oil still likely recoverable is staggering.
A fellow who works for one of the big companies told me that much of it might not be available through present technologies; but given the quantities that appear to be there, he said, they will find a way to get it.