I have a hard time seeing a severe shortage. The Permian Basin alone is producing about 40% of the US production. New wells in the Permian Basin are only recovering 9-11% of the oil in place. We will get better. Just a few percent of improved recovery will make a big difference, so much that I see it easier to step up production through better reservoir engineering than increased exploration (where I spent my career). Price is a big factor. Current production is from locations in which with current technology they make a profit down to around $40/barrel. If there is confidence of sustained $80 prices, the number of viable drilling locations soars. Above $100 long term, we could go into a glut, all without opening up new discoveries.