The United States is oil rich. 1 Trillion barrels. However, our oil has not matured yet and is still oil shale. It would take millions of years before it would be in a state where we could easily draw it out. Companies have been working on speeding that process up but it is expensive and resource intensive. Still the high oil prices have the government and businesses taking another look.
Article Here.
Chevron's Deepest Well Holds Less Oil Than ForecastArticle states that it only has 200 to 500 million barrels in their Knotty Head field.