Does the US have untapped oil reserves in the western states like Utah and Wyoming?

There are oil reserves worldwide that aren't currently tapped for one specific reason: it's not economical to. An energy company isn't going to go into the hassle of creating a producing well if they're not going to reap a financial benefit from it.

A good example of this is heavy oil, which as of a few years ago was considered the new "gold mine" of the oil industry. There are trillions of barrels in heavy oil reserves worldwide, but it is a far more costly extraction method than conventional oil, which is why not many people outside of the industry have probably even heard about it. Aside of technological hurdles need to be overcome for this type of oil, the price needs to be high enough that a profit will be gained from its extraction.