Don’t use words like immense. Use specific numbers, and with specific API viscosity quotes. Shale is light tight oil. Urals is not. One is diesel rich with constituent proportions up near 40%. The other is not. Guess which.
80 million year geology doesn’t care about politics.
Well, you can look it up for yourself.
https://www.worldometers.info/oil/oil-reserves-by-country/
Just one of many sources. Reserves are a difficult number to take seriously as there is no consistent procedure for determining reserves, and it tends to change rapidly with changes in tech and soft factors, such as investment climate, regulation, political risk premiums, etc.
Petroleum is a fungible international commodity moreover. The US, with its naval dominance, is able to command most global resources at need. The British with the RN and its domination of the global trading system was able to do so also, in its day.
I therefore defend the use of “immense”. Lets take it to mean “far more than sufficient for our purposes”. A lack of petroleum will not constrain the operation of US forces or its economy in any conflict we can contemplate in the next few decades at least.
API viscosity is (almost) irrelevant to this question.
Refineries are able to vary the yield of different products considerably given their feedstock. The US uses a larger fraction of gasoline in its civilian economy. In any case the potential needs of diesel for military operations are always going to be a small fraction of civilian needs for ither oil products.
Your argument amounts to a quibble.