RE:white hills..... You can't really evaluate the oil potential of one area vs another without knowing things like reservoir pressures, local temperature gradients, cap rocks, shallow thicknesses, kerogen info, etc. You stated there's no permian aged rock. There is. You said it's all shallow coalbed gas. It's not (see section 1.2 of the below link). I'm simply correcting you on these falsifiable points.
And there's growing evidence of thick organic layers and deep depths in this particular region. This is called de-risking. We require seismic, cores, and logs before we can even indicate ONE of the above variables.
Please read the below article for primary sourced info on the matter. And please stop spreading misinformation.
Technically Recoverable Shale Oil and Shale Gas Resources: (eia.gov)