Why does the US Government and especially the Democrats hold our own OIL hostage?

Canada has also the largest oil reserves on the planet but the problem is it is in rock. The process to extract oil from rock is very, very expensive. The high oil prices now would probably justify it now but how long for. It is also the dirtiest way to get oil making pollution a big problem. in Saudi Arabia the oil is nearly on the surface and is cheap to get.