The US has targeted ISIS for a long time now, initially it was to destroy the US Supplied equipment disregarded by the regular Iraqi Army units. The US has been targeting Oil Fields for months, trying to dissect the financial income.
U.S.'s newest airstrikes target Syrian oil fields - Washington Times
If you think bombing oil fields or refineries is such a great idea, why hasn't the Protector of the Assad Regime and all things Shia taken them out? With the superior state of the art better weapon system than America's all Iranian made weaponry?
Unless you want pictures like this:
Or a dynamic environmental concerns,
i'm guessing you dont know how hard it is to clean up an oil spill?
NATO didn't strike the oil fields or refineries, they took out emplacements of Qaddafi's units around them. Even those strikes were by Qatari and UAE jets.
A question for you, Where are they shipping that oil to? Not Jordan or Lebanon or Iraq, but Turkey.