Cheap oil has passed, never to return. Lots of oil is locked up in oil shale, true, but it is exceedingly expensive to extract and refine. The production costs of oil shale and Canadian tar sands are such that energy-industry corporations understand that it would probably cost more energy to extract and refine those two sources than the energy produced. The only way they will ever be (theoretically) profitable to use those two sources would be when the price of energy is so high it might pay to develop them. Yet, "demand destruction" would also ensue: Demand nosedives because of the high price.
Same with future production of "plentiful" reserves of oil: There are huge amounts left that will never be used because of the price of extraction and refining. There will be all the oil we ever care to use at a price that will increasingly negate our use of it--demand destruction, again. That day will come soon, or so say many oil economists.
What you label as "environmentalists" are resource scientists, marine and conservation biologists, State tourism officials, the fishing industry, and State and local leaders who want to preserve biodiversity, marine habitat, fish stocks, local tourism, public health and a clean environment. Take a look at the preservation of the California Channel Islands and the myriad forces who were all for preserving the islands and surrounding habitat. It has never been only about "environmentalists."
Let me ask you a question. When an "American" oil corporation takes out a lease for future oil exploration and develops it--to whom must it market? If I obtain a fishing license from Mississippi (like an oil lease), and catch a fish (like extracting oil)--to whom do I sell my catch? It is a global market that the oil corporations market to; none of the oil is reserved for the U.S. market. It is a global market, not a dedicated one. (And, I sell my "American" fish to the highest bidder.)
The easy oil reserves are no more and the U.S. demands way too much for our economic viability. If you read Forbes, it marshals data recently that say lots of oil reserves remain in the U.S. True, as I said above; but those recent, extremely short articles and the data they use are oversimplifications which include oil shales and reserves on the outer continental shelf and even deeper waters that probably will never be extracted, not because of environmentalists, but because of economics.
Cheap oil is no more; and sufficient alternative-energy sources are probably many, very uncomfortable, years away. In the meantime we are sleepwalking through a hallucinated petroleum-based economy in which Nature will increasingly bite our butts in a deadly combination of destructions: environmental, resource, demand, economic, and social. Can psychological be far behind?
I have said that the rampages of global late-capitalism is a like a disease. More accurately it is not so much an "-ism" (or a disease) as it is a set of practices that, of course, has as its (unthinking) basis the making of profit no matter the environmental consequences. Disease, instead, is confined to social forms, cultural beliefs, economic practices, and human lifestyles which are non-sustainable. Surely, this does not require being 'liberal" or "conservative." Not when it is a matter of life and death.
The (mental) disease, then, is not knowing how to survive on a long-term basis. For that we can look to past civilizations, none of whom we can ask directly what they did wrong. Always, though, it probably was a matter of energetics: They depleted their energy sources (including food) without prescient and timely adjustments to their lifeways.
If we are counting on oil from the near (or even outer) continental shelf, then there is serious concern about the future of civilization as we know it now.