What is the actual value of the oil, gas and coal fields owned by big energy corporations, which gives them their stock price and allows them to be counted as assets for borrowing purposes?
The real value of those hydrocarbon resources is zero.
Or actually it is much less than zero, since there are likely to be a lot of liability lawsuits and insurance claims for severe environmental and property damage. Coal, oil and gas are now where the cigarette companies were in 1990, on the verge of getting hit with massive penalties. Big Coal and Big Oil are dead men walking.
The only thing that stops the entire world economy, including that of the United States, from collapsing is that investors continue to pretend that what I just said is not true. Because of this pretense, some people will go on making a lot of money with hydrocarbon investments in the short and perhaps even the medium term. Much investment and assignment of value is a matter of confidence.