Reserves are complicated.
On day 1 they will have a number. On day 10 the price has changed and the number will then be different. The SEC has created rules for defining reserves because companies put them on their balance sheet as assets. Meaning, that’s how they got involved. There are P1, P2 and P3 reserves.
The reality is the true numbers are defined by Geology, not the SEC. The official 1P proven reserves number for the US is 68 billion barrels. You’re off about 1.5X. The estimate is suspect regardless. 1P is economically practical and that can end even without a price cut.
Russia, of course, is at 107 billion and that does not include the Bazhenov shale.
Shale is not a technology reality. Russia was doing fracking as far back as the 1970s. Rather, it has been a zero interest rate reality. Borrowed money paid for unprofitable wells and there was no foreclosure. When this was seen, naturally the wells became profitable. If you have no interest expense, and no repayment schedule, it’s pretty easy to be profitable.
T Boone Pickens famous joke: An oil man walks into his lender’s office and sits down. The lender asks what happened on this well #1. The oil man says #1 has been a nasty problem. Some things happened we did not expect, but thankfully it could have been worse. The lender says I see, and what of #2? Oh, #2 was a different issue. A big disappointment for sure, but it could have been worse. The lender glares and says . . . #3? Oh, that #3 well has been both an annoyance and a disappointment. Hard to fathom, but thankfully it could have been worse.
How!!! How could it be worse? Oh, that’s easy. We could be losing our money instead of yours.
There are other ways. The notorious story of NPRA (Nat Petroleum Reserve Alaska) was assessed with reserves of about 9 billion barrels in 2003. In 2008 the USGS revised that. To 850 million barrels. A loss of 90%.
Natural gas is a much stickier reality. US nat gas reserves are 12.6 trillion cubic meters. Production (mostly consumption, some export) is about 1 trillion cubic meters/year.
Russia is the world’s big kahuna with 37 Trillion cubic meters. Production, 0.6 Trillion/yr. They will outlast pretty much everyone. And soon. #2 and #3 are Iran and Qatar. Their sum exceeds Russia, but it is all in one place, the big shared field under the Persian Gulf. Pretty easy to see how that could get erased.
When your civilization depends on what is underground, the country with the most ground is the wrong enemy.
This depends more on technology. That changes breakeven more than interest rates and prices, and reserve estimates.
In any case, on a long enough timescale tech matters much more than a mineral deposit. Petroleum wasn’t much of an asset until there were technologies that used it. And likewise its certain that tech will appear (and its happening as we speak) that makes it much less relevant.