Ah, the petrodollar bullshit again.
Do yourself a favour. You've spent enough time on all the conspiracy theories (you feel like you're in on some special knowledge), spend an evening going through the results from Googling petrodollar debunked, or 911 debunked, or fractional reserve banking debunked. These conspiracy theories do have grains of truth to them, but they're mostly bullshit.
So why is the USD a defacto world reserve?
The Petrocurrency explanation is, roughly, contributing factor number 9 or 10 on a much longer list.
Firstly, understand, that oil is trading in other currencies, ALL THE GODDAMN TIME, in substantial portions.
1 - the US still accounts for about a quarter of the world economic activity. And despite what you may think about the US not making anything anymore, the US still makes about 20% of the world's manufactured goods price-wise. No, the US doesn't print a billion t-shirts or make huge volumes the way China does. The US tends to manufacture much higher end stuff. The sort of stuff that governments around the world, or large corporations attached to governments, want to buy. Like sophisticated weaponry, precisely engineered machine tools, mining equipment, medical equipment (like MRI machines), farming machinery, etc. You need USD to buy these. Not to mention agriculture. The US is a huge exporter in agriculture.
2 - the US trades in a great many intangibles, like political and diplomatic favours, information, intelligence, etc.
3 - the US Navy controls the world's shipping lanes, and therefore the bulk of the world's international trading system.
4 - geopolitical stability: the US has the world's best moat (Atlantic and Pacific Oceans), and has borders with who? Mexico and Canada...wow, who cares. The US is very safe and stable geopolitically. It is a very safe place to put your money. Buy T-Bills. The US has never defaulted on those; it can be argued that the US Treasury did actually technically default once in it's history during the introduction of computer systems but whether or not the US did default in that instance in the 70's depends on whether you ask from an accounting point of view or a legal point of view, since it was all settled out of court.
There's 4 big ones, but I wouldn't even be inclined to make number 5 that oil mostly gets traded in USD, since the US imports so much oil. There's nothing special about that.
Is the US involved in conspiracies? OF COURSE IT IS! The CIA's JOB is to be balls deep in running conspiracies. But this simple-minded bullshit about petrodollars is as bad 911 truthing.