The dollar is used as the currency for commodity traders because it is the most stable currency in the world and has been for many decades. During the "Grear Recession," Putin tried to get China to back up a stupid idea to trade for oil with their funny money. China owes no allegiance to the US, but the history of the Ruble is road full of potholes. China passed on the idea. Why? Russia actually has two currencies known as a Ruble. The "Certificate Ruble," is used for buying dollars. You need Certificate Rubles or a hard currency like a dollar to buy imported goods in Russia. many workers get regular Rubles, which some stores refuse to accept. Russia has strict rules against common people trading too much hard currency.
The "petro-dollar," deal, if it ever existed, would have expired decades ago. It is just fodder for right-wing conspiracy theorists, and nothing more.