No France still needs X USD to send to Saudi Arabia for Y barrels of oil. The only way the USD becomes funny money is if SA buys X from France also denominated in USD so that the cycle is closed, otherwise France needs a continuous source of USD to send over to SA. [0]

[0] Simplifying to national here; yes it's not just one unit in France and one in SA but on net there's X trade between the major money movers in each country.