As I recall FDR met with the King of Saudi Arabia on a military ship in 1945. I don't recall the significance of the meeting, but it built stronger political-economic ties between the two nations. This video describes the history of the Petrodollar concluding the commonly told story to be a myth:
After World War II the global banking system began to create Eurodollars: offshore dollar loans that tie back to the US commercial banks via what I call a daisy-chain in the respective balance sheets and accounting customs. The Eurodollar loans made by financial dealers around the globe, but particularly in European money-centers, represented an offshore money multiplier for the global US dollar. Eurodollars are the more compelling story of the emergence of the global dollar. Petrodollars grab more headlines, and so do large volumes of offshore dollars that some politicians argue should be repatriated for domestic purposes, but the repatriation argument is a financially infeasible pipe dream.
Joe