From 1972 to 1974, the U.S. government made a series of agreements with Saudi Arabia. These agreements created the petrodollar system.
The U.S. government chose Saudi Arabia because of its vast petroleum reserves, its dominant position in OPEC, and the (correct) perception that the Saudi royal family was corruptible.
In essence, the petrodollar system was an agreement that the U.S. would guarantee the survival of the House of Saud.
-Nick Giambruno
Read on:
https://www.lewrockwell.com/2016/01/nick-giambruno/watch-petrodollar/