Global strategic petroleum reservesApparently not that much of a big deal: I found that IEA member states have about 1.5 billion bbls that are government-controlled (there is much more reserve than that, obviously, but the rest is controlled by oil companies).
So at 100 million bbls/day, that's a HUGE 15 days worth of suppply.
The US has the largest reserve, at about 606 million bbls...