How low with US petroleum reserves get to ease the price shock from the Iran war? The units are millions of barrels.

The US Strategic Petroleum Reserve as of August 7th is 298.7 million barrels, down from 415 million pre-war.

President Trump authorized the Department of Energy to release 172 million barrels from the Strategic Petroleum Reserve, beginning next week. This will take approximately 120 days to deliver based on planned discharge rates 

https://www.energy.gov/articles/united-states-release-172-million-barrels-oil-strategic-petroleum-reserve)

This market resolves based on the weekly values officially reported by EIA - a historical overview is at 

https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=WCSSTUS1&f=W

Weekly U.S. Ending Stocks of Crude Oil in SPR  (Thousand Barrels)

A lower resolution version of the market: