Reuters reported that Amin Nasser, CEO of Saudi Arabia’s state-owned Aramco, said that global commercial oil inventories have fallen to less than six billion barrels and that most of it is effectively not accessible; a situation, he said, that has put pressure on the oil market.

At the “Intelligence Energy Forum” in London, Nasser said that since the start of the Middle East crisis this year, more than one billion barrels of oil—mostly from onshore commercial stocks—have been released.

According to Reuters, the International Energy Agency is preparing to release 100 million barrels of crude oil and gasoline with the aim of curbing price increases. Nasser said only 10% or less of the available stocks can be accessed, which has made supplying 100 million barrels difficult.

The International Energy Agency estimates global oil demand at about 102 million barrels per day.

Mike Wirth, the CEO of Chevron, also said that the decline in reserve stocks has made the oil market more fragile. Reuters wrote that oil industry executives expect market turmoil to continue into next year, because rebuilding inventories while meeting global demand may take years.