The blockade is biting
Iran's main oil export terminal at Kharg Island, the small Persian Gulf outcrop that handles roughly 90% of the country's crude shipments, was 74% full as of April 20, according to data from commodity analytics firm Kpler. The industry typically treats 80% as the operational ceiling.
That leaves around 13 million barrels of breathing room. At the rate tanks have been filling since the US naval blockade began on April 13, Kpler estimates Iran has 12 to 22 days before it runs out of space. Wood Mackenzie puts the timeline at roughly three weeks.
After that, Tehran faces a choice it has been trying to avoid: shut wells.
Exports have collapsed
Since the blockade took hold, crude and condensate leaving Iranian ports has fallen to about 567,000 barrels per day, down from 2.1 million bpd before the cordon went up, tanker-tracking data shows. Iran still pumps more than 3 million bpd, but domestic refineries can only process about 2.6 million bpd. With export routes largely sealed off, the extra crude is piling up onshore.
Treasury Secretary Scott Bessent said on April 22 that Kharg Island storage would be full "in a matter of days." That call was premature. Some oil has trickled out through Iran's improvised Hormuz toll system and via tankers willing to risk US sanctions. But the trend line hasn't shifted.
Wells that shut down may not restart easily
The deeper concern for Tehran isn't the short-term revenue loss, which the White House pegs at $500 million a day, but what happens underground.
"Those oil wells are not maintained well," said Miad Maleki, an analyst at the Foundation for Defence of Democracies. "They won't easily snap back."
Alexandre Araman at Wood Mackenzie warned that shutdowns exceeding one month "risk long-term damage" to reservoirs. Iran's aging fields, many of them decades old and already in decline, could lose output permanently if forced offline for an extended stretch.
The pressure cuts both ways
Iran still holds cards. An estimated 160 to 170 million barrels of Iranian crude sit on tankers at sea, and former Congressional Research Service analyst Kenneth Katzman told Al Jazeera that revenue from those floating cargoes could keep Tehran going "until August."
Iran has put a Hormuz-for-blockade deal on the table, offering to reopen the strait if the US lifts the naval cordon. Trump has so far refused, insisting on a complete nuclear agreement first.
Brent crude traded at $108.63 on Thursday, down 1.63%, while WTI fell 3.25% to $101.76. Traders are watching Kharg Island storage data closely. Forced Iranian production cuts would pull barrels off a market already stretched thin by the Hormuz closure.
What to watch
Kpler analyst Muyu Xu said production cuts would likely start "gradual," but could pick up speed through May if the blockade holds. The next signal: whether loading rates at Kharg drop below 500,000 bpd, which would suggest wells are already being throttled.