Kpler, a data and analytics firm, said Iran could fill its crude storage in 12 to 22 days if the US naval blockade continues. The blockade has been in place since April 13 and has interrupted seaborne exports routed through Kharg Island, where most of Iran’s crude that moves by sea is loaded. Tehran has limited passage through the Strait of Hormuz and is refusing foreign-flagged ships until Washington lifts its interdiction. If storage fills, Iran may have to scale back production gradually while political and market effects ripple outward.

How the blockade has constrained exports

The United States began a naval interdiction of vessels linked to Iran on April 13. Ships carrying oil to or from Iranian ports have faced redirection. US forces opened fire on and then seized an Iranian-flagged tanker near the Strait of Hormuz, according to official accounts. Those moves have cut off a major export route for Iran’s crude.

Kharg Island is the hub for Iran’s seaborne oil sales. About 90 percent of Iran’s crude that moves by sea is loaded there. Iran is the third-largest oil producer inside OPEC, after Saudi Arabia and Iraq. That combination gave Tehran a steady outlet for most of its crude until the interdiction began.

With exports interrupted, produced oil needs temporary storage. Kpler’s analysis shows storage is limited. The firm said tanks could be full within 12 to 22 days if shipments don't resume. United States Treasury Secretary Scott Bessent has also said storage at Kharg Island would be full "in a matter of days." Those statements line up on the same risk: produced crude has to go somewhere.

What Iran has done at sea

Iran’s military posture around the strait has changed since late February. On Feb. 28, following air strikes by the US and Israel, Ebrahim Jabari, a senior adviser to the IRGC commander in chief, declared the Strait of Hormuz closed.

He warned vessels that they could be attacked if they tried to pass without permission.

In the weeks since, Tehran has at times allowed some ships to transit. It said it would let through vessels that it deems friendly or that pay fees. But officials now say foreign-flagged ships can't pass until Washington lifts its own naval blockade. Iranian First Vice President Mohammad Reza Aref posted on X that Iran won't accept restrictions on its oil exports while others demand free security in the waterway. He wrote that either the market for oil must be free for all, or there will be costs for everyone and instability for fuel prices.

Why storage limits matter

Storage capacity determines whether a producer can keep pumping when exports stop. If storage is available, production can continue while shipments are paused. If tanks fill, the producer faces a choice. It can halt output, which takes wells offline and affects workers and contractors. Or it can keep pumping and risk spills or costly emergency measures to move crude to nontraditional outlets.

Mastheads

Analysts cited by Kpler say Iran could gradually scale back output if the blockade persists. That would reduce the volume of oil entering global markets. The strait itself is already a chokepoint: about 20 percent of world oil and LNG trade passes through the channel during normal times. Any further restraint on flows sharpens market pressures.

Political and economic implications

The interdiction has immediate political aims. Washington says it's trying to curb Tehran’s ability to fund military operations and to pressure Iran diplomatically. Seizing tankers and redirecting ships is meant to choke revenue tied to maritime trade. Iran frames its moves as defensive and warns that closing the strait raises costs for others.

On the economic side, the disruption cuts two ways. Sellers lose access to normal buyers. Buyers lose predictable supply routes. That raises costs for shipping, insurance and logistics. Higher transport costs tend to show up in refined fuel prices and in the margin structures of oil traders. For countries that rely on Gulf flows, the effects are direct. For the United States, the pass-through works via global oil markets and fuel prices.

US officials have publicly framed the blockade as enforcement of sanctions and maritime security. The seizure of a tanker sends a strong signal that Washington will act at sea. That posture increases the chance of confrontations with Iranian forces and with neutral third-party ship operators. Each confrontation carries the risk of further retaliatory measures or legal disputes over seized vessels.

Pumping crude is one task. Storing it's another. Storage at Kharg Island and elsewhere in Iran is finite. Iran’s oil ministry and state companies must manage tanks, pipelines and loading berths if exports are disrupted. Moving crude to floating storage or offloading to third-party ships is possible but costly and complex given the naval interdiction.

If Iran stops some wells, that affects service companies and engineers who maintain fields. Restarting shuttered wells can take time and money. Gradual production cuts would therefore change not just export volumes but the internal economics of Iran’s oil industry. The source material notes experts expect a phased scaling back rather than an immediate full halt if storage runs out.

Shipping through the Strait of Hormuz is integral to world energy trade. Any additional choke points or seizure events force shippers to reroute or suspend voyages. That means higher insurance premiums for tankers and longer voyage times. In turn, those costs get passed along to refiners and end users.

Political risk can also change how companies operate in the Gulf. Firms may avoid Iran-linked cargoes. They may seek alternative suppliers or routes, which raises demand pressure elsewhere. Countries that import Gulf crude face short-term volatility in supply and pricing. The US exposure is mainly through global market prices and through its own strategic petroleum reserve planning and naval commitments in the region.

US seizures and Iranian threats create diplomatic friction with states whose ships transit the strait. Countries with large merchant fleets may face decisions about whether to accept higher costs or to challenge interdictions legally. Iran calls the US actions illegal and has labeled some moves as piracy. Washington treats them as lawful interdiction tied to sanctions enforcement and security objectives.

Those competing claims make maritime law disputes more likely. They also complicate third-country relations with both Tehran and Washington. That political arithmetic matters because neutral coastal states and ship registries play a role in keeping ocean lanes open.

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Kpler said Iran's crude storage could fill in 12 to 22 days if the blockade persists, likely forcing gradual production cuts unless shipments resume.

This article was created with AI assistance.