TEHRAN/WASHINGTON — April 28, 2026: Iran is facing tightening storage capacity for unsold crude oil following a sharp decline in exports after the United States imposed a naval blockade on April 13, restricting tanker access to key ports in the Persian Gulf and the Strait of Hormuz.
According to shipping data cited by The Wall Street Journal and commodity analytics firm Kpler, Iranian crude and condensate loadings averaged approximately 2.1 million barrels per day between April 1 and April 13. After the blockade took effect, exports dropped significantly, with only five cargoes recorded between April 14 and April 23, reducing average loadings to about 567,000 barrels per day.
The decline in exports has led to a rapid buildup of oil inventories onshore. Estimates indicate that stockpiles increased by roughly 4.6 million barrels during the blockade period, bringing total stored volumes to around 49 million barrels. While Iran’s theoretical storage capacity is estimated between 86 million and 95 million barrels, operational limitations reduce the amount of usable space.
Kpler assesses that Iran has between 12 and 22 days of remaining onshore storage capacity before reaching maximum levels, commonly referred to in the industry as “tank tops.” The country’s main export terminal at Kharg Island, which has an estimated buffer capacity of 20 to 30 million barrels, is filling more quickly due to reduced tanker departures. Earlier in the year, Iran also maintained floating storage of about 127 million barrels, although part of this volume has already been utilized or committed.
To manage the surplus, Iran has begun deploying alternative storage and transport measures. Authorities are reactivating older, previously unused or poorly maintained tanks—often described as “junk storage”—in southern oil hubs such as Ahvaz and Asaluyeh. In addition, improvised containers are being used to hold excess crude.
Offshore, Iran is expanding floating storage by bringing retired oil tankers, including vessels around 30 years old, back into service. These ships are estimated to provide an additional 15 million barrels of temporary storage capacity in the Persian Gulf.
Iran is also exploring overland export options to bypass maritime restrictions. Efforts are underway to transport crude by rail toward Chinese commercial centers such as Yiwu and Xi’an. However, analysts note that higher transportation costs could reduce demand from China’s independent refineries, which previously accounted for the majority of Iranian oil imports.
Despite the blockade, limited export activity has continued. TankerTrackers.com reported that approximately 4.6 million barrels were loaded at Iranian terminals in recent days, with an additional four million barrels appearing to have passed beyond the blockade zone. The U.S. Central Command has stated that multiple vessels, including oil tankers, have been intercepted or redirected since operations began.
To prevent storage overflow, Iran has already begun reducing crude production from pre-blockade levels. Kpler projects that output could decline by as much as 1.5 million barrels per day by mid-May, potentially lowering total production to between 1.2 million and 1.3 million barrels per day.
Energy consultancy Rystad Energy has indicated that such production cuts may pose technical risks. A significant portion of Iran’s oil fields operate with low reservoir pressure, and abrupt shutdowns in these conditions can damage wells and complicate the resumption of production.
Before the blockade, Iran exported around 1.8 million barrels per day in March, primarily to Asian markets led by China. The current restrictions are part of broader U.S. efforts to limit Iranian oil trade, with ongoing impacts on the country’s production, storage, and export logistics.
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