A severe shortage of supertankers in the Persian Gulf has created a looming crisis that could force oil producers to shut in production. Only six to 12 very-large crude carriers remain available for hire in the region, according to ship-tracking sources and Oil Brokerage Ltd. These vessels, which aren't on any blacklists, are being snapped up at soaring rates.

Typically, 15 million barrels of crude are loaded daily in the Gulf for export through the Strait of Hormuz. With each VLCC carrying two million barrels and requiring two days to load, the available fleet falls far short of handling even one day's exports. Most producers have minimal storage capacity at major loading terminals, raising the possibility that Saudi Arabia and other Gulf states may need to halt output.

The situation has been exacerbated by South Korean shipowner Sinokor's recent acquisition of many VLCCs, with six of the available supertankers now controlled by the company. While Saudi Arabia, the UAE, and Iran could divert some production via pipelines to ports outside the Gulf, these volumes are small compared to flows through Hormuz.