The soaring cost of moving oil around the world is making some long-distance crude trades uneconomical, threatening to disrupt flows at a time when fuel markets have never been tighter. The jump is being driven by a shortage of available supertankers, with barely any ships left for hire in some parts of the world.

Moving a cargo from Houston to Asia now adds about $26 a barrel — $52 million a cargo — to the cost of supplying the world's largest crude-importing region. That's equal to roughly a quarter of the price of West Texas Intermediate futures. Before the war, shipping typically accounted for only a tiny fraction of the cost.

The rally is minting fortunes for the small group of shipowners that dominate the tanker market. The value of the world's largest oil tanker equities soared to a record of almost $70 billion this week.

On the industry's main benchmark route, very large crude carriers hauling 2 million barrels of crude from the Persian Gulf to China are earning upward of $1.2 million a day. US-Asia flows have fallen in recent weeks, as freight costs roughly tripled.