Russia’s war on Ukraine has redrawn the global oil map, rerouting a fleet of skyscraper-size tankers on longer voyages as they shuttle crude shipments that are essential to the global economy. 

The Wall Street Journal analyzed data from the ship-tracking firm Spire Global that showed the paths of about 3,000 such vessels to find those leaving Russian ports across periods before and after the Russian invasion on Feb. 24. Using location-tracking signals shared by ships and authorities, the information shows how fallout from the invasion cut longtime trade ties and left the Kremlin rushing to find the money it needs to fund its war machine. 

So far Russia has been able to redirect many of its crude exports, but they are selling at a steep discount to a handful of buyers including India, China and Turkey. Longer shipping routes captured by Spire Global data, meanwhile, have stretched the global tanker market thin as a “shadow fleet” of ships emerges to help Russian exports skirt widening Western sanctions.

In February, the reshuffling will continue with a U.S.-led price cap and European Union embargo on diesel and other refined fuels from Russia. The Journal’s analysis of crude shipments offers a preview of why next month’s changes, which analysts say will pose even more complex logistical challenges, are injecting fresh uncertainty into energy markets.

Write to Dan DeLorenzo at dan.delorenzo@wsj.com and David Uberti at david.uberti@wsj.com