The drifting oil tanker that signals Opec's struggle

Washington

IF a single ship can capture the current state of the global oil, it's the supertanker Saiq, floating idly about 850 kilometres south of the Canary Islands.

Until a few days ago, the 330-metre-long tanker, chartered by Royal Dutch Shell, was steaming toward the Chinese port of Tianjin after loading a two-million-barrel cargo of North Sea oil at the Hound Point terminal near Edinburgh. Then, it suddenly stopped in the middle of the Atlantic Ocean, according to ship-tracking data compiled by Bloomberg.

Its problem: China isn't buying much crude right now, leaving the tanker searchi…