The start-up of a giant new oil field in Norway’s part of the North Sea has led to a surge in shipments from the region to Asia.

About 18 million barrels of North Sea oil got shipped to Asia last month, more than double October’s levels, according to tanker tracking compiled by Bloomberg. That’s almost certainly the highest flow ever. A third of last month’s cargoes were of the new Johan Sverdrup grade, which has become the North Sea’s largest oil stream, overtaking Forties crude.

The Johan Sverdrup field, operated by…