BP is partially evacuating an oilfield in the North Sea because a barge has broken loose from its anchor and is drifting out of control in rough weather.

It's Thursday night and the Spider's Web pub is packed with beefy guys in windproof jackets and massive backpacks. The exhausted oil rig workers pile their bags against the wall, play pool or just slump in the leather seats, knocking back pints of beer. But…