Ugly duckling refineries turning into swans

London

OIL companies' least-loved business over the past five years is proving to be their lifeline.

Margins from refineries in north-west Europe rose fivefold last quarter to the highest since at least 2003, data from Total SA show. In the preceding quarter, the share of profit from processing crude and chemicals at Royal Dutch Shell and BP was four times higher than the same period a year earlier.

The turnaround follows last year's end to an oil boom that tripled the cost…