The night sky over the port of Rotterdam was alight after the blaze broke out Saturday at the high-voltage power station at Shell's Pernis refinery.
Shell spokesman Thijs van Velzen said the flames were extinguished by Sunday morning. Nobody was injured. Firefighters brought the fire under control by around 6 am (0400 GMT/UTC).
The British-Dutch oil giant would not confirm media reports that the fire may have been sparked by a short circuit. The company said it wanted to "wait to know more about the circumstances of the incident" before commenting on its cause.
Shell said there were no casualties as a result of the fire, which had been brought under control. Most of its production was shut down.
The outage at the Rotterdam plant was expected to boost prices of oil products such as diesel, jet fuel and gasoline in northwest Europe.
A massive refinery
According to the regional security authority, there were no toxic materials in the smoke.
The Pernis refinery in Rotterdam's sprawling port has the capacity to refine more than 400,000 barrels of crude oil per day.
The shutdown prompted Shell to burn off excess gases at the plant, a process known as flaring. The move sent large flames into the sky on Sunday.
The massive refinery covers an area equivalent to 800 football fields, and its pipework, if laid end to end, would be long enough to circle the Earth four times.
After a jump in profits
On Thursday the company reported that its second quarter net profit jumped 31.5 percent to $1.5 billion (1.3 billion euros) from a year earlier, propelled by higher oil prices.
"Shell's strong results this quarter show that we are reshaping the company following the integration of BG," chief executive Ben van Beurden said in an earnings statement, referring to the Anglo-Dutch company's purchase of British peer BG Group in 2016.
bik/jm (AFP, AP)