North Sea oil fields connected to the Brent oil pipeline have stopped production due to a shutdown at the U.K.’s Sullom Voe oil terminal, the Brent pipeline operator said, reducing output of the crude which helps underpin a global pricing benchmark.

The Brent stream is scheduled to load almost 100,000 barrels per day (bbl/d) of crude in May and is usually the smallest of five crude grades that underpin the Brent benchmark, which is used to set prices worldwide.

“As a result of a shutdown at Sullom Voe Terminal, production has ceased from all Brent System and Ninian pipeline entrants, which includes all TAQA northern North Sea assets,” oil company TAQA, which operates the Brent pipeline, said in an email.

The terminal was expected to reopen on April 29, a source familiar with the matter said. It was not possible to confirm the exact amount of production affected.

The incident follows unplanned outages of another crude grade underpinning the Brent benchmark, Forties, earlier this year and in 2017. The outage of Forties, much larger than Brent, helped boost world prices.

Brent is almost a quarter the size of the 400,000 bbl/d Forties system.

Sullom Voe terminal is operated by Enquest. A company spokesperson said it spotted a fault on April 24.

“During a routine visual inspection of the process pipework within the Sullom Voe Terminal, a minor defect was identified requiring immediate remedial work, which is underway,” Enquest said.

“With safety as our top priority, we carried out a controlled shutdown of the incoming Brent and Ninian pipeline systems. There is no risk to people and no impact to the environment. We have advised terminal users and will keep them regularly updated with progress,” Enquest added.

Oil trading sources said earlier that one 600,000-bbl Brent cargo due to load in May has been dropped from the loading schedule and another was delayed into June.

Offshore