North Sea Buzzard oilfield output down, 4th glitch of 2014 -sources

LONDON, Feb 4 (Reuters) - Output at the North Sea Buzzard oilfield was down, three trading sources said on Tuesday following an earlier glitch, the field's fourth output problem this year.

Nexen (KSE: 005720.KS - news) , Buzzard's operator, did not reply to requests for comment on output at the field, which plays a role in pricing global supply through its link to the North Sea Brent benchmark.

"Buzzard is down," said a trading source. Attempts were underway on Tuesday morning (Frankfurt: TDM.F - news) to restart output, a second trading source said.

The 200,000 barrels-per-day field is the largest contributing to the Forties crude blend, the most important of the North Sea crudes underpinning the Brent crude benchmark.

On Monday, two trading sources said there was an output glitch at the field. Details of the problem, and exactly when it began, remained unclear on Tuesday.

There have been three other output slowdowns or shutdowns at Buzzard so far in 2014, according to a Reuters tally based on information from trading sources and Nexen.

As well as boosting Brent prices, unplanned outages at Buzzard lead to higher price premiums of Brent futures for immediate delivery (LCOc1-LCOc2).

The first month contract was trading 64 cents above the second month on Tuesday, up from as low as 52 cents on Monday. (Additional reporting by Claire Milhench; Editing by David Evans)