London — The UK's Flotta crude oil supplies have been shut in for repairs after hydraulic fluid was found to be leaking from a valve, the pipeline's operator, Repsol Sinopec, said Thursday.

The shutdown is likely to compound tightness in the North Sea crude oil market resulting from disruptions to Norwegian supply, seasonal maintenance and reduced volumes entering Europe from outside the region.

Repsol Sinopec, a Chinese-Spanish joint venture, gave no indication of when supply would resume, adding that the issue was discovered last weekend at its Claymore platform, which also contributes to the Flotta crude stream and is a key part of the delivery infrastructure.

"We are carrying out repairs to a valve on the main export pipeline from Claymore to the Flotta terminal," the company said in an email. "This presents no threat to the integrity of the pipeline or risk of loss of hydrocarbon containment. However production is currently shut down on Claymore and from the other platforms in the area that come over Claymore."

Flotta is a blend of crude oil from several fields, the largest being Golden Eagle, operated by Nexen, a subsidiary of China National Offshore Oil Corporation (CNOOC). Output last year totaled around 59,000 b/d, although volumes have been in gradual decline.

-- Nick Coleman, nick.coleman@spglobal.com

-- Edited by Jennifer Pedrick, newsdesk@spglobal.com