North Sea Oct oil output to rise, Libya loss to prop Brent price

* Increase expected after summer maintenance period

* Brent market to remain supported by Libyan losses

* Supply set to fall about 5 percent year-on-year

By Alex Lawler

LONDON, Sept 11 (Reuters) - North Sea oil output will rise by 8.2 percent in October from September, according to loading programmes and industry sources, not enough to put much downward pressure on Brent oil prices given wider supply disruption.

A rise in North Sea supply would usually be a bearish factor for the region's crude oil differentials and Brent futures prices, although analysts said export disruptions in Libya would probably outweigh the increase.

"Under normal market conditions this would serve to weaken the market structure, particularly as it is compounded by a heavy round of October refinery maintenance," said Eugene (KOSDAQ: 023410.KQ - news) Lindell of JBC Energy, referring to higher North Sea supply.

"However, the Libyan outage is a game changer and we can expect the Brent complex to remain well supported as long as the market is deprived of the bulk of Libyan exports."

Output from 11 of the main British and Norwegian crude streams will average 1.84 million barrels per day (bpd) in October, based on loading schedules and trading sources, up from 1.70 million bpd in September.

Oil traders expect brisk demand for the October-loading North Sea cargoes, given the disruption to exports from Libya, most of whose crude is of similar quality to North Sea grades.

"The key for Europe will remain Libya. North Sea supply programmes will have a marginal impact when compared to the magnitude of the supply issue out of Libya," said Olivier Jakob of Petromatrix in Zug, Switzerland.

The main reasons for the increase are a reduced impact of oilfield maintenance and technical glitches in October, plus the addition of delayed September cargoes of Forties and Ekofisk crude into next month's total.

North Sea output usually rises in October as summer maintenance on oilfields and pipelines is completed. But supply of the same 11 crudes is set to be almost 5 percent lower than in October 2012, reflecting natural declines.

The October Brent futures contract is trading at a $1.23 a barrel premium to November (Xetra: A0Z24E - news) , reflecting a perception of tight supply in the near term, although the premium has dropped from $2.03 last week.

Much of the increase is of the crudes which underpin the Brent contract - Brent itself, Forties, Oseberg and Ekofisk (BFOE). They are expected to pump 910,000 bpd next month, versus 820,000 bpd in the latest known September programmes.

Aasgard and Stafjord supply is also set to increase, while production of Danish crude DUC, as well as Norwegian grades Gullfaks and Troll, is scheduled to be lower.

The October loading programme for Flotta, the smallest stream tracked by Reuters, has not yet emerged.

(Editing by James Jukwey)