UPDATE 9-Oil prices up slightly on pipeline outage support

* IEA joins OPEC, EIA, raises forecast for U.S. 2018 output growth

* Ineos declares force majeure on Forties loadings

* U.S. seen driving global oil output growth to 2025 (Adds quotes, closing prices, context)

NEW YORK, Dec 14 (Reuters) - Oil prices rose almost 1 percent on Thursday after a pipeline outage in Britain continued to support prices despite data expecting a global crude surplus in the beginning of next year.

U.S. West Texas Intermediate futures settled up 44 cents, or 0.8 percent, to $57.04 a barrel.

Brent crude futures settled at $62.44 a barrel, the same settlement as Wednesday.

Prices have been supported by an outage on the Forties crude pipeline that was expected to last several weeks. Operator Ineos declared force majeure on crude oil, gas and condensate deliveries from the pipeline, a source familiar with the matter told Reuters on Wednesday.

"At present you cant ignore the impact of the Forties pipeline outage," said John Kilduff, partner at Again Capital Llc in New York, "Its a significant amount of oil that the market is going to miss and is missing. And its almost surprising its not generating more support."

A reformer was shut on Thursday after a fire in the East Plant at Citgo Petroleum Corp's 157,500-bpd Corpus Christi, Texas, refinery, said sources familiar with plant operations.

"Today you have the Texas refinery fire helping to support gasoline prices which has been the weak link in the complex," said Kilduff. "Strength in the gasoline price can be more than enough to support the crude price."

The Paris-based International Energy Agency (IEA) expects the oil market to have a surplus of 200,000 barrels per day (bpd) in the first half of next year before reverting to a deficit of about 200,000 bpd in the second half. That means 2018 overall should show "a closely balanced market."

The IEA said U.S. crude output next year would increase by 870,000 barrels per day, up from its November forecast of 790,000 bpd.

With cash pouring into the U.S. shale oil industry, the United States is on track to deliver up to 80 percent of the world's oil production gains through 2025, the IEA estimates .

Yet after lows of $56.09 earlier in the day for U.S. crude and $62.01 for Brent crude, both grades had rallied again by settlement.

"The market seems to have digested (the IEA report) and is turning its attention to the fact that were beginning to tighten," said Gene McGillian, director of market research at Tradition Energy.

A fall in U.S. crude inventories last week also lent some support. Stocks fell by 5.1 million barrels in the week to Dec. 8, the fourth consecutive week of decline, to 442.99 million barrels, the lowest since October 2015.

The front month of the U.S. crude curve for February and March remains in backwardation. Crude backwardation, in which the futures contract trades below the crude oils expected spot price at the contracts maturity, is an indicator of a tight market.

(Additional reporting by Ahmad Ghaddar in London, Henning Gloystein in Singapore; Editing by Jonathan Oatis and Alistair Bell)