Futures rose as much as 1.6% in London, set for the highest close since June 10, 2015, after advancing 2% Monday. It will take about two weeks to repair the small hairline crack after it was discovered on the North Sea Forties Pipeline System during a routine inspection, according to operator Ineos. In the U.S., crude stockpiles are forecast to drop a fourth week, a Bloomberg survey showed before government data Wednesday.

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Oil is heading for a second yearly gain as the Organization of Petroleum Exporting Countries and its allies including Russia extend supply cuts through to the end of 2018. A strategy to exit the deal can be drafted in June if the market is no longer oversupplied by then, according to United Arab Emirates Energy Minister Suhail Al Mazrouei.

“Yesterday’s closure of the Forties pipeline system for weeks is one of the most significant unplanned crude oil shortages we have seen this year,” said Tamas Varga, an analyst at PVM Oil Associates Ltd. in London.

Brent for February settlement rose as much as $1.01 to $65.70 a barrel on the London-based ICE Futures Europe exchange, and was at $65.26 at 10:07 a.m. London time. Prices gained $1.29 to $64.69 on Monday. The benchmark traded at a premium of $6.91 to February West Texas Intermediate.

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WTI for January delivery climbed as much as 57 cents, or 1%, to $58.56 a barrel on the New York Mercantile Exchange after rising 1.1% Monday. Total volume traded was about 45% above the 100-day average.

The supplies that flow through the Forties Pipeline System are the single largest constituent part of so-called Dated Brent crude that helps to settle more than half of the world’s physical oil prices. The shutdown forced Apache (APA) to suspend operations at its nearby Forties field.