Oil fell for a second day on Wednesday as Enbridge prepared to restart the biggest Canada-US crude pipeline, raising expectations of a short-lived shutdown that would limit the drainage of record-high inventories.

US crude for October fell 65 cents to $76.15 a barrel by 0300 GMT, a steeper drop than the 26 cent decline in the European marker ICE Brent to $78.90, because of the localised impact of the pipeline outage.

Enbridge said Tuesday it was near to completing repairs on the duct and might be able to restart the line without submitting to a lengthy formal approval process from US regulators. A report signalled the restart may come by the end of the week.

"This situation has been priced in, so now that it is going to restart earlier than expected, prices have re-adjusted, causing the prompt WTI price to weaken much more than Brent," said Serene Lim, a Singapore-based oil analyst at ANZ.

The premium of front-month Brent over West Texas Intermediate (WTI), the US benchmark priced at the Cushing storage hub in Oklahoma, widened to about $2.75 a barrel on Wednesday after narrowing to less than $1.40 earlier this week.

It was wider than $3.50 a week ago, before the pipeline halted flows.

Enbridge said it was welding a stretch of new pipe to replace a leaky area of Line 6A it removed from the ground on Monday. The line could be fixed by late Tuesday if X-rays showed the seams were secure.

Inventories rise

US crude inventories unexpectedly rose by 3.3 million barrels in the week to Sept. 10, which included at least one day of the Enbridge shutdown, as imports increased, the American Petroleum Institute (API) said on Tuesday.

The API last week reported that crude stocks had fallen a massive 7.3 million barrels in the week to Sept. 3 to 354.2 million barrels, but on Tuesday revised the week-ago figure to 358.5 million. Coupled with the latest gain, inventories are now almost unchanged from two weeks ago.

"The API did some revisions, so in itself it's not such a bearish report," Lim said. "Distillates and gasoline fell."

Gasoline stocks dropped by 963,000 barrels, versus forecasts for a 700,000-barrel drop, the API said. Distillates including heating oil and diesel fell by 1.5 million barrels, against predictions for a 300,000-barrel gain.

Government data from the Energy Information Administration, due on Wednesday at 1430 GMT, is expected to show US crude stocks fell 2.2 million barrels last week.

This week's inventory reports include data through Sept. 10, the day after a leak forced the shutdown of Enbridge's 670,000 barrel-per-day 6A pipeline, which carries Canadian crude oil to US refineries in the Midwest and the Cushing hub.

"Now that Enbridge may be restarting next week, that situation seems to be over and investors might be shifting their focus to macroenomic news," Lim said.

The oil market's attention was also set to turn to US industrial production data due later on Wednesday.

Japan intervened in foreign exchange markets for the first time in six years on Wednesday to stem economic damage from the surging yen, pushing its currency 2 per cent lower and boosting Tokyo stocks.

A trio of potentially dangerous storms swirled over the Atlantic Basin on Tuesday as Tropical Storm Karl formed in the Caribbean on a path that could take it over oil-production facilities in Mexico's Bay of Campeche. – Reuters