TransCanada Corp has told some customers that it will cut deliveries by 85 per cent or more on its 590,000-barrel-per-day Keystone crude pipeline through to the end of November, according to three sources familiar with the matter. 

The line, which links Alberta's oil sands to U.S. refineries, was shut last week after a 5,000-barrel spill in South Dakota.

Some customers have received higher cuts depending on commitment levels, one of the sources said.

A company official could not immediately be reached for comment.

Transcanada in an earlier statement said that over 160 workers were on the site of the spill and more than 16,000 gallons had been removed as of Nov. 21.

"Repair plans will be confirmed once we are able to safely expose the impacted section of pipe," the company said.

The prompt WTI spread was trading up 4 cents at 10.22 p.m. EST, the first time it's been in positive territory since November, 2014, with traders citing expectations of larger draws from Cushing, Oklahoma, the delivery point of the U.S. crude futures contract.

The Keystone pipeline carries crude into Cushing.