(Adds market reaction)
Oct 30 (Reuters) - TC Energy Corp said on Wednesday it was shutting its Keystone crude pipeline after a late Tuesday oil spill in North Dakota.
The company detected a drop in pressure on Tuesday night on its 590,000-barrel-per-day (bpd) Keystone oil pipeline system from Canada, it said in a statement, without specifying the exact impact on operations.
"TC Energy immediately began the process to shut down the pipeline, activated its emergency response procedures and dispatched ground technicians to assess the situation," the company said. It did not say if the entire route of the line was closed, or just a section of the pipe.
It was unclear how much crude oil escaped in the incident about three miles (5 km) northwest of Edinburg, North Dakota, according to Brent Nelson, Walsh County emergency manager.
It was also not immediately known what the crude leak might have contaminated. The North Dakota Department of Environmental quality was en route to the scene to help oversee the cleanup and investigation of the spill, said Karl Rockman, director of the department's division of water quality.
Cleanup work was underway near the company's facilities in Edinburg, and roads were closed in the area, TC Energy said.
The pipeline system is a key transporter of Canadian crude from northern Alberta to refineries in the U.S. Midwest.
Canada heavy crude differentials widened slightly on the news, according to Net Energy Exchange. Volumes, however, were thin as the market is outside the monthly Canadian crude trading window.
Western Canada Select (WCS) heavy blend crude for November delivery last traded at $17.15 per barrel below U.S. oil futures, widening from $17.05 per barrel below WTI on Tuesday. December WCS last traded at $16.95 a barrel under, widening from Tuesday's settle of $16.75 a barrel below WTI.
In the U.S. market, the November/December WTI cash roll, which allows traders to roll contracts to the next month, firmed on the outage, traders said. (Reporting by K. Sathya Narayanan in Bengaluru and Rod Nickel in Winnipeg; Additional reporting by Nia Williams in Calgary and Devika Krishna Kumar in New York; writing by Laila Kearney in New York; Editing by Sandra Maler, Marguerita Choy and Tom Brown)