TC Energy Corp’s Keystone oil pipeline, which transports heavy Canadian crude to the U.S. Midwest and Gulf Coast, partially shut Thursday, sending oil futures higher in post-settlement trading. 

Pressure dropped on a segment of the line running from Hardisty, Canada, to Steele City, Neb., according to a Wood Mackenzie report seen by Bloomberg. The pressure drop indicates the line stopped moving oil. 

TC Energy and Wood Mackenzie didn’t immediately return requests for comment. 

Keystone has a long history of ruptures, including a 12,000-barrel spill last December that shut the line for two weeks and roiled global oil markets. U.S. benchmark crude futures edged above US$79 a barrel Thursday afternoon after closing at $78.93.

The shutdown at Steele City means that the line is likely sending less oil to the key storage hub of Cushing, Oklahoma, and to the refining center around Patoka, Illinois. The Keystone pipeline also ties in with the Marketlink pipeline, which transports oil to refiners on the Gulf Coast and to sea terminals that take Canadian oil to fuelmakers in Asia and Europe.