TC Energy Corp. restarted the ruptured segment of its Keystone oil pipeline, following a spill that forced the conduit shut for more than three weeks.

“After completing repairs, inspections and testing we proceeded with a controlled restart of the Cushing Extension,” the company said in a statement. “The Keystone Pipeline System is now operational to all delivery points.”

The massive crude pipeline, which can carry more than 600,000 barrels a day, is a major conduit linking oil fields in Canada to refiners in the U.S. Gulf Coast. A leak on a section of the pipeline that extends to the Cushing, Okla., storage hub spilled 14,000 barrels of oil in Kansas in early December, becoming one of the largest onshore US oil spills since 2010, according to government data.

Two other legs of the line — one to Patoka, Ill., and one from Cushing to the Gulf — are also operating at reduced rates.