The bitumen lines between Suncor and Syncrude, and the outage playbook they make possible.
Field guide entry · written September 23, 2026.
Two bi-directional pipelines connect the Suncor and Syncrude complexes, in service since around 2020/21. They move bitumen, not synthetic crude: raw mined bitumen can flow either way between Syncrude's Mildred Lake and Aurora mines and Suncor's Base upgrader, and the reverse. They are generally described as Suncor-Syncrude interconnects; the companies have not published a separate ownership split for the lines themselves.
The documented case is the Syncrude coker outage in the first quarter of 2026. With Syncrude's upgrader constrained, about 16.4 kb/d of Syncrude bitumen flowed to Suncor's Base upgrader, and about 66.9 kb/d of Fort Hills bitumen was redirected to Base as well. Base ran at 108 percent utilization. The telling detail: Suncor's non-upgraded bitumen, the barrels sold as dilbit, ROSE during the outage, to 279.5 kb/d, which the company attributed primarily to decreased upgrader availability.
When an upgrader trips at an interconnected site, three things happen at once. First, the mine dials back, but only partially: in Suncor/Syncrude upgrader-only outages the mine typically gives up 30 to 60 percent of the SCO rate, not the full amount. Second, the balance of the bitumen redirects through the interconnect to the other site's upgrader, which shows up as a partial SCO offset. Third, flexible barrels tilt toward dilbit: Firebag and Fort Hills can swing between upgrader feed and dilbit sales, and they tilt to dilbit when upgrading capacity is short. The net effect on marketable dilbit is ambiguous every time, which is exactly why the grade layer exists.
Horizon and Scotford have no documented third-party interconnects. When their upgraders go down, the mines dial back in lockstep: Horizon turnarounds typically cut both lines 45 to 55 percent. Across 11 documented integrated-site events from 2022 to 2026, the mine dropped alongside the upgrader every single time. There is no counterexample on record.
Dilbit supply can RISE during an upgrader outage. Anyone modeling an outage as a straight subtraction of SCO from supply is missing the redirect and the dilbit tilt, and will get the heavy barrel wrong.
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