* WCS quoted at $26/bbl under WTI
* Light synthetic quoted at $5.50/bbl under WTI
* Wood River, Illinois, refinery still undergoing upkeep
CALGARY, Alberta, Nov 12 (Reuters) - Canadian cash crude oil prices strengthened on Monday as last week's the fears of tight U.S. Midwest pipeline capacity eased somewhat, trade sources said.
Western Canada Select heavy blend for December delivery was last quoted at $26 a barrel under benchmark West Texas Intermediate, compared with $26.90 a barrel under on Friday, according to Shorcan Energy Brokers.
The WCS spread has tightened by $4.75 a barrel in the last week.
December light synthetic, derived from the Alberta oil sands, fetched $5.50 a barrel under WTI, up 35 cents a barrel.
Canadian crude prices slumped early this month after Enbridge Inc apportioned many of its U.S. Midwest pipelines and TransCanada Corp's Keystone oil pipeline to Illinois and Oklahoma had an unplanned five-day outage.
But in recent days, "panic subsided," one market participant said.
Adding to demand, a major buyer of Canadian crude, the 306,000 barrel-a-day Wood River, Illinois, refinery, owned by Phillips 66 and Cenovus Energy Inc, is expected to soon ramp up production following a turnaround that started in October.
However, the maintenance was still under way on Monday, Phillips 66 said.