* WCS quoted at $17.20-$17.75/bbl under WTI
* Some players caught short on outage, apportionment bets
* Synthetic $9.50-$10/bbl over WTI
CALGARY, Alberta, June 14 (Reuters) - Canadian heavy oil differentials have narrowed after some players were caught short betting on a longer Keystone pipeline outage and higher Enbridge apportionment levels, trade sources said.
In addition, a handful of U.S. Midwest and Canadian refineries resumed normal operations following outages, lifting demand.
Western Canada Select heavy blend for July delivery was quoted at $17.20-$17.75 a barrel under benchmark West Texas Intermediate, as much as $2.50 narrower than quotes from last week.
TransCanada Corp (TRP.TO) restarted the 591,000 barrel a day Keystone pipeline to Oklahoma from Alberta on June 5, a week after it was shut down for the second time in a month due to a faulty pump station fitting.
Marketers who had wagered the line would be down for a longer duration, along with those who had expected more severe space rationing on Enbridge Inc's (ENB.TO) system for June, were caught short, one trader said.
Over the past week, refineries including BP Plc's (BP.L) 405,000 bpd Whiting, Indiana, plant and Exxon Mobil Corp's (XOM.N) 238,600 bpd Joliet, Illinois, facilities were reported to have been repaired following outages of some units.
In Alberta, Suncor Energy Inc (SU.TO) restarted its 135,000 bpd Edmonton refinery and Imperial Oil Ltd (IMO.TO) wrapped up maintenance at its 187,000 bpd Strathcona plant. [ID:nWNA0700] [ID:nN14201470].
Limiting further gains are still-large storage volumes across the Enbridge system and in the North American crude-pricing hub of Cushing, Oklahoma, industry sources said.
Analysts have blamed brimming North American inventories for a deep discount on WTI versus world benchmark Brent crude. That gap hit a record $22.80 a barrel on Tuesday. [ID:nL3E7HE0CA]
July light synthetic barrels were discussed in the $9.50-$10 a barrel range over WTI, compared with $8.10-8.70 over last week.
Canadian Natural Resources Ltd (CNQ.TO) has said that the restart of its Horizon oil sands project will be delayed by more than a month due to the effects of Alberta's wildfires in May. [ID:nN31108628]
The 110,000 bpd plant has been shut down since an early January explosion and fire at the upgrading plant.
Early last month, Suncor started several weeks of maintenance on Upgrader 2 at its northern Alberta oil sands operation, which it said would reduce output by 215,000 bpd over the duration. The normal capacity is 350,000 bpd. (Reporting by Jeffrey Jones; editing by Peter Galloway)