* Dec WCS trades at $41.25/bbl below WTI
* Dec synthetic trades at $15.25/bbl below WTI
CALGARY, Alberta, Nov 5 (Reuters) - Canadian heavy crudeprices extended losses on Tuesday to hit fresh 10-month lows, ascongestion on export pipelines and unplanned refinery outagesweighed on the market.
Western Canada Select heavy blend for December delivery lasttraded at $41.25 per barrel below the West Texas Intermediatebenchmark, according to Shorcan Energy brokers - the widestdifferential since January - compared with a settlement price onMonday of $40.90 per barrel below the benchmark.
Increased pipeline apportionment on the Enbridge Inc network means producers are unable to ship as muchcrude as they want to market and oil is getting bottlenecked inAlberta, driving prices downward.
Reduced demand from Citgo Petroleum Corp's 174,500 bpd Lemont, Illinois, refinery after a fire in October,added to pressure on heavy crude prices. Trade sources saidthere was a separate fire over the weekend at the 130,000 bpdCo-op refinery in Regina, Saskatchewan.
But a Calgary crude trader said the impact of the Co-oprefinery fire on December differentials was limited, given thealready steep discount to WTI.
"It was already a mess. This just adds onto the pile," hesaid.
Light synthetic crude from the oil sands for Decemberdelivery edged slightly higher to trade at $15.25 per barrelbelow WTI. It held within sight of Monday's settlement of $15.50per barrel below the benchmark, the widest differential sinceMarch 2012.