Last checked at 
* Nov WCS trades at $30.60/bbl below WTI
* Nov synthetic trades at $9.90/bbl below WTI
CALGARY, Alberta, Oct 9 (Reuters) - Canadian heavy crudeprices strengthened slightly on Wednesday, although gains weremarginal as supply from the oil sands continued to outpacerefinery demand.
Western Canada Select heavy blend for November delivery lasttraded at $30.60 per barrel below the West Texas Intermediatebenchmark, according to Shorcan Energy brokers.
That compares with a settlement price of $32.25 per barrelon Tuesday.
Canadian crude prices traditionally weaken during therefinery maintenance season in the autumn and increasing volumesfrom Imperial Oil's Kearl mining project in northern Albertahave been adding to pressure on prices.
Cenovus Energy Inc is also ramping up production atits 110,000 bpd Foster Creek oil sands project followingscheduled maintenance that began in late September.
Meanwhile, repairs at BP Plc's 405,000 barrel per dayWhiting, Indiana, refinery, are slowing down a $4-billion revampthat will enable the refinery to run more heavy Canadian crude.
Traders in Calgary said although there was limited scope forbig near-term gains, differentials were likely to narrow in thecoming quarter as refinery demand improved.
"People are trying to get through this. As soon as Whitinggets going they will start clearing the market," one crudetrader said.
Light synthetic crude from the oil sands for Novemberdelivery last traded at $9.90 per barrel below WTI, comparedwith a settlement price of $10.90 per barrel below the benchmarkon Tuesday.
Synthetic grades have recovered slightly after tradingaround $12.60 per barrel below WTI earlier this week, the widestdifferential since the first quarter of 2012.
Rising production from Syncrude's oil sands project innorthern Alberta has pushed synthetic prices sharply lower sincethe summer. Market sources said some buyers thought the selloffwas overdone, even though supply is expected to remain strong.
