* July Western Canada Select discount to WTI at $20.25/bbl
* July synthetic bid-ask at $4.75-4.00/bbl under WTI
CALGARY, Alberta, May 30 (Reuters) - Canadian heavy oil prices weakened on Wednesday as refinery work in Canada and the United States cut into demand.
Western Canada Select heavy blend for July delivery last traded for $20.25 per barrel below the West Texas Intermediate benchmark, compared to a settlement price of $19.50 under WTI on Tuesday, according to Shorcan Energy Brokers.
Imperial Oil Ltd continues maintenance work on its 187,000 barrel per day refinery in Edmonton, Alberta, and at its 121,000 bpd refinery in Sarnia, Ontario, both of which process Canadian crude.
As well, the 146,000 bpd Borger, Texas, refinery owned by Phillips 66 and Cenovus Energy Inc, said on Wednesday it began scheduled maintenance on a fluid catalytic cracker unit that will last until June 11.
Light synthetic crude for July had yet to trade on Wednesday. Bidders were last offering $4.75 per barrel under WTI while the last asking price was $4.00 under the benchmark, according to Shorcan. A day earlier, synthetic settled at a discount to the benchmark of $4.05 per barrel.