* September WCS trading at $22.40/bbl below WTI
* September synthetic at $3.75/bbl premium to WTI
CALGARY, Alberta, Aug 14 (Reuters) - Canadian crude prices were little changed on Wednesday, with traders reporting thin volumes as the market looked ahead to news of pipeline apportionment next week.
Traders will find out whether Enbridge Inc will ration space on pipelines carrying Canadian crude to U.S. markets, in the first apportionment since regulators approved plans to change how the company calculates how much crude shippers can nominate.
High apportionment would likely push prices lower on concerns crude will get bottlenecked in Canada.
Western Canada Select heavy blend for September delivery last traded at $22.40 per barrel below the West Texas Intermediate benchmark, according to Shorcan Energy Brokers.
That compares with a settlement price of $22.80 per barrel below the benchmark on Tuesday.
Heavy crude prices have dipped in recent weeks as production from Imperial Oil's Kearl oil sands project reached the market and as traders braced for seasonal refinery maintenance in the autumn.
But Martin King, analyst at FirstEnergy Capital in Calgary, said heavy grades may start to strengthen next month as a result of BP Plc's modernization project at its 413,000 barrel per day Whiting, Indiana, refinery.
When all the units are up and running, the refinery will be able to run 80 percent heavy sour crude oil.
"Prices may start to improve once we hit September because I think there will be guidance on when the Whiting refinery is going to be ready to start taking Canadian heavy" King said.
Light synthetic crude from the oil sands for September delivery inched higher to $3.75 per barrel above WTI, from $3.65 per barrel above the benchmark on Tuesday.
Synthetic prices have been supported since June by ongoing maintenance on a coker at Syncrude's oil sands project in northern Alberta. Syncrude's month-on-month production fell by 17 percent in July to 183,000 bpd.