Total oil imports for Canada are around 700,000 bbl/day.  Of that, somewhere around 400,000 bbl/day are imported to Atlantic refineries (most of which is refined and exported to the US).  Quebec has a refining capacity of less than 400,000 bbl/day, and with reversal of line 9, pipeline capacity of 300,000 bbl/day.  Almost all the oil refined in Ontario is via pipeline from western Canada.  So why do you think there are a million barrels of oil being shipped down the St. Lawrence every day?