Oil sands are one of the world’s most expensive and are also among the most carbon dioxide-intensive forms of crude-oil extraction.

Canada's oil sands production will grow by 42 percent to 3.4 million barrels per day by 2025, most of which will come from the expansion of existing facilities rather than new projects

Energy companies have been hurt by the swoon in crude prices this year, but Canadian Oil Sands is among the worst performing. The company’s stock has lost almost 40% of its value so far this year, compared with a 22% decline in the Toronto Stock Exchange energy index.

Moody’s Investors Service on Monday cut the credit rating of Canadian Oil Sands Ltd. to one notch above speculative grade, citing the oil-sands producer’s “elevated leverage” as a result of lower crude oil prices.