A quickly expanding wildfire in northeastern Alberta has forced Canadian Natural Resources Ltd. to shut down more oil sands production, pushing total volumes offline owing to the blaze to more than 8 per cent of the province's oil output.

Canadian Natural, the country's largest independent oil producer, said on Monday it shut down 18,000 barrels a day of bitumen output at its Kirby South project near Cold Lake, Alta., leaving it producing 12,000.

That is in addition to 80,000 barrels a day the company shut off at its nearby Primrose development over the weekend.

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Cenovus Energy Inc., meanwhile, suspended its Foster Creek steam-driven oil sands development, a joint venture with ConocoPhillips that was producing 135,000 barrels a day.

There are no reports of facilities being damaged. However, road access has been cut off and the companies have evacuated hundreds of workers.

The forest fire ravaging the Cold Lake Air Weapons Range, a military training ground where several oil projects are located, has more than doubled in size over the past two days and is now estimated at more than 8,200 hectares. That is despite the efforts of more than 200 firefighters, according to the Alberta government.

It is one of 29 wildfires burning in the province. A 200-hectare blaze forced about 2,000 people from their homes in the Wabasca, Alta., area, 325 kilometres north of Edmonton, late Sunday.

The oil companies said that they do not expect the outages to cause long-term damage to their equipment or underground bitumen reservoirs, which they heat with steam to allow the gooey crude to flow to the surface in wells.

"We take down our facilities at various times in a controlled fashion such as this to conduct maintenance. We have stopped steam production and our wells are currently offline," Cenovus spokesman Reg Curren said. "We can't speculate on the exact length of time it would take for the reservoir to be impacted by the shutdown, but it would be considerably longer than we anticipate the fire will impact operations."

One of the largest oil sands projects in the area, Imperial Oil Ltd.'s Cold Lake development, is still operating, though the company is monitoring the fire situation closely, spokesman Pius Rolheiser said.

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Devon Energy Corp.'s Jackfish oil sands developments, located north of Foster Creek, also remain operational, spokeswoman Nadine Barber said.

The government imposed a province-wide fire ban on Monday, prohibiting all open fires in campgrounds and back-country areas, as forecasters called for hot, dry weather for at least one more week.