Canadian Natural Horizon oilsands plant down for unplanned maintenance

CALGARY - Canadian Natural Resources Ltd.'s stock fell more than four per cent Tuesday after confirming that its Horizon oilsands mine is down for repairs.

Shares in the major oil and gas producer (TSX:CNQ) closed at $38.52, a drop of $1.76.

"Horizon is currently experiencing unplanned maintenance and has temporarily curtailed production," Canadian Natural said in an emailed statement.

In releasing its third-quarter results in November, Canadian Natural said it was aiming to produce between 105,000 and 115,000 barrels of oil at Horizon in 2012.

The company said Tuesday that the outage does not change that target.

Canadian Natural did not give a cause for the shutdown nor did it say how long it was expected to last.

Just over a year ago, an explosion badly damaged an upgrader at the mine north of Fort McMurray, Alta.. Five workers were injured.

The company has attributed the fire to a valve opening at the top of a coking drum at the wrong time. Frigid temperatures in region at the time caused a great deal of freeze damage to the plant and forest fires later in the spring slowed repair work.

After shutting the mine for repairs, Horizon began churning out crude again in August.

Canadian Natural estimated repair and rebuild costs of between $400 million and $450 million but recouped much of that through insurance.

Canadian Natural is one of Canada's biggest oil and natural gas producers, with the bulk of its operations in Western Canada. It also has holdings in the U.K. portion of the North Sea and off the coast of West Africa.

In the oilsands, Canadian Natural is planning a second phase to its Horizon mine, and a new steam-driven oilsands project at Kirby, Alta.