CALGARY—Canadian Natural Resources Ltd., has begun restarting its Horizon oilsands plant operation in northern Alberta with a goal of returning to full operations by Thursday.
Output at Horizon has been suspended since early February when a malfunction affected the upgrader, which processes thick, sticky bitumen from the oilsands into a type of crude that refineries can handle.
The problem was linked to the fractionator, a unit that separates oil into various components.
CNQ, one of Canada’s biggest oil and natural gas producers, said the restarting process began on Tuesday.
Earlier this month, the company scaled back its output targets for the year due to the Horizon troubles. It now expects output between 93,000 and 103,000 barrels per day of synthetic crude oil from 105,000 to 115,000 barrels per day.
The company also said it would launch an independent review of its operations following the unexpected outage.
Canadian Natural has already completed its own investigation, and has an idea of what caused the problems at the upgrader.
The primary upgrading plant had been shut down for repairs in January, and in starting back up, some water that had mixed with the diluted bitumen was brought into the fractionator.
Canadian Natural initially thought the damage would be minor, but on closer inspection found it to be much more severe than expected.
The cost of repairs is expected to be $35 million.
Just over a year before the latest incident, an explosion badly damaged the 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.
Canadian Natural has 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.