A new report by Canadian Natural Resources Limited admits that the company's practice of high-pressure steaming may have contributed to a large oil spill that released over 12,000 barrels of bitumen for 14 months near Cold Lake, in northern Alberta. CNRL's recent admission is at odds with its previous claim that the bitumen spill was caused by flaws in legacy wellbores.

The report said steaming operations are conducted within the oil sands of the Clearwater reservoir. The company injects steam deep underground to soften and melt the bitumen so that it can be brought to the surface in a method called high pressure cyclic steam stimulation. Another cause for the ongoing leaks could be “vertical hydraulic induced fractures”, which are cracks in the deeper rock layers or in the top layers of shale caused by steam pressure. A regulator report in 2009 had highlighted possible weak geological rock formations in the area, though the company denied that it was a relevant factor for the Cold Lake spill. 

Image from CNRL site

In April, the Alberta Energy Regulator gave approval for CNRL to resume steaming in the area, provided that the steaming is not done within one kilometre of the leaking sites. Environmental advocates denounced the decision at the time, saying that steaming permits should not be given prior to finding out the root cause of the ongoing leaks near Cold Lake. 

Asked if the latest report from CNRL would have any impact on the steaming permit, AER spokesperson Bob Curran it would not, because of the one kilometre distance between the steaming activities and the leaks. 

As for how CNRL's findings might affect other companies, he said it was "still under investigation". 

The oil spill, which was initially discovered in early 2013, was described by the company as "totally solvable" last November. But the spill is still ongoing, and does not appear to be slowing down.

CNRL Cold Lake spill causation report