Primrose Flow to Surface
Canada has the world’s third largest oil reserves and approximately 97 per cent of those oil reserves are located in Alberta’s oil sands. Canada’s oil sands are found in three deposits; the Athabasca, Peace River, and Cold Lake areas in Alberta and part of Saskatchewan. The greatest quantity is found in the Athabasca deposit near Fort McMurray where the oil sands are closer to the surface than in other regions.
Bitumen from oil sands is recovered using two main methods: open-pit mining and thermal in situ. The method applied depends on how deep the reserves are deposited. When bitumen is too deep (>80m) to economically mine, wells are drilled and produced through in situ methods (where heat is injected to reduce the viscosity and allow the bitumen to be pumped to surface facilities). In Alberta, 80 per cent of oil sands reserves could be recovered using in situ methods.
Primrose and Wolf Lake - Thermal In Situ
Primrose/Wolf Lake Oil Sands Project (PAW) is a thermal in situ operation located approximately 65 km north of Bonnyville and about 350 km northeast of Edmonton, primarily inside the Cold Lake Air Weapons Range. The approved project area covers 288 sections or 73,728 hectares.
The majority of bitumen produced from the PAW area is from the Clearwater Formation.
To see a diagram of the various geological formations click here.
The main process used to recover bitumen at PAW is cyclic steam stimulation (CSS) (shown below). CSS uses a single wellbore to inject steam and subsequently produce bitumen in the form of a water/bitumen emulsion. No chemicals are used.
2013 Flow to Surface
In May and June of 2013, Canadian Natural discovered four locations with bitumen emulsion at surface within PAW. At one of the locations described as site 9-21, the flow to surface occurred below a small, unnamed water body. The other three sites, 2-22, 10-1, and 10-2 are terrestrial sites.
Canadian Natural has fully cleaned up the flow to surface sites and, on April 1, 2015, we submitted an extensive technical review into the cause of the flow to surface events to the Alberta Energy Regulator (AER). The AER released a final report on March 21, 2016 which is consistent with Canadian Natural’s findings. More details about Canadian Natural’s Final Report are available here.
As a result of extensive data gathering, investigation, analytical analysis and interpretation, Canadian Natural and the industry’s understanding of cyclic steam processes has been enhanced. These learnings have been applied, and our operational practices and strategies have been modified to mitigate the risk of future seepages.
Previous updates about the incident and our response are detailed here.