Abstract: Geology of Heavy-Oil Deposit at Cold Lake, Alberta

Donald B. Harrison

More than 900 billion bbl of heavy oil are present in the Western Canadian heavy-oil belt. Of this reserve over 100 billion bbl is at Cold Lake in Alberta. Low-gravity viscous oil at Cold Lake is in Lower Cretaceous clastic sequences which are several hundred feet thick and buried to an average depth of 1,000 ft (300 m). Variations in the amount and type of sediment supply combined with moderate structure have resulted in several different reservoir configurations. Four recognizable formations, the McMurray, Clearwater, and Lower and Upper Grand Rapids, are identified in the oil-bearing Lower Cretaceous section. The Clearwater has the thickest and best developed sands and approximately 40% of the reserve. Sands of this formation can provide 160 ft (48 m) of oil-bearing se tion, free of underlying water, when in a structurally favorable position.

The viscosity of the oil and an accompanying lack of reservoir energy preclude conventional recovery methods in the heavy-oil deposits. Recovery is dependent on in-situ thermal-recovery schemes to mobilize the oil. The character of the Clearwater reservoir has led to the use of a steam-stimulation recovery process which heats the reservoir, reduces the viscosity, and provides an energy source to mobilize the oil.

The complex reservoirs of the heavy-oil deposits require detailed geologic interpretation to unravel not only the gross depositional characteristics but also the specific reservoir attributes that are critical in selecting and operating an effective recovery scheme.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC