Thermal In Situ Oil Sands

Thermal In Situ Oil Sands

Primrose Kirby

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Canadian Natural holds some of the best thermal in situ oil sands assets in Canada, providing tremendous value and growth potential. Our thermal assets are located in two of the major oil sands deposits in Western Canada – the Athabasca and the Cold Lake deposits. Canadian Natural's oil sands deposits are in the form of bitumen, which in its natural state is too viscous to flow. When bitumen is too deep (>80 m) to economically mine, steam is injected to warm the bitumen, reducing the viscosity and allowing it to be pumped through surface wells. Only about 7% of Canada's oil sands can be mined, the majority has to be recovered using thermal in situ recovery.

Steam Assisted Gravity Drainage (SAGD)

Canadian Natural is an industry leader, successfully implementing one of the first SAGD programs in Canada at our Wolf Lake property. SAGD wells are drilled in pairs and use continuous steam injection to mobilize bitumen. As the figure below illustrates, steam is injected into the upper well mobilizing bitumen above it which then drains down to the lower production well due to gravity. The SAGD process allows for a high bitumen recovery factor typically greater than 50%. SAGD operations require clean, continuous reservoirs and two wells resulting in a higher capital investment. This process will be the preferred production process for the McMurray formation at Canadian Natural’s Athabasca area fields.

Within the Athabasca deposits, the McMurray reservoir is our primary target and steam assisted gravity drainage (SAGD) is the recovery process of choice. SAGD uses two well bores, one for continuous steaming and the other for continuous production. Within the Athabasca region, the majority of our assets are in the planning stages, which include Grouse, Ipiatik, Gregoire and Leismer. Today, Kirby South is the Company’s largest SAGD project with production volumes near 40,000 bbl/d. The next development at Kirby, Kirby North, was reinitiated for construction and drilling in late 2017 and targets first oil in early 2020.

Cyclic Steam Stimulation (CSS)

Canadian Natural also employs cyclic steam or "huff and puff" technology to develop bitumen resources. This technology requires one well bore and the production consists of two distinct phases:

     1. Injection - Steam is injected for several weeks, mobilizing cold bitumen
     2. Production – Flow is reversed producing oil through the same well bore

The two phases together comprise one cycle. Steam is re-injected to begin a new cycle when oil production rates fall below a critical threshold due to the cooling of the reservoir.

Canadian Natural is a leader in the commercial application of horizontal well CSS illustrated in the figure below.

CSS is a robust, proven technology adaptable to thinner inter-bedded reservoirs requiring only one well bore which in comparison to SAGD results in a reduced capital investment. CSS does have a lower recovery factor than SAGD but is the preferred production process in the Clearwater formation at Canadian Natural’s Wolf Lake and Primrose (North, South, and East) fields.