NORTH AMERICAN OIL SANDS: HISTORY OF DEVELOPMENT, PROSPECTS FOR THE FUTURE - Energy Research Developments: Tidal Energy, Energy Efficiency and Solar Energy - page 298

But a relatively new technology — steam-assisted gravity drainage (SAGD) — has
demonstrated that its operations can recover as much as 70% of the bitumen inplace. Using
SAGD, steam is added to the oil sands using a horizontal well, then the liquefied bitumen is
pumped simultaneously using another horizontal well located below the steam injection well
(see figure 4). The SAGD process has a recovery advantage over the CSS process, which only
recovers 25%-30% of the natural bitumen. Also, the lower steam to oil ratio (the
measurement of the volume of steam required to extract the bitumen) of SAGD results in a
more efficient process that uses less natural gas.[42] SAGD operations are limited to thick,
clean sand reservoirs, but it is reported by the industry that most of the new in-situ projects
will use SAGD technology.[43] A number of enhanced SAGD methods are being tested by
the Alberta Research Council. They could lead to increased recovery rates, greater efficiency,
and reduced water requirements.
The emerging Vapor Extraction Process (VAPEX) technology operates similarly to
SAGD. But instead of steam, ethane, butane, or propane is injected into the reservoir to
mobilize the hydrocarbons towards the production well. This process eliminates the cost of
steam generators and natural gas. This method requires no water and processing or recycling
and is 25% lower in capital costs than the SAGD process. Operating costs are half that of the
SAGD process.[44]
A fourth technique is cold production, suitable for oil sands lighter than those recovered
using thermal assisted methods or mining. This process involves the coproduction of sand
with the bitumen and allows the oil sands to flow to the well bore without heat. Imperial Oil
uses this process at its Cold Lake site. Oil sand produced using in-situ techniques is sold as
natural bitumen blended with a diluent for pipeline transport.
Source : Oi l Sands Technology Roadmap, p. 41.
Figure 5. Upgrading to SCO.