Toe-to-heel air injection | Image courtesy of Petrobank
Since the 1990s in situ operations have relied heavily on steam-assisted gravity drainage (SAGD) for bitumen extraction in the Athabasca oil sands. In the
Cold Lake and Peace River oil sands areas, cyclic steam stimulation (CSS) also has its niche. Across the regions, in situ extraction is projected to
surpass mining as the primary source of bitumen production by 2016, according to the Canadian Association of Petroleum Producers, and SAGD operations and
CSS, to a lesser extent, are set to lead the industry to that milestone.
However, other technologies, including toe-to-heel air injection (THAI™), combustion overhead gravity drainage (COGD) and enhanced solvent extraction are
increasingly ready to break new ground. Each of these processes was developed by Calgary-based organizations and each claims to offer economic,
environmental or operational improvements over more traditional insitu extraction technologies.
All three technologies rely on heat to help make the bitumen sufficiently mobile to bring it to surface. But they differ in the methods they use to heat
the reservoirs and the amount of heat required to recover the bitumen.
Combustion overhead gravity drainage (COGD) | Image courtesy of Excelsior Energy