|SAGD employs two horizontal wells: one injection well (upper well) through which the high pressure steam is continuously injected and one production well (lower well) into which the softened bitumen continuously flows from which it can be pumped to the surface.
The original SAGD wells were drilled horizontally from a tunnel accessed with vertical mine shafts. The development of directional drilling techniques that allowed companies to drill horizontal wells accurately, cheaply and efficiently was key to the current success of SAGD technology. With the lower cost of drilling accurately spaced horizontal well pairs, and the very high recovery rates of the SAGD process, SAGD is an economically attractive recovery technique.
SAGD technology is being applied at a number of oil sands projects including EnCana’s Foster Creek and Christina Lake projects, Nexen’s Long Lake project and Suncor’s Firebag project.