Invention of Steam Assisted Gravity Drainage
Canada’s Oil Sands: Invention of Steam Assisted Gravity Drainage
Canada has some of the largest oil reserves in the world, second only to Saudi Arabia. However, this oil is in the form of bitumen mixed with sand, clay, water and other minerals. Extracting and refining this form of oil in an efficient way required the innovation of Roger Butler.
Butler was born in the UK, but came to Canada in 1951 to take a post as a professor of chemical engineering at Queen’s University in Kingston, Ontario. In 1955 he went to work for Imperial Oil where, during the 1970s, he developed the technique of steam assisted gravity drainage (SAGD).
The SAGD process uses directional drilling to place two horizontal wells in parallel, with one approximately five meters above the other. Steam is injected into the top well, which heats up the heavy crude oil or bitumen in the vicinity. Due to the increase in temperature, viscosity of the heavy crude oil decreases and, with the help of gravitational forces, allows the material to seep downward into the lower well. The recovered extract can then be directed back up toward the surface using pumps designed for materials with high viscosity. SAGD allows for crude oil to be extracted in situ and makes it possible for crude oil to be extracted from deeper deposits. It also has a greatly reduced footprint compared to open pit mining, and does not require tailings ponds.
In 1980, Butler oversaw the creation of the first SAGD test facility in Cold Lake, Alberta. Today, 80% of oil sands operations use some variation on the SAGD process, and the technology has been adopted internationally for crude oil production. Moreover, SAGD is being continually improved to increase efficiency in the amount of crude oil produced per unit of steam. Although Butler passed away in 2005, his technology has helped establish our country as a world leader in energy production.