Steam Assisted Gravity Drainage Refinement
Steam assisted gravity drainage (SAGD) was introduced in the early 1980s
as a process for extracting bitumen from the oilsands. Two horizontal
pipes are drilled into the reservoir parallel to each other. Steam is
injected into the top pipe, heating the bitumen so that it becomes less
viscous and drains into the lower pipe where it is pumped to the surface
to be refined.
SAGD proved to be an effective way of extracting oil, but the method
requires large amounts of energy and water and can be a major source of
greenhouse emissions. Recently, companies have been forced to look for
ways to improve their efficiency.
Dr. Tawfik Nasr of the Alberta
Research Council (ARC) holds several patents for inventions that are
designed to reduce SAGDs energy and water consumption by means of
adding a solvent to the steam injection. The steam-solvent combination
causes more bitumen to drain into the well and uses up to half as much
water, reducing both energy requirements and greenhouse emissions. The
use of the steam-solvent combination has yielded a 19 percent increase
in oil production over the standard SAGD, and the product is less
viscous and easier to transport.
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