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crude will flow from the reservoir. In other areas, such as Canada,
the reservoir temperature is lower, and steam injection must be
used to stimulate flow form the formation.
When reaching the surface, the crude must be mixed with a
diluent (often LPGs) to allow it to flow in pipelines. The crude
must be upgraded in a processing plant to make lighter SynCrude
with a higher yield of high value fuels. Typical Syn Crude have an
API of 26-30. The diluent is recycled by separating it out and
piped back to the wellhead site. The crude undergoes several
stages of hydrocracking and coking to form lighter hydrocarbons
and remove coke. It is often rich in sulfur (sour crude) which must
be removed.

Tar sands
Tar sands can be often strip mined. Typically two tons of
tar sand will yield one barrel of oil. A typical tar sand contains
sand grains with a water envelope, covered by a bitumen film that
may contain 70% oil. Various fine particles can be suspended in
the water and bitumen.
This type of tar sand can be processed with water
extraction. Hot water is added to the sand, and the resulting slurry
is piped to the extraction plant where it is agitated and the oil
skimmed from the top. Provided that the water chemistry is
appropriate (adjusted with chemical additives), it allows bitumen
to separate from sand and clay. The combination of hot water and
agitation releases bitumen from the oil sand, and allows small air
bubbles to attach to the bitumen droplets. The bitumen froth floats
to the top of separation vessels, and is further treated to remove
residual water and fine solids. It can then be transported and
processed the same way as for extra heavy crude.
It is estimated that around 80% of the tar sands are too far
below the surface for the current open-pit mining technique.
Techniques are being developed to extract the oil below the
surface. These techniques requires a massive injection of steam
into a deposit, thus liberating the bitumen underground, and
channeling it to extraction points where it would be liquefied
before reaching the surface. The tar sands of Canada (Alberta) and

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