Page 117 - Synthetic Fuels Handbook

CHAPTER 4

FUELS FROM TAR SAND
BITUMEN

Tar sand bitumen is another source of liquid fuels that is distinctly separate from conven-
tional petroleum (US Congress, 1976; Speight, 2005, 2007).
Tar sand (also called oil sand in Canada) or the more geologically correct term bitumi-
nous sand is commonly used to describe a sandstone reservoir that is impregnated with a
heavy, viscous bituminous material. Tar sand is actually a mixture of sand, water, and bitu-
men but many of the tar sand deposits in countries other than Canada lack the water layer
that is believed to facilitate the hot water recovery process. The heavy bituminous material
has a high viscosity under reservoir conditions and cannot be retrieved through a well by
conventional production techniques.
Geologically, the term tar sand is commonly used to describe a sandstone reservoir
that is impregnated with bitumen, a naturally occurring material that is solid or near solid
and is substantially immobile under reservoir conditions. The bitumen cannot be retrieved
through a well by conventional production techniques, including currently used enhanced
recovery techniques. In fact, tar sand is defined (FE-76-4) in the United States as:

The several rock types that contain an extremely viscous hydrocarbon which is not recover-
able in its natural state by conventional oil well production methods including currently used
enhanced recovery techniques. The hydrocarbon-bearing rocks are variously known as bitu-
men-rocks oil, impregnated rocks, tar sands, and rock asphalt.

In addition to this definition, there are several tests that must be carried out to deter-
mine whether or not, in the first instance, a resource is a tar sand deposit (Speight, 2007
and references cited therein). Most of all, a core taken from a tar sand deposit, the bitumen
isolated therefrom, are certainly not identifiable by the preliminary inspections (sight and
touch) alone.
In the United States, the final determinant is whether or not the material contained
therein can be recovered by primary, secondary, or tertiary (enhanced) recovery methods
(US Congress, 1976).
The relevant position of tar sand bitumen in nature is best illustrated by comparing its
position relevant to petroleum and heavy oil. Thus, petroleum is referred to generically as a
fossil energy resource and is further classified as a hydrocarbon resource and, for illustrative
(or comparative) purposes in this report, coal and oil shale kerogen have also been included in
this classification. However, the inclusion of coal and oil shale under the broad classification
of hydrocarbon resources has required (incorrectly) that the term hydrocarbon be expanded to
include these resources. It is essential to recognize that resources such as coal, oil shale kero-
gen, and tar sand bitumen contain large proportions of heteroatomic species. Heteroatomic
species are those organic constituents that contain atoms other than carbon and hydrogen, for
example, nitrogen, oxygen, sulfur, and metals (nickel and vanadium).

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