Geoscience Reference
In-Depth Information
Fault damage zone within aeolian sandstones, Moray Coast, Scotland
There are many ways one could classify dif-
ferent types of reservoirs, such as siliciclastic,
carbonate and fractured reservoirs. We have cho-
sen to group sandstone reservoirs by common
depositional settings, namely:
Aeolian reservoirs
Fluvial reservoirs
Tidal-deltaic reservoirs
Shallow-marine reservoirs
Deep-marine reservoirs
We then go on to consider carbonate and
structurally-controlled reservoirs as two further
types. In practice, many carbonate reservoir
systems may contain siliciclastic units, and both
sandstone and carbonate reservoirs may be signifi-
cantly influenced by the presence of faults and
fractures.
The main issue is to identify the key
characteristics of the reservoir under consider-
ation as a starting point for the reservoir model
design which will be unique to that reservoir.
6.1
Aeolian Reservoirs
Aeolian depositional environments are one of
a number of 'siliciclastic' sedimentary systems.
Siliciclastics are silicate- (typically quartz-)
dominated, clastic, sedimentary rocks, or put
more simply, sediments predominantly com-
posed of sand grains. We often use the term
clastic
as an abbreviation (slightly incorrectly
as clastics may also be carbonates) but their
main feature is the predominance of quartz sand
grains, the size of which varies enormously, from
mudstones (grains of a few
m in diameter)
to coarse-grained sands (mm sized) to
conglomerates (cm-sized grains). Contrasting
siliciclastic systems will be reviewed in the fol-
lowing five sections, starting with the most
quartz-rich:
μ
the
aeolian (wind-blown)
sand
systems.
Aeolian systems typically produce high net-
to-gross (or at least high sand fraction) reservoir
