Geology Reference
In-Depth Information
a)
Gas Well
b)
Note thickness variation
in apparent isochore
Effective Angle
+
GWC
2.0
Brine sand
Sin
2
θ
Gas sand
-
Bright peak
dominated by
contact reflection
Migrated stack
Figure 7.11
A Class IIp gas sand; (a) migrated full stack section (after Rutherford and Williams,
1989
), (b) notional AVO model explaining the
bright peak associated with the gas water contact and the lack of a reflection at the top of the sand.
a)
Near 210-1800m
Figure 7.12
A Class IIp oil sand; (a) near
stack section, (b) far stack section, (c)
gather showing the phase reversal at the
top of the reservoir.
c)
offset
Top
reservoir
Far 1960-3710m
b)
sub-cropping lithologies. However, the reservoir
section can be seen to generally brighten in response
to the lowering of sand impedance. In these types of
multi-layered scenarios the brightening is typically
associated with thin-bed couplet reflections, sand
base/top or top/base depending on the relative thick-
ness and impedances of porous and non-porous units.
Figure 7.19
shows an example from an aeolian
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