Geology Reference
In-Depth Information
100ms
A
I
=
Figure 7.24
A DHI associated with an oil-bearing reservoir. Unfortunately, the reservoir has very low permeability. The presence of a DHI is no
guarantee of producibility. Data is provided courtesy of WesternGeco.
A
I
A
I
a)
Top reservoir
=
=
Top reservoir
GOC
OWC
Contact
Base reservoir
b)
Figure 7.26
Hydrocarbon contact model in a grainstone
carbonate reservoir. Contact effects are relatively subtle, with the
main DHI being a dimming of the top reservoir reflector.
It is usually the case that seismic models predict a
hydrocarbon contact will have increasing amplitude
with offset. This may not always be the case in real
data, particularly if there are problems in imaging the
far offsets.
Figure 7.27
illustrates a comparison
between a real gather (
Fig. 7.27a
) and a modelled
Figure 7.25
Oil water contact model in section of thin-bedded
sands and shales; (a) angle stack (
θ
¼ 30°) showing contact as a
series of reflection segments with slight inclination, (b) porosity
section - orange colours indicate sand layers with greater than 20%
porosity.
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