Page 122 - Principles of Applied Reservoir Simulation 2E

Part II: Reservoir Simulation 107

of seismic waves occur at reflectors. A seismic reflection occurs at the interface
between two regions with different acoustic impedances.

Model
5 10 15 0 2
__ .

100ms —- < i
200 ms —
Seismic response

Figure 12-1. Seismic trace for a sand wedge (after
Ruijtenberg, 1990; reprinted by permission of the Society
of Petroleum Engineers).

Acoustic impedance is a fundamental seismic parameter. Acoustic
impedance is defined as Z = p V where p is the bulk density of the medium and
V is the compressional velocity of the wave in the medium. Figure 12-2

3.0
n 28
E
•S2 2.6
o>
2 4
'
C 2.2
0)
Q
2.0
1.8
1 . 5 2 . 0 3 4 5 6 7 8 9
Velocity (km/sec)
Figure 12-2. Seismic wave velocity and bulk density of
rock (after Telford, et al., 1976; reprinted by permission
of Cambridge University Press; after Gardner, et al.,
1974).