The background values and the geometry of the reservoir model are plotted in Figure . The reservoir is 50 m thick and the top of the reservoir is at 2 km depth. We simulate water injection wells located at 2 km and 3 km respectively. Table 1 lists the pre-flood and post-flood petrophysical properties at an injection well. The background properties both above and below the reservoir are: Vp = 2.38 km/s, Vs = 1.13 km/s, and = 2.1 g/cc. The relative P impedance contrast is calculated as:
(9) |
and similarly for the relative S impedance contrast:
(10) |
where ``+'' superscripted properties refer to the layer below the interface, and ``-'' superscripted properties refer to the layer above the interface. We note that and are exactly twice the normal incidence P and S plane-wave reflection coefficients Rp and Rs:
(11) |
(12) |
Figure shows the depth-dependent form of the background model and the reservoir properties at an injection well, pre- and post-flood. Vs is the left-most curve, in the center, and Vp to the right of each panel.
3|c|Reservoir properties | ||
---|---|---|
pre-flood | post-flood | |
Vp | 2.19 | 2.29 |
Vs | 1.15 | 1.03 |
2.05 | 2.09 | |
Rp | -0.055 | -0.020 |
Rs | -0.003 | -0.050 |