Table 2 indicates that the hot oil zone is characterized
by a pore pressure increase of about 75 psia, a temperature increase of
about 75 F, and a reduction of gas saturation to about 0%,
compared to ambient reservoir conditions. The pore pressure increase
results in Vp decrease of 5% at most. The temperature increase
in mixed oil/water saturated cores results in a Vp decrease of about
10-15%, as shown in Figure Vptemp.
The reduction of the
gas saturation from an initial 10% to a final 0% may result
in a Vp increase as large as 20-25%. Combining these effects,
the net change in velocity at the hot oil zone may be negligible,
compared to initial reservoir conditions.
Since the density change is also negligible, the hot oil zone
may be seismically transparent.