Agreement DE-FC26-02NT15342, Seismic Evaluation of ...

vertical and 1500 m in the horizontal direction. The white color facies represents sands
in which different fluids were saturated. The black facies represent shales, light gray
deposits represent inter-bedded sands and dark gray deposits are channel sands. The
model input parameters, such as velocity and density, can be found in Appendix E.
Velocities were calibrated to Vp/Vs ratios to yield more accurate results. The first
forward model with constant background velocity can be seen in figure 103. This figure
shows the four fluid cases for the model. The reservoir tops are marked in green. A well
is marked on each profile at 300 m; that is the well that was used for AVO modeling. The
results of this model are similar to the first and show that the distal inter-beds of the levee
overbank are invisible when brine saturated, while there is a slight change in amplitude
where channel fill sands occur. When the inter-bedded sands are saturated with
hydrocarbons, the seismic amplitude changes significantly and there is a slight
convergence or wedge shape that occurs as the model increases in shale sediments at
distal levee overbank locations. With the complex Ursa log background in Figure 104. A
similar response can be seen of the complex seismic synthetic signature, but the fluid
response becomes more difficult to identify. The AVO response of each interval can be
seen in Figure 105. In this figure, pseudo wells at 300 m for the respective fluids are
shown, the wavelet convolved trace and the extracted synthetic trace are shown, and also
the Zoeppritz modeled AVO gathers are shown. The synthetic response shows a neutral
brine signature, while the 0% and 50% gas amplitude increases with offset are higher
than for oil. These model responses were compared the actual Upper reservoir AVO
response.
Agreement DE-FC26-02NT15342, Seismic Evaluation of Hydrocarbon Saturation 120