1. Seismic Response What causes a seismic response?
1. Changes in bulk-rock velocity or density
Lithology (e.g., sandstone, shale, limestone, salt)
Porosity (e.g., intrinsic, compaction, diagenesis)
Mineralogy (e.g., calcite vs. dolomite, carbonaceous shales)
Slide 6
Velocity and density are also affected by the type and density of the pore fluid
For example, assume we have a cubic meter of rock with a porosity of 30%
Let’s also assume that the density of the solid matrix is equal 2.65 g/m3
If the pore spaces of the rock were filled with salt water, the bulk density would be g/m3
However, if the pore spaces were filled with methane, the bulk density would only be g/m3
Fluid type and saturation (water, oil, gas)
Sandstone with 30% Porosity:
Pore Fluid Density
Salt Water
Fresh Water
Oil
Gas
Courtesy of ExxonMobil
L Seismic Attributes