Why do Seismic Inversion?

Can anybody please explain to me what the advantages are of Seismic inversion? I hear people talking about it a lot, but can not find exactly what it mean. It is something to do with getting petrophysics from geophysics, ok?

thank you

Seismic inversion is used to translate seismic data into a quantative measure of certain rock properties (usually density and porosity, but also fluid/gas composition). So basically you are right...

You ask why we do it... well that's because interpreting seismic and using it to follow horizons is one thing but getting actual rock properties from it is much more valuable. A quantative link between the seismic signal and the rock physics is needed to make sure we understand the meaning of the seismic signal and use it to it's full potential. Then, when we understand this link we can avoid ambiguities in seismic interpretation, including fluid-lithology, sand-shale, and porosity-saturation ambiguities. Through this we can make more accurate predictions into reservoir quality and can actually extrapolate away from the wells using the seismic reflector data. Usually the seismic signal is calibrated with the well log data (sonic, density, porosity) and then this relationship is used to fill in the rest of the seismic cube...