Pre-stack Inversion: Elastic Parameter Transformation

Once the 3 inversion volumes have been generated, we essentially have a version of a compressional sonic log, a Shear sonic log and a density log in the time domain at each trace location.  Therefore, we can use the transforms and relationships defined using the real well data to apply to these volumes, resulting in a series of elastic and petrophysical volumes that represents the desired property at each trace location. 

In essence we have turned each seismic amplitude trace into a set of well logs that will accurately characterise the rocks in the prospect.  That is the power of pre-stack inversion.

There is an option to generate EEI option here from the AI, SI and density logs. The advantage to generating it here from the rock properties rather than going through EEI reflectivity is that that method is more susceptible to errors. Here by reviewing the calculated Chi from a petrophysical log, GR for example, in the EEI Correlation this can be entered here and the EEI will be generated from the rock properties.

Select the elastic parameter you wish to transform. For conventional reservoirs it is common to generate Poisson’s Ratio and Lambda and Mu parameters. For shale play output required may well be Young’s Modulus or Young’s Modulus/Poisson Ratio.

Coloured Inversion Log Calibration Software diagram