Simultaneous Joint Inversion of Electromagnetic and Seismic Full-waveform Data - A Sensitivity Analysis to Biot Parameter

We present and compare different methods for computing Gassmann’s fluid substitution model in the framework of the petrophysical simultaneous joint inversion of electromagnetic and seismic data. The algorithm we used computes elastic parameters using Gassmann’s model, while electrical resistivities are calculated using Archie’s law. In Gassmann’s model, the formulation of the Biot coefficient is critical to compute elastic properties of the saturated medium. Concerning the formulation of the Biot coefficient, along with testing the simultaneous joint inversion using expressions proposed in the models of Krief, Nur, Pride and Lee we also derived and tested a modified version of Krief’s model, which is inspired by that of Pride and Lee. As a result, for comparable misfits, Nur’s critical porosity model permits us to retrieve well the geometries of the medium, while Krief’s model allows us to retrieve sharper boundaries. Also, our study permits us to determine the influence of the formulation of the Biot parameter on inverted electrical resistivity distribution. In comparison to other models, the Pride and Lee model delineates quite well geometries of the synthetic model while being less efficient to retrieve electrical resistivity distribution. The modified Krief’s model provided slightly improved misfit with respect to Krief’s model.