2D Inversion of Ert Data Using Apparent Polarizability Curves

In the past two decades, automatic 2D inversion of ERT has been widely used. If geometrical soundings are carried out with measurement of the induced polarization, then one can interpret the curves of apparent resistivity and apparent polarizability with obtaining two deep-seated models - geoelectric and polarization. In the 1D version of the interpretation, the curves of apparent resistance and apparent polarizability were selected simultaneously in manual or semi-automatic mode. Two-dimensional inversion is often carried out completely automatically. As a rule, in the first stage, the inversion of the curves of apparent resistance is performed to obtain a deep model of resistivity, and in the second stage, the inversion of curves of apparent polarizability is already performed. This is the correct approach, since the two physical parameters obtained are related to each other. However, in some situations, the use of a resistivity model in the inversion of apparent polarizability leads to a deterioration in the result and an erroneous polarization model is obtained. This is especially noticeable in the case of inversion of low-quality data obtained under conditions of strong interference and with a low ratio of useful signal to noise. Our experience in the interpretation of ERT data shows that in some cases, the result of inversion of the curves of apparent polarizability without considering the resistance model provides a more consistent with the geology and balanced polarization model.