Time Domain Electromagnetic Data Modeling based on Zohdy's Technique

The initial model, Jacobian matrix, Frechet derivatives, and digital look-up tables are essential components in most time-domain electromagnetic (TEM) data modeling methods in layered earth. Computations of these components in the modeling process are time-consuming as their determinations need to use iterative operations. Zohdy introduced an alternative method for the rapid inversion of direct current (DC) resistivity data obtained using the Wenner and Schlumberger electrode configurations. The methodology allows for the inclusion of a flexible number of layers, which are chosen in conjunction with the initial model based on the data-derived knowledge, and avoids large and iterative calculations of Jacobian matrix and Frechet derivatives. This paper presents an endeavor to enhance the outcomes of TEM data modeling or inversion utilizing the Zohdy's technique through the elimination of the look-up tables. In this study, various synthetic models of stratified geological formations are examined using the the above-mentioned methodology. The modeling findings demonstrate robustness even when 5% and 10% noise levels are entered into the dataset. Hence, this approach can be considered as a worthy method for TEM data inversion accompanying some levels of noise in the data.