Advanced modeling and inversion technologies for high-resolution electromagnetic methods

One of the most challenging problems in electromagnetic (EM) geophysical methods is developing fast and stable methods of EM modeling and inversion for 3-D inhomo­ geneous geoelectrical structures. In this paper I present an overview of the research conducted by the Consortium for Electromagnetic Modeling and Inversion (CEMI) at the University of Utah on developing fast forward mod­ eling and inversion technologies for high-resolution EM methods. We have recently developed a novel approach to 3-D EM modeling based on linearization of the inte­ gral equations for scattered EM fields (quasi-linear, QL, approximation). We have also developed a new approach to the solution of 3-D EM inverse problem based on QL approximation. The main advantage of the QL inversion is that we reduce the original nonlinear inverse problem to a set of linear inverse problems to obtain a rapid 3-D EM inversion. The inversion of the real data indicates that 3-D quasi-linear EM inversion is fast and stable and pro­ vides reasonable recovery of the models and real geological features. Thus, new technologies for high-resolution EM methods include fast and accurate forward modeling so­ lution and effective quasi-linear 3-D inversion scheme.