Using downhole resistivity to better understand magnetotelluric inversion

Abstract

Previous studies have used downhole resistivity logs either as a direct constraint during magnetotelluric inversion or as a qualitative validation of inversion accuracy. This study instead uses synthetic 1D magnetotelluric modelling based on downhole resistivity to better understand results of 1D, 2D and 3D inversion. One-dimensional models with representative geology for the area were generated directly from downhole resistivity data. These models were used to generate synthetic data, which was then inverted using a range of methods. Synthetic modelling made a significant contribution to selecting an appropriate inversion technique and the quality of the interpretation. Joint use of SimPEG MT1D and Occam 2D inversions proved the most effective combination to understand the geology of the project area.