Three-dimensional CSEM modelling on unstructured tetrahedral meshes using edge finite elements

Abstract

The last decade has been a period of rapid growth for electromagnetic methods (EM) in geophysics, mostly because of their industrial adoption. In particular, the marine controlled-source electromagnetic method (CSEM) has become an important technique for reducing ambiguities in data interpretation in hydrocarbon exploration. In order to be able to predict the EM signature of a given geological structure, modelling tools provide us with synthetic results which we can then compare to real data. On the other hand and among the modelling methods for EM based upon 3D unstructured meshes, the Nédélec Edge Finite Element Method (EFEM) offers a good trade-off between accuracy and number of degrees of freedom, i.e. size of the problem. Furthermore, its divergence-free basis is very well suited for solving Maxwell’s equation. On top of that, we present the numerical formulation and results of 3D CSEM modelling using the Parallel Edge-based Tool for Geophysical Electromagnetic Modelling (PETGEM) on unstructured tetrahedral meshes. We validated our experiments against quasi-analytical results in canonical models.