CSEM/MT forward modeling & High-order edge finite element method

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 3D marine controlled-source electromagnetic (3D CSEM) method and 3D magnetotelluric (3D MT) method have become important techniques for reducing ambiguities in data interpretation in exploration geophysics. In order to be able to predict the EM signature of a given geological structure, modeling tools provide us with synthetic results which we can then compare to measured data. In particular, if the geology is structurally complex, one might need to use methods able to cope with such complexity in a natural way by means of, e.g., an unstructured mesh representing its geometry. Among the modeling methods for EM based upon 3D unstructured meshes, the high-order Nédélec Edge Finite Element Method (HEFEM) offers a good trade-off between accuracy and number of degrees of freedom, e.g. size of the problem. Furthermore, its divergence-free basis is very well suited for solving Maxwell’s equation. On top of that, we choose to support tetrahedral meshes, as these are the easiest to use for very large domains or complex geometries.

We refer to the following papers for a complete discussion of marine/land 3-D CSEM/MT modelling and its problem statement within PETGEM: