3D inversion of marine CSEM data: A feasibility study from the Shtokman gas field in the Barents Sea

We present a method and workflow for the 3D inversion for marine controlled-source electromagnetic (CSEM) data based on the 3D integral equation method with inhomogeneous background conductivity and focusing regularization with a priori terms. The use of focusing stabilizers makes it possible to recover subsurface models with sharper geoelectric contrasts and boundaries than traditional smooth stabilizers. Our inversion method is implemented in a parallelized code which makes it practical to run 3D inversion of 3D CSEM surveys to models with over a million cells. This makes it feasible to run multiple inversion scenarios that explore different regularization, a priori models, and data combinations. We present a suite of such interpretations for a synthetic 3D CSEM survey simulated from a very detailed model of the stacked anticline structures and reservoir units of the Shtokman gasfield in the Russian sector of the Barents Sea.