Seismic Image-Guided 3D Inversion of Marine CSEM and MT Data

Summary Marine controlled-source electromagnetic (CSEM) and magnetotelluric (MT) methods are used to map the distribution of horizontal and/or vertical resistivities in the subsurface for hydrocarbon investigations, but typically face the challenge of how to reduce non-uniqueness in the recovered boundary shapes and resistivities of 3D bodies embedded in a heterogeneous background. It is desirable to reduce structural ambiguity in resistivity models and also achieve structural compatibility with collocated higher fidelity physical models of the subsurface provided by 3D seismic images. Here, we extract structure tensors from seismic volumes and use the resulting boundary shapes to constrain the recovery of internal resistivities of 3D bodiesm by requiring in the inverse problem formulation that the cross-product of the gradients derived from the seismic image and the resistivity gradients is equal to zero at significant geological boundaries. Structural similarity between resistivity and seismic images is achieved without the requirement for any horizon interpretation or picking, thus reducing significantly the complexity and effort.