CSEM inversion: Impact of anisotropy, data coverage, and initial models

Abstract

While 3‐D inversion is a particularly effective tool for interpreting marine CSEM data, 3‐D data acquisition is needed to image the resistivity structure of an anisotropic subsurface. Tests on synthetic models show resistivity artifacts when anisotropic data are forced through isotropic inversion and when offline data are excluded from anisotropic inversions. Similar artifacts appear also when the inversion starting model differs too much from the actual subsurface. As a result, inadequate attention to anisotropy or inadequate data coverage can lead directly to misinterpretation of the subsurface resistivity structure. Anisotropic imaging with good data coverage, accurate receiver orientation, and good initial resistivity models are necessary to quantitatively image resistive anomalies in an anisotropic earth.