Horizon-based Splitting Intensity Analysis and Inversion for Anisotropic Characterization

Analysing S-wave splitting has become a routine step in processing multicomponent data. Typically, this analysis leads to the determination of the principal directions of the anisotropic medium and to the time delays between the fast and slow S-waves. These parameters are estimated layer-by-layer from the top. Errors in layer stripping occurring in shallow layers might propagate to deeper layers.

We propose a different approach that consists of inverting interval values of splitting intensity to obtain a model of anisotropic parameters that vary with time or depth. Splitting intensity is a robust measurement with respect to structural variations and is commutative, which means that it can be summed along a ray (or throughout a sensitivity kernel volume) and can be linearly related to anisotropic perturbations at depth. Therefore, it is possible to estimate anisotropic properties within a geological formation (e.g., the reservoir) by analysing the differences of splitting intensity measured at the top and at the bottom of the layer. This allows us to avoid layer stripping, in particular, for shallow layers where anisotropic parameters are difficult to estimate due to poor coverage, and it makes S-wave splitting analysis simpler to apply. We demonstrate the method on synthetic and real data.