| Abstract: | Three-component recordings of shear-waves in exploration surveys provide an opportunity to measure crustal anisotropy, which may be important in estimating the geometrical and physical parameters of reservoir rocks. VSPs are particularly important for this purpose as they are less subject to the complex interactions of the shear wavefield with the free surface. The first stage in characterizing the subsurface anisotropy requires that the distinctive phenomenon of shear-wave splitting must be examined for every arrival at each geo-phone. This effect may be defined by two parameters: the polarization of the leading shear-wave and the time-delay between corresponding split shear-waves. A variety of techniques have been designed to estimate these parameters of shear-wave splitting. Here, we classify the published techniques into four main categories and review their properties. Representative procedures from each group are applied to a common synthetic data set contaminated with signal-generated noise. The results allow some general statements to be made about the utility of these methods for processing shear-waves in VSP data. |
