oa Upscaling in Vertically Heterogeneous TTI Models

We define the low-frequency upscaling of vertically heterogeneous transversely isotropic layers with a tilted symmetry axis. In order to be used for velocity model building, the seismic wavelet is used as a weighting function. For a VTI medium, the low-frequency upscaling gives more accurate effective anisotropy parameters comparing with the ones obtained from Backus averaging. We also show that upscaling in TTI media results in much smaller effective tilt angle comparing with intrinsic one.