TTI Anisotropic Depth Migration - Which Tilt Estimate Should We Use?

We perform a series of numerical modelling and migration experiment with different homogeneous TTI anisotropic media, characterized by tilt axis, polar velocity and anisotropy parameters. In the case of structurally conformable media, where the tilt of the medium coincides with the dip of the structure, great simplifications arise in the decoupling of the anisotropy parameters. In particular, positioning and short spread focusing become decoupled from long-spread behaviour. We show that in this case, the tilt of the medium can be observed with sufficient accuracy on an image obtained by isotropic or VTI elliptic migration with an educated estimate of the Thomsen parameter delta.