The Influence of Acquisition Geometry on Azimuthal Anisotropy Estimation

Horizontal transverse isotropy (HTI) is the simplest model for azimuthal anisotropy analysis and is widely used in parameter estimation. It implies a number of significant simplifications and assumptions. The reliability of parameter estimation depends to a large extent on the acquisition geometry. We have performed ellipse fitting on the normal move-out velocities of synthetic data for a simple HTI model. For a narrow-azimuth acquisition geometry the estimated anisotropy parameters are not representative of the subsurface even though they could be used to improve the stack response. For full-azimuth data the NMO ellipse can be reconstructed in a reliable way providing accurate estimates of the HTI parameters, even in the presence of considerable noise.