Seismic physical modeling II: VVAZ and AVAZ effects observed on reflections from isolated HTI targets

Joe Wong

ABSTRACT

Seismic physical modeling was used to investigate VVAZ and AVAZ phenomena associated with targets having HTI anisotropy. Land-type surveys were carried out for a two-layer model consisting of an isotropic elastic layer overlying an HTI layer. Transmission and reflection seismograms from these land surveys exhibit clear evidence of VVAZ effects. In addition, 3D marine surveys were conducted over isolated HTI targets embedded in an isotropic slab using acquisition geometries designed to emphasize AVAZ effects of reflections from the HTI targets. An attribute based on constant-offset reflection amplitudes and another attribute showing lamination orientations were extracted from the 3D datasets. On maps of these attributes, clear anomalies occur at the true locations of the HTI targets.

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