This thesis studies the physical seismic modeling of a simulated fractured medium to examine
variations of seismic re
ection amplitudes with source-receiver o set and azimuth
(AVAZ). The intent is to extract information about the fracture orientation and magnitude
of the anisotropy of a naturally fractured medium. The simulated fractured medium
is constructed from phenolic LE-grade material which exhibits orthorhombic symmetry.
For initial characterization of the phenolic model, its elastic sti ness coe cients were
determined from group velocities. The group velocities along various directions were
obtained from three-component physical model transmission data. The phenolic model
approximates a weakly anisotropic layer with horizontal transverse isotropy (HTI).
Three-dimensional (3D) physical model re
ection data were acquired over a model
consisting of the simulated fractured layer sandwiched between two isotropic plexiglas
layers submerged in water. Interference between primary and ghost events was avoided
with a careful 3D seismic survey design. After deterministic amplitude corrections, including
a correction for the directivity e ect of the physical model transducers, re
amplitudes agreed with the amplitudes predicted by the Zoeppritz equations, con rming
the suitability of the 3D physical model data for a quantitative amplitude analysis.
Linear AVAZ inversions for the fracture orientation and HTI anisotropic parameters
(including shear-wave splitting parameter) were performed on P-wave re
from the top of the simulated fractured medium. Sensitivity analysis of the inversions
results, including variations of the background velocity model and maximum
incident angle used, con rms the accuracy of the amplitude analysis. The results reveal
that the amplitude analysis of the P-wave data alone allows for extraction the information
about the shear-wave anisotropy con ned in the P-wave multi-o set and multi-azimuth
amplitude data, without any S-measurements.