Physical Modeling and Analysis of Seismic Data from a Simulated Fractured Medium

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 ection 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 ection amplitudes 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.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Discipline thesis:degree_discipline

Geoscience

Grantor dc:publisher.institution

Graduate Studies

Year dc:date.issued

2013

Author dc:creator

• Mahmoudian, faranak

Advisor dc:contributor.advisor

• Margrave, Gary Frank

• Geophysics

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

eng

DOI

http://dx.doi.org/10.11575/PRISM/27350

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:11023/834