A new parameterization for waveform inversion in acoustic orthorhombic media
Type
ArticleAuthors
Masmoudi, Nabil
Alkhalifah, Tariq Ali

KAUST Department
Earth Science and Engineering ProgramPhysical Science and Engineering (PSE) Division
Seismic Wave Analysis Group
Date
2016-06-02Online Publication Date
2016-06-02Print Publication Date
2016-07Permanent link to this record
http://hdl.handle.net/10754/614404
Metadata
Show full item recordAbstract
Orthorhombic anisotropic model inversion is extra challenging because of the multiple parameter nature of the inversion problem. The high number of parameters required to describe the medium exerts considerable trade-off and additional nonlinearity to a full-waveform inversion (FWI) application. Choosing a suitable set of parameters to describe the model and designing an effective inversion strategy can help in mitigating this problem. Using the Born approximation, which is the central ingredient of the FWI update process, we have derived radiation patterns for the different acoustic orthorhombic parameterizations. Analyzing the angular dependence of scattering (radiation patterns) of the parameters of different parameterizations starting with the often used Thomsen-Tsvankin parameterization, we have assessed the potential trade-off between the parameters and the resolution in describing the data and inverting for the parameters. The analysis led us to introduce new parameters ϵd, δd, and ηd, which have azimuthally dependent radiation patterns, but keep the scattering potential of the transversely isotropic parameters stationary with azimuth (azimuth independent). The novel parameters ϵd, δd, and ηd are dimensionless and represent a measure of deviation between the vertical planes in orthorhombic anisotropy. Therefore, these deviation parameters offer a new parameterization style for an acoustic orthorhombic medium described by six parameters: three vertical transversely isotropic (VTI) parameters, two deviation parameters, and one parameter describing the anisotropy in the horizontal symmetry plane. The main feature of any parameterization based on the deviation parameters, is the azimuthal independency of the modeled data with respect to the VTI parameters, which allowed us to propose practical inversion strategies based on our experience with the VTI parameters. This feature of the new parameterization style holds for even the long-wavelength components of the model constrained by traveltimes.Citation
A new parameterization for waveform inversion in acoustic orthorhombic media 2016, 81 (4):R157 GEOPHYSICSSponsors
We would like to thank KAUST for financial support. We thank R. Djebbi and U. bin Waheed for many useful discussions. We are also grateful to the associate editor, A. Stovas and two anonymous reviewers for their critical and helpful review of the paper.Publisher
Society of Exploration GeophysicistsJournal
GEOPHYSICSAdditional Links
http://library.seg.org/doi/10.1190/geo2015-0635.1ae974a485f413a2113503eed53cd6c53
10.1190/geo2015-0635.1