Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data
We studied the validity of qP-wave slowness and slowness-polarization methods for estimating local anisotropy parameters in transversely isotropic (TI) media by quantifying the estimation errors in a numerical exercise. We generated numerical slownesses and polarizations over two aperture ranges cor...
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| Format: | Journal Article |
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Society of Exploration Geophysics
2013
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| Online Access: | http://library.seg.org/doi/abs/10.1190/geo2012-0409.1 http://hdl.handle.net/20.500.11937/8007 |
| _version_ | 1848745532247244800 |
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| author | Asgharzadeh, Mehdi Bona, Andrej Pevzner, Roman Urosevic, Milovan Gurevich, Boris |
| author_facet | Asgharzadeh, Mehdi Bona, Andrej Pevzner, Roman Urosevic, Milovan Gurevich, Boris |
| author_sort | Asgharzadeh, Mehdi |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We studied the validity of qP-wave slowness and slowness-polarization methods for estimating local anisotropy parameters in transversely isotropic (TI) media by quantifying the estimation errors in a numerical exercise. We generated numerical slownesses and polarizations over two aperture ranges corresponding to a short offset walkaway vertical seismic profiling (VSP) and a long offset walkaway VSP for a range of TI models with vertical axis of symmetry (VTI). Synthetic data are equisampled over the phase angle range and contaminated with Gaussian noise. We inverted the data and compared the anisotropy parameters of the optimal model with the true model. We found that the selection of a proper methodology for VTI parameter estimation based on walkaway VSP measurements was mostly dependent on our ability to accurately estimate either horizontal components of qP-wave slowness vector or the polarization vector. With data contaminated with noise, methods that include the horizontal component of the slowness vector had greater accuracy than the methods that replace this information with polarization measurements. The estimations are particularly accurate when a wide range of propagation angle was available. For short offsets, only parameter δ could be reliably estimated.In the absence of long offsets, depending on the accuracy of polarization measurements, the method based on the weak anisotropy approximation for qP-wave velocity in VTI media or the method based on slowness and polarization vectors could be used to estimate δ and ε . If the horizontal components of the slowness vector were not available (a heterogeneous overburden), we used methods that were based on local measurements of the polarization vector. We found that, with accurate measurements of the polarization vector, the method based on exact relationship between vertical slowness and polarization dip could be used to estimate VTI parameters even for the cases in which the wide offset range was not available. |
| first_indexed | 2025-11-14T06:18:51Z |
| format | Journal Article |
| id | curtin-20.500.11937-8007 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:18:51Z |
| publishDate | 2013 |
| publisher | Society of Exploration Geophysics |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-80072019-02-19T05:35:28Z Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data Asgharzadeh, Mehdi Bona, Andrej Pevzner, Roman Urosevic, Milovan Gurevich, Boris inversion vertical seismic profile (VSP) P-wave optimization anisotropy We studied the validity of qP-wave slowness and slowness-polarization methods for estimating local anisotropy parameters in transversely isotropic (TI) media by quantifying the estimation errors in a numerical exercise. We generated numerical slownesses and polarizations over two aperture ranges corresponding to a short offset walkaway vertical seismic profiling (VSP) and a long offset walkaway VSP for a range of TI models with vertical axis of symmetry (VTI). Synthetic data are equisampled over the phase angle range and contaminated with Gaussian noise. We inverted the data and compared the anisotropy parameters of the optimal model with the true model. We found that the selection of a proper methodology for VTI parameter estimation based on walkaway VSP measurements was mostly dependent on our ability to accurately estimate either horizontal components of qP-wave slowness vector or the polarization vector. With data contaminated with noise, methods that include the horizontal component of the slowness vector had greater accuracy than the methods that replace this information with polarization measurements. The estimations are particularly accurate when a wide range of propagation angle was available. For short offsets, only parameter δ could be reliably estimated.In the absence of long offsets, depending on the accuracy of polarization measurements, the method based on the weak anisotropy approximation for qP-wave velocity in VTI media or the method based on slowness and polarization vectors could be used to estimate δ and ε . If the horizontal components of the slowness vector were not available (a heterogeneous overburden), we used methods that were based on local measurements of the polarization vector. We found that, with accurate measurements of the polarization vector, the method based on exact relationship between vertical slowness and polarization dip could be used to estimate VTI parameters even for the cases in which the wide offset range was not available. 2013 Journal Article http://hdl.handle.net/20.500.11937/8007 http://library.seg.org/doi/abs/10.1190/geo2012-0409.1 Society of Exploration Geophysics restricted |
| spellingShingle | inversion vertical seismic profile (VSP) P-wave optimization anisotropy Asgharzadeh, Mehdi Bona, Andrej Pevzner, Roman Urosevic, Milovan Gurevich, Boris Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data |
| title | Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data |
| title_full | Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data |
| title_fullStr | Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data |
| title_full_unstemmed | Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data |
| title_short | Reliability of the slowness and slowness-polarization methods for anisotropy estimation in VTI media from 3C walkaway VSP data |
| title_sort | reliability of the slowness and slowness-polarization methods for anisotropy estimation in vti media from 3c walkaway vsp data |
| topic | inversion vertical seismic profile (VSP) P-wave optimization anisotropy |
| url | http://library.seg.org/doi/abs/10.1190/geo2012-0409.1 http://hdl.handle.net/20.500.11937/8007 |