Unwrapped phase inversion with an exponential damping

Handle URI:
http://hdl.handle.net/10754/565051
Title:
Unwrapped phase inversion with an exponential damping
Authors:
Choi, Yun Seok; Alkhalifah, Tariq Ali ( 0000-0002-9363-9799 )
Abstract:
Full-waveform inversion (FWI) suffers from the phase wrapping (cycle skipping) problem when the frequency of data is not low enough. Unless we obtain a good initial velocity model, the phase wrapping problem in FWI causes a result corresponding to a local minimum, usually far away from the true solution, especially at depth. Thus, we have developed an inversion algorithm based on a space-domain unwrapped phase, and we also used exponential damping to mitigate the nonlinearity associated with the reflections. We construct the 2D phase residual map, which usually contains the wrapping discontinuities, especially if the model is complex and the frequency is high. We then unwrap the phase map and remove these cycle-based jumps. However, if the phase map has several residues, the unwrapping process becomes very complicated. We apply a strong exponential damping to the wavefield to eliminate much of the residues in the phase map, thus making the unwrapping process simple. We finally invert the unwrapped phases using the back-propagation algorithm to calculate the gradient. We progressively reduce the damping factor to obtain a high-resolution image. Numerical examples determined that the unwrapped phase inversion with a strong exponential damping generated convergent long-wavelength updates without low-frequency information. This model can be used as a good starting model for a subsequent inversion with a reduced damping, eventually leading to conventional waveform inversion.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Citation:
Unwrapped phase inversion with an exponential damping 2015, 80 (5):R251 GEOPHYSICS
Publisher:
Society of Exploration Geophysicists
Journal:
GEOPHYSICS
Issue Date:
28-Jul-2015
DOI:
10.1190/geo2014-0498.1
Type:
Article
ISSN:
0016-8033; 1942-2156
Additional Links:
http://library.seg.org/doi/10.1190/geo2014-0498.1
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorChoi, Yun Seoken
dc.contributor.authorAlkhalifah, Tariq Alien
dc.date.accessioned2015-08-04T12:37:10Zen
dc.date.available2015-08-04T12:37:10Zen
dc.date.issued2015-07-28en
dc.identifier.citationUnwrapped phase inversion with an exponential damping 2015, 80 (5):R251 GEOPHYSICSen
dc.identifier.issn0016-8033en
dc.identifier.issn1942-2156en
dc.identifier.doi10.1190/geo2014-0498.1en
dc.identifier.urihttp://hdl.handle.net/10754/565051en
dc.description.abstractFull-waveform inversion (FWI) suffers from the phase wrapping (cycle skipping) problem when the frequency of data is not low enough. Unless we obtain a good initial velocity model, the phase wrapping problem in FWI causes a result corresponding to a local minimum, usually far away from the true solution, especially at depth. Thus, we have developed an inversion algorithm based on a space-domain unwrapped phase, and we also used exponential damping to mitigate the nonlinearity associated with the reflections. We construct the 2D phase residual map, which usually contains the wrapping discontinuities, especially if the model is complex and the frequency is high. We then unwrap the phase map and remove these cycle-based jumps. However, if the phase map has several residues, the unwrapping process becomes very complicated. We apply a strong exponential damping to the wavefield to eliminate much of the residues in the phase map, thus making the unwrapping process simple. We finally invert the unwrapped phases using the back-propagation algorithm to calculate the gradient. We progressively reduce the damping factor to obtain a high-resolution image. Numerical examples determined that the unwrapped phase inversion with a strong exponential damping generated convergent long-wavelength updates without low-frequency information. This model can be used as a good starting model for a subsequent inversion with a reduced damping, eventually leading to conventional waveform inversion.en
dc.language.isoenen
dc.publisherSociety of Exploration Geophysicistsen
dc.relation.urlhttp://library.seg.org/doi/10.1190/geo2014-0498.1en
dc.rightsArchived with thanks to GEOPHYSICSen
dc.subjectinversionen
dc.subjectphaseen
dc.subjectfrequency-domainen
dc.titleUnwrapped phase inversion with an exponential dampingen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalGEOPHYSICSen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorChoi, Yun Seoken
kaust.authorAlkhalifah, Tariq Alien
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