Show simple item record

dc.contributor.advisorTSvankin, I. D.
dc.contributor.authorPattnaik, Sonali
dc.date.accessioned2017-07-20T19:38:24Z
dc.date.accessioned2022-02-03T13:01:26Z
dc.date.available2017-07-20T19:38:24Z
dc.date.available2022-02-03T13:01:26Z
dc.date.issued2017
dc.identifierPattnaik_mines_0052N_11293.pdf
dc.identifierT 8309
dc.identifier.urihttps://hdl.handle.net/11124/171144
dc.descriptionIncludes bibliographical references.
dc.description2017 Summer.
dc.description.abstractWith the recent advances in seismic data acquisition, such as wide-azimuth, long-offset surveys and low-frequency sources, full-waveform inversion (FWI) has become an efficient tool in building high-resolution subsurface models. Conventional FWI relies mainly on diving waves to update the low-wavenumber components of the background model. However, such FWI algorithms may fail to provide a satisfactory model update for regions probed primarily by reflected waves. This typically occurs for deep target zones where the conventional FWI updates mostly the high-wavenumber model components due to the absence of diving waves. Reflection waveform inversion (RWI) has been developed to retrieve the intermediate-to-long wavelength model components in those deeper regions from reflection energy. In this thesis, I highlight the limitations of conventional waveform inversion when applied to reflections-dominated seismic data and propose a new implementation of RWI for acoustic VTI (transversely isotropic with a vertical symmetry axis) media. I extend the idea of scale separation between the background and perturbation models to VTI media and use an optimized parameterization to mitigate parameter trade-offs in RWI. The proposed workflow repeatedly alternates between updating the long-wavelength model components by fixing the perturbation model and the shorter-wavelength, migration-based reflectivity update. I develop an hierarchical two-stage approach that operates with the P-wave zero-dip normal-moveout velocity $V_{\rm nmo}$ and anisotropy coefficients $\delta$ and $\eta$. At the first stage, $V_{\rm nmo}$ is estimated by applying the Born approximation to a perturbation model in $\delta$ to compute the corresponding reflection data. Although the algorithm does not invert for $\delta$, this parameter helps improve the amplitude fit for the employed acoustic model that ignores the elastic nature of the subsurface. At the second stage, the parameter $\eta$, which can be constrained by far-offset data, is estimated from the obtained perturbation model in $V_{\rm nmo}$. The proposed 2D algorithm is tested on a horizontally layered VTI medium and the VTI Marmousi model. Application of a temporal correlation-based objective function significantly improves recovery of the long-wavelength $\eta$-component, as demonstrated on the Marmousi model.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2017 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.titleFull waveform inversion with reflected waves for acoustic 2D VTI media
dc.typeText
dc.contributor.committeememberSnieder, Roel, 1958-
dc.contributor.committeememberTrainor-Guitton, Whitney
dc.contributor.committeememberMartin, P. A.
thesis.degree.nameMaster of Science (M.S.)
thesis.degree.levelMasters
thesis.degree.disciplineGeophysics
thesis.degree.grantorColorado School of Mines


Files in this item

Thumbnail
Name:
Pattnaik_mines_0052N_11293.pdf
Size:
2.044Mb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record