Fault Delineation by Wavefield Inversion of Cross-Borehole Seismic Data

Pratt, R. G.; Shipp, Richard; Song, Z. M.; Williamson, Paul

doi:10.3997/2214-4609.201409234

Cited by 7 publications

(20 citation statements)

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“…Several researchers have achieved considerable improvements in tomographic (transmission) imaging from cross-borehole data by utilizing gradient methods for waveform inversion in conjunction with finite-difference modeling. Results with real crosshole data have been demonstrated by Zhou et al (1995), who use a time-domain approach, and by and Pratt et al (1995), who use a frequency-domain approach. The motivation in the use of waveform inversion for crosshole data (or other transmission data) is to improve the resolution when compared with traveltime inversion methods (Williamson, 1991;Williamson and Worthington, 1993).…”

Section: Introductionmentioning

confidence: 99%

Seismic waveform inversion in the frequency domain, Part 1: Theory and verification in a physical scale model

1999

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Seismic waveforms contain much information that is ignored under standard processing schemes; seismic waveform inversion seeks to use the full information content of the recorded wavefield. In this paper I present, apply, and evaluate a frequency-space domain approach to waveform inversion. The method is a local descent algorithm that proceeds from a starting model to refine the model in order to reduce the waveform misfit between observed and model data. The model data are computed using a full-wave equation, viscoacoustic, frequencydomain, finite-difference method. Ray asymptotics are avoided, and higher-order effects such as diffractions and multiple scattering are accounted for automatically. The theory of frequency-domain waveform/wavefield inversion can be expressed compactly using a matrix formalism that uses finite-difference/finite-element frequency-domain modeling equations. Expressions for fast, local descent inversion using back-propagation techniques then follow naturally. Implementation of these methods depends on efficient frequency-domain forward-modeling solutions; these are provided by recent developments in numerical forward modeling. The inversion approach resembles prestack, reverse-time migration but differs in that the problem is formulated in terms of velocity (not reflectivity), and the method is fully iterative. I illustrate the practical application of the frequencydomain waveform inversion approach using tomographic seismic data from a physical scale model. This allows a full evaluation and verification of the method; results with field data are presented in an accompanying paper. Several critical processes contribute to the success of the method: the estimation of a source signature, the matching of amplitudes between real and synthetic data, the selection of a time window, and the selection of suitable sequence of frequencies in the inversion. An initial model for the inversion of the scale model data is provided using standard traveltime tomographic methods, which provide a robust but low-resolution image. Twenty-five iterations of wavefield inversion are applied, using five discrete frequencies at each iteration, moving from low to high frequencies. The final results exhibit the features of the true model at subwavelength scale and account for many of the details of the observed arrivals in the data.

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Section: Introductionmentioning

confidence: 99%

Seismic waveform inversion in the frequency domain, Part 1: Theory and verification in a physical scale model

1999

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“…Lastly, relic hunters have a strong knowledge of the battles and skirmishes of the Civil War, and many of the topsoil artifacts on such sites have been lost to metal-detector activity. Despite these limitations, many researchers have extracted significant data from such sites (e.g., Connor and Scott, 1998;Fox, 1993;Harbison, 2001;Pratt, 1995;Scott, 1994;Scott and Hunt, 1998;Scott et al, 1989;Sterling, 2001;Sterling and Slaughter, 2001; Whitehorne and Geier, 2001).…”

Section: Special Nature Of Civil War Sitesmentioning

confidence: 99%

The Value and Treatment of Civil War Military Sites

Espenshade¹,

Jolley²,

Legg³

2002

North American Archaeologist

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The American Civil War was a defining event in the history of the United States, and scholarly and public interest in the conflict remains high. Archaeological sites from the Civil War can provide valuable data that cannot be gleaned from the archival record or oral history. The archaeological study of battlefields, skirmish sites, earthworks, trenches, camps, and picket posts provides specific details that augment the other data sources. However, the archaeological treatment of Civil War sites-specifically the use of inappropriate methods-continues to be a problem. As many areas of the heartland of the Civil War face growing development pressures, it is imperative that archaeologists reconsider their approaches to Civil War sites.

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“…Full-waveform inversion (FWI) is a technique for estimating subsurface properties by using entire seismic waveforms recorded at the surface or in a borehole. Depending on the problem and availability of forward-modeling algorithms, FWI can be performed in the time domain (Kolb et al, 1986;Gauthier, 1986;Mora, 1987;Bunks et al, 1995) or frequency domain (Song and Williamson, 1995;Song et al, 1995;Pratt, 1999;Pratt and Shipp, 1999). Evaluation of the gradient of the objective function is often based on the adjoint state method, as described in Tarantola (1984a), Fichtner et al (2006), and Liu and Tromp (2006).…”

Section: Introductionmentioning

confidence: 99%

Gradient computation for elastic full-waveform inversion in 2D VTI media

Kamath

Tsvankin

2013

SEG Technical Program Expanded Abstracts 2013

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Full-waveform inversion (FWI) has proved effective in significantly improving the spatial resolution of seismic models. However, it is implemented mostly for isotropic media and the applications to anisotropic models are often limited to acoustic approximations. In a previous publication, we introduced a methodology for performing FWI of multicomponent (PP and PS) reflection data from a stack of horizontal, homogeneous VTI (transversely isotropic with a vertical symmetry axis) layers. Taking into account both anisotropy and elasticity in the description of the reflected wavefield makes it possible to resolve the interval Thomsen parameters and constrain the depth scale of the model. Here, we develop a foundation for extending elastic FWI to laterally heterogeneous VTI media using the adjoint state method. The main focus is on deriving the gradients of the objective function with respect to the model parameters. To test the algorithm, we introduce Gaussian anomalies in the Thomsen parameters of a homogeneous VTI medium and study the influence of the size of the anomaly, the sourcereceiver configuration, and the source polarization on the gradients. The model update for FWI can be produced by an appropriate scaling of the gradient using the steepest descent or similar methods.

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Fault Delineation by Wavefield Inversion of Cross-Borehole Seismic Data

Cited by 7 publications

References 0 publications

Seismic waveform inversion in the frequency domain, Part 1: Theory and verification in a physical scale model

Seismic waveform inversion in the frequency domain, Part 1: Theory and verification in a physical scale model

The Value and Treatment of Civil War Military Sites

Gradient computation for elastic full-waveform inversion in 2D VTI media

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