Velocity models from wide-angle seismic data by wavefield inversion

Pratt, R. G.; Song, Z. M.; Warner, Mike; Williamson, Paul

doi:10.3997/2214-4609.201410087

Cited by 28 publications

(46 citation statements)

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“…Although the reflector inversion is not explicitly restricted to recovering only high wavenumbers, high vertical wavenumbers dominate the model updates as a consequence of the survey geometry. The same gradient method algorithm recovers a wide range of wavenumber information when applied to crosshole and offset vertical seismic profiling (VSP) data (Pratt, 1990(Pratt, , 1999Song et al, 1995;Pratt and Shipp, 1999) or to wide-angle (refraction) data (Pratt et al, 1996;Brittan et al, 1997;Forgues et al, 1998).…”

Section: Gradient Method High-wavenumber Inversionmentioning

confidence: 98%

Reflection waveform inversion using local descent methods: Estimating attenuation and velocity over a gas‐sand deposit

2001

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Prestack seismic reflection data contain amplitudes, traveltimes, and moveout information; waveform inversion of such data has the potential to estimate attenuation levels, reflector depths and geometry, and background velocities. However, when inverting reflection data, strong nonlinearities can cause reflectors to be incorrectly imaged and can prevent background velocities from being updated. To successfully recover background velocities, previous authors have resorted to nonlinear, global search inversion techniques.We propose a two-step inversion procedure using local descent methods in which we perform alternate inversions for the reflectors and the background velocities. For our reflector inversion we exploit the efficiency of the back-propagation method when inverting for a large parameter set. For our background velocity inversion we use Newton inverse methods. During the background velocity inversions it is crucial to adaptively depth-stretch the model to preserve the vertical traveltimes. This reduces nonlinearity by largely decoupling the effects of the background velocities and reflectors on the data. Nonlinearity is further reduced by choosing to invert for slownesses and by inverting for a sparse parameter set which is partially defined using geological reflector picks.Applying our approach to shallow seismic data from the North Sea collected over a gas-sand deposit, we demonstrate that the proposed method is able to estimate both the geometry and internal velocity of a significant velocity structure not present in the initial model. Over successive iterations, the use of adaptive depth stretching corrects the pull-down of the base of the gas sand. Vertical background velocity gradients are also resolved. For an insignificant extra cost the acoustic attenuation parameter Q is included in the inversion scheme. The final attenuation tomogram contains realistic values of Q for the expected lithologies and for the effect of partial fluid saturation associated with a shallow bright spot. The attenuation image may also indicate the presence of fracturing.

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Section: Gradient Method High-wavenumber Inversionmentioning

confidence: 98%

Reflection waveform inversion using local descent methods: Estimating attenuation and velocity over a gas‐sand deposit

2001

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“…Based on the dynamic theory, wave equation waveform inversion (Tarantola, 1984a and1984b;Mora, 1987a and1987b;Pratt et al, 1996) uses the information of wave fi eld amplitude, phase, and frequency to determine subsurface elastic parameters. Therefore, waveform inversion resolution is higher than conventional raybased inversion , Pratt, 1999Operto et al, 2004;Ravaut et al, 2004;Operto et al, 2006;Bleibinhaus et al, 2007;Gao et al, 2007;Malinowski and Operto, 2008).…”

Section: Introductionmentioning

confidence: 99%

Frequency domain wave equation forward modeling using gaussian elimination with static pivoting

et al. 2011

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Frequency domain wave equation forward modeling is a problem of solving large scale linear sparse systems which is often subject to the limits of computational effi ciency and memory storage. Conventional Gaussian elimination cannot resolve the parallel computation of huge data. Therefore, we use the Gaussian elimination with static pivoting (GESP) method for sparse matrix decomposition and multi-source fi nite-difference modeling. The GESP method does not only improve the computational effi ciency but also benefi t the distributed parallel computation of matrix decomposition within a single frequency point. We test the proposed method using the classic Marmousi model. Both the single-frequency wave field and time domain seismic section show that the proposed method improves the simulation accuracy and computational effi ciency and saves and makes full use of memory. This method can lay the basis for waveform inversion.

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“…Our simulation of the seismic wavefield from one point to another on the surface in Cartesian coordinates does not involve the summation of eigenfunctions of normal modes. Unlike time-distance studies involving the use of first-order Born approximation, which only models up to the first-order terms in the perturbation (e.g., Jackiewicz et al 2007), the code used in this study simulates the full seismic wavefield without linearizing the acoustic wave equation (Pratt et al 1996). The perturbation is 5% faster at its maximum than the background velocity structure, which is taken to be Model S of ChristensenDalsgaard et al (1996), and tapers off to background levels toward its edges with a Gaussian decay ( Figure 2).…”

Section: Generation Of Synthetic Datamentioning

confidence: 99%

“…We use a two-dimensional finite-difference code with a simplified acoustic wave equation (Pratt et al 1996) to simulate the wavefield generated in a region with a sound-speed perturbation that resembles those beneath sunspots reported in previous studies (e.g., Zhao et al 2001). The acoustic wave equation used in the code is 1 ρc 2…”

Section: Generation Of Synthetic Datamentioning

confidence: 99%

“…In the helioseismic context, Tong et al (2003c) show, by establishing the sensitivity of the internal structure of helioseismic signals to sound-speed variations, that amplitude modeling is feasible. Such full waveform inversion has already been developed and successfully applied in terrestrial exploration seismology (e.g., Pratt et al 1996;Chironi et al 2006;Brenders & Pratt 2007) and studies based on cross-correlated signals from ambient terrestrial seismic noise (Shapiro et al 2005). Wavefield inversion of cross-correlated signals from terrestrial ambient seismic noise is based on the following principle: cross-correlation of a random isotropic wavefield obtained between two points on the surface gives rise to a waveform that differs only by a factor compared with the Green function between the two points (Shapiro et al 2005, and references therein).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Inversion of Full Acoustic Wavefield in Local Helioseismology: A Study With Synthetic Data

Cobden¹,

Tong²,

Warner³

2011

ApJ

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We present the first results from the inversion of full acoustic wavefield in the helioseismic context. In contrast to time-distance helioseismology, which involves analyzing the travel times of seismic waves propagating into the solar interior, wavefield tomography models both the travel times and amplitude variations present in the entire seismic record. Unlike the use of ray-based, Fresnel-zone, Born, or Rytov approximations in previous time-distance studies, this method does not require any simplifications to be made to the sensitivity kernel in the inversion. In this study, the acoustic wavefield is simulated for all iterations in the inversion. The sensitivity kernel is therefore updated while lateral variations in sound-speed structure in the model emerge during the course of the inversion. Our results demonstrate that the amplitude-based inversion approach is capable of resolving sound-speed structures defined by relatively sharp vertical and horizontal boundaries. This study therefore provides the foundation for a new type of subsurface imaging in local helioseismology that is based on the inversion of the entire seismic wavefield.

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Velocity models from wide-angle seismic data by wavefield inversion

Cited by 28 publications

References 0 publications

Reflection waveform inversion using local descent methods: Estimating attenuation and velocity over a gas‐sand deposit

Reflection waveform inversion using local descent methods: Estimating attenuation and velocity over a gas‐sand deposit

Frequency domain wave equation forward modeling using gaussian elimination with static pivoting

Inversion of Full Acoustic Wavefield in Local Helioseismology: A Study With Synthetic Data

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