Automatic velocity analysis via shot profile migration

Shen, Peng; Symes, William W.

doi:10.1190/1.2972021

Cited by 236 publications

(158 citation statements)

References 22 publications

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“…7) for the residual image, which is defined as a multiplication of the extended image by h. Although this operator is very intuitive and was derived in Shen & Symes (2008) from the derivative operator that measures the flatness of the seismic energy in the angle domain CIG, it has been recognized that a more sophisticated operator is required for better focusing of the energy at zero subsurface space-lag and reducing noise at large lags (e.g. Shan & Wang 2013;Weibull & Arntsen 2013).…”

Section: Discussionmentioning

confidence: 99%

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Source-independent full wavefield converted-phase elastic migration velocity analysis

Shabelansky

Malcolm

Fehler

et al. 2014

Geophysical Journal International

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S U M M A R YConverted phase (CP) elastic seismic signals are comparable in amplitude to the primary signals recorded at large offsets and have the potential to be used in seismic imaging and velocity analysis. We present an approach for CP elastic wave equation velocity analysis that does not use source information and is applicable to surface-seismic, microseismic, teleseismic and vertical seismic profile (VSP) studies. Our approach is based on the crosscorrelation between reflected or transmitted PP and CP PS (and/or SS and CP SP) waves propagated backward in time, and is formulated as an optimization problem with a differential semblance criterion objective function for the simultaneous update of both P-and S-wave velocity models. The merit of this approach is that it is fully data-driven, uses full waveform information, and requires only one elastic backward propagation to form an image rather than the two (one forward and one backward) propagations needed for standard reverse-time migration. Moreover, as the method does not require forward propagation, it does not suffer from migration operator source aliasing when a small number of shots are used. We present a derivation of the method and test it with a synthetic model and field micro-seismic data.Key words: Inverse theory; Body waves; Seismic tomography; Computational seismology; Wave propagation. I N T RO D U C T I O NIn recent years, full waveform seismic imaging and velocity analysis methods have become standard and the use of elastic waves is now drawing more attention. Converted phase (CP) waves are an integrated part of the recorded elastic seismic signal and are investigated in numerous studies in the research areas of vertical seismic profile (VSP) data (e.g. Esmersoy 1990; Stewart 1991; Xiao & Leaney 2010), surface reflection (e.g. Purnell 1992;Stewart et al. 2003;Hardage et al. 2011) and transmission seismic data (e.g. Vinnik 1977;Vinnik et al. 1983;Bostock et al. 2001;Rondenay et al. 2001;Brytic et al. 2012;Shang et al. 2012;Shabelansky et al. 2013). In particular, for example Xiao & Leaney (2010) and Shang et al. (2012) showed that the CP seismic images can be calculated using one elastic propagation without using source information (i.e. location, mechanism and time-function). Source information is generally considered mandatory in standard seismic imaging and velocity analysis. However, in * Now at: Earth Sciences Department, Memorial University of Newfound- passive monitoring source information is generally not available and in active source surveys seismic data require special treatment for frequency matching due to coupling differences between soil and vibro-seis or dynamite casing. These factors affect the accuracy of the imaging and velocity estimation and add computational and processing cost. Moreover, CP elastic seismic imaging is shown to have higher resolution in Xiao & Leaney (2010) and fewer artifacts than reflection type imaging in Shabelansky et al. (2012). In this study, we present a source-independent CP (SICP) velocity anal...

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Section: Discussionmentioning

confidence: 99%

“…In general, we add additional regularization terms to eq. (7) as discussed in for example, Shen & Symes (2008) and Shen (2012). These terms do not affect the understanding of the derivation and so will not be further discussed.…”

Section: Derivation Of the Sicp-wemva Optimizationmentioning

confidence: 99%

Source-independent full wavefield converted-phase elastic migration velocity analysis

Shabelansky

Malcolm

Fehler

et al. 2014

Geophysical Journal International

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“…So to obtain a unique solution, we add some penalty term on w away from a δ function. Thus, similar to Shen and Symes (2008) and Huang et al (2016), we use the following optimization problem…”

Section: Theorymentioning

confidence: 99%

A New Wave Equation Based Source Location Method with Full-waveform Inversion

Wu¹,

Alkhalifah²

2017

Proceedings

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SummaryLocating the source of a passively recorded seismic event is still a challenging problem, especially when the velocity is unknown. Many imaging approaches to focus the image do not address the velocity issue and result in images plagued with illumination artifacts. We develop a waveform inversion approach with an additional penalty term in the objective function to reward the focusing of the source image. This penalty term is relaxed early to allow for data fitting, and avoid cycle skipping, using an extended source. At the later stages the focusing of the image dominates the inversion allowing for high resolution source and velocity inversion. We also compute the source location explicitly and numerical tests show that we obtain good estimates of the source locations with this approach.

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“…the modeled amplitudes are not accurate, then the chances for convergence diminish. Alternatively, one can optimize the model in the image space using techniques from the family usually referred to as wavefield tomography (Fliedner & Bevc, 2008;Sava & Biondi, 2004;Shen & Symes, 2008;Woodward, 1992;Yang & Sava, 2011a). The image domain approach seeks the kinematic synchronization of the wavefields at an image location.…”

Section: Introductionmentioning

confidence: 99%

“…Velocity Analysis (WEMVA) (Fliedner & Bevc, 2008;Sava & Biondi, 2004;Shen & Symes, 2008;Weibull & Arntsen, 2013;Woodward, 1992;Yang & Sava, 2011a).…”

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confidence: 99%

Understanding the reverse time migration backscattering: noise or signal?

Díaz

Sava

2015

Geophysical Prospecting

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Reverse time migration (RTM) backscattered events are produced by the cross-correlation between waves reflected from sharp interfaces (e.g. the top of salt bodies). Commonly, these events are seen as a drawback for the RTM method because they obstruct the image of the geologic structure. Many strategies have been developed to filter out the artifacts from the conventional image. However, these events contain information that can be used to analyze kinematic synchronization between source and receiver wavefields reconstructed in the subsurface. Numeric and theoretical analysis indicate the sensitivity of the backscattered energy to velocity accuracy: an accurate velocity model maximizes the backscattered artifacts. The analysis of RTM extended images can be used as a quality control tool and as input to velocity analysis designed to constrain salt models and sediment velocity.The analysis in this thesis suggest that we can use backscattering events along with reflection data to define a joint optimization problem for velocity model building. The gradient required for model optimization suffers from cross-talk, similar to the more conventional RTM images. In order to avoid the cross-talk, I use a directional filter based on Poynting vectors which preserves the components of the wavefield traveling in the same direction.Using backscattered waves for constraining the velocity in the sediment section requires defining the top of salt in advance, which implies a dynamic workflow for model building in salt environments where both sediment velocity and salt interface change iteratively during inversion.

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Automatic velocity analysis via shot profile migration

Cited by 236 publications

References 22 publications

Source-independent full wavefield converted-phase elastic migration velocity analysis

Source-independent full wavefield converted-phase elastic migration velocity analysis

A New Wave Equation Based Source Location Method with Full-waveform Inversion

Understanding the reverse time migration backscattering: noise or signal?

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