Enhanced refractor imaging by supervirtual interferometry

Mallinson, Ian; Bharadwaj, Pawan; Schuster, Gerard T.; Jakubowicz, H.

doi:10.1190/1.3589113

Cited by 73 publications

(44 citation statements)

References 6 publications

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“…Second, the virtual refraction is the result of a summation of sources. This means that the virtual refraction has a larger S/N than the real refraction (Mallinson et al, 2011). These properties make the virtual refraction artifact a useful arrival for refraction statics estimation.…”

Section: The Modified Delay-time Methodsmentioning

confidence: 99%

“…These sources are positioned past the critical offset from the virtual shot and all receivers to the right. Thus, the virtual refraction signal-to-noise ratio is increased by ∼ ffiffiffiffi N p , where N is the number of sources in the summation (Mikesell et al, 2009;Bharadwaj et al, 2011;Mallinson et al, 2011). The virtual shot at 800 m is shown in Figure 2c, where the first break is now the phase that goes through t ¼ 0 s at the virtual shot position.…”

Section: An Elastic 2d Numerical Examplementioning

confidence: 99%

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A modified delay-time method for statics estimation with the virtual refraction

et al. 2012

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Topography and near-surface heterogeneities lead to traveltime perturbations in surface land-seismic experiments. Usually, these perturbations are estimated and removed prior to further processing of the data. A common technique to estimate these perturbations is the delay-time method. We have developed the "modified delay-time method," wherein we isolate the arrival times of the virtual refraction and estimate receiver-side delay times. The virtual refraction is a spurious arrival found in wavefields estimated by seismic interferometry. The new method removes the source term from the delay-time equation, is more robust in the presence of noise, and extends the lateral aperture compared to the conventional delay-time method. We tested this in an elastic 2D numerical example, where we estimated the receiver delay-times above a horizontal refractor. Taking advantage of reciprocity of the wave equation and rearranging the common shot gathers into common receiver gathers, isolated source delay times could also be obtained.

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Section: The Modified Delay-time Methodsmentioning

confidence: 99%

Section: An Elastic 2d Numerical Examplementioning

confidence: 99%

A modified delay-time method for statics estimation with the virtual refraction

et al. 2012

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“…The use of the far-field reciprocity equations of correlation and convolution types to create virtual diffractions and enhance their SNR is similar to that of Mallinson et al (2011), except diffraction energy is enhanced rather than refraction energy. I will assume an acoustic medium with an arbitrary velocity distribution with constant density, and wideband sources with unity amplitude at each frequency.…”

Section: Theorymentioning

confidence: 99%

Multi‐source least‐squares reverse time migration

Dai

Fowler²,

Schuster

2012

Geophysical Prospecting

288

109

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Least‐squares migration has been shown to improve image quality compared to the conventional migration method, but its computational cost is often too high to be practical. In this paper, we develop two numerical schemes to implement least‐squares migration with the reverse time migration method and the blended source processing technique to increase computation efficiency. By iterative migration of supergathers, which consist in a sum of many phase‐encoded shots, the image quality is enhanced and the crosstalk noise associated with the encoded shots is reduced. Numerical tests on 2D HESS VTI data show that the multisource least‐squares reverse time migration (LSRTM) algorithm suppresses migration artefacts, balances the amplitudes, improves image resolution and reduces crosstalk noise associated with the blended shot gathers. For this example, the multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with a comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution and fewer migration artefacts compared to conventional RTM. The empirical results suggest that multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with a similar or less computational cost. The caveat is that the LSRTM image is sensitive to large errors in the migration velocity model.

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“…In this case, traveltimes of far-offset traces cannot be accurately picked. To overcome this problem, Bharadwaj and Schuster (2010) and Mallinson et al (2011) developed the theory of super-virtual refraction interferometry to create head-wave arrivals with much improved SNR.…”

Section: Introductionmentioning

confidence: 99%