Rayleigh-Marchenko redatuming for target-oriented, true-amplitude imaging

Ravasi, Matteo

doi:10.1190/geo2017-0262.1

Cited by 90 publications

(74 citation statements)

References 57 publications

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“…The convergence of the Neumann series expansion for calculating the focusing functions, however, cannot be guaranteed in the presence of such multiples (Dukalski and de Vos ). Alternatively, when the reflection data is acquired with a source over spread streamer geometry, SRME can also be incorporated by directly inverting the modified Marchenko equations as described by Ravasi () and Slob and Wapenaar (). Naturally, the possible divergence of the Neumann series is not relevant for these direct inversion applications.…”

Section: Discussionmentioning

confidence: 99%

“…The resulting redatumed reflection response is migrated with RTM using only the velocity of the underburden. The redatumed reflection response can also be used for amplitude versus offset (AVO) studies (Ravasi ) or targeted velocity model building (Mildner et al . ).…”

Section: Methodsmentioning

confidence: 99%

“…; van der Neut, Vasconcelos and Wapenaar ) or by direct inversion (van der Neut et al . ; Ravasi ; Becker et al . ).…”

Section: Introductionunclassified

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Source wavelet correction for practical Marchenko imaging: A sub‐salt field‐data example from the Gulf of Mexico

Mildner

Broggini

Filho

et al. 2019

Geophysical Prospecting

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Imaging a target zone below a salt body can be challenging because large velocity contrasts in the overburden between the salt and surrounding sediments generate internal multiples, which interfere with primary reflections from the target level in the imaging process. This can lead to an erroneous interpretation of reflections in the sub‐salt area if multiples are misinterpreted as primaries. The Marchenko redatuming method may enable imaging of the sub‐salt target area where the effect of the multiply‐scattering overburden is removed. This is achieved by creating a redatumed reflection response where virtual sources and receivers are located below the overburden using a macromodel of the velocity field and the surface reflection data. The accuracy of the redatumed data and the associated internal multiple removal, however, depends on the accurate knowledge of the source wavelet of the acquired reflection data. For the first time, we propose a method which can accurately and reliably correct the amplitudes of the reflection response in field data as required by the Marchenko method. Our method operates by iteratively and automatically updating the source function so as to cancel the most artefact energy in the focusing functions, which are also generated by the Marchenko method. We demonstrate the method on a synthetic dataset and successfully apply it to a field dataset acquired in a deep‐water salt environment in the Gulf of Mexico. After the successful source wavelet estimation for the field dataset, we create sub‐salt target‐oriented images with Marchenko redatumed data. Marchenko images using the proposed source wavelet estimation show clear improvements, such as increased continuity of reflectors, compared to surface‐based images and to conventional Marchenko images computed without the inverted source wavelet. Our improvements are corroborated by evidence in the literature and our own synthetic results.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Source wavelet correction for practical Marchenko imaging: A sub‐salt field‐data example from the Gulf of Mexico

Mildner

Broggini

Filho

et al. 2019

Geophysical Prospecting

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“…Singh et al (2015) extend the scheme to account for free-surface related multiple reflections, such that the free-surface related multiple reflections would not need to be removed before the method can be applied. Ravasi (2017) extends the Marchenko scheme to eliminate free-surface and internal multiple reflections in one step in the marine seismic setting . Van der Neut and Wapenaar (2016) present the projected version of the Marchenko scheme by convolving both sides of the Marchenko equations with the first arrival of the transmission response in the truncated medium.…”

Section: Introductionmentioning

confidence: 99%

Artifact-free reverse time migration

et al. 2018

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We have derived an improved reverse time migration (RTM) scheme to image the medium without artifacts arising from internal multiple reflections. This is based on a revised implementation of Marchenko redatuming using a new time-truncation operator. Because of the new truncation operator, we can use the time-reversed version of the standard wavefield-extrapolation operator as initial estimate for retrieving the upgoing focusing function. Then, the retrieved upgoing focusing function can be used to directly image the medium by correlating it with the standard wavefieldextrapolation operator. This imaging scheme can be seen as an artifact-free RTM scheme with two terms. The first term gives the conventional RTM image with the wrong amplitude and artifacts due to internal multiple reflections. The second term gives a correction image that can be used to correct the amplitude and remove artifacts in the image generated by the first term. We evaluated the success of the method with a 2D numerical example.

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“…(). Alternative inversion schemes have been proposed if one assumes that the wavefield is recorded such that the vertical particle velocity data are properly sampled and can be obtained in separate up‐ and downgoing components (Ravasi ; Slob and Wapenaar ).…”

Section: Introductionmentioning

confidence: 99%

Marchenko imaging by unidimensional deconvolution

Matias

Pestana

Neut

2018

Geophysical Prospecting

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Obtaining an accurate image of the subsurface still remains a great challenge for the seismic method. Migration algorithms aim mainly on positioning seismic events in complex geological contexts. Multiple reflections are typically not accounted for in this process, which can lead to the emergence of artefacts. In Marchenko imaging, we retrieve the complete up‐ and downgoing wavefields in the subsurface to construct an image without such artefacts. The quality of this image depends on the type of imaging condition that is applied. In this paper, we propose an imaging condition that is based on stabilized unidimensional deconvolution. This condition is computationally much cheaper than multidimensional deconvolution, which has been proposed for Marchenko imaging earlier. Two specific approaches are considered. In the first approach, we use the full up‐ and downgoing wavefields for deconvolution. Although this leads to balanced and relatively accurate amplitudes, the crosstalk is not completely removed. The second approach is to incorporate the initial focussing function in the deconvolution process, in such a way that the retrieval of crosstalk is avoided. We compare images with the results of the classical cross‐correlation imaging condition, which we apply to reverse‐time migrated wavefields and to the up‐ and downgoing wavefields that are retrieved by the Marchenko method.

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Rayleigh-Marchenko redatuming for target-oriented, true-amplitude imaging

Cited by 90 publications

References 57 publications

Source wavelet correction for practical Marchenko imaging: A sub‐salt field‐data example from the Gulf of Mexico

Source wavelet correction for practical Marchenko imaging: A sub‐salt field‐data example from the Gulf of Mexico

Artifact-free reverse time migration

Marchenko imaging by unidimensional deconvolution

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