Prism waves in seafloor canyons and their effects on seismic imaging

Deeks, James; Lumley, David

doi:10.1190/geo2015-0014.1

Cited by 12 publications

(6 citation statements)

References 20 publications

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“…Traditional ray‐based and one‐way wave‐equation migrations can hardly meet the requirements of high‐precision imaging in complex seismic exploration areas (Zhu and Rline ; Sava and Hill ). Reverse time migration (RTM) based on the two‐way wave equation has advantages for media with arbitrary velocity variation and can be used to image prism waves (Jones ; Liu and Weglein ; Deeks and Lumley ), diffractions (Zhan et al . ; Silvestrov, Baina and Landa ; Dafni and Symes ) and multiples (Fleury ; Wang et al .…”

Section: Introductionmentioning

confidence: 99%

Imaging artefacts of artificial diving waves in reverse time migration: cause analysis in the angle domain and an effective removal strategy

Liu

Yan

et al. 2019

Geophysical Prospecting

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In areas with strong velocity gradients, traditional reverse time migration based on cross‐correlation imaging condition not only produces low‐frequency noise but also generates diving wave artefacts. The artefacts caused by diving waves have no typical low‐frequency characteristics and cannot be eliminated by simple high‐pass filtering approaches. We apply the wave‐field decomposition imaging condition to analyse the causes of false images in reverse time migration by decomposing the full wave‐field into up‐going and down‐going components in the angle domain. We find that artificial diving wave imaging artefacts, which are generated by the cross‐correlation between the up‐going source and down‐going receiver wave‐fields in areas with strong velocity gradients, arise at large angles. We propose an efficient strategy by means of the wavelength‐dependent smoothing operator to eliminate artefacts from artificial diving waves in reverse time migration. Specifically, the proposed method provides more reasonable down‐going wave‐fields in areas with sharp velocity constructs by considering the factor of varying seismic wavelengths during wave propagation, and the artificial components of diving waves are eliminated in a straightforward manner. Meanwhile, the other wave‐field components that contribute to true subsurface images are minimally affected. Benefiting from a smoothed velocity, the proposed method can be adapted to the traditional reverse time migration imaging frame, which reveals significant implementation potential for the seismic exploration industry. A salt model is designed and included to demonstrate the effectiveness of our approach.

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Section: Introductionmentioning

confidence: 99%

Imaging artefacts of artificial diving waves in reverse time migration: cause analysis in the angle domain and an effective removal strategy

Liu

Yan

et al. 2019

Geophysical Prospecting

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“…However, ray-based analysis has been hindered not only by the lack of sufficient offsets for picking shallow events, but also by the complex ray paths generated by steep canyon walls. Deeks and Lumley (2015) pointed out that multiple paths of prism waves are usually generated by the canyons, even at short offsets. Prism wave energy becomes stronger in narrow and deep canyons and creates shadow events in stacked images and CDP gathers (Deeks and Lumley, 2015;Debenham and Westlake, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Deeks and Lumley (2015) pointed out that multiple paths of prism waves are usually generated by the canyons, even at short offsets. Prism wave energy becomes stronger in narrow and deep canyons and creates shadow events in stacked images and CDP gathers (Deeks and Lumley, 2015;Debenham and Westlake, 2014). Confidence in picking proper RMO and geological events is low in the presence of prism waves.…”

Section: Introductionmentioning

confidence: 99%

Velocity model-building challenges and solutions for seabed- and paleo-canyons: A case study in Campos Basin, Brazil

Zhang

Subia

Sun

et al. 2017

SEG Technical Program Expanded Abstracts 2017

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The Campos Basin, offshore Brazil, features complex shallow geology in the forms of pronounced seabed canyons and paleo-canyons. The rapid variations in the velocity field due to these complex shallow geologic features can be difficult for ray-based tomography techniques to resolve, resulting in distorted images in deeper section. Full waveform inversion (FWI) is able to utilize the recorded diving-wave energy to resolve the high-resolution velocity model in these geologically complex areas. Additionally, dip-constrained non-linear slope tomography introduces dip constraints to ray-based residual move-out tomography and is able to capture smallscale velocity anomalies associated with these shallow heterogeneities. A combined workflow of FWI and dipconstrained tomography enabled Chevron to build accurate and detailed velocity models in the Campos Basin, resulting in fewer seismic image distortions. We demonstrate the method using a Campos Basin, Brazil narrow-azimuth streamer dataset.

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“…Youn and Zhou (2001) used a model-based estimate of internal multiples in their pre-stack depth migration method. Recently, Deeks and Lumley (2015) studied the effects of prism waves, generated for seafloor canyons, on seismic imaging and velocity estimation. Behura et al (2012) utilized an iterative procedure to image internal-scattering and single-scattering waves.…”

Section: Introductionmentioning

confidence: 99%

Least-squares Generalized Interferometric Multiple Imaging

Aldawood¹,

Hoteit²,

Alkhalifah³

2016

78th EAGE Conference and Exhibition 2016

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Imaging internal multiples properly has the potential to enhance the quality of the migrated images since they may illuminate subsurface zones that are poorly illuminated by single-scattering energy, such as vertical and nearly vertical faults, and salt flanks. The generalized interferometric multiple imaging procedure aims to migrate internally multiply-scattered energy. Imaging first-order internal multiples using this procedure is composed of a data extrapolation based datuming step, an interferometric crosscorrelation datuming step followed by a zero-lag cross-correlation imaging condition with the forward extrapolated datumed data. However, this procedure yields migrated images that suffers from low spatial resolution, and migration artifacts due to the datuming steps based on cross-correlation, cross-talk noise, and band-limited nature of the source wavelet. We propose a least-squares generalized interferometric multiple imaging procedure, in which we replace the first two datuming steps by least-squares datuming ones. The proposed framework would suppress the cross-talk noise and migration artifacts, and deconvolve the source wavelet. Therefore, it would enhance the resolution of the subsurface reflectivity distribution illuminated by first-order internal multiples. Application to two synthetic datasets improved the illumination of subsurface scatterers and the high-resolution delineation of a vertical fault plane using first-order internal multiples.

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Prism waves in seafloor canyons and their effects on seismic imaging

Cited by 12 publications

References 20 publications

Imaging artefacts of artificial diving waves in reverse time migration: cause analysis in the angle domain and an effective removal strategy

Imaging artefacts of artificial diving waves in reverse time migration: cause analysis in the angle domain and an effective removal strategy

Velocity model-building challenges and solutions for seabed- and paleo-canyons: A case study in Campos Basin, Brazil

Least-squares Generalized Interferometric Multiple Imaging

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