Reverse time migration of prism waves for salt flank delineation

Dai, Weihui; Schuster, Gerard T.

doi:10.1190/segam2013-0414.1

Cited by 15 publications

(4 citation statements)

References 10 publications

(11 reference statements)

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“…The terms in equations B-4 and B-6 correspond to the imaging condition for migration of prismatic waves in which the singly scattered wavepaths and the double scattered data are correctly accounted for. Similar analyses can be found in Dai and Schuster (2013).…”

Section: Appendix a Derivation Of The Normal Equationsupporting

confidence: 83%

“…We first apply our method to a simple L model (Dai and Schuster, 2013) (Figure 2a) that contains a horizontal reflector and a vertical reflector. The model grid is 201 × 151 in size, with a grid interval of 10 m. The acquisition system consists of 49 sources and 201 receivers on the surface, spaced at 40 and 10 m intervals, respectively.…”

Section: The L Modelmentioning

confidence: 99%

“…However, accurate positioning of the sharp reflectors adds complexity to the already difficult migration velocity model building process. The other category is to use the migration image of primary waves to generate back-scattered wavefield, avoiding the modification of the migration velocity model (Malcolm et al, 2009(Malcolm et al, , 2011Dai and Schuster, 2013;Alkhalifah, 2013, 2014). The images from primary waves and prismatic waves are then summed together with empirically chosen weighting coefficients for subsequent geologic interpretation.…”

Section: Introductionmentioning

confidence: 99%

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Joint least-squares reverse time migration of primary and prismatic waves

Yang

Liu

et al. 2019

GEOPHYSICS

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Direct imaging of the steeply dipping structures is challenging for conventional reverse time migration (RTM), especially when there are no strong reflectors in the migration velocity model. To address this issue, we have enhanced the imaging of the steeply dipping structures by incorporating the prismatic waves. We formulate the imaging problem in a nonlinear least-squares optimization framework because the prismatic waves cannot be linearly mapped from the model perturbation. Primary and prismatic waves are jointly imaged to provide a single consistent image that includes structures illuminated by both types of waves, avoiding the complexities in scaling and/or interpreting primary and prismatic images separately. A conjugate gradient algorithm is used to iteratively solve the least-squares normal equation. This inversion procedure can become unstable if directly using the recorded data for migration because it is hindered by the crosstalk caused by imaging primary waves with the prismatic imaging operator. Therefore, we isolate the prismatic waves from the recorded data and image them with the prismatic imaging operator. Our scheme only requires a kinematically accurate and smooth migration velocity model, without the need to explicitly embed the strong reflectors in the migration velocity model. Realistic 2D numerical examples demonstrate that our method can resolve the steeply dipping structures much better than conventional least-squares RTM of primary waves.

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Section: Appendix a Derivation Of The Normal Equationsupporting

confidence: 83%

Section: The L Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Joint least-squares reverse time migration of primary and prismatic waves

Yang

Liu

et al. 2019

GEOPHYSICS

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“…But the imaging results still have artificial ringings. Dai and Schuster (2013) directly applied the prismatic imaging condition to prismatic waves to image salt flanks, assuming that prismatic reflections have been separated from primary reflections. Zuberi and Alkhalifah (2014) used interferometry to develop a generalized internal multiple imaging (GIMI) method, where prismatic waves are predicted to become the leading scattering term by repeating interferometric cross-correlation and then migrate with the prismatic imaging condition.…”

Section: Introductionmentioning

confidence: 99%

Steeply dipping structure imaging with prismatic waves incorporating wavefield decomposition

Zheng

Liu

Yang

2023

Geophysical Prospecting

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Prismatic waves in seismic data can effectively delineate steeply dipping subsurface structures. However, the conventional migration of prismatic wave either requires the exact location of basement reflectors embedded in the accurate migration velocity model or the explicit isolation of prismatic wave from the recorded data to avoid crosstalk artefacts caused by mistaken imaging of primary reflections. Neither of the requirements is a trivial task for field data application with complicated subsurface structures. To image steeply dipping structures with an accurate but smooth enough migration velocity and without the need to extract prismatic waves from the recorded data, we analyse the prismatic imaging condition based on wavefield decomposition. In the up-and downgoing wavefield decomposition, the prismatic imaging condition can effectively remove the high-wavenumber artefacts with incorrect polarity. However, the expected steeply dipping image is buried in low-wavenumber noises. In contrast, the prismatic imaging condition based on left-and right-going wavefield decomposition can accurately isolate the artefacts induced by the mistaken migration of primary waves from the steeply dipping interfaces in the image and is free of low-wavenumber noises. Based on this analysis, we develop a reverse time migration workflow using the modified prismatic imaging condition to depict steeply dipping structures: First, we use the primary imaging condition based on the up-and-down-going wavefield decomposition to obtain an image that can approximate the basement reflectors. Then, we use the modified prismatic imaging condition based on left-and right-going wavefield decomposition to recover the steep interfaces. Finally, a combined subsurface image containing both basement reflectors and faults or steeply dipping structures is generated. We verify the feasibility and robustness of the modified prismatic imaging condition based reverse time migration method for delineating steeply dipping structures using several synthetic tests.

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Improving the Image Quality of High-Angle Interfaces and Subsalt Sediments Using High-Order Scattered Seismic Waves

Lin

Ding

et al. 2021

Pure Appl. Geophys.

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Reverse time migration of prism waves for salt flank delineation

Cited by 15 publications

References 10 publications

Joint least-squares reverse time migration of primary and prismatic waves

Joint least-squares reverse time migration of primary and prismatic waves

Steeply dipping structure imaging with prismatic waves incorporating wavefield decomposition

Improving the Image Quality of High-Angle Interfaces and Subsalt Sediments Using High-Order Scattered Seismic Waves

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