Time-migration velocity analysis by image-wave propagation of common-image gathers

Schleicher, Jörg; Costa, Jessé C.; Novais, Amélia

doi:10.1190/1.2968952

Cited by 33 publications

(9 citation statements)

References 49 publications

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“…If the data itself lacks reflection events to be used for a good velocity analysis across the whole velocity model, one needs to be careful with the interpretation of the reflectors in the final image. With the CIG analysis (e.g., Schleicher et al, 2008), it is possible to refine the velocity model in the future studies. Based on the flatness of those events in CIG images, we argue that the current velocity model works well for imaging the mineral deposits at the site, though the migration velocity needs to be updated for better imaging other subsurface structures.…”

Section: Discussionmentioning

confidence: 99%

Reverse time migration (RTM) imaging of iron-oxide deposits in the Ludvika mining area, Sweden

Ding¹,

Malehmir²

2020

Preprint

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Abstract. To discover or delineate mineral deposits and other geological features such as faults and lithological boundaries in their host rocks, seismic methods are a qualified choice, given their resolution power at depth. One major goal for seismic methods is to produce a reliable image of the subsurface given the typical discontinuous geology in crystalline environment with low signal-to-noise ratio. In this study, we investigate the usefulness of reverse time migration (RTM) imaging algorithm in hardrock environment by applying it to a legacy 2D dataset, which was acquired in the Ludvika mining area of central Sweden. We provide a how-to solution for applications of RTM in future and similar datasets. When using the RTM imaging technique properly, it is possible to obtain high-fidelity seismic images of the subsurface. Due to good amplitude preservation in the RTM image, the imaged reflectors provide indications to infer their geological origin. Aside from the chosen seismic imaging algorithm, we illustrate that two other important factors for successful RTM imaging workflows are the suitable acquisition and careful data pre-processing. Exemplified with the Ludvika legacy data, the RTM method allows imaging the iron-oxide deposits at a great level of detail down to 1200 m depth as shown from previous studies. It also provides much-improved images of the lithological contacts and crosscutting features relative to the mineralized sheets. Some of the imaged crosscutting features are considered to be crucial when interpreting large-scale geological structures of the site and the likely disappearance of mineralization at depth. The RTM imaging workflows have the potential to be used on hardrock seismic data and for deep targeting mineral deposits, a key message we would like to deliver in this article.

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Section: Discussionmentioning

confidence: 99%

Reverse time migration (RTM) imaging of iron-oxide deposits in the Ludvika mining area, Sweden

Ding¹,

Malehmir²

2020

Preprint

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“…Schleicher et al, 2008) or tomographic inversion (e.g. Lines and Newrick, 2004) of travel-time Green's functions.…”

Section: The Problem Settingmentioning

confidence: 99%

“…Lines and Newrick, 2004), of travel-time Green's functions, or by migration velocity analysis (e.g. Schleicher et al, 2008).…”

Section: Local Linear Waveform Inversionmentioning

confidence: 99%

Time-lapse seismic reservoir monitoring with a local waveform inversion technique

Lam

2010

Journal of Applied Geophysics

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“…Recently, we have studied different methods of obtaining an initial model for time time migration (Schleicher et al, 2008;Schleicher and Costa, 2009). Now, we are interested in how to refine such an initial model.…”

Section: Introductionmentioning

confidence: 99%

Coherence measures in automatic time migration velocity analysis

Maciel¹,

Costa²,

Schleicher

2011

SEG Technical Program Expanded Abstracts 2011

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Time-migration velocity analysis can be carried out automatically by evaluating the coherence of the migrated seismic events in the common-image gathers (CIGs). The performance of gradient methods for automatic time-migration velocity analysis depends on the the coherence measures used in the objective function. We compare the results of four different coherence measures, being conventional semblance, differential semblance, an extended differential semblance using more neighboring traces, and the product of the latter with conventional semblance. In our numerical experiments, the objective functions based on conventional semblance and on the product of conventional semblance with extended differential semblance provided the best velocity models, as evaluated by the flatness of the resulting common-image gathers. The method can be easily extended to anisotropic media.

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Time-migration velocity analysis by image-wave propagation of common-image gathers

Cited by 33 publications

References 49 publications

Reverse time migration (RTM) imaging of iron-oxide deposits in the Ludvika mining area, Sweden

Reverse time migration (RTM) imaging of iron-oxide deposits in the Ludvika mining area, Sweden

Time-lapse seismic reservoir monitoring with a local waveform inversion technique

Coherence measures in automatic time migration velocity analysis

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