The effect of velocity uncertainty on migrated reflectors: Improvements from relative-depth imaging

Poliannikov, Oleg V.; Malcolm, Alison

doi:10.1190/geo2014-0604.1

Cited by 17 publications

(7 citation statements)

References 17 publications

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“…One way in which our hypocenter location estimates could be placed artificially deep is through use of a velocity model that is slower than the true Earth velocity structure (e.g., Poliannikov & Malcolm, 2016). Where the velocity model used is incorrect, the direct‐search approach of NonLinLoc provides a better estimate of location hypocenter than linearized methods, as negative and positive TT residuals need not be balanced to produce a complete posterior probability distribution.…”

Section: Discussionmentioning

confidence: 99%

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Lower‐Crustal Seismicity on the Eastern Border Faults of the Main Ethiopian Rift

et al. 2020

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Lower‐crustal seismicity is commonly observed in continental rift zones despite the crust at such depths being ductile enough to prohibit brittle failure. The source of such deep seismicity across the East African Rift remains an outstanding question. Here we present analysis of an isolated cluster of lower‐crustal earthquakes located on the eastern border faults of the Main Ethiopian Rift, near the Corbetti caldera. Lower‐crustal earthquakes have not previously been observed in this area. Phase arrival times were determined using an automated picking approach based on continuous wavelet transform and statistical changepoint detection methods. We overcome misinterpretations from large hypocenter depth errors by considering mixture distributions for all events and their associated uncertainties. These mixture distributions represent probability density functions of any event occurring at a given depth. The mixture distribution mode for a variety of different velocity models and error parameters remained stable at a depth of 28–32 km, with the vast majority of maximum likelihood estimates for individual hypocenters located at depths of 25–35 km. Most events occur over a 2 month period, with 90% of cumulative seismic moment occurring during March and April 2012. The ephemeral and localized nature of this seismicity, combined with low event magnitudes and regional hydrothermal/magmatic activity, suggests that these lower‐crustal events are likely related to fluid or magmatic processes. Plausible mechanisms include the movement of magma and/or exsolution of volatiles at depth causing transient high strain rates and pore fluid pressures that induce seismicity.

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Section: Discussionmentioning

confidence: 99%

Section: Journal Of Geophysical Research: Solid Earthmentioning

confidence: 99%

Lower‐Crustal Seismicity on the Eastern Border Faults of the Main Ethiopian Rift

et al. 2020

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“…The monitor survey is therefore migrated with the incorrect velocity model (supposing, of course, that the correct velocity model has indeed been found for the baseline data). There have been studies on the sensitivity of stacked images to incorrect choices in velocity model and the reliability of the information content of the final stacked images (for example, Grubb et al ., 2001; Poliannikov and Malcolm 2016). These indicate that if the velocity corrections in the model are smooth, the continuity in the stacked amplitude of structural events remains largely more stable than their positions.…”

Section: Introductionmentioning

confidence: 99%

Review Paper: Methods of measurement for 4D seismic post‐stack time shifts

MacBeth

Amini

Izadian

2020

Geophysical Prospecting

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The estimation of time-lapse time shifts between two, or several, repeated seismic surveys has become increasingly popular over the past eighteen years. These time shifts are a reliable and informative seismic attribute that can relate to reservoir production. Correction for these time shifts or the underlying velocity perturbations and/or subsurface displacement in an imaging sense also permits accurate evaluation of time-lapse amplitudes by attempting to decouple the kinematic component. To date, there are approximately thirty methods for time-shift estimation described in the literature. We can group these methods into three main families of mathematical development, together with several miscellaneous techniques. Here we detail the underlying bases for these methods, and the acknowledged benefits and weaknesses of each class of method highlighted. We illustrate this review with a number of time-lapse seismic examples from producing fields. No method is necessarily superior to the others, as its selection depends on ease of implementation, noise characteristics of the field data, and whether the inherent assumptions suit the case in question. However, cross-correlation stands out as the algorithm of choice based on the Pareto principle and waveform inversion the algorithm delivering best resolution. This is a companion study to the previous review of time-shift magnitudes and a discussion of their rock physics basis.

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“…Several works discuss how to express the uncertainty related to velocity-model building and measure the impact on the migration techniques [1,2,3,4,5,6]. Typically, uncertainties are characterized through a probabilistic perspective and expressed as an ensemble of possible realizations of a random variable, making the Monte Carlo (MC) method the standard tool to manage and quantify uncertainties [7, 8, 9, 10, 11? ].…”

Section: Introductionmentioning

confidence: 99%

A workflow for seismic imaging with quantified uncertainty

Barbosa,

Kunstmann,

Silva

et al. 2020

Preprint

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The interpretation of seismic images faces challenges due to the presence of several uncertainty sources.Uncertainties exist in data measurements, source positioning, and subsurface geophysical properties.Understanding uncertainties' role and how they influence the outcome is an essential part of the decisionmaking process in the oil and gas industry. Geophysical imaging is time-consuming. When we add uncertainty quantification, it becomes both time and data-intensive. In this work, we propose a workflow for seismic imaging with quantified uncertainty. We build the workflow upon Bayesian tomography, reverse time migration, and image interpretation based on statistical information. The workflow explores an efficient hybrid parallel computational strategy to decrease the reverse time migration execution time.High levels of data compression are applied to reduce data transfer among workflow activities and data storage. We capture and analyze provenance data at runtime to improve workflow execution, monitoring, and debugging with negligible overhead. Numerical experiments on the Marmousi2 Velocity Model Benchmark demonstrate the workflow capabilities. We observe excellent weak and strong scalability, and results suggest that the use of lossy data compression does not hamper the seismic imaging uncertainty quantification.

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The effect of velocity uncertainty on migrated reflectors: Improvements from relative-depth imaging

Cited by 17 publications

References 17 publications

Lower‐Crustal Seismicity on the Eastern Border Faults of the Main Ethiopian Rift

Lower‐Crustal Seismicity on the Eastern Border Faults of the Main Ethiopian Rift

Review Paper: Methods of measurement for 4D seismic post‐stack time shifts

A workflow for seismic imaging with quantified uncertainty

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