Elements of Seismic Dispersion: A Somewhat Practical Guide to Frequency-Dependent Phenomena

Liner, Christopher L.

doi:10.1190/1.9781560802952

Cited by 44 publications

(22 citation statements)

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“…It is assumed that shear rigidity is unaltered during the Gassmann fluid Figure 11. Frequency spectrum for the Dickman Field (Liner, 2012). The dominant frequency is around 35 Hz.…”

Section: Elastic Forward-modeling Resultsmentioning

confidence: 98%

Time-lapse seismic modeling for CO2 sequestration at the Dickman Oilfield, Kansas

Liner

Stewart

2014

GEOPHYSICS

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Carbon dioxide capture and injection into the subsurface has aroused great interest in the past few years as a method to enhance oil recovery and mitigate CO 2 emissions. The Dickman Oilfield located in Kansas provides two possible CO 2 sequestration targets: a regional deep saline reservoir (the primary objective) and a shallower mature depleted oil reservoir (secondary). We focused on the shallower depleted oil reservoir through a 250-year flow-simulation scenario and a fault leakage test. Seismic responses at various time intervals were simulated to help monitor CO 2 flow paths and injection stability. A complex and realistic geologic model with unconformity was embedded in the flow-simulation model. A regridding technique was used that assigned geologic values to a regular seismic grid that allowed 2D acoustic and elastic finite-difference simulation. Gassmann fluid substitution theory was used to obtain the reservoir properties with different CO 2 saturations, and the vertical seismic profile was used to assist in identifying geologic layers. A CO 2 plume and flow path from the leakage test can be detected from the differences in seismic data (5 to 10 ms time shift) from the first year of injection and the last year of monitoring. This was supported by comparison with the prestack field data available in the Dickman Oilfield. CO 2 -induced reflectivity changes are relatively larger for PS events than for PP events, implying that multicomponent data acquisition and processing may give added value to characterization and monitoring of carbon capture and storage projects. We assessed 4D seismic monitoring in the evaluation of long-term CO 2 containment stability for the Dickman Oilfield and suggested that time-lapse surveys will be useful.

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“…It is assumed that shear rigidity is unaltered during the Gassmann fluid Figure 11. Frequency spectrum for the Dickman Field (Liner, 2012). The dominant frequency is around 35 Hz.…”

Section: Elastic Forward-modeling Resultsmentioning

confidence: 98%

Time-lapse seismic modeling for CO2 sequestration at the Dickman Oilfield, Kansas

Liner

Stewart

2014

GEOPHYSICS

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“…Artifacts are not the focus of this work; however, a brief treatment is provided in the discussion. A more quantitative measure of comparison of the wavefields in Figure 6 is provided by using IC plots (Liner, 2012). Each panel in Figure 7 is a crossplot between the original and reconstructed amplitudes at each grid location, compared at one representative time (0.2 s).…”

Section: Mixed Value Reconstructionmentioning

confidence: 99%

Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

2015

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Five alternative algorithms were evaluated to circumvent the excessive storage requirement imposed by saving source wavefield snapshots used for the crosscorrelation image condition in 2D prestack elastic reverse time migration. We compared the algorithms on the basis of their ability, either to accurately reconstruct (not save) the source wavefield or to use an alternate image condition so that neither saving nor reconstruction of full wavefields was involved. The comparisons were facilitated by using the same (velocity-stress) extrapolator in all the algorithms, and running them all on the same hardware. We assumed that there was enough memory in a node to do an extrapolation, and that all input data were stored on disk rather than residing in randomaccess memory. This should provide a fair and balanced comparison. Reconstruction of the source wavefield from boundary and/or initial values reduced the required storage to a very small fraction of that needed to store source wavefield snapshots for conventional crosscorrelation, at the cost of adding an additional source extrapolation. Reverse time checkpointing avoided recursive forward recomputation. Two nonreconstructive imaging conditions do not require full snapshot storage or an additional extrapolation. Timebinning the imaging criteria removed the need for image time searching or sorting. Numerical examples using elastic data from the Marmousi2 model showed that the quality of the elastic prestack PP and PS images produced by the cost-optimized alternative algorithms were (virtually) identical to the higher cost images produced by traditional crosscorrelation.

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“…Although the spectral interference caused by closely spaced reflectors has been the subject of much study (Liner ) and been used to highlight thin bed tuning (Sinha et al . ), it is the aim of this paper to outline a method for accurately estimating the spectrum of a wavelet for use in seismic attenuation studies.…”

Section: Wedge Modelmentioning

confidence: 99%

The estimation of spectra from time‐frequency transforms for use in attenuation studies

Beckwith

Clark

Hodgson

2016

Geophysical Prospecting

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We introduce the signal dependent time–frequency distribution, which is a time–frequency distribution that allows the user to optimize the tradeoff between joint time–frequency resolution and suppression of transform artefacts. The signal‐dependent time–frequency distribution, as well as the short‐time Fourier transform, Stockwell transform, and the Fourier transform are analysed for their ability to estimate the spectrum of a known wavelet used in a tuning wedge model. Next, the signal‐dependent time–frequency distribution, and fixed‐ and variable‐window transforms are used to estimate spectra from a zero‐offset synthetic seismogram. Attenuation is estimated from the associated spectral ratio curves, and the accuracy of the results is compared. The synthetic consisted of six pairs of strong reflections, based on real well‐log data, with a modeled intrinsic attenuation value of 1000/Q = 20. The signal‐dependent time–frequency distribution was the only time–frequency transform found to produce spectra that estimated consistent attenuation values, with an average of 1000/Q = 26±2; results from the fixed‐ and variable‐window transforms were 24±17 and 39±10, respectively. Finally, all three time–frequency transforms were used in a pre‐stack attenuation estimation method (the pre‐stack Q inversion algorithm) applied to a gather from a North Sea seismic dataset, to estimate attenuation between nine different strong reflections. In this case, the signal‐dependent time‐frequency distribution produced spectra more consistent with the constant‐Q model of attenuation assumed in the pre‐stack attenuation estimation algorithm: the average L1 residuals of the spectral ratio surfaces from the theoretical constant‐Q expectation for the signal‐dependent time‐frequency distribution, short‐time Fourier transform, and Stockwell transform were 0.12, 0.21, and 0.33, respectively. Based on the results shown, the signal‐dependent time‐frequency distribution is a time–frequency distribution that can provide more accurate and precise estimations of the amplitude spectrum of a reflection, due to a higher attainable time–frequency resolution.

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Elements of Seismic Dispersion: A Somewhat Practical Guide to Frequency-Dependent Phenomena

Cited by 44 publications

References 0 publications

Time-lapse seismic modeling for CO2 sequestration at the Dickman Oilfield, Kansas

Time-lapse seismic modeling for CO2 sequestration at the Dickman Oilfield, Kansas

Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

The estimation of spectra from time‐frequency transforms for use in attenuation studies

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