Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands
<jats:p> The generation of short-period multiples between highly heterogeneous layers of basalt flows can strongly alter transmitted seismic wavefields. These layers filter and modify penetrating waves, producing apparent attenuation and phase changes in the observed waveforms. We investigated...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/247609 2024-02-04T10:00:19+01:00 Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands Schuler, J Christie, PAF White, RS 2015 application/pdf https://www.repository.cam.ac.uk/handle/1810/247609 English eng eng Society of Exploration Geophysicists http://dx.doi.org/10.1190/geo2014-0308.1 Geophysics https://www.repository.cam.ac.uk/handle/1810/247609 37 Earth Sciences 3706 Geophysics Article 2015 ftunivcam 2024-01-11T23:28:27Z <jats:p> The generation of short-period multiples between highly heterogeneous layers of basalt flows can strongly alter transmitted seismic wavefields. These layers filter and modify penetrating waves, producing apparent attenuation and phase changes in the observed waveforms. We investigated the waveform and apparent phase changes of the primary seismic signal using mainly the maximum kurtosis approach. We compared the seismic recordings from two short-offset vertical seismic profiles (VSPs) with synthetic seismograms, generated from sonic logs in the same wells, and we found that short-period multiples cause a rapid broadening of the primary arrivals and strong apparent phase changes within a short depth interval below the top of the basalt flows. Relatively large uncertainties were associated with estimating constant phase shifts of the seismic arrivals within the topmost 250 m of the basalt sequences, where complex scattering occurred. Within this interval of the Brugdan I well, a phase-only compensation of the first arrivals with a frequency-independent, combined scattering, and intrinsic attenuation operator was unfeasible. At a greater depth, we found that the phase shifts, predicted by a VSP-derived effective [Formula: see text] value, were similar to those estimated from the VSP signals using the kurtosis method. Thus, phase-only compensation with a combined scattering and intrinsic attenuation operator could work well depending on the seismic signal bandwidth and the distribution, depth, and magnitude of the impedance contrasts in the basalt sequence. </jats:p> We wish to thank Shell UK Ltd. and BP for providing the data sets and for the permission to publish them. The views expressed herein, however, are those of the authors, who are solely responsible for any errors. We thank J. Neep and two anonymous reviewers for critically reading the manuscript. Thanks go to A/S Norske Shell, Schlumberger Gould Research, and the Natural Environment Research Council (grant no. NE/H025006/1) for ... Article in Journal/Newspaper Faroe Islands Apollo - University of Cambridge Repository Faroe Islands |
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Open Polar |
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Apollo - University of Cambridge Repository |
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language |
English |
topic |
37 Earth Sciences 3706 Geophysics |
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37 Earth Sciences 3706 Geophysics Schuler, J Christie, PAF White, RS Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands |
topic_facet |
37 Earth Sciences 3706 Geophysics |
description |
<jats:p> The generation of short-period multiples between highly heterogeneous layers of basalt flows can strongly alter transmitted seismic wavefields. These layers filter and modify penetrating waves, producing apparent attenuation and phase changes in the observed waveforms. We investigated the waveform and apparent phase changes of the primary seismic signal using mainly the maximum kurtosis approach. We compared the seismic recordings from two short-offset vertical seismic profiles (VSPs) with synthetic seismograms, generated from sonic logs in the same wells, and we found that short-period multiples cause a rapid broadening of the primary arrivals and strong apparent phase changes within a short depth interval below the top of the basalt flows. Relatively large uncertainties were associated with estimating constant phase shifts of the seismic arrivals within the topmost 250 m of the basalt sequences, where complex scattering occurred. Within this interval of the Brugdan I well, a phase-only compensation of the first arrivals with a frequency-independent, combined scattering, and intrinsic attenuation operator was unfeasible. At a greater depth, we found that the phase shifts, predicted by a VSP-derived effective [Formula: see text] value, were similar to those estimated from the VSP signals using the kurtosis method. Thus, phase-only compensation with a combined scattering and intrinsic attenuation operator could work well depending on the seismic signal bandwidth and the distribution, depth, and magnitude of the impedance contrasts in the basalt sequence. </jats:p> We wish to thank Shell UK Ltd. and BP for providing the data sets and for the permission to publish them. The views expressed herein, however, are those of the authors, who are solely responsible for any errors. We thank J. Neep and two anonymous reviewers for critically reading the manuscript. Thanks go to A/S Norske Shell, Schlumberger Gould Research, and the Natural Environment Research Council (grant no. NE/H025006/1) for ... |
format |
Article in Journal/Newspaper |
author |
Schuler, J Christie, PAF White, RS |
author_facet |
Schuler, J Christie, PAF White, RS |
author_sort |
Schuler, J |
title |
Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands |
title_short |
Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands |
title_full |
Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands |
title_fullStr |
Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands |
title_full_unstemmed |
Effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore Faroe Islands |
title_sort |
effect of flood basalt stratigraphy on the phase of seismic waveforms recorded offshore faroe islands |
publisher |
Society of Exploration Geophysicists |
publishDate |
2015 |
url |
https://www.repository.cam.ac.uk/handle/1810/247609 |
geographic |
Faroe Islands |
geographic_facet |
Faroe Islands |
genre |
Faroe Islands |
genre_facet |
Faroe Islands |
op_relation |
https://www.repository.cam.ac.uk/handle/1810/247609 |
_version_ |
1789965542939951104 |