Imperial College London
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ProfessorMikeWarner

Faculty of Engineering, Department of Earth Science & Engineering

Professor
 
 
 
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Contact

 

+44 (0)20 7594 6535m.warner

 
 
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Assistant

 

Ms Daphne Salazar +44 (0)20 7594 7401

 
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Location

 

RSM 1.46CRoyal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Silverton:2015:10.1111/1365-2478.12336,
author = {Silverton, A and Warner, M and Morgan, J and Umpleby, A},
doi = {10.1111/1365-2478.12336},
journal = {Geophysical Prospecting},
pages = {1201--1214},
title = {Offset-variable density improves acoustic full-waveform inversion: a shallow marine case study},
url = {http://dx.doi.org/10.1111/1365-2478.12336},
volume = {64},
year = {2015}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We have previously applied three-dimensional acoustic, anisotropic, full-waveform inversion to a shallow-water, wide-angle, ocean-bottom-cable dataset to obtain a high-resolution velocity model. This velocity model produced: an improved match between synthetic and field data, better flattening of common-image gathers, a closer fit to well logs, and an improvement in the pre-stack depth-migrated image. Nevertheless, close examination reveals that there is a systematic mismatch between the observed and predicted datafrom this full-waveform inversion model, with the predicted data being consistently delayed in time. We demonstrate that this mismatch cannot be produced by systematic errors in the starting model, by errors in the assumed source wavelet, by incomplete convergence, or by the use of an insufficiently fine finite-difference mesh. Throughout these tests, the mismatch is remarkably robustwith the significant exception that we do not see an analogous mismatch when inverting synthetic acoustic data. We suspect therefore that the mismatch arises because of inadequacies in the physics that are used during inversion. For ocean-bottom-cabledata in shallow water at low frequency, apparent observed arrival times, in wide-angle turning-ray data, result from the characteristics of the detailed interference pattern between primary refractions, surface ghosts, and a large suite of wide-angle multiple reflected and/or multiple refracted arrivals. In these circumstances, the dynamics of individual arrivals can strongly influence the apparent arrival times of the resultant compound waveforms. In acoustic full-waveform inversion, we do not normally know the density of the seabed, and we do not properly account for finite shear velocity, finite attenuation, and fine-scale anisotropy variation, all of which can influence the relative amplitudes of different interfering arrivals, which in their turn influence the apparent kinematics. Here, wedemonstrate that the introduction of
AU  - Silverton,A
AU  - Warner,M
AU  - Morgan,J
AU  - Umpleby,A
DO  - 10.1111/1365-2478.12336
EP  - 1214
PY  - 2015///
SN  - 0016-8025
SP  - 1201
TI  - Offset-variable density improves acoustic full-waveform inversion: a shallow marine case study
T2  - Geophysical Prospecting
UR  - http://dx.doi.org/10.1111/1365-2478.12336
UR  - http://hdl.handle.net/10044/1/26123
VL  - 64
ER  -
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