Numerical modeling of elastic-wave scattering by near-surface heterogeneities
Name
Almuhaidib-2013-Numerical modeling o.pdf
Size
11.04 MB
Format
Adobe PDF
Checksum (MD5)
8266f4b948de791029b0af7195e948c6
Author(s)
Almuhaidib, Abdulaziz M.
Toksoz, M. Nafi
Date Issued
May 2014
Journal
Geophysics
Publisher
Society of Exploration Geophysicists
Citation
Almuhaidib, Abdulaziz M., and M. Nafi Toksoz. “Numerical Modeling of Elastic-Wave Scattering by Near-Surface Heterogeneities.” Geophysics 79, no. 4 (May 27, 2014): T199–T217. © 2014 Society of Exploration Geophysicists
Version
Final published version
Abstract
In land seismic data, scattering from surface and near-surface heterogeneities adds complexity to the recorded signal and masks weak primary reflections. To understand the effects of near-surface heterogeneities on seismic reflections, we simulated seismic-wave scattering from arbitrary-shaped, shallow, subsurface heterogeneities through the use of a perturbation method for elastic waves and finite-difference forward modeling. The near-surface scattered wavefield was modeled by looking at the difference between the calculated incident (i.e., in the absence of scatterers) and the total wavefields. Wave propagation was simulated for several earth models with different near-surface characteristics to isolate and quantify the influence of scattering on the quality of the seismic signal. The results indicated that the direct surface waves and the upgoing reflections were scattered by the near-surface heterogeneities. The scattering took place from body waves to surface waves and from surface waves to body waves. The scattered waves consisted mostly of body waves scattered to surface waves and were, generally, as large as, or larger than, the reflections. They often obscured weak primary reflections and could severely degrade the image quality. The results indicated that the scattered energy depended strongly on the properties of the shallow scatterers and increased with increasing impedance contrast, increasing size of the scatterers relative to the incident wavelength, decreasing depth of the scatterers, and increasing attenuation factor of the background medium. Also, sources deployed at depth generated weak surface waves, whereas deep receivers recorded weak surface and scattered body-to-surface waves. The analysis and quantified results helped in the understanding of the scattering mechanisms and, therefore, could lead to developing new acquisition and processing techniques to reduce the scattered surface wave and enhance the quality of the seismic image.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology. Earth Resources Laboratory
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1190/GEO2013-0208.1
