Near-Surface Scattering From High Velocity Carbonates In West Texas
Name
1998.2 Imhof et al.pdf
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1.06 MB
Format
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Checksum (MD5)
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Author(s)
Imhof, Matthias G.
Toksoz, M. Nafi
Burch, Charles I.
Queen, John H.
Date Issued
1998
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1998-02
Abstract
Seismic data acquired directly over near-surface limestone formations are commonly
observed to be of inferior quality. A possible cause for this degradation is scattering
in the near-subsurface by, e.g., the weathering layer, rough free-surface topography,
or heterogeneities such as cavities or clusters of vugs. We applied different numerical
scattering schemes to study the effects of each of these three scattering mechanisms.
For a particular dataset acquired in West Texas, we find that a weathering layer is
the dominant cause of noise on records acquired in valleys. However on mesas, nearsubsurface heterogeneity is the primary cause of scattered wave-energy. Topography
turned out to be of only secondary importance.
As additional attributes, we use energy-density and energy-flux vectors to study
the frequency dependence of the different scattering models. These attributes allow
us to study where energy concentrates and in which direction it flows. For example,
we observed that near sub-surface heterogeneities build up waveguides which efficiently
trap seismic energy near the surface.
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