Kansas Geological Survey
Stratigraphic Research
Seminar Series No. 8
"SPICE: A New General Seismic Attribute"
Dr. Chris Liner
Geophysical Consultant
EXPEC Advanced Research
Center (Geophysics)
Saudi Aramco
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10:30 am, Wednesday, August 1, 2007
Hambleton Auditorium
Spice is a new seismic interpretation attribute developed by C.-F. Li and C. L. Liner, and a patented invention owned
by The University of Tulsa.
Imagine a well with sonic and density logs from which we can construct an acoustic impedance (AI) curve, and from
this a reflection coefficient (RC) series, and then convolve with a seismic wavelet to form a synthetic seismogram (SYN). Spice
has the following remarkable property: Spice curves generated from AI, RC, and SYN have the same shape. And this is true
for different seismic wavelets. In a sense, Spice looks through the wavelet and reflection coefficient series to form a shadow
image of the underlying geological layering.
A distant cousin of spectral decomposition, the physical basis of Spice relates to spectral shaping during the reflection
process, local transmission losses, and thin bed effects. Unlike spectral decomposition, there is no data proliferation in Spice. It
operates in such a way that one trace in gives one trace out. A migrated data cube generates a Spice cube of the same
dimensions.
Intriguing stratigraphic relationships can be seen throughout the Spice result. These correspond to exceedingly subtle
features in the original data. As an example, consider the small region between 3-4 km and 1.2-1.3 seconds. In the migration
data we see amplitude fluctuations and a bed termination (onlap) up and to the right. The Spice image localizes the
terminating bed and additionally shows the unit above downcutting to form the termination. Interestingly, stratigraphic
intervals are often seen on Spice images to have a bias that associate with interpreted sequence boundaries. This effect is seen
as net brightening or darkening of different stratigraphic intervals.
This example is a small part of one 2D seismic line. Imagine the vast amount of stratigraphic information this
attribute could pull from a 3D data set. An obvious comparison is the stratigraphic detail seen in coherence time or horizon
slices. But coherence does not deliver the kind of vertical stratigraphic image seen in Spice. Spice also offers a different kind of
detail complimentary to state-of-the-art impedance inversion.
Basin floor fans, turbidite deposits, fluvial systems, carbonates, and other stratigraphic targets are of increasing
interest in global seismic search for petroleum. Spice will play a role in this search.
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Figure A shows a panel of migrated data from a 2D
seismic line. These data are from a soft, clastic basin
in Southeast Asia, and are representative of good-quality
marine seismic data world-wide.
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Figure B is the Spice section computed directly from the
migration data. No velocity information is required to
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generate this result. Borehole data can calibrate and validate
the Spice result, but is not required to create it.