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GCThe Use and Abuse
of
Seismic
Attributes*
By
Hans E. Sheline1
Search and Discovery Article #40143 (2005)
Posted March 1, 2005
*Adapted from the Geophysical Corner column in
AAPG Explorer, January, 2005, entitled “Don’t Abuse Seismic
Attributes” and
prepared by the author. Appreciation is expressed to the author, to Alistar R.
Brown, editor of Geophysical Corner, and to Larry Nation, AAPG Communications
Director, for their support of this online version.
1VeriNova, Sugar Land, Texas ([email protected])
General Statement
Seismic
interpretation
is a cornerstone of our industry, as
interpretation
success has grown increasingly dependent on ever-newer combinations of
seismic
attributes (SAs). Attributes are simply defined as information extracted or
computed from
seismic
data
. What combinations work best depend on reservoir
characteristics, the available
data
, and, most importantly, human expertise.
Seismic
attributes
are not magic, but the explosion of 3-D
seismic
at the end of the 20th century
resulted in dramatic increases in the types, combinations, and uses of SAs (Figure
1). We
now have available multi-trace, prestack, horizon, wavelet, and 4-D attributes,
in addition to those derived from shear wave volumes. These allowed for
significant improvements in estimates of reservoir properties from
seismic
(RPFS).
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Figure Captions and Table Caption
General Comments
Table 1 defines terms used in
Unfortunately, the potential for abusing Be wary of pretty SAs that are not well understood. This can damage your credibility while tarnishing the true potential of SAs. Don’t expect your workstation to pop out the solution. Be wary of “black box” answers. Instead, commit the resources to correlate, model, and understand your SAs and what they can and cannot do. Workstations now make it very easy to generate, for example, the third derivative of the instantaneous phase or the second derivative of instantaneous frequency. Even if this SA correlates with ground truth somehow, will you understand it or trust its significance?
Another abused shortcut often sounds like: “Just give me the one
attribute that solves my problem.” In some unusual areas, interpreters
have been able to succeed using only a single attribute
Note in Figure 2 how none of the four
attributes alone shows the sand channel very well – but when they are
combined, the result is both quantitatively and areally more accurate
than any individual attribute. This example shows the dramatic potential
of SAs for lithology prediction. We add value by using experience to
improve estimates of reservoir properties from Therefore, avoid grabbing the first attribute or attributes that seem to work. Instead, develop a robust, efficient work flow that quickly considers many of the most promising attributes and objectively correlates them with seismically scaled and corrected ground truth. Then model these attributes to understand and optimally guide the SA combination to estimate the reservoir properties best and quantify the uncertainty of those estimates.
There is also a real danger of using too many SAs to “over-fit” the
Case History Example
Despite the pitfalls in
Once you have optimized your SAA workflow, it can dramatically improve
property and risk estimates. Robust work flows have been developed on
The speed and accuracy of reservoir modeling and simulation have also been improved using RPFS estimates and associated uncertainty cubes.
Recommendations
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