From Seismic
Stratigraphy to
Seismic
Sedimentology: A Sensible Transition
H. Zeng
Bureau of Economic Geology, The University
of Texas at Austin, Austin, TX
The concept of seismic
stratigraphy was developed during the 1970’s
on the basis of 2-D
seismic
technology. Utilizing reflection
terminations, configurations and external forms interpreted from multiple
seismic
profiles, geologists could analyze
seismic
facies within depositional
sequence boundaries and infer regional-scale depositional
environments and depositional history.
The introduction of 3-D seismic
technology brought dramatic
changes to
seismic
interpretation. In addition to more accurate positioning
and geometry control, 3-D
seismic
data provide crucial information
for improving
seismic
facies analysis: high-resolution horizontal
reflection patterns.
Seismic
sedimentology is the study of
depositional lithology, facies, and processes based on the relationships
between texture, shape, and trend of horizontal reflection patterns
and the morphology of depositional systems.
A major obstacle facing seismic
sedimentologists used to be their
inability to pick reservoir-scale depositional surfaces that were mostly
unresolvable in vertical
seismic
profiles. This problem has been
largely resolved in the stratal slicing technique. Stratal slices from
two 3-D
seismic
volumes in Louisiana illustrate that
seismic
sedimentology
can significantly improve
seismic
facies analysis by (1)
reducing ambiguity in
seismic
facies mapping and interpretation in
seismic
stratigraphy, (2) increasing the vertical resolution from the
third-order sequence or 100-m level to the reservoir or 10-m level
(if the depth is less than 3,000 m), and (3) increasing the vertical
sampling for studying high-resolution depositional history, even in
wedged and growth-faulted depositional sequences.
AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana