Seismic
Facies Analysis of Lacustrine System: Paleocene
Upper Fort Union Formation, Wind River Basin, Wyoming
Louis M. Liro, Yvonna C. Pardus
We interpreted seismic
reflection
data
, supported by well control, to
reconstruct the stratigraphic development of Paleocene Lake Waltman in the Wind
River basin of Wyoming.
After dividing the upper Fort Union into eight seismic
sequences, we mapped
seismic
attributes (amplitude, continuity, and frequency) within each sequence.
Interpretation
of the variation in
seismic
attributes allowed us to detail delta
development and encroachment into Lake Waltman during deposition of the upper
Fort Union Formation. These deltas are interpreted as high-energy,
well-differentiated lobate forms with distinct clinoform morphology on
seismic
data
. Prograding delta-front facies are easily identified on
seismic
data
as
higher amplitude, continuous events within the clinoforms.
Seismic
data
clearly
demonstrate the time-transgressive nature of this facies. Downdip of these
clinoforms, homogeneous shales, as evidenced by low-amplitude, generally
continuous
seismic
events, ac umulated in an interpreted quiet, areally
extensive lacustrine setting.
Seismic
definition of the lateral extent of this
lacustrine facies is excellent, allowing us to effectively delineate changes in
the lake morphology during deposition of the upper Fort Union Formation.
Encasing the upper Fort Union lacustrine deposits are fluvial-alluvial deposits,
interpreted from discontinuous, variable-amplitude
seismic
facies.
We highlight the correlation of seismic
facies
data
and
interpretation
to
well log
data
in the Frenchie Draw field to emphasize the accuracy of
depositional environment prediction from
seismic
data
.
AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.