WOOD, LESLI J.1, DANIEL PECUCH2, BEN SCHULEIN2, and MIKE HELTON3
1Bureau of Economic Geology, The
University of Texas at Austin, Austin, TX
2Pan American Energy, Buenos Aires, Argentina
3Amoco Production
Company, Houston, TX
Abstract: Integrated Seismic
Imaging
and Sequence Stratigraphic Study of Fluvial Reservoir Geometries, San Jorge
Basin, Argentina
A case study in the use of integrated
sequence stratigraphy and seismic
-attributes analysis was performed on
the heterogeneous, Cretaceous-age fluvial reservoirs of the San Jorge Basin
to develop an improved methodology for reducing reservoir-presence risk,
track productive reservoirs, and reduce
interpretation
time. Coherency
was run on the 3-D
data
volume to assist in creating a detailed structural
framework of the field. Sequence-stratigraphic analysis employing well
and
seismic
data
resulted in division of the section into phases of field-wide
channelization and sand development, overlain by alluviation and fine-grained
sediment deposition. First-order unconformities and alluviation flooding
surfaces bounding these cycles were mapped and provided the time-horizon
framework within which to analyze attributes. Analysis of multiple attributes
was performed on the M7 interval that was stratigraphically hung using
the bounding surfaces. Coherency revealed several geometrically sinuous
bodies, effectively defining the potential reservoir containers. Blocky
and bandlimited
seismic
trace inversion was performed on the
data
over
the interval of interest. Results revealed tripartite division of impedance
characterizing the fill within these sinuous geometric features.
Seismic
modeling suggests impedance changes are related to lithologic contrast
between sands and shales. Several wells that were drilled to test these
features encountered thick sands filling erosional lows. However, the erratic
nature of hydrocarbon distribution within these depositional elements suggests
a complex, combined structural/stratigraphic control on hydrocarbon distribution
that requires further study.
AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas