WOOD, LESLI J.¹, DANIEL PECUCH², BEN SCHULEIN², and MIKE HELTON^3
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