Seismic Geomorphology by Spectral Decomposition Volume Interpretation for Basin-Scale Depositional System Delineation, Cuyo Group, Argentina

Abstract

Spectral decomposition analyzes a given signal by the summation of simple, well defined basis functions. The spectral content of seismic data is influenced by the acoustic properties in the Earth, and therefore significant information can be gained from the analysis of the seismic at different frequencies through spectral decomposition during seismic interpretation (Partyka G. et al, 1999). The ability to examine and compare the response at different frequency bands is critical to obtain information that otherwise is difficult to visualize on the full bandwidth data (Chopra et al, 2007). Volumetric RGB (Red-Green-Blue) blend of the optimum frequency cubes (Hall and Trouillot, 2004) rapidly assess and highlight the presence of geological features present in the seismic data. Seismic geomorphology facilitates the study of the subsurface by the extraction of geomorphologic insights from 3D seismic data (Posamentier et al, 2005).

The Cuyo group is an Early to Middle Jurassic siliciclastic sedimentary sequence in the Neuquén basin western Argentina, bounded by two regional unconformities (Intra Liassic & Intra Callovian at base & top respectively) that reaches 2500 meters of thickness and includes several transgressive-regressive cycles associated to thermal subsidence, the paleo-Pacific ocean connection and a continuous contribution of sediments (Dellapé et al, 1979).

3D seismic and chronostratigraphic regional interpretation (nine sedimentary cycles) for the Cuyo Group were conditioned for spectral decomposition, as seismic data quality and interpretation have significant impact in the results. Individual surveys (+20) were analyzed and regionally integrated.

Canyons filled with channels of different geometries and sizes are clearly identified in the slope, while fans are observed in the deep water area. Seismic geomorphology using spectral decomposition volume based interpretation allows the connection of channels in the platform, canyons in the slope and fans in the deep water area used to populate its sedimentary cycle facies maps.

This study demonstrates the added value of spectral decomposition volume interpretation to better delineate the depositional system for the Cuyo Group in Argentina as input to future explorations efforts in the basin.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018