Techniques for Imaging 4th- and 5th-Order Shelf Sequences in 3-D Seismic Data: Miocene, South Texas Gulf Coast
The search for economically viable hydrocarbon prospects increasingly requires exploration of morphologically complex features at the limit of seismic resolution. Imaging techniques, such as spectral decomposition, that exploit the large frequency spectrum of modern 3D seismic data can facilitate identification of potential reservoirs easily missed during single line/trace interpretation. This study demonstrates that combining frequency decomposition with extracted geophysical attributes can successfully delimit 4th- and 5th-order sequences in Miocene strata of the South Texas Gulf Coast. A detailed workflow is described that corroborates the advantages of interpreting discrete frequency volumes generated using spectral decomposition, as opposed to conventional seismic data. Transforming data into this format facilitated interpretation of major 3rd-order, Miocene sequence boundaries in map view, where geomorphology is better observed because of the lateral impedance variability associated with such unconformities. As a result, sequence boundaries were picked with a high degree of accuracy and validated with well data so that a preliminary stratigraphic model could be constructed for identifying likely channel-bearing intervals. By constraining the interval of frequency decomposition to accurately mapped sequence boundaries, decomposition parameters were refined to expose 4th- and 5th-order channels and incised valleys not apparent in the original data. Using this method, we could infer a detailed stratigraphic history in which production within the seismic survey could be attributed to specific, contemporaneous channels in an otherwise inchoate stacked-channel environment. Without our employing such techniques, the complexity of this environment would have gone unappreciated, making rigorous seismic stratigraphic interpretation difficult.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009