From Seismic Stratigraphy to Seismic Sedimentology: A Sensible Transition
Bureau of Economic Geology, The University of Texas at Austin, Austin, TX
The concept of seismic stratigraphy was developed during the 1970’s on the basis of 2-D seismic technology. Utilizing reflection terminations, configurations and external forms interpreted from multiple seismic profiles, geologists could analyze seismic facies within depositional sequence boundaries and infer regional-scale depositional environments and depositional history.
The introduction of 3-D seismic technology brought dramatic changes to seismic interpretation. In addition to more accurate positioning and geometry control, 3-D seismic data provide crucial information for improving seismic facies analysis: high-resolution horizontal reflection patterns. Seismic sedimentology is the study of depositional lithology, facies, and processes based on the relationships between texture, shape, and trend of horizontal reflection patterns and the morphology of depositional systems.
A major obstacle facing seismic sedimentologists used to be their inability to pick reservoir-scale depositional surfaces that were mostly unresolvable in vertical seismic profiles. This problem has been largely resolved in the stratal slicing technique. Stratal slices from two 3-D seismic volumes in Louisiana illustrate that seismic sedimentology can significantly improve seismic facies analysis by (1) reducing ambiguity in seismic facies mapping and interpretation in seismic stratigraphy, (2) increasing the vertical resolution from the third-order sequence or 100-m level to the reservoir or 10-m level (if the depth is less than 3,000 m), and (3) increasing the vertical sampling for studying high-resolution depositional history, even in wedged and growth-faulted depositional sequences.
AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana