High-Frequency Sequence Stratigraphy from Seismic Sedimentology: A Miocene Gulf Coast Example

Hongliu Zeng and Tucker R. Hentz: Bureau of Economic Geology, The University of Texas at Austin, Austin, TX

Abstract

For high-frequency depositional sequences, seismic-stratigraphic interpretation of vertical seismic profiles commonly generates equivocal sequence boundaries and systems tracts because of poor vertical seismic resolution. To extend well-based high-frequency sequence stratigraphy to a 3-D seismic survey area proves to be a major challenge. We show that critical to such extension is the recognition and interpretation of plan-form geomorphology of depositional systems. Emphasis should be shifted from interpreting vertical seismic data to developing new tools capable of extracting more horizontal, seismic sedimentologic information. This case study of the Vermilion Block 50-Tiger Shoal area, offshore Louisiana, is an example that proportional, stratal slicing between Miocene flooding surfaces provides sequential and accurate seismic imagery of depositional systems, which in turn serves as a basis for recognizing and mapping high-frequency (fourth-order) systems tracts, sequence boundaries, and sequences in a geologic-time domain. In the Miocene interval, most of the fourth-order sequences from wells in the study can be seismically mapped at a resolution equivalent to 10 m in thickness, necessary for accurately reconstructing the high-frequency sequence stratigraphic framework in the region of seismic coverage outside well control.