Zeng, Hongliu, Hentz, Tucker F., and Wood, Lesli J.

Bureau of Economic Geology, The University of Texas at Austin, Austin, TX

Extracting high-resolution information from limited bandwidth seismic data is a major challenge when using seismic to extend well-based high-frequency sequence stratigraphy to a 3-D area. Critical to such extension is the recognition and interpretation of a geobody's plano-form. Emphasis should be shifted from interpreting vertical seismic data to developing new tools capable of extracting more horizontal, seismic sedimentologic information. This case study shows that proportionally, stratal slicing between 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 geologic time domain. This example illustrates why stratal slices are generally better than time slices and horizon slices in interpreting depositional morphology. In a 1-s-traveltime interval, most of the 31 fourth-order sequences from wells in the study can be seismically mapped at a resolution equivalent to 10 m in depth. An easy-to-follow procedure to visualize a fourth-order sequence by using stratal slices includes five steps:

1. recognize depositional systems,
   
   
2. separate mapping units by viewing depositional history,
   
   
3. digitize systems tracts,
   
   
4. visualize systems tracts and sequence boundaries in geologic time, and
   
   
5. visualize systems tracts and sequence boundaries in depth (traveltime).