Sedimentology and 3-D Seismic Expression of High-Frequency Sequence
Stratigraphy in Miocene, Starfak and Tiger Shoal Fields, Offshore
In Starfak and
Tiger Shoal Fields, the framework of the Miocene sequence stratigraphy
was constructed by wireline log analysis in 150 wells. The extrapolation
of the well-based high-frequency (fourth-order) sequence framework
into the expansive 3-D seismic survey is a major challenge that
requires extracting 10-m geobodies from limited-bandwidth (5-60
Hz) seismic data.
this extrapolation is the recognition and interpretation of high-resolution
depositional features. Emphasis needs to be shifted from interpreting
vertical seismic data to developing new tools capable of extracting
horizontal, seismic geomorphologic information.
This study shows
that proportionally stratal slicing between maximum flooding surfaces
provides sequential and accurate seismic imagery of depositional
systems, which in turn serves as a basis for recognizing and mapping
fourth-order systems tracts, sequence boundaries, and sequences
in the geologic time domain. This presentation 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 31 fourth-order sequences derived from well-log analysis
can be seismically mapped and visualized.
procedure to map a fourth-order sequence includes five steps: (1)
recognize depositional systems on stratal slices, (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
of Economic Geology, The University of Texas at Austin, University
Station Box X, Austin, Texas 78713; e-mail: email@example.com.