3-D
Poststack
and Prestack Depth Migrated Seismic Data, An
Advanced Interpretive Tool for Subsalt Exploration
William M. House, John A. Pritchett
The recent proliferation of regional, high quality 3-D
seismic surveys in the
Gulf of Mexico has provided a data base which is useful in understanding the
relationships between salt techonics and hydrocarbon systems. Advanced seismic
imaging techniques such as
3-D
poststack
and prestack depth
migration
have
further improved the usefulness of these data. The
3-D
poststack
and prestack
depth migrated data sets allow an interpreter to do much more than simply
produce structure maps below salt. These data also provide a mechanism for
detailed modeling of the subregional tectonoics, and an understanding of how
those tectonics affect parameters such as trap timing, hydrocarbon
migration
and
reservoir development. Correct spacial imaging of the data is provided by these
depth mi ration techniques, allowing a true
3-D
view of salt body geometries.
The depth migrated data also show relationships between salt and subsalt
reflectors at the salt/sediment interface. Evaluation of these data indicates
that the emplacement, and subsequent collapse of allochthonous salt bodies by
salt evacuation, is a process that has dominated the structural and
stratigraphic development of the above salt section in many areas. The timing
and nature of salt sheet emplacement and deformation has also affected the
stratigraphic and structural development below salt. The prestack and
poststack
depth imaging of seismic data below salt allows for the creation of more
accurate geological models of salt sheet emplacement. These models are critical
in evaluating individual prospects. While the odels do not provide unique
solutions, they do allow for the accommodation of all data in assessing risk
with requards to trap timing, hydrocarbon
migration
, and the presence of
reservoir quality sands.
AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995