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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Salt Kinematics, Depositional Systems, and Implications for Subsalt Hydrocarbon
Exploration, Eugene Island and Ship Shoal South Additions, Offshore Louisiana
By
Excalibur Interpretation Company, Houston
Detailed interpretation and mapping of more than 10,000 km of 80-fold 8-second recent seismic data, and preliminary interpretation of 2500 km of new 15-second, 6-km streamer data provide a new understanding of the kinematic and stratigraphic development of the southern Louisiana shelf. The new data reveal elongated basins below horizontal salt sheets or evacuated horizontal salt welds. These basins are separated by nearly vertical salt welds and residual salt walls. Sequential back-stripping of balanced depth sections suggests that the walls grew primarily by down-building. Sand fairways developed between the salt walls with a primary sediment transport direction from the northeast to the southwest.
The overlying strata are characterized by
backward
-rotated hanging walls overlying
listric growth-faults. We propose that the
original extent of salt sheets emplaced near
the sea floor can be defined by the current
location of the extended overburden that
formed as a result of secondary salt-sheet
withdrawal. Windows through the residual
salt, horizontal salt welds, and a few key
deep wells that have penetrated the welds
provide biostratigraphic control on the timing
of the salt/sediment interactions. The
vertical welds and walls, coupled with residual
salt sheets and horizontal welds,
form a network of surfaces separating
largely isolated basins. Each basin seems
to have developed independently by various
episodes of local salt motion. The Mahogany
discovery, Ship Shoal 349, is an
example of sands trapped against the flank
of a northeast-trending nearly vertical salt
weld. Maps of the former salt sheets associated
with salt walls and welds, and maps
of subsalt structure below the sheets and
welds define prospective areas analogous
to Mahogany. Additional attractive structures
were also localized by salt-sediment
interactions.
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