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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract:
Subsalt
Turtle Play, Walker Ridge Area,
Deepwater
Gulf
of
Mexico
Subsalt
Turtle Play, Walker Ridge Area,
Deepwater
Gulf
of
Mexico
By
Phillips Petroleum Company, Houston, Texas
The Miocene section under the Sigsbee Escarpment salt in Walker Ridge offers several plays with large reserve potential. Plays include the western edge of the Mississippi Canyon fold-belt trend extending under the salt, large salt pillows showing minor compressional effects, and finally turtle structures that exist upslope and landward from the folds and pillow structures.
Turtle structures formed in Miocene sediments as a result of
autochthonous Jurassic salt withdrawal. Broad elliptical low
areas formed during Late Cretaceous and Paleogene
time, flanked by low-relief salt pillows and ridges. Sand-prone
Early-Middle Miocene turbidite sediments ponded between
the salt highs, accentuating the height of the salt ridges. Collapse
of the flanks of the salt ridges during late h4iocenc time flexed
the edges of the Miocene depocenters creating turtle features.
Large volumes of salt escaped through near-vertical feeders
above the salt ridges forming an extensive, thick, salt canopy system
above the Miocene section. Many of the vertical salt feeders
formed above basement fault trends, indicating an inter-relationship
of the rift geometry and later salt mobilization. During
Pliocene-Pleistocene time, large suprasalt mini-basins developed
above the salt canopy, substantially modifying the
allochthonous salt distribution and masking much of the
subsalt
geometry.
Drilling these structures will be challenging. Water depths range from 6,000 to 7,500 feet. Salt sheet thickness varies from 7,500 to over 20,000 feet. Drilling depths of up to 30,000 feet are necessary to reach the prospective intervals. However, reserve potential is high ranging form 200 to 900 MBOE per structure.
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