Upper tertiary/quaternary detachment surface, Gulf Coast of Texas and Louisiana

Conference · Wed Sep 01 04:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6964501

Brooks, R O ^[1]

---

1. TGS-CALIBRE Geophysical Company, Houston, TX (United States)

Over the past five years, deep seismic resolution in the Gulf of Mexico has improved to the point that extensive horizontal salt bodies have been defined and initial drilling has commenced for subsalt reservoirs. This enhancement of the deeper seismic also shows evidence of a related deep and extensive decollement surface or unconformity that divides the geologic section into two separate but very different structural realms. Upper Pleistocene to Miocene sediments are mixed sand and shale, extensively structured by movements of mobile salt/shale and numerous listric growth faults that generally flatten with depth along a common decollement or detachment surface. Below the decollement zone from 15,000 to over 25,000 ft Lower Miocene through Oligocene mostly shaly sediments exhibit more limited structuring and high-angle faults. Most of the horizontal salt injection on the southern Louisiana shelf occurred within the thick deep-water shales that postdate this surface. Later loading by Pliocene-Pleistocene sands and shales caused extensive additional salt movement. Penetrations into the deeper zones are limited, but include wells in Louisiana, South Marsh Island, and Main Pass. The age of the surface varies from early Miocene to late Eocene and is seismically defined by the flattening of overlying listric faults, discordant dips that in some cases appear as angular unconformities, and higher amplitudes along salt surfaces. The exploration potential is currently questionable due to depth, abnormal pressures, and risk of reservoir sands. There is considerable work to be done, however, toward understanding the relationships to hydrocarbon migration, Pliocene-Pleistocene depositions, and overlying structuring.

• OSTI ID: 6964501
• Report Number(s): CONF-9310237--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 77:9
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
ATLANTIC OCEAN
CARIBBEAN SEA
CENOZOIC ERA
DEVELOPED COUNTRIES
EXPLORATION
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
GULF OF MEXICO
HYDROCARBONS
LOUISIANA
MIGRATION
NORTH AMERICA
ORGANIC COMPOUNDS
PLEISTOCENE EPOCH
PLIOCENE EPOCH
QUATERNARY PERIOD
RESERVOIR ROCK
ROCKS
SEAS
SEDIMENTARY ROCKS
SEDIMENTATION
SEISMIC SURVEYS
SHALES
SURFACE WATERS
SURVEYS
TERTIARY PERIOD
TEXAS
USA