Origin of crude oil in eastern Gulf Coast
Analysis of rock and crude oil samples suggests that three source rocks have given rise to most crude oil in reservoirs of the eastern Gulf Coast. Carbonate source rocks of the Jurassic Smackover Formation are characterized by algal-derived kerogen preserved in an anoxic and hypersaline environment, resulting in crude oils with distinct compositions. Migration commenced during the Cretaceous, explaining the emplacement of Smackover-derived crude oil in Jurassic and in some Cretaceous reservoirs. Upper Cretaceous clastic and carbonate source rocks are also present. Much crude oil in Upper Cretaceous reservoirs has been derived from organic-rich marine shales of the Tuscaloosa Formation. These shales are characterized by algal and higher plant kerogen, resulting in distinct crude oil compositions. Migration commenced during the Tertiary, but was mostly focused to Upper Cretaceous reservoirs. Lower Tertiary shales, including those of the Wilcox Formation, are quite organic-rich and include downdip marine facies characterized by both algal and higher plant kerogen. Crude oils in lower Tertiary reservoirs are dissimilar to crude oils from deeper and older source rocks. Migration from lower Tertiary shales commenced during the late Tertiary and charged Tertiary reservoirs. Although most crude oil in the eastern Gulf Coast has been emplaced by short-range migration, often with a strong vertical component, some long-range lateral migration (>100 km) has occurred along Tertiary sands.
- OSTI ID:
- 6084022
- Report Number(s):
- CONF-880301-
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ATLANTIC OCEAN
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CARBONATE ROCKS
CARIBBEAN SEA
CENOZOIC ERA
CHEMISTRY
COMPARATIVE EVALUATIONS
CRETACEOUS PERIOD
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGY
GULF OF MEXICO
JURASSIC PERIOD
KEROGEN
MATERIALS
MESOZOIC ERA
MIGRATION
MINERAL RESOURCES
ORGANIC MATTER
ORIGIN
PETROLEUM
PETROLEUM DEPOSITS
PETROLEUM GEOLOGY
RESOURCES
ROCKS
SEAS
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
SURFACE WATERS
TERTIARY PERIOD