Identification of organic-rich lower tertiary shakles as petroleum source rock, southern Louisiana

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

OSTI ID:7135447

McDade, E C ^[1]; Sassen, R ^[2]; Wenger, L ^[3]; Cole, G A ^[4]

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1. Texaco Inc., New orleans, LA (United States)
2. Texas A M Univ., College Station, TX (United States)
3. Exxon Production Research, Houston, TX (United States)
4. Saudi Aramco Laboratories Department, Dhahran (Saudi Arabia)

Comprehensive organic geochemical evidence of organic-rich, marine shales in the lower part of the middle eocene Claiborne Group and the lower Eocene-Paleocene Wilcox Group of southern Louisiana is now available. The evidence influences models for Gulf Coast petroleum origin. The shales are the only post-Cretaceous sediments in the northern Gulf of Mexico that meet recognized criteria for oil source rocks. Many of organic-rich Paleogene shales contain terrestrially derived, amorphous kerogen altered by microbial activity, and display pyrolysis results consistent with type II/III kerogen. Shelf-edge depositional environments favored preservation of hydrogen-rich kerogen. Seismic and sedimentologic interpretations suggest that marine character and thickness increase on the Paleogene continental slope to the south. The shales at burial depths in the 3050-4600 m depth range, at present, are thermally immature to late mature with respect to oil generation. Detailed geochemical analyses of extractable organic matter and kerogen isolates suggest an oil-source correlation with Tertiary-reservoired oils in southern Louisiana and offshore in the adjacent Gulf of Mexico. Biomarkers of selected samples display high concentrations of C[sub 28]-bisnorhopane and 18[alpha]-oleanane biomarker is absent or not reported in Gulf crude oils from Cretaceous and Jurassic source rocks. Burial and thermal history models suggest the timing of oil migration from Paleogene source rocks is consistent with emplacement of oils in Tertiary reservoirs. The lower Tertiary source rocks described here could offer new insight to understanding the origin of oil in other Tertiary deltas.

• OSTI ID: 7135447
• Report Number(s): CONF-9310237--
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 77:9; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
ATLANTIC OCEAN
CARIBBEAN SEA
CENOZOIC ERA
CHEMISTRY
CONTINENTAL MARGIN
CONTINENTAL SLOPE
DEVELOPED COUNTRIES
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GULF OF MEXICO
JURASSIC PERIOD
LOUISIANA
MESOZOIC ERA
MINERAL RESOURCES
NORTH AMERICA
ORIGIN
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCES
ROCKS
SEAS
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
SURFACE WATERS
TERTIARY PERIOD
USA