『Abstract
The presence of rocks capable of generating hydrocarbons (HC)
in the section of sedimentary-rocks basins is an essential criterion
for their qualification as structures with oil and gas pools.
Although organic matter (OM) is always present as dissemination
in genetically different sediments, it is believed that rocks
enriched with OM of the sapropel series (2 to 3 % Corg)
can generate a significant amount of liquid HC. However, rock
sequences with the Corg ranging from 3-5
and 15-20 % are considered oil source formations. The rock section
of large petroliferous basins usually includes one or two source
sequences, which generated liquid and gaseous HCs after submergence
to high temperature and pressures zones. In the basin confined
to the Arctic slope of Alaska, one of the main producers of liquid
HC is represented by the Upper Triassic clays and limestones of
the Shublik Formation. In the Barents Sea and North Sea basins,
such rocks are represented by the Spekk Formation and the Kimmeridge
Clay, respectively; in the West Siberian basin, by the Bazhenovo
Formation; in the Persian Gulf, by the Fahlian, Sargelu, and Garau
formations; in basins of the Caribbean region, by marls and clayey
limestones of the La Luna Formation. In perioceanic basins of
the South Atlantic, the major source sequences are represented
by the Neocomian and Barremian clays and marls. The source rocks
are identified as the Lagoa Feia Formation in the Campos and Santos
basins. They are cognized as the Black Marlstone or Bukomazi Formation
in the Lower Congo, Kwanzaa-Cameroon, and Angola basins.』
Early and middle Triassic epochs
Late Triassic and early Jurassic epochs
Late Jurassic-Berriasian
Neocomian-Aptian
Conclusions
References