--> Abstract: Evaluation of a Potential Upper-Cretaceous Ultra-Deep Source Rock Basinwards of the Continent-Ocean Boundary from the Congo-Angola Basin, by Zahie Anka, Michel Séranne, Rolando di Primio, Magdalena Scheck-Wenderoth, and Brian Horsfield; #90082 (2008)

Datapages, Inc.Print this page

Evaluation of a Potential Upper-Cretaceous Ultra-Deep Source Rock Basinwards of the Continent-Ocean Boundary from the Congo-Angola Basin

Zahie Anka1, Michel Séranne2, Rolando di Primio1, Magdalena Scheck-Wenderoth3, and Brian Horsfield1
1Section 4.3. Organic Geochemistry, GeoForschungsZentrum Potsdam (GFZ), Potsdam, Germany
2Géosciences Montpellier, Université Montpellier 2, Montpellier, France
3Section 4.4: Basin Analysis, GeoForschungsZentrum (GFZ), Potsdam, Germany

The analysis of several thousand km of 2-D seismic reflection profiles extending from the present-day base of the slope onto the abyssal plain of the Congo-Angola basin, has allowed us to identify a basal seismic unit at about 7.5 to 9 s (twt) depth overlying the Aptian oceanic crust. The unit extends for more than 200 km basinward of the Continent - Ocean boundary (COB) and presents maximum thickness of about 2.5 km at the main depocenter.

This basal unit consists of parallel, continuous, medium-to-high amplitude internal reflections which onlap the oceanic basement. Its upper boundary is represented by a conspicuous, high-amplitude seismic marker, which can be traced throughout most of the basin. Long distance correlation of this marker with wells in the upper slope and shelf suggests a Turonian age. Overlying the unit there are the prograding thick-wedged deposits of the Oligo-Miocene Congo submarine fan.

Despite present-day quite low heat-flow values on the oceanic domain (about 42 ± 3 mW/m2), results from thermal modelling suggests that this basal unit may be currently mature and generating hydrocarbons. Its maturation history and hydrocarbon potential seem to be closely related to the onset and further progradation of the overlying submarine fan deposits. An ultra-deep upper-Cretaceous source rock basinwards the COB of the Congo-Angola basin had not been identified before.

Further generation and migration modelling, as well as comparison to better-known proximal equivalents source rocks, would reveal the relationship between this unit and some of the hydrocarbon seepage features (pockmarks, gas chimneys, sea-bottom oil leakage) documented on the slope of the basin.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery