Petroleum Potential of the Congo Basin - Geology and Resource Potential of the Congo Basin - page 358

18

Petroleum Potential of the Congo Basin

Damien Delvaux and Max Fernandez-Alonso

18.1 Introduction (e.g. Daly et al. 1992 ). This caused depositional hiatus, uplift

and erosion periods, faulting and folding, leading to the
development of stratigraphic and tectonic unconformities
(e.g. Kadima et al., Chap. 6 , and Linol et al., Chap. 11 ,
this Topic).
Although the petroleum potential of this ca. 1.2 million
km 2 intra-continental basin has been of interest for decades
(Misser 2013 ), the CB is still one of the largest, least well-
understood basin in the world due to relatively limited obser-
vational data. Only two stratigraphic wells and two deep
petroleum wells have been drilled since exploration began
in the 1950s. Many important aspects of its geological knowl-
edge and petroleum systems remain poorly constrained, such
as: its regional tectonic framework and internal structure, the
stratigraphy of the basin fill, potential source rock levels,
reservoirs and seal facies, its burial and thermal history, and
so forth. Despite this, the CB is considered by some as a new
future petroleum province (e.g. Mello 2008 ; Pilipili Mawezi
( 2010 ). Here, we re-evaluate the petroleum potential of the
CB in light of geochemical data from both academic and
industrial sources.

The Congo Basin (CB) is a broad and long-lived intra-
cratonic depression in the centre of the African Plate cover-
ing most of the Democratic Republic of Congo (DRC,
formerly Zaire), the People s Republic of Congo and the

Central African Republic (CAR), coinciding with a region
of pronounced long-wavelength gravity anomaly (Crosby
et al. 2010; see also Raveloson et al., Chap. 1 , this Topic).
The CB has a long (~600 Ma) and complex history of
sediment accumulation, tectonic inversion and erosion
since the end-Neoproterozoic (Veatch 1935 ; Cahen 1954 ;
Cahen and Lepersonne 1954 ; Lepersonne 1974 , 1977 ; Daly
et al. 1992 ; Giresse 2005 ; Kadima et al. 2011a ; see also
Kadima et al., Chap. 6 , this Topic), and it was affected by
the break-up of Gondwana during the Mesozoic (Torsvik
and Cocks 2011 ; see also Linol, Chap. 11 , this Topic).
Today, the CB is still tectonically active along the East
African Rift margin (Delvaux and Barth 2010 ).
The CB contains up to ~9 km of Neoproterozoic, Paleo-
zoic and Meso-Cenozoic sedimentary sequences (Kadima
et al. 2011a ; and Delpomdor et al., Chaps. 3 , 4; Linol et al.,
Chaps. 7 - 9 ; Kadima et al., Chap. 6 , this Topic). The basin is
believed to have initiated as a Neoproterozoic rift and a large
part of its subsequent subsidence history has been modelled
by post-rift thermal relaxation (Kadima et al. 2011b ; Buiter
et al. 2012 ; Lucazeau et al., Chap. 12 , this Topic; but see Linol
et al., Chap. 11 , this Topic, for alternative models). Global
climate change, Gondwana motions and break-up, and intra-
plate stresses are the main factors that controlled the tectono-
stratigraphic evolution of the CB. Several tectonic inversions
occurred during its Phanerozoic development as a response to
far-field compressional stresses generated at plate boundaries

'

18.2 History of Petroleum Investigation

As early as the beginning of the twentieth century, Cornet
( 1911 ), then Passau ( 1923 ) recognized that the CB
(Fig. 18.1 ) contains organic-rich rocks with potential for
oil and gas. The first exploration project was performed
between 1952 and 1956 (Mission REMINA— Syndicat
pour l' ´tude g ´ologique et mini`re de la cuvette congolaise ),
with geological field investigations, combined gravity and
magnetic measurements, 600 km of refraction seismic
profiles, 131 km of seismic reflection profiles, and two
~ 2,000 m deep fully cored stratigraphic wells (Samba and
Dekese). The results have been largely published in the
Annales of the Royal Museum for Central Africa (RMCA),
in Tervuren, Belgium, where outcrop samples and cores are
also archived.