Current
Exploration Status And Future Potential of The
Frontier Basins in The Republic of Mali
Scott, John1 (1) PGA
Consultants, Maida Vale, WA, Australia
For the first time for over 30 years,
exploration is occurring in Mali. The technical basis
for the current activities is presented.
Mali is virtually unexplored
with only semi-regional seismic grids recorded and just 5 exploration wells
drilled.
There are three potential petroleum
systems. The oldest is in the Taoudeni Basin. This play is based on Late
Proterozoic source rocks feeding fractured carbonates
in large anticlines. The source rocks are well exposed on the northern side of
the basin. Major uncertainties remain the timing of generation, and the
development of seals. Positive encouragement is given by gas and condensate
production on test in one well in the Mauritanian sector of the Taoudeni.
The second play is based on Silurian
source rocks, predicted on regional evidence, feeding Palaeozoic
reservoirs. Major unknowns remain the actual distribution of the source and the
timing of generation. This Silurian based system is postulated in both the Taoudeni and the Tamesna basins.
The third potential system occurs in
Mesozoic grabens, part of the Cretaceous to Early
Tertiary series of central Africa. These have proven
commercially productive to the east in Chad and Sudan. Lacustrine
source rocks, the fundamental ingredient, are predicted in the deepest parts of
the half-grabens. Only one exploration well has been
drilled to test this play, in the Gao
Graben of eastern Mali. Oil and gas shows in a
water well near the city of Gao attest to the presence
of a source system, although the extent and volume remain undefined.