The West African Petroleum Systems, Efficiency Key Drivers and Ranking from Continent Scale
Jean-Jacques Biteau, Ghislain Choppin de Janvry, Romain Courel, and Philippe de Clarens
Geoscience, TOTAL, Paris la Défense, France
As it has been evidenced in the past, the efficiency of Petroleum Systems can be calculated from their SPI (Source Potential Index) and from their P.S.Y (Petroleum System Yield) numbers, at Basin and Petroleum Province scale.
P.S.Y numbers are generally found in a range between 30 and 0.1%, most of the world petroleum basins have figures around 1% to a few %. This has been used in house by Total to predict more accurate remaining HC World numbers.
West African Petroleum Systems (Cretaceous and Tertiary) are among the most prolific of the Continent compared to North African platforms (Palaeozoic and Cretaceous P.S).This proven efficiency is mainly pending upon:
The presence of recently functioning petroleum systems (these are effective during Tertiary-Quaternary geological times);
The development of world class source rocks (Bucomazi-Melania-Marnes de Pointe Noire, Iabe, Azile, Turonian…) often developed in stratigraphically well identified condensed levels or rift systems;
The presence of superposed or imbricated sources and plays, probably one of the main drivers;
The efficiency of petroleum systems mainly related to hydrocarbon vertical migration.
This allows in West African specific areas often associated to sand rich fans deposition to observe also efficient stratigraphically controlled traps and then to imagine new plays.
At regional or individual prospect scales in these petroleum provinces where exploration is now at a mature stage or in the frontiers of the Petroleum system occurrences, a key driver is the proximity between the source rocks and the hydrocarbon traps as well as the quality of HC migration pathways.
This means that often coupled with petroleum modelling, we can now utilize well defined, accurate and referenced P.S.Y for different structural trapping contexts in these passive margins, structurally salt or shale gravity driven.
AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery