Geochemical and modeling studies of the Mauritania offshore

Abstract

Geochemical Rock-Eval and visual analyses, as well as modeling studies were carried out in the Mauritania offshore to evaluate its petroleum potential. Analyzed Pliocene to Late Jurassic sediments display generally fair to rich organic carbon contents. Corresponding Rock-Eval source potentials, although often good, are lower than expected from such organic rich rocks, owing to the presence of large amounts of untransformable detrital type IV kerogen associated with the transformable types II and III. Identified sources are numerous, discontinuous and disseminated throughout the stratigraphic section: they are mature when their burial is of more than 2500 m. Maturation modeling (Matoil model) and computation of the quantities of hydrocarbons generated indicate that hydrocarbon generation started in Paleogene times and went on up to Present depending on age, thermal and burial histories of the different sources. Backstripping modeling indicates that traps related to listric faults did not exist in Paleocene times and that part of the generated hydrocarbons could have escaped to the surface near the shelf edge. However, most of the hydrocarbons were generated during or after Mio-Pliocene times and could have been trapped in recently formed structures. Quantitative estimation of generated hydrocarbons and delineation of mature zones made possible to establish priorities between areas to be explored.