Abstract: Petroleum System Modeling in Congo: the Moho-Nkossa Case

Brigaud, Frederic and Denis Levache - Elf E&P

A study has been conducted in the Congo coastal basin for assessing the Moho-Nkossa petroleum system behavior which has both syn-rift and post-rift components. It illustrates the impact of the geodynamic evolution from a rift system to a passive margin on the HC generation and migration as well as the switch from the "classic" congo system to the tertiary petroleum system.

The objectives are to address the timing of HC generation from pre-salt and post-salt source rocks, and to describe the mechanisms controlling the migration and entrapment of generated hydrocarbons using a TEMISPACK 2D numerical approach. The cross-section runs trough the Nkossa and Moho structures.

Eventually, we focused our analysis on the faults located on both sides of the Moho structure. Their timing of opening and closure provide a guideline for their permeability history that was used for simulating a likely mechanism of vertical migration from source rocks in the trenches towards the shallow Pliocene sands.

This method provides an opportunity to perform a basin scale analysis in an integrated dynamic context. It also allows us to test various hypotheses and to highlight the sensitive parameters controlling the HC generation-migration history. Although, this 2D approach does not provide a quantitative insight of the system, it permits us to focus on the most likely scenarios for timing of HC generation, migration and entrapment.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil