The hydrocarbon habitat of the Agadir basin offshore Morocco

Truempy, D. M., and S. C. Reeve, Shell International E & P Deepwater Services, Houston, TX

Abstract

In 1998, Shell acquired 2000 km of 2D seismic in the Agadir deep water basin, where previous exploration had revealed a mobile salt substratum in an area characterized by the presence of a world class source rock (the Cenomanian-Turonian Tarfaya Shale). On the Jurassic carbonate and Cretaceous clastic shelf, significant oil shows have been also discovered during the seventies.

Key results of the 1998 to 2000 Agadir basin exploration are:

1. The Agadir basin is highly structured, due to interaction of the Atlas orogeny and passive margin halokinesis. This structuring creates a large number of potential traps.
2. An Atlas-sourced fluvial system delivers Tertiary turbidites to the basin. A Cretaceous delivery system from a more southerly source is expected to contribute older turbidites into the same area. Erosional scours originating on the platform confirm that the Cretaceous shelf sands have also been transported into the basin.
3. Geochemical modeling, supported by the shows in platform wells and abundance of oil seeps, suggests that an active oil charge system is working in the basin. The world-class Tarfaya Shale is likely to be mature over large areas. Older source rocks are likely to further contribute to oil (and gas) charge.

Based on the results of the reconnaissance phase, Shell has converted their reconnaissance licenses into formal exploration permits. This notwithstanding, substantial risks remain which will be addressed in the 2001 campaign. Most prominently, reservoir quality is a concern in an area where carbonate rocks abound in the source area. In addition, the young age of halokinetic activity is a critical factor for trap integrity.