Abstract: Petroleum Potential and Future Outlook in Angola

Azevedo, Amadeu and José Mangueira - Ministry of Petroleum, Angola

Angola is currently the second largest oil producer in Sub-Saharan Africa with a current production of approximately 730,000 barrels of oil per day. Production is projected to increase to 1 million barrels per day in the year 2000. Advances in technology coupled with a favorable business climate, point to a period of high productivity in the Angolan basins.

The three major coastal sedimentary basins, part of the South Atlantic salt basin, are from north to south the Lower Congo, Kwanza, and Namibe. The Lower Congo and Kwanza basins are oil-producing basins whereas the Namibe basin is currently unexplored. The geologic setting of these basins is similar to that found in more maturely explored sub-basins of the South Atlantic that have large proven reserves. In addition, there are several unexplored interior basins.

The South Atlantic salt basins were initiated with the Late Jurassic to Early Cretaceous rifting of the supercontinent Gondwana. Neocomian to Lower Aptian synrift fluvial clastics and lacustrine shales were deposited during the initial stages of separation of Africa and South America. The early post-rift section is dominated by thick marine evaporites. Carbonates were deposited during the Albian. With continued seafloor spreading during the Tertiary, a thick sequence of shales and turbidite sands were deposited. Within the Lower Congo basin, Oligocene and Miocene deepwater sands currently are the main prospective intervals. Albian carbonates and clastics are primary reservoirs in several areas.

The geology of the Kwanza basin is similar to that of the Lower Congo basin. Albian carbonates may be a very important target within the unexplored deepwater offshore blocks.

Today the Angolan coastal basins are among the highest potential petroleum areas within the Gulf of Guinea. From the 80s until the mid 90s the main target was the Albian carbonate reservoirs of the Pinda Formation with approximately 3 billion barrels of discovered reserves. Advances in deepwater drilling and production technology have allowed exploration of deepwater blocks, and resulted in a change in exploration emphasis.

Deepwater drilling in the Lower Congo basin has increased significantly since 1996. Several giant fields have been discovered recently in the deep water in Tertiary turbidite reservoirs, confirming the high petroleum potential of this play. Reserves are estimated at the moment at more than 4.4 billion barrels. Exploration of deepwater Kwanza basin is just beginning. In the Namibe basin more seismic acquisition is underway to appraise the potential. Some shallow offshore blocks are still open. The unexplored Kassanje, Okawango and Etosha interior basins will be evaluated in the near future.

Invitations to tender have been sent out for several deepwater blocks. The ultra-deepwater offshore of Kwanza basin will be divided in blocks in the near future.

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