The Rio Muni Basin: An Emerging Deepwater Hydrocarbon Province

By

Kenny Goh¹, Paul Dailly¹, Phil Lowry¹, Gene Monson¹

(1) Amerada Hess Corporation, Dallas, TX

 The Rio Muni basin underlies the continental shelf of the West African republic of Equatorial Guinea, located between Gabon and Cameroon. The basin is situated above a section dominated by a northeast-southwest trending oceanic fracture zone and its continental extension. This fracture zone constitutes the boundary between the Equatorial Atlantic margin and the West African salt basin.

Despite its location between the prolific hydrocarbon provinces of the Niger delta to the north and the Gabon coastal basin to the south, the Rio Muni basin has been overlooked by the industry for much of the last decade. Previous wells have proved a viable source rock, but no accumulations. Triton Energy licensed Block F & G in 1997 and drilled the Ceiba 1 discovery well in 1999, proving a new hydrocarbon system in the deep water, Late Cretaceous post rift sequence. Deformation by Santonian-Coniacian transpression caused uplift of the shelfal area and deposition of a thick. Slope fan sequence. Contemporaneous salt deformation of rafted deposits and the development of a base of slope compressional belt area also evident. The resultant turbidite sequences form the reservoirs in the Ceiba field. First oil from the Ceiba field was achieved in record time of 14 months. The field has been on production for over a year now and over 20 MMBO have been produced to date. Subsequent exploration drilling focussed by AVO studies has led to the discovery of five new fields in the current play fairway. Future exploration will continue to evaluate the large untested areas of the block.