Abstract: Reevaluation of the Pre-Salt Petroleum System of Cabinda, Angola

J. R. Scheevel, P. Jeronimo, P. Orsolini, V. Barleua

The Pre-Salt sedimentary section of Cabinda, Angola is located in the Lower Congo Basin. The Pre-Salt stratigraphic section consists of lacustrine siliciclastics, and carbonates that predate the extensive Mid-Aptian Loeme Salt. Over 500 MMBO of proven recoverable reserves exist in pre-salt objectives with some individual fields as large as 250 MMBO recoverable.

A reevaluation of Cabinda pre-salt petroleum system based on the extensive available well dataset and recent high-quality 3D seismic surveys has been performed by a four-geoscientist team provided by the JV partners in Cabinda (1. Sonangol, 2. Chevron, 3. Elf Aquitaine, 4. Agip). The group worked for one year at Chevron's facility in San Ramon, California, with technical assistance from specialists in each company provided when necessary.

The petroleum system of Cabinda can be briefly described as follows: (1) Source rocks are Neocomian to Barremian lake-shales with up to 30 % TOC (Excellent reservoirs are Lower Neocomian to Barremian sandstones and/or diagenetically enhanced lacustrine carbonates. Cabinda has the only major production from Lacustrine Carbonates in West Africa. Seals are syn-rift lake-shales or a combination of these shales and salt. Traps primarily result from syn-rift deformation but post-rift basement-involved movements probably also occurred.); and (2) Geochemical analyses show that most of the oil produced from both Pre- and Post-Salt reservoirs have a Pre-Salt source, demonstrating the discontinuity of Loeme salt as a regional seal.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela