Jean Gerard¹, G. Dupont², P.L. Masse², J.M. Moron², D. Pourtoy², R.G. Bromley³
(1) Elf Exploratin Production, Pau, France
(2) Elf Exploration Production
(3) University of Copenhagen

Abstract: From a refined chrono-stratigraphic framework to seismic interpretation : integration of quantitative palynology and micropaleontology, ichnology, sedimentology and seismic from the Lower Congo Tertiary Basin (Angola)

Detailed studies made on both cored and uncored shale-rich facies that separate sand-rich turbidite channel complexes were launched for better constraining the identification of time-lines.

A refined chrono-stratigraphic framework supplies guides for predicting the lateral extent of the seals inside channel complexes and their role in reservoir compartment delineation at the production scale. It helps predicting sand distribution at the exploration scale.

Several techniques closely imbricated support the chrono-stratigraphic chart. Combined quantitative micropaleontological and palynogical studies decipher the record of ecological changes in both sea water and sediments. Epifauna and endofauna respond to physical and chemical changes of the more superficial sediment layers. These changes are often recorded by ichnofabrics too. A combination of these analyses coupled with genetic rules deduced from sedimentological processes inferred from core, log and seismic data, are then interpreted in terms of sediment supply by the paleo-Congo river and sediment storage pattern in the Lower Congo Tertiary basin. Once these results are acquired, they are then tied to seismic data and a series of iterations might be needed.

A reliable chrono-stratigraphic framework is considered to be achieved once coherence between all techniques is gained and the stratigraphic column divided into units bounded by correlative stratal surfaces.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana