Recognizing Environments in the Deposits of the Niger Delta
OBOH, FRANCISCA EMIEDE, University of Cambridge, Cambridge, U.K.
The paralic sediments of the Agbada Formation are the targets of commercial exploration and exploitation of oil and gas in the Niger delta. Sedimentological and microfossil data from a middle Miocene reservoir in the delta have revealed a succession of deltaic subenvironments of deposition within a prograding offlap sequence.
Ten lithofacies, comprising five sandstone, three heterolithic, and two mudstone types, are recognized from grain size, sedimentary structures, and trace fossils in two cored boreholes. Fourteen palynodebris types, including amorphous organic matter, various types of palynomorphs, and wood, were identified in the sediments. These components were subjected to principal component analysis and cluster analysis. The resulting palynofacies are integrated with lithofacies and paleoecological inferences made from the palynomorph and foraminifera contents of the sediments for paleoenvironmental reconstruction. Gamma-ray log correlation of the reservoir in uncored boreholes was carried out, using information from the cores, and this has resulted in a depositional model.
AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)