Journal of Petroleum Geology, Vol.10, No.1, pp. 101-114, 1987

©Copyright 2000 Scientific Press, Ltd.

MINERALOGICAL AND GEOCHEMICAL STUDIES OF TERTIARY SEDIMENTS FROM THE EASTERN NIGER DELTA AND THEIR RELATIONSHIP TO PETROLEUM OCCURRENCE

Minapuye I. Odigi*

*Geology Department, Faculty of Science, University of Port Harcourt, PMB 5323, Port Harcourt, Nigeria.

Abstract

Mineralogical and chemical studies have been made of shale cuttings from the Akiri-1 well in Oligocene--Miocene sediments of the Niger Delta. The micromillimeter fraction from the 2,183 to 3,720m stratigraphic interval was analyzed by X-ray diffraction. Kaolinite and chlorite are more abundant than other clay minerals. The illite/smectite composition changes from a phase with 32% illite layers, to one with 82% illite layers over the 3,250 to 3,720m stratigraphic interval. Kaolinite decreased in shallow shales from 22 to 16% and increases to 29% in deep shales. Quartz increases in abundance with depth, while chlorite and plagioclase feldspar show no systematic trend with depth. Calcite is present in small amounts in all the samples.