Journal of Petroleum Geology, Vol.6, No.2, pp.207-216, 1983

©Copyright 2000 Scientific Press, Ltd.

PETROLEUM GEOCHEMISTRY OF LATE CRETACEOUS AND
EARLY TERTIARY SHALES PENETRATED BY THE AKUKWA-2
WELL IN THE ANAMBRA BASIN, SOUTHERN NIGERIA+

Chukwuemeka M. Ekweozor* and James R. Gormly**

+Presented at the 23rd Annual Conference of the Science Association of Nigeria, Benin, April 1982.

*Department of Chemistry, University of Ibadan, Ibadan, Nigeria.

**Institutfur Erdol und Organische Geochemie (ICH-5) Kernforschungsanlage Julich GmbH, Postfach 1913, D-5170 Julich, FR Germany.

Abstract

The concentration, type and thermal maturity of organic matter from the Imo Shale, Nkporo Shale and the upper parts of the Nkalagu Formation which were penetrated by the Akukwa-2 well are presented. The organic carbon content ranged from 0.4-3.5%. The kerogens from the various formations were of the humic and mixed varieties. Evidence from independent thermal maturity parameters (namely, average vitrinite reflectance (Ro%), Tmax and transformation ratio from Rock-Eval, n-alkanes distribution pattern, and hopane "fingerprint") combined to locate the top of the "oil window" within the Nkporo Shale at a depth of approximately 2,000 m from the surface. This corresponds to a threshold temperature circa 65°C.