Abstract: Cameroon Rio Del Rey: The "Great Ekundu" Fields--A Model for Intensive Exploration in Deltaic Provinces

Francois Nguene

The "Great EKUNDU" fields are located offshore Cameroon in the Rio Del Rey, an area which comprises the eastern part of the Niger delta. Water depths range from 6 to 20 m.

The first discovery was made in 1972. Since then, ELF SEREPCA, a subsidiary of ELF AQUITAINE, and its partners SHELL-PECTEN and SNH have discovered 25 fields in what is called the EKUNDU Concession (170 sq km). The initial reserves are approximately 350 MMbbl (50 million tons) of oil, an amount which represents about half the total reserves of Cameroon.

The "Great EKUNDU" fields are associated with structural traps which formed in response to diapiric activity and the formation of shale ridges in a deltaic environment. The traps are highly faulted and very complex. Reservoirs and seals are sands and shales of the Upper Miocene. Hydrocarbons in the traps (both oil and gas) have been found under different pressure ranging from hydrostatic to 14.5 ppg equivalent mud density. Reservoirs, encountered between 1100 and 2000 m, have porosities ranging from 28 to 36%. The oils, with gravities ranging from 21 to 45° API, were sourced from Eocene to lower Miocene shales (type III kerogens). In general, drainage areas are controlled by the shale ridges and traps were charged through the fault systems. Recovery can be up to 70 % when the wat r drive is very efficient.

Interpretation of seismic amplitude anomalies has been a good guide for exploration and appraisal. A good data base and the use of multidisciplined studies and techniques (including drilling, geology, geophysics / 3-D seismic,

reservoir engineering and platform design) have led to the discovery and production of smaller fields like NYANGASSA NORTH and ITINDI.

These techniques can be extrapolated to other deltaic prospects both in Rio Del Rey and the Eastern part of Nigeria.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994