Lower Congo Basin Turbidites Challenges: Fulfilling Current Activities and Preparing the Future

Jean Jacques Jarrige¹ and Jean-Jacques Biteau^2
1 TotalFinaElf, Paris la Defense, France
² Total, Paris, France

During the last decades, the Exploration of turbiditic systems plays in the Lower Congo-Gabonese Basins has concerned two different petroleum systems and was developed in two major stages:

• The Upper Cretaceous or Senonian P. S. was discovered on the shelf as early as the 1960's in the Gabonese offshore Senonian Basin.
• The deepwater labe- Tertiary P.S. was defined later on by the Bengo discovery in 1994, although Tertiary small fields or shows were evidenced in the 1970's on the shelf domain). It was confirmed as a prolific system by the discovery of Girassol in 1996.

These two rich and efficient petroleum systems are related to high migration efficiency ratios enhanced by superposed or imbricated sources and plays and a vertical driven drainage.

The Tertiary plays are experiencing several stages of activity associated with specific challenges:

• developing major discoveries with recent technologies at the lowest costs
• carrying out the delineation and evaluation of the residual potential of mature acreage
• valorizing small discoveries by new concepts and innovative technology
• exploring blocks in ultra-deep water domains, where conditions of the petroleum system efficiency may change.

In block 17, Girassol has been producing since November 2001, Jasmim was tied back in December 2003 and Dalia is to start up in 2006 at a rate of 225 Kbbl per day. These fields illustrate the challenges which have been faced in terms of static and dynamic reservoir modelling after only a moderate delineation effort helped by a very consistent seismic imagery.