--> Plays, Traps and Petroleum Systems in the Deepwater Niger Delta, by O. O. Fadahunsi, S. R. Lawrence, M. Richards, and R. Bray; #90037 (2005)

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Plays, Traps and Petroleum Systems in the Deepwater Niger Delta

O. O. Fadahunsi1, S. R. Lawrence2, M. Richards2, and R. Bray2
1 Energy and Mineral Resources Limited, Lagos, Nigeria
2 Exploration Consultants Limited U.K, Henley-on-Thames, United Kingdom

Exploration in the deep offshore Niger Delta has been ongoing since the mid-1990s. Several important discoveries have been made and as exploration extends into deeper water (>1000 m) exploration strategies have continuously evolved.

In this paper we outline what we believe to be the key aspects of petroleum exploration in the outer reaches of the Niger Delta, Equatorial Guinea and the Nigeria Sao Tome Joint Development Zone.

In geotectonic terms this region extends over the 'shale diapir zone', 'toe-thrust zone' and 'frontal deformation zone' of the distal Niger Delta. Plays are well established as turbidite systems feeding into the deepwater as channels and fans where deposition was at least partially controlled by 'growing' structures (shale diapirs and toe-thrusts). Various combinations of structural and stratigraphic traps are recognised in these settings and play/trap combinations are usually directly delineated as target prospects by 3D seismic interpretation, usually supported by attribute and AVO analysis. However we believe that the difference between success and failure in the extreme deepwater will rely on a deeper understanding of the operative petroleum systems.

The geological basis for this understanding will be:

  • The stratigraphic and geographical distribution of source rocks and reservoirs.
  • The structural evolution, both deltaic and non-deltaic (transform fault interaction) and the control provided on sediment. dispersal (reservoir and source rock development).

The dynamics of the complex petroleum system is strongly influenced by the following:

  • Source rock maturation and overpressures development in the definition of kitchen areas.
  • The plumbing system along-faults and cross-fault migration.
  • Charging of reservoirs and the influence of the tectono-stratigraphic situation (pre-, syn- and post-kinematic).
  • Breaching of traps/seals and remigration of hydrocarbons.