The Challenges of Hydrocarbon Exploration in Deepwater Complex Salt Cored Fold and Thrust Belt, Block 31, Angola
Geoffrey S. Hill1, Ilidio Domingoes Silva2, and Andrew Los1
1 BP Exploration Operating Co Ltd, Sunbury On Thames, United Kingdom
2 Sonangol, Luanda
Deepwater Block 31, offshore Angola is dominated by near surface allochthonous salt bodies as part of a canopy which overlies and is part of a fold and thrust belt in the Lower Congo Basin. Variations in fold style and salt canopy development are observed. Elongated folds and thrusts with individual salt canopies host the discoveries of the east, whilst the west is structurally more complex with large, opposing fore and back-thrusts and amalgamated salt canopy extrusions. Accurate trap definition has been and remains a key determinant of exploration success in both extra and sub-salt areas.
The group has embarked on an imaging program capitalizing on experience in the Gulf of Mexico. The seismic data has been processed conventionally, and enhanced by pre-stack time migration to optimise extra salt attributes.
Additionally pre-stack depth migration using a combination of existing and Wave Equation and Kirchhoff seismic processing techniques has been applied. These techniques show the prospectivity over much of the block. Finally the group is acquiring new seismic data, specifically designed to image in the most difficult parts of this challenging block.
The group, with the strong support of Sonangol, believes that by continuing to apply and develop the best technology to optimise the data for exploration and working to solve the many issues around development in these water depths, that this new salt frontier play can be successfully exploited in Africa.