Structural and Sedimentary Systems in JDZ Block 4 — Implications for Exploration
Avijit Ghosh, Regis J. Drevet, W. C. Boyers, Gokay Bozkurt, Charlton J. Miller, William C. Foley, and J. Schrull
Deepwater Exploration, Addax Petroleum, Geneve, Switzerland
JDZ Block 4 lies 160 Km offshore in the Niger Delta, 30 Km south of the Akpo condensate field, currently under development, in water depths of 1800-2250 metres.
Mapping shows progressively acute West-East thrust belts, propagated upward from the intra-Akata, rotating anticlockwise from North to South within the block toward the grain of the Cameroon Volcanic Line along the eastern margin of the JDZ culminating in highly imbricated and active structures.
Mapping of 3000 Sq. Km. of 3D data across the JDZ tied to well control, followed by attribute analysis and spectral decomposition reveals details of the structural evolution and sedimentary systems from approximately 36.5 Ma to 5.0 Ma.
Large scale basin floor deposystems with easterly to west-south-westerly axes may be clearly observed from the data between 36.5 and 25.5 ma. The Isongo and Cross rivers may have been the primary inputs for these turbidites. These were overlain by large to medium scale canyon cut and fill systems which continued to exploit similar fairways until approximately 15.5 Ma. (Lower to Middle Miocene).
From 13.8Ma to around 10.5Ma. (middle Miocene), the emerging dominance of progressively more northerly transport systems is evident within essentially isopachous sequences deposited in a predominantly mid-slope setting.
From around 8.2Ma (Upper Miocene) inboard sediment loading resulted in the formation and growth of large scale folding and compressional structures at a sub-regional scale as multi-kilometre scale blocks of gravity-driven sediments slid into the deepening Atlantic basin.
Evaluation of the exploration potential of JDZ Block 4 has concentrated on calibrating the mapped seismic facies with well control wherever possible, identifying and classifying reservoir fairways over the block and in synthesizing this analysis with mapping of structural and stratigraphic traps.
AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery