Subkinematic and growth strata sequences in the deepwater Niger Delta – Insight from OPL 250

Abstract

Six sub-kinematic and three growth strata sequences have been described from the deepwater Niger Delta region using seismic and well log data sets from oil and gas industry. The goal was to create a preliminary overview and a base framework for tracking stratigraphic sequences within the study area. The sub-kinematic sequences (Ks1 – Ks6) are third order sequences with time span ranging from 1 to 2 million year (Ma). Possibly three fourth order sequences occur in Ks5. From log signatures, the sequences generally consist of thick hemi-pelagic shales interspaced with thin sand prone intervals. The sand prone intervals represent gravity slump deposits such as basin flow fans and sand flushed from channels mouths at the onset of the lowstand system tract (LST). Growth strata sequences consist of thick hemi-pelagic sections with deeply incised channels and associated levee systems and possibly extensive reworked sand prone facies. Vertical communication is enhances due to stacking of sand prone facies. Thrust initiation at 12.8 MA defines the boundary between charged sands in deeper sections and water filled sands in shallow section.