Impacts of structuration on slope channel geomorphology and internal architecture: a Pleistocene feeder channel-ponded lobe system, offshore Niger Delta

Impacts of structuration on the geomorphology and internal architecture of a Pleistocene feeder channel-ponded lobe system, Channel-1B (Ch-1B), on the continental slope of the Niger Delta, Nigeria, has been studied using a combination of 3D seismic stratigraphy and geomorphology methods. Mapping of diagnostic seismic facies, characterization of channel morphology and internal architecture, quantitative analysis, architectural element (AE) delineation, and reservoir modeling were carried out with the view to (1) establish Ch-1B geomorphology, internal architecture, and sediment fills, (2) investigate the influence of structuration on the evolution of internal architecture over time, and (3) assess the impact of the resulting internal architecture variability on reservoir modeling and development strategies. This study established a strong link between structuration and the evolution of feeder channel-ponded lobe systems. Evolution of Ch-1B has been summarized in five phases: (I) channel initiation dominated by sediment bypass and incision into fold-1, (II) major break in slope gradient resulting in deposition of ponded lobe-1, (III) complete fill of accommodation created in the ponded basin between folds 1 and 2, diversion of the channel axis westward by fold-2 and eventual incision into lobe-1 and fold-2 by the feeder channel as it adjusted to a new base level, (IV) deposition of lobe-2 in the footwall of fold-2, and (V) filling of the feeder channel, almost entirely, by turbidite muds thereby creating a channel plug that partitioned lobe-1 into two compartments. Understandings, from this work, of the impacts of structuration on geomorphology and internal architecture have been applied to AE delineation, reservoir modeling, and development strategies in terms of the number and type of wells needed to produce hydrocarbon in lobe-1 efficiently. Given that well costs represent a significant portion of field development costs, this study concludes that adequately delineating and modeling structurally influenced AEs will significantly affect field development economics.