Stratigraphic controls on reservoir quality in the deep-offshore Niger Delta: Integrated sequence-stratigraphic and petrophysical evidence from the ‘BX’ Field

Abstract

Reservoir development in the Niger Delta is affected by geological uncertainties arising from complex stratigraphic architecture, high-frequency sea-level changes, fault-controlled subsidence, and variable sediment supply, which complicate prediction of reservoir geometry, continuity, and quality. This study integrates sequence stratigraphy and petrophysical analysis of the deep-offshore ``BX'' Field, Niger Delta Basin, to define stratigraphic controls on reservoir distribution and quantify properties relevant to hydrocarbon potential and field development. Three-dimensional seismic data and well-log suites from four wells were integrated to interpret sequence boundaries and maximum flooding surfaces and establish Lowstand, Transgressive, and Highstand System Tracts. The interpreted surfaces were correlated with seismic reflectors and diagnostic well-log patterns to constrain facies distribution, sandstone-body geometry, and reservoir architecture. Across interpreted hydrocarbon-bearing intervals, effective porosity ranges from 21.4% to 29.0%, permeability from 3.00 D to 21.49 D, net-to-gross ratio from 0.67 to 0.96, and hydrocarbon saturation from 57.96% to 77.07%. The water-dominated BX-R0 interval in well BX-04, with hydrocarbon saturation of 17.69%, was excluded from hydrocarbon-pay comparisons but retained in reservoir-rock-quality comparisons. Reservoir quality is generally most favourable within Lowstand and selected Highstand System Tracts, whereas Transgressive System Tracts contain more shale and show lower reservoir efficiency. Integrated sequence-stratigraphic and petrophysical evaluation therefore provides a useful basis for reservoir-heterogeneity prediction, reservoir modelling, and development planning in complex deep-water depositional systems of the Niger Delta Basin.