INTEGRATED PETROPHYSICAL CHARACTERIZATION AND HYDROCARBON POTENTIAL ASSESSMENT OF RESERVOIRS IN EMERALD FIELD, NIGER DELTA BASIN, NIGERIA

Abstract

Understanding variations in reservoir quality is essential for evaluating the hydrocarbon potential of the Niger Delta. This study investigated these variations in Emerald Field by integrating petrophysical parameters derived from well logs across six wells: RBK-15, RBK-07, RBK-10, RBK-13, RBK-17 and RBK-04. Gamma-ray, deep resistivity, bulk-density and neutron-porosity logs were analysed using Petrel software to identify reservoir intervals and estimate shale volume, effective porosity, water saturation, hydrocarbon saturation, permeability and net-to-gross ratio (NTG). Water saturation was evaluated using the Simandoux model to account for the influence of shale on resistivity-based estimates. The identified reservoir intervals range from 199 to 266 ft in gross thickness, but their petrophysical properties vary considerably. Mean effective porosity ranges from 0.13 to 0.24, while mean hydrocarbon saturation varies from 0.74 to 0.91 and NTG from 0.55 to 0.83. These differences are reflected in the integrated assessment of the wells. RBK-17 has the most favourable combination of effective porosity, model-derived permeability and NTG, whereas RBK-15 records the highest mean hydrocarbon saturation and lowest mean water saturation. In contrast, RBK-07 exhibits comparatively less favourable characteristics, including higher shale volume and lower effective porosity and NTG. The findings show that reservoir quality in Emerald Field varies between wells and cannot be adequately assessed using a single petrophysical parameter. Integrating these indicators provides a more balanced basis for identifying favourable reservoir intervals and guiding further appraisal. Nevertheless, independent permeability measurements and production data are needed to determine whether the estimated reservoir potential translates into effective production performance.