Integrated Seismic Attribute and Petrophysical Evaluation of Structurally Controlled Hydrocarbon Prospects in the Eastern Niger Delta Basin, Nigeria

Abstract

This study presents an integrated seismic and petrophysical evaluation of structurally controlled hydrocarbon prospects in the Eastern Niger Delta Basin, Nigeria. A high-resolution 3D post-stack time-migrated seismic dataset covering approximately 125 km² was analysed alongside well log data from three exploration wells to delineate structural traps and assess reservoir characteristics. Three key reservoir horizons (H1–H3), occurring between 1850 ms and 2600 ms two-way travel time (approximately 2450–3150 m depth), were identified within fault-assisted closures associated with NE–SW trending growth faults and rollover anticlines. Seismic attribute analysis, including RMS amplitude, instantaneous frequency, acoustic impedance, and sweetness, reveals pronounced amplitude anomalies and low-frequency shadows consistent with hydrocarbon-related effects. Petrophysical evaluation indicates excellent reservoir quality, with porosity ranging from 22.8% to 26.1%, permeability between 1320 mD and 1600 mD, and hydrocarbon saturation averaging approximately 71%. Volumetric estimation yields a Stock Tank Oil Initially in Place (STOIIP) of about 185 million barrels, suggesting significant commercial potential. However, uncertainties related to seismic resolution, lithological effects on amplitude response, and assumptions in petrophysical modelling introduce moderate risk, reflected in a geological chance of success of 0.45. The results demonstrate that integrating seismic structural interpretation, attribute analysis, and quantitative petrophysical evaluation provides a robust framework for reducing exploration uncertainty and enhancing hydrocarbon prospect assessment in structurally complex deltaic systems.