This study presents an integrated seismic attribute and petrophysical approach for reservoir characterization and hydrocarbon prospect evaluation in the X-Field, Niger Delta Basin, Nigeria. The research was undertaken to reduce the uncertainties associated with structural complexity, fault-controlled compartmentalization, and hydrocarbon distribution within the field. While several studies in the Niger Delta have focused independently on structural interpretation or petrophysical analysis, limited attention has been given to the combined application of multi-seismic attributes and quantitative volumetric ranking for improved prospect delineation and uncertainty reduction. The X-Field is located within the extensional tectonic province of the Niger Delta and is characterized by listric growth faults, synthetic and antithetic fault systems, and rollover anticlines that form multiple fault-assisted closures. Interpretation of 3D post-stack seismic data integrated with well logs, well tops, and check shot data led to the identification and correlation of two major reservoir units, RES N and RES O, within the Agbada Formation. Structural interpretation delineated nine prospective closures (A–I) with closure areas ranging from 77.62 to 231.71 acres and gross rock volumes between 4,968.75 and 18,575.58 acre-ft. Petrophysical analysis revealed average net-to-gross ratios of 0.78–0.79, effective porosity values between 0.23 and 0.25, and water saturation ranging from 0.15 to 0.17, indicating generally good reservoir quality across the field. RES N exhibited slightly better reservoir characteristics compared to RES O. Seismic attribute analyses involving RMS amplitude, variance, sweetness, AVO fluid strength, and relative acoustic impedance identified high-amplitude and low-impedance anomalies concentrated around structurally elevated zones and rollover anticlines, suggesting hydrocarbon-charged reservoir sands and effective trap integrity. Deterministic volumetric estimation using formation volume factors of Bo = 1.25 and Bg = 0.8 produced Stock Tank Oil Initially in Place (STOIIP) values ranging from 351, 050.05 to 1, 178, 700.55 BOE and Gas Initially in Place (GIIP) values between 5,171, 361.37 and 19,622,939.84 MSCF. Total Hydrocarbons Initially in Place (HIIP) ranged from 5, 522, 411.42 to 20,801,640.38 BOE, with Prospect A showing the highest hydrocarbon potential, followed by Prospects E and D. The integrated results demonstrate that hydrocarbon accumulation within the field is predominantly controlled by growth fault-related rollover anticlines and fault-bounded structural closures. The study highlights the effectiveness of combining multi-seismic attributes, petrophysical evaluation, and volumetric analysis for improved reservoir characterization and prospect ranking in structurally complex deltaic environments.
Ebong et al. (Mon,) studied this question.