Structural characterization and interpretation of 3d seismic data in the rnd field, offshore Niger delta, Nigeria

Abstract

The RnD Field lies at the Coastal Swamp to Offshore Depobelt boundary of the Niger Delta in southern Nigeria and covers 143.5 km². A three dimensional post stack time migrated seismic volume was interpreted in Petrel to characterise the structural framework, to delineate seismic facies, and to identify petroleum traps. Thirty two faults were mapped, comprising five major and twenty seven minor structures that express growth, structure building, back to back, antithetic, and counter regional styles, a diversity that reflects the dual depobelt setting of the field. A well to seismic tie at RnD-01, using a zero phase Extended White wavelet convolved with calibrated sonic and density logs, identified three Agbada Formation reservoir horizons, R1, R2, and R3, at average depths of -5,070 ft, -5,300 ft, and -6,600 ft respectively. Three seismic facies were delineated: Facies I of chaotic Akata shales, Facies II of parallel high amplitude Agbada reservoir sands, and Facies III of arched reflections within structural closures. Anticlinal closures were defined within both R1 and R2, comprising four way, two way, three way, and rollover geometries, while a combined structural and stratigraphic trap associated with a lenticular high amplitude channel anomaly was recognised adjacent to fault F8. Amplitude brightening within the back to back closure on Inline 3873 constitutes a candidate direct hydrocarbon indicator that warrants amplitude versus offset analysis. The western R2 four way closure and the back to back fault closure are ranked as the priority exploration targets.