Structural and stratigraphic mapping of Emi field, offshore Niger Delta

Abstract

The Niger Delta, where oil and gas are predominantly trapped in sandstones and unconsolidated sands in the Agbada formation, ranked among the world’s major hydrocarbon provinces. The traps, structure and stratigraphic, could be very subtle and complex and are therefore, difficult to map accurately. The degree of reliability and precision of the mapping can be greatly enhanced by integrating seismic data with well logs commonly used independently in hydrocarbon exploration and exploitation studies. In this paper, seismic data were integrated with well logs to define the subsurface geometry, stratigraphy and hydrocarbon trapping potential of Emi-field, off shore Niger Delta. Lithologic units were identified on the logs and correlated across the wells. The stratigraphic cross-sections produced show a general lateral continuity of the lithologic units across the field. Seismic-to-well ties revealed that, high amplitude reflection events correspond to sand units, whereas, low amplitude reflection events correspond to shale units. Four horizons, H1, H2, H3and H4 were mapped and structure contour maps produced for each of the horizons. Closures considered as good hydrocarbon prospects were identified and delineated. Stratigraphic plays such as pinch-outs, unconformities, sand lenses and channels are also suspected. The integration of seismic data with well logs proved to be a useful tool in structural and stratigraphic mapping and in predicting lateral and vertical variations in the lithologic units. Key words: Seismic, structural interpretation, well logs, Niger Delta, stratigraphic mapping, integration.