Interpretation of high-resolution aeromagnetic data within Dahomey basin, Nigeria; case for hydrocarbon prospectivity

Abstract

High resolution digital aeromagnetic data acquired by the Nigerian Geologic Survey Agency, over a part of the Dahomey Basin, Nigeria, were analyzed; to investigate the hydrocarbon prospectivity of the basin using magnetic hydrocarbon indicators. The Derivatives, Source Parameter Imaging (SPI) and Magnetic Forward modeling techniques were employed with the aim of determining geometry and depth/thickness of the sedimentary Basin. Intra-sedimentary magnetic anomalies with possible association with hydrocarbon
occurrence were enhanced by the application of band pass filters. The derivative maps revealed parallel to subparallel trending NE-SW, NW-SE and E-W lineaments probably caused by fracture zones in the basement, some of which propagate as faults into the overlying sedimentary formations. The thickness of the sediments in the study area varies from 1.5 km in the north-eastern region, 6.5 km in the south-eastern region to 7.8 km in the east-central region. The results revealed that the eastern part has a higher hydrocarbon prospectivity which correlate with the well logs based on the magnetic indicators. The Butterworth band-pass filtered map displayed
some magnetic aureoles, often associated with hydrocarbon seepages. These aureoles characterize the deepest parts of the basin in the east-central and south-eastern parts, which is an indication of the existing exploratory wells that are mostly dry. It was concluded that the east-central and south-eastern parts of the basin investigated show a combination of favorably thick sedimentary formation, faults, fractures and magnetic aureoles probably represented areas of better potential for hydrocarbon exploration and were thus recommended for detailed seismic surveys.