Journal de géologie et géophysique
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Indications of Hydrocarbon Prospects in the Lower Benue Trough from Aeromagnetic Data

Choko Chukwuemeka*, Chukwuemeka Ngozi Ehirim, Joseph Onukansi Ebeniro

The hydrocarbon prospect of the lower Benue trough has been investigated using aeromagnetic data. Objectively, the study was meant to evaluate structure, lithology and sedimentary thickness that could have direct bearing to hydrocarbon formation and due to the proximity of the study area to the hydrocarbon-rich Niger delta to the south and the discovery of hydrocarbon in Kolmani River II well in Gongola basin, Chad and Niger republics to the northeast that share similar geologic settings. Maps of magnetic parameters were generated using Oasis montaj, Surfer 13 and Arc GIS softwares for subsequent qualitative and quantitative interpretations. Results of the study reveal low and high magnetic anomalies that correspond to basement valleys with thick sedimentary cover and uplifted basement areas with thin sedimentary cover, respectively. Low lineament density, Low magnetic anomalies were delineated in Akwa, Agwu, okposi and Nkalagu areas with 3318.9 m sedimentary thickness which is adequate for the thermal maturation of potential source rocks and hydrocarbon formation. A dominant NNE-SSW structural trend believed to be the continental extension of oceanic fracture system was mapped. This controls sediment deposition, hydrocarbon migration and trap mechanisms that could have direct bearings to the formation of hydrocarbon plays in the trough. Geologic map correlated with the residual magnetic map reveal that areas of low magnetic anomalies with thick sediments corresponds to parts of the Mamu and Nkporo shale formations and Ajali sandstones which are known petroleum systems in the lower trough. With appropriate and favorable juxtaposition of these geologic elements and tectonic structures, prospective hydrocarbon systems could have been formed for possible exploitation in the lower Benue trough. Akwa, Agwu, okposi and Nkalagu areas were thus recommended for detailed seismic surveys.