EVALUATION OF SUBSURFACE STRUCTURES USING HIGH RESOLUTION AEROMAGNETIC DATASET FOR HYDROCARBON POTENTIAL PROSPECTIVITY IN PARTS OF THE ANAMBRA AND SOUTHERN BIDA BASINS, NIGERIA

Abstract

This study focuses on the evaluation of subsurface structures using high resolution aeromagnetic dataset for hydrocarbon potential prospectivity in parts of the Anambra and Southern Bida Basins, Nigeria. Four high-resolution aeromagnetic data were collected, analyzed and evaluated to interpret the structural framework, assess basement topography, and evaluate the hydrocarbon potential of the study region. The datasets were interpreted using a combination of geophysical interpretation tools such as Oasis Montaj, Surfer, and Geo Rose software. Results from qualitative analysis of the residual anomaly map (RAM), the reduce to pole (RTP) map and the rose diagram reveals significant northeast to southwest (NE-SW) trending faults within the region, reflecting the regional tectonic regime. This conforms to the trend of the Benue Trough. The result also reveals evidence of other structural feature such as folds in the area. These faults form potential migration pathways and trapping mechanisms for hydrocarbon accumulation. Lineament analysis as reveal by the Analytical signal map showed dense fault networks predominately around the southern area, with prominent basement depressions that could serve as accommodation spaces for sediments. The identified structural traps, coupled with the thick sedimentary cover and fault-controlled migration pathways, suggest that the study area is prospective for hydrocarbon accumulation. The sedimentary thickness obtained through Spectral analysis ranges from 0.42 km – 5.24 km with average of 1.72 km across the study area. The deep sedimentary cover signifying deep depth to magnetic sources vary from 2.03km to 5.24 km, whereas the shallow sedimentary cover (shallow depth to magnetic sources) varies from 0.41 km to 1.85 km. The sedimentary cover map reveals deeper sedimentary cover in the southern and central parts of the study area while, the shallower sedimentary cover occurs in the northern parts. The result of the estimated oil and gas window is between 74.78 °C and 150.21 °C across the study area. The study concludes that there is likelihood of hydrocarbon generation in the southern and central regions of the study area, whereas, the northern and other parts of the study area appear plausible for mineral exploration.