Reconnaissance Hydrocarbon Prospecting of Afikpo, Oban Massif and Up-Dip Niger Delta, Nigeria

The purpose of this study is to identify areas with requisite sedimentary thickness and geothermal gradient capable of supporting the formation and accumulation of hydrocarbon fluids from organic rich source rocks. It also aims to delineate intra-sedimentary features that promote hydrocarbon migration and compartmentalization within reservoir rocks in Afikpo, Oban Massif and Niger Delta basins, southeastern Nigeria. Depths to the top and base of the magnetized crust were determined using statistical-spectral analysis of the aeromagnetic data contained in several square windows. The centroid method was applied and the results verified using forwarding modeling of the spectral peak. The results of spectral analysis show that the sedimentary thickness within the study area ranges from 1.35 to 3.84 km. Curie point depths (CPDs) obtained varies between 12.99 and 34.92 km. The maximum and minimum geothermal gradient values are 43.99° and 15.75°Ckm−1, respectively. These values show reasonable agreement with the results of earlier studies carried out in the region and nearby analogue basins. Some of the areas with shallow CPDs coincide with locations of thin sedimentary thickness, and deeper CPD regions correlate with areas of thick sedimentary cover. Good consistency was observed between the CPDs and geothermal gradient as areas of shallow CPDs tallied with zones of moderate and high temperature gradients. These results of geothermal gradients show remarkable agreement with wells data acquired within the Niger Delta Basin. The north–central, north–western and southeastern regions, which show sedimentary thickness of over 3 km in the presence of active intra-sedimentary structural elements as well as favorable temperature gradients, are recommended for further detailed petroleum system analysis.