Study of Curie point depth and heat flow from spectral analysis of aeromagnetic data for geothermal potential of Gubio, Chad Basin, Nigeria

Abstract

Aeromagnetic data of Gubio area, Chad Basin, northeastern Nigeria, were interpreted quantitatively by employing spectral analysis technique with the aim to estimate the Curie point depth, geothermal gradient and heat flow in order to determine the geothermal nature of the area. Data enhancement (reduction to pole, RTP and band pass filter) was performed on the total magnetic intensity (TMI) map of the area using oasis Montaj software. The enhanced map was divided into four overlapping blocks, and each block was subjected to spectral analysis. The results gave Curie point depth values ranging from 10.63 to 20.07 km, with deepest depth at the northeast, while the shallowest depth was observed to be conspicuous in the southeastern part of the study area. The estimated geothermal gradient ranges from 28.90 to 54.57 °C km−1 with an average value of 40.26 °C km−1, with low values in the northeast direction, and increases towards southeast. The average geothermal gradient of 40.26 °C km−1 indicates the possibility of hydrocarbon generation and accumulation in Chad basin. The estimated heat flow values range from 72.24 to 136.43 mW m−2 with an average value of 100.65 mW m−2, the highest values are found around southeastern part of the study area, and the lowest values are within the northeastern part. The areas of geothermal anomalies with gradient above 50 °C km−1 may be good areas for geothermal reservoir exploration for an alternative source for power generation.