Abstract

The high resolution aeromagnetic data over part of middle Benue trough was interpreted quantitatively using Spectral depth analysis and Source Parameter Imaging (SPI) of the magnetic source rocks to determine the sedimentary thickness for hydrocarbon maturation and accumulation. The study area is bounded with longitudes 09°00′ - 10°00E and Latitudes 08°30′ - 09°30′N with an estimated total area of 12,100 km². The regional/residual separation was carried out using polynomial fitting with order one. The pre-process grids dx, dy and dz from residual grid was used as an input grid to calculate the source parameter imaging. The same residual map was subdivided into nine blocks for spectral analysis. The result from source parameter imaging reveals maximum sedimentary thickness of 2.21 km at the extreme southern part of the study area which corresponds to part of Kwolla and Shendam. Minimum depth of 0.05 km is obtained at the northwestern part of the study area which corresponds to Pankshin. The result from spectral analysis also shows similar maximum depth of 2.54 km in the same area as SPI and minimum depth of 0.51 km area as SPI and minimum depth of 0.51 km. Since the sedimentary thickness of 3.0 km and above is only sufficient for hydrocarbon maturation and accumulation, then the result from this present study might not be sufficient enough for hydrocarbon maturation and accumulation but might be good for hydrocarbon gas accumulation.

Key words: Aeromagnetic data, hydrocarbon, maturation, polynomial fitting, spectral analysis.