Analysis of airborne potential field data for hydrocarbon exploration in Southern Nigeria

Abstract

The reservoir component of the petroleum system of the Niger – Delta has historically been accessed at depths ranging between 3.5 and 4.5 km, even though the Delta's sedimentary thickness is put at a maximum of 12 km as the basin has never been drilled to basement. The conventional assumption of the depth extent of reservoir facies within the Delta have been put to question as recent forays past the known limits yielded hydrocarbon production. Filtered, transformed, and enhanced airborne gravity and magnetic data acquired over the Niger Delta, southern Nigeria, were therefore analyzed to gain insight into the interval that has remained unexplored. A careful consideration of the zone suggests that the unexplored interval may accommodate interesting rock units and structures that could support the generation and preservation of hydrocarbon within some parts of the interval. Combined Spectral Depth Analysis (SDA) and 3D Euler Deconvolution employed to determine depth range to basement within the entire Niger Delta indicate that depth to basement rocks beneath the sedimentary unit ranges from 10–15 km, thus suggesting the presence of a Cretaceous sedimentary interval beneath the current drill depths that might be at least 6 km thick. Structural analyses of the basement rocks as well as the basement topography could reveal interesting structural pattern which when reactivated possibly engendered sedimentary structures within the sediments overlying them. Relevant information, such as generated from this study is expected to motivate interest to focus exploration target beyond the current drilling depth.