A case study of aeromagnetic data interpretation of Nsukka area, Enugu State, Nigeria, for hydrocarbon exploration

Abstract

The aeromagnetic data of Nsukka area was interpreted qualitatively and quantitatively. Standard Euler deconvolution, Source Parameter Imaging (SPI), Forward and Inverse modeling techniques were employed in quantitative interpretation with the aim of determining depth/thickness of the sedimentary Basin, magnetic susceptibilities and type of mineralization prevalent in the area. Oasis montaj 6.4.2 software and potent Q 4.10.07 software were employed in the data analysis. Forward and inverse modeling estimated depths for profiles 1, 2, 3, 4 and 5 were 1644, 2285, 1972, 2193 and 1200 m respectively, with respective susceptibility values of 0.0031, 0.0073, 1.4493, 0.0069 and 0.0016 which indicate dominance of iron rich minerals like limonite, hematite, pyrrhotite and pyrite, and forms lateritic caps on sandstones. Results from SPI estimated depth ranges from 151.6 m (outcropping and shallow magnetic bodies) to 3082.7 m (deep lying magnetic bodies). Depths of shallow magnetic sources resulting from lateritic bodies in the outcrops within the study area as estimated by Euler depths for the four different structural index (SI = 0.5, 1, 2, 3) ranges from 7.99 to 128.93 m. 35 to 150 m depth are good potential water reservoirs for Nsukka and environs. Depths of 1644 to 3082.7 m show sufficiently thick sediments suitable for hydrocarbon accumulation.

Magnetic Basement Depth and Structure over Parts of Bida Basin, Nigeria Interpreted from 2-D Spectral Analysis and 3-D Euler Deconvolution

“…The deeper sources ranged from 2.81 to 3.24 km while the shallow sources ranged from 0.45 to 1.49 km with an average depth of 2.90 km. A spectral analysis of the northern Bida Basin as done by Nwankwo et al (2008) revealed a depth range of 0.24 to 1.74 km for the shallow magnetic sources while magnetic basement depths values of 0.52 to 4.38 km were encountered close to the central parts of the basin.Structural analysis using aeromagnetic data was effectively demonstrated by similar works done by Daniel et al (2015), Ugwu et al (2013), Igwesi and Umego (2013), and Adetona and Abu (2013)within the lower Benue Trough around Nsukka, Okigwe, and Afikpo areas. Whereas in the Chad Basin, Anakwuba et al (2011) and Chinwuko et al (2012) carried out an in-depth structural analysis of its southern axis through the interpretation of aeromagnetic anomalies.…”

Investigation of Gully Erosion Using Integrated Electrical Resistivity Methods in Parts of Enugu North Zone, Southeastern Nigeria

“…Figure 1 The geology of Enugu North is situated in the Anambra Basin (Figure 2). The geologyof the succession of strata in the Anambra basin has been described by different authors (Obiora et al, 2015;Ekwueme et al, 2017;Nwajide, 2013;Obaje, 2009;Adetona and Abu, 2013;Odumoso et al, 2013;Adeigbe and Salufu, 2009). There are six basic rock classification in Anambra Basin including; Enugu shale, Mamu formation, Agwu shale, Ajali formation, Nsukka formation and Imo shale formation.…”

Environmental assessment of gully erosion in parts of Enugu north, Southeastern Nigeria

“…Sediments deposited within this time interval occur in four distinct physiographic provinces, namely the Cross River plains, the Escarpment, the Plateau and the Anambra Plains. Some of these sediments are of considerable economic importance and contain reserves of coal, natural gas, glass sands and considerable prospects for liquid hydrocarbon according to (26) . The topography is aptly defined by the Nsukka-Okigwe cuesta which stretches from Eha Alumona to Obollo Afor as its higher limit and Eha-Amufu as the lower limit.…”