Seismic Reflection Profiling for Coal Bed Mapping in the Anambra Basin

This study applies seismic reflection profiling to map the geometry and continuity of coal beds in the Anambra Basin, South East Nigeria. Nigeria's coal resources in the Anambra and Benue Basins represent strategically important energy reserves, but their development has been constrained by inadequate subsurface characterisation. Seismic reflection profiling provides the spatial resolution needed to map coal seam geometry, depth, and lateral continuity required for mine planning and resource estimation. This study acquires a 12-kilometre 2D seismic reflection line across a coal mining concession area in Ankpa, Kogi State, at the boundary of the Anambra Basin using a 96-channel land seismic acquisition system with geophones at 5-metre intervals. A downhole seismic source is used to generate bandwidths suited to imaging targets at 100 to 600 metres depth. Processing includes geometry assignment, filtering, deconvolution, velocity analysis, NMO correction, stack, and post-stack migration. Results are calibrated to the available stratigraphic log from the Ankpa Mine No. 2 exploration borehole. Findings reveal three distinct coal seam reflections at 180 to 490 metres depth within the Mamu Formation sequence. The main coal seam shows consistent thickness of 1.5 to 3.2 metres and dips 8 degrees to the southeast at the base of the profile. Two minor coal seams show lateral discontinuities interpreted as erosional channel incisions. A structural inversion feature creates a gentle anticlinal fold that results in shallowing of the main seam to 155 metres at the crest. The study provides the first seismically-constrained coal geometry model for the Ankpa area.

Keywords: seismic reflection, coal bed mapping, Anambra Basin, Mamu Formation, mine planning.