Post-stack denoising of legacy reflection seismic data: implications for coalbed methane exploration, Kalahari Karoo Basin, Botswana.

We have recovered legacy 2D seismic data from the Kalahari Karoo Basin, Botswana, which show signatures associated with the coalbed-methane-bearing seams of the Mmamabula and Morupule formations. These deeply buried coal seams (∼ 500 m below surface) may represent a new alternative source of energy for the region. Prior to interpreting the seismic data, we improved imaging of the coal seams by attenuating noise with the curvelet transform. The data were transformed to the curvelet domain, and scale and angular direction thresholds were selected and applied, thereby removing previous processing artefacts and noise. The resulting denoised seismic data are characterised by a high signal-to-noise ratio, showing a clear continuity of the seismic reflections associated with the coal seams. We constrained the seismic interpretation with borehole logs, which confirmed the locations of the coal sequence at the top of the Mmamabula and Morupule formations. The curvelet-denoised seismic sections enable a more reliable mapping of the coal zone, which is displaced by major faults with throws of up to ∼ 500 m. Following these encouraging results, we emphasised the value of enhancing and reinterpreting legacy data, as it is a cost-effective and environmentally-friendly method for deep coal seam and mineral exploration. [ABSTRACT FROM AUTHOR]