Make the Most of High Frequency Seismic Data in Onshore Reservoir Characterization: A Case Study from Uganda.

The study area is located onshore North West of Uganda. Legacy data already exists but a new acquisition with a dedicated processing has been performed in order to improve resolution at target. However, several challenges need to be overcome: a considerable amount of refraction noise pollutes the recorded data which shows a significant stretch at far offsets, unusual predominance of high frequency energy and a considerable variability in terms of spectral content between the different angle-stacks. The highly unconsolidated sediments setting yields to poor quality sonic logs. A successful reservoir characterization is achieved by devising a workflow which takes into account the peculiar spectral content of the seismic angle-stacks and optimizes the coherency between them while preserving the high frequency information. This way, the resolution of the inverted results with respect to legacy inversion study is improved with an impact on development wells positioning and completion strategy. Through an ad-hoc preconditioning we show how the limited bandwidth overlap between different angle-stacks is not a major obstacle for the success of the inversion. Comparison with CI shows that an elastic inversion provides extra added value in terms of reservoir characterization compared to a simpler method working separately on different angle-stacks.