Imaging Complex Geology Offshore Angola Through Integration of One-sided WAZ Acquisition, Low Frequency Sources and Elastic DM FWI Model Building

Paper submitted to SEG Realizing the Energy Potential of Angola Symposium 2026, by Eric Frugier, Gan Yu, Jeff Tilton, Matheus Pila, Trong Tang, Matthew Plummer, Khaled Abdelaziz and John Brittan (TGS)

Summary

While parts of the Lower Congo Basin offshore Angola have mature plays, deeper sub-salt and pre-salt frontier opportunities remain underexplored, mainly due to imaging challenges caused by complex salt. This makes high-resolution imaging critical for prospect de-risking.

A recent Narrow Azimuth (NAZ) 3D multi-client survey across Blocks 33, 49, and 50 using one-sided wide-azimuth (WAZ) streamer configuration, low-frequency sources combined with an Elastic Dynamic Matching Full Waveform Inversion (E-DMFWI) workflow enabled robust velocity model building yielding improved subsalt imaging despite offset limitations. Using elastic modeling combined, we achieved a reasonable uplift in imaging quality in the post-salt and sub-salt by refining carbonate and salt geometries.

The integrated solution discussed in this paper provided an efficient solution for early-stage exploration in Angola’s salt provinces, paving the way for future discoveries and reinforcing Angola’s role as a key energy hub in West Africa.