Onshore FWI in India: S-Cube & ONGC Recognised at SEG Bengaluru for Bengal Basin Results

At the SEG Transforming Energy Exploration: Technology, Sustainability, and Innovation Symposium in Bengaluru, S-Cube and ONGC (GEOPIC) presented full waveform inversion (FWI) results from onshore India: a legacy dynamite survey in the Bengal Basin, inverted with Time-Space-Lag FWI (TSL-FWI™) to update velocity below 6 km. Alongside it, the team showed the offshore Mahanadi Basin results that preceded the land project.

These are the first FWI results shown on real Indian field data, onshore and offshore, and they are being used to guide ONGC's exploration and development decisions in both basins.

Speakers recognised by SEG

Vikas Vats (S-Cube), Christos Mavropoulos (S-Cube) and Saheb Ghosh (ONGC-GEOPIC) each received an SEG Certificate of Appreciation for their talks and for their work bringing FWI to Indian land data. Saheb Ghosh presented the Bengal Basin case study, Christos Mavropoulos covered how TSL-FWI™ changes onshore velocity model building, and Vikas Vats showed how FWI holds up away from well control.

Nikhil Shah (S-Cube) was also recognised by SEG for his keynote, Next Generation FWI for Land and Marine Applications, which presented the Mahanadi Basin results shown below.

Onshore Bengal Basin: deep velocity from a legacy dynamite survey

The Bengal Basin data is an older onshore dynamite survey with a thick carbonate layer that distorts imaging of everything beneath it. Land data adds its own problems: near-surface heterogeneity, static shifts, ground roll and limited offsets. Conventional trace-by-trace FWI tends to cycle skip on data like this, when synthetic and recorded waveforms are more than half a cycle apart and the inversion converges to the wrong model.

TSL-FWI™ matches waveforms adaptively across time and space lags instead of sample by sample, so it can start from an inaccurate initial model and still update the deep macro-velocity without long offsets or very low frequencies. On the Bengal Basin survey it:

• corrected deep structural distortions at depths below 6 km;
• updated velocity 4x deeper than the diving-wave penetration limit;
• estimated velocity and reflectivity together from the same inversion;
• did this on existing data, with no re-acquisition.

Offshore Mahanadi Basin: where the collaboration started

The land project followed S-Cube and ONGC's 2025 work in the deepwater Mahanadi Basin, where the existing streamer velocity model lacked the detail to image key targets. TSL-FWI™ resolved gas-charged Mio-Pliocene channel-levee complexes from scratch, giving a velocity framework for reservoir characterisation.

ONGC's deepwater drilling campaign on this play began in July 2026. In September, ONGC reported gas from the first well, MN-DW18-1-H-D off Odisha, with encouraging flow and reservoir pressure.

What this means for exploration in India

• Legacy land surveys can be re-used: deep velocity updates from older onshore dynamite data extend target depths without new acquisition.
• One method onshore and offshore: the same TSL-FWI™ workflow produced results on Bengal Basin land data and Mahanadi Basin streamer data.

Learn more in our Mahanadi Basin case study and the symposium programme.