Subsurface Imaging

While Land Full-Waveform Inversion (FWI) has been applied to seismic data in Oman, its use has typically been limited to low-frequency updates for migration. This technical article presents a breakthrough application of acoustic FWI up to 35 Hz, enabled by optimized data conditioning, initial model preparation, and velocity inversion. The resulting FWI Image, derived from the velocity model, delivers a superior view of the complex fault system, surpassing conventional imaging methods by leveraging the full wavefield and least-squares fitting across all frequencies.

Accurate near-surface imaging in the Middle East is challenging due to strong velocity contrasts in the shallow geology. This technical article highlights the application of Elastic Full-Waveform Inversion (FWI) of surface waves, leveraging low-frequency virtual data from 3D interferometry and active surface waves to build a detailed shear velocity (Vs) model. Compared to legacy models, the updated Vs model delivers improved subsurface resolution, simplified geological structures, and better alignment with well markers, enhancing overall seismic imaging.

Getting the full vaue of reflected waves is crucial for successful Full-Waveform Inversion (FWI), especially in seismic data with short offset coverage. This article introduces Dynamic Resolution Time-Lag FWI (DR-TLFWI), a method designed to strengthen the tomographic term in the FWI gradient by applying dynamic weighting based on illumination volume during each iteration. By using a time-lag cost function, the approach mitigates cycle-skipping and balances low- and high-wave number velocity updates, improving subsurface imaging beyond the reach of diving waves. Field data results show enhanced velocity models, clearer structural delineation, and better reservoir interpretation.