Oil & Gas | Viridien

Maximizing the Contribution of Reflections by Dynamic Resolution Time-Lag Full-Waveform Inversion

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.

Joint seismic VVAz-AVAz inversion: case study Offshore Abu Dhabi

Fracture characterization is critical for optimizing reservoir production. Velocity Variation with Azimuth (VVAz) and Amplitude Variation with Azimuth (AVAz) are the primary methods used in the industry for characterizing azimuthal anisotropy, whether fracture- or stress-induced, from PP seismic data. While each method has its strengths and limitations, they are often used separately to predict fracture networks in reservoirs. This paper presents a joint azimuthal velocity and amplitude inversion workflow for characterizing fracture orientation and intensity in a Middle East offshore carbonate reservoir, utilizing a high-density WAZ ocean-bottom cable (OBC) 3D seismic survey.

Elastic time-lag full-waveform inversion using OBN data in shallow water environments

Shallow water environments pose challenges for seismic inversion due to hard water-bottoms and near-surface complexities causing guided waves and elastic effects. Conventional acoustic-based full-waveform inversion (FWI) struggles in such conditions. This study demonstrates a time-lag FWI workflow using ocean-bottom node data from the North Sea. The approach models shallow heterogeneities accurately, producing clearer subsurface images. Elastic FWI further enhances deeper structures, particularly in complex chalk formations, offering superior event continuity and signal-to-noise ratios compared to traditional methods.