Resolving complex velocity and gas absorption features with fullwaveform inversion in the Taranaki Basin, New Zealand

Summary

The Western Platform multiclient survey is in the Taranaki Basin, offshore New Zealand. Legacy imaging efforts have suffered due to being unable to overcome the presence of multiple geological challenges. A complex shallow overburden across the survey area, in addition to The Cape Egmont Fault Zone, provide a significant challenge to velocity model building. Shallow gas clouds are also prevalent throughout the survey, impacting imaging at the key zones of interest.

To address these challenges, full-waveform and common image point tomography were performed to derive a high-resolution velocity model. Q-FWI was used to derive a detailed Q model representing the shallow gas bodies.

In this case study, we demonstrate the successful application of diving-wave FWI, Q-FWI, and FWI using reflection energy to resolve a high-resolution velocity and Q model. This detailed model enabled the final imaging performed with Q-Kirchhoff prestack depth migration to compensate for the complex kinematics and gas-related absorption effects observed in the survey.

• velocity model building
• Q-full-waveform inversion
• least-square reflections full waveform inversion
• gas cloud imaging