Gemini-Enabled Sub-Hertz Elastic FWI for Subsalt Velocity Model Building

This technical report evaluates the impact of Gemini-enabled sub-Hertz acquisition on subsalt velocity model building using Elastic Dynamic Matching Full-Waveform Inversion (E-DMFWI). It outlines how the convergence of advanced acquisition techniques and robust inversion methods enhances model tolerance, facilitates salt reconstruction from sediment-flood models, and stabilizes subsalt velocity updates. The study presents field examples demonstrating that starting FWI at 0.6 Hz significantly improves background velocity recovery and subsalt imaging coherence compared to traditional workflows initiated at 1.6 Hz. The report details the challenges of conventional full-waveform inversion, particularly its sensitivity to initial model inaccuracies and cycle skipping in complex geological settings. It further discusses the feasibility of direct salt reconstruction from sediment models using ultra-low frequency data, highlighting the advantages of E-DMFWI in enhancing the accuracy and reliability of subsalt imaging. The findings indicate that sub-Hertz data provides sufficient sensitivity for effective velocity model updates in challenging subsurface environments.