Diagnosing Azimuthal Variations of Velocity Model Uncertainties using 3D DAS-VSP in GOM

Li, Y. (Shell International E&P) | King, K. (Shell E&P) | Wong, W. (Shell International E&P) | Chen, T. (Shell International E&P) | Wu, H. (Shell E&P)



As Distributed Acoustic Sensing (DAS) systems advance, increasing amounts of 3D/4D DAS-VSP (vertical seismic profile) data are being acquired. These large amounts of DAS data are used to diagnose and update velocity models and improve the quality of sub-surface images from both borehole and surface seismic data. In this study, we developed a simple, robust, and practical tool to diagnose azimuthal variations of velocity model uncertainties using 3D DAS-VSP data. We use 2211 seismic shots on 8 rings centered at a receiver to calculate apparent velocities (Vapp) using an initial model (Mod) and an updated model after tomography (Tom). Relative misfits between observed and model calculated Vapp reveal azimuthal variation in velocity model uncertainties.