SUMMARYIn 2012, Shell acquired its first dual-well 3D DAS-VSP (Distributed Acoustic Sensing -Vertical Seismic Profiling) data concurrently with an OBS survey in a deep water environment in the Gulf of Mexico. A work flow was developed to process the 3D DAS-VSP data and use the VSP first arrival times to diagnose the velocity models which were derived from previous surface seismic surveys for selecting a suitable initial velocity model to be updated with the travel time tomography inversion. The VSP diagnosis method was applied again to the updated VTI-inversion model to ensure the velocity updating effort is in the right track. Both DAS-VSP and OBS data were migrated with the initial VTI velocity model and the updated VTI-inversion model. It is found that both borehole and surface seismic images generated with the VTIinversion model are significantly improved from those obtained with the initial model, especially for the seismic amplitudes at the target event. In this paper, we will share our processing procedure and some learning from our practices of processing marine 3D DAS-VSP data. Processing results from borehole seismic data acquired in Well 1 will be presented as examples.

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