Assessing the Processing and Imaging Challenges of DAS VSP Data for CO2 Storage Imaging and Monitoring
We discuss challenges of Distributed Acoustic Sensing (DAS) data in a Vertical Seismic Profile (VSP) setting and propose processing and imaging solutions to overcome these. The context is to review processing challenges and benefits of DAS VSP as a potential cost-effective solution for CO2 storage monitoring. DAS VSP data acquired during a monitor surface seismic acquisition over the Johan Sverdrup field in 2021 provides the means to assess this, with both learnings and uncertainties from this study informing on the potential of this technology in other geological settings. Here, an initial feasibility assessment conducted using a baseline and repeat monitor survey, acquired a few weeks later, indicated the achievable levels of repeatability with this data type. An inclusive pre-processing flow and use of both up-going and down-going wavefields in a tailored imaging routine showcases the level of subsurface illumination and high signal-to-noise levels for 3D reservoir imaging. Finally, subsequent CO2 modelling work provides an understanding of the potential of DAS VSP surveys for future 4D monitoring work for conventional or un-conventional reservoir monitoring