Automated CO2 Detection by Focused Seismic Monitoring using Optical Fiber DAS-VSP Data

VSP data recorded with an optical fiber and a DAS system can be fruitfully used for focused seismic monitoring in a structural deconvolution approach. The DAS data can be under sampled in depth. A conventional VSP processing sequence is applied to a set of DAS-VSP recorded for monitoring of CO2 injection. The corridor VSP stacked traces are compared to synthetic seismogram. A deconvolution process is used to fit corridor stacked traces and synthetic seismograms. The efficiency of the process is evaluated by measurement of correlation and NRMS coefficients. The monitoring procedure has been completely automated both in the processing of the data but also in the detection of CO2 based on seismic attributes: computation of a residual time shift curve associated with differential instantaneous amplitude criteria.