Update on DAS and geophone VSP surveys at the CaMI Field Research Station, Newell County, Alberta
Donald C. Lawton, Adriana Gordon, Svetlana Bidikhova, Kevin W. Hall, Malcolm B. Bertram
As part of on-going seismic monitoring at the CaMI Field Research Station (CaMI.FRS), vertical seismic profiles are being recorded unto a 24-level permanent downhole 3-component geophone array as well as helical wound and straight optical fibre for Distributed Acoustic Sensing (DAS). Advances over previous processing included smoothing DAS first break picks, application of both a median and FK filter to separate and enhance the upgoing energy, and careful assessment of shot statics based on minimizing the error between observed and computed first break travel-times. The velocity model for the VSP CDP transform for offset shots was determined initially from well-log data and the zero-offset DAS data, and then updated through matching computed and observed moveout for offset sources. Having the very near-surface velocities available from DAS data enabled a very robust 1-D velocity model to be established. This also improved VSP-CDP stacks of the borehole geophone data and the two datasets match closely. The final VSP-CDP stack enabled excellent imaging up to nearly 100 m from the VSP well for the DAS data and 64 m for the geophone data. After deconvolution, the processed geophone and DAS data correlated very well.