Unconventionals in Seismic Monitoring

Passive seismic monitoring gives essential information on reservoir dynamics, cap-rock integrity, propagation and extend of fracking activities, and eventual hazard scenarios by potential triggering of induced seismicity. Data analysis can either be performed by classical, seismological tools for determination of single-event properties like hypocenter, origin time, magnitude, and moment tensor to characterize the stress field and the related source mechanisms of relevant micro-earthquakes. Or one exploits innovative approaches to derive in-situ stress changes by statistical properties of large populations of small events (Grob and Baan, 2011). Both approaches apply equally well to standard and unconventional reservoirs; however, the more rapid changes in the latter make all kinds of time-lapse 4D monitoring even more attractive (Forgues et al., 2011).