Bandwith Coupling Issues in Recording Passive Seismicity

Passive seismic recording systems are typically designed to monitor microseismicity (M < 0) and as such are frequency band-limited. For effective monitoring full field monitoring, a broadband recording approach needs to be considered in order to expand the magnitude range from -4 < M < +4. Based on data recorded using standard downhole approaches for both hydraulic fracture and long term reservoir monitoring we (1) outline frequency and bandwidth limitations, (2) examine resonance effects on interpretation, (3) evaluate coupling effects associated with temporary deployments, and (4) assess how these issues affect the interpretation. We (5) also analyze the role of magnitude saturation and define the need for a hybrid recording approach, utilizing both low frequency sensors situated near or at surface with downhole high frequency phones, in order to avoid some common pitfalls in recording passive seismicity.