Statistical Analysis of Microseismic Noise during Hydraulic Fracturing

Spatial and temporal spectral analysis of the background noise before and during hydraulic fracturing shows that surface noise is generally uncorrelated before and after well injections. Noise becomes sufficiently coherent (correlated) during fluid injection and even during a break between fracturing stages. Stacking of seismic array records with proper move-out corrections of Seismic Emission Tomography (SET) helps to suppress non-correlated noise component, but enhances both correlated technogenic noise and signals from microseismic events. Presence of correlated noise can be a factor increasing number of false alarms in microseismic bulletins which are created by semblance-based SET techniques.