Long-term seismic monitoring of reservoir dynamics at Decatur

Accurate estimation of the moment magnitude of microseismic event catalogs is essential for proper estimation of moment release as well as for the extraction of source parameters that can reveal variations in the reservoir geomechanics and hydraulic properties. Using Decatur as an example we present how an improper choice of the analysis bandwidth and lack of instrument correction can lead to an underestimation of larger magnitudes which may affect the functionality of traffic light protocols. Spatial variations of Gutenberg's b-value within selected seismicity clusters at Decatur are associated with seismicity migrating over time along the cluster orientations, suggesting differences in either the medium or fault properties and changes in pore pressure. The different b-value regions are supported by clear systematic difference in frequency-magnitude distributions.