Looking at All the Energy - Taking Passive Seismic Beyond Microearthquakes

This work will briefly describe a new seismic imaging method that provides comprehensive assessments of passive seismic activity well beyond traditional microearthquake studies. The method sums cumulative seismic activity over time. We describe the method then illustrate applications with case studies. Data is collected from surface or buried arrays. Products include standard deliverables such as hypocenters and focal mechanism solutions, and new products such as movies of cumulative activity in 3D and direct images of hydraulic fractures and natural fracture systems as complex surfaces and networks. The results reveal hydraulic fracture processes in unprecedented detail. Also, potentially transmissive fractures can be imaged with only ambient seismic emissions, i.e. with no added energy from hydraulic fractures, to identify fracture sweet spots prior to drilling. The method is vastly more sensitive than standard microearthquake (MEQ) methods for two reasons: 1. Computations use the total trace energy rather than only distinct events with pickable first arrivals. 2. The energy is summed over time periods ranging from fractions of a second for MEQ detection to minutes, tens of minutes, hours or even days. Longer summations provide direct imaging of hydraulic fractures and fracture networks and images volumetric activity through time.