Fluid-induced Seismicity: Pressure Diffusion and Hydraulic Fracturing

It has been already recognized that the passive seismic monitoring has a significant potential to characterize physical processes related to fluid dynamics in hydrocarbon reservoirs. One of its conventional applications is mapping of hydraulic fracturing. However, this is not the only application. Understanding of the spatio-temporal dynamics of microseismic clouds can significantly contribute to estimating important physical characteristics of fracturing processes and of reservoir properties. For instance, r-t-analysis turns out to be very useful. E.g., plots of distances from the injection source to event hypocenters versus event occurrence times show signatures of the hydraulic fracture opening, fracturing fluid loss and its infiltration into reservoir rocks as well as the diffusion of fluid pressure into surrounding formations. The back front of the induced seismicity is especially useful for characterization of fractured domains after terminating the injection.