Microseismic Monitoring of Hydraulic Fracturing - Physical Fundamentals of Interpretation

Several basic dynamic processes related to propagation of hydraulic fracturing modify the effective stress in rocks and, therefore, they are relevant for triggering of microseismicity. For instance, these are the creation of the new fracture volume, fracturing fluid loss and its infiltration into reservoir rocks as well as diffusion of the injection pressure into the pore space of surrounding rocks and inside the fracture. Here, using real data we show these processes can be seen from features of the spatio-temporal distributions of the induced microseismicity. Especially, the initial stage of the fracture volume opening as well as the back front of the induced seismicity starting to propagate after termination of the fluid injection can be well identified and used for reservoir engineering.