Geophysics Department Seminar: Leo Eisner (Academy of Sciences of the Czech Republic) - Induced seismicity and hydraulic fracturing
Title: Induced seismicity and hydraulic fracturing
Abstract: Hydraulic fracturing induces seismic events, sometimes even felt at surface. Despite long history of various scientific investigations there is lack of understanding of how the hydraulic fracturing induces the seismicity in general and specifically microseismicity, i.e. small events with Mw<0. We agree that only small fraction of injected energy is radiated as seismic energy unless some unusual circumstances happen.
In the first part of my talk I will discuss a new insight into the induced microseismicity from monitoring of hydraulic fracturing in shale sedimentary formations focusing. There are numerous proposed models of interactions between microseismicity and hydraulic fracture and I will show that none of the previously considered models fits observations. This will allow me to propose an alternative explanation of the induced microseismicity.
In the second part of my talk I will try to touch on the unusual circumstances where hydraulic fracturing, and generally fluid injection induce felt events. I will show a new geomechanical model allowing us to relate injection rates fluctuations and seismicity rates. This model then enables simple differentiation between induced and natural seismicity.