Omori Law for Fluid Induced Microseismicity and Its Dependency on Parameters of Reservoir and Source

摘要

In this paper we present striking similarities between the temporal occurrence of aftershocks after earthquakes and the temporal distribution of microseismic events induced during the post stimulation phase of fluid injections. We assume that microseismic events induced through fluid injections are triggered by a pure diffusive process of pore pressure relaxation. We improve an existing formulation for the seismicity rate of fluid induced microseismicity, which is developed based on this assumption. In this way we derive to a formulation, which describes the temporal distribution of microseismic activity in dependency on the parameters of source and reservoir. We show that the well known Omori law, which describes the frequency of aftershock occurrence, can be transferred to the case of fluid induced microseismicity to explain the temporal distribution of events induced after injection stop. Even in seismology the controlling parameters of the p-value of the Omori law are still under discussion. Here we identify the controlling parameters of the p-value for fluid induced seismicity and show, which of the parameters of source and reservoir can be reconstructed by a p-value analysis. Finally, we apply the developed theory to synthetic data sets and to the Fenton Hill real data example.