Statistical seismicity analysis methods for the detection of fault activation during fluid injection


Fluid injection operations and the connected increase in pore pressure can have undesirable side effects such as induced seismic activity, fault slip and wellbore damage. Here, we present two statistical methods that allow for an identification of fault activation and induced seismic activity. First, we differentiate induced from tectonic seismicity based on a significant increase in background seismicity rates. We determine temporal variations in background rates by fitting earthquake interevent-times with a two-parametric gamma distribution. The corresponding parameters provide insight into short-period aftershock clustering and longer period background seismicity rate changes. We show that temporal changes in background rates can be used to identify regions with induced seismicity in the central United. Second, we identify fault activation processes by analyzing temporal variations in Gutenberg-Richter b-value A significant drop in b-value can potentially be indicative of fault activation during continuous injection operations. Adjusting injection operations in response to jumps in background rates and decreasing b-values may help control fault activation and induced earthquake activity.

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SEG Technical Program Expanded Abstracts