Induced earthquakes associated with the Haynesville shale play identified near Bienville Parish, Louisiana in 2011

English Abstract:

In the last decade, incidences of increased felt seismicity throughout the central United States have been correlated with wastewater disposal to support hydrofracturing operations. However, the relatively few incidences of induced seismicity compared to the number of operating injection wells over different regions is rather surprising. Thus, further investigation and positive identification of incidents of induced seismicity is needed. We focus an investigation of recent seismicity across the broad geographic region of the Haynesville shale play, which encompasses parts of eastern Texas and northwestern Louisiana. We utilize temporary (~2 years) deployments of seismographs during the USArray Transportable Array experiment and analyze seismicity from February 2010 through the end of 2012. In addition to generating a seismicity catalog through standard detection methodologies, we utilize a matched-filter technique whose widespread use in seismology is able to detect potential missing earthquakes within continuous seismograms. We identify many earthquakes in eastern Texas and Louisiana that had not been previously identified. While some earthquakes exist outside two distinct zones, most seismicity is confined to zones near Timpson, in east Texas, and Bienville Parish, in northwestern Louisiana. The Timpson sequence has been studied and discussed extensively by Frohlich et al. (2014). In Bienville Parish, a total of 8 earthquakes between magnitudes 1-2.4 occurred over just a few months (August-October 2011). Further, during this activity a number of the smaller magnitude earthquakes occur without a preceding larger event, which is consistent with classification as a seismic swarm. We are currently investigating the environmental conditions (i.e. injection/production values) associated with the Bienville Parish sequence and will present our findings at the meeting. Regulatory records indicate the existence of 51 active injection wells in Bienville Parish, though the data is inconsistently reported and appears to be missing for all wells prior to 2012. We are currently investigating this issue. This work highlights the continued need for investments in monitoring seismicity in areas of active oil and gas extraction.